Aircrack-ng is available on the BackTrack LiveCD; it's also available via yum install and source rpm from aircrack-ng.org.
sudo apt-get install aircrack-ng

sudo yum install aircrack-ng (on fedora/CentOs)

How to Crack WPA/WPA2   http://www.aircrack-ng.org/doku.php?id=cracking_wpa  
Ubuntu WEP specific command line example http://www.askstudent.com/hacking/how-to-crack-a-wep-key-using-ubuntu/


This lab shows how to observe, actively bruteforce or passively obtain WPA/WPA2 access keys in an open network.  

WARNING: Key cracking is
considered a breech of private property, do not use this practical
example to connect to public networks as another or without ethical intentions in your own lab networks; this lab is presented
for the purposes of education to ellucidate the limitations of current security tools, and educate users about TRUST.  

Defenses:  Wireless security, is a "trust" model.  Like wired network connections, shared networking presents some risk; i.e. if you can connect, you are sharing packets.  An ICA server/cisco or access point with a changing key is the only defense against these tactics.  The key would change at or around the same time that cracking would take.  Even with WPA keys, Mac Address connection controls are best deployed to provide added security in wireless networks.

www.Obnosis.com |  http://en.wiktionary.org/wiki/Citations:obnosis |
http://www.urbandictionary.com/define.php?term=obnosis (503)754-4452
Catch the January PLUG HackFest!   Kristy Westphal, CSO for the Arizona Department of Economic
Security will provide a one hour
presentation on forensics 1/10/09 at UAT.edu.




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http://clk.atdmt.com/MRT/go/127032869/direct/01/