What Exactly Is Telnet and What Does It Do?

Connect to other computer systems using a fast, simple protocol

Teletype Network Protocol. Telnet Virtual terminal client. Internet and Network concept. Telnet.
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Telnet is a computer protocol that provides two-way interactive communication compatibility for computers on the internet and local area networks. Telnet has a command-line interface and is famous for being the original protocol from when the internet first launched in 1969.

In time, Telnet's use declined in favor of SSH (Secure Shell or Secure Socket Shell) due to serious security concerns when it was used over an open network. Telnet lacks authentication policies and data encryption.

The Beginning of Telnet

Telnet refers to a network virtual terminal protocol. The acronym comes from teletype network, terminal network, or telecommunications network, depending on which source you believe, and it was built as a form of remote control to manage mainframe computers from distant terminals.

In the days of large mainframe computers, Telnet enabled research students and professors to log in to a university mainframe from any terminal in the building. This remote login saved researchers hours of walking each semester.

While Telnet pales in comparison to modern networking technology, it was revolutionary in 1969, and Telnet helped pave the way for the World Wide Web in 1989.

Telnet window screenshot

Telnet Gives Way to SSH

In time, insecure Telnet evolved into the newer SSH network protocol, which modern network administrators use to manage Linux and Unix computers from a distance. SSH provides strong authentication and secures encrypted data communications between computers over an insecure network.

No Graphics Here

Unlike Firefox or Google Chrome screens, Telnet screens are unremarkable to view. Telnet is all about typing on a keyboard. It has none of the graphic elements we expect from web pages today. Telnet commands can be rather cryptic, with example commands including z and prompt% fg. Most modern users would find Telnet screens to be archaic and slow.

Telnet is almost never used to connect computers anymore because of its lack of security. However, it is still functional; there's a Telnet client in Windows (10, 8, 7, and Vista), although you may have to enable Telnet first.