Putty Command Line – How to Enable KeepAlive

Here is a series of steps you can use to diagnose the problem:

1. Check if sshd is running on the host(ps -ef|grep ssh)
2. Ensure that sshd is binding to port 22 using netstat (netstat -al|grep "LISTEN " should work)
3. See if you can connect to the real IP address via ssh from the host machine (if not, there is either a local firewall, or sshd is not working as it should
4. Try to ping the host from the client machine (if this fails, there is a routing problem)
5. Try to telnet to port 22 from the client machine (telnet 192.168.1.1 22) (if this fails, a firewall is blocking you)
6. Finally, if all the above succeed, but you cannot ssh using the ssh client - re-install your ssh client.

Are you sure that root login to ssh is allowed?

Check sshd_config and verify that root login is permitted. sshd will need to be restarted if the setting changes.