Joy of Access: Telnet: An URL In Every Port?

A lot of special telnet services are on different “ports”. A “port” is a hole in the host that allows data to get in and out. Each Internet service has a standard port that it uses. Telnet uses port 23. If the place you want to get to uses a different port, you need to let the telnet software know. Usually, there will be a box to type the port number into. If you don’t know the port number, leave this box blank. If you do know the port number, go ahead and type it. If there is no box for the port, and you know that the port is a special one, try typing it after the hostname. Put a space between the hostname and the number. For example, to get to the Weather Underground, which has nothing to do with the rock group, the port is “3000”. You can type telnet madlab.sprl.umich.edu 3000.

In a URL, you’ll see the port after the host, separated by a colon. The URL for the Weather Underground is telnet://madlab.sprl.umich.edu:3000/. Normally, you don’t see the port specified in a URL, because most things use the default port for that service.