proxy_pass

server {
    listen 80;
    server_name abc.com www.abc.com;
    location / {
    proxy_pass http://111.111.111.111;
    #proxy_redirect off;
    proxy_set_header Host $host;
    #proxy_set_header X-Real-IP $remote_addr;
    #proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
    }
}

// gnu common.php
if ($_SERVER['HTTP_X_FORWARDED_FOR'])
    $_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_X_FORWARDED_FOR'];