<?php

/**

 * @author Bettina Schwarzer, Fritz-Haber-Institut

 * @copyright 01/2014

 */

function isintern($ip)

{

        if (!preg_match("/^141\.14\./", $ip) &&

            !preg_match("/^172\.(1[6-9]|2[0-9]|31)\./", $ip) &&

            !preg_match("/^10\.0\./", $ip)) {

                echo "extern: ".$ip. "<br />";

                return false;

        }

        else 

        {

            echo "intern: ".$ip. "<br />";

            return false;

        }

}

isintern($_SERVER["REMOTE_ADDR"]);

echo ", ".ip2long($_SERVER["REMOTE_ADDR"]);

echo "<br /><br />";

foreach(array('171.15.255.555',

              '172.16.0.0', 

              '172.24.3.3', 

              '172.16.3.3',

              '172.18.3.3',

              '172.24.3.3',

              '172.31.255.255',

              '172.32.0.0',

              '10.0.1.128',

              '123.123.123.123',

              '8.8.8.8',

              '141.14.127.255',

              '141.14.128.0',

              '141.14.143.255',

              '141.14.144.0',

              '141.14.141.141') as $ip) { 

                isintern($ip);

                }

echo "<br /><br />";

function islocal($ip) {

  foreach(array('172.16.0.0/12', '141.14.128.0/20','10.0.0.0/8') as $net) {

    list($subnet, $mask) = explode('/', $net);

    if ((ip2long($ip) & ~((1 << (32 - $mask)) - 1) ) == ip2long($subnet)) return true;

  }

  return false;

}

foreach(array('171.15.255.555',

              '172.16.0.0', 

              '172.24.3.3', 

              '172.16.3.3',

              '172.18.3.3',

              '172.24.3.3',

              '172.31.255.255',

              '172.32.0.0',

              '10.0.1.128',

              '123.123.123.123',

              '8.8.8.8',

              '141.14.127.255',

              '141.14.128.0',

              '141.14.143.255',

              '141.14.144.0',

              '141.14.141.141') as $ip) {

  if (islocal($ip)) echo "$ip local<br>\n";

  else echo "$ip extern<br>\n";

}

?>