This is the link where you can found the app: https://sourceforge.net/projects/tcp-over-all-tunnels/ Basically this app listens on your localhost on a given port and modifies incoming tcp requests payload and acts like a tunnel. Could anyone provide me some insights on what is the underlying concepts in this app and how to create/code this kind of app using vb.net.
That rar file with the source code is damaged and can not be opened. You could try contacting the author and ask how the source code archive can be opened, since neither WinRAR nor 7-zip are able to open it. I wouldn't use VB or C# to do that. I'd use C++. I would make it a Windows service, since you need to a lot of low-level processing to directly modify TCP packets real-time. You could use a pair of VMs to test your code, but, IMHO networking is a little bit tricky in a VM. So use two machines and a router / switch if you have them. You'll need to generate TCP packets and send them to the other machine, so that it can perform the tunneling. So, You'll need to monitor packets and watch ports. This might prove useful. https://www.wireshark.org/ Good luck.