IPv6in4 tunnel with only one /64 prefix

Frédéric Perrin frederic.perrin at resel.fr
Sun Dec 16 19:47:32 UTC 2012

Following-up on myself...

Of course Steve's suggestion was not what I wanted to hear, as I wanted
to do stuff myself :)

The take-away is that my plan works. I have a full write up in French at
<http://tar-jx.bz/notes/tunnels-ipv6.html> ; I can translate into
English if people are interested. Basically, you need to tell the
external interface that it is not in a /64 addres, then you can add the
routes you need. There is nothing special to do on the router at the
other end of the tunnel, except turning on the DHCPv6 server.

I did have to setup an NDP proxy, the (quite trivial) code is at

I did hit a bug in ISC dhclient. There is a fix in the Debian bug
tracker <http://bugs.debian.org/684009> (a similar fix in Network
Manager for desktop systems already made itinto their git).

Le mercredi 7 à 22:21, Frédéric Perrin a écrit :
> Hello list,
> I have a FreeBSD server with native IPv6 connectivity. At home, my ISP
> provides me with only IPv4 connectivity. In order to get IPv6 to the
> home, I had the idea of creating a 6in4 tunnel between my home gateway
> and my FreeBSD server. The part about creating the tunnel, routing
> between the home and the server works using private addresses (fc00::/8
> over gif0).
> However, I only have one global /64 on the FreeBSD box. What can I do?
> I have the idea of subnetting the /64 into e.g. /80, route a couple of
> /80s through gif to the home and use another /80 for the FreeBSD server.
> However, as the router into which my FreeBSD server is connected will
> expect the entire /64 to be directly connected, I will have to setup
> some kind of NDP proxy for the /80 to the home. I will also lose
> autoconf, but I can live with that.
> Comments, either on the plan above, or something else I haven't thought
> of?


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