Internet service providers in Turkey have been intercepting traffic to Google’s DNS servers and redirecting it, shutting off a workaround that Turkish users had employed to get to sites such as Twitter and YouTube after the government had blocked them.
Google software engineers said they had received credible reports over the weekend about the traffic interceptions, and they had looked into the situation and confirmed the problem themselves. Google operates free DNS servers to help accelerate Web traffic, and its engineers said that Turkish ISPs have set up their own servers that are imitating Google’s.
“Google operates DNS servers because we believe that you should be able to quickly and securely make your way to whatever host you’re looking for, be it YouTube, Twitter, or any other,” Steven Carstensen, software engineer at Google, wrote in a blog post.
“But imagine if someone had changed out your phone book with another one, which looks pretty much the same as before, except that the listings for a few people showed the wrong phone number. That’s essentially what’s happened: Turkish ISPs have set up servers that masquerade as Google’s DNS service.”
Turkish authorities last week began blocking sites such as YouTube and Twitter, saying that there was information on those sites that was harmful to the country’s national security. The Tor service also was blocked in Turkey at certain points last week. One method for blocking a site is for ISPs to redirect requests for those sites to other destinations. Users in Turkey noticed the problem and began working around it by using other DNS servers, including those run by Google.
If ISPs in Turkey are intercepting traffic to Google’s DNS servers, that means that ISPs or the government can redirect those users to whatever site they choose. DNS hijacks sometimes are used by attackers as part of larger attacks, and intercepting DNS traffic also has become a common tactic for governments in some countries that are trying to prevent citizens from reaching certain sites, often social media networks.
Google officials did not say whether they have taken any steps to address the situation in Turkey.
Image from Flickr photos of Bob Mical.