Turkey strengthens Twitter ban, institutes IP level block

A Turkish national flag with the word 'offline' projected on it, is seen through a Twitter logo in this photo illustration taken in Zenica, March 21, 2014. Turkey's courts have blocked access to Twitter a little over a week before elections as Prime Minister Tayyip Erdogan battles a corruption scandal that has seen social media awash with alleged evidence of government wrongdoing. The ban came hours after a defiant Erdogan, on the campaign trail ahead of key March 30 local elections, vowed to
(Reuters/Dado Ruvic)

After Turkish Prime Minister Recep Tayyip Erdogan banned Twitter in the country late Thursday night, many local users found ways to circumvent the restrictions. But getting around the ban is becoming more difficult, as the government appears to have changed up its technical strategy for blocking the social media platform.

When the block was first implemented, most Internet Service Providers appeared to be using DNS redirects to show users inside Turkey a page citing various court orders Twitter had not responded to as justification for the ban. DNS, or the Domain Name System, is sort of like a phone book for the Internet -- it translates a URL into the numbers of IP addresses so browsers can access the Internet. Local ISPs were essentially changing the record in their digital phone books and redirecting many people in Turkey who were attempting to access Twitter to a different destination.

But this redirection could be circumvented by changing the record manually and relying on a different DNS server. In Turkey, many users turned to public DNS servers, including some operated by Google -- in fact, the records for those DNS servers ended up in protest graffiti widely shared online. But earlier Saturday, the local Hurriyet Daily News reported that most, if not all, DNS options were blocked -- including Google's.

And now, researchers are reporting that Twitter is blocked at the IP level within Turkey. Collin Anderson, an independent researcher who has been following the situation in Turkey, said he saw the ban roll out over the course of two hours Saturday. Beginning around 1 p.m. UTC, his measurements of Turkish ISPs began to report not being able to reach IP addresses associated with Twitter's Web server. "By 15:00 UTC, no ISP could reach Twitter by IP address any longer."

Earlier in the day he saw a similar pattern with Turkish ISPs blocking DNS services. He believes the fragmented nature of the rollouts implies that the ISPs received a court of administrative order they complied with at their own rates. The DNS blocking started between 1 a.m. and 2 a.m. UTC, but was removed across all ISPs between 5 a.m. and 6 a.m. UTC, according to his research.

Internet monitoring company Renesys also reported that Twitter IP addresses were now blocked in Turkey, tweeting out this graphic:

 

When sites are blocked by IP address, simply changing the DNS record will no longer solve the problem. But there are some workarounds. Using a Virtual Private Network to digitally tunnel outside the ban should still allow those in Turkey to bypass the block. And the anonymous browsing tool Tor, which works by rerouting traffic through nodes on a network that spans the globe, should also enable users to circumvent the ban.

But both of those options are slightly more technically involved than the previously available ways to bypass the block. Presumably, Tweeting via SMS has not been affected by the IP block.

While Erdogan seems to have hoped that blocking the social network would dilute its local power, since the "ban" Twitter usage within Turkey actually exploded.

Andrea Peterson covers technology policy for The Washington Post, with an emphasis on cybersecurity, consumer privacy, transparency, surveillance and open government.
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