PHP,.htaccess,DDoS和快速请求保护

<?php
#get the visitor ip
$ip = $_SERVER["REMOTE_ADDR"];

#start the session
@session_start();

#check if the ip is banned
if( $_SESSION['~b'] ){

#check if we can open htaccess
$fp = @fopen('./.htaccess','a'); 
    if($fp){
        #add the ip to htaccess
        @fwrite($fp,"rndeny from $ip"); 
        #close
        @fclose($fp);
        #destroy the session
        @session_destroy();
        @mail("my-email","IP Banned","Ip: $ip");
    }
    #let the user know why we deny him or her access
    die('To many requests.');
    }
#get the filename and location
$f = './log/'.@ip2long($ip);

#check if the file exists
if ( @is_file($f) ) {
        #get the last filetime
        $a = @filemtime($f);
        #touch the file,give a new filetime
        @touch($f,time());
        #the ip is not banned
        $_SESSION['~b']  = false;
        #add the time diff
        $_SESSION['~r'] += @time()-$a;
        #add the latest hit
        $_SESSION['~h'] += 1;
    }else{
        #create the file if it doesn't exist
        @file_put_contents($f,''); #size: 0kb
        #if touch() doesn't work
        #chmod($ipfile,0755); 
    }

#calculate the diff after 10 hits,and ban when the avg is smaller than 0.25 seconds
if( $_SESSION['~h'] > 10 && ($_SESSION['~r']/$_SESSION['~h']) < 0.25 ) $_SESSION['~b'] = true;
?>

只是按照建议来避免SESSIONS,所以我把它建立在文件的基础上,而不必依赖于cookie和会话：

<?php
# get the visitor ip
$i = $_SERVER["REMOTE_ADDR"];
# get the filename and location
$f = './log/'.ip2long($i).'.dat';
# check if the file exists and we can write
if ( is_file($f) ) {
    # get the last filetime
    $a = filemtime($f);
    # get the file content
    $b = file_get_contents($f);
    # create array from hits & seconds
    $d = explode(':',$b);
    # calculate the new result
    $h = (int)$d[0] + 1;
    $s = (int)$d[1] + (time()-$a);  
    # add the new data tot text file
    file_put_contents($f,"$h:$s",LOCK_EX);
    unset($d);
}else{
    # create the file if it doesn't exist hits:seconds
    file_put_contents($f,"1:1",LOCK_EX); #size: 3kb
    # to make sure we can write
    # chmod($f,0755); 
    # set the hits to zero
    $h = 0;
}
# create a result var
$r = $h > 10 ? (float)$s/$h : (float)1;
# calculate the diff after 10 hits,and ban when the avg is smaller than 0.20 seconds (5 hits per second)
if( $r < 0.20 ) {
    # check if we can open htaccess
    $fp = @fopen('./.htaccess','a'); 
    if($fp){
        # add the ip to htaccess
        @fwrite($fp,"rndeny from $i"); 
        # close
        @fclose($fp);
        # mail the admin
        @mail("email","Ip: $i with $r sbh (Seconds Between Hits)");
    }
    # let the user know why we deny him or her access
    die('To many requests.');
    # remove the file
    unlink($f);
}
# if the user leaves,reset
if( $r > 30 ) {
    unlink($f);
}
echo 'Result: '.$r.'sbh (Seconds Between Hits)';
?>