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Well i have this in my forums, i got it a while back off the internet somewhere.
Code:
<?php

/*
CHMOD /iplog/ to 777
Create and CHMOD /iplog/iplogfile.dat to 666
add the following line in any important .php file in the same directory as your anti_dos.php file so it can check IPs when that file is loaded, best example is index.php if you have it.
include("anti_dos.php"); //anti-DoS, prevents rapid accessing

if you have a known cookie on your site,
you can use this, otherwise just ignore this, it will set a different limit
for people with this cookie

I use yourothercookie as the cookie ID for the forum, my forum uses ID
greater than 0 for all members and -1 for guests and members who have logged out,
so making it match greater than zero means members will get better access and
guests with or without cookies won't

Also I use these cookies in the "flood alert" emails to make sure an important user didn't get banned. Someone could fake a cookie, so always be suspicious. Tez
*/
$cookie = $_COOKIE['yourcookie'];
$othercookie = $_COOKIE['yourothercookie'];


if($cookie && $othercookie > 0) $iptime = 20;  // Minimum number of seconds between visits for users with certain cookie
else $iptime = 10; // Minimum number of seconds between visits for everyone else


$ippenalty = 60; // Seconds before visitor is allowed back


if($cookie && $othercookie > 0)$ipmaxvisit = 30; // Maximum visits, per $iptime segment
else $ipmaxvisit = 20; // Maximum visits per $iptime segment


$iplogdir = "./iplog/";
$iplogfile = "iplog.dat";

$ipfile = substr(md5($_SERVER["REMOTE_ADDR"]), -2);
$oldtime = 0;
if (file_exists($iplogdir.$ipfile)) $oldtime = filemtime($iplogdir.$ipfile);

$time = time();
if ($oldtime < $time) $oldtime = $time;
$newtime = $oldtime + $iptime;

if ($newtime >= $time + $iptime*$ipmaxvisit)
{
touch($iplogdir.$ipfile, $time + $iptime*($ipmaxvisit-1) + $ippenalty);
$oldref = $_SERVER['HTTP_REFERER'];
header("HTTP/1.0 503 Service Temporarily Unavailable");
header("Connection: close");
header("Content-Type: text/html");
echo "<html><body bgcolor=#999999 text=#ffffff link=#ffff00>
<font face='Verdana, Arial'><p><b>
<h1>Temporary Access Denial</h1>Too many quick page views by your IP address (more than ".$ipmaxvisit." visits within ".$iptime." seconds).</b>
";
echo "<br />Please wait ".$ippenalty." seconds and reload.</p></font></body></html>";
touch($iplogdir.$iplogfile); //create if not existing
$fp = fopen($iplogdir.$iplogfile, "a");
$yourdomain = $_SERVER['HTTP_HOST'];
    if ($fp)
    {
    $useragent = "<unknown user agent>";
    if (isset($_SERVER["HTTP_USER_AGENT"])) $useragent = $_SERVER["HTTP_USER_AGENT"];
    fputs($fp, $_SERVER["REMOTE_ADDR"]." ".date("d/m/Y H:i:s")." ".$useragent."\n");
    fclose($fp);
    $yourdomain = $_SERVER['HTTP_HOST'];
    
    //the @ symbol before @mail means 'supress errors' so you wont see errors on the page if email fails.
if($_SESSION['reportedflood'] < 1 && ($newtime < $time + $iptime + $iptime*$ipmaxvisit))
    @mail('flood_alert@'.$yourdomain, 'site flooded by '.$cookie.' '
    .$_SERVER['REMOTE_ADDR'],'http://'.$yourdomain.' rapid website access flood occured and ban for IP '.$_SERVER['REMOTE_ADDR'].' at http://'.$yourdomain.$_SERVER['REQUEST_URI'].' from '.$oldref.' agent '.$_SERVER['HTTP_USER_AGENT'].' '
    .$cookie.' '.$othercookie, "From: ".$yourdomain."\n");
    $_SESSION['reportedflood'] = 1;
    }
    exit();
}
else $_SESSION['reportedflood'] = 0;

//echo("loaded ".$cookie.$iplogdir.$iplogfile.$ipfile.$newtime);
touch($iplogdir.$ipfile, $newtime); //this just updates the IP file access date or creates a new file if it doesn't exist in /iplog
?>
Sorry, what is to stop them removing the cookie?
Hm, I wasn't aware that it was possible to do such a thing in PHP.

Good find.
Will this prevent a large attack? Looks like it will only work on smaller attacks.
I haven't tested it with a large attack yet.
(02-22-2010, 03:12 PM)ßeowulf Wrote: [ -> ]Hm, I wasn't aware that it was possible to do such a thing in PHP.

Good find.

It's not. The fact that you run a script is a severe problem. Apache will stop working easy from this script and you can also create filesystem issues.

Don't use this script. It won't effective against any DDOS attack that it's meant to prevent.

This could be rewritten though to instead write to htaccess a deny line. Which would be more effective.
Yes Yes Yes
But what if your computer is attacked by a beaver or worse? how will that script help then? hmmmmmmm

I ask you this with confidence in your response
Ben, your going to get banned extremely quickly.
dude i have +4 rep

they love me.....
and why would i get banned. not as if its a headless woman as my sig
(02-22-2010, 10:15 PM)Omniscient Wrote: [ -> ]It's not. The fact that you run a script is a severe problem. Apache will stop working easy from this script and you can also create filesystem issues.

Don't use this script. It won't effective against any DDOS attack that it's meant to prevent.

This could be rewritten though to instead write to htaccess a deny line. Which would be more effective.
Alright thanks for that Omni,i am having this closed because i don't want to give a bad script.
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