XTLS Vision has never triggered large-scale GFW blocking; one user reports 2.5+ years of uninterrupted use. Developers acknowledge that Vision without Seed produces fixed, distinguishable traffic characteristics and are developing 'Vision Seed' to introduce per-session randomization.

CDN-based proxy protocols avoid permanent IP-level GFW blocking but suffer from instability. IPLC ('no wall crossing') leased lines are stable and fast but expensive and subject to periodic administrative disconnection by the Chinese communications regulator.

Comment by @RPRX, Nov 18 2024 evaluation

Hysteria 2 (QUIC-based proxy) suffered past large-scale GFW blocking events but was broadly functional as of late 2024. Aggressive packet sending causes VPS providers and ISPs—not the GFW itself—to apply rate limits, adding a second failure mode beyond censor detection.

Comment by @RPRX, Nov 18 2024 evaluation

REALITY ('certificate stealing') had produced no large-scale GFW blocking reports as of November 2024, per Xray-core developer @RPRX. Its operational downside is lower throughput compared to aggressive packet-dispatch protocols like Hysteria 2.

Comment by @RPRX, Nov 18 2024 evaluation

Raw UDP P2P gaming traffic was detected and blocked within 1–2 hours. Hysteria 2 port-hopping delayed blocking but the entire server IP was eventually blacklisted once enough ports were consumed. The reporter identified udp2raw + WireGuard (with udpspeeder for packet loss compensation) as the most stable high-performance solution.

Comment by @iopq, Dec 1 2024 deployment

TSG's Context-Based Detector (CBD) evaluates circumvention tool signatures across JA3/JA4 TLS fingerprints, SSL certificate issuer fields, UDP payload length, first-packet byte patterns, server IP ranges, and FQDN matches, often combining multiple conditions with logical AND. Of 29 VPN and circumvention tool signatures logged in the VPN Signature File Update Log (March–November 2024), 21 carry risk level 5 (the maximum), indicating aggressive prioritization of blocking major tools including ExpressVPN, NordVPN, Tor Browser, and Psiphon.

2026-ablove-technical-analysis-geedge §4.1, §4.1.2, Table 3, Table 4 dpitls-fingerprinttraffic-shapeip-blockingsni-blocking

A three-stage detection pipeline exploiting the "dual-role" behavioral fingerprint of single-IP circumvention relays achieved 23.2% recall (96/414 ground-truth relays) with a 0.18% false-positive rate against 97,651 benign TLS servers, for an overall accuracy of 99.5%. The ground-truth set covered OpenVPN, WireGuard, and SOCKS relays identified in a 17 TB single-day backbone trace (WIDE Project, April 9, 2025).

2026-almutairi-server §3.4, Table 1 traffic-shapedpiflow-correlation

The paper identifies a fundamental architectural vulnerability in single-IP circumvention designs: a relay must generate new observable flows (via DNS or TLS SNI) to reach end services after receiving client connections, creating a detectable server-and-client behavioral contrast. A relay accessing user-facing domains (news, social media) scores high on a Relay Suspicion Score (w=0.9) versus infrastructure domains (w=0.1). The paper argues this host-level signal is censorship-invariant and cannot be concealed by link obfuscation.

2026-almutairi-server §2.4, §4 traffic-shapedpisni-blocking

Based on analysis of over 100,000 leaked Geedge Networks documents, InterSecLab (2025) found that Geedge supplied China-GFW-equivalent censorship and surveillance systems to Kazakhstan, Ethiopia, Pakistan, and Myanmar. The systems include deep packet inspection, real-time mobile user monitoring, fine-grained traffic control, regionally customizable censorship rules, and — per WIRED's reporting — ML-based extraction of metadata from encrypted traffic to determine whether a flow is likely from a VPN or circumvention tool.

2026-anon-2026-27-vpn §8 (InterSecLab / WIRED section) dpiml-classifierfully-encrypted-detecttraffic-shape

AnyTLS's default padding scheme operates across 8 levels (stop=8), with initial padding fixed at 30 bytes, small-data padding 100–400 bytes, and medium-to-large data padding chains of 400–500 bytes continuing through multiple 500–1000 byte segments. The 'c' (continue) marker allows multi-stage padding sequences within a single connection burst.

2026-anon-anytls-anytls-sing-box-2026 §2.3 traffic-shapedpi

AnyTLS is a TLS-based proxy protocol maintained by the sing-box team, designed in 2024 and first released in the sing-box dev-next branch. Its core mechanism wraps arbitrary proxy traffic in standard TLS and applies a configurable padding scheme (Padding Scheme) to enhance traffic concealment while maintaining compatibility with standard TLS infrastructure.

2026-anon-anytls-anytls-sing-box-2026 §1.1–1.3 tls-fingerprinttraffic-shapedpi