My mod changes vanilla movement under water so you don't sink automatically and you swim in the looking direction. But since movement is always handeled client side I noticed that my mod can easily be used to cheat on a PVP server, because the mod has only to be installed on client. Can I change something so that it can't be used as a cheat engine? Also it seems very, very simple to create a speed enhancing mod which only makes the player 1-2% faster. That would be hard to track from a server be still gives you an advantage.

Edited July 15, 20196 yr by Meldexun

Yes it is a common problem in client-server games. Ideally all "game truth" is enforced by the server but in order to get smooth movement and minimize network traffic the client usually processes the immediate movement with the server just sampling it to check the validity. But the problem then is how much "tolerance" the server has in this verification. The server can and does rule out impossible movement but what about the fringes of what is possible?

 

As an ethical mod maker you can add a barrier to using it for cheating yourself by making your mod require that it also be loaded on the server. Of course a hacker type person could still figure out a work around I'm sure, but at least you know that you have done as much as the vanilla game itself does to protect against it.

I was also thinking of adding a check if my mod is loaded on the server too. But a hacker could more easily write his own mod than hack into mine.

Yes, it's one of the common issues with modern gaming, along with the server sending the client data extending beyond that which the player is supposed to have access to.

 

If your case I wouldn't worry about anything beyond some basic server-client mod matching checks as you said.

 

If you wanted to go all-out you would have to completely rewrite MC's control model, which I don't suggest (mostly due to how much work would be involved, plus all kinds of possible compatibility issues)