Windows Firewall enables you to block all outgoing connections to restrict applications from connecting to the internet. Here's how.

Windows has a default firewall application that gives you granular control over the web access as well as allows you to configure all of the incoming and outgoing connections. By default, the Windows firewall is configured to allow all outgoing connections unless they're blacklisted and block all incoming connections unless they're whitelisted.

Most Windows programs have almost unrestricted access to outgoing connections. Which means that the applications can phone home and perform other pursuits with no restrictions.

If you do not like this behavior then you can use the Windows Firewall choices to block all outgoing connections. Blocking oubound connections is useful when you want granular control over which applications can send data on the internet.

The method shown below is verified to work with Windows 10, 8, & 7. Before making any changes, I strongly recommend you to definitely backup Windows Firewall settings.

Steps to bar All Outgoing Connections with Windows Firewall

These are the steps you need to follow to bar outgoing connections in Windows Firewall.

Open the Start menu.

Search for "Windows Defender Firewall" and open it.

Click the "Advanced Settings" link within the Firewall application.

Here, choose the "Windows Defender Firewall with Advanced Security on Local Computer" option on the left panel.

Click on the "Windows Defender Firewall Properties" link in the middle panel.

Within the Firewall properties window, go to the profile tab of your choice.

Domain profile tab: When the product is joined inside a domain.
Private profile tab: If the product is connected to a private network (like home or office network).
Public profile tab: When the product is linked to a public network (like a coffee shop WiFi)

With my case, I'm selecting the Private profile tab because I'm connected to a private network. For any vast majority of users, this is actually the choice to select.

Here, select "Block" in the drop-down menu alongside "Outbound connections".

Click around the "Apply" and "Ok" buttons in order to save changes.

Close Windows Firewall application.

The changes are instant. In the future, all outbound connections are blocked and applications cannot send any data over the network.

Whitelist Applications to permit Outbound Connections

To permit outgoing connections for specific applications, you need to manually whitelist them. Whitelisted application takes priority within the general block rule for outbound connections. For instance, you may want the Chrome browser to work even if you blocked the outbound connections.

Adopt these measures to whitelist applications for outbound connections.

Open Windows Firewall.
Click around the "Advanced Settings" link.
Select "Outbound rules" around the left panel.
Click the "New rule" option within the right panel.
Select "Program" and click on "Next".
Select "This program path" and click on "Browse".
Discover the application's exe file, select it, and click on the "Open" button.
Click "Next".
Select "Allow this connection" and click "Next".
Select Domain, Private, and Public checkboxes and click "Next".
Name the rule and click on "Finish".

Once you click on the Finish button, the outbound rule will be created and put on the firewall. From now, the whitelisted application will be able to send data within the network whether or not the outbound connections are blocked.

FIXED: Some Applications can Still Connect with the Internet After Blocking Outgoing Connections

Despite block all outbound connections, some applications can continue to send data within the network. For instance, most built-in Windows applications and services can send data within the network. It is because those applications are whitelisted by the system.

If you don't want those applications accessing the outgoing connections, you need to manually disable the outbound rule for those applications within the Firewall settings. Allow me to demonstrate how.

Open the Windows Firewall application.
Around the left panel, click on the "Advanced Settings" link.
Here, choose the "Outbound Rules" option around the left panel.
In the centre panel, find the rule related to the application you want to block.
For instance, I want to block the Windows 10 Email app. So, I decided it.
Right-click on the rule and choose the "Disable Rule" option.

That is it. The changes are instant. For demonstration purposes, I additionally blocked the outbound rule for the legacy Edge browser. As you can see in the image below, it can't connect with the web because of the restriction of the outgoing rule. Do this to any or all the applications you wouldn't want connecting to the internet.