A small business server server OS

ClearOS is a powerful network and gateway server designed for the small business and distributed environments.  Though ClearOS comes with an extensive list of features and integrated services, the solution is easy to configure thanks to the intuitive web-based interface.

The open source revolution in the software industry has made it possible to provide ClearOS at no cost.  Among other features, antivirus, antispam, VPN and content filtering are built right into the software -- no need for expensive third party add-ons.  Before making a decision on whether to subscribe to ClearSDN services and updates for ClearCenter, you can take advantage of the free ClearOS download at any time.  One of the most important tasks when deploying server systems is the ongoing monitoring and maintenance.  ClearSDN offers a suite of Gateway and DNS services to make sure your system is up-to-date, secure and running smoothly.........

http://www.clearfoundation.com/