Please see the INSTALLATION file or the Install guide at the apache vcl
site. (https://cwiki.apache.org/VCL/vcl-23-installation.html)
This file is only a list of requirements, which are also stated in the Install guide.

System Requirements:

Web Frontend:
Apache HTTP Server v1.3 or v2.x with SSL enabled
php 5.0 or later
php modules (some of these may be built in for your distro):
- php-gd
- php-json
- php-mysql
- php-openssl
- php-sysvsem
- php-xml
- php-xmlrpc
- php-gettext
- php-ldap (if you will be using ldap authentication)
- php-process (for RHEL/CentOS 6)

Database:
MySQL 5.0 or later

Management Node Backend:
OS - tested on CentOS 5, RedHat Advanced Server 4,5, and 6
Packages:
- expat
- expat-devel
- gcc
- krb5-libs
- krb5-devel
- libxml2
- libxml2-devel
- openssl
- openssl-devel
- perl-CPAN
- perl-DBI
- perl-DBD-MySQL
- perl-Digest-SHA1
- perl-MailTools
- perl-Net-Netmask
- perl-Net-SSH-Expect
- perl-RPC-XML
- perl-XML-Simple
- perl-YAML
- xmlsec1-openssl
- MySQL 5 client
- Nmap security scanner
- OpenSSH client
- Perl 5.8.x

Management Node Perl Modules:
The Perl modules listed below are available from CPAN (www.cpan.org) and are
distributed under one or more of the following licenses:
- The "Artistic License"
- GNU General Public License (GPL)
- GNU Library or "Lesser" General Public License (LGPL)
Some of the required Perl modules may be built into your distribution. A script
is provided which attempts to install the Perl modules. See the "Installing
Required Perl modules" section of the INSTALLATION file.
- Crypt-SSLeay  
  http://search.cpan.org/dist/Crypt-SSLeay/
  License: Perl Artistic & GPL
- DBI  
  http://search.cpan.org/dist/DBI/
  License: Perl Artistic & GPL
- Devel-StackTrace  
  http://search.cpan.org/dist/Devel-StackTrace/
  License: Perl Artistic & GPL
- Exception-Class  
  http://search.cpan.org/dist/Exception-Class/
  License: Perl Artistic & GPL
- HTML-Parser  
  http://search.cpan.org/dist/HTML-Parser/
  License: Perl Artistic & GPL
- IO-Compress  
  http://search.cpan.org/dist/IO-Compress/
  License: Perl Artistic & GPL
- libwww-perl  
  http://search.cpan.org/dist/libwww-perl/
  License: Perl Artistic & GPL
- MailTools  
  http://search.cpan.org/dist/MailTools/
  License: Perl Artistic & GPL
- Object-InsideOut  
  http://search.cpan.org/dist/Object-InsideOut/
  License: Perl Artistic & GPL
- RPC-XML  
  http://search.cpan.org/dist/RPC-XML/
  License: Perl Artistic & LGPL
- Scalar-List-Utils 
  http://search.cpan.org/dist/Scalar-List-Utils
  License: Perl Artistic & GPL
- XML-Parser  
  http://search.cpan.org/dist/XML-Parser/
  License: Perl Artistic & GPL
- YAML  
  http://search.cpan.org/dist/YAML/
  License: Perl Artistic & GPL
- URI  
  http://search.cpan.org/dist/URI/
  License: Perl Artistic & GPL
- Digest-SHA1 
  http://search.cpan.org/dist/Digest-SHA1/
  License: Perl Artistic & GPL

Management Node Backend Conditional System Requirements:
- Bare-metal and virtual machine provisioning
  Both bare-metal and virtual machine provisioning require a DHCP server running
  on the management node listening on the private network.
- Bare-metal provisioning
  If you want to provision bare-metal or physical computers such as blades. You
  will need xCAT setup and working. This release supports either xCAT 1.3 or
  xCAT 2.x. This is useful for very large setups, very custom environments, HPC
  integration, automating VM host servers either ESX standard or VMware Free
  Server. Imaging support using xCAT 2.x is an add on feature. To enable imaging 
  for xCAT2.X See adding support for partimage and partimage-ng to xCAT 2.x in the vcl apache wiki. 
- VMware virtual machine provisioning
  If you want to provision virtual machines on ESX,ESXi, or VMWare Free server 2.x you will need the
  VMware vSphere toolkit. This toolkit can be obtained from:
  http://www.vmware.com/support/developer/viperltoolkit/
  This toolkit is a set of Perl modules. The toolkit is not required if using
  VMware Free server 1.x.
- Windows XP/2003/Vista//7/2008
  If provisioning Windows OS on bare-metal, you will need the following:
  - Sysprep - used for preparing Windows environments before an image is
	 captured
- Jabber Instant Message Notification(optional)s
  VCL has the ability to send instant message notifications using Jabber. This
  feature is optional and can be enabled or disabled by configuring the
  "jabber=[yes|no]" property in the vcld.conf file. If Jabber notification
  feature is enabled, the following Perl modules need to be installed:
  - Net-Jabber
    http://search.cpan.org/dist/Net-Jabber/
    License: Perl Artistic and GPL
  - Net-XMPP
    http://search.cpan.org/dist/Net-XMPP/
    License: LGPL
  - Module-Build
    http://search.cpan.org/dist/Module-Build/
    License: Perl Artistic and GPL
  - XML-Stream
    http://search.cpan.org/dist/XML-Stream/
    License: Perl Artistic and GPL
  - Authen-SASL
    http://search.cpan.org/dist/Authen-SASL/
    License: Perl Artistic and GPL
  - Digest::SHA1 
    http://search.cpan.org/dist/Digest-SHA1/
    License: Perl Artistic and GPL


Bundled 3rd Party Software
A copy of Dojo Toolkit version 1.6.1 is included in the web code under
web/dojo.
Portions of the phpseclib (http://phpseclib.sourceforge.net) project are
included in the web code under web/.ht-inc/phpseclib.