Conseguir ip real del usuario

<?php

if ($_SERVER) {

     if ( $_SERVER[HTTP_X_FORWARDED_FOR] )
     {

          $realip = $_SERVER["HTTP_X_FORWARDED_FOR"];

      } elseif ( $_SERVER["HTTP_CLIENT_IP"] )
     {

          $realip = $_SERVER["HTTP_CLIENT_IP"];

      } else {

          $realip = $_SERVER["REMOTE_ADDR"];

      }

      } else {

          if ( getenv( 'HTTP_X_FORWARDED_FOR' ) ) {

                 $realip = getenv( 'HTTP_X_FORWARDED_FOR' );

          } elseif ( getenv( 'HTTP_CLIENT_IP' ) ) {

                 $realip = getenv( 'HTTP_CLIENT_IP' );

          } else {

                $realip = getenv( 'REMOTE_ADDR' );

          }

}

print("$realip");

?>