Computer Science @ Florida State University

Introduction to telnet

NOTE: Telnet has been disabled on all CS machines for security reasons. This means you cannot telnet INTO any CS machine. You can, however, still telnet to other hosts, but note that the telnet protocol does not encyrpt traffic, so it is therefore insecure.

Introduction

A basic Internet service is the provision of interactive login to a remote host. Telnet is both a protocol and a program that enables you to do so. It is the standard TCP/IP remote login protocol. This brief guide introduces Unix users to the use of telnet to conduct interactive sessions with remote host computers.

How to telnet

You must know the address of the remote host computer before you can initiate a session with telnet. Once you know the address, you can use telnet.

The syntax for using telnet is telnet (address of remote host)'

Example:

%telnet psupen.psu.edu (return)

will initiate an interactive session with the psupen host at Penn State University.

Many remote hosts require you to have an account to log in (You must have a user id and a password). However, some remote hosts do not require that users have accounts. Users can log in with a general user id such as info (or some other word that is published in guides to the Internet). Passwords are usually not required.

Example:

%telnet noc.sura.net (return) Login: info (return)

Figure 1 is an example of the login procedure for accessing a remote host that does not require users to have an acccount. The user id is PNOTPA (this is the general id for all users of this host. Users can look it up in various guides)

Figure 1

% telnet psupen.psu.edu  (return) 
trying... 
Connected to psupen.psu.edu0 

       			      PSU*PEN

		The Pennsylvania State University
Username:  PNOTPA  
Last interactive login on Thursday, 1-AUG-1991 13:14
Last non-interactive login on Tuesday, 30-JUL-1991 22:42

Press RETURN to continue

There is an alternative syntax for using telnet: telnet
The system responds with the telnet prompt: telnet>
The User types: open (address of remote host)
Figure 2 is an example of this syntax.

Figure 2

% telnet  (return)
Telnet:> open psupen.psu.edu  (return)
trying...
Connected to psupen.psu.edu0

       			      PSU*PEN

		The Pennsylvania State University
Username:  PNOTPA  
Last interactive login on Thursday, 1-AUG-1991 13:14
Last non-interactive login on Tuesday, 30-JUL-1991 22:42

Press RETURN to continue

If you are in telnet mode (i.e., the telnet> prompt is on the screen and you want to return to the Unix prompt without initiating an interactive session, type quit and press return:

telnet> quit (return) %

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