teredo.ipv6.microsoft.com off?

Tim Chown tjc at ecs.soton.ac.uk
Thu Jul 18 12:40:15 CEST 2013

On 18 Jul 2013, at 11:29, Phil Mayers <p.mayers at imperial.ac.uk> wrote:

> On 17/07/13 21:09, Brian E Carpenter wrote:
>> On 17/07/2013 19:13, Ignatios Souvatzis wrote:
>> ...
>>> Let me ask one thing... a couple of years ago, when I read the
>>> specification of Teredo, I was quite impressed by the details (If
>>> you accept the premise that you have to work around being jailed
>>> behind an IPv4 NAT) put into the protocol. One detail was that it
>>> is supposed to be lowest priority and so go automatically away
>>> (from the client end) as soon as some configued IPv6 is available
>>> on the link.
>>> Isn't that how it's implemented?
>> Yes, but the result is that the host tries to use Teredo preferentially
>> even if the IPv4 path is better; and if the Teredo path is broken
> That is the opposite of how it's supposed to work. Teredo addresses should be de-pref'd below everything else, and would thus only be used for connection to IPv6-only hosts if the host lacked other IPv6 connectivity.
> As someone else has pointed out, maybe it gets used for IPv6 literals, but not hostnames - the RFC 3484 table on windows ensures this.

Indeed; that's how it *should* be.


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