DEFENSES
vless VLESS (V2Ray)
17 papers on file
- 2025-iran-shutdown-measurement Characterizing Iran's Phased National Internet Shutdown in 2025: A Progressive and Distributed Action
- 2026-amigocarra-bypassing-russian-federation-s Bypassing the Russian Federation's mobile internet whitelists—we're stuck, looking for real-world experience
- 2026-anon-github-2026-6-dns GitHub无法访问？2026年最新6种解决方法（含DNS修改与加速工具） | 二毛
- 2026-anon-gpt-6-astra GPT-6 Astra 跨过网络安全门槛：机场数据泄露、平台问责与吉隆恢复周报 | 二毛
- 2026-ferrel-aegis-adversarial-entropy-guided AEGIS: Adversarial Entropy-Guided Immune System -- Thermodynamic State Space Models for Zero-Day Network Evasion Detection
- 2026-gohoski-russia-possible-tun [Russia] Possible TUN detection on DPI level?
- 2026-molotoves-wall-behind-wall A Wall Behind A Wall : In Fujian
- 2026-pooribitwise-iran-advanced-dpi [Iran] Advanced DPI is reassembling TCP fragments to extract SNI on VLESS/WS + CDN
- 2025-aryapour-stealth-blackout Iran's Stealth Internet Blackout: A New Model of Censorship
- 2025-miaan-stealth-blackout Iran's Stealth Blackout: A Multi-stakeholder Analysis of the June 2025 Internet Shutdown
- 2025-mixon-baca-hidden Hidden Links: Analyzing Secret Families of VPN Apps
- 2025-pirooz-gthb-internet-completely-blocked Internet is completely blocked in Iran (2025-06-17 to 2025-06-26)
- 2024-xue-tspu-russia Tspu: Russia's decentralized censorship system
- 2023-wu-fully-encrypted-detect How the Great Firewall of China detects and blocks fully encrypted traffic
- 2022-blocking-tls-circumvention Large scale blocking of TLS-based censorship circumvention tools in China
- 2022-oftenhamed-vless-tls-has Vless + TLS has a weird behavior on Iran VPS
- 2020-v2ray-weaknesses Summary on Recently Discovered V2Ray Weaknesses
31 findings tagged here
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Community-maintained public CIDR lists of Russian mobile whitelist ranges allow operators to identify specific whitelisted IP blocks within cloud providers: a /22 subnet inside Yandex Cloud's /16 pool appears on these lists, while the ephemeral addresses from a different /20 pool of the same provider do not. Reserving a static IP from the whitelisted /22 allows the Reality handshake to complete and traffic to proxy from external vantage points, though in-whitelist passage on a real mobile device remained unconfirmed at time of writing.
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VLESS+Reality with uTLS and decoy SNI pointed at popular domains (vk.com, cloudflare.com) bypasses standard DPI blocking on MTS and has operated stably for one real user over several weeks with thousands of connections logged. However, an identical configuration failed to establish a single connection for a second user on the same carrier but in a different network segment (Moscow number vs. regional/southern number), including during periods confirmed to be outside whitelist activation.
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As of 2026, AnyTLS lacks a standardized subscription link format (unlike VLESS/Trojan/Hysteria2), requires manual JSON configuration distribution, and is supported primarily by sing-box with limited support in v2rayNG and Shadowrocket. The guide explicitly warns it is unsuitable for production environments and recommends VLESS or Hysteria2 for production deployments and Hysteria2 for high-performance needs.
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Compared to peer protocols, AnyTLS rates 'medium' performance (vs. VLESS 'high', Hysteria2 'very high', TUIC 'high'), uses TCP/TLS transport (vs. UDP/QUIC for Hysteria2 and TUIC), and relies on padding-based obfuscation vs. REALITY/WebSocket (VLESS) or HTTP/3 framing (Hysteria2). Client ecosystem support is currently limited primarily to sing-box, vs. broad cross-client support for VLESS, Trojan, and Hysteria2.
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As of 2026-02-23, the dominant consumer GFW circumvention stack for mainland Chinese users is: Clash Verge Rev on Windows/macOS, Clash Meta for Android, and Shadowrocket (requiring a non-mainland Apple ID) on iOS — all configured via subscription URLs purchased from commercial 'airport' (机场) proxy services starting at ¥2/month.
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The article documents that large-scale 'one-click' commercial VPN providers with static protocol stacks have become effectively non-viable in China, while subscription-based proxy node services using open-source clients (Clash, Shadowrocket) with server-side rapid IP and datacenter switching demonstrate substantially greater resilience to GFW blocking waves.
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Adversarial pre-padding — prepending stochastic byte noise to packets — degrades ET-BERT encrypted traffic classification accuracy from >99% to 25.68%, exposing a structural vulnerability in all payload-byte-dependent detection systems. White-box adversarial attacks (Ayaka AH-MSI) additionally achieve evasion rates exceeding 99.5% against standard continuous-time sequence models via Manifold Shattering, where adversaries align malicious temporal distributions with benign baselines.
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AEGIS, a flow-physics-only ML classifier using a Hyperbolic Liquid State Space Model evaluated on a 400GB adversarial corpus including VLESS Reality, GhostBear, and AMOI-morphed traffic, achieves F1-score 0.9952, 99.50% TPR, and 0.2141% FPR at 262.27 µs inference latency on an RTX 4090. The system discards all payload bytes and classifies traffic exclusively on 6-dimensional flow physics: packet size, inter-arrival time, directionality, TCP window size, TCP flags, and payload ratio.
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Automated proxy engines (e.g., Xray-core running VLESS Reality in automated mode) generate deterministically rigid inter-arrival time distributions because they cannot synthesize the stochastic variance of human-driven IAT, even when volumetrically anchored to benign distributions ('Fat Middle' anchoring via AMOI). The AEGIS Thermodynamic Variance Detector identifies this rigidity via Shannon Entropy of hidden states across 1,000-packet causal windows, rendering volumetric anchoring mathematically distinguishable from genuine human traffic.
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Flow-physics classifiers face a fundamental 'Human Entropy Horizon': when VLESS Reality multiplexes true human entropy (a human actively browsing web applications), AEGIS achieves a detection rate of only 1.17%, because XTLS wrappers impart near-zero mechanical overhead and the temporal physics remain entirely stochastic. This implies adversaries operating at human interaction speeds can evade flow-based detection, but must abandon automated high-throughput C2 scripts.
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On Beeline mobile internet (AS16345, Russia), enabling TUN mode with a VLESS+REALITY proxy consistently triggers ISP-level connection degradation after 5–15 minutes, while using the same proxy in HTTP/SOCKS5 proxy mode produces no such effect. The detection is reproducible across two independent GUI clients (v2rayN and Throne) with stock settings, suggesting the DPI trigger is the TUN traffic pattern rather than a client-specific artifact.
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The TUN-mode detection occurs exclusively on Windows 10 and does not manifest on Android using the same VLESS+REALITY server and Beeline SIM, nor when running as a system proxy on Windows. The effect is also observed to impact all devices sharing the Windows hotspot simultaneously, ruling out endpoint-local causes and confirming the classification occurs upstream at the ISP/TSPU layer.
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As of August 2026 in Fuzhou, Fujian, most censorship-resistant service providers are non-functional; a small number of providers using v2ray remain partially functional, while Tor Browser bridges and Snowflake are no longer usable.
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Iran's DPI blocks VLESS/WS traffic routed through Cloudflare CDN in full-strict TLS mode with regularly rotated clean Cloudflare IPs, demonstrating that CDN-fronted traffic is not opaque to the censor and that IP-layer evasion (using clean CDN IPs) is insufficient when the SNI is fingerprinted.
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The Russian DPI maintains two whitelists that exempt flows from the freeze: (1) a SNI-based whitelist covering select domains (visible in the TLS ClientHello), and (2) a CIDR-based whitelist of IP subnets for trusted destination servers. The SNI whitelist can be exploited by VLESS+Reality clients using an allowed SNI value as the apparent destination; the CIDR whitelist requires routing through an IP from a whitelisted prefix, making circumvention 'extremely difficult' without an intermediate node in a whitelisted subnet.
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Beyond business-filing cross-references, the paper introduces a method of linking VPN provider families by showing they share VPN server cryptographic credentials (Shadowsocks passwords, server TLS fingerprints) across distinct app identities. This extends prior ownership-attribution methods that relied solely on corporate registry data and code similarity, adding shared live infrastructure as a linkage signal that is harder for operators to obscure.
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Iranian censors actively detected and blocked circumvention proxies in real time during the June 2025 shutdown: MTProto proxies, v2ray tunnels (VLESS and VMESS variants), and Tor bridges using both Snowflake and obfs4 all experienced mixed or degraded success as proxies were identified and blocked.
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Per-flow RTTdiff detection rates are only ~20% because the majority of proxy flows connect to CDN-cached content (Cloudflare, Google, Fastly) that sits within 5ms of the proxy, suppressing the discrepancy. However, aggregating across flows per website visit yields detection rates exceeding 70%—and from the abstract, approximately 80% of top-5K domains generate at least one detectable flow—with half of those detections made within the first 60 packets. This means an adversary can reliably expose client and proxy IPs after just a few website visits.
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Proxy users who resolve DNS locally (at the client) are approximately twice as susceptible to RTTdiff fingerprinting compared to users who resolve DNS at the proxy, across all tested client/proxy location combinations. Local DNS returns IPs optimally reachable from the client's region, which may be geographically distant from the proxy, increasing the proxy-to-server path distance and thus the RTTdiff discrepancy.
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Cross-layer RTT discrepancy (RTTdiff) is a protocol-agnostic fingerprint that exploits an inherent architectural property of all proxy setups: transport-layer sessions terminate at the proxy while application-layer sessions remain end-to-end. Evaluation across 10 proxy protocols—including VMess, Shadowsocks, VLESS, Trojan, XTLS-Vision, and obfs4-wrapped SOCKS—shows near-identical detection rates for all except obfs4, confirming the fingerprint is not tied to any specific obfuscation scheme. At FPR=0.01, per-website detection rates exceed 70% across all tested client and proxy location combinations.
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Obfuscated proxy traffic (including Shadowsocks, VMess, VLESS, Trojan, obfs4, and REALITY) can be reliably fingerprinted by detecting encapsulated TLS handshakes — the inner TLS ClientHello that appears inside an outer encrypted tunnel. This fingerprint is protocol-agnostic: any proxy that wraps TLS-bearing application traffic will produce it. The authors deployed a similarity-based classifier within a mid-size ISP serving over one million users and demonstrated detection with minimal collateral damage.
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While stream multiplexing reduces the visibility of encapsulated TLS handshakes by merging inner connections, the paper cautions that multiplexing plus random padding alone is "inherently limited" as a long-term countermeasure. Censors can adapt by monitoring burst sizes and round-trip counts at the outer-connection level, which remain correlated with the number of inner TLS sessions regardless of padding.
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The GFW's fully-encrypted detector (deployed Nov 2021) operates by exempting likely-benign traffic and blocking the rest. Five inferred exemption rules applied to the first TCP payload (pkt): Ex1 — popcount(pkt)/len(pkt) ≤ 3.4 or ≥ 4.6 (bits/byte); Ex2 — first 6+ bytes are printable ASCII [0x20–0x7e]; Ex3 — more than 50% of bytes are printable ASCII; Ex4 — more than 20 contiguous printable ASCII bytes; Ex5 — first bytes match TLS or HTTP fingerprint. Traffic failing all five exemptions is blocked. Experiments confirmed all rules still held as of February 2023.
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Starting October 3, 2022, more than 100 users reported simultaneous blocking of TLS-based circumvention servers running Trojan, Xray, V2Ray TLS+WebSocket, VLESS, and gRPC. Blocking was port-specific initially (mainly port 443, but also non-443 ports), then escalated to full IP blocking when users switched ports. Domain names were not added to DNS or SNI blocklists. naiveproxy was notably not affected. The blocking was dynamic in at least some cases (browsers could still reach the port, but circumvention tools could not), strongly indicating protocol-level identification rather than blind port blocking.
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The October 2022 blocking wave is the confirmed operational deployment of the fully-encrypted-traffic detector later formalized in Wu et al. (USENIX Security 2023). The detector was therefore in live production from at least late 2022, more than a year before the academic paper describing it was published. This event establishes that the GFW's passive fully-encrypted classifier operates at scale in adversarial real-world conditions, not just in controlled experiments.
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Iran's censorship infrastructure employs IP-list blocking of major media CDNs (Instagram, YouTube, Facebook) that remains effective against VLESS+TLS users on domestic VPS endpoints. Telegram's accessibility—because it is reachable directly by IP without domain resolution—confirms that the IP blocklist targets CDN address ranges specifically rather than applying blanket traffic inspection.
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Community analysis of the Iran VLESS+TLS failure identified DNS poisoning as a primary root cause: domain-based resolution for services like Instagram, YouTube, and Facebook was disrupted even when traffic transited a VLESS+TLS tunnel from a domestic VPS, bypassing the transport-layer obfuscation entirely.
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This primary-source community report documents that Iran's censorship is multi-layered: VLESS+TLS successfully evades transport-protocol detection but is defeated simultaneously by DNS poisoning and CDN IP-list blocking. A circumvention tool that addresses only one layer (transport obfuscation) is insufficient for consistent access in Iran.
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Iran's censorship against VLESS+TLS users on domestic VPS infrastructure is selective by destination type: Telegram, which is accessed by IP, remained reachable, while Instagram, YouTube, and Facebook were blocked or partially inaccessible. This indicates blocking operates at the destination-IP/domain layer independently of the transport protocol.
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Configuring client-side DNS settings within V2rayNG resolves the DNS poisoning component of Iran's multi-layer censorship when using VLESS+TLS from a domestic VPS. This workaround routes DNS queries through the tunnel rather than the local, poisoned resolver, restoring domain resolution for blocked services.
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V2Ray clients emitted TLS ClientHello messages with a hardcoded, rarely-seen ciphersuite (fingerprint ID 8c48b95f67260663 on tlsfingerprint.io) that allowed a machine-learning classifier to identify V2Ray TLS traffic with 0.9999 accuracy; the same classifier could not accurately identify the traffic after the fingerprint was changed. The blocking rule based on the unique ciphersuite could be expressed in a single iptables line.