function getIPaddress(){

        $IPaddress='';

        if (isset($_SERVER)){

            if (isset($_SERVER["HTTP_X_FORWARDED_FOR"])){

                $IPaddress = $_SERVER["HTTP_X_FORWARDED_FOR"];

            } else if (isset($_SERVER["HTTP_CLIENT_IP"])) {

                $IPaddress = $_SERVER["HTTP_CLIENT_IP"];

            } else {

                $IPaddress = $_SERVER["REMOTE_ADDR"];

            }

        } else {

            if (getenv("HTTP_X_FORWARDED_FOR")){

                $IPaddress = getenv("HTTP_X_FORWARDED_FOR");

            } else if (getenv("HTTP_CLIENT_IP")) {

                $IPaddress = getenv("HTTP_CLIENT_IP");

            } else {

                $IPaddress = getenv("REMOTE_ADDR");

            }

        }

        return $IPaddress;

    }

使用直接

echo getIPaddress();