And what about server lock? I've played with a guy that told me he can remove my server from the master-server list and add it back there, or somehow lock it, so other players couldn't join it anymore. And i do believe he was not bluffing, because when we started playing, the server filled up in a few minutes, but later it was only 3 of us (he killed most of the people with RPG-7, and they disconnected). And then we played for almost an hour, and no one else joined. But then he told me he unlocked the server, and people started joining us again.
I also sometimes see unpassworded servers with like 5 or 7 players on them, but i can't join them, while the number of players on them can sometimes increase over time a little.
Also i once played on a server, where i got kicked as soon as the admin saw me, but the game was still going (because the timer and other statistics were only increasing when i joined back) or he restarted the server, but started not at 0:00 on the timer and daytime (or quickly switched the server to) but like 8:30 or bigger time and often it was night in the game (while i'm pretty sure the server had started just a few seconds ago). How to do all that stuff?