Recover the Root Password in RHEL 7

If you boot a RHEL 7 system into the rescue or emergency target, you are prompted for the root password. But what if you have forgotten the password? This exercise shows the steps required to reset a lost password for the root user. During the password-recovery process, you probably won’t have access to documentation. Hence, you should practice the following procedure until you can use it in a crisis:

1. Reboot the server.
2. When you see the following message, press a key to access the GRUB menu:
3.  Press E to edit the current menu entry.
4. Scroll down with the DOWN ARROW key to locate the line starting with linux16. Press CTRL-E or END to move to the end of the line, and then type the string rd.break.
5. Press CTRL-X to boot the system.
6. The rd.break directive interrupts the boot sequence before the root filesystem is properly mounted. Confirm this by running ls /sysroot. If you know the contents of the root filesystem, the output should look familiar.
7. Remount the root /sysroot filesystem as read-write and change the root directory to /sysroot:

• Reset password using passwd command. This is possible even if you booted from rescue disk. The idea is to use chroot command. Once you're at a command prompt, mount the system's root directory if it's not already mounted:

  mount -o remount,rw /sysroot

  Now, execute chroot command. After that you can reset the password:

  chroot /sysroot
  passwd

10.  Change the root password:

11.  Because SELinux is not running, the passwd command does not preserve the context of the /etc/passwd file. To ensure that the /etc/passwd file is labeled with the correct SELinux context, instruct Linux to relabel all files at the next boot with the following command:

touch /.autorelabel 

12.  Type exit to close the chroot jail, and then type exit again to reboot the system.

13.  It may take a few minutes for SELinux to relabel all files. Once you get a login prompt, confirm that you are able to log in as the root user.