Configuring, Managing and Troubleshooting a Firewall
Firewalls are security systems that act as a boundary between your computer or network and the external environment. Windows XP includes a firewall component named Internet Connection Firewall (ICF). Irrespective of whether your Windows XP computer attaches to the Internet via a dial-up modem, cable modem, or DSL connection, you can use ICF to protect your connection from passive or active Internet security threats.
ICF restricts the access allowed to your computer via the Internet. It should only be used if your computer is directly connected to the Internet. If your connection is via a proxy server or another firewall, ICF is not required. ICF should not be used on computers that use VPN services. It can't be enabled on private connections for host computers of ICS.
ICF is a stateful firewall, meaning that it monitors the source and destination traffic of all messages sent to the computer. ICF uses a flow table which defines protected networks. Incoming traffic is only allowed it is from a network which has an entry in the flow table. Unauthorized packets are automatically discarded.
If you initiate traffic from an ICF computer, then that traffic is logged in the table, so that if you receive inbound traffic from a site you have already contacted, that traffic is allowed to pass through.
You can configure and manage ICF as follows:
- Select Start > Control Panel and click Network Connections and right-click the connection you want to enable ICF on.
- Select Properties and click the Advanced tab. Check the Protect My Computer and Network by Limiting or Preventing Access to This Computer from the Internet option.
- Click the Settings button. In the Advanced Settings dialog box, select the Security Logging tab, then click the Log Dropped Packets option and the Log Successful Connections option. Click the OK button to finish.
Windows XP Service Pack 2 (SP2) includes Windows Firewall, a replacement for ICF. You can download an article entitled Troubleshooting Windows Firewall in Microsoft Windows XP Service Pack 2 which describes how Windows Firewall works, the common problems with using Windows Firewall, and the set of tools used to troubleshoot Windows Firewall issues.
A record of the actions you have taken to configure a firewall can contribute towards your logbook for this unit.
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