Web Management Guide-R04

Chapter 12 | Security Measures
Configuring 802.1X Port Authentication
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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 encryption method used to pass
authentication messages can be MD5 (Message-Digest 5), TLS (Transport Layer
Security), PEAP (Protected Extensible Authentication Protocol), or TTLS (Tunneled
Transport Layer Security). 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, non-EAP
traffic on the port is blocked or assigned to a guest VLAN based on the “intrusion-
action” setting. In “multi-host” mode, only one host connected to a port needs to
pass authentication for all other hosts to be granted network access. Similarly, a
port can become unauthorized for all hosts if one attached host fails re-
authentication or sends an EAPOL logoff message.
Figure 225: Configuring Port Authentication
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.