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November 30, 2013

Network Detection System

by MordyT

MordyT proudly presents…. NetworkDetectAndDeter

What it is used for:

This program was designed to discourage users from pulling out the network cable on their PC.

What you need:

You need a copy of the Network Detector and a copy of BIS. These are 2 separate files that work together. Depending on your setup, you need a UAC version or a Admin Version. (Admin not yet available)

How it works:

Network Detector

There are 2 parts – A detection program and an action program.

The detection program (called ND.exe) is very simple.

  • Once a second, it checks the status of the network connection.
  • If it is found to be down, it calls the action program. Then it checks again.
  • If it is found to still be down, it checks if the action program is running and if not, calls it again.
  • If it is running, it goes back to the beginning.
  • When the network connection comes back up, it sends a terminate command to the action program, and then checks again.
  • If it is up, it simple goes back to the beginning.

Here is it’s logic in flowchart format:

This program (ND.exe) is very lightweight and uses less than 1% CPU.

Action Program

The action program can vary and does not need to the one I supply. You can use your own program, as long as it is named BIS.exe and is in the same directory as the detection program.

I do however supply an action program. This program is very powerful. It will block all mouse and keyboard input to the PC for as long as it is running, as well as black out the screen and display a helpful message.

There are a couple niggles with my supplied action program…

  1. It does not block Ctrl + Alt + Del. These buttons, plus Win+L still work. In the Ctrl + Alt + Del screen mouse and keyboard work as well. However, once you leave that screen, the blocking continues.
  2. Sometimes, you can get the taskbar to appear, however you cannot click on anything shown there. (FIXED in v1.1)

I know you all are going to wonder… UAC? Elevated rights? There are a few options in this case.

  1. The action program I supplied works with UAC and limited rights. However, it must be running in the users context – which in theory means they can terminate it.
  2. I do have a version that can run in an admin context – but that version requires admin rights. It is also far more powerful as it will freeze the mouse movement as well. It also uses more resources unfortunately. And Ctrl + Alt + Del cannot be blocked just like this version. More info and release of this soon.

How to set it up:

So what’s the recommended setup? A scheduled task, running a local copy of the ND program, at user login is what I recommend. Using that + blocking access to taskmgr through Software Restriction Policies (to prevent someone from closing the ND program) seems to do the trick.

Planned features:

What’s planned next?

  1. Finish the Admin Level blocking program.
  2. Running the ND program as Admin while running the client as non-admin.


I highly recommend you test this before deploying it.


I hope you find this program useful – please let me know if you do, don’t, have questions, feature requests, etc. Donations are also accepted and help me build better programs.


Last but not least… license / usage. You may use this program for personal or non-commercial use for free. You may not distribute this software without written permission from MordyT. You are allowed to distribute the client/admin to PC’s under your control. Commercial users please contact me for more details. You may not attempt to reverse engineer, modify, or change the program. Any questions are welcome.



v1.0 Network Detect: Initial Release
v1.0 BIS: Initial Release
v1.1 BIS: Added code to auto close Task Manager and to re-maximize the block screen as needed.

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