Hard Drive based banning system?

[Coke]

Client side - event procedure used to get HD id upon client start-up
Client side - packet to send HD id upon connection to the server
Client side - packet handler to deal with HD id accepted / rejected

Server side - packet handler to associate HD id with playerindex
Server side - addition to connection accepted event procedure calling a HD id check
Server side - event procedure to read banned HD ids to file
Server side - event procedure to write banned HD ids to file
Server side - event procedure to write HD id to banned HD id list and kick and ban the player account from the server

Break a problem down, individually those are easy - google is your friend. Put some methods together, give it a go, research.

Also, if you are unsure what a Method / Event Procedure / Packet Handler is I would suggest googling them, it'll take you all of five seconds