Overview

Port Spy is a port monitoring application that allows you to see exactly what is being transferred to and from a TCP/IP port.

The only thing you need is the capability to configure the port of either client or server to be able to insert Port Spy in between.

Port Spy 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. Data received from the client is transferred -unaltered- to the server, and data replied by the server is transferred -unaltered- to the client.

There is one caveat however: While Port Spy does not change the data itself, it may change the blocking of the data. That is the grouping of data into blocks of bytes. Since blocking is a dynamic aspect of TCP/IP over which applications have no control, the client & server will be subject to this phenomenon anyhow. Even without Port Spy blocking can be different in each session.

The blocks shown by Port Spy are the blocks as they are received from either client or server.

If you develop TCP/IP software, you need a utility like Port Spy.

And just in case you need a leg up on socket programming in Swift, Port Spy comes complete with source code. Yes you read that correctly: Port Spy includes Source Code. Select “File -> Export Source Code” to obtain the Xcode project that was used to create Port Spy with all sources and even the artwork.

So not only do you get a fully functional utility, you also get to see first hand just exactly how it was made.