Changing a forgotten root password on an ESX host

Note: In some cases a defective keyboard can cause problems logging into an ESX host. You might want to test with a different physical keyboard if you are having difficulties with known login credentials.

 

If you have forgotten or do not know the password for the root user on an ESX host, you may be able to change it without reinstalling. 

 

Warning: This can be used maliciously and should be safeguarded against through proper physical access to the host, authenticated remote console access, monitoring and protection against reboot procedures (e.g. grub password) and limited access to the management network.

 

For more information on security best practices, see http://www.vmware.com/resources/techresources/726.

 

Note: The procedure(s) below perform a password reset. This "blindly" replaces the existing root password with a new one. This is not a password recovery mechanism. That is, it does not allow you to learn the original root password. VMware does not provide tools or methods to recover the original root password of an ESX

1. Shutdown and Reboot your VMware ESX Server

If you don't know the VMware ESX Server root password, you don't know any passwords for root-equivalent accounts, and your virtual center server also does not have it cached, the only way to change the root user password is to first shutdown / power off your VMware ESX Server.

2. Press "a" to modify the kernel arguments

As soon as you see the GRUB boot screen, press "a" to modify the kernel arguments, like this:

3. Enter single user mode

At the end of the kernel arguments command line, type "single" and press Enter, like this:

4. Change the root password

Now, change the root password using the passwd command, like this:

You will need to enter the new root password twice.

5. Reboot the ESX Server

Once you have reset the root password, reboot the server to go back into multi-user mode.

6. Verify the new password

Once the system reboots, verify that the new root password works, like this:

In Summary

Resetting the VMware ESX Server root password is not difficult but you will have to bring down the server, enter single user mode, use the passwd command, and reboot to get the task completed.