ssh -f [email protected] -L 2000:personal-server.com:25 -N

The -f tells ssh to go into the background just before it executes the command.

This is followed by the username and server you are logging into.

The -L 2000:personal-server.com:25 is in the form of -L local-port:host:remote-port.

Finally the -N instructs OpenSSH to not execute a command on the remote system.

example:

- for tunneling the remote mysql server to the local port 9000

ssh -L 9000:localhost:3306 [email protected] -nNT &

You might have noticed that every time we create a tunnel you also SSH into the server and get a shell. This isn’t usually necessary, as you’re just trying to create a tunnel. To avoid this we can run SSH with the -nNT flags, such as the following, which will cause SSH to not allocate a tty and only do the port forwarding.