Automatic key generation: When you start the container for the first time, id_ed25519 (private key) and id_ed25519.pub (public key) will be automatically generated in the volume-mounted ./data folder.

Enforce: The -k _ argument is a flag that requires the public key to be verified upon connection.

Prevention of springboards: If you do not include this, third parties who know your server's IP and port can use your server as a relay.