Thursday, August 28, 2008

Backtrack 3 on the Asus EEE (that rhymes!)

I mentioned a few posts ago about the wonders of the tiny Asus EEE. I’ve just had the latest 901 version delivered with 8 hours battery life and an Intel Atom processor. One of the coolest things I’ve been doing is booting the machine to an alternative OS on an SD card. Perhaps one of the most useful is the ability to boot to the Backtrack distro. It means that you have your tiny portable machine totally ready to carry out sysadmin tasks and even wireless cracking using the inbuilt Atheros wireless chipset.

However getting Backtrack 3 to boot on the EEE has been a problem and a number of forums have questions about it. When you download the bootable USB version (http://www.remote-exploit.org/cgi-bin/fileget?version=bt3-usb) there is a helpful text file telling you which files to copy to the USB key or SD card, then simply browse to the ‘Boot’ folder on the card and run the ./bootinst.sh script. To get a command shell up in the EEE Xandros Linux distro just hold down CTRL-SHIFT-T. Then as if by magic you can boot to Backtrack by simply holding down the ESC key at boot time.

However, a number of people have noted that it seems impossible to run the shell script. You simply get an error message. The solution is very simple. If you look at the permissions for the script (ls -la) you will note that the files on the SD card do not have execute permissions. If you try and change the permissions:-

chmod 777 bootinst.sh

..it pretends to work but another look at ls -la and you see that it hasnt.

The problem is to do with the mount permissions for the device as a whole. If you execute the ‘mount’ command you will see that the device is mounted with the noexec flag set and that is what is messing things up! With no other keys or devices plugged in it seems to always mount at /media/D:, so.. simply unmount the device:-

umount /media/D:

then remount with the following:-

mount -o rw /dev/sdc1 /media/D:

Dropping the noexec flag makes the files executable. Now just browse back to the right directory:-

cd /media/D:/boot

then execute the shell

./bootinst.sh

That’s it, now you can reboot to BT3. Have fun.

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