If I want to create a bunch of Tor relays running Linux with various VPS providers and want to save on cost, what is the minimum hardware config that I can get away with while still effectively relaying traffic?

  • Keep in mind, running a[n exit] relay is not without it's massive, crippling downsides - be sure to have SOA records pointed to your IP reverse :) – Amelia Sep 25 '13 at 20:05

A lot of us are running on Raspberry Pi. Almost every hardware setup can handle some amount of traffic. One just dials down the amount of bandwidth one is willing to advertise or accept in the configuration file.

There are a whole range of relay capabilities. You can see a list of their bandwidths at http://torstatus.blutmagie.de/. The fastest relays obviously have fiber connections and enough RAM and CPU to handle the traffic.

You can monitor your node to see if it is getting crushed by the amount of traffic it is receiving. My Raspberry Pi is able to qualify as a fast exit node, handling about 200KB/s. In this case, the machine is CPU constrained. For other setups, they are bandwidth constrained.

The Pi has 512 MB RAM and the processor is by ARM. The whole machine draws less than 5 Watts, about what a nightlight draws. And it is very stable.

  • What are the specs on a Raspberry Pi (and is it actually good; people are doing it, but that doesn't mean it's a good idea)? What makes a good relay (RAM, bandwidth, CPU, etc.)? This could use some more info. – Sam Whited Sep 25 '13 at 19:33
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    I'm working on Tor-on-Raspberry-Pi as much as I can in my spare time, and I can add a little bit. The model B comes with 512MB RAM and an old, old ARM CPU that you should probably overclock to about 900-950MHz. The biggest problems you will run into currently with Tor on Pi (and teeny VPS): RAM; RAM consumed by TCP sockets; CPU blocking; and you really should install Tor 0.2.4.x on the RasPi, not 0.2.3.x. But RAM, for now, is typically the biggest problem if bandwidth isn't an issue. – Gordon Morehouse Sep 29 '13 at 17:46
  • I do have some .debs for the Pi up, and pointers to instructions if you don't trust .debs of anonymity software from random dudes on the Internet. github.com/gordon-morehouse/cipollini – Gordon Morehouse Sep 29 '13 at 17:47
  • Over the past 9 months, the bottleneck for the Raspberry Pi seems to have shifted from RAM to CPU. Running a recent git version (2.5.4-alpha-dev), I'm seeing my CPU hit 100% while memory remains stable at 25%. That said, when bandwidth is the bottleneck (sub-300KB/s), it is ideal in the sense that it is easy to set up and requires very little power. – Joost Jun 27 '14 at 14:38

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