Recover / Reset root Password in Rescue

In previous articles Recovering the Root Password (RHEL / CentOS 7) and Recovering the Root Password (Ubuntu) was how to Recover / Reset root Password from the Kernel.

In this guide, we will provide Information how to Recover / Reset root Password for any Server (Cloud, Dedicated) in Rescue mode.

Boot your Server into Rescue; if your Server is Cloud Server or Cloud VPS, we would recommend use Knoppix. If your Server is Dedicated, then just reboot Server with the available Rescue option you have.

1- Recover root Password (Cloud Server, Dynamic Cloud Server)

After booting your Server into Rescue using Knoppix, you need to access your Server with the provided Emulator (KVM, VNC)

First, switch to root user, “this is not your Server root, it’s Knoppix root user”:

# sudo su -

Then, either to activate the SSH Service in order to use your SSH Client (MobaXterm, Putty), or you can proceed with the steps from (KVM, VNC).

If you would like to use your SSH Client, then you need to set password for Knoppix root user, after that you can access your Server using your SSH Client:

# passwd root

Please refer to How to mount Cloud / VPS Cloud in Rescue to Activate your Logical Volume and mount to /mnt Directory.

After mounting your Logical Volume to /mnt Directory, you need to mount the following system files:

# mount --bind /dev /mnt/dev
# mount --bind /dev/pts /mnt/dev/pts
# mount --bind /proc /mnt/proc
# mount --bind /sys /mnt/sys

Then, chroot /mnt, once you chroot /mnt, you are can then proceed as if you were working with your usual server configuration.

# chroot /mnt

Then proceed with changing your root Password:

# passwd
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Then exit chroot, and unmount file systems, then reboot Server:

# exit
# umount -a
# reboot

Eject Knoppix DVD, and now you can access your Server using your new Password.

2- Recover root Password on other Servers

– Dedicated Servers

After booting your Server into Rescue, access your Server either via Serial Console, or normal SSH, then you need to check your Server Disks and Partitions with fdisk command:

# fdisk -l

Disk /dev/sdb: 1000.2 GB, 1000204886016 bytes, 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x76a7d556

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1            2048     8390655     4194304   fd  Linux raid autodetect
/dev/sdb2         8390656    12584959     2097152   82  Linux swap / Solaris
/dev/sdb3        12584960  1953525167   970470104   fd  Linux raid autodetect

Disk /dev/sda: 1000.2 GB, 1000204886016 bytes, 1953525168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk label type: dos
Disk identifier: 0x76a7d556

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048     8390655     4194304   fd  Linux raid autodetect
/dev/sda2         8390656    12584959     2097152   82  Linux swap / Solaris
/dev/sda3        12584960  1953525167   970470104   fd  Linux raid autodetect

Disk /dev/md3: 993.8 GB, 993761296384 bytes, 1940940032 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/md1: 4294 MB, 4294901760 bytes, 8388480 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/vg00-usr: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/vg00-var: 112.7 GB, 112742891520 bytes, 220200960 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/vg00-home: 5368 MB, 5368709120 bytes, 10485760 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

With having /dev/md1 and /dev/md3 then, you need check your RAID in order to determine which drive has sda1:

# cat /proc/mdstat
Personalities : [raid1]
md1 : active raid1 sdb1[1] sda1[0]
      4194240 blocks [2/2] [UU]

md3 : active raid1 sdb3[1] sda3[0]
      970470016 blocks [2/2] [UU]

So, we mount /dev/md1, because it contains the file system we need:

# mount /dev/md1 /mnt
# mount /dev/mapper/vg00-var /mnt/var
# mount /dev/mapper/vg00-usr /mnt/usr
# mount /dev/mapper/vg00-home /mnt/home
# mount --bind /dev /mnt/dev
# mount --bind /dev/pts /mnt/dev/pts
# mount --bind /proc /mnt/proc
# mount --bind /sys /mnt/sys

Then, chroot /mnt, once you chroot /mnt, you are can then proceed as if you were working with your usual server configuration.

# chroot /mnt

Then proceed with changing your root Password:

# passwd
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully

Then exit chroot, and unmount file systems, then reboot Server:

# exit
# umount -a
# reboot

Boot your Server back to Local, and now you can access your Server using your new Password.