Way to Track Data through Port Numbers?

Is there a way to track data going through my network and specifically what port numbers it's going through?

I currently have users connecting to an old Airport Express which is connected to an AEBS and that to the modem. My guess on how this could work is if I connected my MBP to my AEBS wirelessly, then connect the Airport Extreme via Ethernet to my MBP, then share my internet connection to the AE, I can trace traffic coming from the users. Question is, is there a software that's in OSX or that I could download that would let me track and monitor this data and the ports it's going through?