spiralofhope

Linux + Security >

was https://www.serverwatch.com/tutorials/article.php/3818511

Juliet Kemp

Sometimes you wind up taking over a machine for which the root password has been lost. Here are a couple of solutions.

• Reboot (hard reboot by pulling the power cable if rebooting requires the root password), and hit e to edit the boot line when you get to the GRUB menu. Scroll down to the line that starts with kernel, then hit e again to edit it, add 'single' to the end, and hit Enter to accept. Now b to boot and eventually you'll be dumped into a root shell. From here type passwd to change the root password.

  • [from me]: Don't ever pull the power cord on your computer! Hold the power button down for four seconds, or find a switch at the back of your case at the power supply. If all else fails, turn your power bar switch off. You do use a surge-protecting power bar or UPS for your computer, right?

• Some systems require the root password to boot into 'single' mode. In this case, try editing the grub boot line to add init=/bin/bash to the end of the kernel line. This will boot you into a very basic system, using the bash shell instead of init. You may have to mount the root partition read/write:

mount -no remount,rw /

Then use passwd to reset the password.

• If grub is protected, try booting from a LiveCD or USB stick. Open a root shell, and use fdisk -l to show the available disk partitions. Mount the root partition with

mount -o,rw /dev/hda1 /mnt

Check it's the right directory with ls /mnt, then change into that as your root directory:

chroot /mnt

Now use passwd as before.

NOTE: It's important to bear in mind that all of these are also potential security risks if people have physical access to your machines.

Last updated 2020-10-12 at 00:32:16