Abstract: An IEEE 802.11 security system for monitoring wireless networks with a view to detecting and locating unauthorized or threatening IEEE 802.11 devices entering a user's wireless network environment or a facility not intended to support wireless networks is disclosed. The security system comprises a network appliance subsystem and a portable computing subsystem with data means to interface between the two systems. Optionally, counter-measuring means for launching neutralizing and/or disabling counter-measures against a suspected device upon activation can be incorporated into the security system. A method of operation of the IEEE 802.11 security system is also disclosed.