Affiliate Citizen

Lets Start with a Bang!

Ok so to kick off the new blog im going to post about a technical solution to a problem that was raised recently on the A4U forum. The subject raised was how to implement affiliate link masking using a server side scripting language. Now as im fairly fluent in PHP and have also made said scripts it seems a great idea to share them. You need to be able to code a little in PHP to use this and also able to upload to your server (which im assuming most readers should be able to do!).

The Elements

There are three elements we need to get the masking going:

• The robots.txt file - a simple txt file than is specifically targeted towards controlling the behaviour of search engine robots. Its proper purpose is to restrict some areas of websites that are considered private or have some kind of security sensitivities, or, are out of date.
• The redirect page. In this case we we call our page redirect.php - easy.
• The new affiliate links. These will be the links to the redirect page that you will need to write into your pages when everything is in place.

The Robots.txt File

Open up a text editor of your choice (notepad for purists ;)) and the following code is all you will need:

User-agent: googlebot
Disallow: redirect.php
User-agent: msnbot
Disallow: redirect.php
User-agent: slurp
Disallow: redirect.php

The ‘User-agent’ refers to the robot of a certain search engine. So googlebot for Google and msnbot for MSN etc. Different search engines have different bot names so if you want to block others aside from the big three you’ll need to find out their descriptions before you go ahead and add lines to your robots.txt file. The ‘disallow’ line tells the robot that it cannot crawl that file. In this case the redirect.php file will be in the root of the server to make it easier.  Save and upload your completed robots.txt file to the root of your server.

The Redirect Page

Open up your favourite text editor or website creator and begin a new PHP file. You’ll need to add the following lines of code:

<?
$linkid = $_GET['linkid'];
if ($linkid == "") {$link = "http://www.yoursite.com";}
if ($linkid == "1") {$link = "http://www.merchant1.com/";}
if ($linkid == "2") {$link = "http://www.merchant2.com/";}
header("Location: $link");
exit();
?>

Lets look at the code. The $linkid variable is provided in the links we will use from the pages with affiliate links on  -  more on that in a moment. Each link is assigned a number and placed into a conditional statement. The statement compares the $linkid value and assigns the $link variable the correct url. The final two lines then forward the browser to the $link location url using the header function in php. Add as many links as you need, most probably every time you add a new link to your site that needs masking. Save this file as redirect.php and upload to the root of your PHP enabled server. We now need one more essential element….

The New Affiliate Links

Previously your links may have looked like this for all to see:

http://scripts.affiliatefuture.com/AFClick.asp?affiliateID=xxxxx&merchantID=xxxx&programmeID=xxxx&mediaID=x

Take the raw affiliate links and place them into your redirect.php file. Assign them numbers as described above. Lets say for now the affiliate future link above is named as ‘1′. Now you are ready to write your new link just like this:

<a href="http://www.yoursite.com/redirect.php?linkid=1">Affiliate Future Merchant Name</a>

And voila! The new link should now go through the redirect page and the search engines (well those that obey the robots.txt file) won’t see it. If you are really paranoid about search engines following afiliate links try adding rel=”noindex, nofollow” to your masked links.

There are many other things you can do with a redirect script to help with analytics and monitoring of your websites, one example is to add popular links (or products) to a database on the fly. Another is to send an email to yourself if a link has been clicked. Ill cover that in another post soon!