ClearOS is a powerful network and gateway server designed for small organizations and distributed environments. If the description sounds more familiar than the name, that is because this project was formerly known, and loved, as ClarkConnect. ClearOS turns a PC into a dedicated Internet gateway, firewall and server. It does not run alongside other software, ClearOS is a compete operating system that takes over the computer. For small to medium sized offices, the demands on such a server can be modest so ClearOS can be installed on an older PC.
ClearOS provides all the functions needed of an office server, from firewall protection and virus scanning of incoming mail to web and mail servers for the office. It can also act as a web proxy, reducing the amount of bandwidth used by the office, and has traffic shaping and bandwidth management features. These mean that you can ensure that the most important tasks, such as email, are never swamped out by large downloads.
Groupware, file sharing and printer services are also available. The mail server scans incoming mail for spam and malicious attachments, moving suspect mails to a quarantine where they can be safely dealt with. ClearOS can also archive copies of all incoming and outgoing mails. ClearOS is free but there are professional support services available.