The server gets the IP address from the accept4() system call. It ignores HTTP headers (e.g. x-forwarded-for) when determining the IP.
It's possible to claim IPs by embedding <img src="//ipv4.games/claim?name=jart"> on a web page. My web server will notice the Accept header wants an image and will serve a 1x1 transparent gif rather than an html response. That's how I play the game: https://justine.lol/ The whales normally don't do this. They usually have something like a Go or Python script which sends bare minimal HTTP requests. On Sat, Aug 16, 2025 at 2:21 AM Saku Ytti <[email protected]> wrote: > Couldn't they just ensure that some popular pages that people visit > have a link to the claim? > > You're not telling much how the ipv4.games works or what the requests > are like which makes it quite hard to speculate. > > > In the headers, do you see various user agents being used, and various > formatting and permutations of options? > > > On Sat, 16 Aug 2025 at 09:15, Justine Tunney via NANOG > <[email protected]> wrote: > > > > I operate an online service at https://ipv4.games/ that invites people > to > > send http requests to my web server from a lot of different IP addresses. > > In order to claim an IP, you need to successfully make a tcp three-way > > handshake with a VM on Google's network. > > > > Somehow a player in Europe named femboy.cat has successfully managed to > > claim 20 million IPs, which is 9% of all IPv4 hosts according to Censys. > > > > Does anyone have any idea how they're doing it? > > > > Would anyone here be willing to be their North American rival? > > _______________________________________________ > > NANOG mailing list > > > https://lists.nanog.org/archives/list/[email protected]/message/MMCCEQKA4UPGGWFWEBWLYKHTYCAOQIZS/ > > > > -- > ++ytti > _______________________________________________ NANOG mailing list https://lists.nanog.org/archives/list/[email protected]/message/PN6RSJUQ2QM6ZHGAZWSVCCEOFTK3UW7N/
