ClearOS

Join Windows® clients to the domain and manage them transparently. No disruption to your users, no user or device CALs. Comes with industry-standard SMTP and POP3/IMAP mail server built upon the most established technologies and protocols. Guarantees reliable and secure Internet access and helps to manage all the basic network infrastructure services. Receive software updates until the EOL-date of each version and get support when needed. Zentyal offers an easy to use Windows Server® alternative. It comes with native compatibility with Microsoft Active Directory® allowing you to join Windows® clients to the domain and manage them easily, causing no disruption to your users. Zentyal includes the industry-standard SMTP and POP3/IMAP mail servers built upon the most established technologies and protocols. Gives you the opportunity to deploy Zentyal as a mail server, domain & directory server with mail or all-in one server.

IPFire is a hardened, versatile, state-of-the-art Open Source firewall based on Linux. Its ease of use, high performance in any scenario, and extensibility make it usable for everyone. Security is the highest priority in IPFire. It is hardened to protect itself from attacks from the Internet and prevents attacks on your network. Its powerful firewall engine and intrusion prevention system protect your network against attacks from the Internet and denial-of-service attacks. IPFire is free software developed by an open community and trusted by hundreds of thousands of users from all around the world. The primary objective of IPFire is security. It's easy to configure a firewall engine and an intrusion prevention system stops any attackers from breaking into your network. In the default configuration, the network is split into various zones with different security policies such as a LAN and DMZ to manage risks inside the network and have a custom configuration for specific needs.