The /etc/securetty file allows you to specify which TTY devices the root user is allowed to login on. The /etc/securetty file is read by the login program usually /bin/login. Its format is a list of the tty devices names allowed, and for all others that are commented out or do not appear in this file, root login is disallowed. Disable any tty that you do not need by commenting them out # at the beginning of the line. Edit the securetty file vi, /etc/securetty and comment out the following lines:
tty1
#tty2
#tty3
#tty4
#tty5
#tty6
#tty7
#tty8
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Which means only root is allowed to login on
tty1. This is my recommendation, allowing root to log in only on one tty device and use the
su command to switch to root if you need more. devices to log in as root.