pfSense - pfSense is a free and open source firewall and router that also features unified threat management, load balancing, multi WAN, and more
Zabbix - Track, record, alert and visualize performance and availability of IT resources
Meraki MX Firewalls - Cloud managed networking from Cisco Meraki. The easiest and most IT-friendly solution for enterprise networking needs.
Datadog - See metrics from all of your apps, tools & services in one place with Datadog's cloud monitoring as a service solution. Try it for free.
SonicWall TZ - Get high-speed threat prevention in a flexible, integrated security solution with the SonicWall TZ Series.
Prometheus - An open-source systems monitoring and alerting toolkit.