SSH certificates offer the best security and scalability among authentication methods for Linux servers. They address the challenges of deploying and rotating SSH credentials at scale, providing better scalability than SSH keys, revoking access centrally, and short-lived SSH certificates. While setting up an SSH CA and authorizing clients can be complex, tools like Infisical simplify the process. With Infisical, users can create Certificate Templates to define access policies, request SSH certificates, and load them into the SSH agent, providing secure and centrally managed access to Linux servers.