IPv6 <-> NAT <-> IPv4 ... possible?

[Max Laier]

On Friday 19 October 2007, Marc G. Fournier wrote:
> Could I hide an IPv6 network behind NAT?  I don't know if that is even
> possible ... the IPv6 IPs would be private (equiv to 192.168.x.x) ...
> basically, none of the hosts behind NAT need a public IP, *but* I may
> end up with more then 256 hosts, so was wondering if using IPv6 behind
> the NAT would be 'simplier' ...
>
> If possible, pointers to docs to read would be appreciated ...

Possible - yes.  Practical - no.  There are a couple of techniques 
available that can provide the functionality you are looking for.  All of 
them solve a subsection of the problem, but there is no - to my 
knowledge - complete sollution.

The three main technologies are:
1) TRT (implemented through faith(4) / faithd(8))
2) Header translation (I don't know if we have this implemented anywhere)
3) (Transparent) application proxies
     - there are patches for squid - IIRC

For 1 and 3 you have to run a AAAA to A translating DNS server.  2 is the 
most "transparent" one, but I don't know if there is an implementation 
available.

All in all, it's a PITA.  Much, much worse than NAT.  For the moment - if 
you want your clients to do more than just surf webpages - you want NAT.  
If it's only about surfing WWW you could try a (transparent) web proxy on 
your dual stack router, but don't expect to find a lot of documentation!

-- 
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