Loosing the root password - Security & Cryptography

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Hello fello nixers,
This thread is about what to do if you lost your root password.

Context: My friend lost his root password and his current user automatically logs into the system without entering any password, so he doesn't remember this one either.

The solutions I could think of:
  • Boot from a live CD and edit the /etc/passwd to make his default user have root privileges, check validity of the file with pwck, log back in to change the root password, set everything back to normal.
  • Boot from a live CD and edit /etc/shadow to put a hash I'm sure of or an empty one. (I've been looking but couldn't find a tool that generates that password so I'm just going to copy it from another box).
  • Boot from a live CD and change the sudoers file to allow his user to be root without entering a password.
  • This doesn't apply here but for BSDs booting into single user mode allows changing the root password. ( https://www.openbsd.org/faq/faq8.html )

This will only work if the hard disk is not encrypted, and it's not so it's fine.

I have found those too:
This one is a way to boot into single user mode linux by appending to the GRUB line:
ro root=LABEL=/
It then gives you a root shell where you can change the password.


Kind of the same spirit, choosing to boot into a rescue mode and then mounting the file system and changing the password.

There's also a mention to add this line to the grub:
Which I assume will use bash as the init process and thus letting you have full control over the OS (source and here).
Parameters of the linux kernel:
parameter     Description
root=     Root filesystem.
rootflags=     Root filesystem mount options.
ro     Mount root device read-only on boot (default1).
rw     Mount root device read-write on boot.
initrd=     Specify the location of the initial ramdisk.
init=     Run specified binary instead of /sbin/init (symlinked to systemd in Arch) as init process.
init=/bin/sh     Boot to shell.
systemd.unit=     Boot to a specified target.
nomodeset     Disable Kernel mode setting.
zswap.enabled     Enable Zswap.
video=<videosetting>     Override framebuffer video defaults.

Do you have any other tips or suggestions?

Here's a bunch of resources on the topic.

Messages In This Thread
Loosing the root password - by venam - 08-09-2016, 12:39 AM
RE: Loosing the root password - by citrus - 08-09-2016, 04:18 AM
RE: Loosing the root password - by venam - 01-02-2018, 05:40 AM
RE: Loosing the root password - by evbo - 01-02-2018, 01:30 PM
RE: Loosing the root password - by xero - 02-02-2018, 01:37 PM