Re: [v4v6interim] [46translation] [BEHAVE] Proposal for new BEHAVE charter

[Iljitsch van Beijnum <[e-mail]>]

On 20 okt 2008, at 12:58, Rémi Denis-Courmont wrote:

> Did I miss anything?

The reason I brought up NAT66 in shim6 is that the right version of it  
could be implemented as a simple router rewrite not unlike what's been  
proposed in GSE/8+8 etc which would be very useful for shim6.

Stable internal addressing when external connectivity changes could  
also be useful.

> I still believe we will see NAT66. Not because it's immediately  
> useful. Rather
> because someone will figure out it's easy to adapt NAT44 code to do  
> NAT66.
> For instance, much of the Linux Netfilter framework has become IP
> version-independent lately, with NAT being the only one big remaining
> IPv4-specific chunk.

As I said, I already played around with such an implementation years  
ago. Of course it broke FTP, while FTP through NAT44 works because it  
normally uses passive and even if it doesn't the NAT that I used  
implements an FTP ALG.

> I guess only time would tell whether a NAT66 1:1 spec would help  
> prevent such
> the transport-dependent NAT66 being _deployed_. It cannot hurt to  
> write that
> spec, I suppose. In any case, the abomination will be  
> _implemented_ :-( It is
> too natural/easy/tempting.

The IETF could exhibit some leadership by saying it will accommodate  
the pure address rewriting that would be caused by NAT66 by making  
applications that use referrals work through that, but not accommodate  
port overloading. That might be enough to keep a port overloading IPv6  
NAT from becoming widespread. (Or not. But it might.)

Of course the IETF could also come out and say that it will not  
accommodate any type of IPv6 NAT.
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