How to build a wireless network

Step 7: Other methods of security

Encrypting your network is one way of keeping strangers off your network, but it also slows down overall throughput slightly due to decryption overheads. Another method of security your network is to use MAC (Media Access Control) security, which restricts WLAN access to a set of known devices.

Every network-connectable product in the world ships with its own unique MAC address. To find your notebook's MAC address -- note that this is the address of its wireless network card, not its Ethernet adapter -- click Start, Control Panel, Network Connections, then double-click on Wireless Network Connection, click Support, and click Details. The Physical Address label -- a series of six pairs of hexadecimal numbers (0 through F) -- is your MAC address.

You will also need the MAC address of any phones, PDAs or other wireless devices you intend to connect to your network; refer to your device's instructions to find out where you can locate this information.

Once you've gathered the MAC addresses of each device you want allowed onto the WLAN, log onto your WLAN AP, then choose Wireless/Wireless MAC Filter and, in our case, click on Enable. Click on Edit MAC Filter List, then type in each of the addresses -- carefully - to the list.

Save your changes, then click on the Permit Only option so that only the devices you've chosen can get onto the network. You can also ban specific devices by choosing the Prevent option, but this can be hard to police unless you live inside a lead house and can control what devices other people have.

Just remember: no other devices will be allowed onto your WLAN. This means if a friend visits and wants to get online with her notebook, you'll need to find out its MAC address and manually add it to the WLAN AP setup.

MAC filtering is another way to restrict access to your network

Step 8: Plug in other devices

If you have any other wired devices -- for example, a Voice over IP phone -- you probably already have an Ethernet switch or hub installed. Unplug the devices from that switch or hub, then plug them into the other ports on the back of the WLAN AP. You won't need the old switch or hub anymore (unless you have more than four devices to plug into the WLAN AP, in which case you can plug the old switch or hub into a port on the WLAN AP).

Plug the lead from your ADSL or cable modem into the jack on the left, and your fixed devices into the four switched ports on the right.