When you do a reverse proxy in which Nginx will be the one who listen the traffic and forward anything needs to be process through PHP to Apache. With this, Apache will always receive an IP from Nginx server (or I should say localhost / 127.0.0.1 / local IP), not the real IP that user uses. In order to let Apache knows what is real user IP, we need to install mod_rpaf.
Just copy and paste code below into SSH :