Port Spy is a port monitoring application that allows you to see exactly what is being transferred to and from a TCP/IP port. This app is a so-called “man-in-the-middle” observer. The client is no longer connected to the server, but to Port Spy. Port Spy connects itself to the server. The data received from the client is transferred - unaltered - to the server, and data replied by the server is transferred - unaltered - to the client.