I posted an item last year about these "WiFi WarDrivers" but the whole WiFi thing has expanded so much I need to do it again. The idea in brief, is that once one sets up the WiFi, as I did for example, to allow me to sit on my backporch and work on Internet things, one needs to address WEP or other kinds of security and encryption. I was shocked to find that my next door neighbor had a WiFi network as well as I did. And guess what? When mine isn't on, I can use his, as he doesn't have any encryption. The war chalking thing is to locate nodes and use symbols on buildings, as in "M..." where

One beggar pretends to trip, and slaps a M in chalk on Beckert's back, as he stands in front of a fruit stand, using the knife he kills children with, to cut an orange for another potential victim.

The mark alerts the cognescenti to the kind of encryption and port that is available. My Auntie Hildur's mother believed in giving hungry men sandwiches during the Depression, and her house was "hobo chalked" to indicate "no dog, sandwiches." That is one of the connections that caught me about the warchalking/wardriving idea. Don't leave file sharing on, use WEP encryption, those are a couple of pointers. Good luck, and try WiFi--it is worth taking a few precautions for.