Aimed at small businesses, ClearOS combines a gateway, server and networking features in a single download. Key features include multi-WAN, VPN, firewall, anti-malware, anti-spam, intrusion prevention, content filtering, file and print services, mail server, Web server, groupware, and more. Although additional services and support are available with a subscription, the full "enterprise" version of the software is available for free. Operating System: Linux.
You can spend thousands on a Gateway security appliance to protect your network, or you can make your own with Endian Firewall Community and an old PC. It includes stateful inspection firewall, VPN, gateway anti-virus, anti-spam, web security, email content filtering, and more. If you prefer a pre-configured appliance or need support, you can also purchase both hardware and software appliances from Endian. Operating System: Linux.
Like Endian, Untangle gives you the option of building your own gateway security appliance with free software and your own PC or purchasing an appliance from the company. It includes a Web filter, virus blocker, spam blocker, ad blocker, firewall, QoS, intrusion prevention, protocol control, OpenVPN, and many other features. Operating System: Linux.
4. NetCop UTM
Available as either a free open source download for up to five concurrent users or in an enterprise version for unlimited users, NetCop offers the same functions as Endian and Untangle and the commercial UTMs. However, it is not available as a pre-configured appliance. Operating System: Linux.