DANOS is described as 'unified network operating system driving innovation across the networking stack. DANOS is based upon Vyatta and uses DPDK so it should be able to forward packets line rate (10G)' and is a Firewall in the Network & Admin category. There are five alternatives to DANOS for Linux, Online / Web-based, BSD and Self-Hosted solutions. The best alternative is pfSense, which is both free and Open Source. Other great apps like DANOS are MikroTik RouterOS (Paid), VyOS (Paid, Open Source), Sophos UTM (Paid) and Endian Firewall Community (Paid, Open Source).
Sophos UTM integrates complete security software within a single appliance. Choose only the protection you need when you need it. And deploy it on the platform that best fits your business: software, hardware or virtual appliance.