Understanding 802.1x authentication
IEEE 802.1x is a draft standard for port-based network access control, which provides authenticated network access to 802.11 wireless networks and to wired Ethernet networks. Port-based network access control uses the physical characteristics of a switched local area network (LAN) infrastructure to authenticate devices that are attached to a LAN port and to prevent access to that port in cases where the authentication process fails.
During a port-based network access control interaction, a LAN port adopts one of two roles: authenticator or supplicant. In the role of authenticator, a LAN port enforces authentication before it allows user access to the services that can be accessed through that port. In the role of supplicant, a LAN port requests access to the services that can be accessed through the authenticator's port. An authentication server, which can either be a separate entity or co-located with the authenticator, checks the supplicant's credentials on behalf of the authenticator. The authentication server then responds to the authenticator, indicating whether the supplicant is authorized to access the authenticator's services.
The authenticators port-based network access control defines two logical access points to the LAN, through one physical LAN port. The first logical access point, the uncontrolled port, allows data exchange between the authenticator and other computers on the LAN, regardless of the computer's authorization state. The second logical access point, the controlled port, allows data exchange between an authenticated LAN user and the authenticator.
IEEE 802.1x uses standard security protocols, such as RADIUS, to provide centralized user identification, authentication, dynamic key management, and accounting.