How to configure IPV6 on FreeBSD 12

Bill Crowell, N4HPG n4hpg at
Sat Dec 29 16:54:45 UTC 2018

I found my system at various stages of updates within the 11 release series and tidied it up to v12 as it became an official release.

I use FreeBSD on a Zotac mini PC as a firewall, router, caching DNS server and for other things.

It has 2 nics - one public and the other on my LAN. It does NAT for IPv4 and I’m using the PF firewall with great results.

What I am NOT able to make work is IPV6. My ISP is Comcast and they support full IPv6 over DHCP and this worked on BSD 8 and 9 using the instructions here: <>

I need to get the IPv6 address from Comcast on device re1 with the first 64 bits and then provide the route for the LAN clients and the address space with bits 65+.

What is particularly MADDENING about the FreeBSD documentation pages is that they do not indicate which VERSION is being discussed. Therefore, I do not know which may apply to my version.


I have tried this method: <>

It does not work because dhclient -6 is broken


This appears to be a dead-end as well: <>


I have tried this, but it does not update my interfaces: <>


Using rtsol:



So, what should I be using?
dhcp6c - appears broken
dual-dhclient - appears broken
rtadvd - not well documented


FTR, I’ve been doing Unix of some sort or another since 1990. SCO, AIX, Linux, OS X, etc. FreeBSD was supposed to be my island of stability given the fork problem in Linux. That I’ve spent 20 hours with Google trying to find out how to set up an interface is maddening.

Bill Crowell
Pearland, TX
n4hpg at <mailto:n4hpg at>
There are 10 kinds of people: those who know binary and those who don't

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