Verify or Enable the Firewall in Windows

Windows XP incorporates its own firewall. It's called "Internet Connection Firewall" (ICF) for plain vanilla XP, and "Windows Firewall" for SP2. Both check incoming replies -- from Web sites, email servers, etc. -- against outgoing requests. They only allow the ones that are genuine responses to go on to your programs.

These firewalls are both stealthy, which means they just play dead when they get a incoming request or reply that does not match an outgoing request. That makes your computer more or less invisible on the Internet.

Both are fairly effective firewalls, but they're also a primary hacking target because they're so ubiquitous. There are indications that "Windows Firewall" is more susceptible to attack (being disabled) than third-party firewalls.

Verify, enable of disable Windows Firewall

Go to the section below for ICF if you do not have SP2 installed.

Enable or disable Windows Firewall from the new Security Center in Windows XP - SP2. [Start > Control Panel > Security Center] You'll find a link -- Windows Firewall -- down at the bottom of the Security Center window. That takes you to the dialog box for managing Windows Firewall.

Verify, enable or disable ICF

Plain Windows XP also provides good instructions for enabling or disabling ICF: Click "Start" > "Help and Support" > and then enter "firewall" in the Search box.

Then click the green arrow > and pick "Enable or disable Internet Connection Firewall" in the search results. You may want to click the "Print" button to get a copy of the instructions that appear. Now you can enable the firewall

Or, you can follow my instructions here.

1. Click "Start" > click "Control Panel" > right-click "Network Connections" and choose "Open". The "Network Connections" dialog box should open.
2. Right-click the connection(s) that you use and select "Properties". It will probably have the name of your ISP on it if it's dial-up, and it will indicate "Local Area Connection" if it's DSL or Cable.
3. Select the "Advanced" -- not Security -- tab in the dialog box that opens.
4. Check the "Protect my computer and network by limiting or preventing access to this computer from the Internet" option to enable the ICF. Uncheck it to disable the ICF.