What Exactly Is Telnet? What Does It Do?

Telnet is a computer protocol that provides two-way interactive communication compatibility for computers on the internet and local area networks. It is famous for being the original protocol used when the internet first launched in 1969. Telnet provides a command line interface, a rudimentary interface by most standards. In time, Telnet's use declined in favor of SSH, due to serious security concerns when it was used over an open network. Telnet lacks authentication policies and data encryption.

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 to be a form of remote control to manage mainframe computers from distant terminals. In those 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.

In time, insecure Telnet evolved into a newer network protocol called Secure Socket Shell (SSH), which modern network administrators use to manage Linux and Unix computers from a distance. SSH provides strong authentication and secure encrypted data communications between computers over an insecure network.

Telnet is a text-based computer protocol. 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 now. 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 and can be used in Windows 10, Windows 8, Windows 7 and Windows Vista, although you may have to enable Telnet first.