How to Set Up MAC Filtering for Wi-Fi

I've had a number of questions sent to me lately asking how to set up MAC filtering on a wireless router. I don't really recommend MAC filtering: It's relatively easy to bypass (MAC addresses can be forged) and it's a pain to use (and makes things difficult for any friends you might invite over and who you want to have access), but it doesn't really hurt. As always: Make sure you change the administrator password on your router and set up encryption on the connection, both of which provide far more critical security than MAC filtering.

A MAC address is a Media Access Control address, which is a 12-character code that uniquely identifies every piece of networking hardware ever made. The codes look like AB:4E:28:49:CC:21, 12 hexadecimal characters, separated by colons in groups of two. MAC addresses are hard-coded into network cards, Xboxes, motherboards... anything with a network connection. As such, the idea with MAC filtering is that you tell the router the MAC address of every device you want to allow on your network. Whenever something tries to connect, the router checks its MAC address list: If the MAC address doesn't show up, no access.

The first step is to collect the MAC addresses of the computers on your network. In Windows, this is easiest by doing the following: In Windows, hit Start > Run and type CMD. Then type IPCONFIG /ALL. The MAC address (or addresses) will be listed as "Physical Address" and the characters separated by hyphens. (With Vista, look under the Accessories menu for the Run command.) If you have another OS, use this handy page to find your MAC address. Write down all the MAC addresses for all your computers, and double-check them before you go to the next step.

Here's how to set it up in your router: Go to your router's configuration web page (usually by typing 192.168.0.1 in your browser, or by launching the software that you installed when you first set up the device). Look for a setting that says, well, "MAC filtering" or "MAC address control." (Remember, every router is different so I can't tell you exactly what the menu item will say.) Once you've found the MAC filtering page, simple Allow or Enable it, then start adding your MAC addresses (collected above) to the list. You're done. Reboot the router and it should be working. If a computer won't connect, you probably made a typo along the way.

Hope that helps!