Based on my understanding, nginx is listening to already running services on the server. For example:
If you have a apache server and nginx server on the same machine,
apache server is your backend web server and
nginx is your front end
then you can start apache vhosts on different ports and nginx will route the 443 or 80 traffic to the appropriate apache vhosts based on server_name and proxy_pass configuration to different apache virtual SSL ports.
Please correct me if I am wrong.
If you have a apache server and nginx server on the same machine,
apache server is your backend web server and
nginx is your front end
then you can start apache vhosts on different ports and nginx will route the 443 or 80 traffic to the appropriate apache vhosts based on server_name and proxy_pass configuration to different apache virtual SSL ports.
Please correct me if I am wrong.