title: nginx:which port send the request?
body: <p>I am using nginx as forward proxy. I want to record all the ports nginx is using. Now I know <code>$server_port</code> is the listened port. Nginx receives request from listened port, then creates a new connection and sends the request to <code>$upstream_addr</code>. How can I log the new connection's port to access.log?</p>