How we built a real-time DNS and VPN leak detection engine (architecture and methodology)

How we built a real-time DNS and VPN leak detection engine Most VPN users assume that once connected, their IP address and DNS requests are fully protected. In practice, this is not always the case. DNS leaks,WebRTC exposure, and IPv6 misconfigurations can reveal the user's real network identity even when a VPN tunnel is active. This article explains the architecture and methodology behind a real-time leak detection engine designed to identify these failures. The core problem VPN tunnels encrypt traffic between the user's device and the VPN server. However,several components of the network stack may bypass this tunnel: • DNS resolvers • WebRTC STUN requests • IPv6 routing • OS-level fallback mechanisms If any of these expose the original network interface, privacy is compromised. Leak detection must therefore validate actual network behavior not just connection status. System architecture overview The leak detection engine is built using a layered validation model: Detection layer Veri