Before we explain how to use tredir, it is necessary to give some background on network services. We have talked about network services before, but we have not said exactly what they are.
Services are just that - services that are provided by the network.
Examples of services include telnet , which provides logins between machines, the File Transfer Protocol, ftp , which transfers files between machines, and smtp, the Simple Mail Transfer Protocol, which is used whenever you send electronic mail. Each network service has a port number associated with it. This file should be the same on all internet-connected machines. Each networked machine runs a daemon called inetd , which listens for attempts to connect to the network ports. These requests can come from either the network or the local machine.