The Onion Router allows users to keep their browsing, online posting, instant messaging and other online communication anonymous by directing Internet traffic through a worldwide volunteer network of thousands of relays, and is often used by users that want to protect their freedom and privacy.
That usually means dissenters in autocratic countries, but following the recent revelations about the existence of PRISM, it is increasingly being used by citizens of Western countries. Unfortunately, Tor's ability to make people anonymous online is also often misused by cyber crooks.
The Tor team has reacted to the blocking pretty quickly, working with Facebook to remedy the situation and reassuring users that Facebook was not blocking Tor deliberately.
"A high volume of malicious activity across Tor exit nodes triggered Facebook's site integrity systems which are designed to protect people who use the service," they wrote in a blog post, following up later with an update that explained / confirmed that "automated malicious activity coming from a significant number of Tor exit nodes" was the reason for access to Facebook having been suspended, and that the issue has been finally resolved.
While both organizations were quick to react, this incident has proved that with the current political
situation around the world, the need for anonymity networks such as Tor is, unfortunately, on the rise.
After the start of the Turkish Gezi park protest, Turks have turned en masse to AnchorFree Hotspot Shield, a free VPN service, but here are many more alternatives, and tips on how to choose a good one.