[Kea-users] Problems trying to implement RFC 8925 (v6-only-preferred)

[Dan Oachs]

Ah, ok.  In my experience, devices that don't support DHCP option 108, are
not ready to live on an ipv6 only network, and need some sort of ipv4 to
function.

--Dan


On Mon, Jul 31, 2023 at 1:42 PM Brian Candler <b.candler at pobox.com> wrote:

> On 31/07/2023 19:32, Dan Oachs wrote:
> > I'm confused.  What is the issue with Kea offering v6 only clients an
> > ipv4 address?  The client will not accept the ipv4 address and kea
> > will not reserve that IP address for them.  The end result is a
> > drastic reduction in ipv4 pool usage.  At least, that's how it is
> > working for me.
>
> This is a proof-of-concept IPv6-only network: no IPv4 addresses at all,
> and no NAT44 (only NAT64).
>
> You are correct that RFC8925-aware clients refuse the IPv4 address
> offered. However if someone plugs in a non-RFC8925 client, and Kea
> offers them an IPv4 address, they will use it.
>
> That's why I want to detect whether the client is announcing RFC8925
> capability, and I was hoping for something less ugly (and more robust)
> than this:
>
>      "client-classes": [
>          {
>              "name": "rfc8925",
>              "test": "substring(option[55].hex, 0, 1) == 0x6c or
> substring(option[55].hex, 1, 1) == 0x6c or substring(option[55].hex, 2,
> 1) == 0x6c or substring(option[55].hex, 3, 1) == 0x6c or
> substring(option[55].hex, 4, 1) == 0x6c or substring(option[55].hex, 5,
> 1) == 0x6c or substring(option[55].hex, 6, 1) == 0x6c or
> substring(option[55].hex, 7, 1) == 0x6c or substring(option[55].hex, 8,
> 1) == 0x6c or substring(option[55].hex, 9, 1) == 0x6c or
> substring(option[55].hex, 10, 1) == 0x6c or substring(option[55].hex,
> 11, 1) == 0x6c or substring(option[55].hex, 12, 1) == 0x6c"
>          },
>      ],
>
>
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