From 69c3a754d8e81bd71821efbc03da5b5a6a91d885 Mon Sep 17 00:00:00 2001 From: Ben Burwell Date: Sat, 28 Mar 2015 13:25:11 -0400 Subject: Added resetting lost password post --- ...tten-password-on-luks-encrypted-ubuntu.markdown | 34 ++++++++++++++++++++++ 1 file changed, 34 insertions(+) create mode 100644 _posts/2015-03-28-reset-forgotten-password-on-luks-encrypted-ubuntu.markdown (limited to '_posts') diff --git a/_posts/2015-03-28-reset-forgotten-password-on-luks-encrypted-ubuntu.markdown b/_posts/2015-03-28-reset-forgotten-password-on-luks-encrypted-ubuntu.markdown new file mode 100644 index 0000000..1c30045 --- /dev/null +++ b/_posts/2015-03-28-reset-forgotten-password-on-luks-encrypted-ubuntu.markdown @@ -0,0 +1,34 @@ +--- +title: How to Reset a Lost Password on a LUKS-Encrypted Disk in Ubuntu Linux +description: I recently needed to reset a lost password on an Ubuntu installation. But the LUKS encryption on the disk gave me some challenges. Here's what I did. +layout: post +category: writing +date: 2015-03-28 00:00:00 +--- + +Here's the situation I recently found myself in: + +* Ubuntu Linux 14.10 +* Unknown password for user account +* Unknown (but set) root password (Ubuntu's philosophy is to use `sudo` for everything) +* LUKS encrypted filesystem (known passphrase) +* Physical access to the computer + +I needed to reset my account password. Normally, with physical access to a machine, all bets are off when it comes to security. I tried booting up the machine into [recovery mode](https://wiki.ubuntu.com/RecoveryMode) by holding down shift as soon as the BIOS had finished loading. But when I selected the "Drop to root shell" option, I was prompted to enter the unknown root password. + +My second approach was to boot into single user mode by editing the GRUB command script. + +
Ubuntu's GRUB menu
+ +By going down to the recovery mode option and hitting e, you can edit the GRUB commands. By adding init=/bin/bash at the end of the line beginning with linux that specifies the boot image, you can specify an initial shell to use. Then I hit F10 to boot. + +After waiting for about 30 seconds or a minute, I saw a message that waiting for the root device (the locked disk) had timed out. I was then dumped into an [initramfs](https://wiki.ubuntu.com/Initramfs) shell. From there, I was able to unlock the disk by running cryptsetup luksOpen /dev/sda3 sda3_crypt. + +Next, I mounted the freshly-unlocked disk with mount -o rw /dev/sda3 /root, taking advantage of the pre-existing empty directory. From there, I used chroot to run passwd in the OS. + + $ chroot /root passwd + $ chroot /root passwd myUserName + +By running these commands, I successfully reset both the root password as well as the password for my account. From there, I was able to restart the machine and boot normally. + +*Is something here incorrect? Know of a better way to do it? Let me know [@bburwell](https://twitter.com/bburwell).* -- cgit v1.2.3