Local port forwarding (an outgoing tunnel) forwards traffic coming to a local port to a specified remote port.
Example: On Unix, when you issue the command
$ ssh2 -L 1234:localhost:23 username@host
all traffic coming to port 1234 on the client (localhost) will be forwarded to port 23 on the server (host).
Note that the localhost definition will be resolved by the SSH Tectia Server after the connection is established. In this case localhost therefore refers to the server (host) itself.
Note: It is important to understand that if you have three hosts, client, sshdserver, and appserver, and you forward the traffic coming to the client's port x to the appserver's port y, only the connection between the client and sshdserver will be secured. See Figure Forwarding to a third host. The command you use would be similar to the following: