Port forwarding allows any TCP-based application or service to take
advantage of all the benefits of a secure tunnel between two hosts. After
you have set up a secure tunnel, the participating applications operate transparently.
For example, when you forward a regular TELNET connection through SSH, all
information, including your user name, password, and actual data, are automatically
encrypted and checked for integrity.
X11 port forwarding encrypts the X protocol (for X Window Systems).
Using SSH, you can invoke X Window programs on a remote machine and have them
appear on your local display. In this case, all X-protocol data is secured.
This chapter describes the following: