Re: TOR and offensive content

[Roger Dingledine <arma@mit.edu>]

On Tue, Mar 16, 2004 at 08:45:58PM -0500, Niels Provos wrote:
> On Wed, Mar 17, 2004 at 12:42:16AM +0000, Jason Holt wrote:
> > I know that freedom from censorship is a fundamental principle of anonymizing
> > systems, but if people wouldn't mind minimizing casual pr0n-surfing via TOR,
> > it'll make my life easier.  The net admins have actually been quite
> > understanding about the outgoing traffic from my server node, but will
> > probably shut me down if it becomes excessive.

Jason, by "excessive" do you mean "lots of porn surfing", or do you mean
"lots of bytes used"?

> You could identify the servers that are used to download port from and
> remove them from your exit policy.

Yes, this is a perfectly friendly and simple way to disallow exiting to
certain sites while still generally allowing outgoing traffic. Clients
with a certain destination in mind will automatically look at your exit
policy and choose a different exit node.

> and bandwidth limit your node.

This solution is a bit trickier. Tor also supports built-in bandwidth
limits (though Niels is right to trust his software more -- its only
goal in life is to limit bandwidth, so it probably does it better).

But right now the Tor clients don't have any way to take into account that
a given server won't provide them much bandwidth. The best answer I've
got right now is to ask all the servers to allow at least 100 kilobytes
each way, and if they can't do that, they shouldn't be servers, at least
until we've come up with a way to handle the issue.

I'd love to see a design for a path selection algorithm that takes into
account available bandwidth, without introducing a lot of messy overhead
in the protocol, and without endangering anonymity much.

Thanks,
--Roger