This article will explan how to crack 64bit and 128bit WEP on many WIFI access points and routers using Backtrack, a live linux distribution. Your mileage may very.  The basic theory is that we want to connect to an Access Point using WEP Encryption, but we do not know the key.  We will attack the wifi router, making it generate packets for our cracking effort, finally cracking the WEP key.  I have tested this technique on an IBM Thinkpad x60 and Acer 5672 and the WIFI Chipset in those machines work for sure.

Requirements:

• Backtrack 3 on CD or USB
• Computer with compatible 802.11 wireless card
• Wireless Access point or WIFI Router using WEP encryption

I will assume that you have downloaded and booted into Backtrack 3.   If you haven’t figured that part out, you probably shouldn’t be trying to crack WEP keys.  Once Backtrack is loaded, open a shell and do the following:

Preparing The WIFI Card

First we must enable “Monitor Mode” on the wifi card.  If using the Intel® PRO/Wireless 3945ABG chipset issue the following commands:

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Original link: http://thew0rd.com/2008/08/19/tu...