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As the vendor of a telnet client application, we get many questions about what telnet is and how it works. We have written this page to help answer some of those questions. 

Definition of Telnet

The word telnet is derived from telecommunications network. Telnet is a protocol that provides remote terminal access to a host computer.  Instead of a terminal wired directly to a nearby host computer, telnet allows the terminal to be connected to a computer anywhere on a network or the Internet. This means that someone in California could connect to a computer in the New York City Public Library and search the card catalog the same way as someone located at a terminal in the library.

The computer that acts as a terminal is called the telnet client and the computer that acts as the host is called the telnet server. The telnet client computer must run an telnet client application (like TN3270 Plus) and the telnet server must run a telnet server application. The TCP/IP protocol is used to transmit information between the telnet client and the telnet server.

Links to More Information

Telnet -

Telnet -

The Telnet Protocol

Some Telnet Sites

Site Host name Port Terminal
New York City Public Library
(login: nypl) 23 VT100
Atomic clock in Boulder CO.
Displays the exact Mountain Standard Time, as determined by a government-run atomic clock and then disconnects. 13 VT100
Harvard University Library 23 3270
Library of Congress
Library of Congress copyright information, federal legislation ... 23 3270

 Let us know what other information you would like to see on this page.


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