See: https://lab.uberspace.de/howto_automatic-deployment/#securing-your-deployment-process-optional-advanced

Generate an ed25519 SSH key using current best practices from 2025. Rotate your keys, assign a useful comment, and use SSH-Agent and Agent Forwarding

Used to install SSH key

“Many users have implemented Secure Shell (ssh) to provide protected access to a remote Linux system, but don’t realize that by allowing password authentication, they are still open to brute-force attacks from anywhere on the Internet.”