Friday, March 29, 2019

Recovering root user password in CentOS or RHEL 7

What if you forget root user password? 

RHEL/CentOS 7 has a way to recover root user password, but this will need downtime of your linux host.

To recover your root user password follow below procedure as shown in screenshots:

Step 1 :  Reboot host, come to GRUB screen and select Kernel without "rescue" option:


PRESS "e"

Step 2 :  Scroll your cursor down till you see line starting from "linux16".  Come  to the end of line after "UTF-8" give a space and write "rd.break":



PRESS "CTRL + x", this will interrupt the boot process and leave you to the shell prompt :



Step 3 : Once you come to shell prompt, remount "/sysroot" with "rw" permission i.e. read/write and then chroot to "/sysroot" directory:


# mount -o remount,rw /sysroot/
# chroot /sysroot/

Step 4 :  Now we can go ahead and reset "root" user password using "passwd" command:


Step 5 : Once new root password is set and SELinux is ENABLED then create "/.autorelabel" file using touch command, so that it will relabel shadow file:

# touch /.autorelabel

Press "Exit"
Press "Exit"

This will reboot system and once it comes up, you would be able to login as root user with new password.


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