The TCPMapping filter API lets you intercept TCP connections and data travelling from a client to a server through a TCP mapping service. You can modify the data, make additional connections and send data to the server or client side. Whilst other filters are high-level protocol specific (HTTP, POP3), TCP mapping filters monitor at the TCP level allowing more fine grained control.

Below is an example of 3 TCP mapping filters in the filter chain

In order to monitor TCP connections there must be a TCP Mapping service running in WinGate as this service is the one that accepts registration of the filters and pushes events to them.

Protocols

Because the TCP mapping filter framework sits at the TCP level, it is effectively protocol agnostic. Therefore when you write a TCP mapping filter you need to ensure that you either handle data of any protocol, or inform the user that they need to attach your filter only to the TCP mapping server that is dealing with protocol data that you can process.