Concept 802.1X

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[edit] Info

802.1X, Port-Based Network Control, is an IEEE standard. The standard allows LAN devices (wired network cabling![1]) to perform an authentication handshake within the 802.3 link layer (Ethernet). The authentication is encapsulated within EAP over LAN (EAPOL) frames. No other traffic, except EAPOL is allowed prior to a successful authentication[2][3].

The standard specifies the following parties participating in an 802.1X authentication:

  • Supplicant: The party supplying credentials towards an authenticator on the other side of a point-to-point link. An IP phone fulfills a supplicant's role.
    • innovaphones' IP phones are configured to support pass-through of EAPOL messages. A PC attached to the PC-port of a phone may also become a supplicant and may 802.1X-authenticate independently and separately[4].
  • Authenticator: The party facilitating the authentication. A switch will usually be the authenticator.
  • Authentication Server: The party providing the authentication service to the authenticator. The 802.1X standard mentions a RADIUS server to be an authentication server.

It is the Authenticator/Authentication Server deciding whether EAP-MD5 or EAP-TLS is going to be applied.

  • Sample Protocol Flow, EAP-MD5:

Image:802dot1x-EAPOL-640x480.gif

  • Sample Protocol Flow, EAP-TLS:

Image:IP240-eap-tls-success.PNG

[edit] Notes

  1. The standard refers to 802 LANs as a whole, including shared media such as 802.11 WLANs. However, only 802.3 LANs are targeted by the functionality discussed in this article.
  2. It is an authenticator's task to guarantee that non-EAPOL traffic won't be forwarded before an authentication succeeded.
  3. 802.1X must not be considered a bullet-proof security mechanism, since all traffic following the authentication phase is not authenticated.
  4. Major authenticators do support multi-auth authentication

Howto article: 802.1X EAP-TLS With FreeRadius

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