Kevin Dorrell, CCIE #20765

13 Mar 2008

IOS Gotcha : no exec

Filed under: IOS features — dorreke @ 05:30

Here is a great one.  I don’t like my console timing out.  Let’s cancel the timeout.  The correct command is exec-timeout 0 0, but you can do it with no exec-timeout.  I’m even lazier:

R2#conf t 
Enter configuration commands, one per line.  End with CNTL/Z. 
R2(config)#line con 0 
R2(config-line)#no exec 
*Mar  1 14:37:03.697: %SYS-5-CONFIG_I: Configured from console by console 

Five minutes later, my console times out.  Not only that, but it seems to have locked up.  What is going on? 

Luckily, I am well advanced in my lab, and I can telnet from another router.  Let’s have a look:

R2#show run | sec con 
Building configuration... 
Current configuration : 4296 bytes 
no ip dhcp use vrf connected 
 redistribute ospf 100 include-connected 
 redistribute connected 
line con 0 
 privilege level 15 
 logging synchronous 
 no exec 


Normally if a command is ambiguous, the CLI comes back and tells you so.  Not in this case.  Gotcha!



  1. What to do if I did not configure telnet from another router like you have?

    Comment by Manish — 03 Oct 2012 @ 16:50

    • Well, as long as you have not committed it to the startup configuration, you should be OK with a power cycle. (Not so practical if it is at a remote location though.) Otherwise I guess you are left with the password recovery procedure.

      Comment by dorreke — 04 Oct 2012 @ 03:51

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