2023-ortwein-towards
findings extracted from this paper
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AS201776 (Miranda-Media Ltd) is responsible for the largest volume of Russian transit censorship by destination IP count, affecting approximately 16,000 IP addresses in Ukraine from US and Sydney vantage points. AS3216 (PJSC Vimpelcom) has the widest geographic reach—delivering blockpages for traffic destined to 8 countries—but impacts no more than 1,000 IP addresses per country from any single vantage point.
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The authors' blockpage-based methodology cannot detect transit censorship implemented via TCP RST injection or packet drops, because distinguishing these from transient network errors requires identifying their location on the routing path. As a result, the 8-country, 6-AS finding is explicitly characterized as a lower bound on the true extent of Russian transit censorship.
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Scanning the IP address spaces of 18 countries surrounding Russia, the authors identify Russian transit censorship affecting at least 8 countries (Afghanistan, Azerbaijan, Kyrgyzstan, Kazakhstan, Lithuania, South Korea, Tajikistan, and Ukraine), attributable to at least 6 Russian ASes. Only 2 of these 8 countries (Kyrgyzstan and Kazakhstan) had been reported in prior work, and the collateral damage is characterized as a lower bound due to the study's blockpage-only methodology.
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The study's three vantage points (US university, AWS Sydney, AWS Tokyo) produce substantially different transit censorship observations: the US vantage point detects blockpages in all 8 affected countries, while Sydney and Tokyo detect transit censorship only in Kazakhstan and Ukraine. This variance is attributed to routing path differences across vantage points, confirming that transit censorship coverage is highly path-dependent.
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AS60299 (Mezhdugorodnyaya Mezhdunarodnaya Telefonnaya Stanciya Ltd) and AS201776 (Miranda-Media Ltd) deploy commercial DPI technology manufactured by Russian company VAS Experts to perform transit censorship. Ukraine is subject to transit censorship by the most Russian ASes (at least 5: AS3216, AS25227, AS35816, AS47203, AS201776), likely due to post-2022 re-routing of Ukrainian Internet traffic through Russian telecommunications infrastructure.