User's Manual

User’s Manual of SGS-5240 Series Managed Switch
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4.7.4 MAC Authentication
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.
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 involved in this authentication, and therefore, MAC-based Authentication
has nothing to do with the 802.1X standard.
The advantage of MAC-based authentication over 802.1X is that several clients can be connected to the same port (e.g.
through a 3rd party switch or a hub) and still require individual authentication, and that the clients don't need special supplicant
software to authenticate. The disadvantage is that MAC addresses can be spoofed by malicious users, equipment whose MAC
address is a valid RADIUS user can be used by anyone, and only the MD5-Challenge method is supported. The 802.1X and
MAC-based Authentication configuration consists of two sections, a system- and a port-wide.
4.7.4.1 Global Configuration
Security > MAC Authentication > Global Configuration page is used to configure MAC Authentication global.