IPv6 is an important topic, and Steve Gibson pretty much botches it in his Security Now! episode 25.

I don’t want to criticise what Gibson is trying to do on this podcast. The area of security issues on the Internet is huge, and the breadth of reading he must undertake to understand the issues must not be underestimated. He is bound to make mistakes.

But on IPv6 Gibson’s is frankly wrong. He says:

If it weren’t for NAT router technology that basically allows many machines to share a single public IP, we really would be in trouble already with IP space depletion. But NAT routers happened, and they’re just a good thing for everybody. Corporations are using them. There are even some ISPs that are using NAT routers and putting all their customers behind a big NAT router because it really works very well, not perfectly, but very well, as most home users know. And so the prevalence and birth of NAT routing technology has hugely reduced the pressure on the move to IPv6.

Steve Gibson is wrong as follows:

  • NAT is not a good security solution. The part of NAT that is adding security is the same part that adds security in a non NAT perimeter firewall.
  • The gains from NAT have largely been achieved with respect to address depletion. NAT extended IPv4 to give us time to migrate to IPv6, but the gains are not limitless. See the posts on this blog about IPv4 address depletion – we have only about four years of IPv4 addresses left by current best estimates.
  • NAT actually doesn’t work that well. We are just getting good at working around its limitations. This is why Gibson endlessly pushes the proprietry non-standard Hamachi solution for encrypted tunnels, and other mechanisms to make some kind of peer to peer work on the Internet.

IPv6 has so much more to offer than Steve Gibson realises. Zero configuration, IP mobility, multiple addresses per interface, router discovery, link level encryption (he mentioned that one in passing), authentication… the list goes on.

He also says:

The problem is that it’s not easily compatible with IPv4. The problem that IPv6 is having is, you know, the manufacturers who are making the routers, I mean even, for example, the PC manufacturers are supporting Version 6, though no one’s using it yet. You know, Windows Server 2003 and XP can do IPv6. But you can’t get it anywhere. I mean, there’s nowhere to plug it in to get Version 6

Actually IPv6 does play very nicely with IPv4, and you can get it now. See for instance the BT Exact tunnel broker service. Some ISPs are now starting to offer IPv6 to their customers.

The real worry here is that Gibson clearly does not understand the mechanism by which we must transition from IPv4 to IPv6. There is not going to be a single big switch over. We must create islands of IPv6 (falling back on IPv4 automatically when we must). We connect these islands by one of the many tunnelling protocols, and as the islands grow, the sea of IPv4 is slowly pushed back. Before you know it we are all using IPv6 – just in time to stave off address depletion.

There is some good stuff in the Security Now podcast, but Steve Gibson saying IPv6 will never happen is not an example of it.