There no single fix that will keep you protected, but if you follow these steps, you’ll go a long way toward keeping out intruders. Before doing any of this, go to your Wireless router vendors website and download and install any firmware updates for the router. The firmware may have never security features built in. After you’ve installed the firmware, take these steps:
1. Regularly change the channel your router transmits over. That way, people who have tapped into it before won’t know which channel its broadcasting over. This only works if you change your SSID though, because XP automatically connects to a WiFi network, no matter what channel its on, if it knows the network’s SSID.
Log into your routers setup screen. With a Linksys router, for example, go to http://192.168.1.1 and log in by leaving the username black and, assuming you haven’t changed it from the default, entering admin as the password. Go to the Setup tab, choose new channel from the Channels drop-down list, and click the Apply button. Then restart each of your computers. Since they know all of your network names, they will automatically connect on the new channel.
2. Limit the number of IP addresses on your network to the number of computers on your network. That way, no one else will be able to get an IP address from your network’s DHCP server, and so they won’t be able to hop onto your network.
Your router’s built-in DHCP server hands out IP addresses whenever a computer needs to use the network. The router lets you set the maximum number of IP addresses it hands out. With a Linksys router, for example, go to the setup screen and click the DHCP tab. Enter the number of computers that will use your network in the “Number of DHCP Users” field, and click the Apply button. If you add another computer to your network, make sure you go back to the screen and increase the number of DHCP users by one.
3. Filter out MAC addresses. You can tell your network to only allow access to network card with specific MAC addresses. That way, only hardware that you specify can use your network. (Note that not all routers have this capability, although Linksys routers do.) Write down the MAC addresses of all the network adapters to which you’re granting network access. How you filter MAC addresses varies by router. With the Linksys WRT54G, go to the setup page and choose Advanced > Filters > Advanced. In the Advanced Wireless section, set the wireless MAC Filter to “Permit only” and then click the Edit MAC Filter List button. Then click the Wireless MAC List button and, in the list that appears, check the box under Enable MAC Filter for each of your PCs that are listed under Active PC. When you’ve done that, click the Update Filter List button. You’ll be sent back to the MAC Address Filter List windows. Click Apply button.
4. Use encryption. the WEP encryption standard is relatively weak, but it will keep out anyone except a determined expert. So turn on WEP. The WPA standard is stronger, but you can only use that if your hardware supports it. If it does, use WPA instead.
