How to change a root password of a root user for a KVM VM via CLI in SolusVM?

Question

How to change a root password of a root user for a KVM VM via CLI in SolusVM?

Answer

It should be done using the Linux native KVM functionality:

1. Stop a VPS:
   # virsh destroy kvmid
2. Find the location of its storage:
   # virsh domblklist kvmid
3. Mount the storage:
   # guestmount  -a PATH -i --rw /mnt_tmp/
4. Create hash of a new password:
   # openssl passwd -6 -salt AbCdEfGh mypassword
5. Change permissions of shadow file in a mounted directory:
   # chmod 755 /mnt_tmp/etc/shadow
6. Open shadow file with a text editor and replace a value of an existing password ( between first and second colons; <password> in my example below):
   root:<password>:0:99999:7:::
7. Save changes and remove permissions from shadow file:
   # chmod 000 /mnt_tmp/etc/shadow
8. Unmount the storage:
   # umount /mnt_tmp/
9. Boot the VPS and confirm that the password has changed:
   # virsh start kvmid

Note: Replace kvmid respectively.

Note: Mounting directory /mnt_tmp/ is given as an example. Another mounting point could be used. Make sure it exists prior mounting.

Note: PATH is the path to a storage from the step 2. mypassword- is your new password

Note: A value after -salt (AbCdEfGh in this example) will define how secure the encryption will be. Make sure you define different values each time you manually changing a password.

For more information use the official RedHat documentation