NetStumbler (also known as Network Stumbler) is a tool for Windows that facilitates detection of Wireless LANs using the 802.11b, 802.11a and 802.11g WLAN standards. It runs on Microsoft Windows 98 and above. A trimmed-down version called MiniStumbler is available for Windows CE.
NetStumbler is commonly used for: Wardriving, verifying network configurations, finding locations with poor coverage in one’s WLAN, detecting causes of wireless interference, detecting unauthorized (”rogue”) access points, aiming directional antennas for long-haul WLAN links