FreeBSD and IPv6 Tunnel

Sun 19 December 2021

Huricane Electric is one of IPv6 tunnel providers and this post is specifically about setting up FreeBSD router with a tunnel and the configuration for IPv6 autoconfig caller Router Advertisment (RS, on the router) and Router Solisticion (RS, on desktop or laptop). If you know how DHCP for IPv4 works, you will find it a bit weird how IPv6 works. First, in IPv6 world what is called DHCPv6 is closer to what DHCPv4 does than RA/RS. Here, RA/RS setup will be described. The end result is that router and clients have access to IPv4 and IPv6 at the same time, or in how it's called "Dual Stack".

Router

Although Huricane Electric will give you exact commands/config for operating system of your choice, I'm showing here whole configuration for completeness. The address range fd12:c09a:85be:4851:: is just a dummy one, you should use the one HE provides.

In /etc/rc.conf:

ifconfig_re1="up"
ifconfig_re2="up"
ifconfig_bridge1_name="lan"
ifconfig_lan="addm re1 addm re2 addm wlan0 stp re1 stp re2 stp wlan0"
ifconfig_lan_alias0="inet 192.168.0.1 netmask 255.255.255.0"
ifconfig_lan_ipv6="inet6 fd12:c09a:85be:4851::3 auto_linklocal -ifdisabled"

# HE IPv6 tunnel
gif_interfaces="gif0"
gifconfig_gif0="<MyIPv4> <HEIPv4>"
ifconfig_gif0_ipv6="inet6 fd12:c09a:85be:4851::2 fd12:c09a:85be:4851::1 prefixlen 128"
ipv6_defaultrouter="fd12:c09a:85be:4851::1"

In /etc/rtadvd.conf:

lan:\
  :addrs#1\
  :addr="fd12:c09a:85be:4851::"\
  :prefixlen#64\
  :tc=ether\
  :rltime#0\
  :rdnss="fd12:c09a:85be:4851::3"\
  :dnssl="meka.rs"

In /etc/rc.conf.d/rtadvd:

rtadvd_enable="YES"
rtadvd_interfaces="lan"

Desktop/Laptop

In /etc/rc.conf:

cloned_interfaces="lagg0"
wlans_iwn0="wlan0"
ifconfig_wlan0="ether f0:de:f1:64:2c:3b WPA up"
ifconfig_em0="up"
create_args_wlan0="country US regdomain FCC"
ifconfig_lagg0="laggproto failover laggport em0 laggport wlan0 DHCP"
ifconfig_lagg0_ipv6="inet6 accept_rtadv -ifdisabled"
ipv6_defaultrouter="fd12:c09a:85be:4851::3"
rtsold_enable="YES"

Configuration is based on Router and Laptop on FreeBSD. It can be simplified if you use only wlan, which probably means you don't need bridge at all hence you should configure wlan0, for example.