Peter's Blog

I went to visit someone to help with a problem using broadband. When using Internet Explorer they got errors to say the web site could not be found. The system had been like this for three or four weeks. They got on to BT technical support who went through the checklist and could find no problem. They told the victim to reinstall Internet Explorer or to try Firefox. They did both but still no joy. BT Tech support told them to try reinstalling IE again and if that didn't work complain to Microsoft as the system was running Windows XP home edition.

I did the following:

• From connections I started a connection to the internet. It seemed to connect ok, no errors.
• Looked in connection TCP/IP properties and it was set to use DHCP. Nothing unusual, not as if the DNS settings were wrong.
• I opened a command prompt and tried:

  nslookup google.com
  

  This found google.com so indeed DNS was fine and the connection was working (it found the DNS server).
• I opened IE and Firefox and they gave errors as if there were no connection (like when wifi fails).
• I looked in Firefox connection settings and they were fine, direct connection to the internet, no strange proxies or anything.
• Thought about how the connection could possibly be broken and suddenly thought firewall. Looked around and found Norton Personal Firewall installed. I opened it up and it was complaining that the subscription had lapsed. I disabled it and Firefox and IE worked fine.
• The PC was running XP SP1, automatic updates were disabled. Decided to go into windows update and try to get SP2. While downloading 30 pending critical security updates over the course of an hour the Norton thing kept moaning about break-in attempts, all trying to use a buffer overflow to break into a DOM RPC port (port number four hundred and something). Norton kept waving a dialog that had to be ok'ed.
• Installed all the updates. It didn't offer to upgrade to SP2 but I remembered how to enable the firewall in SP1 (hidden in connection properties) so I enabled it. Didn't see any more break in attempts. I think the same firewall is present in SP2, they just turned it on by default and made it more prominent.
• Enabled automatic windows update.

Morals:

• Norton firewall breaks your internet connection if you stop paying for it.
• Windows really needs firewalling