Microsoft and Teredo

Stephen Sprunk stephen at
Thu May 31 13:58:25 UTC 2007

Thus spake "Adrian Chadd" <adrian at>
> On Thu, May 31, 2007, JORDI PALET MARTINEZ wrote:
>> In windows, you have IPv6 firewall, so even if Teredo traverses
>> the "IPv4 security", there is still something there.
>> A good description of all this is available at:
> I've read that; but again enterprise and ISPs may impose restrictions
> on the types of traffic to/from end users, and this circumvents that.
> Host-based firewalls are not the be all or end all of network security.

The simplistic answer is that a site with IPv4-only security devices has to 
choose whether they're going to allow or block all Teredo/6to4 traffic.  If 
they want finer control, they need to upgrade to a native v6 network and 
native v6 security devices.


Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov 

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