9.9 Using Antennas and WLAN Equipment

Tools used for auditing WLANs include antennas, wireless cards, a portable computer, and specialized software. These tools are legal, readily available, and quite affordable. In most cases, the total cost for a wireless NIC, an antenna, and a pigtail cable is less than $100. The auditing software can be obtained freely from the Internet. This means anyone who has the desire can usually afford the equipment necessary to eavesdrop on an organization's WLAN.

9.9.1 Antennas

Antennas come in many forms. Some are magnetically mounted to the roof of a car, and some are made from Pringles potato chip cans. War drivers often use Orinoco or Cisco pigtail cables and various connectors to locate WLANs. Both omni, strong Yagi, or patch antennas are readily available for such uses. The war driver is able to easily determine network names , WEP usage, and even GPS coordinates of the target wireless devices located. Once a wireless network is found, a directional antenna such as a Yagi can be used to focus the frequency waves (beams) and listen in at great distances. This allows a hacker to operate without trespassing on a victim's property. A directional antenna is also capable of detecting much fainter signals than an omnidirectional antenna and allows the intruder to establish a better-quality link at greater distances.

9.9.2 Wireless Cards

Three very popular NICs are used by hackers to attempt intrusions into WLANs: the Lucent Gold PC Card, the Cisco 350 PC Card, and the Symbol LA-4121 PC Card. They are inexpensive, can be easily obtained, and allow external antennas to be connected using pigtail cables/connectors. Most auditing software supports the chipsets used in these NICs, and each NIC provides site- surveying software that is useful for more than just intrusions and intrusion audits .