Kismet – vital Linux wifi security tool
Kismet is a network detector, packet sniffer, and intrusion detection system for 802.11 wireless LANs. Kismet will work with any wireless card which supports raw monitoring mode, and can sniff 802.11a, 802.11b and 802.11g traffic. The program runs under Linux, FreeBSD, NetBSD, OpenBSD, and Mac OS X. The client can also run on Microsoft Windows, although, aside from external drones, there’s only one supported wireless hardware available as packet source.
Kismet is unlike most other wireless network detectors in that it works passively. This means that without sending any loggable packets, it is able to detect the presence of both wireless access points and wireless clients, and associate them with each other.
Kismet also includes basic wireless IDS features such as detecting active wireless sniffing programs including NetStumbler, as well as a number of wireless network attacks.