iES28TG/iES28GF User Manual
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iS5 Communications Inc.
4.
MAC-based
Auth.
Unlike port-based 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 in 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 the Port Security module. 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 port-based 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. Another advantage of MAC-based
authentication over 802.1X-based authentication is that the clients do not 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. Also, only the MD5-Challenge
method is supported. The maximum number of clients that can be attached to a
port can be limited using the Port Security Limit Control functionality.
Port State
The current state of the port. It can undertake one of the following values:
Globally Disabled
: NAS is globally disabled.
Link Down
: NAS is globally enabled, but there is no link on the port.
Authorized
: the port is in Force Authorized or a single-supplicant mode and the
supplicant is authorized.
Unauthorized:
the port is in Force Unauthorized or a single-supplicant mode and
the supplicant is not successfully authorized by the RADIUS server.
X Auth/Y Unauth
: the port is in a multi-supplicant mode. Currently X clients are
authorized and Y are unauthorized.
