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MAP11: TELNET (PART ONE)


     "Thanks to the interstate highway system, it is now possible
      to travel across the country from coast to coast without
      seeing anything." -- Charles Kuralt, On the Road


We are about to enter a new section of this workshop. For the past
week, we have talked about communicating on a one-to-one basis
(e-mail) and on a one-to-many basis (LISTSERV and Usenet).

Today, I'm going to show you how to log in to other computers around
the world and take full advantage of the public programs and services
that these other computers offer.

There is some bad news, though. Some of you, especially a good
number of you with "level one" Internet access, do not have access
to TELNET. If this is true for you, please accept my apologies.
I promise to make it up to you next week when I show you File
Transfer Protocol -- and besides, you can always take today's lesson
and tomorrow's lesson and bug your local Internet provider into
offering TELNET (you can also save this lesson for the day
that you do have TELNET access).

With TELNET, the commands that you type on your keyboard are sent
from your terminal to your local Internet service provider, and
then from your provider to the remote computer that you have
accessed. Unlike the LISTSERV commands that you sent last week
that took CENTURIES to process (okay, a *slight* exaggeration),
TELNET commands (usually) travel so fast that you can't even
tell that you are using a remote computer.

So what can you do with this ability to log into remote computers?
If your local Internet provider allows it, it is possible for you
to TELNET into your account from another city and check your e-mail
while you are on vacation or away on business. You can also TELNET
into huge databases to do research, or even TELNET into libraries
around the world to check if they have a certain book that you
are looking for. TELNET also offers an easy entry into the world
of Gophers and the World Wide Web for those people who may not
otherwise have access to these tools.

Last Tuesday (in MAP04: E-MAIL), I showed you that an Internet
address for a user looked something like: user@address. Well, since
we are no longer interested in the person -- we want to access the
computer, not the person -- we can throw away both the "user" and the
"@" part. All we care about now is the stuff *after* the @.

TELNET addresses look something like this:

     seabass.st.usm.edu        cybernet.cse.fau.edu
     bbhost.hq.eso.org         fedworld.gov
     128.118.36.5              192.160.13.1

Gee ... that's easy. Also notice that TELNET addresses can be
in domain name format (i.e. seabass.st.usm.edu) or in IP
address format (i.e. 120.118.36.5). (Note: both the domain
name system and the IP address system were discussed in MAP04:
E-MAIL).

You may also see TELNET addresses with numbers stuck on the
END of them. Those numbers are "port" numbers. Port numbers don't
have anything to do with hardware ports on the computer; instead
they are (sort of) a way for you to tell the remote computer which
program or server you want it to pull up. A TELNET address with a port
number allows you not only to access a remote computer, but to also
pull up a specific program or server on that remote computer (BTW, the
standard port number is port 23):

     seabass.st.usm.edu 23     cybernet.cse.fau.edu 2010
     bbhost.hq.eso.org 6969    fedworld.gov 4242
     128.118.36.5 23           192.160.13.1 66

We seem to have the addresses down pat. Now for the fun stuff!

There are seven steps to a successful TELNET session. These steps
are all based on simple common sense, and I will explain them all
in a minute. But first, here are the seven steps:

     1. Start-up the TELNET program
     2. Give the TELNET program an address to connect to
        (BTW, some really nifty TELNET packages allow you
        to combine steps 1 and 2 into one simple step!)
     3. Make a note of what the "escape character" is
     4. Log in to the remote computer
     5. Set the "terminal emulation"
     6. Play around on the remote computer
     7. Quit

Now let's talk about each of these steps. There are a lot of different
TELNET software programs around, but each of these programs operate on
the same basic principles. (BTW, my explanation may be a little
"mainframe-y" but you will soon discover that you can easily
translate my explanation so that you can use TELNET in Windows
or on a Macintosh).

Starting the TELNET program is easy. All most of you have to do is
type the word TELNET on your command line, and the program will
start right up. If you are using Windows or a Macintosh (or
an equivalent), double-click on the TELNET icon.

The second step is to give the TELNET program the address of
the computer that you want to access. This is where the programs
start to differ. Some programs will automatically ask you to enter
the address of the remote host, but most won't. If your program
does not automatically ask you for the address, you need to type

          open <site address> <port number>

on the command line. For example, to get TELNET access to
YALEINFO.YALE.EDU 7000, you would type OPEN YALEINFO.YALE.EDU 7000.
(If you are using Windows or a Mac, the OPEN command may be
located on a pull-down menu). If you don't include the port
number, TELNET will automatically assume that you want to
connect to port 23.

Remember when I said that some nifty TELNET programs allow you
start-up the TELNET program and access the address all in one
easy step? Instead of doing the two steps I just went over, you
may be able to just type

          telnet <site address> <port number>

on the command line (for example: TELNET YALEINFO.YALE.EDU 7000).

After you have told TELNET which computer you want it to access, and
right before you gain access to the remote computer's login screen,
you will see something like this:

     telnet YALEINFO.YALE.EDU 7000
     Trying 130.132.21.53 Port 7000 ...
     Connected to YALEINFO.YALE.EDU
     Escape character is ...

This tells you that your TELNET program is trying to access the
YALEINFO.YALE.EDU 7000 address, gives the IP address for YALEINFO
(remember those from MAP04?), tells you when you are connected,
and gives you the escape character. REMEMBER THE ESCAPE CHARACTER!
You are going to need it in a second :)

The next step is to log in to the remote computer. Everyone should
know how to log in to a computer by now ;)    <=== a winking smiley

If you are accessing a public site, the "login" -- the "password"
that you need to access the remote computer -- will probably be
publicly known. For example, tomorrow I will send you a list of
several dozen TELNET sites, including their addresses and logins.
Some public sites even TELL you what the login is when you TELNET
to them! Heck, some TELNET sites are wide open and do not require
a login or password at all!!

The fifth step is to set the terminal emulation. All this means is that
you are going to tell the remote site how data should be shown on
your screen. The most common terminal emulation setting is VT100,
which is the standard for terminal-based communications.

If you do not have a VT100 terminal, or a terminal that can pretend
its a VT100 terminal. you may have to set your terminal emulation
to either your correct terminal type or, if you do not know your
your correct terminal type, to a "dumb" terminal emulation.

Fortunately, some TELNET sites automatically take care setting the
terminal emulation for you, so you don't even have to worry about
it.

If you end up with a screen full of gibberish, chances are you did
not use the correct terminal emulation setting. Your best bet if this
happens is to disconnect from the site and try again.

I think you can figure out the sixth step -- play around on the
remote computer -- all by yourself :)

The final step is to quit. Some sites are nice and tell you how to
do this, but most expect you to figure out how to quit on your
own. That is where the escape character comes in!

Remember that once you access the remote computer, every keystroke
of yours will be carried out not on your computer but on the remote
computer! Typing the escape character (usually the control key and the
right bracket key pressed at the same time) temporarily interrupts
your TELNET session and puts you into the TELNET command mode.

Once you are in the command mode, you can use a couple of commands:

     CLOSE       Closes your TELNET connection to the remote computer
                 and either returns you to the command mode (if you
                 started in the command mode) or quits TELNET.
     QUIT        Quits the TELNET program; if you are connected to
                 a remote computer, QUIT will disconnect you from
                 the remote computer and then quit TELNET.
     SET ECHO    If you can't see what you are typing, or if you
                 type and see double, this command should take
                 care of the problem
     <ENTER>     (or <RETURN>) Pressing the enter or return key
                 will take you out of TELNET command mode and
                 return you to your TELNET session.
     OPEN        Opens a connection to a remote computer

So, if you are in the middle of a TELNET session and you decide
to quit, you would type the escape character to enter the TELNET
command mode, and then type the word QUIT.

One last thing and I will let you go: regular TELNET does not
work if you are trying to TELNET to an IBM 3270 mainframe computer.
You'll have to use TN3270 instead. It works just like TELNET,
only the keys on your keyboard may change a little (IBM uses
something called map3270 to lay out the keys, and IBM uses a
lot of function keys).

HOMEWORK

     Study this lesson carefully. Tomorrow I am going to send
     you a huge list of TELNET addresses, and turn you loose
     to wreak havoc on the Internet :)

     Also, a not-so-subtle hint: we just ended one section of
     the workshop and entered a new one. What does the teacher
     usually give you when a class section ends?

     Study hard >:)        <===== that's a devil smiley


   PATRICK DOUGLAS CRISPEN    THE VIEWS EXPRESSED IN THIS LETTER DO NOT
    [e-mail]      NECESSARILY REPRESENT THE VIEWS OF THE
  THE UNIVERSITY OF ALABAMA      UNIVERSITY OF ALABAMA - TUSCALOOSA

      ROADMAP: COPYRIGHT PATRICK CRISPEN 1994. ALL RIGHTS RESERVED.