How to enable MAC address filtering on a Linksys WRT54G router

The Linksys WRT54G wireless router is capable of using many different security features, including MAC address filtering.  This article will guide you through setting up MAC address filtering on the router.

MAC address filtering can work one of two ways.  You can create a list of devices that you want to permit on your network, and any device not listed will be denied access, or you can create a list of banned devices, and as long as a device is not on that list, it will be allowed to connect to the network.

Once you've decided which method you're going to use, you'll need to get the list of MAC addresses together, whether they are the addresses to allow or exclude.  If you already have the addresses, you can skip the next paragraph.

If the devices whose MAC addresses you need are currently on your network, you can find their MAC addresses through the router.  Log in to your router's configuration software if you haven't already.  (For help with this step, see the paragraph below.)  Go to the Status tab on the far right, then beneath that click Local Network.  There will be a button labeled DHCP Clients Table; click this button and you'll see a list of all connected devices, including their MAC addresses.  If you don't know the MAC addresses that you need or how to get them, see the "Related Links" section at the end of this article for help.

When you have the MAC addresses you want to use, you are ready to set up the MAC filter.  Log in to the Linksys router software by typing the router's IP address (by default, this is 192.168.1.1) into your web browser and then entering your user name and password (if applicable).

Once you've successfully logged in, go to the Wireless tab and then beneath that, click Wireless MAC Filter.  Click the button next to Enable, and you'll see two options: "Prevent" or "Permit only."  If you want to limit certain computers from accessing your network, choose "Prevent."  If you want to allow only specified computers, choose "Permit only."  After you've made your selection, click the button below labeled Edit MAC Filter List.

Enter the MAC addresses into the filter list, with a colon (:) in between each pair of characters, just like the MAC addresses were displayed in the DHCP clients table.  (If you've forgotten a MAC address of a connected device, you can view currently-connected devices by clicking the Wireless Client MAC List button at the top of the window.)  Once you've entered all of your MAC addresses, click Save Settings.  When the "Settings are successful" message appears, click Continue.

The MAC Address Filter List window will still be open; if you're done adding addresses and you don't need to change anything, you can close it.  In the Wireless MAC Filter page that is still up, click Save Settings to enable the filter.

MAC address filtering is now in effect.  You can modify the list of addresses at any time, or disable the filter if you want.  One nice thing about the Linksys software is that if you disable the filter, the list of MAC addresses will be saved, so if you want to re-enable it later you won't have to type all of the addresses back in.

(Originally posted on Helium.com, Jan 2011)