Windows - How to stop app from getting list of running apps on local area network?

Question

I have an application, which can somehow detect, If the same app si already running on other computer connected to local area network.

I would like to block it from checking running apps on other computers.

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What I have tried so far:

First: I have tried to disable local area network connection at all - it worked, application was unable to do the check, but internet connection was disabled too.

Second: I have tried to block Internet access for that specific app (EXE) in Windows Firewall. Sadly - this didn't work, app is still able to detect already running processes of the same app on other computers.

Third: I have navigated to Network setting -> Advanced sharing settings and blocked all sharing options on both computers. That didn't help.

Fourth: I have tried to block Windows Management Instrumentation service (WMI) - just in case that app is using it to detect applications on network PC.

Fifth: I have blocked all other EXEs in Windows firewall in the program folder from internet access - didn't work.

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Next idea could be: somehow detect process activity when application starts and watch, what services are being called to detect running apps on local area network. Maybe monitor network activity too?

My last idea is: run that application on virtual machine without internet access, so this check will not be done + I will still have an internet access.

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Windows 10

Answer 1

The app probably does not detect other running instances on the network via the Internet. Rather, the app probably just communicates over the network. This would explain why your First method worked and Second didn't.

Make sure that you block all network connections, not just connections to the Internet.

You can use tcpview or Process Explorer to verify that this is the case. Here's a screenshot from Process Monitor:

These tools will also tell you the network port(s) used by the application to communicate. You can then add a further rule to the firewall to block all inbound connections on the port that the application uses to communicate.