IPv6 ingress filtering

[Enno Rey]

Hi,

On Fri, May 17, 2019 at 01:45:56PM -0700, Kurt Buff - GSEC, GCIH wrote:
> Forgive the intrusion, as I seek a bit of clarity.
> 
> MSFT DirectAccess seems to use the address range in question:
> 
> Tunnel adapter iphttpsinterface:
> 
>    Connection-specific DNS Suffix  . :
>    IPv6 Address. . . . . . . . . . . : 2002:4332:aaaa:bbbb:cccc:dddd:eeee:ffff
>    Temporary IPv6 Address. . . . . . : 2002:4332:aaaa:bbbb:cccc:dddd:eeee:ffff
>    Temporary IPv6 Address. . . . . . : 2002:4332:aaaa:bbbb:cccc:dddd:eeee:ffff
>    Link-local IPv6 Address . . . . . : fe80::75e4:c4b3:fae6:237c%2
>    Default Gateway . . . . . . . . . :
> 
> It seems to me that filtering this range might hurt a bit, unless I'm
> mistaking what some are proposing.

not being an MS DirectAccess expert I'd say that - given DA is a VPN technology, using IP-HTTPS as a (somewhat proprietary) tunnel tech - these addresses shouldn't be visible too much "in the [public] IPv6 Internet" so the proposed filtering (of this thread) shouldn't come into play.

cheers

Enno




> 
> Kurt
> 
> On Fri, May 17, 2019 at 1:06 PM Brian E Carpenter
> <brian.e.carpenter at gmail.com> wrote:
> >
> > On 18-May-19 06:12, Gert Doering wrote:
> > > Hi,
> > >
> > > On Fri, May 17, 2019 at 12:55:33PM -0500, David Farmer wrote:
> > >> A few questions;
> > >>
> > >> Are you generating ICMPv6 toward non-2002::/16 sources for traffic destined
> > >> to 2002::/16?
> > >> Are you generating ICMPv6 toward 2002::/16 source for traffic destined to
> > >> non-2002::/16?
> > >> For the later, where are you getting the route for 2002::/16 from?
> > >
> > > Indeed, as you said, filtering correctly (= ICMP unreachable, so clients
> > > can fail over quickly [if HE is not in use]) is hard.
> > >
> > > We still run our own relay, so do not filter today.  Mostly because I
> > > know it works and (since it's our relay) I can rely on it to not break
> > > things for people - and haven't had time to change that to "filter".
> >
> > And surely the question is "What would produce the most help desk calls?".
> > Filtering something that is presumably working for its remaining users
> > might not be a good idea from that point of view.
> >
> >     Brian

-- 
Enno Rey

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