[c-nsp] Cisco IOS switch SSH connections not working

[Lee Starnes]

Hello everyone,

We started seeing an issue starting at 1:45am Sunday whereby we can no
longer connect to one of our switches via SSH. all the normal functions
seem fine, just can't get onto the switch.

When trying to connect to it, the session just hangs for about 30 seconds
and then says connection timed out. No login prompt.

So I did a little troubleshooting and I am not seeing the attempts even
make it to the ACL. No logs of failed or attempted connections.
Additionally, there are no active ssh or any vty sessions.

So then just to get the switch to restart ssh, I generated a new rsa key.
It stopped and restarted ssh, but nothing.

So attempted to just remove the ACL and try. Still nothing. Lastly, I
enabled telnet and tried to connect via telnet. Still nothing. I really
don't want to restart the switch if there is any other way to resolve this.

Anyone have any suggestions?

This is a 6509-e with dual SUPs, so possible to fail over to the other SUP,
but that also carries downtime with it as it causes the OSPF and BGP
sessions to reset.

Nothing in the logs either other than the last successful SSH alive check
from nagios.

Best,

-Lee