Lab 4: Configuring an Access Server-Part II

Lab 4: Configuring an Access Server ”Part II

Lab Walkthrough

After connecting all the console ports to the octal cable of your access server, you can begin to configure the access server to support reverse Telnet sessions. To configure a reverse Telnet session, you need to know what the absolute or line entry numbers are for the TTY lines that you are working on. To display the line entries, perform the show line command. In Example 1-49, the line entries are from 1 to 16 for the TTY session. You have two to five routers in this lab, so you use the values 2001 to 2005 for a Telnet port on reverse Telnet sessions.

Example 1-49 Display of the show line command

 Router#  show line  Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int *  0 CTY              -    -      -    -    -      0       1     0/0       -    1 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -    2 TTY   9600/9600  -    -      -    -    -      0       1     0/0       -    3 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -    4 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -    5 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -    6 TTY   9600/9600  -    -      -    -    -      0       1     0/0       - *  7 TTY   9600/9600  -    -      -    -    -      0       2     0/0       -    8 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -    9 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   10 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   11 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   12 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   13 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   14 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   15 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   16 TTY   9600/9600  -    -      -    -    -      0       0     0/0       -   17 AUX   9600/9600  -    -      -    -    -      0       0     0/0       -   18 VTY              -    -      -    -    -      0       0     0/0       -   19 VTY              -    -      -    -    -      0       0     0/0       -   20 VTY              -    -      -    -    -      0       0     0/0       -   21 VTY              -    -      -    -    -      0       0     0/0       -  Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   Int   22 VTY              -    -      -    -    -      0       0     0/0       - Router# 

Now that you know the absolute line values, you can configure the access server to support reverse Telnet. From the configuration mode, enter a host name of access-server, followed by the lines that you need for the reverse Telnet sessions. Enter ip host r1 200 x 201.201.1.1, where x ranges from 1 to 5. You also need to add a Loopback 0 interface with an IP address of 201.201.1.1/24. Example 1-50 illustrates this process.

Example 1-50 Configuration of IP Host Names for Reverse Telnet Sessions

 Router# Router#  conf t  Enter configuration commands, one per line.  End with CNTL/Z. Router(config)#hostname access-server access-server(config)#  ip host r1 2001 201.201.1.1  access-server(config)#  ip host r2 2002 201.201.1.1  access-server(config)#  ip host r3 2002 201.201.1.1  access-server(config)#  ip host r3 2003 201.201.1.1  access-server(config)#  ip host r4 2004 201.201.1.1  access-server(config)#  ip host r5 2005 201.201.1.1  access-server(config)#  interface loopback 0  access-server(config-if)#  ip address 201.201.1.1 255.255.255.0  access-server(config-if)#  exit  access-server(config)# 

The final part of configuring an access server involves configuring the line entries to support reverse Telnet. This can be accomplished by adding transport input all on the appropriate lines. In this particular lab, we will go one step further and reduce contention for the line by adding the no exec command. This is only for convenience, and it is not a requirement of configuring a reverse Telnet session. Example 1-51 completes the access server's configuration for reverse Telnet.

Example 1-51 Configuring the Absolute Lines for Support of Reverse Telnet, and Disabling the Exec

 access-server(config)#  line 1 5  access-server(config-line)#  transport input all  access-server(config-line)#  no exec  access-server(config-line)#  ^Z  access-server# 

To test the configuration, simply key in r1, and a session opens to R1. If this session is rejected, be sure to perform a clear line x, where x is the absolute line number of the session that was rejected. Example 1-52 lists the entire configuration of the access server.

Example 1-52 Complete Listing of a Router Configured as an Access Server

 access-server#  wr t  Building configuration... Current configuration: ! version 12.0 service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname access-server ! ip subnet-zero ip host r1 2001 201.201.1.1 ip host r2 2002 201.201.1.1 ip host r3 2003 201.201.1.1 ip host r4 2004 201.201.1.1 ip host r5 2005 201.201.1.1 !  interface Loopback0  ip address 201.201.1.1 255.255.255.0  no ip directed-broadcast ! interface Ethernet0  no ip address  no ip directed-broadcast  shutdown ! interface Serial0  no ip address  no ip directed-broadcast  no ip mroute-cache  shutdown ! interface Serial1  no ip address  no ip directed-broadcast  shutdown ! ip classless ! line con 0  transport input none line 1 5  no exec  transport input all line 6 16 line aux 0 line vty 0 4 ! end access-server# 

The final part of the lab instructed you to configure the Telnet session so that it would not time out after a period of inactivity. To accomplish this, add the command no exec-timeout on Line 0, the console port of the routers connected to the access server. Adding this command forces the routers not to time out the console port and log you off because of inactivity.