What is 802.1X network authentication?
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Answer
802.1X is an IEEE standard for port-based Network Access Control (NAC) that requires authentication before allowing network access. When a device connects to a switch port or Wi-Fi access point, it cannot access the network until it provides valid credentials. Components: Supplicant (the client device needing access), Authenticator (the switch or WAP enforcing access), Authentication Server (RADIUS server, e.g., Cisco ISE, FreeRADIUS, Microsoft NPS — validates credentials). The process: supplicant provides credentials (username/password, certificate, or EAP method) via EAP (Extensible Authentication Protocol). The authenticator forwards to the RADIUS server. If approved, the port is opened; if denied, traffic is blocked or placed in a guest VLAN. 802.1X provides: strong authentication (certificates), per-user/device policies (VLAN assignment based on identity), and visibility into what is on the network. Essential for enterprise network security.
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