Scanning a Subnet with python?

[Axel]

Hi,
I want to scan a subnet with python, but I don't know how?
What I want to do:
I want to write a chat program in pure python(with a Tkinter gui). It should
include both client and server, so that the first user opens a server and
all other connect to this server. Further, the program should be OS
independent.

My problem:
I want to give the user possiblity to scan the subnet wheter there is a
server
or not, but how can I perform such a test?

If I get the subnet mask, I will test every IP wheter the computer is up and
wheter there is a runnig server on it, but how can I get the subnet mask
using python?
Or, does anyone know a better way to scan a subnet with python?


Thanx,
Axel

Python comes with batteries included,
but does it have an otto-motor too?