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Comment by vaylian | Hacker News Reader

But how do they achieve that? Do you use a lot of VPNs?

my first guess would be: server honors X-Forwarded-For where it should not?

Edit: looks like thats it: https://github.com/jart/cosmopolitan/blob/master/net/turfwar...

So basically someone is running a script iterates over the whole ipv4 range and calls the claim endpoint with each single adress in the X-Forwared-For http header once.

That only works if the proxy is sitting on localhost or a local network, just setting the header shouldn't work.

(I came here because I was curious how jart got 127 and 10, but after seeing the source is their's that's less of wonder..)

bool IsPrivateIp(uint32_t x) {

  return (x >> 24) == 10                   /* 10.0.0.0/8  */

         || (x & 0xfff00000) == 0xac100000 /* 172.16.0.0/12  */

         || (x & 0xffff0000) == 0xc0a80000 /* 192.168.0.0/16  */;

}

the code doesn't consider 127.0.0.0/8 as "private". I'm curious about 10.0.0.0/8 though.*

a simple proof of the opposite is that no one's yet to exploit any of the untaken ranges that way

The line just under that prevents public IPs from using that function.

you are right, I totally read that wrong. Confirmation bias strikes again!

Embedding images on a popular page?

But according to the servers status at http://35.223.193.241:443/statusz nearly all claim requests expected to get html back not images.

There's plenty of ways around that, for instance

    <script src="https://ipv4.games/claim?name=gruez">

    <iframe src="https://ipv4.games/claim?name=gruez">

I don't know, but check out the "Recent Successful Claims" on the right.

Edit: Apparently they run https://novo.tf/, a CAPTCHA service, so they're probably using that to call out to ipv4.games from their clients.

There are VPNs which use residential endpoints. You essentially use other users' IPs there.

They’re top of the list, so at least some is seeing that and choosing to add to it.

I wouldn't be surprised if they had it call out from guns.lol or something

Maybe spoofing source IPs.

can't spoof the source IP in TCP communication, as the handshake cannot happen.

With UDP you can send whatever, but obviously you won't be able to receive the response.

It used to be possible back in the days when sequence numbers were easily guessable. (You'd obviously not be able to receive, only send, so you couldn't do TLS, but TLS had hardly been invented at the time.) Now operating systems are way too good for that. :-)

Botnet maybe.

_nobody_ would waste a botnet of 9 million unique IPs like this.

Well let's not get hasty... These are valuable internet points we're talking about here.

Not if it's your own, but this would be a great opportunity to redirect a botnet hitting your severs to generate some internet points instead

it would be pretty funi though

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