TELNET

What is Telnet?
Telnet in Windows
Open a Windows Telnet Session
Port 23
Telnet Commands
Download Telnet Programs
Telnet Sites

What is Telnet?

Before small and cheap personal computers, computers were expensive, slow and took up entire rooms. A typical network consisted of a few large, mainframe machines with many terminals connected through wire or cable. These terminals had no hard drives, processors or memory, they were "dumb" terminals. They had a screen, a monitor and a network connetion. The terminals were command line only and had no mouse. Without a connection to the mainframe, you could do nothing. The terminal was just a way of accessing the system.

As PCs became availble, most people still needed to access to a mainframe. Telnet is a network protocol that allows a terminal emulation on a PC; telnet allows a PC to behave like a terminal.

Telnet in Windows

Windows has a built-in Telnet utility(I recomend downloading a free version of another Telnet utitily at vandyke.com because the Windows version is fairly limited). This utility can be started several ways. The first way start the program yourself by double-clicking on the Windows icon. The executable is located in C:\WINDOWS. If you use this program often you may want to make a short-cut on the Desktop. The second way to start Telnet is to open a DOS prompt and at the prompt type telnet hostname or simply telnet. If you supply the telnet utility with a host name it will imediately bring up the telnet window and attempt to establish a connection, if you just type telnet the program will open and allow you to connect when you are ready.
Examples:
C:\WINDOWS> telnet univax.host.com
or
C:\WINDOWS> telnet
The third way is to type the telnet protocol into your browser's URL window (Location window). This is done by replacing the HTTP protocol with the telnet protocol.
Example:
telnet://univax.host.com
If you did not specify a host machine to connect to, you may do so once the telnet window is open. Click on the "Connect" menu(on some Telnet progams this may be under the "File" menu). Click on "Remote System..." A connection window should open up the a field for "Hostname or IP." Type in the hostname an click on the "connect" button.

Telnet will attempt to establish a connection to the host. This is where problem can happen. The best way to avoid problem connecting with Telnet when you first start using it is to already be connected to the Internet. Connect to the Internet with your browser and then open up a Telnet session.

If the hostname was entered correctly, the prompt on the screen should look something like this:
Welcome to univax.host.com
SunOS 5.1
No unauthorized access!

login:
Most hosts restrict access to their authorized users. Some hosts, however will allow guest access, by typing "guest" or "newuser" at the login: prompt. Some hosts will give you a free account if you send them an email request and answer a survey. Still other hosts have no user restrictions and allow a connections on demand. One such host is the CARL system. CARL is a virtual library card catalog database for over 400 university, public and private libraries. Connect to CARL at pac.carl.org. Once connected CARL can be used like any search terminal in library.

What a Telnet session might look like:

    Welcome to The Host
    Authorized users only!


Username: tjones
Password: *******

    User tjones logged on
    You have 1 new mail message

user\tjones> _
You may Telnet to a standard address or an IP number:
telnet pac.carl.org
telnet 192.54.81.18
Same thing

Open a Telnet Session

If you are using Windows click here to open a Telnet session

Port 23

The telnet port is usually port 23. If a server is configured correctly, it will find the port for you. However, you may need to add it to your IP number.
telnet 192.54.81.18:23

Sometimes the telnet port is very busy and is divided into sub-ports. If this is the case, try adding two digits onto the 23 to make it a four digit number. Try variations until you get through:
telnet 192.54.81.18:2355
or
telnet 192.54.81.18:2394



Telnet Commands

openConnect to a site
closeClose connection
quitClose telnet program
statusShow staus information
?Help
zSuspend
fgActivate suspended session



Telnet Programs

vandyke.com
Telnet Documentation
Telnet programs for Windows and Macintosh
Unix Telnet Scripts
Telnet on a Mac
Various Telnet Clients



Telnet Sites

Telnet: cyberspace.org         Http: cyberspace.org
Telnet: bbs.gaianet.net         Http: bbs.gaianet.net
Telnet: ned.ipac.caltech.edu         Http: ned.ipac.caltech.edu