Now this isn’t the most accurate method out there but it is by far the easiest.

Open up your console and type
 netstat -an | grep :443 | grep ESTABLISHED | wc -l


or even better, for a running total

watch "netstat -an | grep :443 | grep ESTABLISHED | wc -l"


Just to add one more not without getting too technical

netstat -an | grep :443 | grep -v TIME_WAIT | wc -l

should give you all connections that the local server hasn’t closed, depening on your application, this may be more accurate