Interlogix NS3502-8P-2S User Manual - Manual (Page 228)

IFS NS3502-8P-2S User Manual
228
4.11 Authentication
This section is to control the access of the Managed Switch, includes the user access and management
control.
The Authentication section contains links to the following main topics:
 IEEE 802.1X Port-Based Network Access Control
 MAC-Based Authentication
 User Authentication
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 is 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 MAC-Based Authentication
Unlike 802.1X, MAC-based authentication is not a standard, but merely a best-practices method
adopted by the industry. In MAC-based authentication, users are called clients, and the switch acts as
the supplicant on behalf of clients. The initial frame (any kind of frame) sent by a client is snooped by
the switch, which in turn uses the client's MAC address as both username and password in the
subsequent EAP exchange with the RADIUS server. The 6-byte MAC address is converted to a string on
the following form "xx-xx-xx-xx-xx-xx", that is, a dash (-) is used as separator between the lower-cased
hexadecimal digits. The switch only supports the MD5-Challenge authentication method, so the
RADIUS server must be configured accordingly.
When authentication is complete, the RADIUS server sends a success or failure indication, which in turn
causes the switch to open up or block traffic for that particular client, using static entries into the MAC
Table. Only then will frames from the client be forwarded on the switch. There are no EAPOL frames