[Kea-users] help with dual stack ddns updates (replacing isc-dhcp with kea-dhcp)

[Bruno Meirelles]

Hi John, thanks a lot for the reply.

I read the documentation and found only this:
https://kea.readthedocs.io/en/kea-2.2.0/arm/ddns.html?highlight=ddns#dual-stack-environments
https://kea.readthedocs.io/en/kea-2.2.0/arm/dhcp4-srv.html#using-client-identifier-and-hardware-address

I changed 'match-client-id' to 'false' in dhcp4 and 0000 appeared in the 
DHCID. I tried to change in dhcp6 to stay the same, but dhcp6 does not 
accept.

Is there another way to change this in dhcp4?


Em 17/06/2023 09:47, John Dickinson escreveu:
> On 16/06/2023 20:23, Bruno Meirelles wrote:
>
>> 2023-06-16T15:44:55.089478-03:00 router kea-dhcp-ddns[6126]: DHCID: 
>> [00010161C842CCC250527045EDED24629529B402586F7336E34BF765A1C5D6ECB0B3B5]
>
>> 2023-06-16T15:54:35.615622-03:00 router kea-dhcp-ddns[6126]: DHCID: 
>> [000201A4DA3B65FDE300BAE9AD9B667E64199C8F12AA223B3AF1F569C46E640B7BD21F]
>
> It looks like you have different DHCIDs for v4 and v6. They need to 
> match so that ddns can see they belong together. See RFC4701 and RFC4361.
>
> The 0001 at the start means that the DHCID is generated from the 
> DHCPv4 client's Client Identifier option.
>
> The 0002 means that the DHCID is generated from the DHCPv6 DUID.
>
> You can sometimes tell v4 to return a DUID that matches the v6 one but 
> how depends on the dhcp client in use. Which is different depending on 
> the client OS in use and even what sort of install it is (Ubuntu 
> desktop is different from Ubuntu server)!
>
> I tried this a while ago and eventually gave up. I now use static 
> addresses pushed in to DNS by ansible. SLAAC to configure v6 addresses 
> and ansible scans the zonefile to find free IPv4 addresses. However I 
> don't have more than 3 or 4 "dynamic" clients where I care what IP 
> address they have.
>
> HTH
> John