The Tor anonymity network is an invaluable tool for journalists, whistle-blowers, political dissidents, and anyone who values their privacy on the internet.
Tor anonymises individuals by routing their internet signal though at least three ‘relays’ (also known as nodes), which are run by volunteers. The more of these volunteer relays that are available, the faster and more stable the Tor network will run.
‘Middle relays’ simply pass Tor traffic from either the end-user or a middle relay to another middle relay or and end relay. Volunteering to run one incurs very little no risk, as even if a user is doing something illegal, the IP address of a middle relay does not show up as the source of the traffic.
Volunteering to run an ‘exit relay’ is somewhat dicier proposition, as traffic leaves the Tor network and enters the regular internet through these nodes. The volunteer’s IP address therefore appears to be the source of the traffic, and the volunteer could be flagged up by law enforcement or intelligence organizations, and could conceivably take the blame for other users’ actions.
Because of this, there are relatively few exit nodes, which means that publically listed ones can be fairly easily blocked by countries such as China. ‘Bridges’ are a special form of middle relay designed to help combat this, and can also be run by volunteers.
The first Tor Challenge was held by the Electronic Frontier Foundation in 2011 during the Arab Spring with the aim of educating people about the value of Tor, and encouraging those interested in promoting freedom and privacy online to strengthen Tor by volunteering running Tor relays (volunteers can chose which type of relay they would like to run).
The original Challenge achieved 549 participating relays, but this year over 1000 people helped bring the total number of participating relays up to 1,635, strengthening the Tor network and helping Tor users everywhere. Most importantly, the number of exit relays more than doubled from 123 to 326. Well done volunteers!