Censors in Russia, Iran, and India implement all three measured censorship techniques simultaneously: block pages, RST injection, and TTL anomalies. Iran and Cyprus censoring ASes censor content across many URL categories (including General News, Internet Services, Pornography, Gambling), while most other censoring ASes restrict only a few category types.
From 2017-cho-churn — A Churn for the Better: Localizing Censorship using Network-level Path Churn and Network Tomography
· §4, Table 2
· 2017
· Emerging Networking Experiments and Technologies
Implications
Protocols deployed in Russia, Iran, and India must defeat all three detection surfaces independently — evading RST injection alone is insufficient when block-page injection and TTL-based packet forgery are also deployed.
Broad category-agnostic censors like Iran and Cyprus warrant more aggressive obfuscation since they block across content types rather than targeting a narrow political URL list.