It is not possible in a vanilla client to 'scan a user's files', but there has been an exploit in older versions of Minecraft, before 1.9, to check if a certain file exists on a user's computer ( ). You can actually fake this if you want, but obviously it would result in some issues. This means that all clients on 1.8.x can join any server on 1.8.x. They can only tell if the client will be compatible with the server or not, because the 'protocol version' is compared when joining a server. They can detect versions and kick people that use the wrong version. 4 I turned on XRay and the ores are showing everywhere! Can they find out about client-side render mods?.Spoutcraft), they can force vanilla clients. 3 If they can force Spigot clients (e.g.2 They disabled my radar in Rei's minimap!!!.
