The Wireless MAC Filter feature
found in Linksys wireless routers and access points allows you to control which
wireless-equipped PCs or devices may or may not communicate on your wireless
network depending on their MAC address.

When wireless clients are connecting
to a wireless network through a WRE54G Range Expander, their MAC
address is not seen by the main wireless router or access point. Instead,
the MAC address of the WRE54G is transmitted and it is considered a
client.
As a result, Wireless MAC Filtering
on the main wireless router or access point will have no effect on clients
connecting through a WRE54G Range Expander. If you have prevented a
specific computer or device from accessing the wireless network by using its
MAC address and the Prevent method, they will still be able to access the
network by connecting to the WRE54G Range Expander.
NOTE: If you specify the MAC
address of the WRE54G using the Prevent method, you will block all clients
that are connecting to the Range Expander from accessing the wireless
network. There is currently no way to specify which MAC addresses can and
cannot access the network when they are connecting via a WRE54G Range Expander.