Telnet is a protocol that allows you to connect to remote computers (called hosts) over a TCP/IP network (such as the Internet). You use software called a telnet client on your computer to make a connection to a telnet server (i.e., the remote host). Once your telnet client establishes a connection to the remote host, your client becomes a virtual terminal, allowing you to communicate with the remote host from your computer. In most cases, you’ll need to log into the remote host, which requires that you have an account on that system. Occasionally, you can log in as guest or public without having an account.
Telnet clients are available for all major operating systems.
Command-line telnet clients are built into most versions of Mac OS X, Windows (95 and later), Unix, and Linux. To use them, go to their respective command lines (i.e., the Terminal application in Mac OS X, the shell in Unix or Linux, or the DOS prompt in Windows), and then enter:
Replace host with the name of the remote computer to which you wish to connect.