A firewall is software or hardware that creates a protective barrier between your computer and potentially damaging content on the Internet or network. The firewall helps to guard your computer against malicious users, and also against malicious software such as computer viruses and worms. Microsoft Windows XP helps to provide more security in the form of a firewall that is known as the Internet Connection Firewall (ICF). Windows XP Service Pack 2 (SP2) includes the new Windows Firewall, which replaces the ICF.

The firewall feature in Windows XP is designed for home and small business use. ICF and Windows Firewall help to provide more protection for computers that are directly connected to the Internet. This feature is available for local area network (LAN), for high-speed Internet connections, and for dial-up Internet connections. The firewall feature also helps to prevent the scanning of ports and of resources, such as file and printer shares, from external sources.

This article discusses how to enable ICF in Windows XP or in Windows XP SP1, and also how to enable Windows Firewall in Windows XP SP2. This article also discusses how to disable the Internet Connection Firewall feature in Windows XP or in Windows XP SP1, and how to disable Windows Firewall in Windows XP SP2. Disabling the firewall may help you to troubleshoot applications that do not function as expected behind a firewall.

For more information about the changes in Windows Firewall in Windows XP SP2, see New Networking Features in Windows XP Service Pack 2 (http://www.microsoft.com/technet/community/columns/cableguy/cg0104.mspx), the January 2004 Cable Guy article.

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Enable Internet Connection Firewall in Windows XP or Windows XP SP1

The firewall feature can be useful when you want to protect a dial-up connection when dialing directly into an Internet service provider (ISP), or to protect a LAN connection that is connected to an asymmetric digital subscriber line (ADSL) or cable modem. You can also enable the firewall feature on the Internet connection of an Internet Connection Sharing (ICS) host computer to provide protection to the ICS host computer.

To enable Internet Connection Firewall feature using the Network Setup Wizard in Windows XP or Windows XP SP1:

1.	Run the Network Setup Wizard. To access this wizard, point to Control Panel, double-click Network and Internet Connections, and then click Setup or change your home or small office network.
2.	The Internet Connection Firewall is enabled when you choose a configuration in the wizard that indicates that your computer is connected directly to the Internet.

To configure Internet Connection Firewall manually in Windows XP or Windows XP SP1:

1.	Click Start, click Run, type control.exe netconnections, and then click OK.
2.	Right-click the connection on which you would like to enable ICF, and then click Properties.
3.	On the Advanced tab, click the box to select the option to Protect my computer or network.
4.	If you want to enable the use of some applications and services through the firewall, you must enable them. To do this, click Settings, and then click to select the programs, protocols, and services that you want to enable for the ICF configuration.

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Enable Windows Firewall in Windows XP SP2

1.	Click Start, click Run, type Firewall.cpl, and then click OK.
2.	On the General tab, click On (recommended), and then click OK.

Disable Internet Connection Firewall in Windows XP or Windows XP SP1

Note A firewall is designed to help protect your computer from attack by malicious users or by malicious software. Malicious software includes viruses that use unsolicited incoming network traffic to attack your computer. Before you disable your firewall, you must disconnect your computer from all networks, including the Internet. To do this, follow these steps:

1.	In Control Panel, double-click Networking and Internet Connections, and then click Network Connections.
2.	Right-click the connection on which you want to disable ICF, and then click Properties.
3.	On the Advanced tab, click to clear the Protect my computer or network check box.

Disable Windows Firewall in Windows XP SP2

Note A firewall is designed to help protect your computer from attack by malicious users or by malicious software. Malicious software includes viruses that use unsolicited incoming network traffic to attack your computer. Before you disable your firewall, you must disconnect your computer from all networks, including the Internet. To do this, follow these steps:

1.	Click Start, click Run, type Firewall.cpl, and then click OK.
2.	On the General tab, click Off (not recommended), and then click OK.

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