ip_block_mu_plugin.php

<?php

function get_real_client_ip()

    {
       $ipaddress = '';
       if (isset($_SERVER['HTTP_CLIENT_IP']))
         $ipaddress = $_SERVER['HTTP_CLIENT_IP'];
       else if (isset($_SERVER['HTTP_X_FORWARDED_FOR']))
         $ipaddress = $_SERVER['HTTP_X_FORWARDED_FOR'];
       else if (isset($_SERVER['HTTP_X_FORWARDED']))
         $ipaddress = $_SERVER['HTTP_X_FORWARDED'];
       else if (isset($_SERVER['HTTP_FORWARDED_FOR']))
         $ipaddress = $_SERVER['HTTP_FORWARDED_FOR'];
       else if (isset($_SERVER['HTTP_FORWARDED']))
         $ipaddress = $_SERVER['HTTP_FORWARDED'];
       else if (isset($_SERVER['REMOTE_ADDR']))
         $ipaddress = $_SERVER['REMOTE_ADDR'];
       else
         $ipaddress = 'Unknown';
       return $ipaddress;
       }

$ips = array('127.0.0.1', '127.0.0.2');

if (!in_array( get_real_client_ip(), $ips)) wp_die('Smolík');