What’s Telnet?

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Telnet is a text-based network protocol developed in 1969 for simple terminal interaction. It helped revolutionize research and led to the creation of MUDs. However, due to security concerns, it is now rarely used for server management and has been replaced by SSH.

Telnet is a contraction of the two words Telecommunications Network and is one of the main network protocols used on the Internet. It is one of the first network protocols and one of the few original protocols still in common use on the Internet. It was developed in 1969, with RFC 15, and has evolved over the years to be a robust protocol, albeit with increasing security concerns it is often discounted in place of the secure SSH protocol.

Unlike the graphical interfaces to the HTTP protocol, which the World Wide Web gave us, telnet is a text-based protocol. The original purpose of telnet was to have a simple interface for terminals to interact with each other, using relatively simple command structures and accessible interfaces. While still in use, telnet is rarely used by the majority of the Internet browsing public, who instead use HTTP browsers and email clients for most of their connections.

In the pre-personal computer era, anyone who wanted to use a computer typically had to access a terminal attached to a huge mainframe. Originally, each terminal was connected to only one machine, which led to a variety of problems. For example, if a person needed to use a number of different machines, each specializing in a different task, he would have to physically go to each different terminal to do a job. This could be frustrating if the terminals were located in a large building, but it was especially infuriating if the mainframe you had to use was located in an institution in a different city or country than you.

The telnet protocol has helped overcome this difficulty. Using a simple suite of commands, users could access a remote terminal and ask the mainframe to run the processes they needed. The results would come back to them via telnet, and it was as if they were sitting at the terminal itself. In many ways, telnet helped revolutionize the way research was done and helped build what would eventually become the Internet we know today.

Of course, not all early uses of telnet were that practical. In fact, one of the ways telnet is still used to this day has its roots in 1978, when an Essex University student built on the earlier success of terminal games like Adventure and Zork to create a multi-user dungeon game, or MUD. These virtual environments, which include other varieties such as MUSH and MOO, allow multiple people to connect to a terminal via the telnet protocol. Once there, they can play a collective game, often fantasy-themed, by entering text commands and reading other players’ responses and inputs. Although the use of MUDs has declined with the advent of graphical massively multiplayer online role-playing games (MMORPGs), they still remain a major use of the telnet protocol, with hundreds of thousands of players worldwide.

While telnet was at one point used extensively as a protocol by network administrators and those who needed to manage their servers, it is rarely used for this purpose. In 1995, a researcher at the Helsinki University of Technology in Finland, fed up with the security holes in telnet that allowed for malicious password sniffing and attacks, created a new protocol to replace it. This protocol, Secure Shell, or SSH, has most of the same functionality as telnet, but has much more robust security.




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