Before gophers, hypertext, and sophisticated web browsers, telnet was the primary means by which computer users connected their machines with other computers around the world. Telnet is a plain ASCII terminal emulation protocol that is still used to access a variety of information sources, most notably libraries and local BBS’s. This report will trace the history and usage of this still popular and widely used protocol and explain where and how it still manages to fit in today.
HISTORY AND FUTURE OF TELNET
“Telnet” is the accepted name of the Internet protocol and the command name on UNIX systems for a type of terminal emulation program which allows users to log into remote computer networks, whether the network being targeted for login is physically in the next room or halfway around the globe. A common program feature is the ability to emulate several diverse types of terminals–ANSI, TTY, vt52, and more. In the early days of networking some ten to fifteen years ago, the “internet” more or less consisted of telnet, FTP (file transfer protocol), crude email programs, and news reading. Telnet made library catalogs, online services, bulletin boards, databases and other network services available to casual computer users, although not with the friendly graphic user interfaces one sees today.
Each of the early internet functions could be invoked from the UNIX prompt, however, each of them used a different client program with its own unique problems. Internet software has since greatly matured, with modern web browsers (i.e. Netscape and Internet Explorer) easily handling the WWW protocol (http) along with the protocols for FTP, gopher, news, and email. Only the telnet protocol to this day requires the use of an external program.
Due to problems with printing and saving and the primitive look and feel of telnet connections, a movement is underway to transform information resources from telnet-accessible sites to fully fledged web sites. However, it is estimated that it will still take several years before quality web interfaces exist for all of the resources now currently available only via telnet. Therefore, knowing the underlying command structure of terminal emulation programs like telnet is likely to remain necessary for the networking professional for some time to come.
ADVANTAGES AND DISADVANTAGES OF TELNET
The chief advantage to the telnet protocol today lies in the fact that many services and most library catalogs on the Internet remain accessible today only via the telnet connection. Since telnet is a terminal application, many see it as a mere holdover from the days of mainframe computers and minicomputers. With the recent interest in $500 Internet terminals may foretell resurgence in this business. Disadvantages include the aforementioned problems that telnet tends to have printing and saving files and its primitive look and feel when compared to more modern web browsers.
The functionality of the telnet protocol may be compared with the UNIX “rlogin” command, an older remote command that still has some utility today. Rlogin is a protocol invoked by users with accounts on two different UNIX machines, allowing connections for certain specified users without a password. This requires setting up a “.rhosts” or “/etc/hosts.equiv” file and may involve some security risks, so caution is advised.
Using telnet instead of the rlogin command will accomplish the same results, but the use of the rlogin command will have the effect of saving keystrokes, particularly if it is used in conjunction with an alias.