ngrep is one alternative to tcpdump:
$ sudo ngrep -q -d lo0 -W byline host localhost and dst port 3002
The command will listen to interface lo0 and print all traffic destined for localhost port 3002.
Write traffic on port 80 (HTTP) to a file. Rotate log file after 10Mb. Keep 5 files.
$ sudo tcpdump port 80 -n -i any -w /tmp/traffic -p -C 10 -W 5 -s 1500
On OSX remember to install tcpdump with brew:
$ brew install tcpdump