On Unix machines, ifconfig is the command used to get information about, and set network interfaces.
I have created the start of an ifconfig for Tcl, available from here:
(Look for the Tcl section).
-- davidw 2004-12-20
On Windows, you can get similar information from the ipconfig command.
I would be more than willing to include windows code so that it works on windows too. Don't have a windows system myself.
Have a pfun :)