Comprehensive Internet-wide scanning enables cross-IP tracking of users and devices by correlating stable cryptographic identifiers — TLS certificates or SSH host keys presented by home routers and cable modems — with public geolocation data across DHCP lease changes, defeating the anonymity assumption behind dynamic IP addresses.

High-speed Internet-wide scanning enables a censor or attacker to locate every publicly reachable host vulnerable to a newly disclosed flaw within hours of disclosure; in a concrete example, 3.4 million UPnP-vulnerable devices were identified in under 2 hours — faster than network operators could apply patches — with a 150-SLOC probe module written in approximately 4 hours.

§4.3 detection

Obfsproxy (predecessor to obfs4) listens on randomized ports as an explicit defense against discovery by comprehensive Internet-wide scanning, because an adversary must scan all 65,535 ports to locate bridges rather than a single known port — multiplying scan cost by roughly 65,000× relative to a single-port sweep.

§4.4 defense

By scanning ports 443 and 9001 and fingerprinting responses with Tor's TLS v1 cipher-suite handshake pattern, ZMap identified 79–86% of all allocated Tor bridge fingerprints in a single scan, demonstrating that bridges whose protocol is distinguishable are largely discoverable through comprehensive Internet-wide scanning even though their addresses are not publicly listed.

§4.4 detection

ZMap completes a single-port scan of the entire public IPv4 address space in under 45 minutes from a commodity machine with a gigabit Ethernet connection, over 1,300 times faster than the most aggressive Nmap configuration. A single-probe scan achieves approximately 97.9% coverage of live hosts, rising to 98.8% with two probes and 99.4% with three probes.

§3, §3.2, §3.4, Table 1 evaluation

TLS-Scanner, a subproject of the TLS-Attacker suite, automates handshake probes across deployed TLS hosts and has been used in published IPv4-wide scanning studies. It surfaces supported protocol versions, enabled extensions, and known vulnerabilities, providing a ready-made audit tool for circumvention infrastructure operators.

2024-niere-tls-attacker §2 Impact (Academic Perspective) tls-fingerprintmeasurement-platform

Russia's Ministry of Digital Development issued guidelines effective April 15, 2026 requiring popular apps to detect and restrict access from VPN-using devices. RKS Global's analysis of 30 popular Russian Android apps found that 22 of 30 implement VPN detection, and 19 of those transmit the detected VPN status to their servers. This represents a shift from network-layer blocking (TSPU) to app-layer enforcement as an additional censorship vector.

2026-rks-russian-apps-vpn-detection §3, §4 tls-fingerprintml-classifier

The RKS Global report documents a two-tier Russian censorship architecture: TSPU network-layer blocking (documented by Xue et al. 2024) at the ISP level, now supplemented by mandated app-layer VPN detection in the 30 most popular Russian Android apps. This layered approach means a circumvention tool that successfully bypasses TSPU at the network layer can still be detected and reported by the app layer, closing the gap that network-only circumvention leaves open.

2026-rks-russian-apps-vpn-detection §2, §7 tls-fingerprintml-classifiermiddlebox-interference

The largest single source of censored domains in the GNL is MESA lab's SNI monitoring dataset (E21-SNI-Top200w.txt) containing 57,362 censored domains, and E21-SNI-Top120W-20221020.txt with 36,467 domains—totaling over 93K domains from network tap data alone for a single country (E21 = Ethiopia per InterSecLab attribution). A separate Xinjiang dataset (XJ-CUCC-SNI-Top200w.txt) contains 13,604 domains. These datasets "do not seem to come from popular domain lists, and instead appear to be gathered from network taps," confirming that Geedge builds censorship target lists directly from passive traffic observation.

2026-sheffey-geedge §4.2, Table 3 dpisni-blockingmeasurement-platform

Of 6,915,266 domains extracted from the 572 GiB Geedge Networks Leak (GNL), 298,955 censored domains (93.7% of all GNL-censored domains) appear in neither Tranco top-1M nor CitizenLab test lists. Measurements across China (Guangzhou/Nanjing), Myanmar, Pakistan, and Algeria confirmed censorship via DNS injection and SNI-based TLS connection termination. The GNL covers 25–62% of Tranco-censored domains across countries, showing substantial but incomplete overlap. This vendor-side ground truth reveals a censorship surface roughly two orders of magnitude larger than curated academic test lists.

2026-sheffey-geedge §4.1, Table 2 dpisni-blockingdns-poisoningmeasurement-platform

CensorAlert aggregates censorship signals from heterogeneous open sources — including OONI, Cloudflare Radar, NetBlocks, GitHub Issues of circumvention tools (Hysteria, Xray), Net4People BBS, NTC Party forum, Mastodon, X, Telegram channels, and arXiv — normalizing each item into a common schema preserving timestamp, source, raw data, and provenance with a link to the original content.

2026-zohaib-extended §2 (Data Sources) measurement-platform