With hardware selection done, you now need to get some software. As previously mentioned, we are going to be using the popular Back Track 2 Live CD (BT2). (Please be kind and use the Torrent download and consider donating $5 to them.) BT2 is basically a bootable Linux CD based on SLAX. It has everything you need for various security tasks, and writes nothing to your hard drive.
After downloading the ISO file, you have two choices. The first is writing it to CD in the usual way. The second is to put it on a USB thumb drive. To put it on the thumb drive, you need to copy the contents of the ISO to the drive and then run \boot\bootinst.bat. USB is much faster to boot than a CD, and we hoped that any configuration changes would persist. Unfortunately, SLAX is based on a read-only file system and although there is a way to get settings to stick, we couldnt work out how.
Anyway, we digress. Boot from your chosen media and you will be presented with a login screen which helpfully provides the username and password: root and toor. After logging in, type startx to start the GUI. Although all of the aircrack-ng programs are command-line based, you'll need two or three shell windows open simultaneously.
You can even run BackTrack2 on an networked headless system, but unfortunately SSHD (OpenSSH Daemon) isnt enabled in BT2 by default. So the first thing you'll need to do is connect up a monitor, keyboard and mouse to the headless machine and enable SSHD by typing:
setup-sshd; sudo -s
Then you can log in from a Windows computer using PuTTY and the IP address conveniently provided by SSHD.
Step 1 - Check WLAN card
After you log in, first check that your WLAN adapter has been recognized and loaded. This is done by entering iwconfig at the command line. Figure 1 shows what happened on our test system with the Atheros-based card.
Figure 1: iwconfig command output
Write down the name of your device, which in this case is ath0. But yours could be something like wlan1, eth0, wi0, etc.