[tor-relays] About relay size

[teor]

On 3 Oct 2017, at 03:07, Scott Bennett <bennett at sdf.org> wrote:

>>> In the meantime, I think it would be great to have IPv6-only relays, to
>>> avoid this kind of NAT-related issues.
>> 
>> We'd love to make this happen, but the anonymity implications
>> of mixed IPv4-only and IPv6-only (non-clique) networks need
>> further research. Search the list archives for details.
>> 
>     Couldn't that be taken care of in the tor client code?  For example, a
> client, having chosen a path through which an IPv6-only relay, could extend
> the path by one hop to tunnel through a node with both types of interface
> published?

Yes, clients choose paths, and could choose them using these kinds of
restrictions. But current tor relay versions won't extend to other relays
over IPv6. Because we don't understand the anonymity implications of
restricting the next relay in the path based on the previous relay. Which
is why we need further research.

> A related question is can a relay with only an IPv4 address
> published currently set an IPv6 OutboundBindAddress?

Yes. This is useful for IPv6 exits without a fixed IPv6 ORPort address.

T