NETServer - Black Box
Contents
1. in or dial up routing sessions with remote networks Implement four basic applications with the NETServer Technically Speaking ji NETServer allows you to implement four basic applications IP Terminal Service IP modem sharing IP IPX Network Dial In and IP IPX LAN to LAN routing Everything else it does is based on one of these four IP Terminal Service Remote terminals can log into an IP host on the NETServer s local network as if they were physically connected to it To do this the NETServer receives TTY terminal output keystrokes over a dialup line It then forwards the terminal output to the host using a virtual terminal protocol login service like Telnet or Rlogin Since the connection is bi directional the terminal also receives the host s responses Implement IP Terminal Service TTY Terminal data Terminal Telnet Rlogin PortMux NetData IP Modem Sharing Hosts on a local IP network can use a chassis modem to dial out Moreover the NETServer can create pools of modems that can be used by local hosts on a first come first served basis To do this the NETServer allows the host to establish a virtual terminal session with the modem The host can then interact with the modem s command line and from there dial out On a UNIX host you can install a pseudo TTY driver that allows the ho2. the NETServer has to do in these situations is send the packet out the right port However when there is no existing connection the NETServer has to do a bit more work The Location table contains a list of remote gateways that the NETServer can dial into When the NETServer does not have a connection to the packet s next hop it looks up the address of the gateway in the Location table The Location Table should contain a dial script that tells the NETServer how to contact the remote location Dial Scripts are most useful for on demand routing sessions In these situations the NETServer connects to a remote gateway only when it has packets queued for that location vy PAP CHAP Authentication T NETServer supports auto detecting the PAP and CHAP methods of login authentication on PPP connections If a user dials in and starts sending PPP packets the NETServer asks that the user log in with PAP enter a user name and password If the user refuses PAP authentication the NETServer demands CHAP authentication If this is also refused the NETServer hangs up PAP Password Authentication Protocol PAP is simply a fancy way of saying that the dialing user or system will respond to the User Name and Password prompts given by the authenticating system Although the NETServer will not initiate dial out PAP authentication you can accomplish the same effect by creating a dial script containing the expected pr
3. BA A Specifications Standards Supported TCP IP RIP SLIP CSLIP ICMP UDP ARP Telnet PPP RFC 1331 1332 and 1334 for PPP backward compatible with RFC 1171 and 1172 Interface Ethernet 10 Mbps Connectors 1 BNC 3 RJ 45 8 RJ 11 Power 100 250 VAC 60 50 Hz 1 5 A Size 3 5 H x 17 5 W x 12 6 D 8 9 x 44 5 x 32 cm Ordering Information This information will help you place your order quickly PRODUCT NAME NETServer 8 Port I modem 16 Port l modem v The complete package What you get when you order the NETServer e NETServer e 1 Power cord e 1 Console cable e 8 Phone cords e User s Manual ORDER CODE LRA108V LRA116V LRA108V ISDN LRA116V ISDN lt gt BLACK BOX Copyright 1996 oom rights reserved Black Box Corporation T h e S 0 u r Cc e for Connectivity NETServer 7 j oO Be nar P y ante Li LAP siaus ci a From The NETServer and NETServer I modem let you gain remote access via dialup analog or digital lines Key Features gt Access email download files access the internet and intranet and interfaced with a corporate host gt Software downloadable flash ROM gt A solid per user firewall guarantees security gt Supports Windows 95 P Share ports among users p gt T models combine ISDN and modem technology in the same device Overview Now you can gain rem
4. ital Network A CCITT standard for a network that accommodates a variety of mixed digital transmission services the access channels are basic rate 144 Kbps and primary rate 1 544 Mbps OSI Open Systems Interconnection An architectural model developed by the International Standards Organization ISO for the design of an open systems network All communi cation functions are divided into seven standardized layers Physical Data Link Network Transport Session Presentation and Application Packet A sequence of data with associated control information that is switched and transmitted as a whole refers mainly to the field structure and format defined with the CCITT X 25 recommendation Hot Topics v How packets are routed Wee the NETServer receives a packet it looks up the packet s destination in its routing table If a static route is found the packet is sent to the gateway listed If a static route is not found the NETServer will use a dynamic route If the routing table contains no routes to the destination it will send the packet to the Default Gateway If no such gateway has been defined the packet is discarded Establishing Connections to Remote Gateways The NETServer can easily forward a packet to a gateway for which there is an established connection such as a gateway on the same segment of the local LAN or at the other end of an active dial up connection All
5. ompts and the required responses However the NETServer will respond to a dial in PAP authentication request All that is needed is a User Table entry for the remote device CHAP Challenge Handshake Authentication Protocol Instead of actually sending a password over the link CHAP relies on a shared secret a password that both sides of the connection know but never send When a remote system requests CHAP authentication the authenticating host replies with a challenge packet The challenge packet contains among other things e A user name for the host The challenged system needs this to look up the correct shared secret password e A challenge value a randomly generated string of characters The challenged system then concatenates the challenge value with the shared secret and passes the new string through a hashing algorithm The authenticating host looks up the correct password for the user name received and then performs the same calculations the client performed comparing the result to the response value received
6. ote access to individual users through dialup lines The NETServer 8 and 16 let you connect to the corporate LAN to access email download files access Internet and Intranet web sites and interface with the corporate host The NETServer 8 and 16 I modem does everything the other NETServers do plus it allows analog or digital calls on all ports via ISDN Some network devices have more than one network interface allowing them to be attached to multiple network segments Such devices allow data from one end of a large network to be forwarded to the other end This process is called routing If a packet of data must pass through more than one routing device to reach its destination all the routing devices involved must know how to pass a packet onto the next router When the NETServer receives a packet that is addressed to another device it routes that packet towards its destination To make routing decisions the v Get remote access to individual users through dialup modem connections NETServer looks up the packet s destination in its Routes Table which contains the addresses of next routers called hops or gateways A gateway can be a host a server or any other device that performs routing functions v Typical Applications Log into an IP host via a remote terminal Create pools of modems that can be used by local hosts on a first come first served basis Establish dial
7. st to interact with this virtual terminal connection as if it was actually a serial port This makes the modem appear to be directly connected to the host Implement IP IPX Network Dial In IP IPX NETServer Network Dial In Access Remote IP and IPX users can dial in and attach to the local network as if they were local nodes IP and or IPX packets are transmitted over a dial in connection encapsulated in a serial line networking protocol PPP or SLIP When received by the NETServer the IP and IPX packets are forwarded from the remote user to the LAN and vice versa ninth LAN Port Local Network Dialup Routing The same routing engine that allows network dial in access allows the NETServer to establish dialup routing sessions with remote networks Such connections can be maintained continuously or established on an on demand basis and torn down when not needed Tech Glossary A miniglossary for the technical terms in this brochure Dialup line A temporary data connection activated by establishing a direct dialed telephone link between two modems IP Internet Protocol The protocol used in gateways to connect networks at the OSI Network Level Layer 3 and above IPX A communication protocol in Novell NetWare that creates maintains and terminates connections between network devices such as workstations and servers ISDN Integrated Services Dig
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