Wikipedia
ClearOS is a software company located in Utah, US and is better known for developing the ClearOS system. ClearOS System (formerly named ClarkConnect) is a Linux distribution, based on CentOS and Red Hat Enterprise Linux, designed for use in small and medium enterprises as a network gateway and network server with a web-based administration interface. It is designed to be an alternative to Windows Small Business Server. ClearOS succeeds ClarkConnect. The software is built by ClearFoundation, and support services can be purchased from ClearCenter. ClearOS 5.1 removes previous limitations to mail, DMZ, and MultiWAN functions.
As of the ClearOS 6.1 release, the distribution is a full-featured operating system for servers and workstations built from source packages for Red Hat Enterprise Linux.