Running 12.1 and working on adding ipv6 public network provided by my ISP. Been using ipfilter since fbsd 4.0. Reading /usr/share/examples/ipfilter I find there are no examples about ipv6. Further more there are no ipfilter ipv6 info at all in the handbook.
The README file gives 2 url's for the home of ipfilter which are now dead.
ipfilter documentation across the board needs to be updated to include ipv6 support.
My contact at NetBSD is good friends with Darren. Darren has stopped maintaining IP Filter for now.
I have used ipf in FreeBSD since FreeBSD 3 and Solaris since 2.3, before it was part of either O/S.
I and Christos at NetBSD maintain it, sharing patches and fixes. I have forked a copy onto github, though I've yet to merge my work here on FreeBSD back to it.
I have also been asked to merge ipf 5 into Illumos but have yet to find the time for it. They have added a zone feature that I need to implement in FreeBSD before updating their copy to 5.1.2.
IPv6 support in ipf is incomplete, it's missing from ippool in the kernel, my current focus. There are a number of inconsistencies between the kernel module and the userland that still need to be addressed.
IPv6 support was added late in the ipfilter 4 release cycle.
Unfortunately I am an unpaid volunteer. Support is as an unpaid volunteer as I have time. I must prioritize. I am willing to accept patches for the handbook and for /usr/share/examples/ipfilter to expedite this. Otherwise as an unpaid volunteer I must prioritize as my time permits.