Scalable and secure access with SSH

This post details Meta's implementation of signed SSH certificates with principals to achieve scalable and secure access to its vast server infrastructure. It addresses the limitations of traditional password and public-key management for large-scale environments, introducing a robust system that leverages certificate authorities for authentication, principals for authorization, and centralized logging for accounting. The post also outlines the implementation details, including the creation of security domains and the configuration of SSH servers to enforce access policies.