FreeBSD IPv6 Tunnel Config
In /etc/rc.conf:
ipv6_enable="YES" ipv6_gateway_enable="YES" ipv6_defaultrouter="-interface gif0" ipv6_default_interface="gif0" gif_interfaces="gif0" gifconfig_gif0="A.B.C.D 81.187.81.6" # substitute the IPv4 address of your machine for A.B.C.D ipv6_ifconfig_gif0="2001:08b0:XXXX:1::1 prefixlen 64" # 2001:08b0:XXXX should be replaced by your /48 allocation # in this case I have used IP 1 on subnet 1 as the IPv6 # address - you can (and probably should) adjust as desired.
Don't forget to configure an IPv6 firewall (this is left as an exercise for the reader).