Use the following steps to set Password in grub, so that only authenticated users have full access of it.
- Make a MD5 encrypted password hash by "grub-md5-crypt" command, Make a note of password hash.
- Now edit GRUB configuration file "/boot/grub/grub.conf" with any text editor, and add a line in to it as below;
- Save file & Reboot your system to check.
- Next, when system reboots go to grub by interrupting boot process (Keep Pressing any key after bios loads), Now once you see grub screen press "P" as instructed there on the GRUB screen, it'll ask you for password.
- Now after entering password, it'll go to unlocked grub screen.