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Re: 6to4 using ::FFFF:0000:0000/96 (mail.comcast.net AAAA record weirdness)
On Mon, Jan 28, 2008 at 11:17:47AM +0100, R?mi Despr?s wrote:
> >>1. The RFC on Basic Socket Interface Extensions for IPv6 (RFC 2553)
> >>states in its section 3.7:
> >><< Applications may use PF_INET6 sockets to open TCP connections to IPv4
> >> nodes, or send UDP packets to IPv4 nodes, by simply encoding the
> >> destination's IPv4 address as an IPv4-mapped IPv6 address, and
> >> passing that address, within a sockaddr_in6 structure, in the
> >> connect() or sendto() call. >>
> >How important is this feature in practice? Could we deprecate it?
> IMO deprecating it would be a bad step backward!
Yes - there is a (reasonable) school of thought that says that
draft-itojun-v6ops-v4mapped-harmful missed the mark, and that it
is actally better to write server applications to use a single
socket to accept both IPv4 and IPv6 clients. You then always use
mapped addresses to represent IPv4 addresses in ACLs/firewalls/...
Deprecating this would make life harder for people who have chosen
this model of managing dual-stacked applications.