How to Recovering Linux Grub Boot Loader Password and Root Password

If you have, a password protected grub boot loader and you forgot both root and grub password, then you can recover grub-boot loader password using the following method/procedure:

• Use Knoppix cd
• Remove the password from Grub configuration file
• Reboot the system
• Change the root password
• Setup new Grub password if required (optional)

Knoppix Live cd

The best way to recovering (or reset) a password (and to solve many other problem) is use Knoppix Live CD. First downloaded knoppix and burn it on CD. Put CD into CD/DVD rom and boot the system. You need to boot system into a single user mode, at boot: prompt type linux single:
 
boot: linux single

Mount Partition

You need to mount a partition where you grub configuration file is stored. Depend upon your Linux distribution the location of Grub configuration file changes. Following list summaries Grub configuration file location for pouplar distros:

• Debian Linux Grub configuration file location: /boot/grub/menu.lst
• Suse Linux Grub configuration file location: /etc/grub.conf
• Red Hat/Fedora Linux Grub configuration file location: /boot/grub/grub.conf

If you forgot partition name use the fdisk -l command to obtained partition list / names:

# fdisk -l

Finally, you need to mount your partition as follows:
 
# mount /dev/sdb1 /mnt 

Remove The Grub Password

a) If you are using Debian Linux you need to modify /boot/grub/menu.lst file: # cd /mnt/boot/grub
# vi menu.lst

b) If you are using Suse Linux you need to modify /etc/grub.conf file # cd /mnt/etc
# vi grub.conf

If you are using Red Hat / Fedora Linux you need to modify /boot/grub/grub.conf file # cd /mnt/boot/grub
# vi grub.conf

Once file opened using a text editor, locate password line and remove it:
 
password --md5 $1$9sdflksdf/sdf44k

Save and close the file. Reboot the system.
 
# sync; sync
# cd /
# umount /mnt
# reboot 
 
Remove CD from cdrom drive and boot from local disk

Change Root password

Now your Grub password is removed from the system. You need to login to the system without any password. To restore root user password boot system into a single user mode.

1) At Grub prompt press 'e' to edit command before booting.

2) Select second line

3) Again, press 'e' to edit selected command

4) Type the following line
 
init=/bin/sh
 
OR
 
init=/bin/bash

4) Press 'b' to boot system.

5) Now you are at shell prompt. Just change root password with the passwd command:
 
# passwd
 
Please note that depend upon your Linux distribution you may need to remount root partition in read/write mode before running the above command.