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802.1X

An IEEE standard for port-based network access control that authenticates devices before granting network access using EAP and RADIUS.

What is 802.1X?

802.1X is an IEEE standard for port-based network access control (PNAC). It provides an authentication framework for devices connecting to wired or wireless networks, ensuring only authorized users and devices gain access.

802.1X Components

  • Supplicant: Client software on the connecting device
  • Authenticator: Network device (switch, access point) controlling access
  • Authentication Server: Typically a RADIUS server verifying credentials

How 802.1X Works

  1. Device connects to network port (port starts blocked)
  2. Authenticator requests identity
  3. Supplicant provides credentials via EAP
  4. Credentials forwarded to authentication server
  5. Server validates and responds (accept/reject)
  6. Authenticator opens port or denies access

EAP Methods

  • EAP-TLS: Certificate-based, most secure
  • PEAP: Password with TLS tunnel
  • EAP-TTLS: Tunneled TLS authentication
  • EAP-FAST: Cisco's flexible authentication

Benefits

  • Strong authentication before network access
  • Dynamic VLAN assignment per user
  • Support for wired and wireless networks
  • Integration with existing directory services
  • Granular access control