VPN Security — Internals & Attacks

A VPN is the move you make once you have decided the network underneath you is hostile — you stop trusting the wire and wrap everything in a tunnel you control. But a tunnel is only as good as the handshake that builds it and the config that keeps traffic inside it. This is how IPSec/IKE, OpenVPN and WireGuard actually establish a tunnel, where each one gets attacked — crackable PSKs, leaked configs, DNS and routing leaks, fingerprinting — and how to build one that holds up.