On Sat, Jul 07, 2007 at 10:54:50AM -0700, coderman wrote: > apologies for formatting; available at > http://peertech.org/pub/tor-ipv6-exit-proposal.txt if this is > unreadable. > > --- > > Proposal : IPv6 exit Added as proposal 117, and re-wrapped to fit in 80 columns; thanks! [...] > It should be noted that IPv4 mapped IPv6 addresses are not valid > exit destinations. This mechanism is mainly used to interoperate > with both IPv4 and IPv6 clients on the same socket. Any attempts > to use an IPv4 mapped IPv6 address, perhaps to circumvent exit > policy for IPv4, must be refused. Alternatively, we could just apply IPv4 exit policies to IPv4-mapped IPv6 addresses. Would that be cleaner? [...] > 1.3. DNS name resolution of IPv6 addresses (AAAA records) [...] > All routers which perform DNS resolution on behalf of clients > (RELAY_RESOLVE) should perform and respond with both A and AAAA > resources. Hm. We need some way to do this inside the current relay_resolve format without confusing existing clients. [...] > 3. Questions and concerns > > 3.1. DNS A6 records > > A6 is explicitly avoided in this document. There are potential > reasons for implementing this, however, the inherent complexity of > the protocol and resolvers make this unappealing. Is there a > compelling reason to consider A6 as part of IPv6 exit support? I'm okay doing nothing with A6 for now. [...] > 3.3. Support for IPv6 only clients > > It may be useful to support IPv6 only clients using IPv4 mapped IPv6 > addresses. This would require transparent DNS proxy using IPv6 > transport and the ability to map A record responses into IPv4 mapped > IPv6 addresses. The transparent TCP proxy would thus need to detect these > mapped addresses and connect to the desired IPv4 host. > > The relative lack of any IPv6 only hosts or applications makes > this a lot of work for very little gain. Is there a compelling > reason to support this capability? I'd like to add support for ipv6-only clients, but I think that's a separate proposal. yrs, -- Nick Mathewson
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