MAC address filtering needs to
be enabled only on your wireless router, and the setup will depend on your hardware,
so consult the documentation for a how-to. Some devices will allow
you to set a couple of different 'permissions' for MAC address filtering,
permission to 'associate' with the network and permission to 'connect.'
a wireless device to communicate only with other wireless clients based on the
router, and does not allow access to the Internet or to computers that may be
connected with conventional network cable to the same router. Connecting allows
a wireless client full communication with other wired and wireless clients on
the router, and access to the Internet through the device.
4. Disabling SSID broadcasts
The SSID, or Service Set IDentifier, functions as a
sort of navigation beacon for wireless networks. In order to communicate, the wireless
router and all clients must use the same SSID value.
A wireless router or access point will broadcast this value, along with
other connection information, several times a second. Any wireless client in
range will receive these broadcasts, including the SSID, and will thus be able
to configure themselves in order to communicate on that network.
The SSID also serves to reveal the location of your network to anyone
with a wireless network adaptor, which can lead to security concerns. Several manufacturers
allow the disabling of SSID broadcasts on their wireless routers and actions
points. This increases the security of your network by making it less
visible to casual eavesdroppers and users or wireless network location software.
Doing so also requires that wireless clients must
be manually configured with the correct SSID for your network in order
to connect. This can be changed through the software that came with
the card, or through the wireless network properties in Windows XP.
Note that there are a few limitations and problems with this method. First of
all, not all devices support disabling the SSID broadcasts, so you may be
out of luck. Secondly, if you are in a business environment and
use more than one wireless router or access point and they do
not all have the SSID broadcasts disabled, you will have problems.
This is because Windows XP wireless clients will
not connect to an access point that has SSID broadcasts disabled if
there is another access point in range that is broadcasting. Bah!
Lastly, just like WEP and MAC
address filtering, this is by no means a foolproof method of hiding your
network. Even if your router has SSID broadcasts disabled, it will still
transmit the SSID information if it receives certain requests from a wireless
client... any wireless client. Certain network location software can exploit this.
DHCP, or Dynamic Host
Configuration Protocol, is the method your router uses to distribute IP addresses
and other information to its clients. Any network adaptor that is set to receive
an IP address automatically (the default setting for network adaptors in Windows) will periodically send out
a broadcast looking for a DHCP server.
If one exists, it will give that client
an IP address from a pool of addresses the DHCP server has set aside to
distribute. It will also configure other settings on the client, such as
the location of the default gateway which indicates to what address the client should
send data if it wishes to communicate with a computer outside its
current network. In the case of a home network using a wireless router, the
default gateway will be the IP address of the router itself, since it functions as the
gateway between your network and the Internet.