Network detectors or network discovery software are computer programs that facilitate detection of wireless LAN

Wireless LAN

A wireless local area network links two or more devices using some wireless distribution method , and usually providing a connection through an access point to the wider internet. This gives users the mobility to move around within a local coverage area and still be connected to the network...

s using the 802.11b, 802.11a and 802.11g WLAN standards. Discovering networks may be done through active as well as passive scanning.

Active scanning

Active scanning is done through sending multiple probe requests and recording the probe responses. The probe response received normally contains BSSID and WLAN SSID. If SSID broadcasting has been turned off however, and active scanning is the only type of scanning supported by the software, no networks will show up. An example of an active scanner is Network Stumbler

NetStumbler

NetStumbler 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 operating systems from Windows 2000 to Windows XP...

.

Passive scanning

Passive scanning is not done by active probing, but by mere listening to any data sent out by the AP. Once a legitimate user connects to the AP, the AP will eventually sent out a SSID in cleartext. By impersonating this AP by automatic altering of the MAC address, the computer running the network discovery scanner will be given this SSID by legitimate users. Passive scanners include Kismet and essid jack (a program under AirJack

Airjack

Airjack may refer to:* Aircraft hijacking* Airjack...

).

Notable programs

Notable programs include Network Stumbler, Kismet, Aerosol

Aerosol

Technically, an aerosol is a suspension of fine solid particles or liquid droplets in a gas. Examples are clouds, and air pollution such as smog and smoke. In general conversation, aerosol usually refers to an aerosol spray can or the output of such a can...

, AirMagnet

AirMagnet

AirMagnet is a Wi-Fi wireless network assurance startup based in Sunnyvale, California. The firm was founded in 2001 by Dean T. Au, Chia-Chee Kuan and Miles Wu and shipped its first WLAN analyzer product in 2002. In August 2006, the company shipped the Vo-Fi Analyzer, the first voice-over-Wi-Fi...

, MacStumbler, Ministumbler, Mognet, NetChaser, perlskan, Wireless Security Auditor, Wlandump, PocketWarrior, pocketWinc, Prismstumbler, Sniff-em, AiroPeek, Airscanner, AP Scanner, AP Radar, Apsniff, BSD-Airtools, dstumbler, gtk-scanner, gWireless, iStumbler

IStumbler

iStumbler is an open source utility for finding wireless networks and devices with AirPort- or Bluetooth-enabled Macintosh computers.iStumbler was originally based on MacStumbler source code...

, KisMAC

KisMAC

KisMAC is a wireless network discovery tool for Mac OS X. It has a wide range of features, similar to those of Kismet...

, Sniffer Wireless, THC-Scan, THC-Wardrive, WarGlue, WarKizniz, Wellenreiter, Wi-Scan and WiStumbler.