Wondering if a certain outbound port on your Mac is open or closed? Here’s a way to determine outbound open ports on Mac OS using netcat via the command line in terminal. We’ll use  using a free service from portquiz.net.

From the terminal, enter:

nc -v portquiz.net 443

where 443 is the port number you want to test.

Control-c will kill net cat after you get the info you want.

Easy-peasy. You can now determine outbound open ports on Mac OS.