IPv6 : Win7 vs Win8
Just an update: I eyeballed the “PrefixPolicies-Vista78.cmd” script from
that it was safe, and ran it. It apparently works, but I don’t have a
ULA setup to test it with.
jrey42 deserves kudos.
On 21/12/2015 07:57, Brian E Carpenter wrote:
On 21/12/2015 03:28, Marc Luethi wrote:
I suggest to investigate source address selection on the client side,
while closely following name resolution (assuming this is similar to
Windows 2012R2’s DA implementation, DNS64 is supposed to be at work, here)
and keeping an eye on the IPv6 routing table.
In your situation, I would presume that the end system ends up with an RFC
4193 address (from the /48 that was initially chosen when DA was set up) on
its *IP-over-HTTPS* tunneling interface (courtesy of the DA implementation)
and a global unicast address the (W)LAN interface, based on the CPE’s RAs.
While things *should* be neat, my experience with Windows 7’s way of
picking source addresses was so bad (“longest match” seemed entirely
unheard-of), I eventually gave up using RFC 4193 addresses for my internal
I repeateadely observed Win7 using its global unicast address(es) to access
internal ressources, while stubbornly sticking to te RFC4193 source address
when attempting to talk to addresses on the global IPv6 internet.
Yes. Apparently Win8 is up to date in that respect (i.e. follows RFC6724 not
RFC3484). It would be possible to make Win8 misbehave by changing the default
Conversely, it’s possible to make Win7 behave correctly by changing its default
policies to conform to RFC6724. I just found the following site that offers a
script (YMMV, I haven’t checked it):
But if that is the cause of the original issue, maybe switching off the
ULA prefix would be easier, and nicer than switching off IPv6.
On 19 December 2015 at 22:37, Kurt Buff wrote:
I ran into an interesting situation some months ago which still
baffles me, and though I was able to work around it, I expect it will
We implemented MSFT DirectAcess at our company quite some time ago
(using 2008R2 and Forefront 2010), and it works extremely well.
At least it worked well for everyone until one of the employees got
his Comcast connection upgraded, and then DirectAccess didn’t work for
that employee any more.
We proved that if he tethered to his cell phone, that would work, and
if he used an SSL VPN client while on his Comcast connect that would
work, but DirectAccess would not work at home.
Finally, I discovered that his Comcast-installed router was handing
our IPv6 addresses on his home LAN. Turning that off enabled
DirectAccess to work again.
We do not have an assigned IPv6 block from our ISP, though of course
MSFT OSes use it, and auto-assign themselves addresses, but for now
we’re ignoring it.
Has anyone run into this problem and solved it – not by turning off
iIPv6 address assignment for the home LAN, but really solved it? If
so, how did you do that?
Would getting and implementing an IPv6 assignment from our ISP cure
the problem, or make it worse?
I’ve found little guidance from MSFT about DirectAccess in an IPv6
environment, though I admit I haven’t been terribly diligent in my