How Secure Is Your Wireless Network? Safeguarding Your Wi-Fi LAN

802.1x Authentication Conversation

Here's how authentication works (Figure 6.3):

Figure 6.3. 802.1x protocol.

The supplicant (client) starts by sending an EAP Start frame. This lets the authenticator know that somebody's knocking and wants in. The authenticator replies with an EAP Request/Identity frame, which is like saying, “Who's there?” The supplicant replies with another EAP Request/Identity frame identifying themselves (i.e., a username). The authenticator forwards this information to the authentication server.

The authentication server then sends the authenticator an EAP-Request frame which contains some kind of challenge or request for ...