Lost Password

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The following applies to most linux boxen. It can be used to recover a lost password and is also called "rooting" the box.

Booting into Single User Mode with GRUB

Ubuntu 10.04

Note that after performing step 1 you have a limited time to perform step 2, so please read the instructions fully before beginning the process.

  1. Power on the computer (shut it down first or simply reboot if it is already running).
  2. When the BIOS information or manufacturer's logo "splash" screen appears start holding down the right shift key. If your computer does not usually display BIOS information or a manufacturer's logo you may need to start holding down the shift key immediately after pressing the power button.
  3. After a few seconds you will see the GRUB menu, which is characterized by a lines that will say ...kernel 3.2.... If the system continues to boot normally and arrives at the regular login screen or desktop you will need to restart and try again. If you are repeatedly failing to reach the GRUB menu try quickly and repeatedly tapping the shift key until the menu appears instead of just holding it down.
  4. Hit the down arrow key (usually only once) until it arrives on the first line that ends with recovery mode and press enter.
  5. Select "Root" from the recovery mode menu that appears to enter a shell environment with root privileges.
  6. You should now see a prompt at the bottom of the screen that reads
  root@freekbox:~#

Proceed to "Resetting the Password" section of this page.

Ubuntu 12.04

Note that after performing step 1 you have a limited time to perform step 2, so please read the instructions fully before beginning the process.

  1. Power on the computer (shut it down first or simply reboot if it is already running).
  2. When the BIOS information or manufacturer's logo "splash" screen appears start holding down the right shift key. If your computer does not usually display BIOS information or a manufacturer's logo you may need to start holding down the shift key immediately after pressing the power button.
  3. After a few seconds you will see the GRUB menu, which is characterized by a lines that will say ...kernel 3.2.... If the system continues to boot normally and arrives at the regular login screen or desktop you will need to restart and try again. If you are repeatedly failing to reach the GRUB menu try quickly and repeatedly tapping the shift key until the menu appears instead of just holding it down.
  4. Hit the down arrow key (usually only once) until it arrives on the first line that ends with recovery mode and press enter.
  5. Select "Root" from the recovery mode menu that appears to enter a shell environment with root privileges. Note that until further steps are completed your file system will be in "read only" mode and you will not be able to make any persistent changes to the system.
  6. You should now see a prompt at the bottom of the screen that reads
  root@freekbox:~#

To mount the file system in read/write mode, type in the following command at the prompt; 

  mount -o remount,rw /

Resetting the Password

To reset your password you need to be able to specify the username for which the password is to be changed. Note that the name displayed on your login screen may not be the same as your formal username, instead being a "friendly" name that you provided at some point. For example, if your name on the login screen reads something like "John Doe" then that is almost certainly the "friendly" name, while your formal username is likely to be something more like "jdoe".

To view usernames currently active on the system enter the command 

ls /home

The list that follows (there may only be one or two items if you are the only user of the computer) will indicate all existing home directories, which correspond to users on the system. If you have never changed the default user account on your computer your will probably only see oem.

Once you have identified your username, enter the following command with your specific username substituted: 

 passwd -yourusername-

You will be prompted to enter a new password, then to enter the password a second time to confirm nothing was mistyped.

Once you've updated your password you can restart the system by entering the command 

reboot

After a few seconds your system will reboot. The recovery menu may display again briefly before the computer restarts but will continue to reboot without any input. If you are presented with the GRUB menu again while rebooting then simply press the Enter key to select the first item on the menu and normal startup will continue.

Shadow Folder Method

There are two methods to do this. One which will create a one-time use password for their account which then blanks the password on subsequent logins, and another which will permanently reset their password until you reset it. If the Shorter Way doesn't work, use the Longer Way. Remember to reset their password when you are done!

Also note that if they have a Root Password set you will need to use the #Live CD Method to reset it.

The Shorter Way

This method temporarily replaces the /etc/shadow directory and allows you to reset their password so you can login.

  1. Login via Terminal (alt-ctrl-F2 from GUI login, OR drop into Root Shell via Recovery Mode).
  2. Run :
cp /etc/shadow /etc/shadow.bak.(ISO DATE)

This copies the contents of the Shadow directory to a new directory for backup later. .bak simply reminds you it's a backup, and the ISO Format preserves the date. ISO = Year Month Day. September 24th, 2011 = 20110924.

  1. Run :
passwd (username) -e

This will reset the password of the defined username. The "-e" modifier will expire the defined password after one use. This will result in there being NO password for that account after the defined password expires. Note that this must be run as root. If you have not logged in via root shell you will need to use this code instead : 

sudo passwd (username) -e
  1. Set their password to "freegeek".
  2. Reboot. Their password should have successfully been reset. If you still want to confirm their password has been reset, please follow #Restoring Their Old Shadow Directory.

The Longer Way

This method temporarily replaces the /etc/shadow directory and allows you to reset their password so you can login.

  1. Login via Terminal (alt-ctrl-F2 from GUI login, OR drop into Root Shell via Recovery Mode).
  2. Run :
cp /etc/shadow /etc/shadow.bak.(ISO DATE)

This copies the contents of the Shadow directory to a new directory for backup later. .bak simply reminds you it's a backup, and the ISO Format preserves the date. ISO = Year Month Day. September 24th, 2011 = 20110924.

  1. Run :
passwd (username)

This will prompt for a new password for the designated user name (you can determine their user name from the "whoami" command).

  1. Set their password to "freegeek".
  2. Reboot. Their password should have successfully been reset. You still must reset their password! #Restoring Their Old Shadow Directory.

Restoring Their Old Shadow Directory

  1. Login via Terminal (alt-ctrl-F2 from GUI login, OR drop into Root Shell via Recovery Mode).
  2. Run :
cp /etc/shadow.bak.[ISO DATE] /etc/shadow

This copies the contents of the backed up Shadow directory to the current Shadow Directory. You may need to verify the correct name of the backup by looking in the /etc directory.

  1. Reboot

Live CD method

If the box does not use grub to boot, one can boot the box using a live cd or a System Rescue CD (download one here), then login as root (not necessary with System rescue CD) and proceed by entering the following commands one by one (hit enter after each line). 

mount /dev/sda1 /mnt
chroot /mnt
passwd username    (replace username with the username you're trying to reset, or "oem" if it has not been changed.
sync
reboot

To find your username you can use ls /home

For Macs

For Mac computers at the yaboot prompt enter: 

Linux rw init=/bin/bash

Once you get to the # prompt you will need to reset the terminal 

reset

Now check the username 

ls /home

and reset the users password 

passwd usernamehere

Reset root password

  1. start the computer booting up
  2. After a few (or 10 or 20) seconds you will see a screen that says... Grub Loading...3..2..1.
  3. During this screen, quickly press Esc, to go to the grub menu
  4. Next you will see several lines that start with Ubuntu, kernel 2.6..., this is the GRUB menu.
  5. Select the first line in the list and press 'e'
  6. You should see something along the lines of
root   (hd0,0)
kernel /boot/vmlinuz-2.6.24-27-generic root=UUID=3deb56... ro quiet splash
initrd /boot/initrd.imb-2.6.24-27-generic
quiet
  1. Select the second line and press 'e' again.
  2. Remove 'ro quiet splash' from the end of the line and add 'rw init=/bin/bash'. Hit enter.
  3. Press 'b'. The box will now boot up and you will get a prompt that says 'root@(none):/#'
  4. At the prompt enter
/usr/sbin/usermod -p '!' root

Restart the computer.

Reset Root password CD version

This method involves editing /etc/shadow by hand to get rid of the password.

  1. start the computer and insert the system rescue CD for the password reset.
  2. mount the directory by typing mount /dev/sda1 /mnt
  3. edit /mnt/etc/shadow with vi
  4. remove everything between the first and second colons (:) and replace it with ! (exclaimation mark)
  5. reboot the tower and remove the system rescue cd
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