A method and system for implementing LUN based hard zoning in a fiber channel network is provided. A LUN field in a Fiber Channel SCSI command frame is compared with a list of LUNS that are allowed for a particular frame source; and the frame is forwarded if the LUN is allowed for the frame source. The comparison is performed by a port receiving the frame by using an address look up table ("ALUT"). Hard zoning is based on various frame fields and/or ALUT control codes. Also provided is a method for processing a reply to a SCSI REPORT LUN command from an initiator. The method includes, intercepting a reply to a REPORT LUN command; editing the reply to remove unauthorized LUNs; and sending the edited reply to the initiator.