The concept of port forwarding is relatively simple. Unfortunately, the command line that accompanies it tends to be a little cryptic, and there are some twists and turns to work through. The idea is to allow any connections made to a port on the local machine to be sent through the encrypted SSH connection to the remote machine, so connections that would normally be clear text (such as FTP, SMTP, or NNTP, just to name a few) can benefit from SSH security.