PURPOSE OF THIS REPORT
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 full 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 a 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.
Some argue that the future of the Internet lies in sophisticated web
browsers like Netscape and Internet Explorer, or tools such as Gopher that
“save” end users from having to deal with the command line prompt and the
peculiar details of commands like Telnet. While that may be the case, the
tendency remains in place for programmers to develop new software by building on
the old. Therefore, knowing the underlying command structure of older protocols
like telnet and rlogin are likely to remain essential skills for the networking
professional in the forseeable future.