Port forwarding is a powerful tool that can provide security to TCP/IP applications
including e-mail, sales and customer contact databases, and in-house applications. Port
forwarding, sometimes referred to as tunneling, allows data from normally unsecured
TCP/IP applications to be secured. After port forwarding has been set up, Secure Shell
reroutes traffic from a program (usually a client) and sends it across the encrypted tunnel,
then delivers it to a program on the other side (usually a server).. Multiple applications
can transmit data over a single multiplexed channel, eliminating the need to open
additional vulnerable ports on a firewall or router