[tor-dev] Scaling tor for a global population

Mike Perry mikeperry at torproject.org
Sun Sep 28 03:45:15 UTC 2014

Fabio Pietrosanti (naif):
> Il 9/27/14, 2:33 AM, Mike Perry ha scritto:
> >
> > We could also handle controlled rollouts to fractions of their userbase
> > to test the waters, and slowly add high capacity nodes to the network to
> > support these new users, to ensure we have the people ready to accept
> > payment for running the servers, and maintain diversity.
> I read your very detailed estimations and improvement paths, i love it!
> However i see that the main suggestion to increase the "network
> capacity" can be simplified as follow:
> - improve big nodes ability to push even more traffic
> - add more big nodes
> Other improvements are to reduce the "consensus size" and "directory
> load", but not specifically on network capacity.
> While this is the obvious way to "add more capacity" i feel that's going
> to have impacts such as:
> 1) reduce the "diversity" (thus the anonymity, because few players will
> handle most of the network's traffic)
> 2) make it "irrelevant" for anyone to run their own small/volounteer relay
> That sounds like the "easier way" to scale up in a defined amount of
> time and with a defined budget, but imho also with consequences and
> pre-defined limits.
> I feel that the only way to scale-up without limits and consequences is
> to have end-users became "active elements" of the network, where we have
> success story such as Skype.
> End-users have important network resources available that can be
> estimated and used (with care).
> Not all end-users are equal, i'm now on a 2M Hyperlan line (damn digital
> divide!), but someone else in Stockholm or San Francisco it's on a
> 1000M/100M fiber connection @home (not in a datacenter) and while in
> Milan i've a 100M/10M fiber!
> That bandwith resources are amazing, usually quite cheap (home broadband
> lines), widely available in the end-users hands.
> IMHO those are the bandwidth resources, widely available, cheap, very
> diverse/sparse that could help the Tor network to scale-up.
> How to use it properly within/for the Tor network? That's a different topic.

It's the same topic: I'm arguing that we want to use the 100M fiber
connection, and maybe the 10M connection, but definitely not the ADSL
link with only 256kbit upstream. The latter costs more bytes to tell
clients about than it contributes to the network.

We can cut these ADSL relays from the network and turn them into bridges
using the bandwidth authorties. Or have the default relay mode be to
start as a bridge and get promoted to a relay once you are measured.

As for diversity, we can better achieve diversity through proper network
allocation based on the current node selection algorithms and load
balancing, so we actually know that our desired percentage of traffic is
going through the geography/jurisdictions/organizations we want.

Keeping thousands of junk nodes that only carry a tiny fraction of the
Tor network capacity just so we can pretend we have diveristy is no
solution. It's wishful ostrich thinking.

Slow/junk home nodes also have worse mix properties than fast nodes, due
to less concurrent traffic running through them. They are thus more
useful to surveil externally for correlation, and probably also easier
to compromise.

Mike Perry
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