[menog] IPv4 March 2011 depletion

Brian Candler B.Candler at pobox.com
Wed Nov 17 19:14:48 GMT 2010

On Wed, Nov 17, 2010 at 09:03:22AM -0800, Owen DeLong wrote:
> Since there is no universal need for ISPs to provide LSN and a higher
> level of service can be provided by placing all new customers on IPv6
> with NAT64, I think that the competitive landscape in most markets
> will limit the number of customers that accept LSN. Further, the idea
> of paying extra for a "real IP" only works if there is a real IP available
> for the carrier to provide.

Well, if using LNS the carriers can squeeze their bulk access customers by
anything close to 40:1, they could last a very long time on their existing

The difficulty will be for new carriers, and for those which host mainly
content providers.

When is the first major content provider going to accept being V6-only?  If
they pay $1m+ for a domain name, won't they be prepared to pay plenty to
remain visible on The (legacy if you like) Internet?

> > (*) OK, I'm a techie, and from my laptop I could probably use a tunnel
> > broker to get home if I could be bothered.  I couldn't use it from someone
> > else's PC where I have an ssh client but nothing else.
> Sure you can... If you have a meet-me dual-stack SSH server in
> between, anything that would work from that environment to your
> IPv4 based home will work to your IPv6 based home.
> For example, if you have an IPv6 web server at 2001:db8::3eb
> and an SSH server that is at and 2620:db8::558
> and you are on a box at which gets natted
> to, you can execute the following:
> ssh -L 8000:2001:db8:3eb:80 mylogin at

That's neat, I hadn't thought that a V4-only ssh client may still parse a V6
address or treat it as opaque.  I needed a slightly different syntax to make
that work:

$ ssh -L '8000:[2001:db8::3eb]:80' mylogin at x.x.x.x

But even if that didn't work, using a hostname should be fine, because
(IIRC) it's the far end of the tunnel which does the name resolution:

$ ssh -L 8000:v6.example.com:80 zino

Of course, you're assuming an account on a server with a public IP. With V4
behind NAT you can do it the other way round, by opening a connection from
your home server and leaving it open:

$ ssh -o GatewayPorts=yes -R mylogin at 

Your way is certainly more robust and flexible.

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