As I explained before, you can not get hacked from in-game. I also explained how the client works. In this part I will explain how you can not get hacked from in the game, it’s impossible.
People think that you can get hacked if whispered to or traded. To explain this, I looked at a few packets (legit). When the client sends the whisper packet, it sends the header, same as in all data packets. After that it will send the recipient and the message that you are sending that person. Based on the recipient, the server will most likely then send a data packet to the receiver. Nowhere in this relationship to the two clients communicate at all in any direct way; the server does all that for them, as it should. In no way can a hacker abuse whispers.
Trades are similar. The client will send a packet for spawning a trade, the server will then most likely make a new object for that trade. An object is basically a data space reserved for a set of data containing properties and such. After that multiple packets are sent between the two clients and the server, but the two clients never directly interact in any way. A hacker can not abuse this relationship in any way either.
Surly you must think that the clients have a link when you are in the same map. Sadly, that is not true. There are packets for spawning the player, moving the player and just about everything you can think of. When coded properly, this does not lag at all. Look at google; it searches over 8000000000 pages every search in less than 1 second.