Telnet is a user command and an underlying TCP/IP protocol
for accessing remote computers. Through Telnet, an administrator or another user can access someone else's
computer remotely. On the Web, HTTP
and FTP protocols allow you to request specific files from remote computers, but not to actually be
logged on as a user of that computer. With Telnet, you log on as a regular user with whatever
privileges you may have been granted to the specific application
and data
on that computer.
The result of this request would be an invitation to log on with a userid and a prompt for a
password. If accepted, you would be logged on like any user who used this computer every day.
Telnet is most likely to be used by program developers and anyone who has a need to use specific
applications or data located at a particular host
computer.
Related glossary terms:
system administrator (sysadmin), ring, Internet, keystone jack, corporate area network (CAN), port, home server, LANDesk Client Manager (LDCM), HomeRF (home radio frequency), local access and transport area (LATA)
Telnet
Telnet is the main Internet protocol for creating a connection
with a remote machine. It gives the user the opportunity to be on one
computer system and do work on another, which may be across the street
or thousands of miles away. Where modems are limited, in the majority,
by the quality of telephone lines and a single connection, telnet
provides a connection that's error-free and nearly always faster than
the latest conventional modems.
Using Telnet
As with FTP (see section Anonymous FTP), the actual command for negotiating a telnet
connection varies from system to system. The most common is
telnet itself, though. It takes the form of:
telnet somewhere.domain
To be safe, we'll use your local system as a working example. By now,
you hopefully know your site's domain name. If not,
ask or try
to figure it out. You'll not get by without it.
To open the connection, type
telnet your.system.name
If the system were
wubba.cs.widener.edu, for example, the
command would look like
telnet wubba.cs.widener.edu
The system will respond with something similar to
Trying 147.31.254.999...
Connected to wubba.cs.widener.edu.
Escape character is '^]'.
The
escape character, in this example
^] (Control-]), is
the character that will let you go back to the local system to close
the connection, suspend it, etc. To close this connection, the user
would type
^], and respond to the
telnet> prompt with the
command
close. Local documentation should be checked for
information on specific commands, functions, and escape character that
can be used.
Telnet Ports
Many telnet clients also include a third option, the
port on
which the connection should take place. Normally, port 23 is the
default telnet port; the user never has to think about it. But
sometimes it's desirable to telnet to a different port on a system,
where there may be a service available, or to aid in debugging a
problem. Using
telnet somewhere.domain port
will connect the user to the given
port on the system
somewhere.domain. Many libraries use this port method to offer
their facilities to the general Internet community; other services are
also available. For instance, one would type
telnet martini.eecs.umich.edu 3000
to connect to the geographic server at the University of Michigan
(see section Geographic Name Server). Other such port connections follow the
same usage.
