User 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 authentication method must be MD5. 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.
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.
• Dot1x 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.)
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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