Russia Wants to Block Tor, But It Probably Can't

​The Russian government said last week it wants to ​ban Tor, a browser and network that anonymizes web traffic, but how likely is it that they will succeed at censoring a tool that is itself used to circumvent censorship?

Certain domains have been blocked in Russia since 2012, when a blacklist law went into effect, but the current legislation relies on individual internet service providers to block these sites. Many citizens easily bypass the barriers with tools like Tor and VPN, or virtual private network, services, which allow them to tunnel traffic through alternative IP addresses and appear as if they are located outside of Russia.

Vadim Ampelonskogo, the chief press officer for the country's federal authority on telecommunications, released a st​atement describing Tor as, "den of criminals" and "ghouls, all gathered in one place." He made it clear the government has the service in its sights, saying blocking it would be difficult but "technically possible."

According to Jillian York, Director for International Freedom of Expression at the Electronic Frontier Foundation, it is unlikely Russia would follow through on such a massive undertaking. While VPNs are fairly easy to block, Tor is a different game.

Governments can block access to VPN services by blocking access from IP addresses linked to VPN providers. Blocking Tor is more complex, and requires identifying and blocking the destination nodes traffic travels through rather than the URL or IP address.

"There are a number of countries that block VPNs, including Saudi Arabia, Bahrain, Iran and China," she said. "But the only country to successfully block Tor is China."

That's because China's internet is fundamentally different. While internet in China has been intensely controlled from its beginnings, Russia's was not designed with such broad censorship in mind.

Information security consultant Nik Cubrilovic said Russia has a harder time blocking sites than China because few sites Russians use are actually hosted in Russia. Out of the 20 top sites in Russia, only three of them are actually hosted there.

"There might be a case here of disconnect between what Russian MPs believe they can do because they've seen China do it, and what they can actually do when their network is set up in a way that won't allow it," Cubrilovic said.

Cubrilovic said the government could also block the download page for Tor, but there are a plethora of mirror pages in place that people could access instead. In fact, Tor has now built in extra measures for users who install it in countries seeking to block the service.

If you click the "censored" option, the Tor installer will prompt you to use either a built-in obfuscation protocol and network, or your own list of bridges, additional Tor relays not listed in the main directory, obscuring your traffic even further.

"The effect of blocking on that is close to zero," he said, adding that these tools are designed to make it difficult to distinguish from normal traffic. One new obfuscation protocol called Meek makes it difficult to distinguish user traffic from ordinary traffic to sites like Google and Amazon and even works in China.

Even if Tor is difficult to block, York said Russia is likely to block VPNs soon.

"It's clear they're going to start taking these measures, and web proxies are going to be the first to go because they're easy to block," she said. "The capability is already there, so it's more of a legal matter at this point."

Cubrilovic said the government's attacks on VPN services may actually shift more traffic to Tor, which is currently used by 150,000 Russians daily, according to the Tor Proj​ect.

"Blocking VPN services for censorship reasons isn't always a bad thing when it drives people to the alternative which is better censorship technology like Tor," he said. "It's an excellent evangelizing job they're doing letting people know Tor exists and they're finding it hard to block."

Correction: An earlier version of this article incorrectly used a photo of Polish police. It has been changed to one of protesters in Moscow.