Facebook Tor dark web
Facebook has lifted its ban on the anonymous browser Tor by launching its own .onion address. CC

Facebook has announced that users running the private web browser Tor will be able to access the social network for the first time through a secure ".onion" address.

Alec Muffett, a software engineer for security infrastructure at Facebook London, said in a blogpost on Friday that the decision to allow completely anonymous access is geared towards "giving people more confidence" when connecting to Facebook.

"It's important to us at Facebook to provide methods for people to use our site securely," Muffett said. "To make their experience more consistent with our goals of accessibility and security, we have begun an experiment which makes Facebook available directly over Tor network."

Tor (previously an acronym for The Onion Router) is a web browser that secures and encrypts connections to prevent government agencies, corporations or other unwanted third-parties from tracking the web activity of users.

It is often associated with the dark web, as it provides access to online black markets like The Silk Road 2 and Diabolus.

Dark web explained

The dark web is a section of the internet that is not indexed by search engines such as Google, and not easily navigated to using a standard web browser.

Accessing the dark web requires specialised knowledge and software tools. An example of this is content only accessible by using the Tor software and anonymity network, which while protecting privacy, is often associated with illicit activities.

An aspect of Tor's design means that users appear to be constantly switching locations, in a similar way to how a botnet attack may occur. To overcome this, Facebook adjusted issues with its own infrastructure to prevent Tor access being flagged as suspicious.

"Tor challenges some assumptions of Facebook's security mechanisms - for example its design means that from the perspective of our systems a person who appears to be connecting from Australia at one moment may the next appear to be in Sweden or Canada," Muffett said.

"(Facebook's) onion address connects you to Facebook's Core WWW Infrastructure (and therefore) provides end-to-end communication, from your browser directly into a Facebook datacentre."

Facebook has faced criticism in the past over its own privacy policies and its .onion address is the latest move in its attempts to address users' concerns. While it protects users from third-party surveillance, Tor access does not hide a user's identity from the social network itself.

"No, you're not anonymous to Facebook when you log in, but this provides a huge benefit for users who want security and privacy," said Runa Sandvik, a former Tor developer.

"You get around the censorship and local adversarial surveillance, and it adds another layer of security on top of your connection."