<?php
function checkProxy($ip){
        $ip=$_SERVER['REMOTE_ADDR'];
        global $ip;
        $contactEmail="[email protected]"; //you must change this to your own email address
        $timeout=5; //by default, wait no longer than 5 secs for a response
        $banOnProability=0.99; //if getIPIntel returns a value higher than this, function returns true, set to 0.99 by default

        //init and set cURL options
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_TIMEOUT, $timeout);
        //if you're using custom flags (like flags=m), change the URL below
        curl_setopt($ch, CURLOPT_URL, "http://check.getipintel.net/check.php?ip=$ip&contact=$contactEmail");
        $response=curl_exec($ch);

        curl_close($ch);


        if ($response > $banOnProability) {
                return true;
        } else {
            if ($response < 0 || strcmp($response, "") == 0 ) {
                //The server returned an error, you might want to do something
                //like write to a log file or email yourself
                //This could be true due to an invalid input or you've exceeded
                //the number of allowed queries. Figure out why this is happening
                //because you aren't protected by the system anymore
                //Leaving this section blank is dangerous because you assume
                //that you're still protected, which is incorrect
                //and you might think GetIPIntel isn't accurate anymore
                //which is also incorrect.
                //failure to implement error handling is bad for the both of us
            }
                return false;
        }
}
$ip=$_SERVER['REMOTE_ADDR'];
if (checkProxy($ip)) {
    /* A proxy has been detected based on your criteria
     * Do whatever you want to here
     */
    echo "[403 Forbidden Error] - Access Denied<br />";
}
?>