Used to be called 'noise' in the good old days. Now it is often seen as harrasment or something equaly evil.

Fact is XP machines still contain the dogged old networking utils that display who and/or what is connec/ing/ed to a computer, and you can turn on the firewall, but I would not bother if you are behind a newish router.

The basic extra net command is 'netstat -an. The local is slighly more exotic but just as effective 'nbtstat'. Sure there are skipt kiddies out there smart enough to find a workaround, but hey not every machine is configured in the same generic way, AND lots of them have updated and/or encrypted BIOS - decrypt that for what? Some old geezer in the Garage venting about the price of dogfood? Naw.. Mostly the assebler savy homemade HL kid is not even slightly interested in finding out where you keep your system files.

More often they like to break into corporate networks to steal something usefull..

Your'e not hacked, your networking files are old or badly configured or your on a Cable network that is too noisey...