A simple IP filter for detecting robots by IP address range.

IPControl.php

<?php
class IPControl {
  public static $ROBOT_IP_RANGES = array(
    array(
    'name'=>'Monitoring Server',
    'min'=>'173.203.5.0',
    'max'=>'173.203.5.127',
    ),
    array(
    'name'=>'Search Server',
    'min'=>'173.203.5.192',
    'max'=>'173.203.5.255',
    ),
  );


  public static function isKnownRobot($clientIP = null) {
    try{
      if(!$clientIP){
        $clientIP = $_SERVER['REMOTE_ADDR'];
      }

      foreach(IPControl::$ROBOT_IP_RANGES as $ipRange){
        $startRange = ip2long($ipRange['min']); 
        $endRange = ip2long($ipRange['max']); 
        $userIP = ip2long($clientIP);

        if ( $userIP >= $startRange && $userIP <= $endRange) {
          return true;
        } 
      }
      return false;
    }
    catch(Exception $e){
      return false;
    }
  }
}