ionCube loader is the PHP extension that decodes encrypted PHP files at runtime. Most commercial hosting companies have ionCube loader installed already. But if this is not your case, here’s how to install the loader.

Steps:
[*] Login via SSH to your server as root

[*] Download the loader from ionCube:
wget http://downloads2.ioncube.com/loader_downloads/ioncube_loaders_lin_x86.tar.bz2

Wait until its finished:
--09:20:50-- http://downloads2.ioncube.com/loader_downloads/ioncube_loaders_lin_x86.tar.bz2
Resolving downloads2.ioncube.com... 72.9.241.122
Connecting to downloads2.ioncube.com|72.9.241.122|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 2436435 (2.3M) [application/x-bzip2]
Saving to: `ioncube_loaders_lin_x86.tar.bz2'

100%[====================================================================================================================>] 2,436,435 25.8K/s in 93s

09:22:26 (25.6 KB/s) - `ioncube_loaders_lin_x86.tar.bz2' saved [2436435/2436435]

[*] Extract the loader package:
tar xvjf ioncube_loaders_lin_x86.tar.bz2

[*] Check your PHP version:
php -v

You’ll see something like this:
[root@]# php -v
PHP 5.1.6 (cli) (built: May 24 2008 14:07:53)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies

So, my PHP version is: 5.1
The ionCube module I’ll be used is: ioncube_loader_lin_5.1.so

[*] Copy the ionCube module to PHP modules directory.
cp ioncube/ioncube_loader_lin_5.1.so /usr/lib/php/modules/

[*] Add the module into PHP configuration file
nano /etc/php.d/ioncube.ini

[*] Add the following line:
zend_extension = /usr/lib/php/modules/ioncube_loader_lin_5.1.so

[*] Save and exit from nano.
Ctrl + O
Ctrl + X

[*] Restart Apache
service restart httpd
OR
/etc/init.d/httpd restart
[*] Verify the module:
php -v
You’ll see something like these:
[root@]# php -v
PHP 5.1.6 (cli) (built: May 24 2008 14:07:53)
Copyright (c) 1997-2006 The PHP Group
Zend Engine v2.1.0, Copyright (c) 1998-2006 Zend Technologies
with the ionCube PHP Loader v3.3.11, Copyright (c) 2002-2010, by ionCube Ltd.
[*] Done.

Good luck!