Cisco IOS Cookbook, 2nd Edition

Changing VTY Timeouts

Problem

You want to prevent your Telnet session from timing out.

Solution

To prevent Telnet (or SSH) sessions from timing out, use the following command:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#line vty 0 4
Router1(config-line)#exec-timeout 0 0
Router1(config-line)#exit
Router1(config)#end
Router1#

You can use this same command to simply increase the EXEC timeout to a large value, such as three hours, as follows:

Router1#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router1(config)#line vty 0 4
Router1(config-line)#exec-timeout 240 0
Router1(config-line)#exit
Router1(config)#end
Router1#

Discussion

By default, the router will terminate an EXEC session after 10 minutes of inactivity. Often administrators find that 10 minute inactivity timers are a nuisance and dislike having to log in to a router several times throughout the day. So Cisco provides a way to modify or disable the inactivity timer. It is important to note that this affects only timeouts due to inactivity. In Recipe 3.11, we discuss a way to disconnect sessions after a specified length of time whether they are active or not.

The exec-timeout command has two arguments:

Router1(config-line)#exec-timeout 240 0

The first argument is the length of time in minutes, and the second argument is seconds. This allows you to specify a timeout period as short as one second or as long as 35,791 minutes, which is over 24 days. ...