It is time to expand the Tor network

[Roger Dingledine <arma@xxxxxxx>]

Hi All,

I've been pondering how to deal with the recent Bittorrent load. Here's
one answer.

First, let's consider what Tor is for. Tor is designed to improve
privacy for certain activities. These activities include pulling down
or publishing news web pages; instant messaging; talking on irc. They
don't include entire protocols (like http), or activities like pulling
down huge files. (We wouldn't mind providing that ability, but forced
to choose, we prefer protecting the former activities.)

Because Tor clients now pick nodes for their path proportional to the
advertised capacity of each node, we already do basic load balancing. This
means we can accept nodes with a capacity of only 15kB or 20kB, and
they'll be used sometimes but rarely, which is exactly what we want. So
far we've been preferring not to take these nodes, because we wanted to
give clients lots of throughput, and because these nodes tend to come
with higher latency, less reliable uptimes, and crummier networks --
degrading overall user experience for every activity.

If we expand the network to include them, though, then we'll end up
with a lot more nodes to choose from (which also happens to be good for
anonymity). The chances increase that a given connection that BT tries
will not have much throughput available -- which means that if the BT
folks stick around, as we add more thin pipes, the chances increase
that a given connection will be overloaded and thus provide crummy
service. Oh well.

A rephrase of my plan could be "we will make Tor so slow that the file
sharers will go away." But remember that if this keeps up, all our fat
connections will appear like thin ones anyway, so this may not be as
radical a change as it sounds.

Alas, as we go in this direction, we will hear fewer shocked statements
from former JAP and Anonymizer users wondering how Tor can be so fast.
But we've been adding the infrastructure to handle this, and now is
the time. I've changed the documentation for setting up servers --
http://tor.freehaven.net/doc/tor-doc.html#server -- to reflect this
change. If you're on cable or dsl and have been waiting to run a node,
now's the time. :)

Thanks,
--Roger