PHP、.htaccess、DDoS 和快速请求保护

Question

我有一个问题，我构建了这个小脚本来检查某个 ip 是否正在淹没我的网站。当它出现时，我拒绝 .htaccess 文件中的 ip。我的问题是，有人可以告诉我这个脚本是否完全无用或值得尝试...该脚本在配置文件中调用，因此它在每次页面加载时运行。

<?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,"\r\ndeny 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;
?>

只是听从了避免 SESSIONS 的建议，所以我让它基于文件，而不必依赖于 cookie 和 session :

<?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,"\r\ndeny from $i"); 
        # close
        @fclose($fp);
        # mail the admin
        @mail("email","IP Banned","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)';
?>

Answer 1

如果您想阻止临时用户在特定时间内发送过多请求，那么是，该脚本可以工作。调出一个验证码屏幕，您就可以开始工作了。

但是

真正的答案是不。

此代码的主要错误是根据 session 来确定用户事件的频率。 “好”的攻击者可以用禁用 cookie 的请求淹没您的服务器，并欺骗他/她的 IP。

阻止攻击的一种方法是进入服务器级别，并安装 iptables。事实上，iptables 与大多数 Linux 发行版一起提供。它几乎不需要配置，开箱即用。

另一种方法，如果您对服务器具有根访问权限，则将 session 处理移至 Memcached。有个功能叫防洪，挺BOSS的。

防止 DDOS 的另一种方法是来自第三方服务，例如 block dos http://www.blockdos.net/

有点贵，但它对你有用。

但是 PHP 本身无法配置为处理 DDOS 攻击。在转到 PHP 脚本之前，您需要在所有要审查的请求前放置某种设备或防火墙。