It is not recommended to implement a firewall-hook driver (or firewall driver) for Microsoft Windows XP and later versions of the operating system.

The Microsoft Windows 2000 DDK introduced the concept of a firewall-hook driver. The intent of a firewall-hook driver was to manage network packets that were sent and received across a firewall in the context of the TCP/IP protocol. A firewall is a control system that prevents unauthorized users from gaining access to a local network that is connected to the Internet.

A firewall-hook driver did not meet firewall requirements because it ran too high in the network stack. A firewall-hook driver could also interfere with the operations of Internet Connection Sharing (ICS) or a personal firewall implementation.

To provide firewall functionality on Windows XP and later, you should create an NDIS intermediate miniport driver to manage packets sent and received across a firewall. For information about creating an NDIS intermediate miniport driver, see NDIS Intermediate Drivers.