I'm relatively confident that a whitelist bypass like that has been impossible since Minecraft 1.3. (2013 ish). The login handshake for an online-mode (authenti

I'm relatively confident that a whitelist bypass like that has been impossible since Minecraft 1.3. (2013 ish). The login handshake for an online-mode (authentication enabled) server involves a three way communication between the client, the server, and Mojang's auth server, which basically involves the client telling the server "hey, I'd like to join", then the server acknowledging, the client telling Mojang "hey, I'm attempting to connect to this particular server" here are my login credentials", then telling the server "hey, I go ask Mojang, I'm trying to connect", and then the server checking with Mojang that this given user is trying to connect to this particular server, then establishing an encrypted connection to the client.