[c-nsp] Weird telnet problem on 7204VXR

Dennis Peng dpeng at cisco.com
Wed Oct 13 10:53:42 EDT 2004

Mike Bacher [isp-list at tulsaconnect.com] wrote:
> Dennis Peng wrote:
> >It's a bug. If you do a "show line vty X", you should see "Ctrl-C
> >Enabled" under the "Status" for the line. This causes the Username
> >prompt to timeout immediately when you try to use that line. It should
> >only effect one of the vty lines (although it may be vty 0 which is
> >the worst), but if you telnet back to the router right away, you
> >should get another line which should not have this problem. There is
> >no way to clear the condition, short of a reload.
> Ok, I tried two simultaneous telnet's and got in on one.  Also:
> dsl1#show line vty 1
>    Tty Typ     Tx/Rx    A Modem  Roty AccO AccI   Uses   Noise  Overruns   
>    Int
>      3 VTY              -    -      -    -    -     44       0     0/0      
>      -
> Line 3, Location: "", Type: ""
> Length: 24 lines, Width: 80 columns
> Baud rate (TX/RX) is 9600/9600
> Status: Ready, No Exit Banner, Control-c Typed, Ctrl-c Enabled
> Capabilities: none
> Modem state: Ready
> So, it looks like we are being bitten with the ctrl-c "bug" all of a sudden 
> (this hasn't been a problem until recently, and its been running for 
> several months with this IOS).  Is this problem caused by the previous 
> person that connected to that vty using Ctrl-C at some point?

Typing ctrl-c by itself won't cause the problem. You would have to use
a command which enabled ctr-c (to allow you to abort the command), but
didn't disable it correctly (like the atm ping command in older

> Is there a way just to disable the affected vty line or some other 
> workaround? This bug is hosing our ability to auto-provision DSL customers..

You can disable telnet as an allowed "transport input" so that it is
not used for telnet connections until you have the opportunity to
reload the router.


> -- 
> -----------------------------------------
> Mike Bacher / isp-list at tulsaconnect.com
> TCIS - TulsaConnect Internet Services
> Phone: 918-584-1100x110 Fax: 918-582-5776
> -----------------------------------------

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