Wireless Intruder Alert Systems
Something I'm surprised I don't get more questions about is how to tell when someone (who you don't want there) is trying to use your wireless LAN. I swear there used to be a simple application that came with early Macintoshes called "Knock Knock" that would pop up a dialog when someone attempted to connect to your Mac. I'm looking for something similar, preferably free, that runs on Windows.