Loading ...How to: Recovering Linux grub boot loader 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 following method/Procedure:
* Use Knoppix cd
* Remove password from Grub configuration file
* Reboot system
* Change 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 system. You need to boot system into single user mode, at boot: prompt type linux single:
boot: linux single
Mount a partition
You need to mount a partition where you grub configuration file is stored. Depend upon Linux distribution the location of Grub configuration file changes. Following list summaries Grub configuration file location:
=> 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 fdisk -l command to obtained partition list.
# fdisk -l
Mount your partition:
# mount /dev/sdb1 /mnt
Remove 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 text editor, locate password line and remove it:
password --md5 $1$9sdflksdf/sdf44k
Save file and reboot the system.
# sync; sync
# cd /
# umount /mnt
# reboot
Change Root password
Now your Grub password removed from system. You need to login to system without password. To restore root user password boot system into 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 following line
init=/bin/shORinit=/bin/bash
4) Press 'b' to boot system
5) Now you are at shell prompt. Just change root password with passwd command:
# passwd
Please note that depend upon your Linux distribution you may need to remount root partition in read/write mode before running above command.
See also:
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You may also be interested in other helpful articles:
- How to: OpenBSD reset root password
- How Do I secure Grub boot loader?
- Configure Ubuntu Linux GRUB to load FreeBSD
- 10 boot time parameters you should know about the Linux kernel
- Best Linux / UNIX Posts of 2007: Part ~ III
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Tags: configuration_file, debian_linux, fdisk_command, fedora_linux, grub_boot_loader, knoppix, linux_distribution, mount_command, passwd_command, password_setup, remove_password, root_password, single_user_mode, suse_linux
If you can’t change the password after booting in single mode , then run the following list of commands:
(In most cases the root filesystem system will be mounted readonly , so we need to remount it)
#mount -t proc proc /proc
#cp /proc/mounts /etc/mtab
#mount -o remount,rw /
give the some instruction