IP ban and check for fake IPs

gistfile1.php

<?php 
 /* This won't work on Tor services */
        function checkSecurity(){
             $list = "ban.txt";  
             $deny = array();  
             $fo = fopen($list, "r");  
             $str = fread($fo, filesize($list));  
             fclose($fo);  
             $str = str_replace(",","_",$str);  
             $ary = explode("_",$str);  
             for($i=0; $i < count($ary); $i++)  
             {  
                $deny[] = $ary[$i];  
             }  
             if(!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){ 
              $_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_X_FORWARDED_FOR']; 
             } 
             foreach($deny as $ip) { 
                if(eregi($ip,$_SERVER['REMOTE_ADDR'])) { 
                   die("## your ip banned!"); 
                } 
              } 
             if(!empty($_SERVER['HTTP_X_FORWARDED_FOR'])){ 
             banIP($_SERVER['HTTP_X_FORWARDED_FOR'],0); 
             } 
        } 
        function banIP($ip,$mode){ 
             $list = "ban.txt"; 
             if($_SERVER['HTTP_X_FORWARDED_FOR']) $ip = $_SERVER['HTTP_X_FORWARDED_FOR']; 
             $ip = explode(".",$ip); 
             $ip = $ip[0].".".$ip[1].".".$ip[2].".*"; // block the C-class 
             $fo = fopen($list, "a"); 
             fwrite($fo, $ip. ","); 
             fclose($fo); 
             die("## hacking detected :)"); 
        } 
        // detect
        checkSecurity(); 
 
        //banIP($_SERVER['REMOTE_ADDR']); - trigger to ban the IP
?>