2014-khattak-look
findings extracted from this paper
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Before censorship the local ISP resolver handled ≥99% of SOHO DNS queries for blocked categories; post-YouTube block, local ISP resolver usage fell to 68–74%, with Google Public DNS rising to 14–19% of queries and OpenDNS/LEVEL-3 also gaining significant share. Simultaneously, unique web-proxy domains in SOHO traffic averaged only 1 pre-block, jumped to 41 on average post-block, and peaked at 114 unique proxy domains on the block day itself.
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Pakistan's censorship used layered, evolving mechanisms: DNS redirection by local ISP resolvers appeared in all post-block traces, supplemented by HTTP 3XX redirection to a local provider's error page in Sep 2012 and shifting to RST injection by Aug 2013 (where ≈95% of YouTube HTTP requests received no response, vs. ≈2% pre-block). Porn blocking similarly combined DNS redirection with IP blocking (41% blacklist overlap) in Sep 2012 and RST injection in Aug 2013.
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Before censorship, porn traffic averaged 8.4–11.5% of HTTP bandwidth across residential and SOHO users respectively. Post-censorship, this fraction fell to ≈3.5–4.0% for residential and ≈2.0–3.7% for SOHO users. Even after accounting for traffic shifted to unblocked alternate porn domains and the contemporaneous SSL/VPN increase, porn traffic did not return to pre-block levels, suggesting censorship achieved partial demand suppression despite being bypassable via alternate DNS resolvers.
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On the day of YouTube's block in Pakistan (18 Sep 2012), SOHO users' HTTP:SSL traffic ratio collapsed from ~38:1 pre-censorship to ~3.2:1, and remained at ~3.25 eleven months later (Aug 2013), indicating rapid and sustained mass adoption of SSL-based circumvention. A supplementary survey of ~700 Pakistani users confirmed 57% used SSL-based VPN software (UltraSurf, OpenVPN, Hotspot Shield) to access YouTube.
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YouTube held an average of ~97% of SOHO video bandwidth across four pre-block traces. On the block day (18 Sep 2012) this dropped to 15.8%, with DailyMotion absorbing ~82% of 'Others' traffic. Eleven months later (Aug 2013), YouTube's unencrypted video share reached 0%, with Tune.pk at 57.6% and DailyMotion at 40.9% of total video bandwidth, reflecting a durable market reallocation among video platforms.