A multiple key, multiple tiered network security system, method and apparatus provides at least three levels of security. The first level of security includes physical (MAC) address authentication of a user device being attached to the network, such as a user device being attached to a port of a network access device. The second level includes authentication of the user of the user device, such as user authentication in accordance with the IEEE 802.1x standard. The third level includes dynamic assignment of a user policy to the port based on the identity of the user, wherein the user policy is used to selectively control access to the port. The user policy may identify or include an access control list (ACL) or MAC address filter. Also, the user policy is not dynamically assigned if insufficient system resources are available to do so. Failure to pass a lower security level results in a denial of access to subsequent levels of authentication.