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Ethereal User's Guide

1. H ADOMWDDHO WHOOO 12 IN NO EVE F UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING ILL ANY COPYRI HOLDER OR ANY OTHI PARTY WHO MAY MODIFY AND OR EDISTRIBUTE TH ROGRAM AS PERMITTED ABOVE BE LIABLE TO YOU FOR DAMAGES NCLUDING ANY G RAL SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING HE P ED I m U AH R A N i m UT OF THE USE OR INABILITY TO USE T ROGRAM INCLUDING BUT NOT LIMITED O LOSS OF DATA OR DATA BEING RENDERE NACCURATE OR LOSSES SUSTAINED BY OU OR THIRD PARTIES OR A FAILURE OF HE PROGRAM TO OPERATE WITH ANY OTHER ROGRAMS EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES E2 UKHOHDS HHO END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs If you develop a new program and you want it to be of the greatest possible use to the public the best way to achieve this is to make it free software which everyone can redistribute and change under these terms To do so attach the following notices to the program It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty and each
2. Set Time Reference toggle Toggles the time reference state of the currently selected packet to on or off e Find Next Find the next time referenced packet in the Packet List pane e Find Previous Find the previous time referenced packet in the Packet List pane Figure 6 11 Ethereal showing a time referenced packet File Edit Yiew Go Capture Analyze Statistics Help BHAAe ocM xr eS Qerxrv Ft Bag DZ Eiter Po x dP Expression Ys dear yf apply No Time Source Destination Protocol Info 1 0 000000 192 168 0 2 Broadcast who has 192 168 0 2 Gratuitous gt 4 0 726445 192 168 0 2 igmp mcast net V3 Membership Report 10 REF E 0 2 g stand e ont ww004 lt Frame 10 87 bytes on wire 87 bytes captured Ethernet II Src 192 168 0 2 00 0b 5d 20 cd 02 Ost Netgear_2d 75 9a 00 09 5b 2d 75 9a Internet Protocol Src 192 168 0 2 192 168 0 2 DSt 192 168 0 1 192 168 0 1 User Datagram Protocol Src Port 3026 3026 Ost Port domain 53 H Domain Name System query 0050 65 74 00 00 01 00 01 siere File Tm cas testcap 14 KB 00 00 02 A time referenced packet will be marked with the string REF in the Time column see packet number 10 All subsequent packets will show the time since the last time reference 120 Working with captured packets 121 Chapter 7 Advanced Topics 7 1 Introduction In this chapter some of the advance
3. Day 1970 01 01 Note 01 02 03 12345 6 The fields Time of Day Date and Time of Day Seconds Since Beginning of Capture and Seconds Since Previous Packet are mutually exclusive Time Display Format gt Time Selecting this tells Ethereal to display time stamps in time of day format of Day see Section 6 9 Time display formats and time references 01 02 03 12345 6 Time Display Format gt Selecting this tells Ethereal to display time stamps in seconds since be Seconds Since ginning of capture format see Section 6 9 Time display formats and Beginning of time references Capture 123 123456 Time Display Format gt Selecting this tells Ethereal to display time stamps in seconds since previ Seconds Since ous packet format see Section 6 9 Time display formats and time refer Previous Pack et 1 123456 ences Time Display Format gt Time Display Format gt Auto matic File Format Preci sion Selecting this tells Ethereal to display time stamps with the precision giv en by the capture file format used see Section 6 9 Time display formats and time references Note The fields Automatic Seconds and seconds are mu tually exclusive Time Display Format gt Selecting this tells Ethereal to display time stamps with a precision of Seconds 0 one second see Section 6 9 Time display formats and time references Time Display Fo
4. Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O0 0b Sd 20 cd 02 Ost Broadcast ff ff ff ff ff ft Address Resolution Protocol request gratuitous ARP ff Tf Tf ff ff ff 00 Ob Sd 20 cd 02 08 06 OO 01 08 00 06 04 00 01 00 Ob Sd 20 cd 02 cO as 00 02 00 00 00 00 00 00 cO ag 00 02 D test cap 14 KB 00 00 02 P 120 D 120 M 0 Table 3 2 Edit menu items Menu Item Accelerator Description Find Packet Ctrl F This menu item brings up a dialog box that allows you to find a packet by many criteria There is further information on finding packets in Sec tion 6 6 Finding packets Find Next Ctrl N This menu item tries to find the next packet matching the settings from Find Packet Find Previous Ctrl B This menu item tries to find the previous packet matching the settings from Find Packet Time Reference Ctr1 T gt Set Time Ref This menu item set a time reference on the currently selected packet See erence toggle Section 6 9 1 Packet time referencing for more information about the time referenced packets Time Reference gt Find Next This menu item tries to find the next time referenced packet 37 User Interface Menu Item Accelerator Description Time Reference gt Find Previ This menu item tries to find the previous time referenced packet ous Mark Packet Ctrl M toggle This menu item m
5. Higher level checksums are traditionally calculated by the protocol implementation and the com pleted packet is then handed over to the hardware Recent network hardware can perform advanced features such as IP checksum calculation also known as checksum offloading The network driver won t calculate the checksum itself but simply hand over an empty zero or garbage filled checksum field to the hardware Note Checksum offloading often causes confusion as the network packets to be transmitted are handed over to Ethereal before the checksums are actually calculated Ethereal gets these empty checksums and displays them as invalid even though the packets will contain valid checksums when they leave the network hardware later Checksum offloading can be confusing and having a lot of invalid messages on the screen can be quite annoying As mentioned above invalid checksums may lead to unreassembled packets mak ing the analysis of the packet data much harder You can do two things to avoid this checksum offloading problem e Turn off the checksum offloading in the network driver if this option is available e Turn off checksum validation of the specific protocol in the Ethereal preferences 135 Advanced Topics 136 Chapter 8 Statistics 8 1 Introduction Ethereal provides a wide range of network statistics These statistics range from general information about the loaded capture file like the number of c
6. Fibre Channel H 225 RAS LDAP mace ONC RPC RTP SCTP SIP VolP Calls T WAP WSP BOOTP DHCP HTTP ISUP Messages ONC RPC Programs tre Frame 1 42 bytes on wire 42 Ethernet II Src 192 168 0 2 Address Resolution Prot Uaa Broadcast ff ff ff ff ff ft poo fF tt ff tt ff ff 00 ob sd 08 00 06 04 00 01 00 Ob 00 00 00 00 00 00 cO ag address Resolution Protocol arp 28 bytes P 120 D 120M 0 All menu items will bring up a new window showing specific statistical information Table 3 7 Statistics menu items Menu Item Accelerator Description Summary Show information about the data captured see Section 8 2 The Sum mary window Protocol Hier archy Display a hierarchical tree of protocol statistics see Section 8 3 The Protocol Hierarchy window Conversations Display a list of conversations traffic between two endpoints see Sec tion 8 5 2 The Conversations window Endpoints Display a list of endpoints traffic to from an address see Section 8 4 2 The Endpoints window IO Graphs Display user specified graphs e g the number of packets in the course of time see Section 8 6 The IO Graphs window 49 User Interface Menu Item Accelerator Description Conversation List Display a list of conversations obsoleted by the combined window of Conversations abo
7. Print Ctrl P Quit Ctr Q as XML PSML packet summary File as XML PDML packet details file Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O0 0b Sd 20 cd 02 Ost Broadcast ff ff ff ff ff tt Address Resolution Protocol request gratuitous ARP oooo ff ff ff ff ff TF 00 Ob Sd 20 cd 02 08 O6 OO 01 0010 08 OO 06 04 00 01 00 Ob Sd 20 cd 02 cO ag 00 02 0020 00 00 00 00 00 00 cO ag 00 02 File Ts test cap 14 KB 00 00 02 P 120 D 120 M 0 Table 3 1 File menu items Menu Item Accelerator Description Open Ctrl O This menu item brings up the file open dialog box that allows you to load a capture file for viewing It is discussed in more detail in Section 5 2 1 The Open Capture File dialog box Open Recent This menu item shows a submenu containing the recently opened capture files Clicking on one of the submenu items will open the corresponding capture file directly Merge This menu item brings up the merge file dialog box that allows you to merge a capture file into the currently loaded one It is discussed in more detail in Section 5 4 Merging capture files Close Ctrl W This menu item closes the current capture If you haven t saved the cap ture you will be asked to do so first this can be disabled by a preference setting 34 User Interface Menu Item Accelerator Description Save Ctrl
8. List Files dialog box 87 File Input Output and Printing Ethereal 12 Files in Set Filename Created Last Modified Size test_00001_20060420183910 pcap 2006 04 20 18 39 10 2006 04 20 18 39 14 1113 Bytes test_00001_20060420185445 pcap 2006 04 20 18 54 4 test_00001_20060420190511 pcap test_00001_20060420191351 pcap test_00001_20060420191527 pcap test_00001_20060420232406 pcap test_00107_20060420184058 pcap test_00108_20060420184058 pcap test_00109_20060420184058 pcap test_00110_20060420184058 pcap test_00111_20060420184058 pcap test_00111_20060420185557 pcap o in directory D test Each line contains information about a file of the file set e Filename the name of the file If you click on the filename or the radio button left to it the current file will be closed and the corresponding capture file will be opened e Created the creation time of the file e Last Modified the last time the file was modified e Size the size of the file The last line will contain info about the currently used directory where all of the files in the file set can be found The content of this dialog box is updated each time a capture file is opened closed The Close button will well close the dialog box 88 File Input Output and Printing 5 6 Exporting data Ethereal provides several ways and formats to export packet data This section describes general ways to export da
9. userll USER 11 userl2 USER 12 userl3 USER 13 userl4 USER 14 userl5 USER 15 symantec Symantec Enterprise Firewall ap1394 Apple IP over IEEE 1394 bacnet ms tp BACnet MS TP default is the same as the first input file F lt capture type gt capture file type to write libpcap libpcap tcpdump Ethereal etc rh6_llibpcap RedHat Linux 6 1 libpcap tcpdump suse6_3libpcap SuSE Linux 6 3 libpcap tcpdump modlibpcap modified libpcap tcpdump nokialibpcap Nokia libpcap tcpdump lanalyzer Novell LANalyzer ngsniffer Network Associates Sniffer DOS based snoop Sun snoop netmonl Microsoft Network Monitor 1 x netmon2 Microsoft Network Monitor 2 x 185 Related command line tools ngwsniffer_1l_1 Network Associates Sniffer Windows based 1 1 ngwsniffer_2_0 Network Associates Sniffer Windows based 2 00x visual Visual Networks traffic capture 5views Accellent 5Views capture niobserverv9 Network Instruments Observer version 9 default is libpcap h Prints the version and options and exits v Causes mergecap to print a number of messages while it s working a Causes the frame timestamps to be ignored writing all packets from the first input file fol lowed by all packets from the second input file By default when a is not specified the con tents of the input files are merged in chronological order based on each frame s timestamp Note
10. 101 Working with captured packets Mark Packet toggle This menu item is the same as the Edit menu item of the same name It allows you to mark a packet Time Reference This menu item is the same as the Edit menu items of the same name It allows you to set and work with time refer ences Apply as Filter This menu item is the same as the Analyze menu items of the same name Prepare a Filter This menu item is the same as the Analyze menu items of the same name Follow TCP Stream This menu item is the same as the Analyze menu item of the same name It allows you to view all the data on a TCP stream between a pair of nodes Decode As This menu item is the same as the Analyze menu item of the same name Print This menu item is the same as the File menu item of the same name It allows you to print packets Show Packet in New Window This menu item is the same as the View menu item of the same name It allows you to display the selected packet in an other window Figure 6 4 Pop up menu of Packet Details pane test cap Ethereal DAR File Edit Yiew Go Capture Analyze Statistics Help BaHaA e oMx eSGaQeraFzt eggaa Weiter v Expression Ys clear Vf Apply No Time Source Destination Protocol Info 23 0 001026 2 168 0 9 68 0 2 1025 gt S000 ACK Seg 1 Ack 1 Wi Frame 23 60 bytes on wire 60 bytes captured Ethernet II Src Netgear_2d 75 9a O0 09 Sbi2d 75 9a Ost 192 168 0
11. 20 Building and Installing Ethereal 2 5 Installing the binaries under UNIX 2 5 1 2 5 2 In general installing the binary under your version of UNIX will be specific to the installation meth ods used with your version of UNIX For example under AIX you would use smit to install the Ethereal binary package while under Tru64 UNIX formerly Digital UNIX you would use setld Installing from rpm s under RedHat and alike Use the following command to install the Ethereal RPM that you have downloaded from the Ethere al web site rpm ivh ethereal 0 10 5 0 2 2 1386 rpm If the above step fails because of missing dependencies install the dependencies first and then retry the step above See Example 2 4 Installing required RPMs under RedHat Linux 6 2 and beyond for information on what RPMs you will need to have installed Installing from deb s under Debian Use the following command to install Ethereal under Debian apt get install ethereal apt get should take care of all of the dependency issues for you 21 Building and Installing Ethereal 2 6 Troubleshooting during the install on Unix A number of errors can occur during the installation process Some hints on solving these are provided here If the configure stage fails you will need to find out why You can check the file config log in the source directory to find out what failed The last few lines of this file should help in determining th
12. Go Forward command cceeeeeceeceeceecneeeeeeeeececeeeeceseneresenereeenenes 117 6 7 3 The Go to Packet dialog Dox 2 55 scsi asscisd ess sscssaes sedseesess pad o ETEek PES EESE 117 6 7 4 The Go to Corresponding Packet command cc cee cece eee ceeeee teen eeee seen eeaes 117 6 7 5 The Go to First Packet command siessen annaa e A E ETa 117 6 7 6 The Go to Last Packet command cceeeeeeeeceeeeeceeeeeeereeeereeeereseereseneres 117 6 8 Marking packets sos ss sierraad oE EE EErEE E PEES ER rP OESE REEE EEEE EE votes speeds 118 6 9 Time display formats and time references esessesrsseerrseesrrrrrrreresrrersrreererrerreresrse 119 6 9 1 Packet time referencing nsss oin e RE E A N SEEST 119 T AGVanCed TOPICS kedan erea e ea E E EEEE e A E EEE iE S TEE 122 Tl Introd cton oreen n aeee e E EEE RE ENEE EER E T EAA RE EEEE E Ea 122 1 2 Folowme TCP streams Aip e e a a e e a a a S A aas 123 7 2 1 The Follow TCP Stream dialog bOX 20 0 0 cece sec ee ce ee eens ce eeeeeeeeeeaeeeaeeenes 123 Ta TIME Stamps eean es e E a E we desngwee Boesh A eta shee rtes a Mesh E 125 UA Etherealantermals sirnani a E E EE EA T 125 7 32 Capture file formats sprin ei e ne E E a E a E EE 125 T33 ACCURACY vetat epre eE a Eno paee arae Ea S gusta aare 125 TA MMe Zones v5 hee naa nne R nE AE OARA TEE AIA ATE POATEN EEEE EP aE 127 7 4 1 Set your computer s time correct sssessssesrssseserererrrrr
13. The View menu for details While reading or writing capture files Ethereal converts the time stamp data between the capture file format and the internal format as required While capturing Ethereal uses the libpcap WinPcap capture library which supports microsecond resolution Unless you are working with specialized capturing hardware this resolution should be adequate Capture file formats Every capture file format that Ethereal knows support time stamps The time stamp precision sup ported by a specific capture file format differs widely and varies from one second 0 to one nano second 0 123456789 Most file formats store the time stamps with a fixed precision e g micro seconds while some file formats are even capable to store the time stamp precision itself whatever the benefit may be The common libpcap capture file format that is used by Ethereal and a lot of other tools supports a fixed microsecond resolution 0 123456 only Note Writing data into a capture file format that doesn t provide the capability to store the actual precision will lead to loss of information Example If you load a capture file with nanosecond resolution and store the capture data to a libpcap file with micro second resolution Ethereal obviously must reduce the precision from nanosecond to microsecond Accuracy It s often asked Which time stamp accuracy is provided by Ethereal Well Ethereal doesn t cre ate any time s
14. This is displayed if you have selected a protocol field from the Packet Details pane Tip The value between the brackets in this example arp opcode can be used as a display filter string representing the selected protocol field 60 User Interface 61 Chapter 4 Capturing Live Network Data 4 1 Introduction Capturing live network data is one of the major features of Ethereal The Ethereal capture engine provides the following features e Capture from different kinds of network hardware Ethernet Token Ring ATM e Stop the capture on different triggers like amount of captured data captured time captured number of packets e Simultaneously show decoded packets while keep on capturing e Filter packets reducing the amount of data to be captured see Section 4 8 Filtering while cap turing e Capturing into multiple files while doing a long term capture and in addition the option to form a ringbuffer of these files keeping only the last x files useful for a very long term capture see Section 4 6 Capture files and file modes The capture engine still lacks the following features e Simultaneous capturing from multiple network interfaces however you can start multiple in stances of Ethereal and merge capture files later e Stop capturing or doing some other action depending on the captured data 62 Capturing Live Network Data 4 2 Prerequisites Se
15. and or evaluate from Ethereal specific configuration files For details about the configuration files Ethereal uses for name resolution and alike see Appendix A Configuration and other Files and Folders The name resolution feature can be en disabled separately for the protocol layers of the following sections Name Resolution drawbacks Name resolution can be invaluable while working with Ethereal and may save you even hours of work Unfortunately it also has it s drawbacks e Name resolution will often fail The name to be resolved might simply be unknown by the name servers asked or the servers are just not available and the name is also not found in Ethere al s configuration files e The resolved names are not stored in the capture file or somewhere else So the resolved names might not be available if you open the capture file later or on a different machine Each time you open a capture file it may look slightly different maybe simply because you can t connect a name server which you could connect before e DNS may add additional packets to your capture file You may see packets to from your ma chine in your capture file which are caused by name resolution network services of the machine Ethereal captures from XXX are there any other such packets than DNS ones e Resolved DNS names are cached by Ethereal This is required for acceptable performance However if the name resolution information should change while Ether
16. e How to colorize the packet list e How to control protocol dissection e How to use the various preference settings 151 Customizing Ethereal 9 2 Start Ethereal from the command line You can start Ethereal from the command line but it can also be started from most Window man agers as well In this section we will look at starting it from the command line Ethereal supports a large number of command line parameters To see what they are simply enter the command ethereal h and the help information shown in Example 9 1 Help information avail able from Ethereal or something similar should be printed Example 9 1 Help information available from Ethereal This is ethereal 0 10 13 C 1998 2005 Gerald Combs lt gerald ethereal com gt Compiled with GTK 2 6 9 with GLib 2 6 6 with WinPcap version unknown with libz 1 2 3 with libpcre 6 3 with Net SNMP 5 2 1 2 with ADNS Running with WinPcap version 3 1 packet dll version 3 1 0 27 based on lib cap version 0 9 x on Windows XP Service Pack 2 build 2600 ethereal vh DklLnpQS a lt capture autostop condition gt b lt capture ring buffer option gt B lt capture buffer size gt c lt capture packet count gt f lt capture filter gt g lt packet number gt i lt capture interface gt m lt font gt N lt name resolving flags gt o lt preference recent setting gt r lt infile gt R
17. port numbers the argument is a string that may contain the letters m to enable MAC address resolution n to enable net work address resolution and t to enable transport layer port number resolution This overrides n if both N and n are present The letter C enables concurrent asynchronous DNS lookups 0 lt preference recent settings gt Sets a preference or recent value overriding the default value and any value read from a preference recent file The argu ment to the flag is a string of the form prefname value where prefname is the name of the preference which is the same name that would appear in the preference recent file and value is the value to which it should be set Multiple instances of o lt preference settings gt can be given on a single com mand line An example of setting a single preference would be ethereal o mgcp display_dissect_tree TRUE An example of setting multiple preferences would be ethereal 0 mgcp display_dissect_tree TRUE 0 mgcp udp callagent_port 2627 154 Customizing Ethereal Tip S You can get a list of all available preference strings from the preferences file see Ap pendix A Configuration and other Files and Folders p Don t put the interface into promiscuous mode Note that the interface might be in promiscuous mode for some other reas on hence p cannot be used to ensure that the only traffic that is captured is traffic sent to or from the machine on which
18. 02 03 gt Netgear_01 02 03 132 Advanced Topics 7 6 3 IP name resolution network layer 7 6 4 7 6 5 Try to resolve an IP address e g 65 208 228 223 to something more human readable DNS ADNS name resolution system library service Ethereal will ask the operating system or the ADNS library to convert an IP address to the hostname associated with it e g 65 208 228 223 gt www ethereal com The DNS service is using synchronous calls to the DNS server So Ethereal will stop responding until a response to a DNS request is returned If possible you might consider using the ADNS library which won t wait for a network response A Warning Enabling network name resolution when your name server is unavailable may signific antly slow down Ethereal while it waits for all of the name server requests to time out Use ADNS in that case DNS vs ADNS here s a short comparison Both mechanisms are used to convert an IP address to some human readable domain name The usual DNS call gethostname will try to convert the ad dress to a name To do this it will first ask the systems hosts file e g etc hosts if it finds a match ing entry If that fails it will ask the configured DNS server s about the name So the real difference between DNS and ADNS comes when the system has to wait for the DNS server about a name resolution The system call gethostname will wait until a name is resolved or an error occurs If t
19. 1 7 1 Website You will find lot s of useful information on the Ethereal homepage at http www ethereal com 1 7 2 Wiki The Ethereal Wiki at http wiki ethereal com provides a wide range of information related to Ether eal and packet capturing in general You will find a lot of information not part of this user s guide For example there is an explanation how to capture on a switched network an ongoing effort to build a protocol reference and a lot more And best of all if you would like to contribute your knowledge on a specific topic maybe a net work protocol you know well you can edit the wiki pages by simply using your webbrowser 1 7 3 FAQ The Frequently Asked Questions will list often asked questions and the corresponding answers Read the FAQ Before sending any mail to the mailing lists below be sure to read the FAQ as it will often answer the question s you might have This will save yourself and others a lot of time keep in mind that a lot of people are subscribed to the mailing lists You will find the FAQ inside Ethereal by clicking the menu item Help Contents and selecting the FAQ page in the upcoming dialog An online version is available at the ethereal website http www ethereal com fag html You might prefer this online version as it s typically more up to date and the HTML format is easier to use 1 7 4 Mailing Lists There are several mailing lists of specific Ethereal topics available e
20. 16 bit 24 bit 32 bit Boolean Ethernet address 6 bytes eth addr ff ff ff ff ff ff A boolean field is present in the protocol decode only if its value is true For example tcp flags syn is present and thus true only if the SYN flag is present in a TCP segment header Thus the filter expression tep flags syn will select only those packets for which this flag exists that is TCP segments where the segment header contains the SYN flag Similarly to find source routed token ring pack ets use a filter expression of tr sr IPv4 address ip addr 192 168 0 1 IPv6 address IPX network number String text Double precision floating point number 6 3 3 Combining expressions You can combine filter expressions in Ethereal using the logical operators shown in Table 6 4 Display Filter Logical Operations Visplay Filter Logical perations 108 Working with captured packets Table 6 4 Display Filter Logical Operations English C like Description and example and amp amp Logical AND ip addr 10 0 0 5 and tcp flags fin or Il Logical OR ip addr 10 0 0 5 or ip addr 192 1 1 1 xor An Logical XOR tr dst 0 3 0 6 29 xor tr src 0 3 0 6 29 not Logical NOT not Irc Substring Operator Ethereal allows you to select subsequences of a sequence in rather elaborate ways After a label you can place a pair of brac
21. 1t2 lt 5 coin 3 fcostass sy bas ad Gee ota sts Cones fee E E eee 190 Di8 2 Why do TMS c aorte seine atoi enia Eo aie es ec tee bassist E hiss 190 D 8 3 How to used 2Zeth 3 soss sss teia ena e conaasaspavsades sateen seoeababaaeeaaana AEEA 190 D843 TODO ccspveusben tuescosdyten Mune sods con pneth vendor ee E E e AE EA NAER T EER eE 191 D 8 5 Limitations eiir ae EEE PE E E EEA E EE eE E EEO AR 192 D8 O NOES on na a a a e a a aaae a a e a ea a RN 192 E This Document s License GPL necnon e n EE E E E E EE EE E GEES 194 vii Preface 1 Foreword Ethereal is one of those programs that many network managers would love to be able to use but they are often prevented from getting what they would like from Ethereal because of the lack of documentation This document is part of an effort by the Ethereal team to improve the usability of Ethereal We hope that you find it useful and look forward to your comments Vili Preface 2 Who should read this document The intended audience of this book is anyone using Ethereal This book will explain all the basics and also some of the advanced features that Ethereal provides As Ethereal has become a very complex program since the early days not every feature of Ethereal might be explained in this book This book is not intended to explain network sniffing in general and it will not provide details about specific network protocols A lot of useful information regarding
22. 2 O00 0b 5d 20 cd 02 Internet Protocol Src 192 168 0 1 192 168 0 1 Ost 192 168 0 2 192 168 0 2 Transmission Control Prot aan ms OSt Port seq 1 Ac Expand Subtrees Expand All Collapse All Apply as Filter Selected Prepare a Filter gt Not Selected Follow TCP Stream and Selected or Selected and not Selected or not Selected Wiki Protocol Page Filter Field Reference Protocol Preferences 3 Decode As Transmission Control Protocol tcp 20 bytes P 120 D 120M 0 102 Working with captured packets Expand Subtrees Expand All Collapse All Apply as Filter Prepare a Filter Follow TCP Stream Wiki Protocol Page Filter Field Reference Protocol Properties Decode As Resolve Name Go to Corresponding Packet This menu item expands the currently selected subtree This menu item expands all subtrees in all packets in the cap ture Ethereal keeps a list of all the protocol subtrees that are ex panded and uses it to ensure that the correct subtrees are ex panded when you display a packet This menu item collapses the tree view of all packets in the capture list This menu item is the same as the Analyze menu items of the same name This menu item is the same as the Analyze menu items of the same name This menu item is the same as the Analyze menu item of the same name It allows you to view all the data on a TCP stream between a pair of
23. ARP whereas generating a dummy Ethernet header with e works for any sort of L3 packet Include dummy UDP headers before each packet Specify the source and destination UDP ports for the packet in decimal Use this option if your dump is the UDP payload of a packet but does not include any UDP IP or Ethernet headers Note that this automatically in cludes appropriate Ethernet and IP headers with each packet Ex ample u 1000 69 to make the packets look like TFTP UDP packets 189 Related command line tools D 8 idil2eth Creating dissectors from Corba IDL files D 8 1 D 8 2 D 8 3 In an ideal world idl2eth would be mentioned in the users guide in passing and documented in the developers guide As the developers guide has not yet been completed it will be documented here What is it As you have probably guessed from the name idl2eth takes a user specified IDL file and attempts to build a dissector that can decode the IDL traffic over GIOP The resulting file is C code that should compile okay as an ethereal dissector id 2eth basically parses the data struct given to it by the omniidl compiler and using the GIOP API available in packet giop ch generates get_CDR_xxx calls to decode the CORBA traffic on the wire It consists of 4 main files README id1l2eth This document ethereal_be py The main compiler backend ethereal_gen py A helper class that generates the C code idl2eth
24. Ethereal is running broadcast traffic and multicast traffic to addresses received by that machine Q This option forces Ethereal to exit when capturing is com plete It can be used with the c option It must be used in conjunction with the i and w options r lt infile gt This option provides the name of a capture file for Ethereal to read and display This capture file can be in one of the formats Ethereal understands R lt read display filter gt This option specifies a display filter to be applied when read ing packets from a capture file The syntax of this filter is that of the display filters discussed in Section 6 2 Filtering pack ets while viewing Packets not matching the filter are dis carded s lt capture snaplen gt This option specifies the snapshot length to use when captur ing packets Ethereal will only capture lt snaplen gt bytes of data for each packet S This option specifies that Ethereal will display packets as it captures them This is done by capturing in one process and displaying them in a separate process This is the same as Up date list of packets in real time in the Capture Options dialog box t lt time stamp format gt This option sets the format of packet timestamps that are dis played in the packet list window The format can be one of e rrelative which specifies timestamps are displayed relat ive to the first packet captured e a absolute which specifies that actu
25. S This menu item saves the current capture If you have not set a default capture file name perhaps with the w lt capfile gt option Ethereal pops up the Save Capture File As dialog box which is discussed further in Section 5 3 1 The Save Capture File As dialog box Note If you have already saved the current capture this menu item will be greyed out Note You cannot save a live capture while it is in progress You must stop the capture in order to save Save As Shift Ctrl S This menu item allows you to save the current capture file to whatever file you would like It pops up the Save Capture File As dialog box which is discussed further in Section 5 3 1 The Save Capture File As dialog box File Set gt List Files File Set gt Next File This menu item allows you to show a list of files in a file set It pops up the Ethereal List File Set dialog box which is discussed further in Sec tion 5 5 File Sets If the currently loaded file is part of a file set jump to the next file in the set If it isn t part of a file set or just the last file in that set this item is greyed out File Set gt Pre vious File If the currently loaded file is part of a file set jump to the previous file in the set If it isn t part of a file set or just the first file in that set this item is greyed out Export gt as Plain Text file Export gt as PostScript file This me
26. Seq 1 Ack 1 Wil lt il Frame 36 60 bytes on wire 60 bytes captured Ethernet II Src Netgear_2d 75 9a O0 09 Sb 2d 75 9a Ost 192 168 0 2 O00 0b S5d 20 cd 02 Internet Protocol Src 192 168 0 1 192 168 0 1 Dst 192 168 0 2 192 168 0 2 B Transmission Control Protocol Src Port http 80 Dst Port 3197 3197 Seq 20 Ack 190 Len O Source port http 80 Destination port 3197 3197 sequence number 20 relative sequence number Acknowledgement number 190 relative ack number Header length 20 bytes Flags Ox0011 FIN ACK Window size 3072 Checksum Ox93ca correct SEQ ACK analysis Ob 5d 20 cd 02 00 09 2d 75 9a 08 00 45 00 28 00 84 00 00 40 06 f cO a8 00 01 cO as 02 00 50 Oc 7d 00 00 14 50 11 00 93 ca 00 00 00 00 oo 00 00 acknowledgement number tcp ack 4 bytes P 120 D 120 M 0 You can also select and view packets the same way while Ethereal is capturing if you selected Up date list of packets in real time in the Ethereal Capture Preferences dialog box In addition you can view individual packets in a separate window as shown in Figure 6 2 Viewing a packet in a separate window Do this by selecting the packet you are interested in the packet list pane and then select Show Packet in New Windows from the Display menu This allows you to easily compare two or even more packets 99 Working with captured packets Figure 6 2 Viewing a packet in a separate window 36
27. Tx Bytes Rx Packets Rx Bytes Netgear_2d 75 9a 114 62 7313 52 5515 192 168 0 2 120 58 6060 62 7313 01 00 5e 00 00 16 2 Apply as Filter i Selected 01 00 5e 7f ff fa 1 Prepare a Filter gt Not Selected Find Frame gt and Selected Colorize Host Traffic vor Selected and not Selected or not Selected Name resolution For each supported protocol a tab is shown in this window The tab labels shows the number of en dpoints captured e g the tab label Ethernet 5 tells you that five ethernet endpoints have been captured If no endpoints of a specific protocol were captured the tab label will be grayed out although the related page can still be selected Each row in the list shows the statistical values for exactly one endpoint Name resolution will be done if selected in the window and if it is active for the specific protocol layer MAC layer for the selected Ethernet endpoints page As you might have noticed the first row has a name resolution of the first three bytes Netgear the second row s address was resolved to an IP address using ARP and the third was resolved to a broadcast unresolved this would still be ff ff ff ff ff ff the last two Ethernet addresses remain unresolved Tip This window will be updated frequently so it will be useful even if you open it before or while you are doing a live capture The protocol specific Endpoint List windows Before the combined window described above was availabl
28. a long time 56 User Interface 3 15 The Packet List pane The packet list pane displays all the packets in the current capture file Figure 3 13 The Packet List pane No Time Source Destination Protocol Info e 00 1 6 Broadcast ARP who has 13 1 32 168 0 IBNS ame is 4 0 726445 192 168 0 2 IGMP V3 Membership Report v a il i Each line in the packet list corresponds to one packet in the capture file If you select a line in this pane more details will be displayed in the Packet Details and Packet Bytes panes While dissecting a packet Ethereal will place information from the protocol dissectors into the columns As higher level protocols might overwrite information from lower levels you will typic ally see the information from the highest possible level only For example let s look at a packet containing TCP inside IP inside an Ethernet packet The Ethernet dissector will write its data such as the Ethernet addresses the IP dissector will overwrite this by its own such as the IP addresses the TCP dissector will overwrite the IP information and so on There are a lot of different columns available Which columns are displayed can be selected by pref erence settings see Section 9 5 Preferences The default columns will show e No The number of the packet in the capture file This number won t change even if a display filter is used e Time The timestamp of the packet The presen
29. address 1 2 3 4 Then they use ip addr 1 2 3 4 to see all packets not containing the IP address 1 2 3 4 in it Unfor tunately this does not do the expected Instead that expression will even be true for packets where either source or destination IP address equals 1 2 3 4 The reason for this is that the expression ip addr 1 2 3 4 must be read as the packet contains a field named ip addr with a value different from 1 2 3 4 As an IP datagram con tains both a source and a destination address the expression will evaluate to true whenever at least one of the two addresses differs from 1 2 3 4 If you want to filter out all packets containing IP datagrams to or from IP address 1 2 3 4 then the correct filter is ip addr 1 2 3 4 as it reads show me all the packets for which it is not true that a field named ip addr exists with a value of 1 2 3 4 or in other words filter out all packets for which there are no occurrences of a field named ip addr with the value 1 2 3 4 110 Working with captured packets 6 4 The Filter Expression dialog box When you are accustomed to Ethereal s filtering system and know what labels you wish to use in your filters it can be very quick to simply type a filter string However if you are new to Ethereal or are working with a slightly unfamiliar protocol it can be very confusing to try to figure out what to type The Filter Expression dialog box helps with this Tip The Filter
30. atm pdus ATM PDUs atm pdus untruncated ATM PDUs untruncated null NULL ascend Lucent Ascend access equipment isdn ISDN ip over fc RFC 2625 IP over Fibre Channel pep with direction PPP with Directional Info ieee 802 11 IEEE 802 11 Wireless LAN prism IEEE 802 11 plus Prism II monitor mode header ieee 802 11 radio IEEE 802 11 Wireless LAN with radio informatio E 802 11 plus BSD WLAN header FIND r A 802 11 bsd IEE i 802 11l avs IEEE 802 11 plus AVS WLAN header linux sll Linux cooked mode capture frelay Frame Relay frelay with direction Frame Relay with Directional Info chdlc Cisco HDLC ios Cisco IOS internal ltalk Localtalk pflog old OpenBSD PF Firewall logs pre 3 4 hhdlc HiPath HDLC docsis Data Over Cable Service Interface Specification c wW S osine CoSine L2 debug log hdlc Wellfleet HDLC dlc SDLC zsp Tazmen sniffer protocol nc OpenBSD enc 4 encapsulating interface pflog OpenBSD PF Firewall logs chdlc with direction Cisco HDLC with Directional Info bluetooth h4 Bluetooth H4 mtp2 SS7 MTP2 mtp3 SS7 MTP3 irda IrDA user0 USER 0 userl USER 1 user2 USER 2 user3 USER 3 user4 USER 4 user5 USER 5 user6 USER 6 user7 USER 7 user8 USER 8 user9 USER 9 userl0 USER 10
31. based Sniffer and Net work Instruments Observer formats save the arrival time of packets as local time values Internally to Ethereal time stamps are represented in UTC this means that when reading capture files that save the arrival time of packets as local time values Ethereal must convert those local time values to UTC values Ethereal in turn will display the time stamps always in local time The displaying computer will con vert them from UTC to local time and displays this local time For capture files saving the arrival time of packets as UTC values this means that the arrival time will be displayed as the local time in your time zone which might not be the same as the arrival time in the time zone in which the packet was captured For capture files saving the arrival time of packets as local time values the conversion to UTC will be done using your time zone s offset from UTC and DST rules which means the con version will not be done correctly the conversion back to local time for display might undo this cor rectly in which case the arrival time will be displayed as the arrival time in which the packet was captured 128 Advanced Topics Table 7 1 Time zone examples for UTC arrival times without DST Los Angeles New York Madrid London Berlin Tokyo Capture File 10 00 10 00 10 00 10 00 10 00 10 00 UTC Local Offset 8 5 1 0 1 9 to UTC Displayed 02 00 05 00 09 00 10 00 11 00 19 00 Time Local Tim
32. cap ture files Their name is based on the number of the file and on the creation date and time 152 Customizing Ethereal B lt capture buffer size Win32 only gt c lt capture packet count gt D f lt capture filter gt g lt packet number gt h i lt capture interface gt When the first capture file fills up Ethereal will switch to writing to the next file until it fills up the last file at which point it ll discard the data in the first file unless 0 is spe cified in which case the number of files is unlimited and start writing to that file and so on If the optional duration is specified Ethereal will switch also to the next file when the specified number of seconds has elapsed even if the current file is not completely fills up iV Switch to the next file after value seconds have al elapsed even if the current file is not com durationue pletely filled up val Switch to the next file after it reaches a size of filesizeue value kilobytes where a kilobyte is 1000 bytes not 1024 bytes files value Begin again with the first file after value num ber of files were written form a ring buffer Win32 only set capture buffer size in MB default is 1MB This is used by the the capture driver to buffer packet data un til that data can be written to disk If you encounter packet drops while capturing try to increase this size This option specifies the maximum number of packets to
33. cap ture when capturing live data It would be used in conjunction with the k option Print a list of the interfaces on which Ethereal can capture and exit For each network interface a number and an inter face name possibly followed by a text description of the in terface is printed The interface name or the number can be supplied to the i flag to specify an interface on which to cap ture This can be useful on systems that don t have a command to list them e g Windows systems or UNIX systems lacking ifconfig a the number can be useful on Windows 2000 and later systems where the interface name is a somewhat com plex string Note that can capture means that Ethereal was able to open that device to do a live capture if on your system a program doing a network capture must be run from an account with special privileges for example as root then if Ethereal is run with the D flag and is not run from such an account it will not list any interfaces This option sets the initial capture filter expression to be used when capturing packets After reading in a capture file using the r flag go to the giv en packet number The h option requests Ethereal to print its version and usage instructions as shown above and exit Set the name of the network interface or pipe to use for live packet capture 153 Customizing Ethereal Network interface names should match one of the names lis ted in ethere
34. capture file Time the timestamps when the first and the last packet were capturing and the time between them Capture information from the time when the capture was done only available if the packet data was captured from the network and not loaded from a file Display some display related information Traffic some statistics of the network traffic seen If a display filter is set you will see values in both columns The values in the Captured column will remain the same as before while the values in the Displayed column will reflect the values corresponding to the packets shown in the display 139 Statistics 8 3 The Protocol Hierarchy window The protocol hierarchy of the captured packets Figure 8 2 The Protocol Hierarchy window Ethereal Protocol Hierarchy Statistics 100 00 13373 E Ethernet 100 00 Address Resolution Protocol 0 83 E Internet Protocol 99 17 User Datagram Protocol 10 83 NetBIOS Name Service 4 17 Domain Name Service 5 00 Hypertext Transfer Protocol 1 67 Internet Control Message Protocol 0 83 Internet Group Management Protocol 1 67 E Transmission Control Protocol 85 83 E Hypertext Transfer Protocol 11 67 E Line based text data 1 67 Hypertext Transfer Protocol 1 67 Malformed Packet 2 50 Data 5 00 This is a tree of all the protocols in the capture You can collapse or expand subtrees by clicking on the plus minus icons By default all trees are expanded E
35. com Introduction 1 3 Where to get Ethereal You can get the latest copy of the program from the Ethereal website ht tp www ethereal com download html The website allows you to choose from among several mir rors for downloading A new Ethereal version will typically become available every 4 8 weeks If you want to be notified about new Ethereal releases you should subscribe to the ethereal an nounce mailing list You will find more details in Section 1 7 4 Mailing Lists Introduction 1 4 A rose by any other name William Shakespeare wrote A rose by any other name would smell as sweet And so it is with Ethereal as there appears to be two different ways that people pronounce the name Some people pronounce it ether real while others pronounce it e the real as in ghostly insubstan tial etc You are welcome to call it what you like as long as you find it useful The FAQ gives the official pronunciation as e the real Introduction 1 5 A brief history of Ethereal In late 1997 Gerald Combs needed a tool for tracking down networking problems and wanted to learn more about networking so he started writing Ethereal as a way to solve both problems Ethereal was initially released after several pauses in development in July 1998 as version 0 2 0 Within days patches bug reports and words of encouragement started arriving so Ethereal was on its way to success Not long after t
36. file Export to file PostScript files can be easily converted to PDF files using ghostscript s ps2pdf Packet Range Packet Format Captured Displayed Packet summary line All packets 191 Packet details Selected packet only 1 Allcollapsed As displayed All expanded Specify a packet range _ Packet bytes C Each packet on a new page e Export to file frame chooses the file to export the packet data to e The Packet Range frame is described in Section 5 8 The Packet Range frame e The Packet Details frame is described in Section 5 9 The Packet Format frame 5 6 3 The Export as CSV Comma Seperated Values File dialog box XXX add screenshot Export packet summary into CSV used e g by spreadsheet programs to im export data e Export to file frame chooses the file to export the packet data to e The Packet Range frame is described in Section 5 8 The Packet Range frame 5 6 4 The Export as PSML File dialog box 90 File Input Output and Printing Export packet data into PSML This is an XML based format including only the packet summary Figure 5 7 The Export as PSML File dialog box Ethereal Export as PSML file fal All packets 191 191 Selected packet only ala ECS Only From first gt Specify a packet range tc O e Export to file frame chooses the file to export the pa
37. file should have at least the copyright line and a pointer to where the full notice is found lt one line to give the program s name and a brief idea of what it does gt Copyright C lt year gt lt name of author gt This program is free software you can redistribute it and or modify it under the terms of the GNU General Public License as published by the Free Software Foundation either version 2 of the License or at your option any later version This program is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU General Public License for more details You should have received a copy of the GNU General Public License along with this program if not write to the Free Software Foundation Inc 59 Temple Place Suite 330 Boston MA 02111 1307 USA Also add information on how to contact you by electronic and paper mail If the program is interactive make it output a short notice like this when it starts in an interactive mode Gnomovision version 69 Copyright C year name of author Gnomovision comes with ABSOLUTELY NO WARRANTY for details type show w This is free software and you are welcome to redistribute it under certain conditions type show c for details The hypothetical commands show w and show c should show the appropriate parts of the General Public Lice
38. filter and name resolution settings later while viewing the packets However for very large capture files it can take a significant amount of extra time changing these settings later so it might be a good idea to set at least the filter in advance here 5 2 2 Input File Formats 80 File Input Output and Printing The following file formats from other capture tools can be opened by Ethereal libpcap tcpdump and various other tools using tcpdump s capture format Sun snoop and atmsnoop Shomiti Finisar Surveyor captures Novell LANalyzer captures Microsoft Network Monitor captures AIX s iptrace captures Cinco Networks NetXray captures Network Associates Windows based Sniffer and Sniffer Pro captures Network General Network Associates DOS based Sniffer compressed or uncompressed cap tures AG Group WildPackets EtherPeek TokenPeek AiroPeek EtherHelp PacketGrabber captures RADCOM s WAN LAN Analyzer captures Network Instruments Observer version 9 captures Lucent Ascend router debug output HP UX s nett Toshiba s ISDN routers dump output ISDN4BSD i4btrace utility traces from the EyeSDN USB SO IPLog format from the Cisco Secure Intrusion Detection System pppd logs pppdump format the output from VMS s TCPIPtrace TCPtrace UCX TRACE utilities the text output from the DBS Etherwatch VMS utility Visual Networks Visual UpTime traffic capture the output from CoSine L2 debug the output from Accellent s 5Views LAN
39. idl gt packet test idl c You may wish to comment out the register_giop_user_module code and that will leave you with heuristic dissection If you don t want to use the shell script wrapper then try steps 3 or 4 instead 3 To write the C code to stdout Usage omniidl p b ethereal_be lt your file idl gt eg omniidl p b ethereal_b cho idl 4 To write to a file just redirect the output omniidl p b ethereal_b cho idl gt packet test idl c You may wish to comment out the register_giop_user_module code and that will leave you with heuristic dissection 5 Copy the resulting C code to your ethereal src directory edit the 2 make files to include the packet test idl c cp packet test idl c dir where ethereal lives edit Makefile am edit Makefile nmake 6 Run configure configure or autogen sh 7 Compile the code make 8 Good Luck D 8 4 TODO 191 Related command line tools 1 Exception code not generated yet but can be added manually 2 Enums not converted to symbolic values yet but can be added manually 3 Add command line options etc 4 More I am sure D 8 5 Limitations See the TODO list inside packet giop c D 8 6 Notes 1 The p option passed to omniidl indicates that the ethereal_be py and ethereal_gen py are residing in the current directory This may need tweaking if you place these files somewhere else 2 If it complains abo
40. istribute th h y ou must cause it w there is no warran and that users may tions and telling rmally print such a in part contains or is S S CY hese conditi he act of rom the Program Program Program s that you appropriate t all the f any warranty this License ng a copy and hange for a fee the Program or any portion py and f Section 1 ons carry prominent notices you distribute or p derived from the Pr a whole at no charg License fied program normally reads commands hen started running f nteractive use in the most ordinary way nnouncemen to print t including an appropriate copyright not or else saying t n the Progra his License ntire whole O9toan ct b My W a do not ap the date of any change ublish that in ogram or any e to all third interactively or such or display an ice anda hat you provide redistribute the program under the user how to view a copy of this Exception if the Program itself is interactive but n announcement your he Program is not required to print an announcement work based on nts apply to the modified work as a whole If ctions of that work are not derived from the Program nably considered independent and separate works in n this License and its terms ou distribute them as separate works B same sections as part of a whole which is a work based the distributi
41. local include net bpf h No such file or directory make install incl Error 1 If you do simply create the missing directory with the following command mkdir usr local include net and rerun the command make install incl Under RedHat 6 x and beyond and distributions based on it like Mandrake you can simply install each of the packages you need from RPMs Most Linux systems will install GTK and GLib in any case however you will probably need to install the devel versions of each of these packages The commands shown in Example 2 4 Installing required RPMs under RedHat Linux 6 2 and beyond will install all the needed RPMs if they are not already installed Example 2 4 Installing required RPMs under RedHat Linux 6 2 and beyond Building and Installing Ethereal cd mnt cdrom RedHat RPMS rpm rpm rpm rpm rpm ivh ivh ivh ivh ivh glib 1 2 6 3 1386 rpm glib devel 1 2 6 3 1386 rpm gtk 1 2 6 7 1386 rpm gtk devel 1 2 6 7 1386 rpm libpcap 0 4 19 1386 rpm Note If you are using a version of RedHat later than 6 2 the required RPMs have most likely changed Simply use the correct RPMs from your distribution Under Debian you can install Ethereal using apt get apt get will handle any dependency issues for you Example 2 5 Installing debs under Debian shows how to do this Example 2 5 Installing debs under Debian apt get install ethereal 18 Building a
42. lt read display filter gt s lt capture snaplen gt t lt time stamp format gt w lt savefile gt y lt capture link type gt X lt eXtension option gt z lt statistics gt lt infile gt We will examine each of the command line options in turn The first thing to notice is that issuing the command ethereal by itself will bring up Ethereal However you can include as many of the command line parameters as you like Their meanings are as follows in alphabetical order XXX is the alphabetical order a good choice Maybe better task based a lt capture autostop condition gt Specify a criterion that specifies when Ethereal is to stop writing to a capture file The criterion is of the form test value where test is one of iV Stop writing to a capture file after value of al seconds have elapsed durationue val Stop writing to a capture file after it reaches a filesizeue size of value kilobytes where a kilobyte is 1000 bytes not 1024 bytes If this option is used together with the b option Ethereal will stop writing to the current capture file and switch to the next one if filesize is reached files value Stop writing to capture files after value number of files were written b lt capture ring buffer option gt If a maximum capture file size was specified cause Ethereal to run in ring buffer mode with the specified number of files In ring buffer mode Ethereal will write to several
43. of all filter fields available through the menu item Help Supported Proto cols in the page Display Filter Fields of the upcoming dialog XXX add some more info here and a link to the statusbar info Comparing values You can build display filters that compare values using a number of different comparison operators They are shown in Table 6 2 Display Filter comparison operators Tip You can use English and C like terms in the same way they can even be mixed in a filter string Table 6 2 Display Filter comparison operators English C like Description and example eq Equal ip addr 10 0 0 5 ne l Not equal ip addr 10 0 0 5 gt gt Greater than frame pkt_len gt 10 It lt Less than 107 Working with captured packets English C like Description and example frame pkt_len lt 128 ge gt Greater than or equal to frame pkt_len ge 0x100 le lt Less than or equal to frame pkt_len lt 0x20 In addition all protocol fields are typed Table 6 3 Display Filter Field Types provides a list of the types and example of how to express them Table 6 3 Display Filter Field Types Type Example Unsigned integer 8 bit 16 bit 24 bit 32 bit You can express integers in decimal octal or hexa decimal The following display filters are equivalent ip len le 1500 ip len le 02734 ip len le 0x436 Signed integer 8 bit
44. original authors reputations Finally any free program is threatened constantly by software patents We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses in effect making the program proprietary To prevent this we have made it clear that any 194 This Document s License GPL patent must be licensed for everyo The precise terms and co modification follow Vs xr se or not TERMS AND CONDITIONS FO 0 This License applies a notice placed by the copyright holder sayi under the terms of this Ge GNU GENERAL PUBLIC LICI n nditions for copyi u n licensed at all g distribution and ENS T ry refers to any such program or work means either th that is to sa Yr La R COPYING DISTRIB to any program or UTION AND ther work MODIFICATION which contains ng it may be distributed neral Public License The P rogram below and a work based on the Program Program or any derivative work under copyright law a work containing the Program or a port ion of it either verbatim or with modifications and or translated into another on is included without limitation in language Hereinafter translati the term modification Each licensee is addressed as you Activities other than copying distribution and modification are
45. provided in Section 6 5 Defining and saving filters Zz Display Filters Analyze Display ES Filters This item brings up a dialog box that allows you to create and edit display filters You can name filters and you can save them for future use More detail on this subject is provided in Section 6 5 Defining and saving filters 54 User Interface Toolbar Toolbar Item Corresponding Description Icon Menu Item Coloring Rules View Coloring Rules This item brings up a dialog box that allows you color pack ets in the packet list pane according to filter expressions you choose It can be very useful for spotting certain types of packets More detail on this subject is provided in Sec tion 9 3 Packet colorization Preferences Edit Preferences This item brings up a dialog box that allows you to set prefer ences for many parameters that control Ethereal You can also save your preferences so Ethereal will use them the next time you start it More detail is provided in Section 9 5 Preferences Help Help Contents This item brings up help dialog box 55 User Interface 3 14 The Filter toolbar The filter toolbar lets you quickly edit and apply display filters More information on display filters is available in Section 6 2 Filtering packets while viewing Figure 3 12 The Filter toolbar PZ Eiter v dp Expression Y
46. stream See Section 3 10 The Analyze menu This menu contains menu items to display various statistic windows including a summary of the packets that have been captured display protocol hierarchy statist ics and much more See Section 3 11 The Statistics menu This menu contains items to help the user like access to some basic help a list of the supported protocols manual pages online access to some of the webpages and the usual about dialog See Section 3 12 The Help menu Each of these menu items is described in more detail in the sections that follow Tip You can access menu items directly or by pressing the corresponding accelerator keys which are shown at the right side of the menu For example you can press the Control or Strg in German and the K keys together to open the capture dialog 33 User Interface 3 5 The File menu The Ethereal file menu contains the fields shown in Table 3 1 File menu items Figure 3 3 The File Menu test cap Ethereal DER AAR Edit View Go Capture Analyze Statistics Help open wo b RADA Ft Raa Open Recent Merge X Close Ctrlew x 4 Expression Ys clear Apply Save ra Destination Protocol Info B save as Shift ctri s oe a i File Set jo 224 0 0 22 v3 Membership Report Ll as Plain Text file as PostScript file as CSV Comma Separated Values packet summary file
47. the capture data from e libpcap tcpdump e Novell LANalyzer e Network Associates Sniffer e Sun snoop e Microsoft Network Monitor e Visual Networks Visual UpTime traffic e Accellent 5Views e Networks Instruments Observer version 9 e HP UX s nettl E Other protocol analyzers may require that the file has a certain suffix in order to read the files you generate with Ethereal e g DMP for Tcpdump libpcap CAP for Network Associates Sniffer Windows 84 File Input Output and Printing 5 4 Merging capture files Sometimes you need to merge several capture files into one For example this can be useful if you have captured simultaneously from multiple interfaces at once e g using multiple instances of Eth ereal Merging capture files can be done in three ways e Use the menu item Merge from the File menu to open the merge dialog see Figure 5 3 The Merge with Capture File dialog box This menu item will be disabled until you have loaded a capture file e Use drag and drop to drop multiple files on the main window Ethereal will try to merge the packets in chronological order from the dropped files into a newly created temporary file If you drop only a single file it will simply replace a maybe existing one e Use the mergecap tool which is a command line tool to merge capture files This tool provides the most options to merge capture files see Section D 6 mergecap Merging multiple c
48. to ensure the integrity of data portions for data transmission or storage A checksum is basically a calculated summary of such a data portion Network data transmissions often produce errors such as toggled missing or duplicated bits As a result the data received might not be identical to the data transmitted which is obviously a bad thing Because of these transmission errors network protocols very often use checksums to detect such errors The transmitter will calculate a checksum of the data and transmits the data together with the checksum The receiver will calculate the checksum of the received data with the same algorithm as the transmitter If the received and calculated checksums don t match a transmission error has occured Some checksum algorithms are able to recover simple errors by calculating where the expected error must be and repairing it If there are errors that cannot be recovered the receiving side throws away the packet Depending on the network protocol this data loss is simply ignored or the sending side needs to detect this loss somehow and retransmits the required packet s Using a checksum drastically reduces the number of undetected transmission errors However the usual checksum algorithms cannot guarantee an error detection of 100 so a very small number of transmis sion errors may remain undetected There are several different kinds of checksum algorithms an example of an often used checksum al gori
49. under the GNU General Public Licence GPL All source code is freely available under the GPL You are welcome to modify Ethereal to suit your own needs and it would be appreciated if you contribute your improvements back to the Ethereal team You gain three benefits by contributing your improvements back to the community e Other people who find your contributions useful will appreciate them and you will know that you have helped people in the same way that the developers of Ethereal have helped people e The developers of Ethereal might improve your changes even more as there s always room for improvements Or they may implement some advanced things on top of your code which can be useful for yourself too e The maintainers and developers of Ethereal will maintain your code as well fixing it when API changes or other changes are made and generally keeping it in tune with what is happening with Ethereal So if Ethereal is updated which is done often you can get a new Ethereal version from the website and your changes will already be included without any effort for you The Ethereal source code and binary kits for some platforms are all available on the download page of the Ethereal website http www ethereal com download html Introduction 1 7 Reporting problems and getting help If you have problems or need help with Ethereal there are several places that may be of interest to you well beside this guide of course
50. upgraded to a new windows version your profile might be kept in the former location so the defaults mentioned here might not apply The following will try to guide you to the right place where to look for Ethereals profile data 170 Configuration and other Files and A 1 2 A 1 3 Folders 95 98 ME The default in Windows 95 98 ME is all users work with the same profile which is located at C windows Application Data Ethereal 98 ME with enabled user pro In Windows 98 and ME you can enable separate user profiles files In that case something like C windows Profiles lt username gt Applicatio n Data Ethereal is used NT 4 C WINNT Profiles lt username gt Application Data Ethereal 2000 XP C Documents and Set tings lt username gt Application Data Docu ments and Settings and Application Data might be interna tionalized Windows NT 2000 XP roaming profiles The following will only be applicable if you are using roaming profiles This might be the case if you work in a Windows domain environment used in huge company networks The configurations of all programs you use won t be saved on the local harddrive of the computer you are currently working on but on the domain server As Ethereal is using the correct places to store it s profile data your settings will travel with you if you logon to a different computer the next time There is an exception to this The Local Settings fo
51. what s going on at the network interfaces Ethereal knows of see Section 4 4 The Capture In terfaces dialog box Options Ctrl K This menu item brings up the Capture Options dialog box discussed fur ther in Section 4 5 The Capture Options dialog box and allows you to start capturing packets Start Immediately start capturing packets with the same settings than the last time Stop Ctrl E This menu item stops the currently running capture see Section 4 9 1 Stop the running capture Restart This menu item stops the currently running capture and starts again with the same options this is just for convenience 45 User Interface Menu Item Accelerator Description Capture Fil ters This menu item brings up a dialog box that allows you to create and edit capture filters You can name filters and you can save them for future use More detail on this subject is provided in Section 6 5 Defining and saving filters 46 User Interface 3 10 The Analyze menu The Ethereal Analyze menu contains the fields shown in Table 3 6 Analyze menu items Figure 3 8 The Analyze Menu test cap Ethereal DER File Edit Yiew Go Capture FEE Statistics Help Display Filters pares E E o a Ee ia Selected xz SB Q Q gt Not Selected Prepare a Filter w Filter and Selected bn Ygeclear Y Apply Enabled Proto
52. when merging mergecap assumes that packets within a capture file are already in chro nological order s__ Sets the snapshot length to use when writing the data w Sets the output filename T Sets the packet encapsulation type of the output capture file F Sets the file format of the output capture file A simple example merging dhcp capture libpcap and imap 1 libpcap into out file libpcap is shown below Example D 4 Simple example of using mergecap mergecap w outfile libpcap dhcp capture libpcap imap 1 libpcap 186 Related command line tools D 7 text2pcap Converting ASCII hexdumps to network captures There may be some occasions when you wish to convert a hex dump of some network traffic into a libpcap file Text2pcap is a program that reads in an ASCII hex dump and writes the data described into a libp cap style capture file text2pcap can read hexdumps with multiple packets in them and build a cap ture file of multiple packets text2pcap is also capable of generating dummy Ethernet IP and UDP headers in order to build fully processable packet dumps from hexdumps of application level data only Text2pcap understands a hexdump of the form generated by od t x1 In other words each byte is in dividually displayed and surrounded with a space Each line begins with an offset describing the po sition in the file The offset is a hex number can also be octal see o of more than two hex digits Here is a s
53. 1 0 200 OK onnection close Server UPnP 1 0 UPnP Device Host 1 0 imeout Second 1800 SID uuid cf Entire conversation 368 bytes v ASCII EBCDIC Hex Dump C Arrays O Raw Filter out this stream The stream content is displayed in the same sequence as it appeared on the network Traffic from A to B is marked in red while traffic from B to A is marked in blue If you like you can change these colors in the Edit Preferences Colors page None printable characters will be replaced by dots XXX What about line wrapping maximum 123 Advanced Topics line length and CRNL conversions The stream content won t be updated while doing a live capture To get the latest content you ll have to reopen the dialog You can choose from the following actions 1 Save As Save the stream data in the currently selected format 2 Print Print the stream data in the currently selected format 3 Direction Choose the stream direction to be displayed Entire conversation data from A to B only or data from B to A only 4 Filter out this stream Apply a display filter removing the current TCP stream data from the display 5 Close Close this dialog box leaving the current display filter in effect You can choose to view the data in one of the following formats 1 ASCII In this view you see the data from each direction in ASCII Obviously best for ASCII based protocols e g HTTP 2 EBCDIC For the big iron f
54. 1 274987 192 168 0 1 192 168 0 2 TCP http gt 3197 FIN ACK Seq 20 Ack 190 Win 3072Len 0 MBR Frame 36 60 bytes on wire 60 bytes captured Ethernet II Src O0 09 Sb 2d 75 9a Dst 00 0b 5d 20 cd 02 Internet Protocol Src Addr 192 168 0 1 192 168 0 1 Ost Addr 192 168 0 2 192 168 0 2 Transmission Control Protocol Src Port http 80 Ost Port 3197 3197 Seq 20 Ack 190 Len O0 00 Ob 5d 20 cd 02 00 09 Sb 2d 75 9a 08 OO 45 00 00 28 00 84 00 00 40 06 fe f3 cO ag 00 01 cO ag oo 02 METT 7d 00 00 68 14 3c 38 dd 9b 50 11 Cae 00 00 O00 00 00 00 Finally you can bring up a pop up menu over either the Packet List Packet Details or Packet Bytes pane by clicking your right mouse button The following table gives an overview which functions are available in the panes where to find the corresponding function in the menu and a short description of each item Table 6 1 Function overview of the pop up menus Item Lis De Byt Menu Description t tail Jes s Mark Packet X Edit toggle Mark a packet Time Reference X Edit Set reset and find time references Expand Subtrees X View Expand the currently selected subtree Expand All X J View Expand all subtrees in all packets in the capture Collapse All X J View Ethereal keeps a list of all the protocol subtrees that are expanded and uses it to ensure that the correct subtrees are expanded when y
55. 192 168 0 2 192 168 0 2 Transmission Control Protocol Src Port 1025 1025 Dst Port 5000 5000 Seq 1 Ack 1 Len O Sb 2d 75 9a Mu ac oo E Copy Export Selected Packet Bytes Type eth type 2 bytes P 120 D 120 M 0 A Ob Sd 20 cd 02 00 09 0010 00 28 00 7c OO OO 40 06 f9 OO cO ag 00 0020 00 02 04 01 13 88 OO OO 67 81 3c 37 7f 0030 Oc 00 e7 97 00 00 00 00 OO 00 OO 00 Copy Copy the selected packet data to the clipboard XXX in which format Export Selected Packet Bytes This menu item is the same as the File menu item of the same name It allows you to export raw packet bytes to a binary file 104 Working with captured packets 6 2 Filtering packets while viewing Ethereal has two filtering languages One used when capturing packets and one used when display ing packets In this section we explore that second type of filter Display filters The first one has already been dealt with in Section 4 8 Filtering while capturing Display filters allow you to concentrate on the packets you are interested in while hiding the cur rently uninteresting ones They allow you to select packets by e Protocol e The presence of a field e The values of fields e A comparison between fields e and a lot more To select packets based on protocol type simply type the protocol you are interested in in the Filter field in the filter toolbar of the Ethereal window and press enter t
56. A simple shell script wrapper that the end user should use to generate the dissector from the IDL file s Why do this It is important to understand what CORBA traffic looks like over GIOP IIOP and to help build a tool that can assist in troubleshooting CORBA interworking This was especially the case after see ing a lot of discussions about how particular IDL types are represented inside an octet stream I have also had comments feedback that this tool would be good for say a CORBA class when teaching students what CORBA traffic looks like on the wire It is also COOL to work on a great Open Source project such as the case with Ethereal ht tp www ethereal com How to use idl2eth To use the idl2eth to generate ethereal dissectors you need the following Prerequisites to using idl2eth 1 Python must be installed See http python org 2 omniidl from the the omniORB package must be available See http omniorb sourceforge net 3 Of course you need ethereal installed to compile the code and tweak it if required idl2eth is part of the standard Ethereal distribution To use idl2eth to generate an ethereal dissector from an idl file use the following procedure 190 Related command line tools Procedure for converting a Corba idl file into an ethereal dissector 1 To write the C code to stdout idl2eth lt your file idl gt eg idl2eth echo idl 2 To write to a file just redirect the output idl2eth echo
57. Ashok Narayanan from whose text2pcap man page Section D 7 text2pcap Converting ASCI hexdumps to network captures is derived e Frank Singleton from whose README idl2eth Section D 8 idl2eth Creating dissectors from Corba IDL files is derived Preface 4 About this document This book was originally developed by Richard Sharpe with funds provided from the Ethereal Fund It was updated by Ed Warnicke and more recently redesigned and updated by Ulf Lamping It is written in DocBook XML You will find some specially marked parts in this book 2 v This is a warning You should pay attention to a warning as otherwise data loss might occur This is a note A note will point you to common mistakes and things that might not be obvious This is a tip Tips will be helpful for your everyday work using Ethereal xi Preface 5 Where to get the latest copy of this document The latest copy of this documentation can always be found at http www ethereal com docs usersguide Preface 6 Providing feedback about this document Should you have any feedback about this document please send them to the authors through ethere al dev AT ethereal com xiii Preface xiv Chapter 1 Introduction 1 1 What is Ethereal 1 1 1 1 1 2 Ethereal is a network packet analyzer A network packet analyzer will try to capture network pack ets and tries t
58. E 97 6 Working with captured packets 20 0 0 eina ADEE R seca RE RE E REE Ene 99 6 1 Viewing packets you have captured eeesseeeseeerrseesrrrrsrrerrsrrerrsresrrrrerrrersrrerrereerreees 99 6 2 Filtering packets while Vie WING ss ss icc essees sbovendssebsnausshvostapecdssnassdedeodsenssousssssesnspeess 105 6 3 Building display filter expressions 2 0 0 0 0 cece cece cece eee a eeca ceca eenn cena eeneeeneeeneeeenes 107 6 3 1 Display filter fields sissien eisien sas bebe as seas E dee esata ah eee TANs 107 6 3 2 Comparing Values siseses eee anseres aerie beces et Duca ston ueedusth guarire e 107 6 3 3 Combining Expressions ssir pies nises aip o cosy sebeaagssedeacueesvtandssedsaess sevieoapeess 108 6 3 4 A common mistakes nsoro lend bendeas toes E a E E STEE gas Seen dass 110 6 4 The Filter Expression dialog Dox 20 0 0 nea n E a E E S ES 111 6 5 Defining and saving Titers is 3 c ucscges syerness tee E e EEES TE N E N E E E EE EEE 113 Ethereal User s Guide 6 6 Finding packets sson 5 sees rosee ess Ear bash RE EE EE E IRESE svete agp TOOS ESRR EE susateusess pte AROR 115 6 6 1 The Find Packet dialog Dox irssi eE a R EREA EESE N 115 6 6 2 The Find Next command Ssss poist ar EE E EE E E TE E 116 6 6 3 The Find Previous COMMANA sss eiaa E e i e A VRE ea 116 6 7 Go t a specific packet mn misora it e e tens r EE EEE EEEE S 117 6 7 1 The Go Back command neeese a dann E E E R e 117 6 7 2 The
59. ESA EE SE 140 SASEndpommts 22250 r a E sbadwa lan eieht yl eeediay Seeded sonic tomyieeg EE Sate ap eae meat 142 8 4 1 What asian Endpoint ceris te eaa e bt ede tenet cates EE aa deee sect 142 8 4 2 The Endpoints Window cccceeeceee cece ceceneceneceneceeeeeeeeeeeeeceaeeeaeseu scan eeaes 142 8 4 3 The protocol specific Endpoint List windows cee ceeeceeeceeeee teen eeee seen eenes 143 8 3 Conversations 4 22226 os ote e Ween cored eet eels Ee aE A EEE 144 85 15 What 18a Conversation is paccets er n e pateedetsateassaetethe sa aoaehas E a 144 8 5 2 The Conversations Window ceceseceecneceeceeeeeeeeesenereeeeereeeneeeseneresenereees 144 8 5 3 The protocol specific Conversation List Windows ceeceeeeeeeee teen teen eenes 144 8 0 The TO Graphs WindOw vo see 5 ig tabs eveusee Aaa deny tes hen sdes ova daws Satu daa Savedanse teeta E S 145 8 7 Service Response TIME serine ea eat na ede ee Noe a oe Fah es eae N ETET ESSE 147 8 7 1 The Service Response Time DCE RPC window ceceeeeeee eee eeeeeeeeeeeees 147 8 8 The protocol specific statistics WINCOWS ccceceeeeeeeeececeeeceueeeceeececueeeueeeeesceaueeeenees 149 9 Customizing Ethereal rsio ecens coe songs viedo seek a ed aewnyoen ae dabe gers swib debs lub laces Gortaeedebueder sen athe 151 O71 Introduction e ea ees eel e ence E E EE ee nek oad uaa cea eoucagesboe eae eet R 151 9 2 Start Ethereal from t
60. Ethereal User s Guide 18188 for Ethereal 0 10 14 Ulf Lamping Richard Sharpe NS Computer Software and Services P L Ed Warnicke Ethereal User s Guide 18188 for Ethereal 0 10 14 by Ulf Lamping Richard Sharpe and Ed Warnicke Copyright 2004 2005 Ulf Lamping Richard Sharpe Ed Warnicke Permission is granted to copy distribute and or modify this document under the terms of the GNU General Public License Version 2 or any later version published by the Free Software Foundation All logos and trademarks in this document are property of their respective owner Table of Contents PrefaCe 3 sissies iecds o tera a aa boeneos a leas Made ae E aa Pee daa bo e aS ented viii Ls FOTE WOT yeee 3250385 sss sote ae videaad es voted ea OESTE EE aE EEA ES REEE E ENESE SEESE TER ES wei viii 2 Who should read this document eseesseseesseresererrseesrrersrreresrrerreresrrrerrrreesrreererereeees ix 3 Acknowled tements Siis sinin ee e EE EA anatase E EEEE ERE X 4 About this document 22 5 vec ccs eee cesta ccceseytec cesses ooo EEI EIEEE EEEE E EnS xi 5 Where to get the latest copy of this document 20 0 0 cece cece cece ecenecce cena eeneeeneeennees xii 6 Providing feedback about this document essesssseersseesreeresreresrrsrrererrrrrerrerrsrrerrsreseent xiii Tantrod ction s aa n a A E eg E a ate MS a 1 Tl Whatis Ethereal esensi nepe stan ss oh oS E A E AE AE E N AOE NE OS ES 1 1 1 1 Some intended purpo
61. Expression dialog box is an excellent way to learn how to write Ethereal display filter strings Figure 6 7 The Filter Expression dialog box Ethereal Filter Expression Field name Relation 3GPP2 411 802 11 MGT 802 11 Radiotap AALL AAL3 4 AARP ACAP ACN ACSE AFP AFS RX 4H AIM AIM Administration AIM Advertisements H AIM BOS E E E E When you first bring up the Filter Expression dialog box you are shown a tree list of field names organized by protocol and a box for selecting a relation Field Name Select a protocol field from the protocol field tree Every protocol with filterable fields is listed at the top level By clicking on the next to a protocol name you can get a list of the field names available for filtering for that protocol Relation Select a relation from the list of available relation The is present is a unary rela tion which is true if the selected field is present in a packet All other listed rela tions are binary relations which require additional data e g a Value to match to complete When you select a field from the field name list and select a binary relation such as the equality re lation you will be given the opportunity to enter a value and possibly some range information 111 Working with captured packets Value Predefined values Range OK Cancel You may enter an appropriate value in the Value text box The Value wi
62. Menu Item Accelerator Description Reload Ctrl R This menu item allows you to reload the current capture file 42 User Interface 3 8 The Go menu The Ethereal Go menu contains the fields shown in Table 3 4 Go menu items Figure 3 6 The Go Menu test cap Ethereal DER File Edit view Eei Capture Analyze Statistics Help Bi Qge sxPFLGaa Ctrl G i 4 Expression Yi gear yf Apply AA Protocol Info ARP who has ratui tous 4 0 726445 192 168 0 2 224 0 0 22 IGMP V3 Membership Report Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O0 0b S5d 20 cd 02 Ost Broadcast ff ff ff ff ff fh Address Resolution Protocol request gratuitous ARP oooo ff ff ff ff ff TT OO Ob Sd 20 cd 02 08 06 OO 01 0010 08 OO 06 04 00 01 00 Ob Sd 20 cd 02 cO ag 00 02 0020 00 00 OO OO 00 OO cO as 00 02 File Opes test cap 14 KB 00 00 02 P 120 D 120 M 0 Table 3 4 Go menu items Menu Item Accelerator Description Back Alt Left Jump to the recently visited packet in the packet history much like the page history in a web browser Forward Alt Right Jump to the next visited packet in the packet history much like the page history in a web browser Go to Packet Ctrl G Bring up a dialog box that allows you to specify a packet number and then goes to that packet See Section 6 7 Go to a specific packet for details Go to Corr
63. Nanoseconds The timestamp precision will be forced to the given setting If the actually available precision is smaller zeros will be appended If the precision is larger the remaining decimal places will be cut off Precision example If you have a timestamp and it s displayed using Seconds Since Previous Pack et the value might be 1 123456 This will be displayed using the Automatic setting for libpcap files which is microseconds If you use Seconds it would show simply 1 and if you use Nano seconds it shows 1 123456000 Packet time referencing The user can set time references to packets A time reference is the starting point for all subsequent packet time calculations It will be useful if you want to see the time values relative to a special packet e g the start of a new request It s possible to set multiple time references in the capture file A Warning The time references will not be saved permanently and will be lost when you close the capture file Note Time referencing will only be useful if the time display format is set to Seconds Since Beginning of Capture If one of the other time display formats are used time referencing will have no effect and will make no sense either To work with time references choose one of the Time Reference items in the Edit menu see 119 Working with captured packets Section 3 6 The Edit menu or from the pop up menu of the Packet List pane
64. Seba ese slat EEEE ES EEEE N EE deeks Sousesiete pees 10 DET 2g WAKA ee Sees hos oaeen aer Ep ag foe Ea ORE O EEEE EEES SEARES S PES SOSE EEOSE 10 L73 FAQ a et enoe a E EE EEEE ASE EEEn S SEEE EE E TS 10 74s Marling Lasts a s a chose Re E A OE A A 10 L275 REPOrungE Problems ryano a ogee sumgsetovaeeseshwanssnheSateepemass cused ete hs wan sen 11 1 7 6 Reporting Crashes on UNIX Linux platforms 0c ee cece eee eeeneeeneeennees 11 1 7 7 Reporting Crashes on Windows platforms c cee ceeeeeeecneece cece eeneeeneeeneeeenees 12 2 Building and Installing Ethereal siorse iin iin T E e E E T E E EEE 14 2 1 mtrod ct on e e eA e oea a RE E EEE A ensue ER ERS EEE EAEE ESES EE 14 2 2 Obtaining the source and binary distributions ssesessessseesersrssrrrrsrrerrsrrerreresreresreeees 15 2 3 Before you build Ethereal under UNIX ssc ocioso dsrin aieri Des 16 2 4 Building Ethereal from source under UNIX 000 0 ee cece eee ceeece seen eeeaeesa sean een eeae 19 2 5 Installing the binaries under UNIX 0000 ieee eee cceecc ence raS O es Ga rerea EE KOTSE Epa VEES 21 2 5 1 Installing from rpm s under RedHat and alike 2 0 0 0 cece ceee en eeee eee eene eens 21 2 5 2 Installing from deb s under Debian 0 ee cee cee ceeeceeeeeeeeaeeea sean eeaeeees 21 2 6 Troubleshooting during the install on Unix cece cence ee ceeeeeeeeaeceaeena eens eeaeees 22 2 7 Building from source under Windows esse eecee
65. The Ethereal menu sits on top of the Ethereal window An example is shown in Figure 3 2 The Menu Note Menu items will be greyed out if the corresponding feature isn t available For ex ample you cannot save a capture file if you didn t capture or load any data before Figure 3 2 The Menu File Edit View Go Capture Analyze Statistics Help It contains the following items File Edit View Go Capture Analyze Statistics Help This menu contains items to open and merge capture files save print export capture files in whole or in part and to quit from Ethereal See Section 3 5 The File menu This menu contains items to find a packet time reference or mark one or more packets set your preferences cut copy and paste are not presently implemented See Section 3 6 The Edit menu This menu controls the display of the captured data including the colorization of packets zooming the font show a packet in a separate window expand and col lapse trees in packet details See Section 3 7 The View menu This menu contains items to go to a specific packet See Section 3 8 The Go menu This menu allows you to start and stop captures and to edit capture filters See Sec tion 3 9 The Capture menu This menu contains items to manipulate display filters enable or disable the dis section of protocols configure user specified decodes and follow a TCP
66. a libpcap style capture file Mergecap Mergecap is a program that combines multiple saved capture files into a single out put file Capinfos Capinfos is a program that provides information on capture files The Additional Tasks Start Menu Shortcuts add some start menu shortcuts Desktop Icon add an Ethereal icon to the desktop Quick Launch Icon add an Ethereal icon to the Explorer quick launch toolbar Associate file extensions to Ethereal Associate standard network trace files to Ethereal Install WinPcap Note As mentioned above the Ethereal installer since version 0 10 12 takes care of the installation of WinPcap so usually you don t have to worry about WinPcap at all If you do not have WinPcap installed you will be able to open saved capture files but you will not be able to capture live network traffic While running the Ethereal installer detects which WinPcap version is currently installed and will 25 Building and Installing Ethereal install WinPcap if none or an older version is detected More WinPcap info e Ethereal related http wiki ethereal com WinPcap e General WinPcap info http www winpcap org 2 8 2 1 Manual WinPcap Installation 2 8 3 2 8 4 2 8 5 The following is only necessary if you want to try a different version than the one included in the Ethereal installer e g because a new WinPcap beta version was released Additional WinPcap versions includ
67. a binary if you have downloaded the source This may involve building and or installing other necessary packages 3 Install the binaries into their final destinations Building and Installing Ethereal 2 2 Obtaining the source and binary distributions You can obtain both source and binary distributions from the Ethereal web site ht tp www ethereal com Simply select the download link and then select either the source package or binary package of your choice from the mirror site closest to you E Download all required files In general unless you have already downloaded Ethereal before you will most likely need to download several source packages if you are building Ethereal from source This is covered in more detail below Once you have downloaded the relevant files you can go on to the next step Note While you will find a number of binary packages available on the Ethereal web site you might not find one for your platform and they often tend to be several versions behind the current released version as they are contributed by people who have the platforms they are built for For this reason you might want to pull down the source distribution and build it as the process is relatively simple Building and Installing Ethereal 2 3 Before you build Ethereal under UNIX Before you build Ethereal from sources or install a binary package you must ensure that you have the following other packages inst
68. ach row contains the statistical values of one protocol The following columns containing the statistical values are available e Protocol this protocol s name e Packets the percentage of protocol packets relative to all packets in the capture e Packets the absolute number of packets of this protocol e Bytes the absolute number of bytes of this protocol e MBit s the bandwidth of this protocol relative to the capture time e End Packets the absolute number of packets of this protocol where this protocol were the highest protocol to decode e End Bytes the absolute number of bytes of this protocol where this protocol were the highest protocol to decode e End MBit s the bandwidth of this protocol relative to the capture time where this protocol were the highest protocol to decode 140 Statistics I WW Note Packets will usually contain multiple protocols so more than one protocol will be counted for each packet Example In the screenshot IP has 99 17 and TCP 85 83 which is together much more than 100 Note A single packet can contain the same protocol more than once In this case the pro tocol is counted more than once For example in some tunneling configurations the IP layer can appear twice 141 Statistics 8 4 Endpoints 8 4 1 8 4 2 Statistics of the endpoints captured Tip If you are looking for a feature other network tools call a hostlist here is the right place
69. affic except that from 10 0 0 5 Example 4 2 Capturing all telnet traffic not from 10 0 0 5 tcp port 23 and not host 10 0 0 5 XXX add examples to the following list A primitive is simply one of the following srcldst host lt host gt This primitive allows you to filter on a host IP address or name You can optionally precede the primitive with the keyword srcldst to specify that you are only interested in source or destination addresses If these are not present pack ets where the specified address appears as either the source or the destination address will be selected ether srcldst host lt ehost gt This primitive allows you to filter on Ethernet host addresses 73 Capturing Live Network Data gateway host lt host gt srcldst net lt net gt mask lt mask gt l len lt len gt tcpludp srcldst port lt port gt lesslgreater lt length gt iplether proto lt protocol gt etherlip broadcastlmulticast lt expr gt relop lt expr gt You can optionally include the keyword srcldst between the keywords ether and host to specify that you are only inter ested in source or destination addresses If these are not present packets where the specified address appears in either the source or destination address will be selected This primitive allows you to filter on packets that used host as a gateway That is where the Ethernet source or destina tion was host but neither the source nor destin
70. agents Endace Measurement Systems ERF format captures Linux Bluez Bluetooth stack hcidump w traces Catapult DCT2000 out files Note It may not be possible to read some formats dependent on the packet types captured Ethernet captures are usually supported for most file formats but other packet types e g token ring packets may not be possible to read from all file formats 81 File Input Output and Printing 5 3 Saving captured packets You can save captured packets simply by using the Save As menu item from the File menu under Ethereal You can choose which packets to save and which file format to be used 5 3 1 The Save Capture File As dialog box The Save Capture File As dialog box allows you to save the current capture to a file Figure 5 2 The Save Capture File As dialog box shows an example of this dialog box Note Ethereal uses the open dialog box from the version of the GTK toolkit that it s using This dialog was completely redesigned in the GTK version 2 4 Depending on the in stalled GTK version your dialog box might look different However as the functional ity remains almost the same much of this description will work with your version of Ethereal Figure 5 2 The Save Capture File As dialog box 82 File Input Output and Printing Ethereal Save Capture File As Mame Save in folder 5 D Facket Range All packets 120 120 Selected packet only 1 ar
71. al D described above a number as reported by ethereal D can also be used If you re using UNIX net stat i or ifconfig a might also work to list interface names although not all versions of UNIX support the a flag to if config If no interface is specified Ethereal searches the list of inter faces choosing the first non loopback interface if there are any non loopback interfaces and choosing the first loopback interface if there are no non loopback interfaces if there are no interfaces Ethereal reports an error and doesn t start the capture Pipe names should be either the name of a FIFO named pipe or to read data from the standard input Data read from pipes must be in standard libpcap format k The k option specifies that Ethereal should start capturing packets immediately This option requires the use of the i parameter to specify the interface that packet capture will oc cur from l This option turns on automatic scrolling if the packet list pane is being updated automatically as packets arrive during a cap ture as specified by the S flag L List the data link types supported by the interface and exit m lt font gt This option sets the name of the font used for most text dis played by Ethereal XXX add an example n Disable network object name resolution such as hostname TCP and UDP port names N lt name resolving flags gt Turns on name resolving for particular types of addresses and
72. al times be displayed for all packets e ad absolute with date which specifies that actual dates and times be displayed for all packets e d delta which specifies that timestamps are relative to the previous packet y The v option requests Ethereal to print out its version in formation and exit w lt savefile gt This option sets the name of the savefile to be used when sav ing a capture file y lt capture link type gt If a capture is started from the command line with k set the data link type to use while capturing packets The values re ported by L are the values that can be used 155 Customizing Ethereal X lt eXtension option gt Specify an option to be passed to a Tethereal module The eXtension option is in the form extension_key value where extension_key can be lua_script lua_script_filename Tell Ethereal to load the given script in addition to the default Lua scripts Z lt statistics string gt Get Ethereal to collect various types of statistics and display the result in a window that updates in semi real time XXX add more details here 156 Customizing Ethereal 9 3 Packet colorization A very useful mechanism available in Ethereal is packet colorization You can set up Ethereal so that it will colorize packets according to a filter This allows you to emphasize the packets you are usually interested in Tip You will find a lot of Coloring Rule examples at the Ethereal W
73. alled e GTK The GIMP Tool Kit You will also need Glib Both can be obtained from www gtk org e libpcap the packet capture software that Ethereal uses You can obtain libpcap from www tcpdump org Depending on your system you may be able to install these from binaries e g RPMs or you may need to obtain them in source code form and build them If you have downloaded the source for GTK the instructions shown in Example 2 1 Building GTK from source may provide some help in building it Example 2 1 Building GTK from source gzip de gtk 1 2 10 tar gz tar xvf lt much output removed gt cd gtk 1 2 10 configure lt much output removed gt make lt much output removed gt make install lt much output removed gt Note You may need to change the version number of gtk in Example 2 1 Building GTK from source to match the version of GTK you have downloaded The directory you change to will change if the version of GTK changes and in all cases tar xvf will show you the name of the directory you should change to Note If you use Linux or have GNU tar installed you can use tar zxvf gtk 1 2 10 tar gz It is also possible to use gunzip c or gzcat rather than gzip dc on many UNIX sys tems Note If you downloaded gtk or any other tar file using Windows you may find your file called gtk 1_2 8 tar gz You should consult the GTK web site if any errors occ
74. ample dump that text2pcap can recognize 000000 00 e0 le a7 05 6f 00 10 000008 5a a0 b9 12 08 00 46 00 000010 03 68 00 00 00 00 Oa 2e 00001 8 ee 33 OF 19 08 TE OF S19 as arses 000020 03 80 94 04 00 00 10 O1 000028 16 a2 Oa 00 03 50 00 Oc 000 030 01 OL OF rr 03 280 DOU ara aos There is no limit on the width or number of bytes per line Also the text dump at the end of the line is ignored Bytes hex numbers can be uppercase or lowercase Any text before the offset is ignored including email forwarding characters gt Any lines of text between the bytestring lines is ignored The offsets are used to track the bytes so offsets must be correct Any line which has only bytes without a leading offset is ignored An offset is recognized as being a hex number longer than two characters Any text after the bytes is ignored e g the character dump Any hex numbers in this text are also ignored An offset of zero is indicative of starting a new packet so a single text file with a series of hexdumps can be converted into a packet capture with multiple packets Multiple packets are read in with timestamps differing by one second each In general short of these restric tions text2pcap is pretty liberal about reading in hexdumps and has been tested with a variety of mangled outputs including being forwarded through email multiple times with limited line wrap etc There are a couple of other spe
75. apture files into one 5 4 1 The Merge with Capture File dialog box This dialog box let you select a file to be merged into the currently loaded file Note If your current data wasn t saved before you will be asked to save it first before this dialog box is shown Figure 5 3 The Merge with Capture File dialog box 85 File Input Output and Printing Ethereal Merge with Capture File BER Name TS AALL LLL Aa TTO F ee a test cap ap fc teetftrpreem i r Filename test cap I Filter Format libpcap tcpdump Ethereal etc Prepend packets to existing file Size 15317 bytes Packets 120 First Packet 2004 06 22 20 02 48 Elapsed time 00 00 02 Merge packets chronologically Append packets to existing file Prepend packets to existing file Prepend the packets from the selected file before the currently loaded packets Merge packets chronologically Merge both the packets from the selected and currently loaded file in chronological order Append packets to existing file Append the packets from the selected file after the currently loaded packets All other controls will work the same way as in the Open Capture File dialog box see Sec tion 5 2 1 The Open Capture File dialog box 86 File Input Output and Printing 5 5 File Sets When using the Multiple Files option while doing a capture see Section 4 6 Capture files and file mode
76. aptured packets to statistics about specific protocols e g statistics about the number of HTTP re quests and responses captured e General statistics e Summary about the capture file e Protocol Hierarchy of the captured packets e Endpoints e g traffic to and from an IP addresses e Conversations e g traffic between specific IP addresses e IO Graphs visualizing the number of packets or similar in time e Protocol specific statistics e Service Response Time between request and response of some protocols e Various other protocol specific statistics Note The protocol specific statistics requires detailed knowledge about the specific protocol Unless you are familiar with that protocol statistics about it will be pretty hard to un derstand 137 Statistics 8 2 The Summary window General statistics about the current capture file Figure 8 1 The Summary window Ethereal Summary File Mame D test cap Length 15317 bytes Format libpcap tcpdump Ethereal etc Packet size limit 65535 bytes Time First packet 2004 06 22 20 02 48 Lask packet 2004 06 22 20 02 50 Elapsed 00 00 02 Display Display Filter Marked packets Traffic Captured Displayed Between first and last packet 2 113 sec Packets 120 Avg packets sec 56 759 Avg packet size 111 442 bytes Bytes 13373 Avg bykesjsec 6326 662 Avg MBitisec 0 051 138 Statistics File general information about the
77. apturing on interface eth0 more details can be found at Section 9 2 Start Ethereal from the command line 64 Capturing Live Network Data 4 4 The Capture Interfaces dialog box When you select Interfaces from the Capture menu Ethereal pops up the Capture Interfaces dialog box as shown in Figure 4 1 The Capture Interfaces dialog box A Warning As the Capture Interfaces dialog is showing live captured data it is consuming a lot of system ressources Close this dialog as soon as possible to prevent excessive system load Note This dialog box will only show the local interfaces Ethereal knows of As Ethereal might not be able to detect all local interfaces and it cannot detect the remote inter faces available there could be more capture interfaces available than listed Figure 4 1 The Capture Interfaces dialog box Ethereal Capture Interfaces Description Packets Packets s Generic Ndiswan adapter Realtek RTL8139 810x Family Fast Ethernet NIC TUT Description The interface description provided by the operating system IP The first IP address Ethereal could resolve from this interface If no address could be resolved e g no DHCP server available unknown will be displayed If more than one IP address could be resolved only the first is shown unpredictable which one in that case Packets The number of packets captured from this interface since this dialog was opened W
78. are of this Uninstall Ethereal You can uninstall Ethereal the usual way using the Add or Remove Programs option inside the Control Panel Select the Ethereal entry to start the uninstallation procedure The Ethereal uninstaller will provide several options which things to be uninstalled the default is to remove the core components but keep the personal settings WinPcap and alike WinPcap won t be uninstalled by default as other programs than Ethereal may use it as well 26 Building and Installing Ethereal 2 8 6 Uninstall WinPcap You can uninstall WinPcap independantly of Ethereal using the WinPcap entry in the Add or Remove Programs of the Control Panel Note After uninstallation of WinPcap you can t capture anything with Ethereal It might be a good idea to reboot Windows afterwards 27 Building and Installing Ethereal 28 Chapter 3 User Interface 3 1 Introduction By now you have installed Ethereal and are most likely keen to get started capturing your first pack ets In the next chapters we will explore e How the Ethereal user interface works e How to capture packets in Ethereal e How to view packets in Ethereal e How to filter packets in Ethereal e and many other things 29 User Interface 3 2 Start Ethereal You can start Ethereal from your shell or window manager v J Tip When starting Ethereal it s possible to specify optional settings
79. arks the currently selected packet See Section 6 8 Marking packets for details Mark All Pack ets This menu item marks all packets Unmark All Packets This menu item unmarks all marked packets Preferences Shift Ctrl P This menu item brings up a dialog box that allows you to set preferences for many parameters that control Ethereal You can also save your prefer ences so Ethereal will use them the next time you start it More detail is provided in Section 9 5 Preferences 38 User Interface 3 7 The View menu The Ethereal View menu contains the fields shown in Table 3 3 View menu items Figure 3 5 The View Menu test cap Ethereal DER File Edit SJA Go Capture Analyze Statistics Help F 7 Main Toolbar I i P Eilter Toolbar 8 a gt 5D a 2 B Q Q E Statusbar Filter v Expression Clear Apply Packet List no i Packet Details Destination Protocol Info 1i Packet Bytes IEEE ARP Who ha B aE ratuitous Time Display Format Date and Time of Day 1970 01 01 01 02 03 123456 Name Resolution Time of Day 01 02 03 123456 Colorize Packet List Seconds Since Beginning of Capture 123 123456 Auto Scroll in Live Capture Seconds Since Previous Packet 1 123456 OF Zoom In Ctrl Automatic File Format Precision Q Zoom out Chri Seconds 0 Qu Isi Ctl Deciseconds 0 1 ee di Centiseconds 0 12 E Resize All Columns Miliseconds 0 123 E r
80. ation IP address was host This primitive allows you to filter on network numbers You can optionally precede this primitive with the keyword srcldst to specify that you are only interested in a source or destination network If neither of these are present packets will be selected that have the specified network in either the source or destination address In addition you can specify either the netmask or the CIDR prefix for the network if they are different from your own This primitive allows you to filter on TCP and UDP port numbers You can optionally precede this primitive with the keywords sreldst and tepludp which allow you to specify that you are only interested in source or destination ports and TCP or UDP packets respectively The keywords tepludp must ap pear before srcldst If these are not specified packets will be selected for both the TCP and UDP protocols and when the specified address ap pears in either the source or destination port field This primitive allows you to filter on packets whose length was less than or equal to the specified length or greater than or equal to the specified length respectively This primitive allows you to filter on the specified protocol at either the Ethernet layer or the IP layer This primitive allows you to filter on either Ethernet or IP broadcasts or multicasts This primitive allows you to create complex filter expressions that select bytes or ranges of bytes in packets Pl
81. ber When you press OK Ethereal will jump to that packet The Go to Corresponding Packet command If a protocol field is selected which points to another packet in the capture file this command will jump to that packet Note As these protocol fields now work like links just as in your Web browser it s easier to simply double click on the field to jump to the corresponding field The Go to First Packet command This command will simply jump to the first packet displayed The Go to Last Packet command This command will simply jump to the last packet displayed 117 Working with captured packets 6 8 Marking packets You can mark packets in the Packet List pane A marked packet will be shown with black back ground regardless of the coloring rules set Marking a packet can be useful to find it later while ana lyzing in a large capture file A Warning The packet marks are not stored in the capture file or anywhere else so all packet marks will be lost if you close the capture file You can use packet marking to control the output of packets when saving exporting printing To do so an option in the packet range is available see Section 5 8 The Packet Range frame There are three functions to manipulate the marked state of a packet e Mark packet toggle toggles the marked state of a single packet e Mark all packets set the mark state of all packets e Unmark all packets reset the mark state of a
82. bled data in the last packet of the chunk An example Ina HTTP GET response the requested data e g a HTML page is returned Ethereal will show the hex dump of the data in a new tab Uncompressed entity body in the Packet Bytes pane Reassembling is enabled in the preferences by default The defaults were changed from disabled to enabled in September 2005 If you created your preference settings before this date you might look if reassembling is actually enabled as it can be extremely helpful while analyzing network packets The enabling or disabling of the reassemble settings of a protocol typically requires two things 1 the lower level protocol e g TCP must support reassembly Often this reassembly can be en abled or disabled via the protocol preferences 130 Advanced Topics 2 the higher level protocol e g HTTP must use the reassembly mechanism to reassemble frag mented protocol data This too can often be enabled or disabled via the protocol preferences The tooltip of the higher level protocol setting will note you if and which lower level protocol set ting has to be considered too 131 Advanced Topics 7 6 Name Resolution 7 6 1 7 6 2 Name resolution tries to resolve some of the numerical address values into a human readable format There are two possible ways to do this conversations depending on the resolution to be done call ing system network services like the gethostname function
83. box 157 Customizing Ethereal Ethereal Edit Color Filter Filter Name arp Display Colors Foreground Color Background Color In the Edit Color dialog box simply enter a name for the color filter and enter a filter string in the Filter text field Figure 9 2 The Edit Color Filter dialog box shows the values arp and arp which means that the name of the color filter is arp and the filter will select protocols of type arp Once you have entered these values you can choose a foreground and background color for packets that match the filter expression Click on Foreground color or Background color to achieve this and Ethereal will pop up the Choose foreground background color for protocol dialog box as shown in Figure 9 3 The Choose color dialog box Figure 9 3 The Choose color dialog box Ethereal Choose background color for arp A Hue 214 Red 214 Saturation 16 Green 231 Value 100 y Blue 255 Color Name D6E7FF Select the color you desire for the selected packets and click on OK Note You must select a color in the colorbar next to the colorwheel to load values into the RGB values Alternatively you can set the values to select the color you want 158 Customizing Ethereal Figure 9 4 Using color filters with Ethereal shows an example of several color filters being used in Ethereal You may not like
84. bytes of data t time adjustment Specifies the time adjustment to be applied to selected pack ets infile This parameter specifies the input file to use It must be present outfile This parameter specifies the output file to use It must be present record record This optional parameter specifies the records to include or ex clude depending on the r option You can specify individual records or a range of records 183 Related command line tools D 6 mergecap Merging multiple capture files into one Mergecap is a program that combines multiple saved capture files into a single output file specified by the w argument Mergecap knows how to read libpcap capture files including those of tcpdump In addition Mergecap can read capture files from snoop including Shomiti and atmsnoop LanA lyzer Sniffer compressed or uncompressed Microsoft Network Monitor AIX s iptrace NetXray Sniffer Pro RADCOM s WAN LAN analyzer Lucent Ascend router debug output HP UX s nettl and the dump output from Toshiba s ISDN routers There is no need to tell Mergecap what type of file you are reading it will determine the file type by itself Mergecap is also capable of reading any of these file formats if they are compressed using gzip Mergecap recognizes this directly from the file the gz extension is not required for this purpose By default it writes the capture file in libpcap format and writes all of the pack
85. cap 14 KB 00 00 02 P 120 D 120 M 0 Ethereal s main window consist of parts that are commonly known from many other GUI programs 1 The menu see Section 3 4 The Menu is used to start actions 2 The main toolbar see Section 3 13 The Main toolbar provides quick access to frequently used items from the menu 3 The filter toolbar see Section 3 14 The Filter toolbar provides a way to directly manipu late the currently used display filter see Section 6 2 Filtering packets while viewing 4 The packet list pane see Section 3 15 The Packet List pane displays a summary of each packet captured By clicking on packets in this pane you control what is displayed in the other two panes 5 The packet details pane see Section 3 16 The Packet Details pane displays the packet se lected in the packet list pane in more detail 6 The packet bytes pane see Section 3 17 The Packet Bytes pane displays the data from the packet selected in the packet list pane and highlights the field selected in the packet details pane 7 The statusbar see Section 3 18 The Statusbar shows some detailed information about the 31 User Interface current program state and the captured data Tip The layout of the main window can be customized by changing preference settings See Section 9 5 Preferences for details 32 User Interface 3 4 The Menu
86. captured select DOCSIS otherwise select Ethernet 72 Capturing Live Network Data 4 8 Filtering while capturing Ethereal uses the libpcap filter language for capture filters This is explained in the tcpdump man page which can be hard to understand so it s explained here to some extent Tip You will find a lot of Capture Filter examples at ht tp wiki ethereal com CaptureFilters You enter the capture filter into the Filter field of the Ethereal Capture Options dialog box as shown in Figure 4 2 The Capture Options dialog box The following is an outline of the syntax of the tcpdump capture filter language See the expression option at the tcpdump manual page for details http www tcpdump org tcpdump_man html A capture filter takes the form of a series of primitive expressions connected by conjunctions and or and optionally preceded by not not primitive and or not primitive An example is shown in Example 4 1 A capture filter for telnet than captures traffic to and from a particular host Example 4 1 A capture filter for telnet than captures traffic to and from a particular host tcp port 23 and host 10 0 0 5 This example captures telnet traffic to and from the host 10 0 0 5 and shows how to use two primit ives and the and conjunction Another example is shown in Example 4 2 Capturing all telnet traffic not from 10 0 0 5 and shows how to capture all telnet tr
87. ces In addition to its native file format libpcap format also used by tcpdump WinDump and other libp cap WinPcap based programs Ethereal can read capture files from a large number of other packet capture programs as well See Section 5 2 2 Input File Formats for the list of capture formats Eth ereal understands The Open Capture File dialog box The Open Capture File dialog box allows you to search for a capture file containing previously captured packets for display in Ethereal Figure 5 1 The Open Capture File Dialog box shows an example of the Ethereal Open File Dialog box Note Ethereal uses the open dialog box from the version of the GTK toolkit that it s using This dialog was completely redesigned in GTK version 2 4 Depending on the installed GTK version your dialog box might look different However as the functionality re mains almost the same much of this description will work with your version of Ether eal Figure 5 1 The Open Capture File Dialog box 79 File Input Output and Printing Ethereal Open Capture File y Modified E system c 25 05 2004 o LA 10 03 2004 OE om 10 03 2004 e s Montag 02 05 2004 17 09 2003 01 06 2004 22 03 2004 29 10 2003 Today Today a e oe owe om Today oy Tas or c oy Today D mom Filename 250000 700 cap iiti Format libpcap tcpdump Ethereal etc Enable MAC name resolution Size 138665 bytes Packets 700 Fi
88. cial features to note Any line where the first non whitespace charac ter is will be ignored as a comment Any line beginning with TEXT2PCAP is a directive and options can be inserted after this command to be processed by text2pcap Currently there are no dir ectives implemented in the future these may be used to give more fine grained control on the dump and the way it should be processed e g timestamps encapsulation type etc Text2pcap also allows the user to read in dumps of application level data by inserting dummy L2 L3 and L4 headers before each packet The user can elect to insert Ethernet headers Ethernet and IP or Ethernet IP and UDP headers before each packet This allows Ethereal or any other full packet decoder to handle these dumps Example D 5 Help information available for text2pcap text2pcap exe h Usage text2pcap exe h d q o hlo l typenum e 13pid i proto m max packet u srcp destp T srcp destp s srcp destp tag S srcep destp tag t timefmt lt input filename gt lt output filename gt 187 Related command line tools where lt input filename gt specifies input filename use for standard input lt output filename gt specifies output filename use for standard output options are one or more of the following h Display this help message q Generate detailed debug of parser states o hex oct Parse offse
89. ciates Sniffer DOS based snoop Sun snoop netmonl Microsoft Network Monitor 1 x netmon2 Microsoft Network Monitor 2 x ngwsniffer_1_1 Network Associates Sniffer Windows based 1 1 ngwsniffer_2_0 Network Associates Sniffer Windows based 2 00x nettl HP UX nettl trace visual Visual Networks traffic capture 5views Accellent 5Views capture niobserverv9 Network Instruments Observer version 9 default is libpcap h produces this help listing r specifies that the records specified should be kept not deleted default is to delete s lt snaplen gt specifies that packets should be truncated to lt snaplen gt bytes of data t lt time adjustment gt specifies the time adjustment to be applied to selected packets T lt encap type gt specifies th ncapsulation type to use ther Ethernet tr Token Ring slip SLIP ppp PPP fddi FDDI fddi swapped FDDI with bit swapped MAC addresses l Hy Li s rawip Raw IP arcnet ARCNET arcnet_linux Linux ARCNET atm rfc1483 RFC 1483 ATM linux atm clip Linux ATM CLIP lapb LAPB atm pdus ATM PDUs atm pdus untruncated ATM PDUs untruncated null NULL ascend Lucent Ascend access equipment isdn ISDN ip over fc RFC 2625 IP over Fibre Channel pep with direction PPP with Directional Info ieee 802 11 IEEE 802 11 Wireless LAN prism IEEE 802 11 plus Prism II monitor mode header jeee 802 11
90. cket data to The Packet Range frame is described in Section 5 8 The Packet Range frame There s no such thing as a packet details frame for PSML export as the packet format is defined by the PSML specification 5 6 5 The Export as PDML File dialog box Export packet data into PDML This is an XML based format including the packet details The PDML file specification is available at PDML specification The PDML specification is not officially released and Ethereal s implementation of it is still in an early beta state so please expect changes in future Ethereal versions Figure 5 8 The Export as PDML File dialog box 91 File Input Output and Printing All packets Selected packet only Marked packets only From First Eo last marked packet gt Specify a packet range Oo e Export to file frame chooses the file to export the packet data to e The Packet Range frame is described in Section 5 8 The Packet Range frame There s no such thing as a packet details frame for PDML export as the packet format is defined by the PDML specification 5 6 6 The Export selected packet bytes dialog box Export the bytes selected in the Packet Bytes pane into a raw binary file Figure 5 9 The Export Selected Packet Bytes dialog box 92 File Input Output and Printing Ethereal Export Selected Packet Bytes mB Mame Save in folder e Debug_GTK2 Will save 28 byt
91. cols Shift Ctrl R a oF Selected No Time Source 3 Decode As and not Selected EM 33 User Specified Decades of not Selected Membership Report Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O0 0b Sd 20 cd 02 Ost Broadcast ff ff ff ff ff tt Address Resolution Pro 3 Crequest gratuitous ARP oooo ff Tt ff Tf Tf Tf 00 Ob Sd 20 cd 02 03 OG Muif ii 0s 00 06 04 00 01 00 Ob Sd 20 cd 02 cO as 00 02 o0 00 00 00 00 00 cO ag address Resolution Protocol arp 28 bytes P 120 D 120M 0 Table 3 6 Analyze menu items Menu Item Accelerator Description Display Fil ters This menu item brings up a dialog box that allows you to create and edit display filters You can name filters and you can save them for future use More detail on this subject is provided in Section 6 5 Defining and saving filters Apply as Filter Sie These menu items will change the current display filter and apply the changed filter immediately Depending on the chosen menu item the cur rent display filter string will be replaced or appended to by the selected protocol field in the packet details pane Prepare a Fil ter gt These menu items will change the current display filter but won t apply the changed filter Depending on the chosen menu item the current dis play filter string will be replaced or appended to by the selected protocol field in the packet de
92. d features of Ethereal will be described 122 Advanced Topics 7 2 Following TCP streams If you are working with TCP based protocols it can be very helpful to see the data from a TCP stream in the way that the application layer sees it Perhaps you are looking for passwords in a Tel net stream or you are trying to make sense of a data stream Maybe you just need a display filter to show only the packets of that TCP stream If so Ethereal s ability to follow a TCP stream will be useful to you Simply select a TCP packet in the packet list of the stream connection you are interested in and then select the Follow TCP Stream menu item from the Ethereal Tools menu or use the context menu in the packet list Ethereal will set an appropriate display filter and pop up a dialog box with all the data from the TCP stream laid out in order as shown in Figure 7 1 The Follow TCP Stream dia log box Note It is worthwhile noting that Follow TCP Stream installs a display filter to select all the packets in the TCP stream you have selected 7 2 1 The Follow TCP Stream dialog box Figure 7 1 The Follow TCP Stream dialog box Follow TCP stream Stream Content SUBSCRIBE UADPASRESIGE AREY es ROnA ARO HTTP 1 1 NT Upnp even allback Shes 192 168 0 2 5000 noti fy gt imeout Second 1800 User Agent mo Zulia 0 compatible UPnP 1 0 Windows NT 5 1 Host 192 168 0 ontent Length i Pragma no cache HTTP
93. e An example Let s assume that someone in Los Angeles captured a packet with Ethereal at exactly 2 o clock local time and sents you this capture file The capture file s time stamp will be represented in UTC as 10 o clock You are located in Berlin and will see 11 o clock on your Ethereal display Now you have a phone call video conference or internet meeting with that one to talk about that capture file As you are both looking at the displayed time on your local computers the one in Los Angeles still sees 2 o clock but you in Berlin will see 11 o clock The time displays are different as both Ethereal displays will show the different local times at the same point in time Conclusion You may not bother about the date time of the time stamp you currently look at unless you must make sure that the date time is as expected So if you get a capture file from a different time zone and or DST you ll have to find out the time zone DST difference between the two local times and mentally adjust the time stamps accordingly In any case make sure that every com puter in question has the correct time and time zone setting 129 Advanced Topics 7 5 Packet Reassembling 7 5 1 7 5 2 What is it Network protocols often need to transport large chunks of data which are complete in itself e g when transferring a file The underlying protocol might not be able to handle that chunk size e g limitation of the net
94. e each of its pages were shown as separ ate windows Even though the combined window is much more convenient to use these separate windows are still available The main reason is they might process faster for very large capture files However as the functionality is exactly the same as in the combined window they won t be discussed in detail here 143 Statistics 8 5 Conversations Statistics of the captured conversations 8 5 1 What is a Conversation A network conversation is the traffic between two specific endpoints For example an IP conversa tion is all the traffic between two IP addresses The description of the known endpoint types can be found in Section 8 4 1 What is an Endpoint 8 5 2 The Conversations window Beside the list content the conversations window work the same way as the endpoint ones see Sec tion 8 4 2 The Endpoints window for a description how it works Figure 8 4 The Conversations window Conversations test cap Ethernet 4 TCP 9 UDP 7 Ethernet Conversations Address A Address B Packets Bytes Packets A gt B Bytes A gt B Packets 4 lt B Bytes A lt B Netgear_2d 75 9a 192 168 0 2 114 12828 62 7313 52 5515 192 168 0 2 Broadcast 3 262 3 262 0 192 168 0 2 01 00 5e 00 00 16 2 108 2 108 0 192 168 0 2 01 00 5e 7f ff fa 1 Apply as Filter Selected lt gt B Prepare a Filter Not Selected gt B Find Packet and Selected lt B Colorize Conversa
95. e its power you have to start using it Figure 1 1 Ethereal captures packets and allows you to examine their content shows Ethereal having captured some packets and waiting for you to examine them Introduction 1 1 3 1 1 4 1 1 5 1 1 6 1 1 7 Figure 1 1 Ethereal captures packets and allows you to examine their content test cap Ethereal Dox File Edit Yiew Go Capture Analyze Statistics Help TAUA GB eS Rev vdF ERSA H eter 4 Expression Ysclear Y Apply No Time Source Destination Protocol Info 1 0 0000 0 IEG ARP who 2 I T 49 7 NENS s 4 0 726445 192 168 0 2 224 0 0 22 IGMP V3 Membership Report Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O00 0b S5d 20 cd 02 Ost Broadcast ff ff ff ff ff fh Address Resolution Protocol request gratuitous ARP oooo ff ff ff ff ff TF 00 Ob Sd 20 cd 02 08 06 OO 01 0010 08 OO 06 04 OO 01 00 Ob Sd 20 cd 02 cO ag 00 02 0020 00 00 00 00 00 00 cO ag O00 02 File Ds test cap 14 KB 00 00 02 P 120 D 120 M 0 Live capture from many different network media Despite its name Ethereal can capture traffic from network media other than Ethernet Which media types are supported depends on many things like the operating system you are using An overview of the supported media types can be found at http www ethereal com media html Import files from many other capture programs Etherea
96. e next file after the given number of byte s kilobyte s megabyte s gigabyte s have been captured Multiple files only Switch to the next file after the given number of second s minutes s hours s days s have elapsed Multiple files only Form a ring buffer of the capture files with the given number of files Multiple files only Stop capturing after switching to the next file the given number of times 4 5 3 Stop Capture frame after n packet s after n megabytes s Stop capturing after the given number of packets have been captured Stop capturing after the given number of byte s kilobyte s megabyte s gigabyte s have been cap tured This option is greyed out if Use multiple files is se lected 68 Capturing Live Network Data after n minute s Stop capturing after the given number of second s minutes s hours s days s have elapsed 4 5 4 Display Options frame 4 5 5 4 5 6 Update list This option allows you to specify that Ethereal should update the packet list pane in of packets real time If you do not specify this Ethereal does not display any packets until you in real stop the capture When you check this Ethereal captures in a separate process and time feeds the captures to the display process Automatic This option allows you to specify that Ethereal should scroll the packet list pane as scrolling in new packets come in so you are always looking at the last
97. e problem The standard problems are that you do not have GTK on your system or you do not have a recent enough version of GTK The configure will also fail if you do not have libpcap at least the re quired include files on your system Another common problem is for the final compile and link stage to terminate with a complaint of Output too long This is likely to be caused by an antiquated sed such as the one shipped with Sol aris Since sed is used by the libtool script to construct the final link command this leads to mys terious problems This can be resolved by downloading a recent version of sed from http direct ory fsf org GNU sed html If you cannot determine what the problems are send mail to the ethereal dev mailing list explain ing your problem and including the output from config log and anything else you think is rel evant like a trace of the make stage 22 Building and Installing Ethereal 2 Building from source under Windows It is recommended to use the binary installer for Windows until you want to start developing Ether eal on the Windows platform For further information how to build Ethereal for Windows from the sources have a look at the De velopment Wiki http wiki ethereal com Development for the latest available development docu mentation 23 Building and Installing Ethereal 2 8 Installing Ethereal under Windows In this section we explore installing Ethereal unde
98. e resolution Enable transport name resolution Tip gt You can set the following fields in this dialog box 4 5 1 Capture frame faults as this should work well in many cases If you are unsure which options to choose in this dialog box just try keeping the de Interface This field specifies the interface you want to capture on You can only capture on one interface and you can only capture 66 Capturing Live Network Data IP address Link layer header type Buffer size n megabyte s Capture packets in promiscuous mode Limit each packet to n bytes on interfaces that Ethereal has found on the system It is a drop down list so simply click on the button on the right hand side and select the interface you want It defaults to the first non loopback interface that supports capturing and if there are none the first loopback interface On some systems loopback interfaces cannot be used for capturing loopback interfaces are not available on Windows platforms This field performs the same function as the i lt interface gt command line option The IP address es of the selected interface If no address could be resolved from the system unknown will be shown Unless you are in the rare situation that you need this just keep the default For a detailed description see Section 4 7 Link layer header type Enter the buffer size to be used while capturing This is the size of the ke
99. e software we are referring to freedom not price Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software and charge for this service if you wish that you receive source code or can get it if you want it that you can change the software or use pieces of it in new free programs and that you know you can do these things To protect your rights we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights These restrictions translate to certain responsibilities for you if you distribute copies of the software or if you modify it For example if you distribute copies of such a program whether gratis or for a fee you must give the recipients all the rights that you have You must make sure that they too receive or can get the source code And you must show them these terms so they know their rights We protect your rights with two steps 1 copyright the software and 2 offer you this license which gives you legal permission to copy distribute and or modify the software Also for each author s protection and ours we want to make certain that everyone understands that there is no warranty for this free software If the software is modified by someone else and passed on we want its recipients to know that what they have is not the original so that any problems introduced by others will not reflect on the
100. eaders nettl Raw ICMPv6 with nettl headers GPRS LLC ml Juniper ATM1 m2 Juniper ATM2 Redback SmartEdge l Raw IP with nettl headers ther nett tr nettl i Ethernet with nettl headers fddi nettl unknown ne mtp2 with juniper pppoe Juniper PPPOE gcom tiel gcom seria x25 nettl default is Token Ring with nettl headers FDDI with nettl headers ttl Unknown link layer type with nettl headers phdr MTP2 with pseudoheader a GCOM TIE1 l GCOM Serial X25 with nettl headers the same as the input file v specifies verbose operation default is silent A range of records can be specified as well Where each option has the following meaning r This option specifies that the frames listed should be kept not deleted The default is to delete the listed frames 182 Related command line tools h This option provides help y This option specifies verbose operation The default is silent operation T encap type This option specifies the frame encapsulation type to use It is mainly for converting funny captures to something that Ethereal can deal with The default frame encapsulation type is the same as the input encapsulation F capture type This option specifies the capture file format to write the out put file in The default is libpcap format s snaplen Specifies that packets should be truncated to snaplen
101. eal is running Ethereal won t notice a change to the name resolution information once it s get cached If this information changes while Ethereal is running e g a new DHCP lease takes effect Ethereal won t notice it XXX is this true for all or only for DNS info Tip The name resolution in the packet list is done while the list is filled If a name could be resolved after a packet was added to the list that former entry won t be changed As the name resolution results are cached you can use View Reload to rebuild the pack et list this time with the correctly resolved names However this isn t possible while a capture is in progress Ethernet name resolution MAC layer Try to resolve an Ethernet MAC address e g 00 09 5b 01 02 03 to something more human read able ARP name resolution system service Ethereal will ask the operating system to convert an ether net address to the corresponding IP address e g 00 09 5b 01 02 03 gt 192 168 0 1 Ethernet codes ethers file If the ARP name resolution failed Ethereal tries to convert the ethernet address to a known device name which has been assigned by the user using an ethers file e g 00 09 5b 01 02 03 gt homerouter Ethernet manufacturer codes manuf file If both ARP and ethers didn t returned a result Ethere al tries to convert the first 3 bytes of an ethernet address to an abbreviated manufacturer name which has been assigned by the IEC e g 00 09 5b 01
102. ease see the tcpdump man page at http www tcpdump org tcp dump_man html for more details 74 Capturing Live Network Data 4 9 While a Capture is running While a capture is running the following dialog box is shown Figure 4 3 The Capture Info dialog box Ethereal Capture Interface Wev E Hf Captured Packets Total SCTP TCP UDF ICMP ARP OSPF GRE NetBIos IF VINES Other Running This dialog box will inform you about the number of captured packets and the time since the capture was started The selection which protocols are counted cannot be changed Tip This Capture Info dialog box can be hidden using the Hide capture info dialog op tion in the Capture Options dialog box 4 9 1 Stop the running capture A running capture session will be stopped in one of the following ways 1 Using the g Stop button from the Capture Info dialog box 75 Capturing Live Network Data 4 9 2 Note The Capture Info dialog box might be hidden if the option Hide capture info dialog is used 2 Using the menu item a Stop 3 Using the toolbar item Ql Stop 4 Pressing the accelerator keys Ctrl E 5 The capture will be automatically stopped if one of the Stop Conditions is exceeded e g the maximum amount of data was captured Restart a running capture A running capture session can be restarted with the same capture options than the last time this will rem
103. ece ence ence eeceeeceeeeaeeeueceueeau eens eeae esas 23 2 8 Installing Ethereal under Windows 0 cceceeeceeece ence ence ence ese eeeeeeaeeeaeeea seen sean eeaeegs 24 2 8 1 Instal Ethereal 3 c s ites each bh d ese tun AGT ath cae aS 24 2 32 Install Win PCap sss esssedocndbsens stan sot of ante oy Ae Gated EEEE a A ease hess Suse E Seansd we 25 2 3 3 Update Ethereal tyri secs cise secet utes dot E E vec Mal E EE E E medal eee 26 2 3 4 Update WinPCap x ssscessse sashes nea set bonhes se stag ssa ents eshte sat ber a e Tea reeds ease 26 2 8 5 Uninstall Ethereal csse ensien anser te cuca stat e aa teen outa ee cdests aeree ESE r 26 2 8 6 Uninstall WinPCap cersek cscs ug Soctae es vetoes cs cosa ees sebiaag dsddsacuastotacapsesnaess esbiesggeussee 27 3 User Interface lt 8 sec sects eeadeve EE a cae vain EEE EEE EEE EE EER S EEE ogy selec EEE 29 3 l Introduction sr r aaea a a a a a e O a a ee E 29 3 2 Start Ethereal seino oesi Eee EEEa E EEEE S EE A ESSEE E EEEE EEEN 30 3 3 The Main window as een e E E EE E EE R E E seal E 31 BAST eMC a a e a a e S deus a TEA E aaan 33 S52 Te EUS oa ENE S se E E S E tak OM Rie 34 3 0 The Edit MEDU seroren EENEN E E E e ES EEEE EES e 37 Ethereal User s Guide 3 7 The View MENU Ys salve shes eose reee ages Stated sh Seen Saves anes septa E O EPEE RESA NEEE hee SEERE ETAPAS 39 338 Ther Gor Men se ccees ASAE E ESE ESE cca Sodas ac eONd EEAS 43 3 9 The Capire menu 2 5 tuss S
104. ees Microseconds 0 123456 Expand all Nanoseconds 0 123456789 SYN Seq 0 Ack 0 Win v Collapse All rm gt E coloring Rules Bptured pd 20 cd 02 Dst Broadcast ff ff ff ff ff ff Show Packet in New Window bratuitous ARP ey Reload ctrl R 00 0 5d 20 cd 02 08 06 00 01 08 00 06 04 00 01 00 Ob Sd 20 cd 02 cO a8 00 02 00 00 00 00 00 00 cO a8 00 02 ftest cap 14 KB 00 00 02 P 120 D 120 M 0 Table 3 3 View menu items Menu Item Accelerator Description Main Toolbar This menu item hides or shows the main toolbar see Section 3 13 The Main toolbar Filter Toolbar This menu item hides or shows the filter toolbar see Section 3 14 The Filter toolbar Statusbar This menu item hides or shows the statusbar see Section 3 18 The Statusbar Packet List This menu item hides or shows the packet list pane see Section 3 15 The Packet List pane Packet Details This menu item hides or shows the packet details pane see Section 3 16 The Packet Details pane 39 User Interface Menu Item Accelerator Description Packet Bytes This menu item hides or shows the packet bytes pane see Section 3 17 The Packet Bytes pane Time Display Format gt Date and Time of Selecting this tells Ethereal to display the time stamps in date and time of day format see Section 6 9 Time display formats and time references
105. er to match the different policies for unix and windows platforms different folders for these files are used and Tip A list of the folders Ethereal actually uses can be found under the Folders tab in the dialog box coming up when you select About Ethereal from the Help menu Table A 1 Configuration files and folders overview File Folder Description Unix Linux Windows folders folders preferences Settings from the etc ethereal conf ETHEREAL ethereal conf Preferences dialog S HOME ethereal APPDATA Ethereal preferences box preferences recent Recent GUI set HOME ethereal APPDATA Ethereal recent tings e g recent recent files lists cfilters Capture filters HOME ethereal 7ETHEREAL cfilters cfilters APPDATA Ethereal cfilters dfilters Display filters HOME ethereal 7ETHEREAL dfilters dfilters APPDATA Ethereal dfilters colorfilters Coloring rules HOME ethereal 7ETHEREAL colorfilters colorfilters APPDATA Ethereal colorfilters dis Disabled proto HOMF ethereal 7ETHEREAL disabled_protos abled_protos cols disabled_protos APPDATA Ethereal disabled_protos ethers Ethernet name res etc ethers ETHEREAL ethers olution HOME ethereal APPDATA Ethereal ethers ethers manuf Ethernet name res etc manuf ETHEREAL manuf olution hosts IPv4 and IPv6 HOME ethereal APPDATA hosts name resolution hosts ipxnets IPX name resolu HOME ethe
106. ereal Display Filter tpkt_long tpkt_only ethernet broadcast ip broadcast deerpe DCERPC Fault Properties Filter name lip broadcast Filter string ip addr 255 255 255 255 113 Working with captured packets New Delete Filter Filter name Filter string Add Expression OK Apply Save Close This button adds a new filter to the list of filters The currently entered values from Filter name and Filter string will be used If any of these fields are empty it will be set to new This button deletes the selected filter It will be greyed out if no filter is selected You can select a filter from this list which will fill in the filter name and filter string in the fields down the bottom of the dialog box You can change the name of the currently selected filter here Note The filter name will only be used in this dialog to identify the filter for your convenience it will not be used else where You can add multiple filters with the same name but this is not very useful You can change the filter string of the currently selected filter here Dis play Filter only the string will be syntax checked while you are typing Display Filter only This button brings up the Add Expression dialog box which assists in building filter strings You can find more informa tion about the Add Expression dialog in Section 6 4 The Filter Ex pression d
107. ernel buffer This data is read by Ethereal and saved into the capture file s the user specified Different modes of operation are available when saving this packet data to the capture file s v J v Table 4 1 Capture file mode selected by capture options Tip Working with large files several 100 MB s can be quite slow If you plan to do a long term capture or capturing from a high traffic network think about using one of the Multiple files options This will spread the captured packets over several smaller files which can be much more pleasant to work with Note Using Multiple files may cut context related information Ethereal keeps context in formation of the loaded packet data so it can report context related problems like a stream error and keeps information about context related protocols e g where data is exchanged at the establishing phase and only referred to in later packets As it keeps this information only for the loaded file using one of the multiple file modes may cut these contexts If the establishing phase is saved in one file and the things you would like to see is in another you might not see some of the valuable context related inform ation Tip Information about the folders used for the capture file s can be found in Appendix A Configuration and other Files and Folders File option Use multiple Ring buffer Mode Resulting filename s used files o
108. es ponding Packet Go to the corresponding packet of the currently selected protocol field If the selected field doesn t correspond to a packet this item is greyed out First Packet Jump to the first packet of the capture file 43 User Interface Menu Item Accelerator Description Last Packet Jump to the last packet of the capture file 44 User Interface 3 9 The Capture menu The Ethereal Capture menu contains the fields shown in Table 3 5 Capture menu items Figure 3 7 The Capture Menu test cap Ethereal DES File Edit Yiew Go PeT Analyze Statistics Help amp Interfaces eal Sugai oS Sexe Raa Start DZ Eiter e oe aa 4 Expression Ys dear y apply p Restart Destination Protocol Info A Capture Filters Broadcast ARP who has 192 Gratuitous 4 0 726445 192 168 0 2 224 0 0 22 IGMP V3 Membership Report Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O00 0b S5d 20 cd 02 Ost Broadcast ff ff ff ff ff fh Address Resolution Protocol request gratuitous ARP oooo ff ff ff ff ff ff 00 Ob Sd 20 cd 02 08 06 OO 01 0010 08 OO 06 04 OO 01 00 Ob Sd 20 cd 02 c0 ag 00 02 0020 00 00 OO OO 00 OO cO as 00 02 File COs test cap 14 KB 00 00 02 P 120 D 120M 0 Table 3 5 Capture menu items Menu Item Accelerator Description Interfaces This menu item brings up a dialog box that shows
109. es of raw binary data to specified file Browse For other Folders e Name the filename to export the packet data to e The Save in folder field lets you select the folder to save to from some predefined folders e Browse for other folders provides a flexible way to choose a folder 93 File Input Output and Printing 5 7 Printing packets To print packets select the Print menu item from the File menu When you do this Ethereal pops up the Print dialog box as shown in Figure 5 10 The Print dialog box 5 7 1 The Print dialog box Figure 5 10 The Print dialog box Ethereal Print Printer Plain text PostScript Print command lpr rPacket Format Captured Displayed Packet summary line Packet Range All packets 768 Packet details Selected packet only 1 All collapsed s displayed All expanded Specify a packet range _ Packet bytes _ Each packet on a new page The following fields are available in the Print dialog box Printer This field contains a pair of mutually exclusive radio buttons e Plain Text specifies that the packet print should be in plain text e PostScript specifies that the packet print process should use PostScript to generate a better print output on PostScript aware printers e Output to file specifies that printing be done to a file which name is entered in the field or selected using t
110. ets in both input capture files to the output file The F flag can be used to specify the format in which to write the capture file it can write the file in libpcap format standard libpcap format a modified format used by some patched versions of libpcap the format used by Red Hat Linux 6 1 or the format used by SuSE Linux 6 3 snoop format uncompressed Sniffer format Microsoft Network Monitor 1 x format and the format used by Windows based versions of the Sniffer software Packets from the input files are merged in chronological order based on each frame s timestamp un less the a flag is specified Mergecap assumes that frames within a single capture file are already stored in chronological order When the a flag is specified packets are copied directly from each input file to the output file independent of each frame s timestamp If the s flag is used to specify a snapshot length frames in the input file with more captured data than the specified snapshot length will have only the amount of data specified by the snapshot length written to the output file This may be useful if the program that is to read the output file can not handle packets larger than a certain size for example the versions of snoop in Solaris 2 5 1 and Solaris 2 6 appear to reject Ethernet frames larger than the standard Ethernet MTU making them in capable of handling gigabit Ethernet captures if jumbo frames were used If the T flag is used to specify an e
111. ets on the network or do other active things except for name resolutions but even that can be disabled Introduction 1 2 Platforms Ethereal runs on 1 2 1 1 2 2 Ethereal currently runs on most UNIX platforms and various Windows platforms It requires GTK GLib libpcap and some other libraries in order to run If a binary package is not available for your platform you should download the source and try to build it Please report your experiences to ethereal dev AT ethereal com Binary packages are available for at least the following platforms Unix e Apple Mac OS X e BeOS e FreeBSD e HP UX e IBM AIx e NetBSD e OpenBSD e SCO UnixWare OpenUnix e SGI Irix e Sun Solaris Intel e Sun Solaris Sparc e Tru64 UNIX formerly Digital UNIX Linux e Debian GNU Linux e Gentoo Linux e IBM S 390 Linux Red Hat e Mandrake Linux e PLD Linux e Red Hat Linux e Rock Linux e Slackware Linux e Suse Linux Introduction 1 2 3 Microsoft Windows Maintained e Windows Server 2003 XP 2000 NT 4 0 e Windows Me 98 Unsupported Unmaintained because lack of required libraries e Windows CE e Windows NT XP Embedded e Windows 95 is no longer actively maintained by WinPcap but still may work perfectly No experiences fresh versions e Windows XP 64 bit Edition e Windows Vista aka Longhorn Please provide your experiences about these fresh versions to ethereal dev AT ethereal
112. f each packet To ensure that you capture complete packets use the following command tcpdump i lt interface gt s 1500 w lt some file gt You will have to specify the correct interface and the name of a file to save into In addition you will have to terminate the capture with C when you believe you have captured enough packets Note tcpdump is not part of the Ethereal distribution You can get it from ht tp www tcpdump org for various platforms 178 Related command line tools D 3 tethereal Terminal based Ethereal Tethereal is a terminal oriented version of ethereal designed for capturing and displaying packets when an interactive user interface isn t necessary or available It supports the same options as ether eal For more information on tethereal see the manual pages man tethereal 179 Related command line tools D 4 capinfos Print information about capture files Included with Ethereal is a small utility called capinfos which is a command line utility to print in formation about binary capture files Example D 1 Help information available from capinfos capinfos h Usage capinfos t c s d u a e y i z h lt capfile gt where t display the capture type of lt capfile gt c count the number of packets s display the size of the file d display the total length of all packets in the file in bytes u display the capture duration i
113. g at the last pack et If you do not specify this Ethereal simply adds new packets onto the end of the list but does not scroll the packet list pane Zoom In Ctrl Zoom into the packet data increase the font size Zoom Out Ctrl Zoom out of the packet data decrease the font size Normal Size Ctrl Set zoom level back to 100 set font size back to normal Resize All Columns Resize all column widths so the content will fit into it Note Resizing may take a significant amount of time especially if a large capture file is loaded Expand Sub trees This menu item expands the currently selected subtree in the packet de tails tree Expand All Ethereal keeps a list of all the protocol subtrees that are expanded and uses it to ensure that the correct subtrees are expanded when you display a packet This menu item expands all subtrees in all packets in the cap ture Collapse All This menu item collapses the tree view of all packets in the capture list Coloring Rules This menu item brings up a dialog box that allows you to color packets in the packet list pane according to filter expressions you choose It can be very useful for spotting certain types of packets see Section 9 3 Packet colorization Show Packet in New Window This menu item brings up the selected packet in a separate window The separate window shows only the tree view and byte view panes 41 User Interface
114. h is discussed further in Section 5 7 Printing packets Find Packet Edit Find Packet This item brings up a dialog box that allows you to find a packet There is further information on finding packets in Section 6 6 Finding packets Go Back Go Go Back This item jumps back in the packet history Go Forward Go Go Forward This item jumps forward in the packet history Go to Packet Go Go to Packet This item brings up a dialog box that allows you to specify a packet number to go to that packet Go To _ First Go First Packet Packet This item jumps to the first packet of the capture file Go To Last Pack Go Last Packet et This item jumps to the last packet of the capture file Colorize View Colorize Colorize the packet list or not Auto Scroll in Live Capture View Auto Scroll in Live Capture Auto scroll packet list while doing a live capture or not Zoom In View Zoom In Zoom into the packet data increase the font size Zoom Out View Zoom Out Zoom out of the packet data decrease the font size Normal Size View Normal Size Set zoom level back to 100 Resize Columns View Resize Columns Resize columns so the content fits into them Capture Filters Capture Capture Filters This item brings up a dialog box that allows you to create and edit capture filters You can name filters and you can save them for future use More detail on this subject is
115. hat Gilbert Ramirez saw its potential and contributed a low level dissector to it In October 1998 Guy Harris of Network Appliance was looking for something better than tcpview so he started applying patches and contributing dissectors to Ethereal In late 1998 Richard Sharpe who was giving TCP IP courses saw its potential on such courses and started looking at it to see if it supported the protocols he needed While it didn t at that point new protocols could be easily added So he started contributing dissectors and contributing patches The list of people who have contributed to Ethereal has become very long since then and almost all of them started with a protocol that they needed that Ethereal did not already handle So they copied an existing dissector and contributed the code back to the team Introduction 1 6 Development and maintenance of Ethereal Ethereal was initially developed by Gerald Combs Ongoing development and maintenance of Eth ereal is handled by the Ethereal team a loose group of individuals who fix bugs and provide new functionality There have also been a large number of people who have contributed protocol dissectors to Ethereal and it is expected that this will continue You can find a list of the people who have contributed code to Ethereal by checking the about dialog box of Ethereal or at the authors page on the Ethereal web site Ethereal is an open source software project and is released
116. he DNS server is unavailable this might take quite a while several seconds The ADNS service will work a bit differently It will also ask the DNS server but it won t wait for the answer It will just return to Ethereal in a very short amount of time The actual and the follow ing address fields won t show the resolved name until the ADNS call returned As mentioned above the values get cached so you can use View Reload to update these fields to show the re solved values hosts name resolution hosts file If DNS name resolution failed Ethereal will try to convert an IP address to the hostname associated with it using an hosts file provided by the user e g 65 208 228 223 gt www ethereal com IPX name resolution network layer ipxnet name resolution ipxnets file XXX add ipxnets name resolution explanation TCP UDP port name resolution transport layer Try to resolve a TCP UDP port e g 80 to something more human readable TCP UDP port conversion system service Ethereal will ask the operating system to convert a TCP or UDP port to its well known name e g 80 gt http XXX mention the role of the etc services file but don t forget the files and folders section 133 Advanced Topics 7 7 Checksums Several network protocols use checksums to ensure data integrity Tip Applying checksums as described here is also known as redundancy check What are checksums for Checksums are used
117. he browse button This field is where you enter the file to print to if you have selected Print to a file or you can click the button to browse the filesystem It is greyed out if Print to a file is not selected 94 File Input Output and Printing e Print command specifies that a command be used for printing Note These Print command fields are not available on windows platforms This field specifies the command to use for printing It is typically Ipr You would change it to specify a particular queue if you need to print to a queue other than the default An example might be lpr Pmypostscript This field is greyed out if Output to file is checked above Packet Range Select the packets to be printed see Section 5 8 The Packet Range frame Packet Format Select the output format of the packets to be printed You can choose how each packet is printed see Figure 5 12 The Packet Format frame 95 File Input Output and Printing 5 8 The Packet Range frame The packet range frame is a part of various output related dialog boxes It provides options to select which packets should be processed by the output function Figure 5 11 The Packet Range frame Captured Displayed All packets 120 O Selected packet only 1 Packet Range O Specify a packet range Lo o If the Captured button is set default all packets from the selected rule will be processed If the Displa
118. he command line eee eee cece eeceeceeceeeeeceereeeeeeeeeeeeseereeeereees 152 9 3 Packet COlOriZatiOMy sinies reos Ta E gute ee jena E E A EE E E e REES 157 94 Control Protocol GisseCtiOn srren rE oE E E a I E o a 160 9 4 1 The Enabled Protocols dialog bOX seesnesesseeesserrsrrsrreresrrrrsrrerreresrrsrereee 160 9 4 2 User Specified Decode yis c25 355 teeas vss otendses coboes ssbsaagssadeasuwesvtaadasessaess felieeapeats 162 9 4 3 Show User Specified Decodes 2 0 0 0 cee ee cece cece eeeceneceeeceeeeaeeeeeeeeeeaeeeaeeeaes 163 9S Preferences 2 onn EE ceed Gee cede as onde ha a swag veh snus cadens es Souba vides AE N A aTe 164 A Configuration and other Files and Folders ccceeccecceceneeecceeceeceeeeeeeeeseereseneresenereeaner 167 vi Ethereal User s Guide AT Windows folders 3 5 saci csiae dv voia aah O AE Aa AARE E nih dtean devs Seats ee EEA ags 170 As lid WandOws proles sneen cedacnadoued oa dauvenst eas lk asaibeatevareOl ca NE 170 A 1 2 Windows NT 2000 XP roaming profiles cece ee ceee eee ceecce teen eeeu seen sean eenee 171 A 1 3 Windows temporary folder cceceeeeeceeeeeceeececeeeceueeeeesceauereeueeeeaeseeuneeeegs 171 B Protocols and Protocol Fields cececceeeseceeceeceeceeeeeeeeeeeeeeeeeeeseeeeeeeeeseeresesereseereeener 173 Cy Ethereal Messages scot icchest sae tedene ses E A E e See ntien E R E dou e AEE N 174 Cul Packet List M ss ges
119. he place where things go wrong Please don t give something like I get a warning while doing x as this won t give a good idea where to look at Don t send large files Do not send large files gt 100KB to the mailing lists just place a note that further data is available on request Large files will only annoy a lot of people on the list who are not interested in your specific problem If required you will be asked for further data by the persons who really can help you A Don t send confidential information If you send captured data to the mailing lists be sure they don t contain any sensitive or confidential information like passwords or such 1 7 6 Reporting Crashes on UNIX Linux platforms When reporting crashes with Ethereal it is helpful if you supply the traceback information besides the information mentioned in Reporting Problems You can obtain this traceback information with the following commands gdb whereis ethereal cut f2 d cut d f2 core gt amp bt txt backtrace D Note Type the characters in the first line verbatim Those are back tics there Introduction Note backtrace is a gdb command You should enter it verbatim after the first line shown above but it will not be echoed The D Control D that is press the Control key and the D key together will cause gdb to exit This will leave you with a file called bt txt in the current directory Include the file with
120. ialog box Display Filter only This button applies the selected filter to the current display and closes the dialog Display Filter only This button applies the selected filter to the current display and keeps the dialog open Save the current settings in this dialog The file location and format is explained in Appendix A Configuration and other Files and Folders Close this dialog This will discard unsaved settings 114 Working with captured packets 6 6 Finding packets You can easily find packets once you have captured some packets or have read in a previously saved capture file Simply select the Find Packet menu item from the Edit menu Ethereal will pop up the dialog box shown in Figure 6 9 The Find Packet dialog box 6 6 1 The Find Packet dialog box Figure 6 9 The Find Packet dialog box Ethereal Find Packet Find By Display filter Hex value String You might first select the kind of thing to search for e Display filter Simply enter a display filter string into the Filter field select a direction and click on OK For example to find the three way handshake for a connection from host 192 168 0 1 use the following filter string ip addr 192 168 0 1 and tcp flags syn For more details on display filters see Section 6 2 Filtering packets while viewing e Hex Value Search for a specific byte sequence in the packet data For example use 00 00
121. iki Coloring Rules page at http wiki ethereal com ColoringRules To colorize packets select the Coloring Rules menu item from the View menu Ethereal will pop up the Coloring Rules dialog box as shown in Figure 9 1 The Coloring Rules dialog box Figure 9 1 The Coloring Rules dialog box Ethereal Coloring Rules fel Filter List is processed in order until match is found ot Move selected filter Manage smb nbss nbns nbipx ipxsap netbios up or down occ a uninterested ipx stp hsrp eigrp cdp m Import zs bi tc ul te il o 4 Bo oon E Once the Coloring Rules dialog box is up there are a number of buttons you can use depending on whether or not you have any color filters installed already Note You will need to carefully select the order the coloring rules are listed and thus ap plied as they are applied in order from top to bottom So more specific rules need to be listed before more general rules For example if you have a color rule for UDP be fore the one for DNS the color rule for DNS will never be applied as DNS uses UDP so the UDP rule will be matching first If this is the first time you have used Coloring Rules click on the New button which will bring up the Edit color filter dialog box as shown in Figure 9 2 The Edit Color Filter dialog box Figure 9 2 The Edit Color Filter dialog
122. ile As dialog box 0 cece cece cece cnee ce eeca een eeeaeeeaeeaeeeneeeas 82 5 3 2 Output File Formats ais eeraa E E EE E eects bane duis wee N iu ESE EEEN 84 5 4 Mereine Capture leS y e a A ANE e Tea E tive a E ESE 85 5 4 1 The Merge with Capture File dialog DOX ssssesseessesressesrsrerrsrrrrrerrerrsrrerreees 85 SS PIESEI na eo a A o AE N RE E E E EEA E gee E E ASEA EE o E 87 Jt The Teist Files sdialoe Dox ieai a E EE EE E EE TERNS 87 330 Exporting data simen e a a a Sous aot e Ould ae a a eae a NE 89 5 6 1 The Export as Plain Text File dialog bOX nseeseseesueeresuesrsrrerrsresrreresreererreees 89 5 6 2 The Export as PostScript File dialog Dox eee ce cece eeceeeee een eeneeeneeeneees 89 5 6 3 The Export as CSV Comma Seperated Values File dialog box 0 0 0 0 90 5 6 4 The Export as PSML File dialog DOX 0 0 eee ccee cece nee eeeece cena een iieri te 90 5 6 5 The Export as PDML File dialog box 20 0 0 cece cece cnec ee eece een eeen seca een ecueeees 91 5 6 6 The Export selected packet bytes dialog DOX 0 cee cee ceee eee c eee eeceeeeeneeeneeeneees 92 De fs PEIMUNE packets senera E ie A a ah vegues sues E EAE dteedwents 94 deel The Primnt dialog box 2c3scipeteei eh E bes cate ates Se RAL 94 5 9 The Racket Ran 86 framey oises lt ssavetenysuegesyy nea goa e shines e e pavuanasngesd des py E aS EEDE Ep 96 5 9 The Packet Format frame me Saves sinbeveedus E EEEE OEE Er EE
123. ill be greyed out if no packet was captured in the last second Packets s Number of packets captured in the last second Will be greyed out if no packet was captured in the last second Stop Stop a currently running capture Capture Start a capture on this interface immediately using the settings from the last cap ture Prepare Open the Capture Options dialog with this interface selected see Section 4 5 The Capture Options dialog box Close Close this dialog box 65 Capturing Live Network Data 4 5 The Capture Options dialog box When you select Start from the Capture menu or use the corresponding item in the Main tool bar Ethereal pops up the Capture Options dialog box as shown in Figure 4 2 The Capture Op tions dialog box Figure 4 2 The Capture Options dialog box Ethereal Capture Options Capture Interface Realtek RTL8139 810x Family Fast Ethernet NIC Device npr_ IP address 1 Buffer size p Capture packets in promiscuous mode C Limit each packet to bytes megabyte s eere Capture File s File C Use multiple files Stop Capture after E after C after Display Options Update list of packets in real time Automatic scrolling in live capture Hide capture info dialog Name Resolution Enable MAC name resolution Enable network nam
124. ill pop up the Preferences dialog box as shown in Figure 9 8 The prefer ences dialog box with the User Interface page as default On the left side is a tree where you can select the page to be shown Note Preference settings are added frequently For a recent explanation of the preference pages and their settings have a look at the Ethereal Wiki Preferences page at ht tp wiki ethereal com Preferences A Warning The OK or Apply button will not save the preference settings you ll have to save the settings by clicking the Save button e The OK button will apply the preferences settings and close the dialog e The Apply button will apply the preferences settings and keep the dialog open e The Save button will apply the preferences settings save the settings on the harddisk and keep the dialog open e The Cancel button will restore all preferences settings to the last saved state Figure 9 8 The preferences dialog box 164 Customizing Ethereal Ethereal Preferences E User Interface 165 Customizing Ethereal 166 Appendix A Configuration other Files and Folders Ethereal uses a number of files and folders while it is running Some of these reside in the personal configuration folder and are used to maintain information between runs of Ethereal while some of them are maintained in system areas The content format of the configuration files is the same on all platforms Howev
125. ing newer alpha or beta releases can be downloaded from the following locations e The main WinPcap site http www winpcap org e The ethereal com mirror http winpcap mirror ethereal com e The Wiretapped net mirror http www mirrors wiretapped net security packet capture winpcap At the download page you will find a single installer exe called something like auto installer which can be installed under various Windows systems including 9x Me NT4 0 2000 XP Update Ethereal From time to time you may want to update your installed Ethereal to a more recent version If you join Ethereal s announce mailing list you will be informed about new Ethereal versions see Sec tion 1 7 4 Mailing Lists for details how to subscribe to this list New versions of Ethereal usually become available every 4 8 weeks Updating Ethereal is done the same way as installing it you simply download and start the installer exe A reboot is usually not re quired and all your personal settings remain unchanged Update WinPcap New versions of WinPcap are less frequently available maybe only once in a year You will find WinPcap update instructions where you can download new WinPcap versions Usually you have to reboot the machine after installing a new WinPcap version A Warning If you have an older version of WinPcap installed you must un install it before in stalling the current version Recent versions of the WinPcap installer will take c
126. ion number of this License you may choose any version ever published by the Free Software Foundation 10 If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different write to the author to ask for permission For software which is copyrighted by the Free Software Foundation write to the Free Software Foundation we sometimes make exceptions for this Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally NO WARRANTY 11 BECAUSE THE PROGRAM IS LICENSED FR Ct E OF CHARGE THERE IS NO WARRANTY t 197 This Document s License GPL R TH HERW U ROGRAM TO THE EXTENT PERMITTED BY APPLICABLE LAW EXCEPT W STATED IN WRITING THE COPYRIGHT HOLDERS AND OR OTHER PARTIE OVID HE PROGRAM AS IS WITHOUT WARRANTY OF ANY KIND EI EXPR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRA S OF RCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE THE E E RISK AS THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU LD THE OGRAM PROVE DEFECTIVE YOU ASSUME THE COST OF ALL NECESSARY SERVICING PAIR OR CORRECTION EN S mti H El Ei H E H S SSED N CI
127. k layer header type In the usual case you won t have to choose this link layer header type The following paragraphs describe the exceptional cases where selecting this type is possible so you will have a guide what to do If you are capturing on an 802 11 device on some versions of BSD this might offer a choice of Eth ernet or 802 11 Ethernet will cause the captured packets to have fake Ethernet headers 802 11 will cause them to have IEEE 802 11 headers Unless the capture needs to be read by an application that doesn t support 802 11 headers you should select 802 11 If you are capturing on an Endace DAG card connected to a synchronous serial line this might offer a choice of PPP over serial or Cisco HDLC if the protocol on the serial line is PPP select PPP over serial and if the protocol on the serial line is Cisco HDLC select Cisco HDLC If you are capturing on an Endace DAG card connected to an ATM network this might offer a choice of RFC 1483 IP over ATM or Sun raw ATM If the only traffic being captured is RFC 1483 LLC encapsulated IP or if the capture needs to be read by an application that doesn t support SunATM headers select RFC 1483 IP over ATM otherwise select Sun raw ATM If you are capturing on an Ethernet device this might offer a choice of Ethernet or DOCSIS If you are capturing traffic from a Cisco Cable Modem Termination System that is putting DOCSIS traffic onto the Ethernet to be
128. ked packets only gt Specify a packet range File type libpcap tcpdump Ethereal etc w Browse For other Folders With this dialog box you can perform the following actions 1 Type in the name of the file you wish to save the captured packets in as a standard file name in your file system 2 Select the directory to save the file into 3 Select the range of the packets to be saved see Section 5 8 The Packet Range frame 4 Specify the format of the saved capture file by clicking on the File type drop down box You can choose from the types described in Section 5 3 2 Output File Formats Note Some capture formats may not be available depending on the packet types cap tured Tip 7 You can convert capture files from one format to another by reading in a capture 83 File Input Output and Printing file and writing it out using a different format 5 Use Browse for other folders to browse files and folders in your file system 6 Click on the Save button to accept your selected file and save to it If Ethereal has a problem saving the captured packets to the file you specified it will display an error dialog box After clicking OK on this error dialog box you can try again 7 Click on the Cancel button to go back to Ethereal and not save the captured packets 5 3 2 Output File Formats The following file formats can be saved by Ethereal so other capture tools can read
129. kets containing a comma separated list of range specifiers eth src 0 3 00 00 83 The example above uses the n m format to specify a single range In this case n is the beginning offset and m is the length of the range being specified eth src 1 2 00 83 The example above uses the n m format to specify a single range In this case n is the beginning offset and m is the ending offset eth src 4 00 00 83 00 The example above uses the m format which takes everything from the beginning of a sequence to offset m It is equivalent to 0 m eth src 4 20 20 The example above uses the n format which takes everything from offset n to the end of the sequence 109 Working with captured packets English C like Description and example eth src 2 83 The example above uses the n format to specify a single range In this case the ele ment in the sequence at offset n is selected This is equivalent to n 1 eth src 0 3 1 2 4 4 2 00 00 83 00 83 00 00 83 00 20 20 83 Ethereal allows you to string together single ranges in a comma separated list to form compound ranges as shown above 6 3 4 A common mistake A Warning Using the operator on combined expressions like eth addr ip addr tcp port udp port and alike will probably not work as expected Often people use a filter string to display something like ip addr 1 2 3 4 which will display all packets containing the IP
130. l can open packets captured from a large number of other capture programs For a list of in put formats see Section 5 2 2 Input File Formats Export files for many other capture programs Ethereal can save packets captured in a large number of formats of other capture programs For a list of output formats see Section 5 3 2 Output File Formats Many protocol decoders There are protocol decoders or dissectors as they are known in Ethereal for a great many proto cols see Appendix B Protocols and Protocol Fields Open Source Software Ethereal is an open source software project and is released under the GNU General Public Licence GPL You can freely use Ethereal on any number of computers you like without worrying about 2 Introduction license keys or fees or such In addition all source code is freely available under the GPL Because of that it is very easy for people to add new protocols to Ethereal either as plugins or built into the source and they often do 1 1 8 What Ethereal is not Here are some things Ethereal does not provide e Ethereal isn t an intrusion detection system It will not warn you when someone does strange things on your network that he she isn t allowed to do However if strange things happen Ether eal might help you figure out what is really going on e Ethereal will not manipulate things on the network it will only measure things from it Ethere al doesn t send pack
131. lder in your profile data typically something like C Documents and Settings lt username gt Local Settings will not be trans ferred to the domain server This is the default for temporary capture files Windows temporary folder Ethereal uses the folder which is set by the TMPDIR or TEMP environment variable This variable will be set by the windows installer The default location for temporary files on NT 4 is just C TEMP and in 2000 the default location is some directory under your profile directory but it might have Temporary Files in the path name 171 Configuration and other Files and Folders 172 Appendix B Protocols and Protocol Fields Ethereal distinguishes between protocols e g tcp and protocol fields e g tcp port A comprehensive list of all protocols and protocol fields can be found at ht tp www ethereal com docs dfref 173 Appendix C Ethereal Messages Ethereal provides you with additional information generated out of the plain packet data or it may need to indicate dissection problems Messages generated by Ethereal are usually placed in paren theses C 1 Packet List Messages These messages might appear in the packet list C 1 1 Malformed Packet Malformed packet means that the protocol dissector can t work out the contents of the packet any further This can have various reasons e Wrong dissector Ethereal errorneously has chosen the wrong protocol di
132. ll also indicate the type of value for the field name you have selected like character string Some of the protocol fields have predefined values available much like enum s in C If the selected protocol field has such values defined you can choose one of them here XXX add an explanation here When you have built a satisfactory expression click OK and a filter string will be built for you You can leave the Add Expression dialog box without any effect by clicking the Cancel 112 Working with captured packets 6 5 Defining and saving filters You can define filters with Ethereal and give them labels for later use This can save time in remem bering and retyping some of the more complex filters you use To define a new filter or edit an existing one select the Capture Filters menu item from the Cap ture menu or the Display Filters menu item from the Analyze menu Ethereal will then pop up the Filters dialog as shown in Figure 6 8 The Capture Filters and Display Filters dialog boxes Note The mechanisms for defining and saving capture filters and display filters are almost identical So both will be described here differences between these two will be marked as such A Warning You must use Save to save your filters permanently Ok or Apply will not save the fil ters so they will be lost when you close Ethereal Figure 6 8 The Capture Filters and Display Filters dialog boxes Eth
133. ll packets These mark function are available from the Edit menu and the Mark packet toggle function is also available from the pop up menu of the Packet List pane 118 Working with captured packets 6 9 Time display formats and time references 6 9 1 While packets are captured each packet is timestamped These timestamps will be saved to the cap ture file so they will be available for later analysis A detailed description of timestamps timezones and alike can be found at Section 7 3 Time The timestamp presentation format and the precision in the packet list can be chosen using the View menu see Figure 3 5 The View Meng The available presentation formats are e Date and Time of Day 1970 01 01 01 02 03 123456 The absolute date and time of the day when the packet was captured Time of Day 01 02 03 123456 The absolute time of the day when the packet was captured e Seconds Since Beginning of Capture 123 123456 The time relative to the start of the capture file or the first Time Reference before this packet see Section 6 9 1 Packet time referen cing e Seconds Since Previous Packet 1 123456 The time relative to the previous packet The available precisions aka the number of displayed decimal places are e Automatic The timestamp precision of the loaded capture file format will be used the default e Seconds Deciseconds Centiseconds Milliseconds Microseconds or
134. ly the packets that pass this filter will be taken into account for that graph e Style the style of the graph Line Impulse FBar e X Axis e Tick interval an interval in x direction lasts 10 1 0 1 0 01 0 001 seconds e Pixels per tick use 10 5 2 1 pixels per tick interval e Y Axis 145 Statistics e Unit the unit for the y direction Packets Tick Bytes Tick Advanced e Scale the scale for the y unit 10 20 50 100 200 500 XXX describe the Advanced feature 146 Statistics 8 7 Service Response Time The service response time is the time between a request and the corresponding response This in formation is available for many protocols Service response time statistics are currently available for the following protocols e DCE RPC e Fibre Channel e H 225 RAS e LDAP e MGCP e ONC RPC e SMB As an example the DCE RPC service response time is described in more detail Note The other Service Response Time windows will work the same way or only slightly different compared to the following description 8 7 1 The Service Response Time DCE RPC window The service response time of DCE RPC is the time between the request and the corresponding re sponse First of all you have to select the DCE RPC interface Figure 8 6 The Compute DCE RPC statistics window Ethereal Compute DCE RPC SRT statistics Sele Program fnone EPM w Version Beej ooo You can optionally
135. mputer the time is essentially the same as before you are simply in a different time zone with a different local time Tip Ne You can use the Network Time Protocol NTP to automatically adjust your computer to the correct time by synchronizing it to internet NTP clock servers NTP clients are available for all operating systems that Ethereal supports and for a lot more for ex amples see http www ntp org Ethereal and Time Zones So what s the relationship between Ethereal and time zones anyway Ethereal s native capture file format libpcap format and some other capture file formats such as the Windows Sniffer EtherPeek AiroPeek and Sun snoop formats save the arrival time of packets as UTC values UN X systems and Windows NT based systems Windows NT 4 0 Windows 2000 Windows XP Windows Server 2003 Windows Vista represent time internally as UTC When Ethereal is capturing no conversion is necessary However if the system time zone is not set correctly the system s UTC time might not be correctly set even if the system clock appears to dis play correct local time Windows 9x based systems Windows 95 Windows 98 Windows Me represent time internally as local time When capturing WinPcap has to convert the time to UTC be fore supplying it to Ethereal If the system s time zone is not set correctly that conversion will not be done correctly Other capture file formats such as the Microsoft Network Monitor DOS
136. n seconds a display the capture start time e display the capture end time y display average data rate in bytes i display average data rate in bits z display average packet size in bytes h produces this help listing If no data flags are given default is to display all statistics 180 Related command line tools D 5 editcap Edit capture files Included with Ethereal is a small utility called editcap which is a command line utility for working with capture files Its main function is to remove packets from capture files but it can also be used to convert capture files from one format to another as well as print information about capture files Example D 2 Help information available from editcap editcap exe h Usage editcap r h v T lt encap type gt E lt probability gt F lt capture type gt gt s lt snaplen gt t lt time adjustment gt lt infile gt lt outfile gt lt record gt lt record gt where u lza lt probability gt specifies the probability between 0 and 1 that a particular byte will will have an error lt capture type gt specifies the capture file type to write libpcap libpcap tcpdump Ethereal etc rh6_llibpcap RedHat Linux 6 1 libpcap tcpdump suse6_3libpcap SuSE Linux 6 3 libpcap tcpdump modlibpcap modified libpcap tcpdump nokialibpcap Nokia libpcap tcpdump lanalyzer Novell LANalyzer ngsniffer Network Asso
137. n your self What are time zones People expect that the time reflects the sunset Dawn should be in the morning maybe around 06 00 and dusk in the evening maybe at 20 00 These times will obviously vary depending on the season It would be very confusing if everyone on earth would use the same global time as this would correspond to the sunset only at a small part of the world For that reason the earth is split into several different time zones each zone with a local time that corres ponds to the local sunset The time zone s base time is UTC Coordinated Universal Time or Zulu Time military and aviation The older term GMT Greenwich Mean Time shouldn t be used as it is slightly incorrect up to 0 9 seconds difference to UTC The UTC base time equals to 0 based at Greenwich England and all time zones have an offset to UTC between 12 to 14 hours For example If you live in Berlin you are in a time zone one hour earlier than UTC so you are in time zone 1 time difference in hours compared to UTC If it s 3 o clock in Berlin it s 2 o clock in UTC at the same moment Be aware that at a few places on earth don t use time zones with even hour offsets e g New Delhi uses UTC 05 30 Further information can be found at http en wikipedia org wiki Time zone and ht tp en wikipedia org wiki Coordinated_Universal_Time What is daylight saving time DST Daylight Saving Time DST also known as Summer Time is in
138. ncapsulation type the encapsulation type of the output capture file will be forced to the specified type rather than being the type appropriate to the encapsulation type of the input capture file Note that this merely forces the encapsulation type of the output file to be the specified type the packet headers of the packets will not be translated from the encapsulation type of the input capture file to the specified encapsulation type for example it will not translate an Ethernet capture to an FDDI capture if an Ethernet capture is read and T fddi is specified Example D 3 Help information available from mergecap mergecap ex h mergecap version 0 10 5 Usage mergecap hva s lt snaplen gt T lt encap type gt F lt capture type gt w lt outfile gt lt infile gt where h produces this help listing v verbose operation default is silent a files should be concatenated not merged Default merges based on frame timestamps s lt snaplen gt truncate packets to lt snaplen gt bytes of data w lt outfile gt sets output filename to lt outfile gt T lt encap type gt encapsulation type to use ther Ethernet tr Token Ring slip SLIP ppp PPP fddi FDDI fddi swapped FDDI with bit swapped MAC addresses 184 Related command line tools rawip Raw I arcnet ARCNET arcnet_linux Linux ARCNET atm rfc1483 RFC 1483 ATM linux atm clip Linux ATM CLIP lapb LAPB
139. nd Installing Ethereal 2 4 Building Ethereal from source under UNIX Use the following general steps if you are building Ethereal from source under a UNIX operating system 1 Unpack the source from its gzip d tar file If you are using Linux or your version of UNIX uses GNU tar you can use the following command tar zxvf ethereal 0 10 14 tar gz For other versions of UNIX You will want to use the following commands gzip d ethereal 0 10 14 tar gz tar xvf ethereal 0 10 14 tar Note Note 4 The pipeline gzip dc ethereal 0 10 14 tar gz tar xvf will work here as well If you have downloaded the Ethereal tarball under Windows you may find that your browser has created a file with underscores rather than periods in its file name 2 Change directory to the Ethereal source directory 3 Configure your source so it will build correctly for your version of UNIX You can do this with the following command configure If this step fails you will have to rectify the problems and rerun configure Troubleshooting hints are provided in Section 2 6 Troubleshooting during the install on Unix 4 Build the sources into a binary with the make command For example make 5 Install the software in its final destination using the command make install Building and Installing Ethereal Once you have installed Ethereal with make install above you should be able to run it by entering ethereal
140. nk Network Transport TCP source 3196 port s as 4JP13 Do not decode 4 4000 BEEP Show Current CAST The content of this dialog box depends on the selected packet when it was opened A Warning The user specified decodes can not be saved If you quit Ethereal these settings will be lost 1 Decode Decode packets the selected way 2 Do not decode Do not decode packets the selected way 3 Link Network Transport Specify the network layer at which Decode As should take place Which of these pages are available depends on the content of the selected packet when this 162 Customizing Ethereal dialog box was opened 4 Show Current Open a dialog box showing the current list of user specified decodes 5 OK Apply the currently selected decode and close the dialog box 6 Apply Apply the currently selected decode and keep the dialog box open 7 Cancel Cancel the changes and close the dialog box 9 4 3 Show User Specified Decodes This dialog box shows the currently active user specified decodes Figure 9 7 The Decode As Show dialog box Ethereal Deco E led Table Port Initial Current TCP pork 139 MESS CAST 1 OK Close this dialog box 2 Clear Removes all user specified decodes 163 Customizing Ethereal 9 5 Preferences There are a number of preferences you can set Simply select the Preferences menu item from the Edit menu and Ethereal w
141. nodes Show the wiki page corresponding to the currently selected protocol in your web browser Show the filter field reference web page corresponding to the currently selected protocol in your web browser The menu item takes you to the properties dialog and selects the page corresponding to the protocol if there are properties associated with the highlighted field More information on preferences can be found in Figure 9 8 The preferences dia log box This menu item is the same as the Analyze menu item of the same name This menu item causes name resolution to be performed for the selected packet but NOT every packet in the capture If the selected field has a corresponding packet go to it Cor responding packets will usually be a request response packet pair or such Figure 6 5 Pop up menu of Packet Bytes pane 103 Working with captured packets File Edit Yiew Go Capture Analyze Statistics Help BwHa ae ocM x eS P evxvv Fzt EF agqg citer dP Expression Year Y Apply No Time Source Destination Protocol Info gt Seg 1 Ack 1 Wi f Frame 23 60 bytes on wire 60 bytes captured B Ethernet II Src Netgear_2d 75 9a O0 09 Sbi2d 75 9a Ost 192 168 0 2 O0 0b S5d 20 cd 02 Destination 192 168 0 2 00 0b 5d 20 cd 02 Source Netgear_2d 75 9a O00 09 Sb 2d 75 9a Type IP Ox 0 Trailer 000000000000 Internet Protocol Src 192 168 0 1 192 168 0 1 Ost
142. not covered by this License they ar running the Program is not restricted is covered only if its conte outside its scope T and the output f nts constitute a work based on the Program independent of having been made by running the Whether that is true depends 1 You may copy a source code as you receive it in any medium conspicuously and appropriately publish on each copy an copyright notice and disclaimer of warranty notices that refer on what the Program does nd distribute verbatim copies of the provided keep intac to this License and to the absence o and give any other recipients of the Program a copy of along with the Program You may charge a fee for the physical act of transferri you may at your option offer warranty protection in exc 2 You may modify your copy or copies of of it thus forming a work based on the Program and co the terms o distribute su a You mu b You mu whole or ch modifications or work under above provided that you also meet all of t st st cause the modified files to stating that you changed the files and cause any work that part thereof to be licensed a nd r the terms of thi parties u hen run otice th warrant hese con icense oes not TtTAawrtoasor Za hese requir If the modi Y at y di no dentifiable hemselves t m se nd can be reaso ections when
143. nse Of course the commands you use may be called something other than show w and show c they could even be mouse clicks or menu items whatever suits your program You should also get your employer if you work as a programmer or your school if any to sign a copyright disclaimer for the program if necessary Here is a sample alter the names 198 This Document s License GPL Yoyodyne Inc hereby disclaims all copyright interest in the program Gnomovision which makes passes at compilers written by James Hacker lt signature of Ty Coon gt 1 April 1989 Ty Coon President of Vice This General Public License does not permit incorporating your program into proprietary programs If your program is a subroutine library you may consider it more useful to permit linking proprietary applications with the library If this is what you want to do use the GNU Library General Public License instead of this License 199
144. nu item allows you to export all or some of the packets in the capture file to a plain ASCII text file It pops up the Ethereal Export dia log box which is discussed further in Section 5 6 1 The Export as Plain Text File dialog box This menu item allows you to export the or some of the packets in the capture file to a PostScript file It pops up the Ethereal Export dialog box which is discussed further in Section 5 6 2 The Export as PostScript File dialog box Export gt as CcSyv Comma Sep arated Values packet sum mary file This menu item allows you to export the or some of the packet summar ies in the capture file to a csv file e g used by spreadsheet programs It pops up the Ethereal Export dialog box which is discussed further in Section 5 6 3 The Export as CSV Comma Seperated Values File dialog box Export gt as PSML file This menu item allows you to export the or some of the packets in the capture file to a PSML packet summary markup language XML file It pops up the Ethereal Export dialog box which is discussed further in Section 5 6 4 The Export as PSML File dialog box 35 User Interface Menu Item Accelerator Description Export gt as PDML file This menu item allows you to export the or some of the packets in the capture file to a PDML packet details markup language XML file It
145. ny quotes even if the path contains spaces Example thereal setup 0 10 13 exe NCRC S desktopicon yes quicklaunchicon no D C 2 8 1 2 Components Beside the usual installer options like where to install the program there are several optional com ponents Tip If you are unsure which settings to select just keep the default settings 24 Building and Installing Ethereal 2 8 2 The Components both Ethereal GTK1 and 2 cannot be installed at the same time Etheral GTK1 Ethereal is a GUI network protocol analyzer Etheral GTK2 Ethereal is a GUI network protocol analyzer using the modern GTK2 GUI toolkit recommended GTK Wimp GTKWimp is the GTK2 windows impersonator native Win32 look and feel re commended Tethereal Tethereal is a command line based network protocol analyzer The dissection extensions for Ethereal and Tethereal Dissector Plugins Plugins with some extended dissections Tree Statistics Plugins Plugins with some extended statistics Mate Meta Analysis and Tracing Engine user configurable extension s of the display filter engine see http wiki ethereal com Mate for details SNMP MIBs SNMP MIBs for a more detailed SNMP dissection The Tools Editcap Editcap is a program that reads a capture file and writes some or all of the packets into another capture file Text2Pcap Text2pcap is a program that reads in an ASCII hex dump and writes the data into
146. o display that packet data as detailed as possible You could think of a network packet analyzer as a measuring device used to examine what s going on inside a network cable just like a voltmeter is used by an electrician to examine what s going on inside an electric cable but at a higher level of course In the past such tools were either very expensive proprietary or both However with the advent of Ethereal all that has changed Ethereal is perhaps one of the best open source packet analyzers available today Some intended purposes Here are some examples people use Ethereal for e network administrators use it to troubleshoot network problems e network security engineers use it to examine security problems e developers use it to debug protocol implementations e people use it to learn network protocol internals Beside these examples Ethereal can be helpful in many other situations too Features The following are some of the many features Ethereal provides e Available for UNIX and Windows e Capture live packet data from a network interface e Display packets with very detailed protocol information e Open and Save packet data captured e Import and Export packet data from and to a lot of other capture programs e Filter packets on many criteria e Search for packets on many criteria e Colorize packet display based on filters e Create various statistics e and a lot more However to really appreciat
147. o initiate the filter Figure 6 6 Filtering on the TCP protocol shows an example of what happens when you type tep in the filter field Note All protocol and field names are entered in lowercase Also don t forget to press enter after entering the filter expression Figure 6 6 Filtering on the TCP protocol 105 Working with captured packets test cap Ethereal File Edit Yiew Go Capture Analyze Statistics Help TANA SCAxe S Ber OFZ ETaQ Eiter ficp 4b Expression Year Y Apply No Time Source Destination Protocol Info 23 0 001026 92 0 92 0 2 GP 1025 gt 5000 ACK Seg 1 _Ack 1 Wi lt Frame 23 60 bytes on wire 60 bytes captured Ethernet II Src Netgear_2d 75 9a O0 09 Sbi2d 75 9a Dst 192 168 0 2 O0 0b 5d 20 cd 02 Internet Protocol Src 192 168 0 1 192 168 0 1 Ost 192 168 0 2 192 168 0 2 Transmission Control Protocol Src Port 1025 1025 Dst Port 5000 C 9a 08 00 45 00 ag 00 01 cO ag 88 00 00 67 81 3c 37 7f a7 50 10 ransmission Control Protocol tcp 20 bytes P 120 D 103 M 0 As you might have noticed only packets of the TCP protocol are displayed now e g packets 1 10 are hidden The packet numbering will remain as before so the first packet shown is now packet number 11 Note When using a display filter all packets remain in the capture file The display filter only changes the display of the capture file but not its conten
148. on of the whole must be on the terms of ply to those ut when you hose permissions for other licensees ext nd thus to each and every part regardless of who wrote it nd to the 195 This Document s License GPL nt of this section to cla ten entirely by you ntrol the distribution of n the Program Thus it is not the inte your rights to work writ exercise the right to co collective works based o In addition mere aggregation of another work not with the Program or with a work based on the Pro a storage or distribution medium does not bring t the scope of this License 3 You may copy and distribute the Program or under Section 2 in object code or executable for Sections 1 and 2 above provided that you also do t wit hich a Accompany i source code w h the complete correspondi must be distributed under rather im rights or contest the intent is to derivative or based on the Program gram on a volume of he other work under a work based on it m under the terms of one of the following ng machine readable the terms of Sections 1 and 2 above on a medium customarily used fo b Accompany it with a written offer valid f years to give any third party for a charge cost of physically performing source distribu machine readable copy of the corresponding so distributed under th customarily used for software interchange or ect spo c Accompany it wit to distribute cor
149. otocol Andrew File System 4FS Authentication Header AOL Instant Messenger AIM Administrative AIM Advertisements AIM Privacy Management Service AIM Buddylist Service AIM Chat Service AIM Chat Navigation AIM Directory Search v gt Disabling a protocol prevents higher layer protocols from being displayed Enable All Disable All To disable or enable a protocol simply click on it using the mouse or press the space bar when the protocol is highlighted Warning You have to use the Save button to save your settings The OK or Apply buttons will not save your changes permanently so they will be lost when Ethereal is closed You can choose from the following actions 1 Enable All Enable all protocols in the list 2 Disable All Disable all protocols in the list 3 Invert Toggle the state of all protocols in the list 4 OK Apply the changes and close the dialog box 161 Customizing Ethereal 5 Apply Apply the changes and keep the dialog box open 6 Save Save the settings to the disabled_protos see Appendix A Configuration and other Files and Folders for details 7 Cancel Cancel the changes and close the dialog box 9 4 2 User Specified Decodes The Decode As functionality let you temporarily divert specific protocol dissections This might be useful for example if you do some uncommon experiments on your network Figure 9 6 The Decode As dialog box Ethereal Decode As Li
150. ou display a packet This menu item collapses the tree view of all packets in the capture list Apply as Filter X X Analyze Prepare a Filter X X Analyze Follow TCP X X j Analyze stream View all the data on a TCP stream between a pair of nodes Wiki Protocol X Page Show the wiki page corresponding to the currently se lected protocol in your web browser x lt Filter Field Ref erence Show the filter field reference web page corresponding to the currently selected protocol in your web browser gt x lt Protocol Prefer ences The menu item takes you to the preferences dialog and selects the page corresponding to the protocol if there are settings associated with the highlighted field More information on preferences can be found in Section 9 5 100 Working with captured packets Item Lis De Byt Menu Description t Jtail jes s Preferences Decode As X X Analyze Print X j File Print the selected packet s Show Packet in X View New Window Display the selected packet in another window Resolve name X J View Name Res olution Cause a name resolution to be performed for the selec ted packet but NOT for every packet in the capture x lt Go to Corres Go ponding Packet If the selected field has a packet number in it go to it The corresponding packet will often be a response which is reques
151. ove all packets previously captured This can be useful if some uninteresting packets are cap tured and there s no need to keep them Restart is a convenience function and equivalent to a capture stop following by an immediate cap ture start A restart can be triggered in one of the following ways 1 Using the menu item Capture F ifg Restart 2 Using the toolbar item 76 Capturing Live Network Data 77 Chapter 5 File Input Output and Printing 5 1 Introduction This chapter will describe input and output of capture data Open Import capture files in various capture file formats Save Export capture files in various capture file formats Merge capture files together Print packets 78 File Input Output and Printing 5 2 Open capture files 5 2 1 Ethereal can read in previously saved capture files To read them simply select the menu or toolbar item File r Open Ethereal will then pop up the File Open dialog box which is discussed in more detail in Section 5 2 1 The Open Capture File dialog box Note You can also use drag and drop to open a file by simply dropping the desired file from your file manager onto Ethereal s main window However drag and drop is not available won t work in all desktop environments If you didn t save the current capture file before you will be asked to do so to prevent data loss this behaviour can be disabled in the preferen
152. oya Se i RU sae eS cate a ae ERS 45 3 10 The Analyze Menu sc ccesacesoces a e a E oy teaaes tessa soap psuee E T Set tes dover eee bean set 47 Sul dhe Statistics ment ot jyvehethe swe st p e EE vtectny orca ste ER yt r O wb seagate 49 3 12 The Help Menu nesia nane dens e a a R cubed dau a saben goes coun laa dase EA 51 3 13 he Main toolbar arne o ea E R E ae Eee eo 53 3 14 The Filter toolbar eirese aneren ess ota nis eebag sen toca ag ssc man sasyoteads OOI ERE PIEEO RA 56 3 15 The Packet List pane vice ccs 0i3 urr e oen piensa E e EEE S EEEE EOE EEES 37 3 16 The Packet Details pane sscscss shchstesdeoes athoot ceased e sasboriisss aaesiee picsades sate 58 3 17 The Packet Bytes pane 3sisceccons ies reep tenes csecde ig EEVEE EE OEE EESE ES EEEE a 59 3 18 The Statusbar ovotes ge ocd causes vote toss etebasedy EPEa E E RSE KIERRE vite a ds seasaeaee PEES VENS 60 4 Capturing Live Network Data sroine ponen Err ca EES EEE EEK EEE EESE EEES 62 Al Introduction e e En ES r Osh Gon ce tain E oy SO N R ds 62 4 2 Prerequisite S a yepe E EEEE EEE ph R EE E EE AEE EEES EEEE SEE E E 63 43 Start Ca ptUrNE ra E E EE e E EE EE E N EE metas E EN O EOE A ENE 64 4 4 The Capture Interfaces dialog DOK sin seeni nee e e EE Ena E 65 4 5 The Capture Options dialog BOX 200 0 eee ee ceec erse i ie si e 66 4 3 1 Caprare TAME s one e oieee Ee R E E bie uae se sh E A A Sten a E 66 4 5 2 Capire File s frame sen E E E a e 68 4 5 3 Sto
153. p Capture frame nisn e a E E EA E EE EE 68 4 5 4 Display Options frame eee cce ec eee cee ca cece E ESEESE EErEE A ESEESE ae 69 4 5 5 Name Resolution fraM ssri sinsero gs scdeavss sebaeeg festnesasevetesgpssdesegssebtengseesses 69 45 0 Buttons 22 jong egos cess pe ersan ys cae O EE Seagate bans sese AOE EE EOE S EATE cab ongudemaes 69 4 6 Capture files and file Modes iiion eects ssi bertasseencoa nes pata des canes sesbestensecssagy a TE 70 4 7 Link layer Header type acsvecetcss ccevoeensvuaw ce Stee geet ye cater N EE S here gentheumies scene deans E 72 4 8 Filtering While capturi te esena sees 03 poneer EE ER E EE AE ed psa esta R EE EREA 73 4 9 While a Capture 18 LUnnin E se 5 she scan e an e a E dhs e E A tego ue ederagnn thee vane T 75 4 91 Stop the running Capture 223 4 a a T E RO A ee ee 75 4 92 Restart arunnin amp Capture n s csecsses eseess wesessnased obedsvunessnyoseuess e nee 76 5 File Input Output and Printing oenn e ec EE E ES E OEA E EEES 78 Di Le Introduction icerisine aa e E T a E a O E ET E T Ra ee 78 5 2 Open capture files s iscrsisreer nepe ese truet te tivesse EEE EEVEE EIEEE ESEIA OSEE VENN cedstpeecdessseeereses 79 5 2 1 The Open Capture File dialog Dox 20 0 0 cee cee ce eeceeeceeeea teen eeea sean eeaeeeas 79 5 2 2 Input File Formats ise ionisoi Sea E OEE EEEE E EOE E EEES 80 5 3 Saving captured packets ci seciess sisenes iess aose o pp EEE S E E TEE ESEE 82 5 3 1 The Save Capture F
154. packet If you do not spe live cap cify this Ethereal simply adds new packets onto the end of the list but does not scroll ture the packet list pane This option is greyed out if Update list of packets in real time is disabled Hide cap If this option is checked the following capture info dialog will be hidden ture info dialog Name Resolution frame Enable MAC name resolution Enable network name resolution Enable transport name resolu tion Buttons This option allows you to control whether or not Ethereal translates MAC addresses into names see Section 7 6 Name Resolution This option allows you to control whether or not Ethereal translates network addresses into names see Section 7 6 Name Resolution This option allows you to control whether or not Ethereal translates transport addresses into protocols see Section 7 6 Name Resolution Once you have set the values you desire and have selected the options you need simply click on OK to commence the capture or Cancel to cancel the capture If you start a capture Ethereal allows you to stop capturing when you have enough packets cap tured for details see Section 4 9 While a Capture is running 69 Capturing Live Network Data 4 6 Capture files and file modes While capturing the underlying libpcap capturing engine will grab the packets from the network card and keep the packet data in a relatively small k
155. ple text file containing statements of the form variable value It is read at program start and written at program exit This file contains all the capture filters that you have defined and saved It consists of one or more lines where each line has the following format lt filter name gt lt filter string gt The settings from this file are read in at program start and written to disk when you press the Save button in the Cap ture Filters dialog box This file contains all the display filters that you have defined and saved It consists of one or more lines where each line has the following format lt filter name gt lt filter string gt The settings from this file are read in at program start and 168 Configuration and other Files and Folders written to disk when you press the Save button in the Dis play Filters dialog box colorfilters This file contains all the color filters that you have defined and saved It consists of one or more lines where each line has the following format lt filter name gt lt filter string gt lt bg RGB 16 bit gt lt fg RGB 16 bit gt The settings from this file are read in at program start and written to disk when you press the Save button in the Color ing Rules dialog box disabled_protos Each line in this file specifies a disabled protocol name The following are some examples tcp udp The settings from this file are read in at program s
156. pops up the Ethereal Export dialog box which is discussed further in Section 5 6 5 The Export as PDML File dialog box Export gt Selec Ctrl H ted Packet This menu item allows you to export the currently selected bytes in the Bytes packet bytes pane to a binary file It pops up the Ethereal Export dialog box which is discussed further in Section 5 6 6 The Export selected packet bytes dialog box Print Ctrl P This menu item allows you to print all or some of the packets in the capture file It pops up the Ethereal Print dialog box which is discussed further in Section 5 7 Printing packets Quit Ctrl Q This menu item allows you to quit from Ethereal Ethereal will ask to save your capture file if you haven t saved it before this can be disabled by a preference setting 36 User Interface 3 6 The Edit menu The Ethereal Edit menu contains the fields shown in Table 3 2 Edit menu items Figure 3 4 The Edit Menu test cap Ethereal DER GA View Go Capture Analyze Statistics Help Find Packet Ctrl F Si ia ae lx G DeD F Eea Find Previous Ctrl B a AP Expression Ys clear yf Apply Time Reference Set Time Reference toggle Ctrl T Mark Packet toggle Ctrl M Find Next Protocol Info Mark All Packets Find Previous RP who has 1 Unmark All Packets TIC LOO IBNS ame qu x Preferences Shift Ctrl P 224 0 0 22 V3 Membership Report lt
157. ption with n files op tion Single temporary etherXXXXXX where file XXXXXX is a unique number foo cap Single named file foo cap foo cap x Multiple files foo_00001_20040205110102 cap continuous foo_00002_20040205110102 cap foo cap x x Multiple files foo_00001_20040205110102 cap ring buffer foo_00002_20040205110102 cap Single temporary file A temporary file will be created and used this is the default After the capturing is stopped this file can be saved later un der a user specified name Single named file A single capture file will be used If you want to place the 70 Capturing Live Network Data Multiple files continuous Multiple files ring buffer new capture file to a specific folder choose this mode Like the Single named file mode but a new file is created and used after reaching one of the multiple file switch condi tions one of the Next file every values Much like Multiple files continuous reaching one of the multiple files switch conditions one of the Next file every values will switch to the next file This will be a newly created file if value of Ring buffer with n files is not reached otherwise it will replace the oldest of the formerly used files thus forming a ring This mode will limit the maximum disk usage even for an unlimited amount of capture input data keeping the latest captured data 71 Capturing Live Network Data 4 7 Lin
158. r Windows from the binary packages 2 8 1 Install Ethereal You may acquire a binary installer of Ethereal named something like ethereal setup xX y zZ exe Simply download the Ethereal installer from http www ethereal com download html releases and execute it Note Since Ethereal Version 0 10 12 the WinPcap installer has become part of the main Ethereal installer so you don t need to download and install two separate packages any longer 2 8 1 1 Command line options You can simply start the Ethereal installer without any command line parameters it will show you the usual interactive installer There are some command line parameters available e NCRC disables the CRC check e S runs the installer or uninstaller silently with default values Please note The silent installer won t install WinPCap e desktopicon installation of the desktop icon yes force installation no don t install other wise use defaults user settings This option is available since 0 10 13 an can be useful for a si lent installer e quicklaunchicon installation of the quick launch icon yes force installation no don t in stall otherwise use defaults user settings This option is available since 0 10 13 an can be use ful for a silent installer e D sets the default installation directory INSTDIR overriding InstallDir and InstallDir RegKey It must be the last parameter used in the command line and must not contain a
159. radio IEEE 802 11 Wireless LAN with radio information 181 Related command line tools Specification ieee 802 11l radiotap IEEE 802 11 plus radiotap WLAN header ne 802 11l avs IEEE 802 11 plus AVS WLAN header linux sll Linux cooked mode capture frelay Frame Relay frelay with direction Frame Relay with Directional Info chdlc Cisco HDLC ios Cisco IOS internal ltalk Localtalk pflog old OpenBSD PF Firewall logs pre 3 4 hhdlc HiPath HDLC docsis Data Over Cable Service Interfac cosine CoSine L2 debug log whdlc Wellfleet HDLC sdlc SDLC tzsp Tazmen sniffer protocol nc OpenBSD enc 4 encapsulating interface pflog OpenBSD PF Firewall logs chdlc with direction Cisco HDLC with Directional Info bluetooth h4 Bluetooth H4 mtp2 SS7 MTP2 mtp3 SS7 MTP3 irda IrDA user0Q USER 0 userl USER 1 user2 USER 2 user3 USER 3 user4 USER 4 user5 USER 5 user6 USER 6 user7 USER 7 user8 USER 8 user9 USER 9 userl0 USER 10 userll USER 11 userl2 USER 12 userl3 USER 13 userl4 USER 14 userl5 USER 15 symantec Symantec Enterprise Firewall ap1394 Apple IP over IEEE 1394 bacnet ms tp BACnet MS TP raw icmp n raw icmpv6 gprs lle juniper at juniper at redback rawip nett EL Raw ICMP with nettl h
160. re allowed only for noncom received the program in an offer in accord wit he information you rece nding source code Th mercial distribution a object code or execut h Subsection b above The source code making modifica code means all for a work means the preferred fo tions to it For an executable wo the source code for all modules it associated interface definition files plus the s control compilation and installation of the execu special exception the source code distributed ne anything that is normally distributed in either form with the major components compiler kernel operating system on which the executable runs un itself accompanies the executable If distribu access to copy from a designated place then off rms of Sections 1 and 2 above o r software interchange or or at least three no more than your tion a complete urce code to be n a medium T offer is ived as to the is alternative nd only if you able form with such rm of the work for rk complete source contains plus any cripts used to table However as a ed not include source or binary and so on of the F less that component tion of executable or object code is made by offering access to copy the source code from the same plac distribution of the source code even though thir compelled to copy the source along with the object 4 You may not copy modify sublicense or dis e
161. reaks out there 3 HEX Dump This allows you to see all the data This will require a lot of screen space and is best used with binary protocols 4 C Arrays This allows you to import the stream data into your own C program 5 Raw This allows you to load the unaltered stream data into a different program for further ex amination The display will look the same as the ASCII setting but Save As will result in a binary file 124 Advanced Topics 7 3 Time Stamps 7 3 1 7 3 2 7 3 3 Time stamps their precisions and all that can be quite confusing this section will provide you with information what s going on while Ethereal processes time stamps While packets are captured each packet is time stamped as it comes in These time stamps will be saved to the capture file so they also will be available for later analysis So where do these time stamps come from While capturing Ethereal gets the time stamps from the libpcap WinPcap library which in turn get s them from the operating system kernel If the capture data is loaded from a capture file Ethereal obviously gets the data from that file Ethereal internals The internal format that Ethereal uses to keep a packet time stamp consists of the date in days since 1 1 1970 and the time of day in nanoseconds since midnight You can adjust the way Ethereal dis plays the time stamp data in the packet list see the Time Display Format item in the Section 3 7
162. real ETHEREAL ipxnets tion ipxnets plugins Plugin directories ETHEREAL plugins lt version gt ust APPDATA Ethereal plugins share ethere al plugins ust loc al share ethere al plugins HOME ethereal plugins 167 Configuration and other Files and Folders File Folder Description Unix Linux Windows folders folders temp Temporary files _ Environment Environment TMPDIR or TEMP TMPDIR Windows folders APPDATA points to the personal configuration folder typically C Documents and Settings lt username gt Application Data for further details have a look at Section A 1 1 Windows profiles 7ETHEREAL points to the Ethereal program folder typically C Program Files Ethereal Unix Linux folders The etc folder is the global Ethereal configuration folder The folder actually used on your system may vary maybe something like usr local etc preferences ethereal conf recent cfilters dfilters This file contains your Ethereal preferences including de faults for capturing and displaying packets It is a simple text file containing statements of the form variable value The settings from this file are read in at program start and written to disk when you press the Save button in the Prefer ences dialog box This file contains various GUI related settings like the main window position and size the recent files list and such It is a sim
163. rmat gt Selecting this tells Ethereal to display time stamps with a precision of seconds 0 one second decisecond centisecond millisecond microsecond or nano second see Section 6 9 Time display formats and time references Name Resolu tion gt Resolve Name This item allows you to trigger a name resolve of the current packet only see Section 7 6 Name Resolution Name Resolu tion gt Enable for MAC Layer This item allows you to control whether or not Ethereal translates MAC addresses into names see Section 7 6 Name Resolution Name Resolu tion gt Enable This item allows you to control whether or not Ethereal translates net 40 User Interface Menu Item Accelerator Description for Network Layer work addresses into names see Section 7 6 Name Resolution Name Resolu tion gt Enable This item allows you to control whether or not Ethereal translates trans for Transport port addresses into names see Section 7 6 Name Resolution Layer Colorize Packet List This item allows you to control wether or not Ethereal should colorize the packet list Note Enabling colorization will slow down the display of new packets while capturing loading capture files Auto Scroll in Live Capture This item allows you to specify that Ethereal should scroll the packet list pane as new packets come in so you are always lookin
164. rnel buffer which will keep the captured packets until they are written to disk If you encounter packet drops try increasing this value Note This option is only available on Windows plat forms This checkbox allows you to specify that Ethereal should put the interface in promiscuous mode when capturing If you do not specify this Ethereal will only capture the packets going to or from your computer not all packets on your LAN seg ment Note If some other process has put the interface in promiscuous mode you may be capturing in promiscuous mode even if you turn off this op tion Note Even in promiscuous mode you still won t ne cessarily see all packets on your LAN segment see http www ethereal com fag promiscsniff for some more explanations This field allows you to specify the maximum amount of data that will be captured for each packet and is sometimes re ferred to as the snaplen If disabled the default is 65535 which will be sufficient for most protocols Some rules of thumb e If you are unsure just keep the default value e Ifyou don t need all of the data in a packet for example if you only need the link layer IP and TCP headers you might want to choose a small snapshot length as less 67 Capturing Live Network Data Capture Filter CPU time is required for copying packets less buffer space is required for packets and thus perhaps fewer packets will be dropped if traffic i
165. rst Packet 2003 12 09 10 32 59 Elapsed time 00 00 32 Enable network name resolution Enable transport name resolution eoon a cons With this dialog box you can perform the following actions 1 The Add button allows you to add a directory selected in the right hand pane to the favor ites bookmarks list Those changes are persistent 2 The Remove button allows you to remove a selected directory from that list again the items like Home Desktop and Filesystem cannot be removed 3 Select files and directories with the list boxes 4 View file preview information like the filesize the number of packets while browsing the filesystem 5 Specify a display filter with the Filter button and filter field This filter will be used when open ing the new file Clicking on the Filter button causes Ethereal to pop up the Filters dialog box which is discussed further in Section 6 2 Filtering packets while viewing 6 Specify which name resolution is to be performed for all packets by clicking on one of the En able name resolution check buttons Details about name resolution can be found in Sec tion 7 6 Name Resolution 7 Click the Open button to accept your selected file and open it If Ethereal doesn t recognize the capture format it will grey out this button 8 Click the Cancel button to go back to Ethereal and not load a capture file You can also change the display
166. rt Capturing and al lows you to start capturing packets Start Capture Start This item starts capturing packets with the options form the last time Stop Capture Stop This item stops the currently running live capture process Section 4 3 Start Capturing Restart Capture Restart This item stops the currently running live capture process and restarts it again for convenience Open File Open This item brings up the file open dialog box that allows you to load a capture file for viewing It is discussed in more de tail in Section 5 2 1 The Open Capture File dialog box Save As File Save As This item allows you to save the current capture file to whatever file you would like It pops up the Save Capture File As dialog box which is discussed further in Sec tion 5 3 1 The Save Capture File As dialog box Note If you currently have a temporary capture file the Save icon will be shown instead Close File Close This item closes the current capture If you have not saved the capture you will be asked to save it first 53 User Interface Toolbar Toolbar Item Corresponding Description Icon Menu Item TA Reload View Reload p This item allows you to reload the current capture file E Print File Print el This item allows you to print all or some of the packets in the capture file It pops up the Ethereal Print dialog box whic
167. s the capture data is spreaded over several capture files called a file set As it can become tedious to work with a file set by hand Ethereal provides some features to handle these file sets in a convenient way How does Fthereal detect the files of a file set A filename in a file set uses the format Prefix_Number_DateTimeSuffix which might look like this test_00001_20060420183910 pcap All files of a file set share the same prefix e g test and suffix e g peap and a varying middle part To find the files of a file set Ethereal scans the directory where the currently loaded file resides and scans for files matching the same filename pattern prefix and suffix than the currently loaded file This simple mechanism usually works well but has it s drawbacks If several file sets were captured with the same prefix and suffix Ethereal will detect them as a single file set If files were renamed or spreaded over several directories the mechanism will fail to find all files of a set The following features in the File Set submenu of the File menu are available to work with file sets in a convenient way e The List Files dialog box will list the files Ethereal has recognized as being part of the current file set e Next File closes the current and opens the next file in the file set e Previous File closes the current and opens the previous file in the file set 5 5 1 The List Files dialog box Figure 5 4 The
168. s clear Apply The leftmost button labeled Filter can be clicked to bring up the filter construction dialog de scribed in Figure 6 8 The Capture Filters and Display Filters dialog boxes e The left middle text box provides an area to enter or edit display filter strings see Section 6 3 Building display filter expressions A syntax check of your filter string is done while you are typing The background will turn red if you enter an incomplete or invalid string and will be come green when you enter a valid string You can click on the pull down arrow to select a pre viously entered filter string from a list The entries in the pull down list will remain available even after a program restart Note After you ve changed something in this field don t forget to press the Apply button or the Enter Return key to apply this filter string to the display Note This field is also where the current filter in effect is displayed e The middle button labeled Add Expression opens a dialog box that lets you edit a display fil ter from a list of protocol fields described in Section 6 4 The Filter Expression dialog box e The right middle button labeled Clear resets the current display filter and clears the edit area e The rightmost button labeled Apply applies the current value in the edit area as the new dis play filter Note Applying a display filter on large capture files might take quite
169. s very heavy e If you don t capture all of the data in a packet you might find that the packet data you want is in the part that s dropped or that reassembly isn t possible as the data re quired for reassembly is missing This field allows you to specify a capture filter Capture fil ters are discussed in more details in Section 4 8 Filtering while capturing It defaults to empty or no filter You can also click on the button labelled Capture Filter and Ethereal will bring up the Capture Filters dialog box and al low you to create and or select a filter Please see Section 6 5 Defining and saving filters 4 5 2 Capture File s frame An explanation about capture file usage can be found in Section 4 6 Capture files and file modes File Use multiple files Next file every n megabyte s Next file every n minute s Ring buffer with n files Stop capture after n file s This field allows you to specify the file name that will be used for the capture file This field is left blank by default If the field is left blank the capture data will be stored in a tem porary file see Section 4 6 Capture files and file modes for details You can also click on the button to the right of this field to browse through the filesystem Instead of using a single file Ethereal will automatically switch to a new one if a specific trigger condition is reached Multiple files only Switch to th
170. select the page you want to see Figure 3 16 The Packet Bytes pane with tabs 06 6b 7f 0010 01 48 33 c7 00 OO 1e 11 dd 51 bc ag 08 Oa bc as 0020 09 32 41 af OF 04 01 34 OO b4 04 OO 2e OO 10 OO 97 6c di 11 82 Frame 342 bytes Reassembled DCE RPC 1604 bytes Note The additional pages might contain data picked from multiple packets The context menu right mouse click of the tab labels will show a list of all available pages This can be helpful if the size in the pane is too small for all the tab labels 59 User Interface 3 18 The Statusbar The statusbar displays informational messages In general the left side will show context related information while the right side will show the cur rent number of packets Figure 3 17 The initial Statusbar Ready to load or capture No Packets y This statusbar is shown while no capture file is loaded e g when Ethereal is started Figure 3 18 The Statusbar with a loaded capture file The left side shows information about the capture file its name its size and the elapsed time while it was being captured The right side shows the current number of packets in the capture file The following values are dis played e P the number of captured packets e D the number of packets currently being displayed e M the number of marked packets Figure 3 19 The Statusbar with a selected protocol field opcode arp opcode 2bytes 7 i PazaoDnamon S S7
171. ses e t nE EE E EEE EE E TEE ES 1 1127 Features r a n hl hes E a e E E e E E oceans cues tent sue lee tase geet eo 1 1 1 3 Live capture from many different network media ee cece eceeeeeee ee eeee teen eenes 2 1 1 4 Import files from many other capture programs cceeeeeeeeeeeeeeeneeeeeereeenereees 2 1 1 5 Export files for many other capture programs 0 ccc ceee cece cee ceeeeeeeea seca seen eeues 2 11 6 Many protocol decoders si isinin enne vasetuedsauotebsssbestistesaatapeetueaseenetes 2 1 1 7 Open Source SoftWare ssrosscsivssrerpseis costes oe ssisueeeos dane cassonvecesssawesdesrpemewestayeceeseyy 2 1 1 8 What Ethereal iS TOt sissioni resien ers esi nae vE ER di etaadeseomacaneseteageeedoons 3 1 2 Platforms Ethereal fUnSOn mrene nene a E eE e tas E eee feats hs 4 VD T UMR a e ne eh Lait nee ete E a S E E EE SSN 4 1 2 2 Link eee ea R E SE E EEA EEEN EE N EIE PETAR 4 2 3 Microsoft WandOWS senit ee ee ETA E E EE shee IRER 5 1 3 Where fo get Ethereal 2 4o issovee nea e E E E E E A AES 6 1 4 A rose by any other name neesii nieo nE EEE EE EEES EEEE 7 1 5 A brief history of Ethereal gsis nsir irrist sons eo EE EGA AES n RE SPONE ETE S EEE POPAS IPERE 8 1 6 Development and maintenance of Ethereal se sseesssseessrerssrerrsresrrsrerrsrrerrrresrrersrreees 9 1 7 Reporting problems and getting help 2 2 0 0 cece eeceeeceeeceeeceeeeaeecaeeea essa eens eeaeeegs 10 F71 Website eirmse te beets lot
172. set a display filter to reduce the amount of packets 147 Statistics Figure 8 7 The DCE RPC Statistic for window DCE RPC Service Response Time statistics for EPM major version 3 test DCE RPC Service Response Time statistics for EPM major version 3 test cap Filter ndex Procedure Cals in SRT lax SRT Avg SRT Insert 0 00000 0 00000 0 00000 Delete 0 00000 0 00000 0 00000 Lookup 0 00000 0 00000 0 00000 Map 0 00000 0 00000 0 00000 LookupHandleFree 0 00000 0 00000 0 00000 IngObject 0 00000 0 00000 0 00000 MgmtDelete 0 00000 0 00000 0 00000 Each row corresponds to a method of the interface selected so the EPM interface in version 3 has 7 methods For each method the number of calls and the statistics of the SRT time is calculated 148 Statistics 8 8 The protocol specific statistics windows The protocol specific statistics windows display detailed information of specific protocols and might be described in a later version of this document Some of these statistics are described at the http wiki ethereal com Statistics pages 149 Statistics 150 Chapter 9 Customizing Ethereal 9 1 Introduction Ethereal s default behaviour will usually suit your needs pretty well However as you become more familiar with Ethereal it can be customized in various ways to suit your needs even better In this chapter we explore e How to start Ethereal with command line parameters
173. soto enen siden e beh ogg EEE E ce ea ened O a 174 GAA Maltormed Packet E EAE TEE E E AN 174 C 1 2 Packet size limited during capture 2 0 0 0 eee cee cence eece eee eeeeeeeeeeeaeeenes 174 C2 Packet Details Messages ciinei naa esna ea e E E vas apeas ses D EE 175 C 2 1 Response in frame 123 soc deccitvecscivenseadety ekee ra Ee S A ne Kinie 175 C22 Request in frame 123 odes doses iaa an ae E AE sae PERIERE POLES PAREA i 175 C 2 3 Time from request 0 123 seconds s sisseseseeseseereresesrsessesesesrereeeresrsrereses 175 D Related command line tools 2 00 0 iroi i rei iE E EE EEE EEE EEE E 177 Dh SIMMTOGUCHON ieaie aee a e a aar a e i eo 177 D 2 tcpdump Capturing with tcpdump for viewing with Ethereal 0 0 0 0 eee 178 D 3 tethereal Terminal based Ethereal eee ee eee ceee ce eece ceca cena eens een eeneeeeeeeenes 179 D 4 capinfos Print information about capture files 0 0 00 eee eeeeeeeeceeececeeeeeueeeeeeecennereene ees 180 DS editcapsEdit capture f1leS iccc ces cde pheegecentwoctis pyounaisstwsae phephvtmess syed yahesh betes Cesar EE KSE 181 D 6 mergecap Merging multiple capture files into ONE 2 00 0 le eee ee ce ee ce ee ce eeeeeeeeeeeeees 184 D 7 text2pceap Converting ASCII hexdumps to network captures eceeeeeeeeeceeeeeeeee eee 187 D 8 idl2eth Creating dissectors from Corba IDL files 2 0 0 0 eee cece eeeeceeneeceeeeeeeeeenneeeeaeeeee 190 D851 What 18
174. srreersrrersrrerrerrerrereerere 128 74 2 Ether aland Time ZONES hitsa eaa E a E AAEE aa 128 75 Packet REASSEMDUNG orsono taen a Ee test E ES Ep sean ERESIA eters SE 130 FSk Whatis Mi a E A E N EE e see Mech aS EES R E E 130 7 5 25 HOW Ethereal handles it wisi ans csaesad eek tea dencddas auc tanend ook See Gace deee erect ea eetes 130 7 6 Name Resolution 23 3 sic sevens elas eee dade ead el ve vata ded TE E bea edaa E ER abated oe wenden tees 132 7 6 1 Name Resolution drawbacks ccececeseceecneceeeeeeeeeeceeeeecaeeeeeeenereeesereeaneres 132 7 6 2 Ethernet name resolution MAC layer ceceeeeseeeeeeeceecnereeeeereseereeeeereeanenes 132 7 6 3 IP name resolution network layer ceceeeceecneceeeneceeeeeeeeeeeeeeereeaeresenenes 133 7 6 4 IPX name resolution network layer cee ceeeseceeeeeceeeeceeeeeeeceereseereeenenes 133 7 6 5 TCP UDP port name resolution transport layer cece cece ceeeceee ee eeeeeeeeeenee 133 Pike CHECKSUMS erisir ed ave ye hewak e ce aa gloves AE Slee E E a S ga tork ws 134 7 7 1 Ethereal checksum validation sininen e n E T Ea 134 77 2 Checksum offloading iristerik ensei eniri ese 134 Ss Statistics anrea EEE EREN TE ARETE EA A ENESE EEE Saupe end AE TEN EEEN ewes EE 137 amp 1 Mmtrod ction s sean n a e a a ven deb eee aaa e eet a aa a Aa 137 8 2 The Summary MVO A ee lee A E ce EN ARRES 138 8 3 The Protocol Hierarchy window sorria see a e AEE E T SANE
175. ssector for this packet This will happen e g if you are using a protocol not on it s well known TCP or UDP port You may try AnalyzelDecode As to circumvent this problem e Packet not reassembled The packet is longer than a single frame and it is not reassembled see Section 7 5 Packet Reassembling for further details e Packet is malformed The packet is actually wrong malformed meaning that a part of the packet is just not as expected not following the protocol specifications e Dissector is buggy The corresponding protocol dissector is simply buggy or still incomplete Any of the above is possible You ll have to look into the specific situation to determine what it is You could disable the dissector by disabling the protocol on the Analyze menu and check how Eth ereal displays the packet then You could if it s TCP enable reassembly for TCP and the specific dissector if possible in the EditlIPreferences menu You could check the packet contents yourself by reading the packet bytes and comparing it to the protocol specification This could reveil a dis sector bug Or you could find out that the packet is indeed wrong C 1 2 Packet size limited during capture The packet size was limited during capture see Limit each packet to n bytes at the Section 4 5 The Capture Options dialog box While dissecting the current protocol dissector was simply running out of packet bytes and had to give up There s nothing else
176. t You can filter on any protocol that Ethereal understands You can also filter on any field that a dis sector adds to the tree view but only if the dissector has added an abbreviation for the field A list of such fields is available in the Ethereal in the Add Expression dialog box You can find more in formation on the Add Expression dialog box in Section 6 4 The Filter Expression dialog box For example to narrow the packet list pane down to only those packets to or from the IP address 192 168 0 1 use ip addr 192 168 0 1 Note To remove the filter click on the Clear button to the right of the filter field 106 Working with captured packets 6 3 Building display filter expressions 6 3 1 6 3 2 Ethereal provides a simple but powerful display filter language that you can build quite complex fil ter expressions with You can compare values in packets as well as combine expressions into more specific expressions The following sections provide more information on doing this Tip You will find a lot of Display Filter examples at the Ethereal Wiki Display Filter page at http wiki ethereal com DisplayFilters Display filter fields Every field in the packet details pane can be used as a filter string this will result in showing only the packets where this field exists For example the filter string tep will show all packets contain ing the tcp protocol There is a complete list
177. t delimiter must be specified but no pattern is required the remaining numbe is assumed to be fractions of a second w lt filename gt Write the capture file generated by text2pcap to lt filename gt The de fault is to write to standard output h Display the help message d Displays debugging information during the process Can be used multiple times to generate more debugging information q Be completely quiet during the process 0 hexloct Specify the radix for the offsets hex or octal Defaults to hex This corresponds to the A option for od l Specify the link layer type of this packet Default is Ethernet 1 See net bpf h for the complete list of possible encapsulations Note that this option should be used if your dump is a complete hex dump of an encapsulated packet and you wish to specify the exact type of en capsulation Example 1 7 for ARCNet packets 188 Related command line tools e I3pid u srcport destport Include a dummy Ethernet header before each packet Specify the L3PID for the Ethernet header in hex Use this option if your dump has Layer 3 header and payload e g IP header but no Layer 2 en capsulation Example e 0x806 to specify an ARP packet For IP packets instead of generating a fake Ethernet header you can also use l 12 to indicate a raw IP packet to Ethereal Note that 1 12 does not work for any non IP Layer 3 packet e g
178. ta from Ethereal Note There are more specialized functions to export specific data which will be described at the appropriate places XXX add detailed descriptions of the output formats and some sample output too 5 6 1 The Export as Plain Text File dialog box Export packet data into a plain ASCII text file much like the format used to print packets Figure 5 5 The Export as Plain Text File dialog box Ethereal Export as Plain Text File Export to file Packet Range Packet Format Captured Displayed Packet summary line All packets 191 Packet details Selected packet only 1 Allcollapsed As displayed All expanded Specify a packet range C Packet bytes _ Each packet on a new page e Export to file frame chooses the file to export the packet data to e The Packet Range frame is described in Section 5 8 The Packet Range frame e The Packet Details frame is described in Section 5 9 The Packet Format frame 5 6 2 The Export as PostScript File dialog box Export packet data into PostScript much like the format used to print packets 89 File Input Output and Printing Tip N You can easily convert PostScript files to PDF files using ghostscript For example export to a file named foo ps and then call ps2pdf foo ps Figure 5 6 The Export as PostScript File dialog box Ethereal Export as PostScript
179. tails pane 47 User Interface Menu Item Accelerator Description Enabled Proto Shift Ctrl R cols This menu item allows the user to enable disable protocol dissectors see Section 9 4 1 The Enabled Protocols dialog box Decode As This menu item allows the user to force Ethereal to decode certain pack ets as a particular protocol see Section 9 4 2 User Specified Decodes User Specified Decodes This menu item allows the user to force Ethereal to decode certain pack ets as a particular protocol see Section 9 4 3 Show User Specified De codes Follow TCP Stream This menu item brings up a separate window and displays all the TCP segments captured that are on the same TCP connection as a selected packet see Section 7 2 Following TCP streams 48 User Interface 3 11 The Statistics menu The Ethereal Statistics menu contains the fields shown in Table 3 7 Statistics menu items Figure 3 9 The Statistics Menu test cap Ethereal File Edit Yiew Go Capture Analyze A Se il Of Cia amp gee DZ Eie Conversations ilter A Endpoints Source 10 Graphs Conversation List Endpoint List 4 0 726445 192 168 0 2 onse Time ANSI GSM H 225 ISUP Message Types MTP3 Bae PDFs BIG QQ Ne P Expression Yi clear Apply Protocol Info ARP who has DCE RPC
180. tamps itself but simply get s them from somewhere else and displays them So ac curacy will depend on the capture system operating system performance that you use Because of this the above question is difficult to answer in a general way Note USB connected network adapters often provide a very bad time stamp accuracy The incoming packets have to take a long and winding road to travel through the USB cable until they actually reach the kernel As the incoming packets are time stamped when they are processed by the kernel this time stamping mechanism becomes very 125 Advanced Topics inaccurate Conclusion don t use USB connected NIC s when you need precise time stamp accur acy XXX are there any such NIC s that stamps already on the USB hardware 126 Advanced Topics 7 4 Time Zones If you travel across the planet time zones can be confusing If you get a capture file from some where around the world time zones can even be a lot more confusing First of all there are two reasons why you may not need to think about time zones at all e You are only interested in the time differences between the packet time stamps and don t need to know the exact date and time of the captured packets which is often the case e You don t get capture files from different time zones than your own so there are simply no time zone problems For example everyone in your team is working in the same time zone tha
181. tart and written to disk when you press the Save button in the En abled Protocols dialog box ethers When Ethereal is trying to translate Ethernet hardware ad dresses to names it consults the files listed in Table A 1 Configuration files and folders overview If an address is not found in etc ethers Ethereal looks in HOME ethereal ethers Each line in these files consists of one hardware address and name separated by whitespace The digits of hardware ad dresses are separated by colons dashes or periods The following are some examples EE EEF SPE SLE LES EE Broadcast c0 00 f f f f ff L E TR_broadcast 00 2b 08 93 4b al Freds_machine The settings from this file are read in at program start and never written by Ethereal manuf Ethereal uses the files listed in Table A 1 Configuration files and folders overview to translate the first three bytes of an Ethernet address into a manufacturers name This file has the same format as the ethers file except addresses are three bytes long An example is 00 00 01 Xerox XEROX CORPORATION The settings from this file are read in at program start and never written by Ethereal 169 Configuration and other Files and Folders hosts Ethereal uses the files listed in Table A 1 Configuration files and folders overview to translate IPv4 and IPv6 ad dresses into names This file has the same format as the usual e
182. tation format of this timestamp can be changed see Section 6 9 Time display formats and time references e Source The address where this packet is coming from e Destination The address where this packet is going to e Protocol The protocol name in a short perhaps abbreviated version Info Additional information about the packet content There is a context menu right mouse click available see details in Figure 6 3 Pop up menu of Packet List pane 57 User Interface 3 16 The Packet Details pane The packet details pane shows the current packet selected in the Packet List pane in a more de tailed form Figure 3 14 The Packet Details pane Frame 1 42 bytes on wire 42 bytes captured Ethernet II src 192 168 0 2 O0 0b Sd 20 cd 02 Ost Broadcast ff ff ff ff ff fh Address Resolution Protocol request gratuitous ARP e This pane shows the protocols and protocol fields of the packet selected in the Packet List pane The protocols and fields of the packet are displayed using a tree which can be expanded and col lapsed There is a context menu right mouse click available see details in Figure 6 4 Pop up menu of Packet Details pane Some protocol fields are specially displayed e Generated fields Ethereal itself will generate additional protocol fields which are surrounded by brackets The information in these fields is derived from the known context to o
183. tc hosts file in unix systems An example is Comments must be prepended by th sign 192 168 0 1 homeserver The settings from this file are read in at program start and never written by Ethereal ipxnets Ethereal uses the files listed in Table A 1 Configuration files and folders overview to translate IPX network numbers into names An example is CO A8 2C 00 HR c0 a8 1c 00 CEO 00 00 BE EF IT_Server1 110 FileServer3 The settings from this file are read in at program start and never written by Ethereal plugins folder Ethereal searches for plugins in the directories listed in Ta ble A 1 Configuration files and folders overview They are searched in the order listed temp folder If you start a new capture and don t specify a filename for it Ethereal uses this directory to place that file in see Sec tion 4 6 Capture files and file modes A 1 Windows folders Here you will find some details about the folders used in Ethereal on different Windows versions As already mentioned you can find the currently used folders in the About Ethereal dialog A 1 1 Windows profiles Windows uses some special directories to store user configuration files in named the user profile This can be confusing as the default directory location changed from version to version and might also be different for english and internationalized versions of windows Note If you
184. ted by this packet or the request for which this packet is a response Copy bH IX J Copy the selected packet data to the clipboard XXX in which format x lt Export Selected File gt Export Packet Bytes Export raw packet bytes to a binary file Figure 6 3 Pop up menu of Packet List pane test cap Ethereal DAR File Edit Yiew Go Capture Analyze Statistics Help BHa ae cM xcr eS ger vmrFt Bag eter expression Ysclear Y apply No Time Source Destination Protocol Info 30 TACK Seg 1 Ack 1 Wi Mark Packet toggle va a rT Time Reference Set Time Reference toggle Find Next Apply as Filter Find Previous Prepare a Filter Frame 23 60 bytes on wire 60 bytes captured Follow TCP Stream Ethernet II Src Netgear_2d 75 9a O0 09 Sbi2d 75 4 b Sd 20 cd 02 Internet Protocol Src 192 168 0 1 192 168 0 1 q 23 Decode As 22 Transmission Control Protocol Src Port 1025 1025 E Print eq 1 Ack 1 Len 0 Source port 1025 1025 E sooo 5000 Show Packet in New Window Destination port Sequence number 1 Crelative sequence number Acknowledgement number 1 relative ack number Header length 20 bytes J Flags 0x0010 ACK Window size 3072 Checksum Oxe797 correct SEQ ACK analysis cd 02 00 09 9a 08 00 45 00 oo 00 40 06 as 00 01 cO as 13 88 00 00 37 7f a7 50 10 00 00 00 00 oo File ieoa test cap 14 KB 00 00 02 P 120 D 120M 0
185. tem brings up an information window that provides some in formation on Ethereal such as the plugins the used folders 51 User Interface Note Calling a Web browser might be unsupported in your version of Ethereal If this is the case the corresponding menu items will be hidden Note If calling a Web browser fails on your machine maybe because just nothing happens or the browser is started but no page is shown have a look at the webbrowser setting in the preferences dialog 52 User Interface 3 13 The Main toolbar The main toolbar provides quick access to frequently used items from the menu This toolbar cannot be customized by the user but it can be hidden using the View menu if the space on the screen is needed to show even more packet data As in the menu only the items useful in the current program state will be available The others will be greyed out e g you cannot save a capture file if you haven t loaded one Figure 3 11 The Main toolbar GHAWeH OB eS HerwMFs OS QQe Table 3 9 Main toolbar items Toolbar Toolbar Item Corresponding Description Icon Menu Item Interfaces Capture Inter faces This item brings up the Capture Interfaces List dialog box discussed further in Section 4 3 Start Capturing Options Capture Options This item brings up the Capture Options dialog box discussed further in Section 4 3 Sta
186. tended to save some daylight during the summer months To do this a lot of countries but not all add an DST hour to the already existing UTC offset So you may need to take another hour or in very rare cases even two hours difference into your time zone calculations Unfortunately the date at which DST actually takes effect is different throughout the world You may also note that the northern and southern hemispheres have opposite DST s e g while it s summer in Europe it s winter in Australia Keep in mind UTC remains the same all year around regardless of DST Further information can be found at http en wikipedia org wiki Daylight saving Further time zone and DST information can be found at http wwp greenwichmeantime com and http www timeanddate com worldclock 127 Advanced Topics 7 4 1 Set your computer s time correct 7 4 2 If you work with people around the world it s very helpful to set your computer s time and time zone right You should set your computers time and time zone in the correct sequence 1 Set your time zone to your current location 2 Set your computer s clock to the local time This way you will tell your computer both the local time and also the time offset to UTC 3 Tip If you travel around the world it s an often made mistake to adjust the hours of your computer clock to the local time Don t adjust the hours but your time zone setting in stead For your co
187. tes enable the output of the packet bytes just as in the Packet Bytes pane e Each packet on a new page put each packet on a separate page e g when saving printing to a text file this will put a form feed character between the packets 97 File Input Output and Printing 98 Chapter 6 Working with captured packets 6 1 Viewing packets you have captured Once you have captured some packets or you have opened a previously saved capture file you can view the packets that are displayed in the packet list pane by simply clicking on a packet in the packet list pane which will bring up the selected packet in the tree view and byte view panes You can then expand any part of the tree view by clicking on the plus sign the symbol itself may vary to the left of that part of the payload and you can select individual fields by clicking on them in the tree view pane An example with a TCP packet selected is shown in Figure 6 1 Ethereal with a TCP packet selected for viewing It also has the Acknowledgment number in the TCP header se lected which shows up in the byte view as the selected bytes Figure 6 1 Ethereal with a TCP packet selected for viewing test cap Ethereal File Edit Yiew Go Capture Analyze Statistics Help TI OB ESS Re VF 2 BGQQ eter expression Ysclear Y apply No Time Source Destination Protocol Info 23 0 001026 192 168 0 1 192 168 0 2 1025 gt 5000 ACK
188. the color choices however feel free to choose your own Figure 9 4 Using color filters with Ethereal File Edit Yiew Go Capture Analyze Statistics Help TUUA SBx eS QevmF LE EG QQ DZ Eiter Po i 4 Expression Ys dear yf Apply a No Time Source Destination Protocol Info 1 0 000000 19 2 Broadcast ARP Who has 192 1 FETA 4 0 726445 192 168 0 2 224 0 0 22 IGMP V3 Membership Report lt Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O00 0b S5d 20 cd 02 Ost Broadcast ff ff ff ff ff fh Address Resolution Protocol request gratuitous ARP g E ff ff ff ff ff ff 00 Ob Sd 20 cd 02 08 06 OO 01 0010 08 OO 06 04 OO 01 00 Ob Sd 20 cd 02 cO ag 00 02 0020 00 00 00 00 00 00 cO ag 00 02 test cap 14 KB 00 00 02 P 120 D 120 M 0 159 Customizing Ethereal 9 4 Control Protocol dissection 9 4 1 The user can control how protocols are dissected Each protocol has its own dissector so dissecting a complete packet will typically involve several dissectors As Ethereal tries to find the right dissector for each packet using static routes and heuristics guessing it might choose the wrong dissector in your specific case For example Eth ereal won t know if you use a common protocol on an uncommon TCP port e g using HTTP on TCP port 800 instead of the standard port 80 There are two ways to control the relations between pro
189. ther packets in the capture file For example Ethereal is doing a sequence acknowledge analysis of each TCP stream which is displayed in the SEQ ACK analysis fields of the TCP protocol e Links If Ethereal detected a relationship to another packet in the capture file it will generate a link to that packet Links are underlined and displayed in blue If double clicked Ethereal jumps to the corresponding packet 58 User Interface 3 17 The Packet Bytes pane The packet bytes pane shows the data of the current packet selected in the Packet List pane in a hexdump style Figure 3 15 The Packet Bytes pane 0000 Tf TF TT TF TF TF 00 Ob Sd 20 cd 02 08 06 00 Ol weeee eee J socnoo 0010 08 00 06 04 00 01 00 Ob Sd 20 cd 02 cO aS OO O2 J ss 0020 OO 00 00 00 00 00 cO as 00 OF ne sa As usual for a hexdump the left side shows the offset in the packet data in the middle the packet data is shown in a hexadecimal representation and on the right the corresponding ASCII characters or if not appropriate are displayed There is a context menu right mouse click available see details in Figure 6 5 Pop up menu of Packet Bytes pane Depending on the packet data sometimes more than one page is available e g when Ethereal has reassembled some packets into a single chunk of data see Section 7 5 Packet Reassembling In this case there are some additional tabs shown at the bottom of the pane to let you
190. thereal announce This mailing list will inform you about new program releases which usually appear about every 4 8 weeks ethereal users This list is for users of Ethereal People post questions about building and using Ethereal others hopefully provide answers ethereal dev This list is for Ethereal developers If you want to start developing a protocol dissector join this list You can subscribe to each of these lists from the Ethereal web site http www ethereal com Simply select the mailing lists link on the left hand side of the site The lists are archived at the Eth ereal web site as well b Tip You can search in the list archives to see if someone asked the same question some time before and maybe already got an answer That way you don t have to wait until someone answers your question Introduction 1 7 5 Reporting Problems Note Before reporting any problems please make sure you have installed the latest version of Ethereal When reporting problems with Ethereal it is helpful if you supply the following information 1 The version number of Ethereal and the dependent libraries linked with it eg GTK etc You can obtain this with the command ethereal v 2 Information about the platform you run Ethereal on 3 A detailed description of your problem 4 Ifyou get an error warning message copy the text of that message and also a few lines before and after it if there are some so others may find t
191. these topics can be found at the Ethereal Wiki at http wiki ethereal com By reading this book you will learn how to install Ethereal how to use the basic elements of the graphical user interface like the menu and what s behind some of the advanced features that are maybe not that obvious at first sight It will hopefully guide you around some common problems that frequently appears for new and sometimes even advanced users of Ethereal Preface 3 Acknowledgements The authors would like to thank the whole Ethereal team for their assistance In particular the au thors would like to thank e Gerald Combs for initiating the Ethereal project and funding to do this documentation e Guy Harris for many helpful hints and a great deal of patience in reviewing this document e Gilbert Ramirez for general encouragement and helpful hints along the way The authors would also like to thank the following people for their helpful feedback on this docu ment e Pat Eyler for his suggestions on improving the example on generating a backtrace e Martin Regner for his various suggestions and corrections e Graeme Hewson for a lot of grammatical corrections The authors would like to acknowledge those man page and README authors for the ethereal project from who sections of this document borrow heavily e Scott Renfro from whose mergecap man page Section D 6 mergecap Merging multiple cap ture files into one is derived e
192. thm is CRC32 The checksum algorithm actually chosen for a specific network protocol will depend on the expected error rate of the network medium the importance of error detection the processor load to perform the calculation the performance needed and many other things Further information about checksums can be found at http en wikipedia org wiki Checksum 7 7 1 Ethereal checksum validation Ethereal will validate the checksums of several potocols e g IP TCP It will do the same calculation as a normal receiver would do and shows the checksum fields in the packet details with a comment e g correct invalid must be 0x12345678 or alike Checksum validation can be switched off for various protocols in the Ethereal protocol preferences e g to very slightly increase performance If the checksum validation is enabled and it detected an invalid checksum features like packet reas sembling won t be processed This is avoided as incorrect connection data could confuse the in ternal database 7 7 2 Checksum offloading The checksum calculation might be done by the network driver protocol driver or even in hardware For example The Ethernet transmitting hardware calculates the Ethernet CRC32 checksum and the 134 Advanced Topics receiving hardware validates this checksum If the received checksum is wrong Ethereal won t even see the packet as the Ethernet hardware internally throws away the packet
193. ties to this License 7 If as a consequence of a court judgment or allegation of patent infringement or for any other reason not limited to patent issues conditions are imposed on you whether by court order agreement or otherwise that contradict the conditions of this License they do not excuse you from the conditions of this License If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations then as a consequence you may not distribute the Program at all For example if a patent license would not permit royalty free redistribution of the Program by all those who receive copies directly or indirectly through you then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program If any portion of this section is held invalid or unenforceable under any particular circumstance the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances t is not the purpose of this section to induce you to infringe any atents or other property right claims or to contest validity of any uch claims this section has the sole purpose of protecting the ntegrity of the free software distribution system which is molemented by public license practices Many people have mad enerous contributions to the wide range of software distributed hrough that s
194. tion 8 8 The protocol specific statistics windows TCP Stream Graph See Section 8 8 The protocol specific statistics windows 50 User Interface 3 12 The Help menu The Ethereal Help menu contains the fields shown in Table 3 8 Help menu items Figure 3 10 The Help Menu test cap Ethereal DER File Edit Yiew Go Capture Analyze Statistics M CE Ax Perr PSF EE aq Manual Pages Z Eter Ethereal Online A fit Home Page Yi clear y Apply No Time Source l wiki 1 User s Guide FAQ s 4 0 726445 192 168 0 2 224 0 0 22 Downloads rship Report Example Files Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O0 0b Sd 20 cd 02 Dst Broadcast ff ff ff ff ff th Address 0 08 OO 06 04 OO 01 OO Ob o0 00 00 00 00 00 cO ag address Resolution Protocol arp 28 bytes P 120 D 120 M 0 Table 3 8 Help menu items Menu Item Accelerator Description Contents F1 This menu item brings up a basic help system Supported Pro tocols This menu item brings up a dialog box showing the supported protocols and protocol fields Manual Pages Siia This menu item starts a Web browser showing one of the locally installed html manual pages Ethereal On line gt This menu item starts a Web browser showing the chosen webpage from http www ethereal com About Ethereal This menu i
195. tion vor Selected A lt gt ANY and not Selected 4 gt ANY or not Selected 4 lt ANY ANY lt gt B ANY lt B ANY gt B Fa Copy Name resolution 8 5 3 The protocol specific Conversation List windows Before the combined window described above was available each of its pages were shown as separ ate windows Even though the combined window is much more convenient to use these separate windows are still available The main reason is they might process faster for very large capture files However as the functionality is exactly the same as in the combined window they won t be discussed in detail here 144 Statistics 8 6 The IO Graphs window User configurable graph of the captured network packets You can define up to five differently colored graphs Figure 8 5 The IO Graphs window Ethereal IO Graphs test cap 1 505 lt Graphs ITX Axis Graph 1 Color M Eiter Style Li Tick interval 0 01 sec Y Pixels per tick Color ilter Style Graph 3 Color i Filter Style Li Y Axis f Unit Packets Tick W Graph 4 Color ilter Style Scale 10 v Graph 5 Color D ilter Style The user can configure the following things e Graphs e Graph 1 5 enable the graph 1 5 only graph 1 is enabled by default e Color the color of the graph cannot be changed e Filter a display filter for this graph on
196. to find the next packet including two null bytes in the packet data e String Find a string in the packet data with various options The value to be found will by syntax checked while you type it in If the syntax check of your value succeeded the background of the entry field will turn green if it fails it will turn red 115 Working with captured packets You can choose the direction to be searched for e Up Search upwards in the packet list decreasing packet numbers Down Search downwards in the packet list increasing packet numbers 6 6 2 The Find Next command Find Next will continue searching with the same options like in the last Find Packet run 6 6 3 The Find Previous command Find Previous will do the same thing as Find Next but with reverse search direction 116 Working with captured packets 6 7 Go to a specific packet 6 7 1 6 7 2 6 7 3 6 7 4 6 7 5 6 7 6 You can easily jump to specific packets with one of the menu items in the Go menu The Go Back command Go back in the packet history works much like the page history in current web browsers The Go Forward command Go forward in the packet history works much like the page history in current web browsers The Go to Packet dialog box Figure 6 10 The Go To Packet dialog box Ethereal Go To Packet PB Packet number 123 This dialog box will let you enter a packet num
197. to look The list of Ethernet or IP endpoints is usually what you re looking for What is an Endpoint A network endpoint is the logical endpoint of separate protocol traffic of a specific protocol layer The endpoint statistics of Ethereal will take the following endpoints into account e Ethernet an Ethernet endpoint is identical to the Ethernet s MAC address e Fibre Channel XXX insert info here e FDDI a FDDI endpoint is identical to the FDDI MAC address e IPv4 an IP endpoint is identical to its IP address e IPX XXX insert info here e TCP a TCP endpoint is a combination of the IP address and the TCP port used so different TCP ports on the same IP address are different TCP endpoints e Token Ring a Token Ring endpoint is identical to the Token Ring MAC address e UDP a UDP endpoint is a combination of the IP address and the UDP port used so different UDP ports on the same IP address are different UDP endpoints 4 Broadcast multicast endpoints Broadcast multicast traffic will be shown separately as additional endpoints Of course as these endpoints are virtual endpoints the real traffic will be received by all multicast some of the listed unicast endpoints The Endpoints window This window shows statistics about the endpoints captured Figure 8 3 The Endpoints window 142 Statistics 8 4 3 Endpoints test cap Ethernet 5 TCP 11 UDP 10 Ethernet Endpoints Packets Tx Packets
198. tocol dissectors disable a protocol dissector completely or temporarily divert the way Ethereal calls the dissectors The Enabled Protocols dialog box The Enabled Protocols dialog box lets you enable or disable specific protocols all protocols are en abled by default When a protocol is disabled Ethereal stops processing a packet whenever that pro tocol is encountered Note Disabling a protocol will prevent information about higher layer protocols from being displayed For example suppose you disabled the IP protocol and selected a packet containing Ethernet IP TCP and HTTP information The Ethernet information would be displayed but the IP TCP and HTTP information would not disabling IP would prevent it and the other protocols from being displayed Figure 9 5 The Enabled Protocols dialog box 160 Customizing Ethereal Ethereal Enabled Protocols Enabled Protocols i Protocol v Description SECECECEGEGECECECEGEGECECECEGEGECECECEC 3GPP2 411 802 11 MGT 802 11 Radiotap AL AAL3 4 AARP ACAP ACN ACSE AFP AFS RX 4H AIM AIM Administration AIM Advertisements AIM BOS AIM Buddylist AIM Chat AIM ChatNaw AIM Directory 3GPP2 411 IEEE 802 11 wireless LAN management frame IEEE 802 11 Radiotap Capture header ATM AAL1 ATM 44L3 4 Appletalk Address Resolution Protocol Application Configuration Access Protocol ACN OSI ISO IEC 10035 1 ACSE Protocol AppleTalk Filing Pr
199. ts as h ex or o ctal Default is hex 1l typenum Specify link layer type number Default is 1 Ethernet See net bpf h for list of numbers Generate no output at all automatically turns off d e l3pid Prepend dummy Ethernet II header with specified L3PID in HEX Example e 0x800 i proto Prepend dummy IP header with specified IP protocol in DECIMAL Automatically prepends Ethernet header as well Example i 46 m max packet Max packet length in output default is 64000 u srcp destp Prepend dummy UDP header with specified dest and source port in DECIMAL Automatically prepends Ethernet and IP headers as well Example u 30 40 T srcp destp Prepend dummy TCP header with specified dest and source port in DECIMAL Automatically prepends Ethernet and IP headers as well Example T 50 60 s srcp dstp tag Prepend dummy SCTP header with specified dest source ports and verification tag in DECIMAL Automatically prepends Ethernet and IP headers as well Example s 30 40 34 S srcp dstp ppi Prepend dummy SCTP header with specified dest source ports and verification tag 0 It also prepends a dummy SCTP DATA chunk header with payload protocol identifier ppi Example S 30 40 34 t timefmt Treats the text before the packet as a date time code th specified argument is a format string of the sort supported by strptime Example The time 10 15 14 5476 has the format code TOH IM FSN NOTE The subsecond componen
200. tting up Ethereal to capture packets for the first time can be tricky Tip A comprehensive guide How To setup a Capture is available at ht tp wiki ethereal com CaptureSetup Here are some common pitfalls e You need to have root Administrator privileges to start a live capture e You need to choose the right network interface to capture packet data from e You need to capture at the right place in the network to see the traffic you want to see e and a lot more If you have any problems setting up your capture environment you should have a look at the guide mentioned above 63 Capturing Live Network Data 4 3 Start Capturing One of the following methods can be used to start capturing packets with Ethereal n e You can get an overview of the available local interfaces using the Z fg Capture Interfaces i dialog box see Figure 4 1 The Capture Interfaces dialog box You can start a capture from this dialog box using one of the Capture button s e You can start capturing using the 1 Capture Options dialog box e If you have selected the right capture options before you can immediately start a capture using fa Capture Start menu toolbar item The capture process will start immediately e If you already know the name of the capture interface you can start Ethereal from the command line and use the following thereal i eth0 k This will start Ethereal c
201. ur in carrying out the instructions in Ex ample 2 1 Building GTK from source If you have downloaded the source to libpcap the general instructions shown in Example 2 2 16 Building and Installing Ethereal Building and installing libpcap will assist in building it Also if your operating system does not support tcpdump you might also want to download it from the tcpdump web site and install it Example 2 2 Building and installing libpcap gzip dc libpcap 0 8 3 tar Z tar xvf lt much output removed gt cd libpcap_0_8_3 configure lt much output removed gt make lt much output removed gt make install lt much output removed gt make install incl lt much output removed gt Note The directory you should change to will depend on the version of libpcap you have downloaded In all cases tar xvf will show you the name of the directory that has been unpacked When installing the include files you might get the error shown in Example 2 3 Errors while in stalling the libpcap include files when you submit the command make install incl Example 2 3 Errors while installing the libpcap include files usr local include pcap h usr bin install c m 444 o bin g bin pcap namedb h usr local include pcap namedb h usr bin install c m 444 o bin g bin net bpf h usr local include net bpf h usr bin install cannot create regular file usr
202. using the command line See Section 9 2 Start Ethereal from the command line for details Note In the following chapters a lot of screenshots from Ethereal will be shown As Ethere al runs on many different platforms and there are different versions of the underlying GUI toolkit GTK 1 x 2 x used your screen might look different from the provided screenshots But as there are no real differences in functionality these screenshots should still be well understandable 30 User Interface 3 3 The Main window Lets look at Ethereal s user interface Figure 3 1 The Main window shows Ethereal as you would usually see it after some packets captured or loaded how to do this will be described later Figure 3 1 The Main window test cap Ethereal DAR File Edit Yiew Go Capture Analyze Statistics Help JAAA SAVANA HaT FG aq erer dP Expression Ysclear Apply AA No Time Source Destination Protocol Info 1 0 000000 192 Broadcast ARP who has 192 0 Gratuitous 4 0 726445 192 168 0 2 224 0 0 22 IGMP V3 Membership Report Frame 1 42 bytes on wire 42 bytes captured Ethernet II Src 192 168 0 2 O00 0b S5d 20 cd 02 Ost Broadcast ff ff ff ff ff fh Address Resolution Protocol request gratuitous ARP oooo ff ff ff ff ff TF 00 Ob Sd 20 cd 02 08 O6 OO 01 0010 08 OO 06 04 OO 01 00 Ob Sd 20 cd 02 cO ag 00 02 0020 00 00 00 00 00 00 cO ag 00 02 File Ds test
203. ut being unable to find some modules eg tempfile py you may want to check if PYTHONPATH is set correctly On my Linux box it is PYTHON PATH usr lib python1 5 192 Related command line tools 193 Appendix E This Document s License GPL As with the original licence and documentation distributed with Ethereal this document is covered by the GNU General Public Licence GNU GPL If you haven t read the GPL before please do so It explains all the things that you are allowed to do with this code and documentation T GNU GENERAL PUBLIC LICENSE Version 2 June 1991 Copyright C 1989 1991 Free Software Foundation Inc 59 Temple Place Suite 330 Boston MA 02111 1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed Preamble The licenses for most software are designed to take away your freedom to share and change it By contrast the GNU General Public License is intended to guarantee your freedom to share and change free software to make sure the software is free for all its users This General Public License applies to most of the Free Software Foundation s software and to any other program whose authors commit to using it Some other Free Software Foundation software is covered by the GNU Library General Public License instead You can apply it to your programs too When we speak of fre
204. ve see Section 8 5 3 The protocol specific Conversa tion List windows Endpoint List Display a list of endpoints obsoleted by the combined window of End points above see Section 8 4 3 The protocol specific Endpoint List windows Service Re sponse Time Display the time between a request and the corresponding response see Section 8 7 Service Response Time ANSI See Section 8 8 The protocol specific statistics windows GSM See Section 8 8 The protocol specific statistics windows H 225 See Section 8 8 The protocol specific statistics windows ISUP Message Types See Section 8 8 The protocol specific statistics windows MTP3 See Section 8 8 The protocol specific statistics windows RTP See Section 8 8 The protocol specific statistics windows SCTP See Section 8 8 The protocol specific statistics windows SIP See Section 8 8 The protocol specific statistics windows VoIP Calls See Section 8 8 The protocol specific statistics windows WAP WSP See Section 8 8 The protocol specific statistics windows BOOTP DHCP See Section 8 8 The protocol specific statistics windows HTTP HTTP request response statistics see Section 8 8 The protocol specific statistics windows ISUP Messages See Section 8 8 The protocol specific statistics windows ONC RPC Pro grams See Sec
205. work packet size or is stream based like TCP which doesn t know data chunks at all In that case the network protocol has to handle that chunk boundaries itself and if required spread ing the data over multiple packets It obviously also needs a mechanism to find back the chunk boundaries on the receiving side Tip Ethereal calls this mechanism reassembling although a specific protocol specification might use a different term for this e g desegmentation defragmentation How Ethereal handles it For some of the network protocols Ethereal knows of a mechanism is implemented to find decode and display these chunks of data Ethereal will try to find the corresponding packets of this chunk and will show the combined data as additional pages in the Packet Bytes pane for information about this pane see Section 3 17 The Packet Bytes pane Figure 7 2 The Packet Bytes pane with a reassembled tab 0000 08 00 06 ab 04 53 08 00 O6 6b 7f bd 08 OO 45 00 esoosSee aKeaeeks a 0010 01 48 33 c7 00 OO 1e 11 dd 51 be aS 08 Oa be as sH3 eeee e Qes 0020 09 32 41 af OF 04 01 34 OO b4 04 OO 2e OO 10 00 0 Aa net sssssoose 0030 OO OO 00 OO a0 de 97 Gc di 11 82 71 00 57 80 fO_ l g W v Frame 342 bytes Reassembled DCE RPC 1604 bytes Note Reassembling might take place at several protocol layers so it s possible that multiple tabs in the Packet Bytes pane appear Note You will find the reassem
206. xcept as expressly provided under this License otherwise to copy modify sublicense or distribu void and will automatically terminate your right However parties who have received copies or rig this License will not have their licenses termina parties remain in full compliance 5 You are not required signed it However nothi distribute the Program or its derivative works prohibited by law if you do not accept this Licen to accept this License ring equivalent e counts as d parties are not t code tribute the Program Any attempt te the Program is s under this License hts from you under ted so long as such since you have not ng else grants you permission to modify or These actions are modifying or distributing the Program or any wor Program you indicate your acceptance of this Li all its terms and conditions for copying distrib s Therefore by k based on the cense to do so and uting or modifying the Program or works based on it 6 Each time you redistribute the Program Program the recipient au original licensor to copy tomatically receives a or any work based on the license from the distribute or modify the Program subject to 196 This Document s License GPL these terms and conditions You may not impose any further restrictions on the recipients exercise of the rights granted herein You are not responsible for enforcing compliance by third par
207. yed button is set only the currently displayed packets are taken into account to the selected rule e All packets will process all packets e Selected packet only process only the selected packet e Marked packets only process only the marked packets e From first to last marked packet process the packets from the first to the last marked one e Specify a packet range process a user specified range of packets e g specifying 5 10 15 20 will process the packet number five the packets from packet number ten to fifteen inclusive and every packet from number twenty to the end of the capture 96 File Input Output and Printing 5 9 The Packet Format frame The packet format frame is a part of various output related dialog boxes It provides options to select which parts of a packet should be used for the output function Figure 5 12 The Packet Format frame Packet Format Packet summary line Packet details All collapsed As displayed All expanded Packet bytes Each packet on a new page e Packet summary line enable the output of the summary line just as in the Packet List pane e Packet details enable the output of the packet details tree e All collapsed the info from the Packet Details pane in all collapsed state e As displayed the info from the Packet Details pane in the current state e All expanded the info from the Packet Details pane in all expanded state e Packet by
208. you can do now except to re peat the whole capture process again with a higher or no packet size limitation 174 Ethereal Messages C 2 Packet Details Messages These messages might appear in the packet details C 2 1 Response in frame 123 The current packet is the request of a detected request response pair You can directly jump to the corresponding response packet just by double clicking on this message C 2 2 Request in frame 123 Same as Response in frame 123 above but the other way round C 2 3 Time from request 0 123 seconds The time between the request and the response packets 175 Ethereal Messages 176 Appendix D Related command line tools D 1 Introduction Beside the Ethereal GUI application there are some command line tools which can be helpful for doing some more specialized things These tools will be described in this chapter 177 Related command line tools D 2 tcpdump Capturing with tcpdump for viewing with Ethereal There are occasions when you want to capture packets using tcpdump rather than ethereal espe cially when you want to do a remote capture and do not want the network load associated with run ning Ethereal remotely not to mention all the X traffic polluting your capture However the default tepdump parameters result in a capture file where each packet is truncated because tcpdump by default does only capture the first 68 bytes o
209. your bug report Note If you do not have gdb available you will have to check out your operating system s debugger You should mail the traceback to the ethereal dev AT lethereal com mailing list 1 7 7 Reporting Crashes on Windows platforms The Windows distributions don t contain the symbol files pdb because they are very large For this reason it s not possible to create a meaningful backtrace file from it You should report your crash just like other problems using the mechanism described above Introduction Chapter 2 Building and Installing Ethereal 2 1 Introduction As with all things there must be a beginning and so it is with Ethereal To use Ethereal you must e Obtain a binary package for your operating system or e Obtain the source and build Ethereal for your operating system Currently only two or three Linux distributions ship Ethereal and they are commonly shipping an out of date version No other versions of UNIX ship Ethereal so far and Microsoft does not ship it with any version of Windows For that reason you will need to know where to get the latest version of Ethereal and how to install it This chapter shows you how to obtain source and binary packages and how to build Ethereal from source should you choose to do so The following are the general steps you would use 1 Download the relevant package for your needs e g source or binary distribution 2 Build the source into
210. ystem in reliance on consistent application of that ystem it is up to the author donor to decide if he or she is willing o distribute software through any other system and a licensee cannot mpose that choice Bet tA HHUH This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License 8 If the distribution and or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces th original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries so that distribution is permitted only in or among countries not thus excluded In such case this License incorporates the limitation as if written in the body of this License 9 The Free Software Foundation may publish revised and or new versions of the General Public License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns Each version is given a distinguishing version number If t he Program specifies a version number of this License which applies to i n t and any d conditions later version you have the option of following the terms a O either of that version or of any later version published by the Free Software Foundation If the Program does not specify a vers

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