Making a simple packet analyser program

[Simon]

Hi everyone,

I'd quite like to create a small application that could listen on a
port and take a copy of any communications going in or out.
The end goal is to be able to offer statistics and stuff regarding the
packets, and also to join them up and allow for easy reading of the
packets and headers etc.

The question is, how is it done?

I know how to communicate across a port but I'm thinking, if the port
is already open then the program wouldnt work. Is there any way I can
listen in on the communications and take a copy.

Many thanks to anyone who can share their wisdom!

Thanks
Simon

 

[Daniel O'Connell]

This is about all I can offer, I don't know much else but this might help
http://www.codeproject.com/dotnet/dotnetwinpcap.asp

 

[William Stacey]

http://www.c-sharpcorner.com/Network/SimpleSnifferInCSLM.asp is interesting.
He also shows a novel way to parse the byte array into a struct using unsafe
code that solved a problem for me before.

 

[styko]

If you want to capture whole packets including for example ethernet header
you will have to use low level packet capturing library. The most famous is
WinPCAP (winpcap.polito.it)