How can I open a specific port on OS X 10.11.13 I am currently working with msfvenom on OS X. But I wanted to know, the terminal commands to open a specific port say for example 4444. Can someone please help me out with this?
You can use the terminal command nc -l 4444 to create a server that listens on port 4444.  However, I think your question really is about opening a port on your router.  If someone else out on the internet somewhere is trying to connect to you on port 4444, the router you have acts as a boundary between you and them, and most often all incoming ports by default are closed.  So even if you run a server on your Mac and it's listening on port 4444, traffic on that port needs to be allowed through at the router level.

Please give us more info so we can help you.