Securing SSHD

To prevent root access

The SSHD (ssh-daemon) config file is typically located at /etc/ssh/sshd_config on most linux systems (like the CentOS boxes used for this class!)

There are many options in the file, but only one we're interested in right now:

...
# PermitRootLogin yes
...

To ensure that it is completely impossible to log in as root, simply change it to:

...
PermitRootLogin no
...

Then, we need to restart the SSHD service. On CentOS, this is as easy as sudo systemctl restart sshd