Red Hat Server Tux 2.1 User's Manual
Contents
1. Note The http_subdocroot and ftp_subdocroot are relative to DOCROOT echo www gt proc sys net tux http subdocroot echo ftproot proc sys net tux ftp subdocroot Restart TUX to apply the changes service tux restart After executing these commands the TUX FTP server will be running on port 21 To have it display directory listings run the generatetuxlist script from the FTP docroot This script creates the files TUx LIST and TUX NLIST files that cache the directory list ing Everytime the FTP docroot directory changes the script must be re run to generate an updated directory listing B Note The TUX FTP server has been through numerous stresstests and FTP client compatibility tests However it is still early software TUX FTP has no known bugs or security holes at the moment It has not been tested with a wide number of FTP clients yet only the most obvious ones 22 Chapter 3 Configuration 3 9 1 TUX FTP Server Security Features The following are security features of the TUX FTP Server Because TUX does not start per client processes the memory allocation overhead for each FTP client logged in is less than 10 KB This allows thousands of parallel connections Paranoid parser and paranoid command evaluation Chroots to docroot Never starts any external userspace process All FTP functionality is done in a approxi mately 900 lines C module in the kernel Even in kernel mode the TUX FTP Server dro2. Table 3 1 TUX Configuration Parameters Name Defaut Description serverport No longer available To change the TUX HTTP server port use the command echo http 0 0 0 0 80 gt proc net tux 0 listen 0 where 80 is the port number clientport 8080 The port listened to by the userspace http daemon documentroot var www html The directory where the web pages are stored If using the init script etc rc d init d tux documentroot should be set in etc sysconfig tux as DOCROOT Chapter 3 Configuration 13 Name Default Description http_subdocroot No value set by default The directory relative to the documentroot where the web pages are stored TUX defaults to using documentroot if http_subdocroot has no value ftp_subdocroot No value set by default The directory relative to the documentroot where the files to be served by the FTP server are stored TUX defaults to using the document root defined for the HTTP server if ftp_subdocroot has no value ftp log retr only If set to 0 TUX will log every other command as well If set to 1 TUX will only log RETR FIP commands to cut down the log size ftp wait close 1 If set to 1 TUX will wait for data socket to close before sending completion message to command socket Certain clients for example lynx get confused by TUX s high level of asynchronity This setting slows down FTP RETR downloads and directory listings and increases packet count but it works
3. A similar operation is already performed by the Network File System NFS daemon that runs in the kernel TUX also has the ability to cache dynamic content TUX modules which can be build in kernel space or in user space user space is recommended can create objects which are stored using the page cache To respond to a request for dynamic data a TUX module can send a mix of dynamically generated data and cached pre generated objects taking maximal advantage of TUX s zero copy architecture This new architecture for serving dynamic content requires a new API The current API s for CGI can not be sufficiently mapped to TUX s API Thus existing CGI applications must be converted before TUX will process them If the CGI application does not require the in creased speed of TUX TUX can process it by running the CGI application normally This is done through TUX s CGI module TUX can also handle a complex request CGI or oth erwise by redirecting it to another web server daemon such as Apache In other words static content TUX modules old style CGI applications and programs specifically written for other webservers can be run on the same system with TUX as the main web server In summary the differences between TUX and other webservers as well as the benefits of using TUX include TUX runs partly within a custom version of kernel 2 4 x or higher and partly as a user space daemon With a capable network card TUX enables direc
4. around broken FTP clients If set to 0 TUX will not wait for the FTP client to notice the closed data socket 404 page 404 html If TUX does not manage to look up a requested page then it first tries to look up the document specified in 404 page If the 404 page can not be found the canned 404 message is sent The file is relative to the document root threads The number or The number of kernel threads and server threads set at associated daemon threads to be used most to 1 per CPU Can not be greater than the number of CPUs on the system If using the init script etc rc d init d tux threads should be set in etc sysconfig tux as TUXTHREADS mode allowed S IROTH Required permissions for files TUX will process See man 2 stat for all values mode forbidden dir sticky execute Files with this permission mask are forbidden and will not be processed by TUX See man 2 stat for all values nonagle If set to 0 standard Nagle output packet merging If set to 1 no Nagle merging of output packets If set to 2 TCP_CORK style output packet merging 14 Chapter 3 Configuration Name Default Description push_all cgi_cpu_mask cgi_inherit_cpu var www tux cgiroot The directory in which TUX runs CGI Oxffffffff If set to 0 may merge subsequent packets If set to 1 force a packet boundary right after the end of the TUX request Tf set to 0 it is disabled If set to 1 sending gzip compressed data is
5. log files use the command usr sbin tux2w3c var log tux The tux2w3c program converts the 10 Chapter 2 Installation binary log files into into standard W3C conforming HTTPD log files If you want to save the ASCII output you can redirect the output to a file usr sbin tux2w3c var log tux gt tux log where tux log is the name of the output file Sample log file output 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 255 255 255 255 Fri Nov 0 404 95 4 1253 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 4084 200 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 61 200 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 200 95 4 12 3 Fri Nov 9 0 95 4 12 3 Fri Nov 9 0 200 95 4 12 3 Fri Nov 9 0 95 4 1243 Fri Nov 9 0 8523 200 95 4 32 3 Fri Nov 9 0 34531 200 06 06 06 06 06 06 06 06 06 06 06 06 06 06 10 04 22 04 22 04 22 04 26 04 35 04 37 41 05 56 200 06 10 200 9 01 06 10 200 200 200 200 200 200 200 200 200 200 200 200 200 200 GET GET 2001 GET GET GET GET GET GET GET GET GET GET GET GET GET GET test html HTTP 1 1 53 200 HTTP 1 1 2890 200 GET icons apache pb gif HTTP 1 1 poweredby png HTTP 1 1 1154 200 test html HTTP 1 1 53
6. number of user space HTTP modules and they can be compiled in a language of choice They have full address space protection can not crash the kernel and are unpriviledged A list of user space loadable TUX modules and their location must be specified with the TUXMODULES parameter in etc sysconfig tux Refer to Section 3 3 for details Starting with TUX version 2 0 13 and kernel patch 2 4 2 P3 user space loadable modules do not require special permissions to be activated Instead the module is specified using a common MIME type definition file The user space modules must end with the file extension tux or x and specified with the TUXMODULES parameter in etc sysconfig tux The file must be owned by root with root as the group and must be world readable It does not have to be executable For example to use the demo tux user space loadable module you might have the following file root m ls 1 var www html demo tux rw rw r 1 root root 0 Sep 3 04 42 var www html demo tux If TUX finds a URL object that has this MIME type it searches the internal list of modules de fined as TUXMODULES in etc sysconfig tux If there is a match TUX sends the request to the user space loadable module For further information about writing a TUX user space loadable module see the file usr share doc tux lt version gt TUXAPI user txt 25 26 Chapter 5 User space Loadable Modules Index Symbols etc rc d init d tux start 18
7. should not be set in etc sysctl conf because the init script will override parameters set in etc sysctl conf Using the init script is the preferred method for starting TUX Table 3 2 etc sysconfig tux parameters Parameter Defaut Descriptin TUXTHREADS The number of The number of kernel threads and associated server threads daemon threads to be used cannot be greater set at most to 1 than the number of CPUs on the system per CPU Chapter 3 Configuration 17 Parameter Defaut Description DOCROOT var www html The document root the directory where the web pages are stored CGI UID UID user as which to run CGI programs CGI_GID GID group as which to run CGI programs DAEMON_UID UID user as which the daemon runs DAEMON_GID GID group as which the daemon runs CGIROOT var www html The directory where the CGI programs are stored CGI programs can be started in the chroot environment by default Set CGIROOT if you want CGI programs to have access to the whole system MAX_KEEPALIVH 3IMEOUT Timeout value for each HTTP connection Use this to prevent connection hangs TUXMODULES demo tux list of user space loadable TUX modules see man demo2 tux 2 tux for more information demo3 tux demo4 tux MODULEPATH Path to the user space loadable TUX modules 3 3 3 proc net tux Parameters After starting TUX the proc net tux directory contains the file stat This file contains stati
8. 200 manual index html HTTP 1 1 5557 200 test html HTTP 1 1 53 200 manual images apache header gif HTTP 1 1 test html HTTP 1 1 53 200 manual images pixel gif HTTP 1 1 test html HTTP 1 1 53 200 manual invoking html HTTP 1 1 test html HTTP 1 1 53 200 manual stopping html HTTP 1 1 test html HTTP 1 1 53 200 manual howto ssi html HTTP 1 1 manual new features 1 3 html HTTP 1 1 Chapter 3 Configuration This chapter describes how to configure the TUX Web Server 3 1 Modes of Operation The recommended mode of operation is to have TUX running as the main web server and Apache run as the assistant Client Port 8080 or other Web Server Port 80 For the recommend mode where TUX is the main web server the configuration for the user space daemon must be changed to use port 8080 For Apache configuration the changes are made in the configuration file etc httpd conf httpd conf by changing the line Port 80 to Port 8080 For security reasons the line BindAddress should be changed to BindAddress 127 0 0 1 This will prevent outside users from accessing Apache directly You must restart Apache for the changes to take effect with the command etc rc d init d httpd restart The alternate mode of operation is to have the user space daemon such as Apache as the main web server and TUX as the assistant Client Port 80 Web Server Port 8080 or other 3 2 Compressed Gzip Data S
9. If set to 0 referer logging is disabled max_backlog 2048 Maximum size of SYN backlog of the TUX listening socket 16 Chapter 3 Configuration Name Default Description virtual_server Turns on mass virtual hosting Hosts are headers from the browser that are directly turned into DOCROOT Host virtual docroots This way any number of hosts can be served by a single TUX server without any performance penalty at all Refer to Section 3 8 for details mass hosting hash If virtual server is enabled this parameter modifies the hostname mapping to be more effective for a large number of hosts Refer to Section 3 8 for details strip host tail If virtual server is enabled this parameter strips off hostname components Refer to Section 3 8 for details Zerocopy parse Use the input packet buffer as a temporary buffer and avoids copying input data defer accept 0 disabled if If set to 1 then TUX processes will not keepalive_timeout or be woken up on the initial SYN ACK max_keepalives is set event of anew TCP connection but only after the first real data packet has arrived If set to 0 this feature is disabled http_dir_indexing 0 disabled Tf set to 1 TUX will list files in readable directories if an index file does not exist 3 3 2 Init Script Parameters If the TUX init script etc rc d init d tux is used the following parameters can be set in the file etc sysconfig tux see Table 3 2 They
10. OOT cgi bin directory or the directory specified by the cgiroot parameter Refer to Section 3 3 for details Refer to Chapter 5 for details about the TUX module MIME type 3 8 Mass Virtual Hosting TUX supports mass virtual hosting which enables a very high number of virtual hosts There are three tunables that deal with virtual hosting e virtual server Valid values are 0 1 2 or 3 mass hosting hash Valid values are 0 1 2 or 3 e strip host tail Value must be an integer 20 Chapter 3 Configuration These three tunables depend on each other and the strip_host_tail tunable is only used if host based virtual serving is enabled Otherwise it is ignored 3 8 1 virtual_server If the value is set to 0 virtual hosting is disabled http www example com a html gt DOCROOT a html If the value is set to 1 host based virtual hosting is enabled http www some site com a html gt DOCROOT some site com a html cg Note TUX strips off the www prefix variants and transforms the hostname to lowercase If the value is set to 2 IP based virtual hosting is enabled http www some site com a html gt DOCROOT 1 2 3 4 a html If the value is set to 3 a mixture of host based and IP based virtual hosting is enabled http www some site com a html gt docroot 1 2 3 4 some site com a html 3 8 2 mass_hosting_hash The mass_hosting_hash tunable modifies the hostname mapping to be more effective for a la
11. TUX 2 1 Reference Manual Red Hat Inc TUX 2 1 Reference Manual Copyright O 2001 by Red Hat Inc TUX EN 2 1 RHI 2001 12 02T23 45 0400 Red Hatis a registered trademark and the Red Hat Shadow Man logo RPM the RPM logo and Glint are trademarks of Red Hat Inc Linux is a registered trademark of Linus Torvalds All other trademarks and copyrights referred to are the property of their respective owners Copyright 2001 by Red Hat Inc Permission is granted to copy distribute and or modify this document under the terms of the GNU Free Documentation License Version 1 1 or any later version published by the Free Software Foundation A copy of the license is available at http www gnu org copyleft fdl html Distribution of substantively modified versions of this document is prohibited without the explicit permission of the copyright holder Distribution of the work or derivative of the work in any standard paper book form for commercial purposes is prohibited unless prior permission is obtained from the copyright holder Table of Contents De Whatis TUX nrc 7 1 1 New LUX 2 1 Feature Suae neta itn ee ge leen e eee n ndn na 1 2 Summary of System Requirements 1 21 Current Limitations 25a dios 2 Installation 5e Eu Kissen 9 2 1 Installation Instructions sees tentent nennen 9 2 1 1 L08 RN 9 3 Configuration scsessessessesseseesseessensesesnesnesesncenssseceenssnesseseesesnesucase
12. aceneseseeasenesneaesnesnesncsseneeneaneses 3 1 Modes of Operatii soye oeer eE tette nennen treten tenens 3 2 Compressed Gzip Data Stream M 3 3 Datammetets is nates A ANN 3 3 1 proc sys net tux Parameters sese nennen 12 3 3 2 Init Script Parameters 3 3 3 proc net tux Parameters e 3 3 4 Required Parameters sse 94 Starting TUX c oen Re ente ene dte Me Sr eae e Mee t ef PM 3 4 1 IRO Affinity 4 3 5 Stopping TUX 3 6 Debugging TUX 3 7 MIME Types 3 8 Mass Virtual Hosting 3 8 1 virtual server 3 8 2 mass hosting hash 3 8 3 string host tail 3 9 TUX as an FTP Server j 5 User space Loadable Modules Chapter 1 What is TUX TUX is a kernel based web server licensed under the GNU General Public License GPL It is currently limited to serving static web pages and coordinating with kernel space mod ules user space modules and regular user space web server daemons to provide dynamic content Regular user space web servers do not need to be altered in any way for TUX to coordinate with them However user space code has to use a new interface based on the tux 2 system call Although dynamic content is becoming increasingly popular there is still a need to serve static content For example nearly all images are static TUX can serve static content very efficiently from within the Linux kernel
13. etc rc d init d tux stop 19 etc sysconfig tux 16 etc sysctl conf 11 proc sys net tux 12 var log tux 9 B Benefits 7 C Client Port 11 Compressed Data 11 compression 11 Configuration 11 Current Limitations 8 D Debugging TUX 19 Dynamic Content 7 F FIP Server 21 Directory Listings 21 Document Root 21 G gettuxconfig 19 Gzip 11 init script parameters 16 Installation 9 Installation Instructions 9 IRQ Affinity 18 L Limitations 8 Log Files 9 MIME Types 19 Modes 11 Modules User loadable Modules 25 P Parameters 12 List of Parameters 12 Required Parameters 17 Permissions 23 Port 11 S Scripts 17 Security 23 Server Port 11 Starting TUX 18 Static Content 7 Stopping TUX 19 sysctl 23 System Requirements 8 T TUX 2 1 enhancements 8 tux mime types 19 tux2w3c 9 V virtual hosting 19 Ww What is TUX 7 27
14. ill time out if a request does not arrive within a pre specified time Timeout value is set in seconds max_object_size 100MB Maximum file size TUX is willing to serve Dprintk If TUX_DEBUG is turned on then print out very verbose messages to syslog Should only be used for debugging purposes ack_pingpong 1 Delay TCP ACK for incoming frames in the hopes of a subsequent output frame Separate ACK will happen nevertheless if no output frame is generated within a timeout all_userspace If set to 1 every complete and valid HTTP request will be bounced to the first user space module The user space module takes control over the entire URL space Then the user space module can make a decision to 1 serve a static reply 2 serve a cached dynamic reply or 3 create a dynamic reply If set to 0 all_userspace is disabled application_protocol If set to 1 it enables the TUX FTP server If set to 0 this feature is disabled Refer to Section 3 9 for details logentry_align_order Currently unused logfile var log tux The filename of the TUX binary logfile Refer to Section 2 1 1 for more information logging If set to 1 logging is enabled If set to 0 logging is disabled redirect_logging Set to 0 to suppress redirected connections Can be changed at runtime and takes effect immediately referer_logging Tf set to 1 referer logging is enabled and will be automatically printed by tux2w3c if the referer entry is present
15. it d tux start script stop TUX by executing the etc rc d init d tux stop script This will unload all user space TUX modules au tomatically If you did not use the scripts provided stop TUX with the command usr sbin tux s Or usr sbin tux stop 3 6 Debugging TUX To print out the state and various other information about TUX execute the gettuxconfig script You must be root to run this script The checkbindings shell script checks an existing TUX SMP configuration whether all IRQ interface and listening socket bindings and affinities are set up correctly It assumes that the interfaces eth0 eth1 eth2 and so on are used linearly and mapped linearly The script warns if it finds any inefficiency 3 7 MIME Types TUX supports three types of MIME types starting with version 2 0 13 and kernel patch 2 4 2 P3 They are defined in etc tux mime types Table 3 4 MIME Types MIME Type File Description Extension TUX redirect pl php All extensions listed after TUX redirect will be redirected to the secondary server TUX CGI cgi pl All extensions listed after TUX CGI will be handled by the TUX CGI engine directly TUX module tux x All extensions listed after TUX module will be handled by TUX userspace modules The TUX redirect MIME type will redirect all requests to files ending in p1 or php to Apache without having to check for file permissions The rux cG1 MIME type specify scripts that should be located in the DOCR
16. odule support Mass virtual hosting support The host based virtual server patch has been added to TUX There is no limit on the number of virtual hosts supported only RAM and diskspace e CGlIs can be bound to particular CPUs or can be left unbound A number of bugs were fixed which caused performance problems TUX 2 1 is now significantly faster than TUX 1 0 1 2 Summary of System Requirements TUX Customized 2 4 x based version of the kernel or higher x86 Alpha IA64 or PowerPC 64 platform should work on PowerPC 32 untested on Sparc Alternate web server such as Apache running on the same server to process unknown requests 1 2 1 Current Limitations TUX can only call the other Web server such as Apache on the same server In future revisions it will allow the rollover of unsupported content to an alternate server Chapter 2 Installation This chapter describes how to install TUX 2 1 Installation Instructions 1 For optimal performance create a separate RAID partition as the document root for TUX 2 Configure and install the kernel with TUX support built in if it has not already been provided with TUX configured 3 Install the TUX package with the command rpm Uvh tux 2 1 0 2 1386 rpm mod ify as necessary for new versions 4 Create an index html file in var www htm1 the default document root directory 5 Start TUX with the command service tux start or tux init start on Linux
17. ps all priviledges and switches to uid and group nobody Only the most trivial globbing mget supported and no recursion support Chapter 4 Security TUX is designed to have very strict security This is possible because the assistant user space daemons is used to handle the complex exceptions TUX only serves a file if 1 The URL does not contain 2 The URL does not start with 3 The URL points to a file that exists 4 The file is world readable 5 The file is not a directory 6 The file is not executable 7 The file does not have the sticky bit set 8 The URL does not contain any forbidden substrings such as Configurable through the sysctl parameters in proc sys net tux Configurable through the sysctl parameters in proc sys net tux Configurable through the sysctl parameters in proc sys net tux Configurable through the sysctl parameters in proc sys net tux Configurable through the sysctl parameters in proc sys net tux PRP 23 24 Chapter 4 Security Chapter 5 User space Loadable Modules In addition to parts of TUX running in kernel space user loadable modules can also be writ ten for TUX The API for the user loadable modules is currently under development This section of the docu mentation will be updated as the API becomes available User space loadable modules are usually a single c file and are compiled as a shared li braries as a so file There can be an unlimited
18. recommended you try the following 3 4 1 IRQ Affinity Binding IRQ s to a group of CPU s is a new feature of the 2 4 kernel While it was originally developed as part of TUX it is now a generic and independent kernel feature Every IRQ source in Linux has an entry in proc irq directory For example the settings for IRQ 40 is stored in proc irq 40 IRQ affinity or IRQ bindings is configured though the smp_affinity setting in that directory For example the smp_affinity for IRQ 40 is in proc irg 40 smp_affinity The value of the smp_affinity setting is a bitmask of all CPU s that are permitted as a resource for the given IRQ The default value for smp_affinity is the HEX value ox tffff This means the processes for the IRQ are sent to all CPU s You are not allowed to turn off all CPU s for an IRQ If the IRQ controller does not support IRQ affinity the value can not be changed from the default If multiple CPU s are defined then the IRQ source uses the least busy CPU This is called lowest priority APIC routing IRQ affinity is achieved by binding an IRQ to a specific CPU or group of CPU s by echoing a HEX value to smp_affinity for the IRQ Thus TUX thread N is bound to CPU N If a single TUX thread is used which is recom mended and there is only one network interface card then the network interface card s IRQ should be bound to CPUO Chapter 3 Configuration 19 3 5 Stopping TUX If TUX was started with the etc rc d in
19. rge number of hosts If the value is set to 0 mass_hosting_hash is disabled Tf the value is set to 1 http www some site com a html gt docroot s some site com a html Tf the value is set to 2 http www some site com a html gt docroot s so some site com a html Tf the value is set to 3 http www some site com a html gt docroot s so som some site com a html 3 8 3 string host tail The strip host tail tunable strips off hostname components starting at the end of the hostname If the value is set to 0 this tunable is disabled If the value is set to 1 Chapter 3 Configuration 21 http www some site com a html gt docroot some site a html Tf the value is set to 2 http www some site com a html gt docroot site a html and so on 3 9 TUX as an FTP Server Starting with version 2 0 21 of TUX and version 2 4 2 U7 of the TUX patched kernel TUX can be configured to run as an anonymous FTP server To use TUX as an HTTP and FTP server at the same time use the following commands echo http 0 0 0 0 80 gt proc net tux 0 listen 0 echo ftp 0 0 0 0 21 gt proc net tux 0 listen 1 By default the document root for the FTP server is the document root for the HTTP server set aS DOCROOT in etc sysconfig tux or the value of proc sys net tux document root To configure different document roots for the HTTP and FTP server set the DOCROOT in etc sysconfig tux and execute the following commands
20. stics on every allocated request structure As this works even if TUX DEBUG is turned off this should help debugging things a bit more It can also be used to calculate file download status For example TUX FTP the 100 f pos filelen gives the current progress of down load Itis possible to bind the logger thread to any particular CPU or group of CPUs so you can localize IO via proc net tux 10og cpu mask The default is to run on any CPU 3 3 4 Required Parameters Before starting TUX the following parameters must be set serverport clientport DOCROOT The DOCROOT for TUX must be the same document root directory as Apache or other user space daemon running as the assistant web server for TUX to properly redirect requests 18 Chapter 3 Configuration 3 4 Starting TUX TUX can be started by issuing the command etc rc d init d tux start This script is written to start TUX on a single processor as well as a multi processor server If you choose to write your own script to start TUX or start it from the usr sbin tux binary you can use the following options Table 3 3 usr sbin tux options Option Description i O run in the background as a daemon D date interval seconds how often in seconds to update the date string the default is 1 second show help message display brief usage message affinity is a small performance boost If you are not experiencing any performance difficulties it is not
21. systems not running Red Hat Linux and test the URL http localhost with lynx or any Web browser The latest TUX releases can be downloaded from http people redhat com mingo TUX patches To install a TUX patch use the following instructions 1 Download the latest TUX patch and userspace utilities from http people redhat com mingo TUX patches 2 Apply the TUX patch to a vanilla 2 4 2 kernel tree with the command patch p0 tux2 full 2 4 2 X6 where tux2 full 2 4 2 X6 is the TUX kernel patch 3 Usemake oldconfig to enable TUX in the kernel config compile it and boot into the TUX kernel 4 Compile and install the userspace utilities where tux 2 0 25 is the version of TUX you want to install tar xzvf tux 2 0 25 tar gz cd tux 2 0 25 make make install 5 Create an index html file in var www htm1 the default document root directory 6 Start TUX with the command service tux start or tux init start on Linux systems not running Red Hat Linux and test the URL http localhost with lynx or any Web browser 2 1 1 Log Files For each request TUX logs the address of the requestor a date and time stamp accurate to at least one second specification of the file requested size of the file transferred and the final status of the request The log files for TUX are stored in var 1og tuxin binary format In this binary format the log files are approximately 50 smaller than standard ASCII text log files To view
22. t scatter gather DMA from the page cache directly to the network thus avoiding data copies Whenever TUX is unsure how to process a request or receives a request it is unable to handle it always redirects the request to the user space web server daemon to handle it in an RFC compliant manner An example of this user space web server daemon is Apache Apache is used throughout this document as the user space web server daemon for readability For questions or comments about TUX or this documentation join the lt tux list redhat com gt mailing list For instructions on joining the mailing list see http www redhat com mailing lists Also visit the Red Hat TUX Web Server Support page http www redhat com services techsupport application tux html 8 Chapter 1 What is TUX 1 1 New TUX 2 1 Features The TUX 2 1 release is an incremental upgrade to TUX 1 0 and keeps source code level com patibility with user space modules The incremental enhancements include True zero copy disk reads Whereas TUX 1 0 copied files into a temporary buffer TUX 2 1 is integrated with the page cache and thus uses zero copy block IO Generic zero copy network writes TUX 2 1 uses the generic zero copy TCP framework Zero copy parsing Where possible TUX parses input packets directly Even in RAM limited situations TUX now does full back to back zero copy I O Other changes include Enhanced user space utilities and m
23. tream TUX is now able to send compressed gzip data This has the potential to decrease the amount of data the Web server sends to the client browser and decrease the browser s load time By default this data compression is disabled To enable it add the following line to etc sysctl conf net tux compression 1 The Gzip file with the extension gz must be in the same directory as the uncompressed versions of the pages you wish to serve All of the following conditions must be true for TUX to send the gz file Otherwise the original file s are sent 11 12 Chapter 3 Configuration The TUX compression feature is on in etc sysctl conf The client has explicitly stated to support gzip encoding The original file exists is a regular file and has the proper permissions The gz file exists is a regular file and has the proper permissions The gz file is newer than or has the same date as the original file The size of the gz file is smaller than original file y A cron job can be created to generate a new gzip file from the latest uncompressed data in each directory 3 3 Parameters This chapter describes how to configure TUX via the available TUX parameters u Most parameters can only be set when TUX is not active 3 3 1 proc sys net tux Parameters The following parameters are set through proc sys net tux Note this has changed from the original location of proc sys net httpand proc net http
24. turned on See Section 3 2 for details UID as which to run CGI programs Set by default to the ID for nobody in the tux init script GID as which to run CGI programs Set by default to the ID for nobody in the tux init script programs Set by default to DOCROOT in the tux init script The default value allows CGI scripts to execute on all CPUs This value can be set to bind newly started CGI scripts to a single CPU or a set of CPUs The CPUs are represented in a 32 bit bitmask where bit 1 is CPU 0 bit 2 is CPU 1 etc This value has not effect on single processor systems If set to 1 all newly started CGI scripts inherit the CPU binding of the CGl starting TUX thread all processes started by the CGI script will be bound to the same CPU as the parent CGI max_connect 1000 Maximum number of concurrent connections 3000 Maximum header size in bytes max_header_len max_output_bandwidt max_keepalive 1000 Maximum output bandwidth per connection used up by keepalive requests in bytes sec The default value of 0 means off or unlimited bandwidth Can be as low as 1 byte sec This parameter replaces max_keepalive_bw Maximum number of open keepalive connections After having reached max_keepalives connections TUX zaps old connections based on LRU Chapter 3 Configuration 15 Name Default Description keepalive_timeout Unfinished and should not be used A per client connection timer that w
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