[tor-relays] Tiny computers (RPi-like) for exit nodes?

Michael McConville mmcco at mykolab.com
Thu Aug 18 17:50:33 UTC 2016


Michael McConville wrote:
> Roman Mamedov wrote:
> > On Thu, 18 Aug 2016 10:40:00 -0600
> > Michael McConville <mmcco at mykolab.com> wrote:
> > 
> > > Zack Weinberg wrote:
> > > > Has anyone had any experience running *exit* nodes on Raspberry
> > > > Pi-grade hardware, or slightly beefier?  We are thinking of
> > > > replacing the old, bulky, power-hungry machine currently running
> > > > exit 78C7C299DB4C4BD119A22B87B57D5AF5F3741A79 with something on
> > > > that level. It only has to hit 10Mbps.
> > > 
> > > There's only one way to find out, but I suspect an RPi would be
> > > too weak for the job. Exits use more CPU because they manage far
> > > more TCP/UDP connections than a non-exit relay. I've seen
> > > significant CPU usage (maybe even CPU saturation) on a cheap Intel
> > > Core Duo moving about 3-5 MB/s.
> > 
> > Raspberry Pi 3 should do fine, not to mention some of the more
> > powerful boards -- there are now up to 8-core, up to 1.7 GHz ones.
> > Even though the core number won't help you too much, you shouldn't
> > underestimate what a modern 64-bit ARM can do. Especially if the
> > task at hand is mere 10 Mbps.
> 
> I'd be happy to be proven wrong. However, remember that while 10 Mbps
> doesn't sound like a lot, it can imply 7,000+ open connections. That
> can stress the kernel and the CPU cache.

I forgot to mention all the crypto required, too. These boards don't
have crypto accelerators, so that's a big cost.


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