InformationSetting the boot loader password will require that anyone rebooting the system must enter a password before being able to set command line boot parameters
Requiring a boot password upon execution of the boot loader will prevent an unauthorized user from entering boot parameters or changing the boot partition. This prevents users from weakening security (e.g. turning off SELinux at boot time).
SolutionCreate an encrypted password with grub-mkpasswd-pbkdf2:
Enter password: <password>
Reenter password: <password>
Your PBKDF2 is <encrypted-password>
Add the following into /etc/grub.d/00_header or a custom /etc/grub.d configuration file:
password_pbkdf2 <username> <encrypted-password>
If there is a requirement to be able to boot/reboot without entering the password, edit /etc/grub.d/10_linux and add --unrestricted to the line CLASS=
CLASS='--class gnu-linux --class gnu --class os --unrestricted'
Run the following command to update the grub2 configuration:
If password protection is enabled, only the designated superuser can edit a Grub 2 menu item by pressing 'e' or access the GRUB 2 command line by pressing 'c'
If GRUB 2 is set up to boot automatically to a password-protected menu entry the user has no option to back out of the password prompt to select another menu entry. Holding the SHIFT key will not display the menu in this case. The user must enter the correct username and password. If unable, the configuration files will have to be edited via the LiveCD or other means to fix the problem
You can add --unrestricted to the menu entries to allow the system to boot without entering a password. Password will still be required to edit menu items.
More Information: https://help.ubuntu.com/community/Grub2/Passwords
This recommendation is designed around the grub bootloader, if LILO or another bootloader is in use in your environment enact equivalent settings.