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Right now we own one domain name (e.g.

From the internet i can connect to a variety of networked devices using that single DNS name:

                         ╔════════════╗              ╔══════════════╗
                         ║device with ║  ┌─────────80╢Web Server 1  ║
                         ║ public IP  ║  │┌────────81╢  ║╫────────────╫──┘│┌─────3389╢              ║╫────────────╫───┘│         ╚══════════════╝╫────────────╫────┘         ╔══════════════╗╫────────────╫────────────25╢E-mail server ║╫────────────╫───────────110╢  ║╫────────────╫──────────3389╢              ║╫────────────╫────┐         ╚══════════════╝╫────────────╫───┐│         ╔══════════════╗   ╫────────────╫──┐│└──────443╢Web Server 2  ║╫────────────╫─┐│└──────3389╢  ║ 
                         ╚════════════╝ ││           ╚══════════════╝
                                        ││           ╔══════════════╗   
                                        │└───────3389╢Desktop PC 1  ║ 
                                        │            ║ ║
                                        │            ╚══════════════╝
                                        │            ╔══════════════╗   
                                        └────────3389╢Desktop PC 2  ║ 
                                                     ║ ║

Now, with IPv6, i can give all these devices a publically routable IPv6 address:
      ╔════════════╗              ╔══════════════╗
      ║Gatway      ║              ╢Web Server 1  ║
      ║Firewall    ║              ╢2001::10      ║
      ║2001::1     ║              ╢              ║
      ║            ║              ╚══════════════╝
      ║            ║              ╔══════════════╗
      ║            ║              ╢E-mail server ║ 
      ║            ║              ╢2001::11      ║ 
      ╚════════════╝              ╢              ║ 
                                  ╢Web Server 2  ║ 
                                  ╢2001::12      ║ 
                                  ╢Desktop PC 1  ║ 
                                  ║2001::2:100   ║
                                  ╢Desktop PC 2  ║ 
                                  ║2001::2:101   ║

But i only own one domain name, which can only resolve to one IPv6 address:

  • 2001::1

So how to i find the IP address of all my other devices? The simple method is to use my firewall device as a proxy - which is the functionality that NAT provides. The undesirable, and expensive way, is to find a free domain name for every IPv6 address i own.

What's the IPv6 equivalent of NAT?


The other problem is that IPv6 does not allow

you have to use:

So if a user forgets the www, then your site will appear broken.

Same way that IPv6 does not allow:

as you have to use:

and it doesn't allow

> ventrillo

you have to be sure to tell users:

> ventrillo
share|improve this question
Re edit: Nonsense. IPv6 does allow this; many websites simply have an AAAA record on the bare domain, such as What IPv6 makes a little harder is having multiple computers behind a single name, but that's purely a limitation of Linux ip6tables, which lacks -j REDIRECT. However, it already has -j TPROXY which can be used in a very similar way. – grawity Mar 28 '12 at 5:50
@grawity i've asked the question of how to do it here:… – Ian Boyd Mar 28 '12 at 11:45
up vote 3 down vote accepted

That's what subdomains are for.

If you own, for example,, you can freely create,, (If you don't – buy one, they are fairly cheap. Or visit or for a free domain.)

Also, you do not need NAT in order to forward ports. Try ip6tables with -j TPROXY.

share|improve this answer
They may be cheap; but getting one i want would be pretty darn impossible. But i can't believe i forgot about subdomains. On the downside right now people can use for http, smtp, pop3, that all breaks with subdomains. – Ian Boyd Aug 4 '11 at 18:57
@Ian: There's so much more than .com and .org, if all you need is a cheap domain. (I do wish more software supported SRV for service discovery, reconfiguration is indeed a pain.) – grawity Aug 4 '11 at 19:20

What makes you think that you only own that domain name, and no subdomains thereof? Conventionally in the domain name system, the owner of thereby gets to be the owner of

  •, and even

If you don't have control of the subdomains, then you don't really own the domain in the first place. If you do own the domain, then the answer here is the simple and straightforward one that the rest of the world widely uses. ☺

share|improve this answer
What makes me think that i don't own subdomains? Cause i forgot! And also cause i don't really own the domain in the first place ( - and they don't let me have subdomains (for free). But i'm going to give the accept to grawity; he beat you to it. – Ian Boyd Aug 4 '11 at 18:55
If SuperUser — as, alas, it didn't — had told me that grawity had answered whilst I was writing my answer, I'd have just upvoted instead, on the that-would-have-been-my-answer-too principle. ☺ – JdeBP Aug 5 '11 at 13:14

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