telnet on their MS-Windows systems. Assignment 2 requires students to use this
software, so this Web page contains some hints which should make your
task somewhat easier.
telnet which we believe was derived (or
copied) from the original Trumpet Winsock
project. This version had excellent features, and is recommended if it's
available to you.
Before you can use telnet to exercise the various
Internet applications protocols, you have to configure a couple of
variables. Start telnet from the "Run" menu --
simply type telnet into the dialog box which it
presents to you. Click on the
Terminal -> Preferences ...
menu option. In the preferences window, make sure the "Local Echo"
checkbox is selected. This looks like:
You should also click on the
Terminal -> Start Logging ...
and specify a "log" file, where the contents of the session will be
saved to a textfile. You can later open this textfile in any text
editor, such as "Notepad", or even in your favourite Word Processor
package. The logging menu will look like:
You are now ready to use
telnet to exercise one of
the Internet application protocols. Select the
Connect -> Remote System ...
menu option. Enter the desired hostname and port number (replace the
default value of Telnet with the port number you're
interested in, eg 80) into the dialog window. It will look something like this:
You can now click the "Connect" button, which will pop open a "terminal window". Try typing (for example) an HTTP command, such as:
This will scroll the server's response very quickly, and then offer a "Close Window" alert box. Close it, and quitGET / HTTP/1.0
telnet. Then open the log file with the Notepad
text editor and peruse the HTTP response headers and the HTML
document.
You can start up telnet from the "Run" menu
directly with a hostname and port number specified, for example:
The example as shown here will establish a TCP connection to port 80 on machine
ironbark.bendigo.latrobe.edu.au, allowing the user to
(for example) send an HTTP "GET" command. You'll possibly have to set
"local echo" in the Preferences dialog, and configure a log file (both
as discussed above) before it'll be useful to you.telnet command shipped with Windows
2000 is a very sad piece of software. It is nowhere near as useful as
the version from Win95/98. Here's a list of what's wrong with it:
telnet utility. In effect, it's really only
useful for performing "remote login". It's certainly not much use for
us! However, here's a brief discussion of how to use it -- it may be
useful to you.
As before, start up telnet from the "Run" menu, as
follows:
This produces a window which looks something like a "Command Shell" or "DOS" window, Because it's a command-line program, you can type "Help" and see a rudimentary list of the available commands:
In order to exercise Internet application protocols running on specific port numbers, you must set "local echo". You can check the status of this (and other options) by typing "display", or "status":
Microsoft Telnet> set LOCAL_ECHO Microsoft Telnet> display Escape Character is 'CTRL+]' WILL AUTH (NTLM Authentication) LOCAL_ECHO on Sending both CR & LF WILL TERM TYPE Preferred Term Type is ANSI Microsoft Telnet> Microsoft Telnet> open ironbark.bendigo.latrobe.edu.au 80 Connecting To ironbark.bendigo.latrobe.edu.au... Microsoft Telnet> display Escape Character is 'CTRL+]' WILL AUTH (NTLM Authentication) LOCAL_ECHO on Sending both CR & LF WILL TERM TYPE Preferred Term Type is ANSI Microsoft Telnet>
telnet which you have access
to is the Win 2000 utility, you should consider downloading one of the
excellent "Freeware" or "Shareware" versions. Check out, for example,
the collection on AARNet's
Tucows
mirror (search for "telnet"). One of
the best is Teraterm
Pro. It's freeware, and is available on all of the major
"mirror" sites, or you could simply download version 2.3 from here. It's easy to install.
An alternative is PuTTY, which is nice because it's not an "install", it's simply
a double-clickable application. Nice.TeraTerm Pro has a few configuration options that are not entirely obvious. I suggest you use the following steps. When you first start it, you will normally be looking at a window like this:
Click the "Cancel" button. Then select the
Setup -> TCP/IP menu option. This
dialog allows you to "keep windows" after the TCP connection is closed.
Click the appropriate checkbox next to "Auto window Close", as follows:
Now select the
Setup -> Terminal menu
option. You have to make a few changes here. Configure it to turn on
"local echo", and also ensure that "Transmit CR+LF"
is selected (although it's OK to have "Receive CR"
selected). It should look something like the following:
Now we're ready to go. Click the
File -> New connection...
option. Type in the desired hostname and port number. For example, to
connect to port 80 on ironbark it would look like this:
Once connected, you could issue one of the HTTP commands. For example, to get the
ironbark "home page", you could type the following.
Note that I've "scrolled back" to the top of the window in this
snapshot.
Incidentally, notice that the response from
ironbark is not
formatted nicely, That's because whilst the protocol messages are
terminated by telnet <CR><LF> (carriage return/line feed)
pairs, the actual document which is served uses the Unix <LF>
newline convention. You can possibly play around with the
Setup -> Terminal dialog: try setting
it so that you always transmit CR+LF but receive
CR only, for example.
For example, if you're having difficulty establishing a connection to
port 80 on ironbark (the example I used above), it could be
that you're behind a firewall and you have to connect to a local proxy
server instead. Try establishing connections to other port numbers on
ironbark: 23 is the telnet default, and should give a
"login" message.
You could also try port 7 (echo), port 13 (daytime), 21 (FTP control),
25 (email), 79 (finger) and port 110 (pop). If you get a "Connection
established" message for any of these, but not for others, you may be
"behind" a firewall. If *none work, you almost
certainly are behind a firewall.
You could also check the configuration on your Web browser: if you're
using IE it's under
Preferences -> Network -> Proxies.
If the "Use proxy" box is checked, and a proxy server is specified
there, then that's your problem. If this is so, then you'll only be
able to connect to servers on "your side" of the proxy -- perhaps your
own ISPs Web server, for example. If you can identify a server that's
accessible to you, try connecting to the port numbers mentioned above
and see if you can establish a TCP connection.
telnet to
do "command-line" (shell) login to the university's Unix systems, then
don't. Don't even think about it
for regular use (ie, it's OK occasionally, but don't make a habit
of it...). Why not? The reason is that telnet is, as we know, a simple
line-oriented protocol, meaning that all communications (including
your username and pasword) are sent as plain text.
An observer could easily "packet sniff" them. Unless you're pretty
sure that the network you're using is secure, you should use
something else.We recommend you to use a "terminal" utility that encrypts your communications. Any software which implements the Secure Shell (ssh) protocol is suitable. For Windows, our favourite is the ssh extension to TeraTerm Pro, which can be found at http://www.zip.com.au/~roca/ttssh.html Its free, it's easy to install and it was written is Australia. Its use is recommended if you really do want to do remote (shell) login to a Unix system. Another good (and free) alternative is PuTTY, mentioned above, which implements ssh very nicely.
Furthermore, the authors of this page are not in a position to comment on the suitability of any software mentioned here for your particular machine. You are on your own if you choose to install any such software. Notwithstanding that, we believe that everything in this page is correct, and we do not believe that you should suffer any harm as a result of following our recommendations.
This page should not be taken as recommending the use of any particular operating system or machine. We are not recommending the use of MS-Windows, nor are we recommending against its use. The information here is provided in good faith in the hope that it will be useful to persons who are already using MS-Windows.
