Root Password Reset

The prgmr.com rescue image can be used to reset the root password for the vps similar to a rescue disk like tomsrtbt or the debian installer rescue mode. If you run netbsd, you can also boot the netbsd installer from the rescue disk for a similar process.

1. If the vps (domU or domain) is still running, shut it down with the menu on the host server (dom0).

   Name                                        ID   Mem VCPUs      State   Time(s)
   build                                      447  1024     1     -b----     16.6
   
   Options for build
   1. console
   2. create/start
   3. shutdown
   4. destroy/hard shutdown
   5. reboot
   6. exit
   press the number> 3
   </li>
   

   This will signal the domain to safely shutdown like the shutdown command.
2. When it is stopped running, opening the menu will say

   Error: Domain 'build' does not exist.
   

   which is normal, it just means the vps isn't running. Choose create to start the vps:

   
   Error: Domain 'build' does not exist.                                     
                                                                             
                                                                             
   Options for build                                                         
   1. console                                                                
   2. create/start                                                           
   3. shutdown                                                               
   4. destroy/hard shutdown                                                  
   5. reboot                                                                 
   6. exit                                                                   
   press the number> 2     
   

   The vps will start booting with pvgrub and will load the grub menu from the rescue image:

       
       GNU GRUB  version 0.97  (1048576K lower / 0K upper memory)
    
    +-------------------------------------------------------------------------+
    | user domU bootloader                                                    |
    | CentOS rescue (2.6.18-164.6.1.el5xen)                                   |
    | CentOS 5.4 installer                                                    |
    | NetBSD 5.0.1 installer                                                  |
    |                                                                         |
    |                                                                         |
    |                                                                         |
    |                                                                         |
    |                                                                         |
    |                                                                         |
    |                                                                         |
    |                                                                         |
    +-------------------------------------------------------------------------+
       Use the ^ and v keys to select which entry is highlighted.
       Press enter to boot the selected OS, 'e' to edit the
       commands before booting, or 'c' for a command-line.
   

3. Choose CentOS rescue to boot the read only rescue image. When it is finished booting, login as root at the prompt with no password:

   CentOS release 5.4 (Final)
   Kernel 2.6.18-164.6.1.el5xen on an x86_64
   
   build.xen.prgmr.com login: root
   [root@build ~]#
   

4. Mount your root filesystem (by default /dev/xvda1) and chroot to it:

   [root@build ~]# mount /dev/xvda1 /mnt
   [root@build ~]# chroot /mnt
   build:/#
   

5. Change the root password with passwd:

   build:/# passwd
   Enter new UNIX password: 
   Retype new UNIX password: 
   passwd: password updated successfully
   build:/#
   

6. Exit, unmount, and shutdown:

   build:/# exit
   exit
   [root@build ~]# umount /mnt
   [root@build ~]# shutdown -h now
   
   Broadcast message from root (xvc0) (Tue Jan 26 15:33:15 2010):
   
   The system is going down for system halt NOW!
   INIT: Switching to runlevel: 0
   INIT: Sending processes the TERM signal
   

7. Start the vps again as in step 2.