Teredo source addresses from 6to4 relay

Remi Denis-Courmont rdenis at simphalempin.com
Wed May 16 11:04:14 CEST 2007

On Wed, 16 May 2007 09:13:16 +0100, David Malone <dwmalone at maths.tcd.ie> wrote:
> On Fri, May 11, 2007 at 11:44:47AM +0200, Remi Denis-Courmont wrote:
>> What you would need there is source routing. Better yet understand why
>> RFC3484 is not applied properly...
> Well, FreeBSD 4 behaved (roughly) as if it had RFC 3484 but with
> an empty policy table.

I am not aware of any Teredo implementations for FreeBSD 4, though.

> The default policy has no mention of Teredo. I wonder what the
> pros and cons of adding an entry for 2000:0000::/32 to treat Teredo
> in a similar way to 6to4 would be?

That is required, since Teredo is defined as a last-resort. In RFC3484, that
can only occur if it defined as a different label with low precedence. Teredo
is absent from RFC3484 only because it predates Teredo (RFC4380).

In practice, Teredo-capable Windows IPv6 stacks, Linux kernel (>=
and glibc (> 2.5) all have a separate Teredo entry.

Rémi Denis-Courmont

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