teredo.ipv6.microsoft.com off?

Phil Mayers p.mayers at imperial.ac.uk
Thu Jul 18 12:29:31 CEST 2013

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 

As someone else has pointed out, maybe it gets used for IPv6 literals, 
but not hostnames - the RFC 3484 table on windows ensures this.

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