INT21CN Computer Networks
Practical #11
- Discover the IP address of the computer you're using to read this Prac
sheet. How you do this depends on what operating system you're running.
- On MS Windows, the only (built-in) way that I know of is to start up a
"Command Prompt" (the thing that used to be called a DOS Window) and type
the command
ipconfig
, or
ipconfig /all
if you want to know
everything. There are lots of freebie GUI apps that Windows users
can download that will tell them the same information -- most net-based
gamers do this sort of thing all the time!
- on a MacOS (9.2 and earlier) system you can simply look at the "TCP/IP"
Control Panel. On MacOS X, the information is in the "Network" option of the
System Preferences utility. The
ifconfig
works as well
in a terminal window, see next bullet point.
- The generic Unix command for this is
ifconfig -a
. This lists IP addresses, and lots
more, for all network interfaces on the machine. NB: this
command doesn't work on the SGI systems. Instead, you have to specify
which interface you want to know about. Typically we use
ifconfig ef0
to find out about interface
ef0
.
What is the (apparent) class of the IP
address that you discover? What is the netmask in use? Are
there any other IP addresses mentioned that are interesting? And anyway, why
did I use the word "apparent" above?
- Optional Exercise: write [1]
a computer program that can translate between 32-bit numbers and dotted
decimal form. Extend your program to determine whether the address is class A,
B or C, and print the network and host portions. Further extend your program
to recognise and identify special IP addresses such as the limited broadcast
address, a directed broadcast address, etc.
Copyright © 2004 by Philip
Scott, La Trobe University.