[tor-relays] About relay size

[teor]

> On 3 Oct 2017, at 10:57, Roman Mamedov <rm at romanrm.net> wrote:
> 
> On Tue, 3 Oct 2017 09:53:46 -0400
> teor <teor2345 at gmail.com> wrote:
> 
>>>    For interposing dual-protocoled nodes along the way, how many do there
>>> have to be for it to become "not too limiting"?
>> 
>> This is one of the questions we need researchers to answer.
> 
> I can't help but feel you are overcomplicating this.
> 
> Clients create a circuit by randomly picking 3 nodes out of the all-nodes
> pile, right? If all 3 happen to be IPv6-capable, then the circuit can go over
> IPv6 and all is fine. If some of the 3 happen to be IPv6-only while others are
> IPv4-only, the whole selection can be thrown away and repeated.
> 
> That way IPv6-only relays could get some usage on a totally random basis, with
> no compromises and no restraining "of the next hop based on the previous one",
> not hurting anonymity. Clients just need to know which nodes are IPv4-only,
> IPv6-only or dual-stack, to not attempt unworkable combinations, discarding
> them instead.

Discarding unworkable combinations and restraining node choices seem
equivalent to me, although the relay weights may be different.

> And as there are more and more dual-stack or IPv6-only relays, the "throw
> away" step will be needed less and less often.

If you think this will work and is safe for client anonymity, then the next step
is to write a tor proposal. Having a concrete design could help with
analysing the anonymity implications as well.

I think IPv6-only relays are a lower priority than better IPv6 and dual-stack
client support, and IPv6-only bridge support  But we could do both in the
same release.

Tim