Windows Firewall is a built-in, host-based, stateful firewall that is included in Windows Vista, Windows Server 2008, Windows XP with Service Pack 2 and later, and Windows Server 2003 with Service Pack 1 and later. Windows Firewall drops incoming traffic that does not correspond to either traffic sent in response to a request of the computer (solicited traffic) or unsolicited traffic that has been specified as allowed (excepted traffic). Windows Firewall helps provide protection from malicious users and programs that rely on unsolicited incoming traffic to attack computers. In Windows Vista and Windows Server 2008, Windows Firewall can also drop outgoing traffic and is configured using the Windows Firewall with Advanced Security snap-in, which integrates rules for both firewall behavior and traffic protection with Internet Protocol security (IPsec).
Networking at a Glance