WinpkFilter Description:

WinpkFilter is the development framework for designing low-level network applications. With WinpkFilter you can implement custom firewall, internet connection sharing (NAT), IP shaper, VPN and many other low-level network solutions completely in user-mode using your favorite development environment: Visual C++, Delphi, C++ Builder and etc. WinpkFilter does not require you to be experienced in kernel mode programming; it provides you with powerful user level API instead. However, if you need to implement your solution (because of performance issues) in kernel then to your satisfaction raw IOCTL interface is also available.