Set the telnet source IP address for a Cisco router

The default source IP address when telnetting from a Cisco router is that of the interface closest to the destination. Because some access lists may block traffic from the default IP address, or to help test access lists, it may be useful to temporarily or permanently set the telnet source IP address.

To temporarily set the telnet source IP address for a single telnet session, use the/source-interface extension to the telnet command. For example, to telnet to 192.168.1.4 using the source IP address of the interface FastEthernet0

telnet 192.168.1.4 /source-interface FastEthernet0


To set this interface as the source IP address for all telnet sesions, use this command in configuration mode (conf t):

ip source-interface fastethernet0