Subject: Re: How to use properly ipv6 autoconf over a router interface?
To: Brian Ginsbach <>
From: Steven M. Bellovin <>
List: tech-net
Date: 05/04/2006 17:44:58
On Thu, 4 May 2006 21:09:13 +0000, Brian Ginsbach <>

> On Thu, May 04, 2006 at 10:18:45PM +0200, Hubert Feyrer wrote:
> > On Thu, 4 May 2006, Steven M. Bellovin wrote:
> > >No, I don't like it, either, which is why I conclude that this isn't a
> > >fruitful path to pursue.  Your goal is very reasonable, but I don't think
> > >you can do it the way you've suggested.
> > 
> > I had an idea on the whole "setup my wlan laptop as router" scenario:
> > 
> > Initially, you have no address at all.
> > Then, you ask for one ip address (via DHCP, autoconfiguration, whatever)
> > That's the standard 'laptop' case so far.
> > 
> > When you want your 'laptop' to become a router all of a sudden, you 
> > basically need more address space. I wonder why not just ask for it, as 
> > you do in the first case (DHCP, ...), and then advertize it on the 
> > "internal" network/interface, and just route it.
> > 
> > I'm not sure DHCP or anything on this planet is prepared for the second 
> > inquiry, but it would prevent the need for ad-hoc addresses and 
> > NAT.
> > 
> Seems like RSIP (RFC 3102-3105) could work well here.
RSIP is a form of NAT.  It's cleaner and better than traditional NAT, but
it is NAT-like.  Also note that the protocols are experimental, not
standards track.  I don't think anyone has tried to use them with v6.

		--Steven M. Bellovin,