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14-1
Chapter 14: Configuring 802.1X Port
Authentication
Network switches can provide open and easy access to network resources by
simply attaching a client PC. Although this automatic configuration and access is a
desirable feature, it also allows unauthorized personnel to easily intrude and
possibly gain access to sensitive network data.
The IEEE 802.1X (dot1x) standard defines a port-based access control procedure
that prevents unauthorized access to a network by requiring users to first submit
credentials for authentication. Access to all switch ports in a network can be
centrally controlled from a server, which means that authorized users can use the
same credentials for authentication from any point within the network.
This switch uses the Extensible Authentication Protocol over LANs (EAPOL) to
exchange authentication protocol messages with the client, and a remote RADIUS
authentication server to verify user identity and access rights. When a client (i.e.,
Supplicant) connects to a switch port, the switch (i.e., Authenticator) responds with
an EAPOL identity request. The client provides its identity (such as a user name) in
an EAPOL response to the switch, which it forwards to the RADIUS server. The
RADIUS server verifies the client identity and sends an access challenge back to the
client. The EAP packet from the RADIUS server contains not only the challenge, but
the authentication method to be used. The client can reject the authentication
method and request another, depending on the configuration of the client software
and the RADIUS server. The authentication method must be MD5. (TLS, TTLS and
PEAP will be supported in future releases.) The client responds to the appropriate
method with its credentials, such as a password or certificate. The RADIUS server
verifies the client credentials and responds with an accept or reject packet. If
authentication is successful, the switch allows the client to access the network.
Otherwise, network access is denied and the port remains blocked.
802.1x
client
RADIUS
server
1. Client attempts to access a switch port.
2. Switch sends client an identity request.
3. Client sends back identity information.
4. Switch forwards this to authentication server.
5.Authentication server challenges client.
6. Client responds with proper credentials.
7.Authentication server approves access.
8. Switch grants client access to this port.