Server unexpectedly closed network connection

[User_4444_2]

When we upgraded the firmware on one of our 9509 switches, from 3.3(1c) to 3.3(4) we now can't login via SSH. We get the error message "Server unexpectedly closed network connection". I changed the login to allow Telnet and I can get in via that but not SSH. It has worked via SSH for the last 4 years and we have upgraded the code at least twice without issues.

Thanks

[dynamoxxx]

what ssh client are you using ? Have you tried with putty ?

[User_4444_2]

I'm using Putty but can't see that why that should make any difference, as it worked before the upgrade and works on switches with higher levels of code?

I have tried to remove and add the SSH keys without any luck.

[Prashanth Krishnappa]

Can you disable ssh server and then regenerate keys and renable ssh. Something similar to this

conf t
no ssh server enable
no ssh key
ssh key rsa1 2048 force
ssh server enable
end

[User_4444_2]

Tried that but get error the message "cannot delete/generate the keys problem in generating rsa key".

When I do "sh ssh server" I get "ssh is enabled but keys have not been configured to connect through SSH first generate keys".

Stuck in a loop.

[dakester]

Hi,

syslogd might be hung.  Can you "copy run start" ?

The upgrade also performed a system switchover.  Can you switch back?

Regards,

David

[User_4444_2]

We did a System Switchover but that didn't fix it. We can do an copy run start.

The logs seems to say we have a Back-Plane/Chassis issue.

[dakester]

Hi,

A partner support or Cisco TAC case is a good choice at this point.

Regards,

David

[shajji05]

I was having same issue and from GUI MGMT>Telnet-SSH I changed idle timeout from '0' to '5' minutes and it worked.