[howto] Enable/Disable GRUB Password

NOTE: This is not a rock solid secured way of disabling access to your pc. But atleast for those “Windoze users” who have no clue wtf is a grub, it’s going to be pretty effective! I’m going to teach you how to enable as well as disable grub password.

Enable GRUB password:

1. Open terminal and type as root:

# cp /boot/grub/menu.lst /boot/grub/menu.lst.backup

2. Now that your GRUB is backed up. Type:

# grub

grub> md5crypt

Password: ******** [Type in the password that you want to encrypt!]

Now copy the encrypted message it gives you!

grub> quit

3. Open /boot/grub/menu.lst.backup and paste the message after initrd line. If you have a number of Grub entries , you must paste it [or use a different encrypted password using the above method] for every entry that you want to password protect! Use it like this:

title           Debian GNU/Linux, squeeze/sid
root            (hd0,1)
kernel          /boot/vmlinuz-2.6.30-1-amd64 root=/dev/hda2 ro splash quiet vga=791
initrd          /boot/initrd.img-2.6.30-1-amd64

password – -md5 gasgd6876b2dsd2d/

paste the code after “password – -md5”

Note: Since wordpress has the weird habit of showing double hyphen as a single large one, I put a space in between the two, you just need to put two hyphens without any space in between!

Disable/Hack GRUB password:

1. You need a Linux live CD for this.

2. Insert the CD and boot from it.

3. In command line [or if you’re using ubuntu cd 😛 open a terminal and type]:

$ su

# fdisk -l [to check the name of the root directory]

# mount -t ext3 -o rw /dev/sda2 /mnt

[change ext3 to ext4 and /dev/sda2 according o the fdisk -l output]

# chroot /mnt /bin/bash

# nano /boot/grub/menu.lst

Now just remove the password line from the grub menu. 😛 Simple eh? Now save , unmount the partition and reboot!

[howto] Restore Grub

It is always recommended to install Windows first and then Linux, however if you would prefer [for some weird reasons] to do the opposite then follow this guide!

Requirement:

You need a Linux LIVE CD. E.g.-> ubuntu or suse or mandriva,etc etc.

Boot from your Live CD. Now open a terminal and type in:

grub

find /boot/grub/stage1

Now it will show you the correct root partition.

root (hd0,1)   [replace 0 and 1 according to the output!]

setup (hd0)

quit

sudo grub-install /dev/sda [or hda , whichever is your MBR]

reboot

Done!