IPv4 -> IPv6 "bridge" ?

Andrew Yourtchenko ayourtch at gmail.com
Tue Oct 12 11:20:02 CEST 2010

On Tue, Oct 12, 2010 at 11:03 AM, Xavier Beaudouin <kiwi at oav.net> wrote:
> Hello,
> The thread about IPv6 Future, how will you solve IPv4 connectivity, is for me also a problem.
> I operate a new born cloud computing company in France (we do only this kind of business, exclusively), and we have the problem of IPv4 exhaustion...
> We had an idea to do IPv6 only on all hosts and create a kinda bridge with our /21 (at starting) to do IPv4 -> "internal" IPv6 host that must be reachable from IPv4 "old internet", also this mapping has to be done in direction IPv6 host -> IPv4 when this host needs to reach some IPv4 stuff.
> Unfortunatly it seems to be not easy, even in the free world (for example OpenBSD...)...
> Anybody has some pointers, rfc or what else to implement that ?

Admittedly a weekend hack, but maybe of some use to you - if you are
fine with HTTP-only nature of it:


The basic idea is to terminate the session, read enough of the data to
find the "Host: " header, then do the resolution of Host and establish
the second leg of the connection that way. Obviously you will need
some kind of split-DNS for that, which needs to be thought about some

I've done this for one proof of concept for v6->v4 connectivity, but
indeed nothing prevents to do it in the other direction. Maybe you can
play with this idea and see if that is something usable for you.

***WARNING***: Again, it's a quick proof of concept hack that I made
on one of the weekends and did *not* extensively test, so expect bugs!
And do not use this code as-is in production - it eats newborn babies
and causes the unexpected tsunami  waves!


> Also we don't want dual stacks, VPN and some fscking from people that using too mutch RFC1918 networks will gave some ipv4 collisons... That's why we want to force end users to use IPv6 exclusively (since there is as least 2 ISP that provide native or near native IPv6 connectivity in France), this can be "the ipv6 killer application" to force the world to move really to IPv6....
> Regards,
> Xavier

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