NetFilter SDK is a framework for transparent filtering the data packets transmitted via network. It suits for developing the content filters, basic application level firewalls, traffic analyzers/shapers, other software that requires viewing and modifying TCP traffic, and control access for UDP.
The solution allows filtering outgoing TCP connections and allow/block UDP datagrams in user mode application. It is possible to filter the specified subset of connections/datagrams, restricted by filtering rules. The outgoing TCP connections can be redirected to different address.
The filtering driver operates on transport level, on the top of TCP/IP stack. In effect it automatically supports all kinds of TCP/IP capable network adapters: Ethernet, Dial-up/DSL/Cable modems, wireless adapters including Wi-Fi and Bluetooth, virtual adapters like loopback or VPN.
The process context (as process identifier) is available for TCP network activity.
The API is easy in use, but powerful.