Ran across this interesting piece in Slate by Paul Boutin on how anyone can hack into someone else's WiFi access. At first glance, you would think this is an irresponsible thing for Boutin to write about, but after reading it closely, you'll see that his point of view is more along the lines of if you learn how to "steal" WiFi, you'll have a better understanding of how to secure your own wireless network from hack attacks.

In addition, the piece talks about a practice that I never heard before called "warchalking", a method whereby hackers would write symbols in public places to alert others as to the location of nearby wireless access points.

If you want to find a Wi-Fi network, don’t start by looking on the sidewalk for chalk marks. “Warchalking,” a technique for writing symbols in public places to alert neighbors to nearby wireless access points, is a cool concept that’s been undermined by the fact that no one has ever used it. The best method to find some free wireless is to treat your laptop like a cell phone. Since Wi-Fi and cell phone signals travel on a similar radio frequency, the same tricks you use for getting a better phone connection might work on your computer. Sit near a window,  since Wi-Fi signals travel better through glass than through solid walls. Stay away from metal objects. Pay close attention to your laptop’s orientation—rotating your machine just a few degrees could help you pick up a network that you couldn’t see before. Raise your laptop over your head, put it flat on the floor, tilt it sideways while leaning halfway out the window—get out the divining rod if you have to. You might get a reputation for being some sick laptop yoga freak, but isn’t free Internet worth it?

If you live downtown or in a suburb where the houses are close together, a few minutes of laptop gymnastics will probably reveal several Wi-Fi networks. Certain names are a giveaway that a network probably won’t be password-protected.

Look for “linksys,” “default,” “Wireless,” “NETGEAR,” “belkin54g,” and “Apple Network 0273df.” These are the default network names for the most popular wireless routers. If a network owner hasn’t taken the time to change the default name, that’s a good clue that they probably won’t have a password either. You should also look for signs of hacker culture. Since hackers love giving away Net access, an all-lowercase name like “hackdojo” is most likely an invitation to log on. On the other hand, a name in all caps is typically a network under corporate lockdown.

If you do get prompted for a password, try “public”—that’s the default on many of Apple’s AirPort units. You can also try common passwords like “admin,” “password,” and “1234”—or just check out this exhaustive list of default passwords. You should also try using the name of the network in the password space. A generic password could mean that the network’s owner didn’t have the sense to pick something less obvious or that they’ve decided to welcome outsiders. But who cares? You’re in. And again, there’s no specific law barring you from guessing the password, as long as you don’t crack an encrypted network and read other people’s transmissions.