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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. (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.
The operation of dot1x 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.)
802.1x
client
1. Client attempts to access a switch port.
2. Switch sends client an identity request.
RADIUS
3. Client sends back identity information.
4. Switch forwards this to authentication server.
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.
User Authentication
3
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