On killing IPv6 transition mechanisms

Tim Chown tjc at ecs.soton.ac.uk
Tue Mar 16 16:37:57 CET 2010

On Tue, Mar 16, 2010 at 04:03:20PM +0100, Tore Anderson wrote:
> Hi Gert,
> > Oh, good point.  Yes, it seems to be enabled-by-default, and since
> > the operating system on the client system does not *know* that it's
> > 6to4 (for the client, it's just "IPv6 that someone announced a RA for
> > on the local LAN"), it can't properly (de-)prioritize it...
> Actually, an RFC 3484-compliant getaddrinfo() implementation should be
> able to determine that, since it looks at its own source IP address used
> ...
> Hmmm...  It seems Mac OS X isn't RFC 3484-compliant, or that Safari and
> Firefox don't use getaddrinfo() on that platform (of those 1816 hits,
> 1374 are Safari and 442 Firefox).  Wonder how the hell I could have
> missed this earlier...

Indeed, using 6to4 behind an Airport box on a Mac is not good.  Which
is probably why the default changed.   But Apple get on with 3484 please.

Also Mac OSX still seems to have the DNS bug/feature whereby it asks
for A and AAAA records but throws away responses after the first, so
you may not ever see IPv6 used for some destinations.   

Then don't get started on DHCPv6 or SSM on Macs (and despite that I
do use two at my place of work ;)

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