I have access to a Ubuntu Server (10.4) that I can't SSH into. From a terminal the connection times out and from putty the connection is refused. I have checked that sshd is running and listening on all interfaces, iptables has all chains empty and default is ACCEPT, additional firewall is accepting on port 22 inbound, and all outbound. I can't telnet into port 22 either. What could the problem be and how can I troubleshoot it?