Webmin - Webmin is a web-based interface for system administration for Unix.
TinyWall - Lightweight and non-intrusive firewall
ClearOS - A very good alternative for Windows Server, for free
SonicWall - SonicWall security solutions protects your network, systems, users and data from cyber threats.
cPanel - With its first-class support and rich feature set, cPanel & WHM has been the web hosting industry's most reliable, intuitive control panel since 1997.
pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more