Introduction

Network Stumbler, also as NetStumbler, is a free program allowing for the detection of all radio WLANs, in given area working , using 802.11a/b/g standards. The program carries active scanning out by sending the sampling signal - Probe Request, in about one second time intervals. At the moment of reply getting from access point- the Network Stumbler defines SSID, the MAC address, the channel which it works, and the level of received signal and accompanying noises. In practice, thanks to such information it is possible :

• checking correctness of configuration for the own net,
• defining area coverage for some network, localization of places which signal level is not enough,
• detection of strange networks causing interference with our net,
• detection of unauthorized access points,
• help with directional antennas visa for long wireless links.