Linux Modding client

Category: Only client BUT it used to cheat servers
Operating system: Linux Ubuntu Debian 12.04.2 LTS
Build number: 762
Description: You can change your movement on server using mods of client. I don't sure about other(i don't tried), but movement of player(position, velocity and etc) works.
Steps to reproduce:
1.Modify movement of player/change script of item to make it manipulate player.(for example, I made lantern add force to player, so gravity for him will be less, then for others, on left mouse button, so when i hold left mouse, I can't attacks/build , but i can jump higher).
2.You need to go to survial sandbox(image 1).
3.After this(image 2) moment you need to wait, and when map loads, you need to momentally press ESC.
4.It will look like this(image3).You need to quit and join server.
5.Images after this illustrate this bug, I was on BCB server, Wargod-Loki was there too. Also others see that i fly(when i press left click, lantern add force to me, so i fly up.Shield up needed for it.).
Screenshots/Videos: