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Deploy360 1 January 2019

NAT64Check Version 2 is launched!

By Kevin MeynellFormer Senior Manager, Technical and Operational Engagement

With the New Year comes the launch of NAT64Check version 2 from the Internet Society. The first version of NAT64Check was introduced a couple of years ago and has proved very popular and successful, so for the past year we’ve been working on a number of enhancements in response to feedback and requests. And we’re very happy to be able to make the new version available as we welcome in 2019.

NAT64Check is a tool developed by the Internet Society in collaboration with Stichting IPv6 NederlandGo6, SJM Steffann, Internetbureau Max and Simply Understand. This allows you to enter the URL of a particular website, and then run tests over IPv4, IPv6 and NAT64 in order to check whether the website is actually reachable in each case, whether identical web pages are returned, and whether all the resources such as images, stylesheets and scripts load correctly. It also compares responsiveness using the different protocols, therefore  allowing network and system administrators to easily identify anything is ‘broken’, to pinpoint where any non-IPv6 compatible elements need to be fixed.

The original version of NAT64Check though, ran on two separate servers at Go6 and the IPv6 Lab which each had a limited view of the Internet from a topological perspective, and did not allow results to be easily aggregated. This was because it was put together quickly as a proof-of-concept using scripting tools, but its popularity encouraged us to develop something that was more scalable and adaptable for the future.

Version 2 therefore introduces a distributed concept that allows for different test locations, and indeed allows people to easily install their own test instances. However, results can be aggregated from any or all of these test locations and queried via a central web interface. Other improvements include better error detection and feedback when problems are experienced with particular sites, and as well as extendability for additional tests.

The new modular based design is based around three core elements. Marvin is a module based on Chromium that can run as separate instances on servers in different geographical locations for testing services over IPv4, IPv6 and NAT64. Trillian is a module that can collect, compare and output these test results based on different user profiles, whilst the Zaphod module undertakes the aggregation and provides the centralised web interface. Students of “The Hitchhiker’s Guide to the Galaxy” will of course recognise from where the codenames were derived!

The tool is very easy to use – simply go to, type the URL you wish to check into the box at the top of the page, and the result should be returned within a few seconds. It’s simple and easy, and will help you identify what needs to be done to make your website accessible with IPv6.

We’re also calling out for volunteers to help improve the usefulness of this tool by installing their own test instances. This requires a KVM, a VM running Ubuntu 18.04, a login, sudoers file, separate IPv4 and IPv6 addresses and a static /64 routed to the VM.

Deploy360 also wants to help you deploy IPv6, so please take a look at our Start Here page to learn more.


NAT64Check was developed by our colleague Jan Žorž, Sander Steffann, Corinne Pritchard, Max Dammers, and Musa Stephen Honlue.

Disclaimer: Viewpoints expressed in this post are those of the author and may or may not reflect official Internet Society positions.

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