Here’s a video showing you how to crack Wireless WEP keys using Backtrack 4 and aircrack-ng.
Additionally, you need a compatible wireless adapter or compatible wireless chipset which can be used with aircrack-ng.
Here are the list of the best wireless cards to use(according to aircrack-ng wiki):
- Alfa AWUS036H [b/g USB] 1W 802.11b/g USB Wireless WiFi Network Adapter
- Ubiquiti SRC 802.11a/b/g PCMCIA Cardbus
- Cisco Aironet 350 Adapter ( AIR-PCM352 )
Good luck!
please review feedingbottle. a gui app for aircrack. worth trying.