According to this Reddit thread, GTA Online uses a P2P (Peer-to-Peer) network instead of actual servers on their end. This is obviously very cheap and allows for hacking, which is fairly common especially on the PC version. A solution are invite-only sessions or friend-only sessions, but they have the disadvantage that you cannot do the CEO missions from the "Further Adventures in Finance and Felony" DLC.
Is there a way I can whitelist certain IPs in this P2P-network, so that I can create a "Public" Freeroam Lobby with only my friends? Any pointers to special software or exploitable network internals would be appreciated.