In the Defensive Computing blog at Computerworld Michael Horowitz updates us on the fate of Barry Ardolf. Barry was the genius who hacked his neighbors wifi network then proceeded to try to frame them with crimes ranging from child pornography to death threats on Vice President Biden. He was sentenced to 18 years in prison for his efforts.
Barry was able to hack his neighbors wifi because the neighbor used the totally cracked WEP encryption. With the proper software you can crack a WEP network in well under a minute. WPA has the same problem if you don't use strong passwords.
If Barry Ardolf had been a little smarter he might have actually gotten away with framing his neighbor as he'd planned. All because the neighbor used the weakest encryption on his network. Sort of like using 1/8" balsa wood for the door of a bank vault. Sometimes you don't have any choice because of legacy equipment, but you should always use the strongest encryption available. A WEP encrypted network almost got an innocent man implicated in child pornograghy and threatening the vice president.
There are a lot of different routers, and setting the security is different on all of them. The fastes way to learn how to setup the security on your router is to go to the manufacturers website and download the manual.