[tor-dev] Two features that would help load-balanced bridges

[Nick Mathewson]

On Wed, May 24, 2023 at 9:10 PM David Fifield <david at bamsoftware.com> wrote:
>
> Linus Nordberg and I will have a paper at FOCI this summer on the
> special way we run tor on the Snowflake bridges to permit better
> scaling. It discusses the two workarounds from the post below, namely a
> shim for predictable ExtORPort auth, and disabling onion key rotation.
> This setup has been in place on Snowflake bridges since January 2022.
> About 2.5% of Tor users (all users, not just bridge users) access Tor
> using Snowflake, so it's not a niche use case even if it's just us.
>
> One of the reviewers asked if there was a chance changes might be made
> in tor that make our workarounds unnecessary. Is there anything to say
> to this question? Might tor get a feature to control ExtORPort
> authentication or onion key rotation, or is something that's planned to
> stay as it is in favor of Arti? (Arti will probably remove the need for
> the load-balanced multi-tor configuration, which will also remove the
> need to disable onion key rotation, though better control over ExtORPort
> auth could still be useful for running server PTs that are not child
> processes of arti.)

I can't speak definitively about the plans for the C tor
implementation. My understanding is that they are hoping to keep new
features there to a minimum, so I don't know if this would be
something they can do.

In Arti, we're a lot more open to that kind of stuff. We're not
planning to start a relay implementation till next year at the
earliest, but please remind us when we start working on ExtOrPort and
related things and we can try to figure out a design that works.