How to Password Protect Single User Mode in CentOS 7

Tecmint: In single user mode, the system executes a single-user shell where you can run commands without any login credentials (username and password), you land straight in a limited shell with access to the entire filesystem. This is a massive security hole since it gives intruders direct access to a shell (and possible access to the the entire filesystem). Therefore, it’s important to password protect the single user mode on CentOS 7 as explained below.