Evidence Cross-8/HPoE-10G, User Manual

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a port, the whole port is opened for network traffic. This allows other clients connected
to the port (for instance through a hub) to piggy-back on the successfully authenticated
client and get network access even though they really aren't authenticated. To overcome
this security breach, use the Single 802.1X variant. Single 802.1X is really not an IEEE
standard, but features many of the same characteristics as does port-based 802.1X. In
Single 802.1X, at most one supplicant can get authenticated on the port at a time.
Normal EAPOL frames are used in the communication between the supplicant and the
switch. If more than one supplicant is connected to a port, the one that comes first
when the port's link comes up will be the first one considered. If that supplicant doesn't
provide valid credentials within a certain amount of time, another supplicant will get a
chance. Once a supplicant is successfully authenticated, only that supplicant will be
allowed access. This is the most secure of all the supported modes. In this mode, the
Port Security module is used to secure a supplicant's MAC address once successfully
authenticated.

Multi 802.1X :
In port-based 802.1X authentication, once a supplicant is successfully authenticated on
a port, the whole port is opened for network traffic. This allows other clients connected
to the port (for instance through a hub) to piggy-back on the successfully authenticated
client and get network access even though they really aren't authenticated. To overcome
this security breach, use the Multi 802.1X variant.
Multi 802.1X is really not an IEEE standard, but features many of the same characteristics
as does port-based 802.1X. Multi 802.1X is - like Single 802.1X - not an IEEE standard,
but a variant that features many of the same characteristics. In Multi 802.1X, one or
more supplicants can get authenticated on the same port at the same time. Each
supplicant is authenticated individually and secured in the MAC table using the
Port
Security module.
In Multi 802.1X it is not possible to use the multicast BPDU MAC address as destination
MAC address for EAPOL frames sent from the switch towards the supplicant, since that
would cause all supplicants attached to the port to reply to requests sent from the
switch. Instead, the switch uses the supplicant's MAC address, which is obtained from
the first EAPOL Start or EAPOL Response Identity frame sent by the supplicant. An
exception to this is when no supplicants are attached. In this case, the switch sends
EAPOL Request Identity frames using the BPDU multicast MAC address as destination -
to wake up any supplicants that might be on the port.
The maximum number of supplicants that can be attached to a port can be limited
using the
Port Security Limit Control functionality.

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 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 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