Where to start when analyzing unknown network protocols

Apologies for the vagueness of the question here but can someone point me to some decent resources for learning how to capture a network stream and analyse the unknown protocol? I am trying to capture the stream from the live Formula1.com timing server on port 4321 so I can analyse it. The stream is totally unknown (i.e. I have no idea what information it contains etc) so I really 开发者_如何学Gohave no idea about where to start with reverse engineering it.

I am aware that there are some linux apps already available to do this but I want to make m own version, both as an exercise and so I can ensure that I can keep up to date in case the protocol changes as a lot of these codebases do not seem to be maintained that regularly.

From looking at the linux f1 timing app, it seems that the stream is a binary stream and you need to ping the server to get any sort of data from it. Would the suggestion be to use wireshark or some other sort of network analyzer and if so, one I perform a capture, how would I go about decoding/starting-to-make-sense-of the bitstream?

You can start by using a network protocol analyser such as wireshark. You can then configure wireshark to only show the data of a certain port (and or address) As you get all of this traffic you see what your computer says and what the server responds. From that you can easily reconstruct the Data stream if you do several connections all with other input data. (unless the stream is encrypted,, then it gets a lot more complex).

I hope this helps

The best way is to analyse it with tool like wireshark and then to post here the next questions.