Microsoft decided to included a basic functional firewall in Windows XP. This allows small companies and users who do not have a software or hardware firewall to be able to protect their computers. The firewall is called ?Internet Connection Firewall? (ICF).
Where do I find Internet Connection Firewall settings?
Open Network Connections in the Control Panel. Right-click on your Local Area Connection and choose Properties. Click on the Advanced tab.
If you check the ?Protect my computer and network by limiting or preventing access to this computer from the Internet.? it will enable ICF.Once you enable the Internet Connection Firewall, the Settings button will be available. Click on Settings to see the Advanced Settings for ICF. Here you can more finely tune ICF to work on your system. You can allow ports to be opened for the common services as shown in the picture. In addition, if you click Add, you can add an additional service not listed:
This is handy if you have a special or third party application that requires a certain port to be open.
By default, ICF prevents all outside traffic from the Internet unless it was expressly requested from your workstation (or one on your network if you are using Internet Connection Sharing).
If you click on the Security Logging tab on the dialog box you can set logging options if you want to know about dropped packets or anything.
The ICMP tab allows you to set options for ICMP requests.
If you are trying to PING a machine on the network and they have ICF enabled, you will not receive a reply. You must go to the ICMP tab and enable it to reply.
Internet Connection Firewall is a powerful tool but if it is configured incorrectly, a systems administrator may not be able to reach a machine with it turned on.