该代码是利用百度的五秒盾的原理，用php模拟百度云加速防cc写了一个简单的防护

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<?php
define('SYSTEM_ROOT', dirname(preg_replace('@\\(.*\\(.*$@', '', preg_replace('@\\(.*\\(.*$@', '', __FILE__))) . '/');
session_start();
date_default_timezone_set('Asia/Shanghai');
header('Content-Type: text/html; charset=UTF-8');
function getspider($useragent=''){
    if(CC_Defender==2)return false;
    if(!$useragent){$useragent = $_SERVER['HTTP_USER_AGENT'];}
    $useragent=strtolower($useragent);
    if (strpos($useragent, 'baiduspider') !== false){return 'baiduspider';}
    if (strpos($useragent, 'googlebot') !== false){return 'googlebot';}
    if (strpos($useragent, 'soso') !== false){return 'soso';}
    if (strpos($useragent, 'bing') !== false){return 'bing';}
    if (strpos($useragent, 'yahoo') !== false){return 'yahoo';}
    if (strpos($useragent, 'sohu-search') !== false){return 'Sohubot';}
    if (strpos($useragent, 'sogou') !== false){return 'sogou';}
    if (strpos($useragent, 'youdaobot') !== false){return 'YoudaoBot';}
    if (strpos($useragent, 'yodaobot') !== false){return 'YodaoBot';}
    if (strpos($useragent, 'robozilla') !== false){return 'Robozilla';}
    if (strpos($useragent, 'msnbot') !== false){return 'msnbot';}
    if (strpos($useragent, 'lycos') !== false){return 'Lycos';}
    if (strpos($useragent, 'ia_archiver') !== false || strpos($useragent, 'iaarchiver') !== false){return 'alexa';}
    if (strpos($useragent, 'archive.org_bot') !== false){return 'Archive';} 
    if (strpos($useragent, 'robozilla') !== false){return 'Robozilla';} 
    if (strpos($useragent, 'sitebot') !== false){return 'SiteBot';} 
    if (strpos($useragent, 'mj12bot') !== false){return 'MJ12bot';} 
    if (strpos($useragent, 'gosospider') !== false){return 'gosospider';} 
    if (strpos($useragent, 'gigabot') !== false){return 'Gigabot';} 
    if (strpos($useragent, 'yrspider') !== false){return 'YRSpider';} 
    if (strpos($useragent, 'gigabot') !== false){return 'Gigabot';} 
    if (strpos($useragent, 'jikespider') !== false){return 'jikespider';} 
    if (strpos($useragent, 'addsugarspiderbot') !== false){return 'AddSugarSpiderBot';} 
    if (strpos($useragent, 'testspider') !== false){return 'TestSpider';} 
    if (strpos($useragent, 'etaospider') !== false){return 'EtaoSpider';} 
    if (strpos($useragent, 'wangidspider') !== false){return 'WangIDSpider';} 
    if (strpos($useragent, 'foxspider') !== false){return 'FoxSpider';} 
    if (strpos($useragent, 'docomo') !== false){return 'DoCoMo';} 
    if (strpos($useragent, 'yandexbot') !== false){return 'YandexBot';} 
    if (strpos($useragent, 'ezooms') !== false){return 'Ezooms';/*个人*/} 
    if (strpos($useragent, 'sinaweibobot') !== false){return 'SinaWeiboBot';} 
    if (strpos($useragent, 'catchbot') !== false){return 'CatchBot';} 
    if (strpos($useragent, 'surveybot') !== false){return 'SurveyBot';} 
    if (strpos($useragent, 'dotbot') !== false){return 'DotBot';} 
    if (strpos($useragent, 'purebot') !== false){return 'Purebot';} 
    if (strpos($useragent, 'ccbot') !== false){return 'CCBot';} 
    if (strpos($useragent, 'mlbot') !== false){return 'MLBot';} 
    if (strpos($useragent, 'adsbot-google') !== false){return 'AdsBot-Google';}
    if (strpos($useragent, 'ahrefsbot') !== false){return 'AhrefsBot';}
    if (strpos($useragent, 'spbot') !== false){return 'spbot';}
    if (strpos($useragent, 'augustbot') !== false){return 'AugustBot';}
    return false;
}
if($_GET['rand'] && $_SESSION['rand_session']!=$_GET['rand']){
    @header('Content-Type: text/html; charset=UTF-8');
exit('<b>浏览器不支持COOKIE或者不正常访问！</b>');
}
if(!$_SESSION['rand_session'] && $nosecu!=true){
    if(!getspider()){
        $rand_session=md5(uniqid().rand(1,1000));
    $_SESSION['rand_session']=$rand_session;
        exit("<!DOCTYPE HTML>
<html>
<head>
<meta charset=\"UTF-8\"/>
<meta name=\"viewport\" content=\"width=device-width, initial-scale=1, maximum-scale=1\" />
<title>安全检查中...</title>
<script> var i = 5; 
var intervalid; 
intervalid = setInterval(\"fun()\", 1000); 
function fun() { 
if (i == 0) { 
window.location.href = \"?{$_SERVER['QUERY_STRING']}&rand={$rand_session}\"; 
clearInterval(intervalid); 
} 
document.getElementById(\"mes\").innerHTML = i; 
i--; 
} 
</script> 
<style>
html, body {width: 100%; height: 100%; margin: 0; padding: 0;}
body {background-color: #ffffff; font-family: Helvetica, Arial, sans-serif; font-size: 100%;}
h1 {font-size: 1.5em; color: #404040; text-align: center;}
p {font-size: 1em; color: #404040; text-align: center; margin: 10px 0 0 0;}
#spinner {margin: 0 auto 30px auto; display: block;}
.attribution {margin-top: 20px;}
</style>
</head>
<body>
<table width=\"100%\" height=\"100%\" cellpadding=\"20\">
<tr>
<td align=\"center\" valign=\"middle\">
<noscript><h2>请打开浏览器的javascript，然后刷新浏览器</h2></noscript>
<h1><span data-translate=\"checking_browser\">浏览器安全检查中...</span></h1>
<p data-translate=\"process_is_automatic\"></p>
<p data-translate=\"allow_5_secs\">还剩 <span id=\"mes\">5</span> 秒</p>
</div></div></td></tr></table></body></html>");}}
?>

将以上php代码写进网站头部的php文件即可，这样一来，只有经过检测得到cookie的浏览器才能正常的访问你的网站了，当然了，面对数十万的CC攻击，这代码还是无能为力的。