geedge.lantern.io
detection confidence: high public

An internal talk deconstructing MESA Lab's own WWW2024 paper "Identifying VPN Servers through Graph-Represented Behaviors" (VPNTracker) confirms it was built on the group's own internal production log data ("组内数据"), and details its core active-probing feature: "Stealth Ports" (TCP ports observed open in passive traffic that refuse/ignore active probes) combined with vendor-specific patterns in the error responses VPN servers return to out-of-protocol active probes (e.g. a DNS query sent to the port), fed into a graph neural network over client-IP/server-IP/port relationships; framed explicitly as anti-geo-fraud tooling against services like ChatGPT, Netflix, and NetEase Cloud Music.

被动流量里开放端口,但主动探测不开放(Stealth Ports) 同一个厂商的VPN server回复相似的错误信息,前人忽略了错误信息。[dig google.com @ip:域名不存在,解析失败,超时…] ... 研究场景:网站地理欺诈(Geo-fraud),ChatGPT、Netflix、网易云…

Defense implications

censorscn
capabilityactive-probing-impl

extracted_by: claude-sonnet-5 · added 2026-08-26 · id: 2026-vpntracker-stealth-ports-ac

Related findings

detection

A June 2022 IIE CAS master's thesis, 'Research on Key Technologies of DoH Traffic Identification' (author name redacted, supervised by Professor Fang Binxing -- publicly known as chief architect of the Great Firewall and later Geedge Networks' founder/chief scientist), develops: (1) a light-load connection-multiplexing active scanner to discover DoH resolvers at scale, (2) a one-class ML classifier trained only on DoH samples plus TLS statistical features to catch DoH traffic missed by rule matching, and (3) a DoH fingerprinting method that strips HTTP/2 control-frame noise -- explicitly aimed at 'identifying users visiting websites from passive DoH traffic,' i.e. website fingerprinting through encrypted-DNS-wrapped connections.

detection

A 2024 CAS/IIE master's mid-term thesis report, "面向DPI中间件的探测行为识别关键技术研究" (Key Technologies for Identifying Probing Behavior Targeting DPI Middleboxes), builds and evaluates a system that detects and fingerprints active-measurement traffic from OONI, Censored Planet, and GFWatch/GFWeb (via their server-contact patterns, distinct-domain-count thresholds, and response-timing signatures — e.g. flagging a probing srcIP once it queries ≥500-2000 distinct domains at one dstIP), and separately trains a graph-neural-network classifier on raw packet bytes to detect Geneva/SymTCP-style automated censorship-evasion probes, explicitly framed as reducing the DPI middlebox's exposure of its own characteristics to circumvention researchers.

detection

A 2024 University of Chinese Academy of Sciences course taught within MESA Lab's research group (instructor name redacted) trains students to fingerprint and detect censorship-measurement tools -- OONI Probe's fixed built-in control-server domains, ICLab's User-Agent behavior, and the large-domain-fan-out pattern shared by Satellite/Iris/Quack/GFWatch -- and to build ML classifiers (citing IEEE Access 2019, CoNeXT 2019 CLAP, and USENIX 2023 ML-TRW) that detect DPI-evasion probing traffic in the style of Geneva and StateDiver, explicitly framed as protecting DPI middleware from being probed and evaded.

evaluation

A MESA Lab student research report catalogs the GFW's known Shadowsocks-detection methodology (passive detection via first-packet length/entropy; active probing triggered after as few as 13 legitimate client connections, typically within seconds of the first legitimate connection) alongside six published ML-based Shadowsocks traffic-classification techniques (a packet-size-image CNN at >98% accuracy, random-forest on flow/host/DNS-behavior features, PCA-Pearson feature selection), compiled as apparent background research for in-house detection work.

detection

Two versions of an academic active-probing VPN-server-detection paper ("VPNChecker"/"VPNSniffer", WWW'24) held in this corpus specifically profile Psiphon3: Psiphon3 servers account for the single largest share (6.64%) of labeled VPN servers in the authors' ISP dataset, most respond to an OpenVPN probe by silently timing out rather than returning the standard OpenVPN response (a "probe-resistant" behavior the paper explicitly attributes to Psiphon3), and Psiphon3 servers share a small number of characteristic "Probing Port Combinations" (e.g. {443,53,22}, {443,554,22}) across the vendor's fleet that the paper's graph-based classifier uses to link servers together.

detection

An internal MESA Lab presentation by a MESA Lab researcher (name/email redacted) describes 'CartoDNS', a global active/passive encrypted-DNS reconnaissance system that uses DNS-watermark injection across multi-region probing nodes to map DoT/DoH/DoQ resolver topology; as of the presentation it had discovered 80,000+ DoT, 20,000+ DoH and 4,000+ DoQ IPv4 resolvers (plus 1,100+ DoT and 500+ DoH over IPv6) and cataloged 500+ service providers with concrete IP ranges (Cloudflare, Google, Quad9, AdGuard, 360, Alibaba, Tencent, etc.), running continuously since December 2021.