PACKETS
A network simulator by Max Goldstein
http://mgold.github.com/Packets/

In theory, that's any network. Packets is divided into a core and modules. The
core does little more than draw cicles connected with lines and move rectangles
along them. There are ways to extend the core (for example, to model specific
protocols) by subclassing Device, using a different network topology, and
passing functions to configure Device and Link objects. A collection of
extensions is a module (not to be confused with the Python meaning). 

Web is a fairly realistic and somewhat detailed model of internet routing
protocols. Virus is game whose objective is to spread a virus across the
network. The most recent work is in the branch virus-android. 

Each module (and the core) has its own directory. By convention, the file to
execute is called main.py. However, due to the way packages work, it is
necessary to call main from the top level. File with the same names as the
module they run are provided there.

Class hierarchy:

pygame.sprite
    core.Link
        virus.Firewall
    core.Packet
    core.Device
        web.Router
            web.Subnet
            web.DNS
        web.Host
            web.Client
        virus.Computer
        virus.Text