Often there are situations in which this or that program connects to the network at startup. And if anti-virus utilities fully justify such arbitrariness by checking the relevance of virus databases and signatures and thereby ensuring security, then PC owners actively have to deal with some applications. This may be due to the non-disabled check for updates, the appearance of advertising banners inside the program, or a decrease in the speed of the computer. Users have the ability to prevent the program from accessing the Internet using both the built-in tools of the operating system and third-party applications.
Standard Windows tools
The most common operating system allows you to block applications from network access in many ways. Check them out below.
Windows Firewall

The most common, easiest and most convenient way is to use Windows Firewall. You can start its configuration from the "System and Security" section, which is located in"Control Panels". In the upper left corner, click on the "Advanced Options" link. In a new window, you need to open the "Rules for outgoing connection" tab, which will display a list of available rules for all Windows services. Here, already in the upper right part of the screen, there is the "Create rule" item, by clicking on which you can select what exactly it is created for. You should select the top line "Programs", click "Next", and then select the path to the application executable file. In the next window, the "Block connection" item is checked by default, it must be left unchanged, then a profile is selected (here it is better to leave everything active), in the final, the user will be asked to give the rule a name and a short description as a hint. The "Finish" button completes the setting. A line with a new rule will appear at the beginning of the list, which will prohibit the program from accessing the Internet.
The same should be done with advertisements for applications that require an Internet connection to work. In this case, not the entire program is entered into the rule, but only the IP address to which it accesses. And this address, of course, is not advertised. Therefore, the Resource Monitor utility integrated into the Windows Task Manager comes to the rescue, allowing you to track the network activity of a specific program at specific addresses. It looks like this.

In the settings of the new rule, you should check not "Programs", butitem "Custom", and on the tab on the left, select "Protocols and ports". In the next window, you need to drive the clarified IP into the field of remote IP addresses, and then complete the setup in the same way.
IP Security Policies
Initially, it may seem that the method is incredibly complicated and to prevent the program from accessing the Internet, as a rule, many users cannot, seeing countless opening menus and obscure terms. Despite the fact that the method is intended specifically for experienced users or technical specialists, it will not be difficult for an ordinary person to understand this policy. With this function, you can block the program from accessing the Internet, either completely or partially.

The security rules wizard is located in the "Administration" section. After launch, an empty window is displayed, right-click on which you need to select "Create an IP security policy". Further actions do not require any technical skills, since the system will use the "Security Policy Wizard", which will guide the user through all the menus and windows that open. All default values do not need to be changed, since certain actions that can cause complexity will need to be performed only at the stage of creating IP filters:
- "IP traffic source" - check "My IP address" here.
- "IP traffic assignment" - select "Specific IP address or subnet".
- Enter the IP found by "Resource Monitor" into the form.
- Select protocol type - set to "Any".
- End the Wizard.

The next step is the actual blocking. It is performed by selecting the newly created filter and creating a "Filter Action" rule, where you need to select the "Block" item. After completing this step, the previously created policy will be displayed in a previously empty window. You need to call its context menu and select "Assign" in it, after which it will take effect.
How to disable Internet access with third-party utilities?
Users have a wide variety of security utilities at their disposal, with more options than Windows Firewall. Some of them are part of antivirus products, some are separate applications. PC owners choose products from different manufacturers: Kaspersky, Dr. Web, AVG, Comodo, McAffee, etc., but they all have similar functionality and, most importantly, a convenient and simple interface, thanks to which the user can easily both deny the program access to the Internet and configure many other security settings.