Here's the complex deal; the ID's aren't the same in client than in server.
The only way I found to recognize clients are via the username.
WRONG. GML is a scripting language. GM is not. GML is not GM.
GML = Game Maker Language
Got it now? lol
Oh, and the other thing that John said...
Well, I only send the password once, and it's when a client tries to login into the server. So yeah, I'm doing what you say; sending it one-way. The previous packet is for asking the client to send the password.