The Concept
There are many forms of link-spam but all rely on a single sticky identifier: The link. Because it is humanly impossible to post thousands of times in an hour to guestbooks, blogs, forums, etc. across the web, link spam is vulnerable to a throttling mechanism. If we could track a large number of posts, we could find and throttle link spam. How do we do that?..

The Method
Unlike many other software-specific spam tools, SLV is universally applicable. It simply takes a bit of text, extracts any urls, checks against a database of recently added urls across the web, and determines if a reasonable threshold has been exceeded. The XML-RPC script returns a 1 for accept and a 0 for reject. This means that any type of web form - whether a post to a guestbook or blog, a forum entry, even an email form - can be protected from link spam.

Key Benefits

1. No API Key or License Needed
2. No Confusing Development - Post or XML-RPC
3. Works with other spam products, the more the merrier!
4. Integrates seemlessly with any blog, guestbook, wiki, or forum
5. Monitors by link, not IP - proxies, connection switching, etc. are useless

Installation Options

1. Pre-Created Modules
2. XML-RPC Call
3. POST Method: Sample PHP Code
4. XML-RPC Call: Sample PHP Code

Pre-created Modules

1. Achim Winkler Guestbook
2. Ardguest Guestbook
3. Fantastic Guestbook
4. Viper Guestbook
5. Xeobook Guestbook
6. PHPBB2

XML-RPC Call
Below is structure of an XML-RPC call to linksleeve, which should be sent to http://www.linksleeve.org/slv.php // call // <methodCall> <methodName>slv</methodName> <params> <param> <value><string>Whatever your input is</string></value> </param> </params> </methodCall> // response // <methodResponse> <params> <param> <value><int>1</int></value> </param> </params> </methodResponse>

POST method via PHP fsockopen()
A very simple integration method. // Change this line below to determine how your software will respond if the message is spam if(simpleSLV(implode(" ",$_POST))=='spam') { } else { } function simpleSLV($opt) { $data = "content=$opt"; $buf = ""; $fp = fsockopen("www.linksleeve.org", 80, $errno, $errstr, 30); $header = "POST /pslv.php HTTP/1.0\r\n"; $header .= "Host: www.linksleeve.org\r\n"; $header .= "Content-type: application/x-www-form- urlencoded\r\n"; $header .= "Content-length: " . strlen($data) . "\r\n"; $header .= "User-agent: Mozilla/4.0 (compatible: MSIE 7.0; Windows NT 6.0)\r\n"; $header .= "Connection: close\r\n\r\n"; $header .= $data; fputs($fp, $header, strlen($header)); while (!feof($fp)) { $buf .= fgets($fp, 128); } fclose($fp); if(!stristr($buf,"-slv-1-/slv-")) { return 'spam'; } else { return 'ham'; } }

XML-RPC method via PHP PEAR
The most common interface used is XML-RPC and PHP, although there are simpler options available. Below is sample code.

// Include the Pear XML-RPC Client Package require_once 'XML/RPC.php'; // Start by turning all data posted into a single input form $input = implode(" ",$_POST); $host = $_SERVER['SERVER_NAME']; $input = str_replace($host,"",$input); // Build the XML-RPC message $params = array(new XML_RPC_Value($input, 'string')); $msg = new XML_RPC_Message('slv', $params); $cli = new XML_RPC_Client('/slv.php', 'http://www.linksleeve.org'); $resp = $cli->send($msg); if (!$resp) { echo 'Communication error: ' . $cli->errstr; exit; } if (!$resp->faultCode()) { $val = $resp->value(); if($val->scalarval()=='1') { //!! THIS IS WHERE YOU WOULD PLACE ANY CONTINUING CODE !!// echo "ACCEPT"; } else { echo "REJECT"; } } else { // HANDLE ERRORS echo 'Fault Code: ' . $resp->faultCode() . "\n"; echo 'Fault Reason: ' . $resp->faultString() . "\n"; }

Thanks again. We have had a problem with people auto-submitting our lead form when fishing for links. It would leave us with 20 fake leads a day. Not anymore!
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