Re: RFC3484 destination address selection rule 2 is buggy

[Mohacsi Janos <[e-mail]>]

On Fri, 14 Mar 2008, Rémi Denis-Courmont wrote:

> Le Friday 14 March 2008 00:27:26 Pekka Savola, vous avez écrit :
>> This issue was first reported about 5 years ago by Alain Durand et al and
>> yet there is no fix yet (and no mention in the default address selection
>> problem statement), see section 2 of:
>> http://tools.ietf.org/html/draft-ietf-v6ops-v6onbydefault-03
>>
>> The main problem is destination address selection rule 2 which requires
>> that source and destination address scopes must match (which in the case of
>> v4 private and global addresses is not a very useful comparison given the
>> prevalence of NAT).
>
> Indeed. And this was (inconclusively) discussed at the mike during the last
> v6ops meeting. I had also asked about this a few months ago. Nobody seemed to
> care (winter vacation?):
> http://www.ops.ietf.org/lists/v6ops/v6ops.2007/msg01150.html
>
>> Maybe we need a more systematic approach to deal with RFC3484 issues (as
>> in, a numbered list of all the problems noted) instead of doing a nice new
>> features to have PPT slideshow every IETF meeting.
>
> I think we need to "simplify" RFC3484 section 3.2 through removing the IPv4
> site-local scope there: we'd be left with only global scope (public addresses
> + RFC1918) and link-local scope (169.254.0.0/16).
>
> I suspect some implementors (at least Windows) already ignore §3.2 for the
> sake of reliability. I know Linux does implement ?3.2 to the letter of the
> RFC unfortunately. And I have seen people _remove_ AAAA from their server's
> DNS records because of this issue, combined with deficient 6to4 relays.
>
>
> Another problem involves incomplete implementation of RFC3484: some stacks
> apply RFC3484 for IPv6, in connect() and sendto() socket APIs, but fail to do
> RFC3484 in getaddrinfo(), and simply assume IPv6 is first, and IPv4 second. I
> suspect this applies to OSX and BSDs, and also "embedded" C run-times.

Not exactly. The opensource BSD implementations has "proper" RFC 3484 - 
they are treating RFC1918 addresses as global scope.

http://www.ops.ietf.org/lists/v6ops/v6ops.2007/msg01151.html

Unfortunately OSX does not have any RFC 3484 implementation.... I reported 
few months ago to Apple this issue.....

Best Regards,
 		Janos Mohacsi

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