In Backtrack5, there’s an easy way to have a new MAC address upon every bootup for your network devices.
System > Startup Applications > Add
Name – anything
Command – macchanger -r eth0
Comment – anything
That’s it. Add another for your wlan0 device. The application ‘macchanger’ is installed by default, and the -r option is for random MAC address. Tested and working on BackTrack 5 R2.
Another method is creating a startup script.
Create a script ‘automac.sh’
sudo ifconfig eth0 down
macchanger -r eth0
sudo ifconfig eth0 up
sudo ifconfig wlan0 down
macchanger -r wlan0
sudo ifconfig wlan0 up
Copy the script into /etc/init.d
Run the following commands
sudo update-rc.d automac.sh defaults
sudo chmod +x /etc/init.d/automac.sh
Now it will run on startup, and randomize the MAC address for your eth0 and wlan0. This was tested on Blackbuntu.