Server validation to check packets

NinjaTeabag

I think having the server checking data packets sent in from clients will be the thing to kill off hacks.
Data packets are information being sent to a server they usually just contain information like position, health, ammo and etc.

Of course when you're buying a ZP/GP crate your client sends information to the server that you want to buy crates and the server checks your zp/gp balance before giving you the crates.
Without checking it, a cheater can just tell the server that they're opening 5000 crates that they don't even have.

In Runescape there is a hack where a player dropped a very expensive rare item. He copied the packet of the information that the rare item is being dropped.
He picked it back up and then he spam the same data packet over to the server many times causing it to duplicate on the ground.
Then he picked the duplicated items back up again and caused the price of the item to crash.

Now Runescape does packet validation.
If anyone were to spam the packets to create dropped items it first checks if the item exists in the player's inventory at least before creating the ground item instance of it.

How this can be applied to Crossfire:

Checking the position of the player to ensure that're not going under the map or flying.
Checking the animation of the player so that they're not doing the "dead" animation where they're lying on the ground and being invincible.
Checking the speed movements so that they're not speeding.
Checking the weapon speed so that they're not speed slashing, if a weapon's stab speed is 0.1 seconds per stab then it's obvious that the player is speed knifing.

"This will create lag on the server"
-.- No it will not. A few if-statements won't kill a server.

I'm out of time now.