IP changeover

[Julio]

today I had a static ip changeover from Oceanic and when they were resetting
my modem the representative  told me that they could see how many computers
I have behind my router, now is is posible to block them out of my internal
network?
can this be done with linux?
also now I'm using win2k for a router but I've been in the process of
changing it to a linux router /firewall but have been having lots of
problems configuring NICs .
and last, is it legal for oceanic to do port scans or to go into my internal
network ?  How can I keep them out?

Thanks!!

Julio

If you can't beat your computer at chess, try kickboxing!