inbound ssh ceased on 4 servers at same time

[greg at grokking.org]

John Brooks wrote:
> sshd is running on the affected machines
> 
> no errors on console or logs, just times out waiting for
> the password prompt. interestingly: when investigating this
> at the console, attempting ssh sessions from the db server
> and backup server to the file server (these two are 'deeper'
> in the network so there was never an occasion to ssh FROM
> them before) produced the std warning about an unknown host
> prompting for inclusion in the ~/.ssh/known_hosts file.
> 
> dns is not really involved, the ssh session is sent to the
> ip address directly as in "ssh john at 10.3.3.10"
> 
> ping works in both directions as does all other network
> services (internal mysql, intranet http, pop3, smtp, smbd, 
> nmdb, dns). network hardware and cabling issues have been 
> effectively ruled out.
> 


Have you tried ssh with the -vvv switch to get extra debugging info at
the console? If there's anything happening with ssh, it should show up
there, I'd expect. Are you testing to/from multiple hosts here? If so,
what's different between each set of hosts you're testing?

Hope that helps,
G