Photos: Hacking at Defcon

A baseball cap for sale says "I read your email."

At a hacker convention, it might even be true. The "Wall of Sheep" is a Defcon project that sniffs out passwords and login data that are traveling over wireless connections. If it finds a password, it'll display the owrd on a screen (obfuscating it just a little). Attendees are encouraged to use a wired connection instead--and encrypt everything, just in case.

Photo by Declan McCullagh/CNET News.com