Closing an open port via Mac's terminal

Use below command in terminal to get a list of all open ports:

netstat -an | grep LISTEN

Find the process ID (PID) of the port you wish to close. You may need to use sudo.

lsof -i :[portNumber]

Then use the following command to kill the process listening on your port. You may need to use sudo with kill -9 parameter.

kill [PID]