Administrator's Guide - Kerio Software Archive

8.2 MAC address filtering
Figure 8.3
MAC address filtering
Filtering mode
The MAC address filter works in two modes:
• Blocking of computers with listed MAC addresses.
The filter will block only traffic of computers (devices) with MAC addresses
included on the list. Traffic will be allowed for any other computers. This mode
can be used for quick blocking of certain MAC addresses but it does not protect
from connection of new, unknown devices. Another deficit is that many systems
and devices allow change of their network adapter’s MAC address.
• Allowing of traffic of computers with listed MAC addresses.
The filter allows only traffic of computers with MAC addresses included on the
list, any other traffic will be blocked. This filtering mode is very effective as all
unknown MAC addresses are blocked (in one physical network cannot include
more than one device with an identical MAC address — misuse of allowed MAC
address is very difficult or even impossible).
However, for this purpose, it is necessary to create and maintain a complete list
of MAC addresses of all devices with traffic allowed. This can be quite demanding
in case of larger networks.
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