This plugin is a simple AntiCheat.
Today, Fly is banned on a variety of servers. Also, vanilla Minecraft servers provide the "allow-flight = false" feature. However, some clients bypass that detection, which annoys people. So I developed a plugin that can prevent that from happening. (I'm Japanese, so sorry my English is not good)

Updated frequently to improve false positives and detection rates.


Features
・Fix a vulnerability in Server's fly detection. (Fly)
・Fix a vulnerability that can put player in a fake OnGround state.(NoFall)


This will detect the following two modules.
・Fly
・NoFall


Operation
When Fly or NoFall is detected, it will be kicked out from the server with the message "Flying is not enabled on this server."
In addition, the reason for either Fly or NoFall will be output to the log.



logs:


Caution
Fly detection will work properly only when "allow-flight" in "server.properties" is "false".
Some NoFalls are not detected (but that is only in a few cases).



How does it work?
Unlike other anti-cheats, AntiVanillaFly detects Kick Bypass movement. It also detects fake OnGround states.
Therefore, make sure to set "allow-flight = false".