Thanks. That is interesting. He's using md5sum to generate random values; setting them to variables and stringing them together to make a random mac.
What could be more interesting, would be to use macchanger to make a valid random mac:
GW=`macchanger -A wlan0`; echo $GW
Current MAC: 00:60:bb:b6:40:11 (Cabletron - Netlink, Inc.)
Faked MAC: 00:dd:00:c7:00:ba (Ungermann-bass Inc.)
My problem is $GW has all that crap in it. I just need GW=00:dd:00:c7:00:ba