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I moved my Tor exit relay from my main server to a dedicated Raspberry Pi a week or two ago, and while it seemed to run fine at first it's been crashing a lot lately.

I made the heartbeat more frequent and checked the logs, and it looks like after a reboot the relay runs fine with ~150 open circuits for about 12 hours, then suddenly jumps up to 600 open circuits, prints a bunch of Your computer is too slow to handle this many circuit creation requests! errors and then crashes.

I tried overclocking the Pi, upping the MaxOnionsPending to 250, and reducing the MaxAdvertisedBandwidth to 250KB, and none of those seemed to help. An email thread I saw speculated that this happens "when your relay becomes the hidden service directory, or introduction point, for a popular hidden service."

Does anyone have any ideas how to fix this? People who are running relays on Raspberry Pis, have you seen this or know how to deal with it?

  • What is your current exit policy? I noticed such log messages when my policy was too open (allowed too many ports). – Jens Kubieziel Jan 21 '14 at 7:42
  • Interesting...my exit policy only allows outbound ports 80 and 443. Right now I'm running it as a relay only (no exiting) to see if that affects the problem. – Alex Ryan Jan 21 '14 at 17:30
  • How did your relay work in the meantime? Do you still encounter those messages? – Jens Kubieziel Jan 24 '14 at 10:05
  • The circuit creation storms seemed to go away when I turned off exiting. – Alex Ryan Jan 25 '14 at 10:36
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I've found a simple solution - it seems this problem only appears on 0.2.3.x. After upgrading to 0.2.4.x, the problem went away completely. Incidentally, the CPU usage efficiency seems to have been drastically improved in the new version.

This is still somewhat problematic, as Tor in the standard Raspbian repos is still at 0.2.3.25. Fortunately, it's easy to compile 0.2.4.20 from source according to the instructions here.

  • Does anyone know who to talk to about getting Tor up to date in the repos? – Alex Ryan Jan 25 '14 at 10:35
  • weasel, who is the maintainer of Debians version of Tor, wrote some longer description in his answer. He explains why you have to compile it for yourself at the moment. – Jens Kubieziel Jan 25 '14 at 10:48
  • I saw that - he said "If you want to run newer Tor versions than are available from the Raspbian folks, you will have to build them yourself." I'm wondering who "the Raspbian folks" are and if we can ask them to update the version of Tor that they currently have in their repos. – Alex Ryan Jan 25 '14 at 22:49
  • I gues the Raspbian folks are the developers listed here: raspbian.org/RaspbianTeam?highlight=%28contact%29 – Jens Kubieziel Jan 26 '14 at 9:42

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