In this fourth Tor article, I will quickly cover how to run a Tor relay, the Tor project already have a very nice and up-to-date Guide for setting a relay. Those relays are what make Tor usable, with more relay, Tor gets more bandwidth and it makes you harder to trace, because that would mean more traffic to analyze.
A relay server can be an exit node, which will relay Tor traffic to the outside. This implies a lot of legal issues, the Tor project foundation offers to help you if your exit node gets you in trouble.
Remember that being an exit node is optional. Most relays are not exit nodes. They will either relay traffic between relays, or become a guard which is an entry point to the Tor network. The guard gets the request over non-tor network and send it to the next relay of the user circuit.
Running a relay requires a lot of CPU (capable of some crypto) and a huge amount of bandwidth. Running a relay requires at least a bandwidth of 10Mb/s, this is a minimal requirement. If you have less, you can still run a bridge with obfs4 but I won’t cover it here.
When running a relay, you will be able to set a daily/weekly/monthly traffic limit, so your relay will stop relaying when it reach the quota. It’s quiet useful if you don’t have unmetered bandwidth, you can also limit the bandwidth allowed to Tor.
To get real-time informations about your relay, the software Nyx (net/nyx) is a Tor top-like frontend which show Tor cpu usage, bandwidth, connections, log in real time.