[c-nsp] Telnet session dropped

[Randy]

--- On Mon, 12/26/11, Roy <r.engehausen at gmail.com> wrote:

> From: Roy <r.engehausen at gmail.com>
> Subject: [c-nsp] Telnet session dropped
> To: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
> Date: Monday, December 26, 2011, 1:08 PM
> I use RANCID ton a number of
> routers.  About five days ago, it started failing on
> three routers.  If I manually connect to these routers,
> it seems to work for a minute or so and then the telnet
> session gets disconnected.  The disconnect only occurs
> during a data transfer such as "show conf"
> 
> I tested it from several places so the telnet client
> doesn't seem to be a factor.  The routers are all on
> different ISPs and in different cities.  The only
> common denominator between the failing routers is they are
> all set to use a port other than 23.  This is done by
> natting the external port to port 23 on a null interface.
> 
> Rebooting the routers didn't help
> 
> Any ideas?


I wonder if your isps have decided to blackhole tcp traffic on port that you redirect to 23. A quick test to confirm would be to try without port redirection(terribly insecure) or use ssh. I have been bitten by XO..
./Randy