I spent 6 months building VPN/proxy security testing tools and analyzing 47 commercial services. The results were eye-opening. Testing Methodology Packet capture analysis (Wireshark on public WiFi) DNS leak detection WebRTC STUN leak testing IPv6 leak detection Kill switch verification IP rotation monitoring Results 47 services tested: 31 VPNs (22 passed, 9 failed) 16 proxy services (6 premium passed, 10 free proxies all failed) Overall failure rate: 40% Key Findings VPN Failures (9 out of 31) The most common failure modes: DNS leaks during kill switch engagement WebRTC STUN bypassing VPN tunnel IPv6 traffic not routed through VPN tunnel Kill switch race condition (leaked real IP during connection handshake) Free Proxies (100% Failure Rate) All 10 free proxy services tested failed security tests: Zero encryption 30% actively performed MITM with script injection 10% performed DNS hijacking for ad injection All logged traffic without disclosure Most shocking: 3 free proxy services actively injected advertising…