Question: What is the OS of the comparing firewall appliance that has 550+ employees across the Earth ?

text: Comparison of firewalls
Firewall appliances
In general , a computer appliance is a computing device with a specific function and limited configuration ability , and a software appliance is a set of computer programs that might be combined with just enough operating system ( JeOS ) for it to run optimally on industry standard computer hardware or in a virtual machine . A firewall appliance is a combination of a firewall software and an operating system that is purposely built to run a firewall system on a dedicated hardware or virtual machine . [ 1 ] [ 2 ] [ 3 ] These include : embedded firewalls : very limited-capability programs running on a low-power CPU system , software-based firewall appliances : a system that can be run in independent hardware or in a virtualised environment as a virtual appliance hardware-based firewall appliances : a firewall appliance that runs on a hardware specifically built to install as a network device , providing enough network interfaces and CPU to serve a wide range of purposes . From protecting a small network ( a few network ports and few megabits per second throughput ) to protecting an enterprise-level network ( tens of network ports and gigabits per second throughput ) . The following table lists different firewall appliances .
The following is a comparison of notable firewalls, starting from simple home firewalls up to the most sophisticated Enterprise-level firewalls.
Firewall License Cost OS
Clavister Proprietary Included on all Clavister NGFWs Proprietary operating system cOS Core
Check Point Proprietary Included on Check Point security gateways Proprietary operating system Check Point IPSO and Gaia ( Linux -based )
FortiGate Proprietary Included on all Fortigate devices Proprietary , FortiOS , Based on the Linux kernel
Palo Alto Networks Proprietary Included on Palo Alto Networks firewalls Proprietary operating system PANOS
Sophos Proprietary Included on Sophos UTM Linux -based appliance
Cisco ASA Firepower Proprietary Included on all CISCO ASA devices Proprietary operating system
Cisco PIX Proprietary Included on all CISCO PIX devices Proprietary operating system
Juniper SSG Proprietary Included on Netscreen security gateways Proprietary operating system ScreenOS
Juniper SRX Proprietary Included on SRX security gateways Proprietary operating system Junos
Sonicwall Proprietary Included on Dell appliance Proprietary operating system SonicOS Based on the Linux kernel
Barracuda Firewall Proprietary Included Firewall Next Generation appliance Windows -based appliance embedded firewall distribution
Cyberoam Proprietary Included Firewall Sophos appliance Windows -based appliance embedded firewall distribution
D-Link Proprietary Included Firewall DFL Windows -based appliance embedded firewall distribution
Endian Firewall Proprietary Free / Paid Linux -based appliance
Forcepoint NGFW Proprietary Included on all Forcepoint NGFW devices Proprietary operating system
OPNsense Simplified BSD / FreeBSD License Free / Paid FreeBSD -based appliance firewall distribution
pfSense ESF/ Apache 2.0 Free / Paid FreeBSD -based appliance firewall distribution
Untangle GPL Free / Paid Linux -based appliance firewall distribution
Zeroshell GPL Free / Paid Linux / NanoBSD -based appliance firewall distribution
SmoothWall GPL Free / Paid Linux -based appliance embedded firewall distribution