Proceed with Caution: Consumer Wireless Networks - 30 Oct 2003

Recently, I've revisited the wireless networking I've been using in my home office. Even though wireless is fun and simple to implement, I use wired connections that support speeds as fast as Gigabit Ethernet throughout my home. Computer aficionado that I am, I have computers in just about every room. I was interested in comparing the performance of the effective range of my built-in wireless capability in notebooks with that of PC Card adapters.

Built-in wireless capability in notebooks has a significant performance advantage over PC Cards. This advantage results from the fact that most manufacturers place wireless antennas on the notebook's LCD frame, whereas small antennas must be incorporated into PC Cards. As a result, wireless antennas have a much wider range than PC Card antennas do. Wireless antennas also do a better job of handling various signal problems. (I found that built-in wireless NICs are significantly better than PC Cards at picking up signals in areas where the PC Cards couldn't even see a network.)

The curious thing about my project is that I picked up intermittent wireless network connections even when I hadn't powered up my Access Point (AP). My initial thought about this situation was that I must have left a wireless device connected somewhere on my network. However, when I ran down every connection and did some IP address scanning, I couldn't find any unaccounted-for connections. The wireless connection disappeared as mysteriously as it appeared. I considered the possibility that I was picking up a neighbor's wireless connection, but the closest house to mine is about 150 yards away, and I thought that such an unintentional connection would be unlikely given the quality of consumer-grade wireless APs.

I then decided to make some configuration changes to the wireless AP I was using for testing, a Belkin F5D6130 802.11b AP. I installed the management software on my desktop computer, and when the application scanned for APs, it found not only the AP I had set up but also a second AP running on a different network. Realizing that I was picking up a neighbor's AP, I tried logging on to it using the default password. Sure enough, I connected.

Interestingly, this happened on a rainy, overcast day. On a bright, clear day I can't see this second AP on my network, and I have yet to figure out which of my neighbors is using the same hardware I'm using. What is truly weird is that I was able to change the configuration of the other AP. Because I could see the AP on my network, I noticed that it was generating an IP address conflict. Despite being configured for DHCP, the AP set itself to 192.168.0.1, conflicting with my network gateway address. I set the static IP address to the vendor-provided default of 192.168.0.254.

I've talked to my closest neighbors, and none are using wireless networking. My best guess is that atmospheric conditions are letting me pick up a network from more than 300 yards away. I'm not interested in trying to crack my neighbor's network, but using the default password on an AP without any sort of encryption or authentication is a bad idea. This situation has made me wonder how many out-of-the-box wireless connections are running in neighborhoods across the country, not to mention why consumer wireless vendors don't set their defaults to require some level of security.

 

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