My notes for disabling password logins and switching to SSH key-based authentication to secure access to remote (Debian) servers:
https://www.dwarmstrong.org/ssh-keys/
Shields UP!
@dwarmstrong Can't be bothered with changing the port - the dangerous people will try other ports, but yes, I do that an all my boxes.
Once you are used to it, using keys is far easier than messing with passwords anyway...!