Ctrl-Alt-F4 will give you a prompt for
tty3. Note that it is one number less.
Take a look at the contents of
To prevent root from logging in on this device, take out tty3 from this listing. Note, you can always login as another user, then, su to root. Below is an example of the default “/etc/securetty” that allows root to login to everything:
cat /etc/securetty console vc/1 vc/2 vc/3 vc/4 vc/5 vc/6 vc/7 vc/8 vc/9 vc/10 vc/11 tty1 tty2 tty3 tty4 tty5 tty6 tty7 tty8 tty9 tty10 tty11