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Security Fundamentals & Crypto · Foundational

IEEE 802.1X

Port-based network access control standard that authenticates devices before allowing traffic on wired or wireless networks.

Definition

802.1X uses three roles: the supplicant (client), the authenticator (switch or access point), and the authentication server (usually RADIUS). EAP messages are carried over EAPOL between supplicant and authenticator, and over RADIUS to the server. Until authentication succeeds, the port allows only EAPOL traffic.

Example

A switch port configured with 'authentication port-control auto' blocks a laptop until it authenticates via EAP-TLS.

Exam tip

Know the three roles; the authenticator relays but does not make the decision.

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