Almost everyone using Windows has seen it. When you launch an application or game, Windows Firewall will display a message stating that some features of this app have been blocked. What does this mean and should you allow access?
Why is this message displayed?
This message is displayed when an application wants to act as a server and accept incoming connections. This prompt does not appear for most of the applications you use, such as Web browsers and e-mail clients. It is displayed only for certain application types, such as For media servers, multiplayer games, online file sharing tools, and other server applications.
The Windows Firewall blocks incoming connections by default. If the connection to a new application is blocked for the first time, this message appears. You can then choose whether to allow the connection. This ensures that connections are not blocked unnoticed.
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Should access be allowed?
 If this box appears, you have a few options. You can click "Allow access" and allow inbound connections through the firewall. You can also click "Cancel" and the firewall will still block incoming connections for this application.
You can also choose in which network types the connections should be allowed. For example, you can allow a media server application only on private networks. That way nobody can connect to your media server when you connect your laptop to public Wi-Fi. However, people on your home or work network can still connect.
When you connect to a network, you can choose whether it's public or private. Windows does not recognize this automatically. You can change this option for a network later in Control Panel or in the Settings application.
If you trust an application and want to use all its features, you should allow access. If you do not allow access to a PC game, you may not be able to host multiplayer games. If you see this prompt and you want to use a media server to share your media with other systems on your network, you'll probably need to allow access. For example, a BitTorrent client requires this access to upload data to other systems on the Internet.
If you do not allow access, an application may not work properly. Therefore, you may not be able to host multiplayer games in a PC game because the firewall is blocking inbound connections.
If you do not recognize the application, you might want to search for the name on the web and search for more information. Some types of malware act as servers and may trigger a firewall alert. Scan your favorite antivirus program if you think your PC contains malware.
RELATED: What is the difference between private and public networks in Windows?
Allowing or Disabling Later Access
The Windows Firewall does not ask you twice for the same application, but you can change the setting to allow or deny all applications in the future. Go to Control Panel> System and Security> Windows Defender Firewall> Allow an app or feature through the Windows Defender firewall.
Click "Change Settings" to unlock the settings. Locate the application in the list and select the "Public" or "Private" check boxes to control whether it is allowed or disallowed. If you uncheck both boxes next to an application, you will not be able to connect to public or private networks. If you select both check boxes, the app can connect to both.
If you do not want to see these notifications, and Windows can automatically block incoming connections to all applications, you can.
Go to Control Panel> System and Security> Windows Defender Firewall> Change notification settings.
To disable notifications, clear the Notify Me check box if the Windows Defender firewall is blocking a new app. There are two options here: one for private networks and one for public.
This window is quite common on Windows, and you usually have an idea of why an application wants to use this level of network access. If you trust an app, in most cases it's safe to allow it. Even if you allow an application through Windows Firewall, the Network Address Translation (NAT) feature of your router prevents many incoming connections unless you set up port forwarding.