AmneziaVPN

Six Months After tun0 Leak: Which Android VPN Clients Fixed Server Address Exposure and Which Ignored It

A detailed investigation reveals that Android VPN clients suffer from two distinct server address leaks when split tunneling is enabled. The first leak, tied to an unprotected local SOCKS proxy on 127.0.0.1, was quickly mitigated by most Xray and sing-box based clients through random ports and passwords. The second, more persistent leak allows excluded applications to bind sockets directly to the tun0 interface and discover the VPN server IP without root or special permissions. Only TeapodStream and OlConnect implemented owner-UID checks using ConnectivityManager.getConnectionOwnerUid, yet both initially mishandled the INVALID_UID response returned for excluded apps. AmneziaVPN has unmerged pull requests that correctly reject unknown owners, while sing-box offers a manual package_name_regex rule. v2rayNG closed the report as not planned, and major clients including WireGuard for Android, Mullvad, Proton VPN and others have issued no statements.

Part 2: How Third-Party Developers Closed the tun0 Leak in AmneziaVPN on Android

Third-party contributors to AmneziaVPN have detailed their fix for a VPN tunnel bypass affecting excluded applications on Android. The vulnerability allows any app, even those disallowed from the VPN, to bind sockets directly to the tun0 interface using SO_BINDTODEVICE and thereby discover the VPN server address. The team implemented a packet filter inside the client that queries Android via ConnectivityManager.getConnectionOwnerUid to determine packet ownership and drops traffic from unknown UIDs. The solution was integrated into both the Xray and AmneziaWG traffic paths, with the AmneziaWG hook placed inside amneziawg-go after packet parsing. Testing with leak_probe.py showed zero successful bypass attempts out of six methods when the filter was active, compared to six out of six without it. The developers submitted three pull requests and released a side-loaded test build, while noting remaining limitations such as raw sockets and tethering scenarios.

Free VPNs Fail Within Days as Russian Filters Detect Tunnels Without Decrypting Traffic

Free VPN services promoted in Telegram now stop working after just a few days, with Instagram Reels freezing, YouTube stalling in endless loading, and Google Gemini returning 403 errors. Modern Russian content filtering systems have advanced beyond simple IP blocking and can identify proxy tunnels through indirect traffic characteristics such as packet sizes, inter-packet intervals, and TLS handshake structures. A common failure pattern involves connections succeeding initially before data transfer abruptly slows or drops after roughly 16 KB, a behavior linked to deep packet inspection recognizing proxy patterns. Users and developers counter these detections with techniques including packet fragmentation, reduced TCP segment sizes, and tools like zapret to desynchronize analyzers while preserving normal server-side flow. Services such as sing-box employ uTLS to better mimic legitimate browser TLS fingerprints, while ShadowTLS v3 and padding methods help mask connections as ordinary HTTPS sessions to allowed resources. Recommended working options include AmneziaVPN, Cloudflare WARP, Red Shield VPN, and self-hosted setups on Xray or sing-box, though some claims around hynet.cloud lack independent verification.