| By Fred Langa |
When the Web becomes unreachable, it’s time to start digging into your router and firewall settings.
When your system’s port 80 is blocked, all http: traffic stops, and you’ll need to do a bit of cyber-sleuthing to learn the cause.
What’s blocking my PC’s port 80 connections?
Sergio Geralnik encountered a mysterious Web-traffic jam:
- “My wife’s computer suddenly can’t hit any Web sites. Any program that tries to communicate via http: using port 80 is getting communication errors. All the other computers using this router and the same Internet connection work fine. I’ve tried scanning for viruses and malware, but nothing has come up. Any suggestions?”
If the PC is connected OK, check that only one firewall is operating on the malfunctioning PC. Firewalls don’t play nice together — only one firewall should be active on your system at any given time.
Next, check that the firewall is running properly. Drill down into the firewall’s settings — including any custom “rules” or “exceptions” — to see whether something has explicitly blocked port 80. Various firewalls handle these custom settings differently, so you may need to check the program’s help file for information on how to verify them.
For help with XP’s built-in firewall, see Microsoft Knowledge Base article 308127, “How to manually open ports in Internet Connection Firewall in Windows XP.” To read about Vista’s firewall settings, browse to the Windows Help and How-to article, “Open a port in Windows Firewall.”