Get your public IPv4 and IPv6 addresses

Live version: https://ip-test.ludovic-muller.fr/

The server part is just used to print the current IP used by the user, that's why in the server directory you will see a simple index.php file which print the IP address.

The client part is used to retrieve the requests to get the IPv4 and IPv6 addresses of the user. It's a basic user-friendly interface.

The hack will be there. How to get the IPv4 and the IPv6 addresses of the current user? The answer is very easy to understand: use DNS!

So we need three sub-domains, in my case:

• ip-test.ludovic-muller.fr: just point to the client part using CNAME or a combination of a A and AAAA records,
• ipv4-test.ludovic-muller.fr: only use a A record pointing to the server part,
• ipv6-test.ludovic-muller.fr: only use a AAAA record pointing to the server part.

The user loads the ip-test page. The page will make two requests using JavaScript to the two other subdomains: ipv4-test and ipv6-test. If a request fails, it would say that the IP version isn't supported by the client. In the other way, the request will directly give the good version of the user IP.