These two settings inside the index.php file should be changed to random strings. The folder names should also be changed to match as well.

/*
*---------------------------------------------------------------
* SYSTEM FOLDER NAME
*---------------------------------------------------------------
*
* This variable must contain the name of your "system" folder.
* Include the path if the folder is not in the same  directory
* as this file.
*
*/
$system_path = 'system';

/*
*---------------------------------------------------------------
* APPLICATION FOLDER NAME
*---------------------------------------------------------------
*
* If you want this front controller to use a different "application"
* folder then the default one you can set its name here. The folder
* can also be renamed or relocated anywhere on your server.  If
* you do, use a full server path. For more info please see the user guide:
* <a href="http://codeigniter.com/user_guide/general/managing_apps.html">http://codeigniter.com/user_guide/general/managing_apps.html</a>
*
* NO TRAILING SLASH!
*
*/
$application_folder = 'application';

You may be wondering to yourself: “why does it matter?”. It matters when you DO NOT want your application fingerprinted as a codeigniter application by a hacker. One of the first things some of these guys (or gals) do is run a directory fuzzer on your server. That fuzzer makes requests to your server through a list of common directory names. Believe me, the two terms ‘application’ and ‘system’ is early on in that list, I tried it.

Give a hacker as little information about the internals of your program as possible and make it a bit more secure.

Rerouting in CodeIgniter is really simple if you already know how paths work in the framework. You have a controller that is used as the route redirect target. In other words, it picks up the redirected path as its own. Everything other than that is simple CodeIgniter coding. The path can be as many variables large as you may require.

Fairly complex routing systems can be set up this way without the bit of complexity you would have using straight php without a framework.  Below is a short and sweet, step by step simple example of how to accomplish a two variable reroute.

Step By Step

First Step is download CodeIgniter from their website.

Second Step is to unzip it into your server root or a subfolder.

Third Step is to create a .htaccess file that tells apache how to handle requests. This step isn’t necessary if you don’t care about index.php being in your paths. My code is installed in a subfolder named ciredir on my Xampp server in Windows: