Communications Server 0 Points

Configure the communication server (R1) so that when you type the host name of a router on the communications server, you are connected across the console port to that router:

■ Disable the break command on R1 so that R1 will not permit an intruder to issue a break command and perform password recovery. (Hint: Change the configuration register to 0x2002.)

■ Configure R1 as the communication server using the ip host command.

■ Communication server ports 2 to 5 are connected to Routers R2 to R5, respectively.

■ Communication server port 8 connects to the Catalyst 3550 series switch.

Communications Server Solution

Router R1 is configured for reverse Telnet. To enable reverse Telnet on the async lines 1 through 16, you must first enable Telnet. Example 8-1 allows reverse Telnet through lines 1 through 16.

Example 8-1 Enable Reverse Telnet on R1 Line 1 16

transport input all

After allowing for reverse Telnet (you could also apply the transport input telnet command, which permits Telnet only) on the async lines, define the reverse Telnet name and TCP port number. Line 1 uses TCP port 2001, line 2 TCP port 2002, and so on.

R2 is connected to Line 2, TCP port 2002, so the IOS command is as follows:

ip host R2 2002 local-ip- address

R3 is connected to Line 3, TCP port 2003, so the IOS command is as follows:

ip host R3 2003 local-ip-address The local IP address must be an active interface, so choose the loopback IP address. If the local IP address is assigned to a LAN or WAN interface and that interface happens to fail, your reverse Telnet connection will not work. R1 is assigned the loopback address The full configuration for R1 is displayed in Example 8-2. The PIX is connected to line 15, or TCP port 2015; the Ethernet switch is on line 8, or TCP port 2008 on the local router, R1. Example 8-2 configures R2 for local name lookup.

Example 8-2 Communication Server Solution on R1

ip host R2 2002 ip host R3 2003 ip host R4 2004 ip host R5 2005 ip host CAT5K 2008 ip host PIX 2015 line 1 16

transport input telnet

Example 8-3 displays a reverse Telnet connection on R1 to Router R2.

Example 8-3 Reverse Telnet to R2 on R1


Trying 2002 .

. Open

User Access Verification

Password: cisco


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