Norton Internet Security

Last night I was asked to debug a problem with a Windows XP laptop that had Norton Internet Security installed. The problem? “The internet didn’t work.” Unfortunately I didn’t realize about Norton Internet Security part until later. While the fix was simple, disable Norton Internet Security, the symptoms of the problem weren’t obvious to me.

Connection acquisition wasn’t a problem “ipconfig /release” and “ipconfig /renew” just worked. Pinging IPs worked but pinging hostnames failed. Putting and IP in the browser like worked. I thought… classic dns issue. “ipconfig /flushdns” should just solve it. Wrong. I was really surprised when “nslookup” worked. So I could resolve hostnames to IPs, I can connect to IPs but when I put it all together it fails.

At this point Safe Mode with Networking to the rescue. In safe mode everything just works. Clearly something starts up in regular mode that screws up the connection. Not seeing Norton Internet Security Icon in the in taskbar in regular mode, because it’s hidden, I went the msconfig route. Disabling everything possible and restarting still didn’t solve the problem.

The lesson here was that Norton gets it’s claws so deep into the system that it’s not obvious it’s running at all, when in fact it is and the firewall itself can act in pretty unintuitive ways.