Re: [IPv6] Can We Turn the Global Network into a Firewall Protecting All End Users?

On Wed, Apr 24, 2024, 07:46 Mark Andrews <marka@isc.org> wrote:

>
>
> > On 23 Apr 2024, at 16:51, Hubert W <hubert.wisniewski@gmail.com> wrote:
> >
> > Dear WG,
> >
> >
> > I woke up with one idea and I would like to challenge it.
> > In IPv6, every device receives a routable address. To protect endpoints
> effectively, we require firewalls to filter unwanted traffic.
>
> Apart from packet volume this is a false assertion.  No device should
> require a firewall.
>
> > But what if we could stop such traffic at the source? Could this
> approach convince more people toward adopting IPv6?
> >
> > According to RFC 7381: “In a /48 assignment, typical for a site, there
> are then still 65,535 /64 blocks.” and “All user access networks should be
> a /64.”
>
> /64 is typical not required.
>
> > Can we use then bit 63 to convey a message: “I don’t want any incoming
> traffic initiated towards me!!!”? Of course a response would be accepted.
> >
> > We could divide the /64 allocations into two groups: one for servers,
> and these accept incoming traffic (bit 63 = 0):
> >
> > for example 2001:0db8:0000:0000::/64
> >
> > And the second group: endpoints, these never accept incoming traffic
> (bit 63 = 1):
> >
> > for example 2001:0db8:0000:0001::/64
> >
> > We only need all systems to understand the message. If a router or
> firewall sees such a packet, then drops it.
> > Every TCP packet with flag SYN, where destination address (IPv6) has bit
> 63 equal 1, must be dropped.
>
> All the world is not TCP.  Additionally for TCP the filtering device would
> need to track state and that implies symmetric routing.
>
> > Would it be theoretically possible?
>
> No.
>
> > Best regards
> >
> > Hubert Wisniewski
> >
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>
> --
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742              INTERNET: marka@isc.org

I think there would be no issue with asymmetric traffic if we only check
SYN flag, but I understand that is not a good idea. Thank you for your
opinion.

Hubert Wisniewski