I recently setup a Mastodon server on Digital Ocean. As part of the instructions you must disable password authentication via ssh on your server.
On Ubuntu 20.04 this required editing /etc/ssh/sshd_config, locating the entry PasswordAuthentication, uncommenting it if it was commented out, and setting the value to no. Then restarting ssh via
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systemctl restart ssh.service
Today, I wanted to disable password authentication on a mac server. It’s just about as easy but searching the internet for answers found many old answers that didn’t work. They were instructions for older version of macOS. I finally found instructions for newer versions (at least for Big Sur) . Here are the instructions I used that I found at this site.
Instead of editing sshd_config directly, you add a file in /ect/ssh/sshd_config.d with a .conf extension to that directory. In that file add the entries you want to customize. In addition to PasswordAuthentication you must add ChallengeResponseAuthentication and set them both to no:
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PasswordAuthentication no
ChallengeResponseAuthentication no
And that’s it. You don’t even need to restart the ssh server. The changes take effect immediately.