5. Filter MAC addresses.
A MAC (Media Access Control) address is a unique identifier—like a fingerprint is to humans—that is assigned during the manufacturing of a network device, such as a network card or Wi-Fi adapter. A device’s MAC address can usually be found on a sticker often on the bottom of a device. On a computer, you can find it in the network settings. See Figure 5.
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Figure 5 MAC address filtering is a good way to limit which devices are allowed to connect wirelessly to your network.
On a Windows computer, click Start, Run, then type commfand and click OK. At the DOS prompt, type ipconfig /all and look for the Physical Address entry (see Figure 6). It’s a series of six hexadecimal numbers that look like this:
00-13-CE-32-E3-58
It can be used to keep wireless surfers out of your network. Turn on MAC address filtering in a DLink router as follows: Click Advanced tab, then the Filters button, then click on the button next to MAC Filters. Enter a name for the computer and its MAC address, and click Apply. This has to be done for each wireless device allowed on the network. (If you have a wireless TiVo box, you’ll need to add that, too.) Note that devices connected by a physical network cable to a router are exempt from MAC address filtering.
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Figure 6 Use the Windows DOS emulator to get IP and network information.