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New Member

ssh connectivity lost after power failure

Hello all, My first question to this forum, not going to be my last. I'm new to networking at this level.

We have a remote 6506, the entire datacenter lost power due to a UPS failure. Now the 6506 seems to be switching correctly, but can no longer SSH into it, and even thought telnet was turned off - now we can telnet to it.

Is this normal, of all it's configuration parameters it only forgot it's ssh/telnet after a powerfailure?

I want to turn on the ssh and turn off the telnet with out messing anything else up. Any help? Thanks!

6 REPLIES

Re: ssh connectivity lost after power failure

If you configured SSH and removed telnet, but forgot to save the config, the switch would use the saved config, not the running config. Check to see if SSH is enabled-

sh ip ssh

If not try configuring it-

SwitchOne(config)#crypto key generate rsa

Enter modulus: 1024

SwitchOne(config)#ip ssh time-out 60

SwitchOne(config)#ip ssh authentication-retries 2

Try the command again to see if it's running-

sh ip ssh

Reply when you get this far and we'll continue to troubleshoot.

New Member

Re: ssh connectivity lost after power failure

This turned on ssh, can now ssh to the switch, but how do you turn off telnet?

Re: ssh connectivity lost after power failure

Under your VTY's, set the input to SSH only.

line vty 0 15

transport input ssh

You can further restrict who can access the switch by using an ACL and access class under the VTY.

New Member

Re: ssh connectivity lost after power failure

Thanks that did it!

Bronze

Re: ssh connectivity lost after power failure

Besides checking what Collin suggested, you might want to make sure you saved the SSH keys in NVRAM.

show crypto key mypubkey rsa

If they don't show up, you might have to create new keys.

This is probably a case of forgetting to "copy run".

New Member

Re: ssh connectivity lost after power failure

Not sure if this applies here but I've had some issues in the past where I can no longer connect using SSH after a failover or swapping out hardware. Normally recreating the cert fixes it.

crypto key generate rsa

As long as you have the following under your telnet lines it should use SSH and not telnet. Remember to put it on both 0 4 and 5 15.

transport input ssh

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