Hello, Would it be possible for a plugin to send a client a custom packet to request their jar / version information? I was thinking of using ProtocolLib but I wouldn't know where to start. Thanks.
I get that you're trying to check the clients version... A simple Google search and I found this: https://bukkit.org/threads/question-how-to-check-client-game-version.318071/
You cán indeed check for the client's MC version, like Raydond said, but you can't check the version name, and even if you wrote a custom packet and sent it to the client, it won't work: If a client recieves an unknown packet it crashes.
The client jar they connect with, like if someone joins it would say, "<Player> has joined, connecting with 'minecraft-hacked-jar-183.jar'", etc.
@nbrandwine wiki.vg/protocol There is a list of every packet you can send, where on there is "PacketPlayInClientMCClient" or something of that nature? Even then, this would be a hilariously bad check, because all a hacked client has to do is respond with the vanilla MC packet.