Update only IPv6 prefix

[favonia]

Inspirations:

• IPv6 - Fixed Suffix, Dynamic Prefix timothymiller/cloudflare-ddns#191
• https://www.reddit.com/r/networking/comments/121cr6p/ipv6_dynamic_dns
• https://www.reddit.com/r/PFSENSE/comments/emmz7l/dynamic_dns_with_address_substitution_using_ipv6/

Difficulties: how to decide suffixes when creating new DNS records?

[favonia]

• Environment variable: IP6_PREFIX_LEN
• Default value: 128
• Effects:
  • When updating records, only the prefix was compared and changed. (To have the correct results, records must be re-fetched when IP6_PREFIX_LEN < 128.)
  • When creating records, use the current IP (because there's currently no way to specify host IDs)
  • When adding the detected IPv6 range to a WAF list, use the prefix length max(12, min(64, IP6_PREFIX_LEN))
• Remaining issues: how to specify host IDs for domains?

[Viermusketiere]

A suggestion on this issue:
It would be a nice feature if one were able to specify the MAC address of a host which then gets translated into a IPv6 address based on the prefix and the suffix generated from the MAC address. DynV6 is using this and I find it a very pleasant and easy to use feature.

[favonia]

@Viermusketiere Thanks! That's a very interesting idea. I tried to find the technical details on https://dynv6.com/docs/apis but could not find them. Could you possibly help me locate the documentation of the feature?

[Viermusketiere]

The dynv6 documentation is quite compact but you could find a simple reference here:
https://dynv6.com/ or here https://community.dynv6.com/t/how-to-use-the-ipv6-prefix-mac-address-lookup/238.
This is a reference from my account:

The system is based on SLAAC and requires this option to be enabled on the client. Per standard every IPv6 client should support SLAAC.

[favonia]

• Remaining issues: how to specify host IDs for domains?

After some struggling, I'm leaning towards this notation for IPv6 host IDs: example.org[::11:ab05].

MAC addresses can be supported as example.org[aa:bb:cc:dd:ee:ff], though not a priority.

[favonia]

@Viermusketiere Hi, I have a design question: If you input an EUI-64 (not EUI-48) directly, would dynv6 recognize it as an IPv6 address or an EUI-64 address? For example, if you put in

02:00:5e:10:00:00:00:01

what will dynv6 do?

[favonia]

@Viermusketiere Never mind. I guess by saying "MAC", it only supports EUI-48, and thus all cases can be parsed unambiguously.