Chapter 12
| Security Measures
Configuring 802.1X Port Authentication
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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 211: Configuring Port Security
The operation of 802.1X on the switch requires the following:
◆ The switch must have an IP address assigned.
◆ RADIUS authentication must be enabled on the switch and the IP address of
the RADIUS server specified.
◆ 802.1X must be enabled globally for the switch.
◆ Each switch port that will be used must be set to dot1X “Auto” mode.
◆ Each client that needs to be authenticated must have dot1X client software
installed and properly configured.
◆ The RADIUS server and 802.1X client support EAP. (The switch only supports
EAPOL in order to pass the EAP packets from the server to the client.)
◆ The RADIUS server and client also have to support the same EAP authentication
type – MD5, PEAP, TLS, or TTLS. (Native support for these encryption methods is
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.
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