Kismet is an 802.11 layer2 wireless network detector, sniffer, and intrusion
detection system.  Kismet will work with any wireless card which supports raw
monitoring (rfmon) mode, and can sniff 802.11b, 802.11a, and 802.11g traffic.

Kismet identifies networks by passively collecting packets and detecting
standard named networks, detecting (and given time, decloaking) hidden
networks, and inferring the presence of nonbeaconing networks via data traffic.
