Windows Firewall
Windows Defender Firewall inWindows 11, reporting firewall is turned on and working normally.
Other names	Microsoft Defender Firewall Windows Defender Firewall Internet Connection Firewall
Developer	Microsoft
Operating system	Windows XP SP2 and later Windows Server 2003 SP1 and later
Service name	MpsSvc
Type	Personal firewall
Website	learn.microsoft.com/en-us/windows/security/operating-system-security/network-security/windows-firewall/

Windows Firewall (officially calledMicrosoft Defender Firewall inWindows 10 version 2004 and later) is afirewall component of Microsoft Windows. It was first included inWindows XP x86 SP2,Windows XP x64, andWindows Server 2003 SP1.^[1][2][3] Before the release of Windows XP Service Pack 2, it was known as the "Internet Connection Firewall."

When Windows XP was originally shipped in October 2001, it included a limited firewall called "Internet Connection Firewall". It was disabled by default due to concerns with backward compatibility, and the configuration screens were buried away in network configuration screens that many users never looked at. As a result, it was rarely used. In mid-2003, theBlaster worm attacked a large number of Windows machines, taking advantage of flaws in theRPC Windows service.^[1] Several months later, theSasser worm did something similar. The ongoing prevalence of these worms through 2004 resulted in unpatched machines being infected within a matter of minutes.^[4] Because of these incidents, as well as other criticisms that Microsoft was not being active in protecting customers from threats, Microsoft decided to significantly improve both the functionality and the interface of Windows XP's built-in firewall, rebrand it as Windows Firewall,^[5] and switched it on by default since Windows XP SP2.

One of three profiles is activated automatically for each network interface:^[6]

• Public assumes that the network is shared with the World and is the most restrictive profile.
• Private assumes that the network is isolated from the Internet and allows more inbound connections thanpublic. A network is never assumed to beprivate unless designated as such by a local administrator.
• Domain profile is the least restrictive. It allows more inbound connections to allow for file sharing etc. Thedomain profile is selected automatically when connected to a network with a domain trusted by the local computer.

Security log capabilities are included, which can recordIP addresses and other data relating to connections originating from the home or office network or the Internet. It can record both dropped packets and successful connections. This can be used, for instance, to track every time a computer on the network connects to a website. This security log is not enabled by default; the administrator must enable it.^[7]

Windows Firewall can be controlled/configured through aCOM object-oriented API, scriptable through thenetsh command,^[8] through theGUI administration tool^[9] or centrally throughgroup policies.^[10] All features are available regardless of how it is configured.

In the unreleasedWindows Neptune, the firewall was introduced^{[citation needed]}. It is similar to the one found in Windows XP.^[11]

Windows Firewall was first introduced as part of Windows XP Service Pack 2. Every type of network connection, whether it is wired, wireless, VPN, or even FireWire, has the firewall enabled by default, with some built-in exceptions to allow connections from machines on the local network. It also fixed a problem whereby the firewall policies would not be enabled on a network connection until several seconds after the connection itself was created, thereby creating a window of vulnerability.^[12] A number of additions were made toGroup Policy, so that Windows system administrators could configure the Windows Firewall product on a company-wide level. XP's Windows Firewall cannot block outbound connections; it is only capable of blocking inbound ones.

Windows Firewall turned out to be one of the two most significant reasons (the other beingDCOM activation security)^[13] that many corporations did not upgrade to Service Pack 2 in a timely fashion. Around the time of SP2's release, a number of Internet sites were reporting significant application compatibility issues, though the majority of those ended up being nothing more than ports that needed to be opened on the firewall so that components of distributed systems (typically backup and antivirus solutions) could communicate.

Windows Firewall addedIPv6, which was not supported by its predecessor, Internet Connection Firewall.^[14]

Windows Vista improved the firewall to address a number of concerns around the flexibility ofWindows Firewall in a corporate environment:^[15]

• The firewall is based on theWindows Filtering Platform.
• A newmanagement console snap-in namedWindows Firewall with Advanced Security which provides access to many advanced options, and enables remote administration. This can be accessed via Start -> Control Panel -> Administrative Tools -> Windows Firewall with Advanced Security, or by running "wf.msc"
• Outbound packet filtering, reflecting increasing concerns aboutspyware andviruses that attempt to "phone home". Outbound rules are configured using the management console. Notifications are not shown however for outbound connections.
• With the advanced packet filter, rules can also be specified for source and destination IP addresses and port ranges.
• Rules can be configured for services by its service name chosen by a list, without needing to specify the full path file name.
• IPsec is fully integrated, allowing connections to be allowed or denied based on security certificates,Kerberos authentication, etc. Encryption can also be required for any kind of connection.
• Improved interface for managing separate firewall profiles. Ability to have three separate firewall profiles for when computers are domain-joined, connected to a private network, or connected to a public network (XP SP2 supports two profiles—domain-joined and standard). Support for the creation of rules for enforcing server and domain isolation policies.

Windows Server 2008 contains the same firewall as Windows Vista. The firewall inWindows Server 2008 R2 andWindows 7 contains some improvements, such as multiple active profiles.^[16]

Changes to this component in Windows 10 are:

• The change of name to Windows Defender Firewall that occurred in the September 2017 update, known as theFall Creators Update (codename Redstone 3).
• Firewall service (mpssvc) cannot be stopped anymore.

Windows Firewall maintains a log file at "%windir%\system32\logfiles\firewall\pfirewall.log" by default. This log file can be viewed with any text editor, such asNotepad. Specialized tools likeFirewall Log Viewer for Windows offer a more user-friendly interface and additional features for analyzing these logs.

• List of Microsoft Windows components
• Security and safety features new to Windows Vista
• Personal firewall

1. ^ These multiple vulnerabilities were fixed by Microsoft over the course of several months; Microsoft security bulletinsMS03-026,MS03-039, andMS04-012 cover this in more detail.

• Windows Firewall with Advanced Security onMicrosoft TechNet

• Windows components
• Firewall software
• Microsoft Windows security technology

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• Articles with unsourced statements from April 2018