How to Secure Single Mode Linux

Open a shell and login as root. Type:

[root@server ~]# /sbin/grub-md5-crypt
Password:
Retype password:
$1$ZqLKR0$cimxs9UxGPM11IG/U.FW41
vim /boot/grub/grub.conf

Add this right after the timeout line:

password --md5 <password-hash>

OR

password --md5 $1$ZqLKR0$cimxs9UxGPM11IG/U.FW41

Reboot the system. In order to access the grub menu you have to type p and then the password.