Support PREF64 for Router Advertisements

[samip5]

Important notices

Before you add a new report, we ask you kindly to acknowledge the following:

• [x] I have read the contributing guide lines at https://github.com/opnsense/core/blob/master/CONTRIBUTING.md
• [x] I am convinced that my issue is new after having checked both open and closed issues at https://github.com/opnsense/core/issues?q=is%3Aissue

Is your feature request related to a problem? Please describe.

This request is relevant to IPv6-only networking, as this is one of the prerequisites for deploying IPv6-mostly network.

Describe the solution you like

I would like to be able to specify PREF64 (RFC 8781) option for Router Advertisements.

Describe alternatives you considered

N/A

Additional context

Relevant is RFC 8781

[fichtner]

It's scheduled for radvd 2.20 but there is no final release for it yet, check

https://github.com/radvd-project/radvd/blob/master/CHANGES

[samip5]

Huh, I thought the version of radvd already had it, but maybe not then..

[fichtner]

Just check the link, it's a definitely not yet :)

[samip5]

I did check, thus my reaction. :)

[fichtner]

I thought they were ready to release not sure what happened. I'll keep an eye on it.