Re: IPv4 Games

[Justine Tunney via NANOG <nanog () lists nanog org>]

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 <saku () ytti fi> 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
> <nanog () lists nanog org> 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/nanog () lists nanog org/message/MMCCEQKA4UPGGWFWEBWLYKHTYCAOQIZS/
>
>
>
> --
>   ++ytti
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