Apologies, not a networking guru, otherwise I'd know the answer to this !

I've previously been able to use putty to ssh onto a server. The server was configured to prevent root having ssh access and, instead, I would log in with a user called gecko_user which was accompanied by a PPK file.

In the last 48 hours, the Linux controller concerned has had its password authentication mechanism changed from DES to SHA512. This might be a red herring, but since then I can no longer ssh onto the server. I'm getting "PuTTY fatal error. Network error - connection refused".

Do I need to re-generate the PPK file, or otherwise how do I analyse what the issue might be ?

Thanks

This would indicate a network problem rather than an authentication issue. What happens if you attempt the connection without using the keypair?

Hi TenTenths,

Same error even if I leave out the key file.

So it's a network problem and nothing to do with the authentication.

Then I'm a bit lost ...
Not sure if sshd itself is refusing, or if it is something higher up the stack.
I'm guessing there's an ssh server log somewhere and will check that out, but the IP address is certainly pingable.