php防止ddos攻击实例代码，如下所示：

<?php //查询禁止IP $ip =$_SERVER[&#39;REMOTE_ADDR&#39;]; $fileht=".htaccess2"; if(!file_exists($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[&#39;REQUEST_URI&#39;]; $checkip=md5($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); ?>