Ssh

A working guide to using a YubiKey for SSH on a real Linux fleet — the four knobs (resident, touch, PIN, agent), a four-mode policy for root and Ansible, software-only alternatives, and where SSH CAs fit in.

SSH punching for everyone who only knows ssh user@host — how -D replaces a corporate VPN, -R replaces a mesh VPN for NAT’d boxes, and -L forwards Unix sockets. 3 flags, 3 bonuses, 1 man page.