User’s Manual of GS-4210-16T2S_24T2S_16P2S_24P2S_48T4S
4.9.2 802.1X
Overview of 802.1X (Port-based) Authentication
In the 802.1X-world, the user is called the supplicant, the switch is the authenticator, and the RADIUS server is the
authentication server. The switch acts as the man-in-the-middle, forwarding requests and responses between the supplicant
and the authentication server. Frames sent between the supplicant and the switch are special 802.1X frames, known as EAPOL
(EAP Over LANs) frames. EAPOL frames encapsulate EAP PDUs (RFC3748). Frames sent between the switch and the
RADIUS server are RADIUS packets. RADIUS packets also encapsulate EAP PDUs together with other attributes like the
switch's IP address, name, and the supplicant's port number on the switch. EAP is very flexible, in that it allows for different
authentication methods, like MD5-Challenge, PEAP, and TLS. The important thing is that the authenticator (the switch) doesn't
need to know which authentication method the supplicant and the authentication server are using, or how many information
exchange frames are needed for a particular method. The switch simply encapsulates the EAP part of the frame into the
relevant type (EAPOL or RADIUS) and forwards it.
When authentication is complete, the RADIUS server sends a special packet containing a success or failure indication. Besides
forwarding this decision to the supplicant, the switch uses it to open up or block traffic on the switch port connected to the
supplicant.
Overview of User Authentication
It is allowed to configure the Managed Switch to authenticate users logging into the system for management access using local
or remote authentication methods, such as telnet and Web browser. This Managed Switch provides secure network
management access using the following options:
Remote Authentication Dial-in User Service (RADIUS)
Terminal Access Controller Access Control System Plus (TACACS+)
Local user name and Priviledge Level control
4.9.2.1 Understanding IEEE 802.1X Port-based Authentication
The IEEE 802.1X standard defines a client-server-based access control and authentication protocol that restricts unauthorized
clients from connecting to a LAN through publicly accessible ports. The authentication server authenticates each client
connected to a switch port before making available any services offered by the switch or the LAN.
Until the client is authenticated, 802.1X access control allows only Extensible Authentication Protocol over LAN (EAPOL)
traffic through the port to which the client is connected. After authentication is successful, normal traffic can pass through the
port.
This section includes this conceptual information:
• Device Roles
• Authentication Initiation and Message Exchange
• Ports in Authorized and Unauthorized States
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