When debugging issues on remote servers which appear overloaded, it is helpful to check if they are listening and accepting connections on a given port as a first heuristic.
Commands like telnet and netstat can be useful in these cases. To do a basic tcp handshake using netstat:
nc -zvw 1 <host> <port>
nc -zvw 1 localhost 22
The above command would return succeeded or failed depending on whether you have an ssh daemon running
-v flag specifies verbose output (to stderr),
-w specifies the timeout in seconds (in this case 1), so that this can also be used in non-interactive scripts.
-z makes sure that no data should be sent. You can find more details at: