Dual stack DDNS

name: Dual stack DDNS
about: Documentation and feature request regarding Dual stack DDNS

Testing with kea 1.9.8 and Ubuntu 20.04 as dhcp client.

I find the documentation regarding ddns in dual stacked networks a bit confusing. 8.2.21. Using Client Identifier and Hardware Address https://downloads.isc.org/isc/kea/1.9.8/doc/html/arm/dhcp4-srv.html#using-client-identifier-and-hardware-address talks about the need for matching identifiers and gives the distinct impression that it works in Kea. However, 13.1.3. Dual-Stack Environments https://downloads.isc.org/isc/kea/1.9.8/doc/html/arm/ddns.html#dual-stack-environments clearly says that Kea does not currently support this feature.

Please could you add a Note to the 8.2.21 section saying that this is not supported or better yet could you add this functionality. If you just do the doc update them you also need to fix the text referring to RFC4703 to be RFC4361 in section 13.1.3 (the link is of it's just the text that is wrong).

As for adding this feature, I have seen a couple of messages on kea-users related to this that have no response.

From what I can see with wireshark all the information needed to do this is provided in a v4 client identifier and is identical to that in v6. Here is a hexdump of the Client Identifier option in both v4 and v6:

v4
0000   3d 13 ff 5d e2 6c 15 00 02 00 00 ab 11 9a 57 20   =..].l........W 
0010   95 71 61 bd d0                                    .qa..

v6
0000   00 01 00 0e 00 02 00 00 ab 11 9a 57 20 95 71 61   ...........W .qa
0010   bd d0                                             ..

As you can see both contain 00 02 00 00 ab 11 9a 57 20 95 71 61 bd d0 and in v4 the third octet is ff (255) as specified in RFC4361 6.1 If you are going to add this feature please could you give some idea of timescale? If this is not a priority, let me know I could try and find some time to hack together a fix :)