Tor, a popular online anonymity tool used by many Iranians to bypass Internet censorship, was blocked from late July until the beginning of August. The block prevented 75 percent of the network's estimated 40,000 daily users in Iran from connecting to Tor.
The Iranian government periodically releases new filtering rules intended to block Tor traffic, to which the Tor community typically responds with a same-day antidote for the block.
Tor has been of particular sensitivity since it was widely used by activists, protesters and citizen journalists during the 2009 Green Movement. The software, used by digital activists worldwide, allows users to reach their target website by tunneling through a network of intermediary servers, a process that anonymizes the users along the way and makes their identities indecipherable for ISPs, thus allowing them to circumvent government-imposed censorship. Tor is an open source software and has a large community of users and developers who work to detect and eliminate security flaws and bugs, along with filtering by governments.
On July 30, the Tor project reported users couldn't access regular Tor connections in Iran. Tor metrics also showed a drop in the number of users connecting to the service on a daily basis.