Question: How to protect single user mode with root password
To make your linux machine more secure. Protecting its single user mode with password is one of the good practice.
Their is file called /etc/inittab in linux which decides the linux box runlevel while system boots. inittab file contains 4 fields and which are given below.
Fields in /etc/inittab
label: run_level: action :process
To protect your single usermode with root password. Add the below line in file /etc/inittab
1. SU , is just a label
2. S , enter in to single user mode
3. wait , starts the process and waits for it to complete before going on to the next inittab entry.
4. /sbin/sulogin , which only allows root user to login
Reboot the machine and go to single user mode it will ask for root password