<?php

//------ Phan can chinh sua ---------------

$level = 1; //muc bao ve: 1:binh thuong; 2:cao

// Neu ban chon $level = 2 thi hay dien ten mien cua ban o phia sau:
$yoursite = "localhost"; //Nhap domain of ban,ko can http://www.


/* Ok, gio ban con 2 cai chon:
- dieu chinh on/off anti_ddos truc tiep tren file nay (1)
- dieu chinh on/off anti_ddos o 1 site trung gian (2)
*/

$scheme = 1; //Dien mot trong hai so: 1: chon cach thu (1) 2: Chon cach thu (2)

// Neu ban chon(1) thi hay edit phan nay:
$antidos = 1; //Nhap 1 de on, 0 de off anti ddos

// Neu ban chon(2) thi hay edit phan nay:
$determiner = "http://host-trung-gian.com/dieukhien.txt"; //Link toi file qui dinh on/off anti ddos - Neu ban muon bat anti ddos chi viec nhap noi dung file nay so "1"


//co the chinh sua phan sau,khong can de copyright,hoac de nguyen van dc.
$wwwect = "<br><br></p><br>
</p>
<br><br><center><b>Xin Vui Lòng<br><br><p><a href='".$_SERVER['REQUEST_URI']."'>>>>>>>>>>[ Click vào Đây ]<<<<<<<<<</a><br><br><p>để chuyển đến nội dung cần xem...!</b>
<br><br><br></p><br>
</p>
<br><br>
<br><br><br></p><br>
</p>
<br><br><br><br>
</p>
<i><u>Code by Unlockvn Team (c)Anti DDoS v1.0 Final - 2001 - 2006 Unlockvn Vietnam Group Services</u></i></center>";

// -------------- Het phan chinh sua- Ko chinh sua phan duoi!!! ------------


//###########################################################################################
// ### Code by UnlockVn Team (c) 2001 - 2006 UnlockVn Vietnam Group Services ###
//###########################################################################################

//Ok, lam may cai function da

function url_exists($url) {
$a_url = parse_url($url);
if (!isset($a_url['port'])) $a_url['port'] = 80;
$errno = 0;
$errstr = '';
$timeout = 30;
if(isset($a_url['host']) && $a_url['host']!=gethostbyname($a_url['host'])){
$fid = fsockopen($a_url['host'], $a_url['port'], $errno, $errstr, $timeout);
if (!$fid) return false;
$page = isset($a_url['path']) ?$a_url['path']:'';
$page .= isset($a_url['query'])?'?'.$a_url['query']:'';
fputs($fid, 'HEAD '.$page.' HTTP/1.0'."\r\n".'Host: '.$a_url['host']."\r\n\r\n");
$head = fread($fid, 4096);
fclose($fid);
return preg_match('#^HTTP/.*\s+[200|302]+\s#i', $head);
} else {
return false;
}
}


function on_off($file) {
$string = file_get_contents($file);
$fetch = strstr($string,"1");

if ($fetch) {
return true;
}

else {
return false;
}
}

function level_1() {
global $antidos, $wwwect;
if($antidos){
if(!$_SERVER['HTTP_REFERER']) {
echo $wwwect;
exit;
}
}
}

function level_2() {
global $antidos, $wwwect, $yoursite;
if($antidos){
if(strpos($_SERVER['HTTP_REFERER'], 'http://www.'.$yoursite) !== 0) {
if(strpos($_SERVER['HTTP_REFERER'], 'http://'.$yoursite) !== 0) {
echo $wwwect;
exit;
}
}
}
}
// Done here,met qua hehe.


if($scheme == 1) {
if($level == 1) level_1();
elseif($level == 2) level_2();
else { echo "Ban phai chon \$level = 1 hoac \$level = 2"; exit; }
}

elseif($scheme == 2) {
if (!url_exists($determiner)) $antidos = 1;
else { $antidos = on_off($determiner); }

if($level == 1) level_1();
elseif($level == 2) level_2();
else { echo "Ban phai chon \$level = 1 hoac \$level = 2"; exit; }
}

else {
echo "Ban phai chon \$scheme = 1 hoac \$scheme = 2";
exit;
}
//Ok, xong roi, don gian nhung hieu qua,
//nhung y kien dong gop cua cac ban co the lien he
//tai dien dan unlockvn.com de cung
//dua ra bien phap chong ddos hieu qua.thank' all, have fun...
?> 

to trairatngheo: cái này thật sự không phức tạp đâu, bạn chỉ cần chỉnh sửa cái
$yoursite = "localhost";
thay cái localhost thành tên web thôi. Hơn nữa, nếu dùng htaccess, khách fai viết tên + pass vào mệt lắm, và dùng htaccess có thể fake được