I have a strange problem and I'm not sure where to begin. My ssh client works on some servers but times out on others. Obviously, I checked that the servers are accessible via ssh from other locations. From my machine A I can log on to C only by logging on to B first. There are at least two servers for which this is the case. To make matters more strange sudo ufw status - Status: inactive nmap -sT -p 22 <problem_server> - ...22/tcp open ssh... On one affected server I am getting: ssh_exchange_identification: Connection closed by remote host and on the other I am getting ssh: connect to host <problem_server> port 22: Connection timed out With both of these servers I can log in from other machines. How can I troubleshoot such a problem?