Generate a preferred password for GRUB $($CentOS $7$ provides tools for setting password for GRUB$)1\mathrm{.}1[$Screenshot$]$ Execute # grub$2-$setpassword in terminal and press ENTER to create your own encrypted password for GRUB $($for testing purpose, the GRUB$$s password is better to be different than the root user$$s password$).$ If your CentOS doesn$$t have $$grub$2-$setpassword$.$ You can install it manually with the command $$yum install grub$2-$y$$ and then update grub$2$s configuration with command $$grub$2-$ mkconfig $-$o $/$boot$/$grub$2/$grub$.$cfg$.1\mathrm{.}2$ Double$-$check if a new file $/$boot$/$grub$2/$grub$.$cfg is generated as soon as the password is set. $2$ Enable the password for a preferred Boot entry. $2\mathrm{.}1[$Screenshot$]$ Open the $/$boot$/$grub$2/$grub$.$cfg file with vi$/$vim and find the boot entry that you want to harden with a password. Again, as Fig$\mathrm{.}3$ shows, there are $2$ entries that we can enable the bootloader password for. The configuration file includes the configuration data for both entries. To find the configuration data for an entry quickly, you can search keyword $$menuentry$$ in vi$/$vim and go through the results until you see a line like the highlighted section in Fig. $8.$ Note that the highlighted section in Fig. $8.$ is the configuration data for the SECEND entry because the content next to $$menuentry$$ is $$CentOS Linux $(0-$rescue$-.....$ If you want to enable the bootloader password for the first entry, you$$d find the configuration data for the first entry. To enable the password for an entry, all you need to do is to remove the $--$unrestricted flag from the entry$$s configuration data, and then save and exit vi$/$vim$.$ Please only enable bootloader password for one of the entries. $2\mathrm{.}2[$Screenshot$]$ Reboot the system, select the entry that you just removed $--$unrestricted$$ from, press ENTER, and then test if you need to enter the bootloader password before logging into CentOS $($username is root, bootloader password was created in step $1\mathrm{.}1).$