Firewall project is not loaded in Visual Studio 2015 since the Firewall Project file(.vcxproj) is missing. Following steps can be used to load firewall project in Visual Studio:
1. Download Firewall.vcxproj file attached in this article.
2. Place it in the Firewall directory in <NetSim Install Directory>/src/Simulation/ folder.
3. Close Visual Studio if it is already open.
4. Open NetSim.sln file in <NetSim Install Directory>/src/ folder in Visual Studio 2015.
You will now be able to find firewall.c and Firewall.h files under the Firewall project in the solution explorer.