In this lesson, we are going
to learn about telnet, ftp, ping, and traceroute.
Telnet is a utility
that allows a computer user at one site to make a connection, login
and then conduct work on a computer at another site. For example, you
can use the telnet command to run a program in your directory on a supercomputer
thousands of miles away. Telnet runs on TCP/IP port 23. Similar to Telnet, is ssh. SSH can be thought simply as secure telnet. It runs on port 22.
FTP: ftp stands for
File Transfer Protocol. File transfer provides a means for you to obtain
computer files (text, image, sound, etc.) from other computers over
the network. ftp can also be used to send (upload) files from your computer
to another computer, providing you have write permission or a real account
on the machine you are uploading. FTP runs on TCP/IP port 21 .
Ping: The ping command
sends an echo request to a network host. It is useful for determining
the status of the network and various foreign hosts. The ping command
sends one datagram per second and prints one line of output for every
response received. Round-trip times and packet loss statistics are calculated
and displayed. Ping uses the ICMP protocol. This is an IP protocol,
so it does not have a port number.
Traceroute: Traceroute
is a utility that records the route (the specific gateway computers
at each hop) through the Internet between your computer and a specified
destination computer. It also calculates and displays the amount of
time each hop took. Traceroute also uses the ICMP protocol.
Let's practice a bit:
- Telnet into your ctssn.com account
- Now, type in "ftp
ctssn.com" from your home directory.
- You should be given a log in prompt. Please enter your ctssn.com username and "ftptry" for the password. Oops, that is the wrong password. Type in "user" to get another log in prompt. The correct username is "anonymous" and the password will be an email address. You will be prompted for
this. What you have just done is start an anonymous ftp session.
- Type "ls -al"
to get a listing of files. Does this look familiar?
- Type "cd /public_html"
to put yourself into the pub/public_html directory on the remote anonymous
ftp server. Again do an "ls -al" . What do you see?
- Now we are going to grab
one of those files. Type in "get lesson4.html" and press
return.
- Now type "quit".
- You should be back at
your UNIX prompt. Type "ls" to see a listing of files in
your directory. Do you see the file you pulled off the remote server?
- Now, copy lesson4.html
file to a new file named something unique, like your name. Do this
by using the "cp lesson4.html newFile.html" where
newFile.html is the name you have chosen for the file. (it
is important to pick a unique name)
- FTP back into the ctssn.com
and type "cd incoming"
- Now type "put newFile.html" where newFile.html is the name of the file you made in the previous steps. This should send the file back to the remote server. Type ls -al to see that it worked.
- Type "help" to get a listing of commands to use. Type "help commandname" to get information on a particular command.
- Type quit to exit the
ftp program.
- Now type "ping yahoo.com"
You should start to see ping responses. Type <control c> to
stop the program. How is our connection to yahoo? (ping is not enabled on ctssn.com It does work at a DOS prompt in a similar fashion)
- Type in "ping -c
10 yahoo.com" Wait until the program stops itself. What happened
differently this time?
- Now type in 'traceroute
yahoo.com" . What happens? Now type in "whereis traceroute"? What does it say?
