Background: 15 years of experience in software and apparently spoiled because it was already set up correctly.
Been practicing doing my own servers, published a test site and 24 hours later, root was compromised.
Rolled back to the backup before I made it public and now I have a security checklist.
Do not allow username/password login for ssh
This is disabled by default for the root user.
$ man sshd_config
...
PermitRootLogin
Specifies whether root can log in using ssh(1). The argument must be yes, prohibit-password,
forced-commands-only, or no. The default is prohibit-password.
...