Hardware Selection

The most important choice you'll need to make is which wireless adapter to use. In our original tutorial, we had to choose a WLAN adapter that was supported by the assortment of tools involved in the crack. At the time, that meant cards using the PRISM chipset.

Today, however, the PRISM chipset isn't commonly used in consumer wireless LAN adapters, so isn't a good choice. And since we're going to use only one tool suite, you'll have to deal with only one hardware compatibility list. The result is that you can use a variety of wireless adpaters for your WEP cracking attempts.

NOTE: At this time, there are no drivers to support draft 802.11n wireless chipsets or adapters. Your choices in cards are limited to those supporting 802.11 a, b and g standards.

Fortunately, the aircrack-ng site has plenty of help and advice for choosing a suitable wireless adapter. Their recommendation, however, is to use a card with the Atheros chipset. Of course, we didn't follow their advice at first and suffered the consequences.

Tim first tried the Intel PRO/Wireless 2915ABG mini-PCI adapter embedded in one of his notebooks. It was recognized by BT2 and was able to be put into monitor mode for packet capture and could even inject packets for the ARP replay attack used to generate traffic. But it was able to capture packets only at a very low rate, true to the note in the above Aircrack hardware compatibility page. The upshot was that WEP cracking was possible, but way too slow, especially for WEP 128.

Kevin took another route, using an Edimax EW-7318USG USB adapter. He was successful in using it, but had to perform some workarounds in BT2, which are described in Appendix 2.

In the end, we took the Aircrack team's advice and used a mini-PCI card with an Atheros AR5212 a/b/g chipset embedded in another notebook. Although the Aircrack page mentions the need for patched drivers for Linux aireplay support, we had no problems using the drivers that came with the BackTrack 2 Stable Mar 06 2007 (bt2final) release.

Tags: Hacking, How To, WEP, WiFi,

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