Step 2: Securing OpenSSH

The OpenSSH server configuration should be located at /etc/ssh/sshd_config but we aren't going to edit this file. We are going to create a new file at /etc/ssh/sshd_config.d/hardening.conf. (add video)

First, we will disallow connecting with a password. For that we are going to need a SSH key. If you already have one skip the next few steps (until where?).

To create a SSH key, we are going to run this command on our device (not the server!): ssh-keygen -t ed25519. Press Enter once to confirm the path (leave as default!). It will then ask for a passphrase. You can leave it empty if you can assure that no one will ever get access to the private key, else set one.
After this, blah blah blah...