Last night I had to change my network range from 192.168.0.xxx to 192.168.1.xxx. This has stopped sshd from working on my CentOS server. It's definitely something to do with the new IP range, because if I switch back to the old range, sshd works and I can SSH in.

Before you ask, I updated iptables for the new range, and running sshd in debug mode shows that it DOES receive my connection attempts, but it hangs after a moment (i.e. before I am even asked to accept the host key) This server also runs Apache which still works fine on the new IP range. Samba and Subversion both seem to be dead.

Any ideas folks? I have a feeling I need to regenerate some host keys or something to that effect.

Have you checked your SSH configuration file to ensure its listening on the right interface. Also do you have entries in your TCP Wrappers, so look at /etc/hosts.allow and /etc/hosts.deny.

That was it - thank you. SSH is now working I also found the subversion conf file and fixed that up.