Server doubles

[stevomitric]

Depending on your Python implementation? Because of DoS amplification? I don't see any necessary reason that a fake server is forced to "go offline" (aka crash or not being able to send out fake server infos anymore)

Well, you can "crash" (or slow down) any server/PC with UDP flood. Sending 'getstatus' or 'getinfo' here just speeds up the process.

Spawning a fake server, collecting the IP of every user requesting a "getstatus" (aka a player refreshes all servers)

Every server has been put in a separate thread (works independently of others) and sends 'heartbeat' to masterserver (so it shows in a list). When you press refresh in CoD (or try querying the masterserver), you will get that list with the fake server. Then, your CoD will try to query every single server and when it gets to the fake one, fake one will send that same request to the original server being duplicated (works like a proxy).

sending then constantly for like a minute fake getstatus-responses with the spoofed IP's of all the other servers to the client who just reqested a getstatus from you

When client sends a 'getstatus' request, fake server just sends that request to the original server and forwards the response to the client. You can see how that flood is useful here. For every 13 bytes ('ÿÿÿÿgetstatus') client sends, 'fake server' has to send that 13 bytes to the original server + the response (at least 100 bytes) to the client.