Linux OpenSSH server deny root user access / log in

Originally published at: https://www.cyberciti.biz/faq/linux-unix-openssh-block-root-user/

How do I block access to root user over ssh session on my Linux server? How can I block root user log in over ssh based session for security reasons?

Shouldn’t something like SELinux used to block the login as well, in case there’s a bug in OpenSSH Server ?