tr   Turkey

The majority of censored websites are blocked in only one or two countries, with political and news content showing the strongest geographic specificity. Figure 3 shows that of domains blocked in China, Iran, and Turkey, only 29 are blocked in both China and Turkey, while 27,852 are China-only and 1,564 are Iran-only, demonstrating that cross-region client-to-client proxying is broadly applicable.

2020-nasr-massbrowser §III-C, Figure 3 evaluation

Between January 2017 and September 2018, ICLab conducted 53,906,532 measurements of 45,565 URLs across 62 countries and 234 ASes, detecting blocking of 3,602 unique URLs in 60 countries via DNS manipulation, TCP packet injection, and block page delivery. Iran blocked 20–30% of Alexa top-500 URLs — more than any other monitored country — while Saudi Arabia consistently blocked roughly 10%. The global trend in detected censorship shows a steady decrease, which the authors attribute to rising adoption of TLS and circumvention tools.

2020-niaki-iclab §V evaluation

ICLab's longitudinal monitoring detected censorship shifts coinciding with political events weeks before press coverage: Turkey's filtering rate rose from roughly 3% to 5% in late April 2017 — with blocked content shifting from pornography to news and political sites — ahead of a June 2017 constitutional referendum. India's censorship dropped from roughly 2% to 0.8% following a net neutrality announcement in late 2017, then partially recovered to roughly 1.5% after mid-2018 regulations clarified that illegal-content filtering would continue. Within the same country, different blocking techniques were applied to different content categories simultaneously (e.g., Turkey used DNS manipulation for illegal/streaming URLs but block pages for pornography and news).

2020-niaki-iclab §V-C, Table III evaluation

Across all tested countries, circumvention and anonymization tools are the most consistently blocked category: www.hotspotshield.com is blocked in 5 of 13 detected censoring countries, and three Tor Project properties (bridges.torproject.org, www.torproject.org, ooni.torproject.org) each appear in the top-10 most broadly blocked domains. Collateral damage is also documented — Iran blocks psiphonhealthyliving.com as a substring match for the psiphon.ca circumvention domain.

2018-vandersloot-quack §6.2, Figure 12 evaluation

By comparing echo-server (bidirectional) versus discard-server (inbound-only) results across 11 censoring countries, Quack finds that only 4 countries (China, Egypt, Jordan, Turkey) also block inbound traffic; the remaining 7 apply DPI exclusively to outbound data. Direction-sensitive blocking is a confirmed capability of deployed middleboxes.

2018-vandersloot-quack §6.3 detection

41% of users (139,042 of 342,650) in the post-coup dataset voluntarily removed 18% of all post-coup tweets by switching to protected mode, deleting accounts, or deleting individual tweets; the largest groups were active users who deleted some tweets (44% of affected accounts) and users who switched to protected mode (22%).

2017-tanash-decline §4.1, Table 1 policy

Zero pro-Gülen topics appeared in the public tweet set post-coup, while 70% of unreachable (deleted/protected) Gülen-related tweets were pro-Gülen; the unreachable rate for Gülen-related tweets was twice the background rate, quantifying rapid directional self-censorship on politically targeted content within days of a government crackdown.

2017-tanash-decline §4.2–§4.3, Table 2 policy

Tor usage in Turkey spiked sharply during the initial days of the July 2016 coup—when ISPs were actively throttling Twitter—but declined steadily in subsequent months back toward pre-coup baselines, consistent with post-coup suppression being driven by chilling effects rather than sustained network-level blocking.

2017-tanash-decline §4.1, Figures 2–3 evaluation

Comparing 5.6M pre-coup tweets (2015 Turkish general election) to 8.5M post-coup tweets (July–November 2016), the authors found 72% fewer government-censored tweets post-coup (142,492 vs. 513,719), with an estimated 43% of that decline attributable to reduced overall Twitter usage in Turkey and the remainder to user self-censorship.

2017-tanash-decline §4.1 evaluation

Twitter's official Transparency Report for July–December 2016 reported 489 censored tweets in Turkey from non-withheld accounts; the authors identified 6,402 unique censored tweets from the same period—approximately 13× more than officially reported—replicating an earlier order-of-magnitude undercount finding by Tanash et al. (2015).

2017-tanash-decline §5 evaluation

The northern Cyprus ISP Multimax (AS197792) employed IP-based blocking rather than DNS hijacking, and its blocked-site list — including Wikipedia, Tor Project, Wikileaks, and Psiphon — matched Turkish ISP blocklists rather than the RoC NBA gambling blocklist, demonstrating that geopolitically distinct ISP operators on the same island implement categorically different censorship regimes.

2017-ververis-internet §6.6 evaluation

The Encore system collected censorship measurements from 88,260 distinct IP addresses across 170 countries over seven months via installations by at least 17 volunteer website operators. China, India, the United Kingdom, and Brazil each contributed at least 1,000 measurements; Egypt, South Korea, Iran, Pakistan, Turkey, and Saudi Arabia each contributed more than 100.

2015-narayanan-no Introduction evaluation

Among withheld retweets in the Turkish dataset, 92% of the corresponding original tweets were also withheld, while 4% survived uncensored and 4% belonged to fully-withheld accounts; this asymmetry suggests the Turkish government's censorship targeting mechanism operates with some degree of systematic (possibly hashtag- or keyword-based) sweep rather than purely manual per-tweet review.

2015-tanash-known §5.2 (Phase III) detection

Manual review of 46 fully-withheld Turkish accounts found that 36 (78%) were classified as posting anti-government political content critical of President Erdoğan, 2 as pornography, 1 as advertising bots, 3 as unidentified, and 4 as no-longer-findable; NMF/tf-idf topic modeling of withheld individual tweets confirmed that the dominant censored themes were criticism of government-aligned media and ruling-party politicians.

2015-tanash-known §6.1, §6.2 evaluation

Twitter's country-withheld content mechanism relies on a browser-set location cookie, not IP geolocation; the authors confirmed that viewing a known-withheld Turkish tweet via a Turkish proxy server did not trigger the withholding display, but manually changing the Twitter app's location setting to 'Turkey' did — meaning any Turkish user who sets their location to a different country can bypass the entire withholding mechanism without Tor or a VPN.

2015-tanash-known §7 defense

The Chilling Effects database contained only 33 notices from Twitter across all countries, far fewer than the 108 account-withholding requests disclosed in Twitter's own transparency reports for the same period; Twitter itself acknowledges its transparency reporting is neither 100% comprehensive nor complete, and the authors confirmed that at least 86% of Turkish government withholding requests for non-protected tweets were approved by Twitter.

2015-tanash-known §3.1, §4.2 policy

Twitter's official transparency reports for Turkey recorded 183 withheld tweets (Jan–Jun 2014) and 1,820 withheld tweets (Jul–Dec 2014), but the authors' collection of 17 million geo-bounded Turkish tweets yielded 3,258 withheld tweets from the streaming phase alone, and expanding to followers of censored accounts produced 171,652 withheld tweets—roughly two orders of magnitude more than Twitter's own disclosures.

2015-tanash-known §4.1, §5.2 evaluation

Monitoring Twitter, YouTube, Tor, and Google Public DNS across 10 Atlas probes spanning 9 ASNs cost 19,200 credits per day (under 1 probe-day equivalent), and Atlas's external queuing allowed measurement scheduling to begin within hours of reported blocks. The platform documented 6 distinct shifts in Turkey's filtering strategy and identified private-sector cooperation in Russia that would have been missed by platforms limited to DNS and HTTP measurements.

2014-anderson-global §3.2, Table 3 evaluation

Turkey's filtering of Twitter relied overwhelmingly on DNS manipulation over IP blocking: as of April 24, 2014, only 167 IP addresses were blocked versus 40,566 domain names. Users who received valid DNS answers could browse Twitter without further interference, making foreign DNS servers (Google 8.8.8.8, OpenDNS) an effective circumvention mechanism — reportedly graffitied across Turkey in protest of the ban.

2014-anderson-global §4.1 detection

When Turkish users shifted to foreign DNS providers as a circumvention mechanism, Türk Telekom escalated by rerouting traffic destined for Google Public DNS (8.8.8.8 and 8.8.4.4) to a local DNS server serving false answers (Event E, March 28), causing a rapid drop in Tor and YouTube availability across all Atlas probes regardless of DNS configuration. At least 6 distinct shifts in filtering strategy were documented within a two-week period.

2014-anderson-global §4.1 detection

Across 11 countries, censorship execution falls into at least six distinct categories: DNS redirect to localhost (Malaysia, Russia, Turkey), DNS redirect with warning page (South Korea), connection timeout with no notification (Bangladesh, India), spoofed TCP RST injection (China), spoofed HTTP 403 with warning page (Bahrain, Iran), HTTP 302 redirect (South Korea, Thailand), and spoofed HTTP 200 iframe response (Saudi Arabia). Four countries censor at DNS and eight at routers, with South Korea employing both layers simultaneously.

2012-verkamp-inferring Table 3 evaluation

Over a 14-day evaluation in April 2011, CensMon tested 4,950 unique URLs from 2,500 domains across 174 agents in 33 countries, detecting 951 unique URLs from 193 domains as filtered. Manual verification of all 193 flagged domains found only 3 false positives, demonstrating high precision for an automated distributed monitor.

2011-sfakianakis-censmon §4.2 evaluation

The single Chinese PlanetLab node reported 176 censored domains — more than all other 173 agents combined. Turkey (6 domains), Jordan (5), and Hungary (1) were the only other countries with any detected filtering. 86% of agent nodes across 33 countries reported zero filtering events.

2011-sfakianakis-censmon §4.2, Table 2 evaluation

Open DNS resolvers, widely available across the internet as public services, make DNS poisoning trivially detectable globally: a researcher can connect to a resolver in a target country and compare responses against a trusted reference resolver, without requiring volunteer proxies or in-country infrastructure.

2011-wright-fine-grained §4.2 evaluation