Workshop: Getting web and mail servers ready for IPv6

The Journey Is the Objective

Article from ADMIN 05/2011

By Michael Prohm

If you run a web server and a mail server and anticipate that users from Asia are headed towards your dedicated server, it's time to get it ready for IPv6.

Migrating the company's local network to IPv6 will not make much sense in the next few years. The situation is different for leased dedicated servers, or ones that have a genuine IPv4 address and are thus part of the Internet. If you have customers from Asia who use native IPv6 to surf the Internet, it definitely makes sense to prepare the services that you provide on IPv4 for IPv6. It is primarily the 4,000,000,000 inhabitants of this continent who are affected by the scarcity of IPv4 addresses – and who are thus the earliest adopters of IPv6. This situation will mainly relate to your web offerings, possibly followed by your mail server.

In this article, I'll describe a useful strategy step-by-step – and there are many pitfalls to watch out for. The first step is to ask yourself how many addresses you need and how big your IPv6 network is going to be. If your mail server and web server only have IPv4 addresses, and you just want to make sure they have IPv6 addresses, you will be fine with just one address, or a /64 network.

To test whether your configuration actually works, you also will need a local machine that speaks IPv6. If your ISP doesn't support IPv6, you can resort to a tunnel broker such as SixXs.net [1]. Alternatively, you can build an IPv6-in-IPv4 tunnel to the server you want to configure, which is possible within an OpenVPN connection. To allow this to happen, you need to ask your provider to give you an IPv6 network of the right size, which you then segment into smaller /64 networks, before configuring one of them for the tunnel.

Preparing DNS

Before you start to configure your new IPv6 addresses on the server, you need to make a few preparations, including creating valid DNS reverse entries for the IPv6 addresses you will be using (Figure 1). Because

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