Password protected GRUB Legacy

Add password into the main GRUB section to password protect the interactive operations (i.e. editing menu entries and entering the command-line interface). Optionally add lock into a menu entry to prevent it from executing if no valid password is provided by the user.

$ grub-md5-crypt 
Password: 
Retype password: 
$1$K0Kh10$OmQNQOthH8jppDFQ5TYx5/

$ chmod 600 /boot/grub/menu.lst
$ vim /boot/grub/menu.lst
default 0
...
password --md5sum $1$K0Kh10$OmQNQOthH8jppDFQ5TYx5/

title Linux
kernel ...

title OpenBSD
lock
kernel ...