Your first statement is a bit ambiguous, but I have to ask if you've gotten tcpflow to work on OSX. I can never get it to output anything when trying to monitor connections to localhost.
If you're looking to monitor traffic to localhost, bind the the `lo0` interface. For example, when I'm monitoring traffic to a local Rails app in development, I'll do something along the lines of:
sudo tcpflow -c -n lo0 src or dst post 3000
and it'll pick up the traffic.
(Thanks for the tips on alternative ways of monitoring TCP traffic flows, folks!)
