这是我无意中攻击一个网站发现的一个代码PHP有效的拦截住我的DDOS 

<?php  

//查询禁止IP  

$ip =$_SERVER['REMOTE_ADDR'];  

$fileht=".htaccess2";  

if(!file_exists($fileht))file_put_contents($fileht,"");  

$filehtarr=@file($fileht);  

if(in_array($ip."\r\n",$filehtarr))die("Warning:"."<br>"."Your IP address are forbided by some reason, IF you have any question Pls emill to shop@mydalle.com!");  

//加入禁止IP  

$time=time();  

$fileforbid="log/forbidchk.dat";  

if(file_exists($fileforbid))  

{ if($time-filemtime($fileforbid)>60)unlink($fileforbid);  

else{  

$fileforbidarr=@file($fileforbid);  

if($ip==substr($fileforbidarr[0],0,strlen($ip)))  

{  

if($time-substr($fileforbidarr[1],0,strlen($time))>600)unlink($fileforbid);  

elseif($fileforbidarr[2]>600){file_put_contents($fileht,$ip."\r\n",FILE_APPEND);unlink($fileforbid);}  

else{$fileforbidarr[2]++;file_put_contents($fileforbid,$fileforbidarr);}  

}  

}  

}  

//防刷新  

$str="";  

$file="log/ipdate.dat";  

if(!file_exists("log")&&!is_dir("log"))mkdir("log",0777);  

if(!file_exists($file))file_put_contents($file,"");  

$allowTime = 120;//防刷新时间  

$allowNum=10;//防刷新次数  

$uri=$_SERVER['REQUEST_URI'];  

$checkip=md5($ip);  

$checkuri=md5($uri);  

$yesno=true;  

$ipdate=@file($file);  

foreach($ipdate as $k=>$v)  

{ $iptem=substr($v,0,32);  

$uritem=substr($v,32,32);  

$timetem=substr($v,64,10);  

$numtem=substr($v,74);  

if($time-$timetem<$allowTime){  

if($iptem!=$checkip)$str.=$v;  

else{  

$yesno=false;  

if($uritem!=$checkuri)$str.=$iptem.$checkuri.$time."1\r\n";  

elseif($numtem<$allowNum)$str.=$iptem.$uritem.$timetem.($numtem+1)."\r\n";  

else  

{  

if(!file_exists($fileforbid)){$addforbidarr=array($ip."\r\n",time()."\r\n",1);file_put_contents($fileforbid,$addforbidarr);}  

file_put_contents("log/forbided_ip.log",$ip."--".date("Y-m-d H:i:s",time())."--".$uri."\r\n",FILE_APPEND);  

$timepass=$timetem+$allowTime-$time;  

die("Warning:"."<br>"."Sorry,you are forbided by refreshing frequently too much, Pls wait for ".$timepass." seconds to continue!");  

}  

}  

}  

}  

if($yesno) $str.=$checkip.$checkuri.$time."1\r\n";  

file_put_contents($file,$str);  

?>