Allow port arbitrary port (such as 5432) open on El Capitan. I'm running vagrant and successfully port forwarding from there. My issue is that some ports are not running. I know vagrant is working because I can successfully forward port 80, but cannot forward 5432. 

Per these direction, I cannot sudo ipfw list as ipfw is not found on this OS (El Capitan thing I suppose?). 

stuff$ sudo ipfw list
sudo: ipfw: command not found


I'm running a GUI that is unable to connect to 5432, so I think it's on mac's end.
The ipfw firewall has been replaced by pf in Mac OS X Lion and later. Try looking at the man page for pfctl to start.

An old, but still good cheat sheet for pf

As for debugging network connections on the Mac, I would run netstat to see what ports had listeners. And possibly sudo lsof -i to see which process had which port open.