Geodog

Adventures in debugging

I live with someone who, while she couldn't fairly be called at Luddite, has as much interest in how computers work as she does in the workings of a can-opener. A computer, like a can opener, is a tool -- it should just work - who cares how? Given the state of computing, she is grateful to have what she refers to as her personal MIS department.

I installed a wireless network at home about two years ago, and after seeing it work flawlessly for about 6 months, she let herself be persuaded to use it to connect to my AT&T cable modem. She loved the fast web browsing, and her connection worked flawlessly, until this week. All of a sudden, her network connection was dog slow. Web browsing was impossible. The AT&T POP3 email server kept refusing to let her pick up mail, spewing some mumbo jumbo about "name not recognized," or about "time outs." She told me, "I haven't changed anything" and gave me that "the machine is screwing up and I hate it look" that always makes me feel like I have done something wrong.

So I sat down to try and figure out what was wrong, reaching deep into the memory banks to remember the commands and configuration, since she has a Win'98 box that she doesn't want to upgrade. (It works, doesn't it? If I upgrade it to Windows 2000 for her, can I promise that everything will work? No.)

I double checked the POP3 and SMTP settings for her mail client, and re-input the user names/password. I turned off virus checking. No difference. I (painfully slowly) browsed the AT&T network status page. What a joke. I pinged Yahoo. Sure enough, I got >100ms delays, and some dropped packets. So I started with the 3 finger Ctrl-Alt-Del Windows salute, then did the winipcfg release/renew dance, then stopped and restarted the wireless card. I rebooted the router/wireless access point. No luck. I decided to try and find the network bottleneck between her computer and AT&T's mail server. Since she doesn't have any nifty windows utilities on her machine, I try and remember what the Win98 version of traceroute was. I finally get a DOS window open and type "tracert". Over 20 hops to the mailserver. "What are these idiots at AT&T doing," I think. Then I look at the hops more carefully. The first 3 have pacbell.net (California's telephone monopoly) suffixes. Slowly, the light bulb begins to glow dimly. I dash upstairs and do a traceroute from my desktop machine -- sure enough, the first three addresses have attbi.com suffixes. I log onto my router/access point, and change the SSID from "default" to "open," then run downstairs and do the same for the wireless card. Sure enough, suddenly her net connection is as fast as greased lightning, and the 86 spam messages that have accumulated for her at the server download to her machine in a flash.

Who knew that some neighbor setting up an open Wi-Fi network could screw up my open Wi-Fi network? For whatever reason, her wireless card latched onto the new weaker signal from next door in preference to the stronger one coming from my access point. I suspect we will be hearing more of these stories in the days to come, as home Wi-Fi networks become more ubiquitous. Of course this problem might have been easier to spot if I had software like Boingo's running, but our cards are so old (2 years) that they aren't supported. And who would have guessed this would be the source of the problem?