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User’s Manual of SGSD-1022 / SGSD-1022P
SGSW-2840 / SGSW-2840P
279
4.11.8 802.1X 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 Managed 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.
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. (Some
clients have native support in the operating system, otherwise the dot1x client must support the required authentication
method.)