Best Five Open-Source Network Monitoring Tools

Here is a list of what we think is the top five open-source network monitoring tools: 

1. Nagios: A widely used network monitoring system that can monitor network services, hosts, and devices.
2. Zabbix: It supports agent-based and agentless monitoring, as well as SNMP and IPMI
3. Icinga: A fork of Nagios that aims to provide improved performance, scalability, and flexibility.
4. Cacti: A web-based network monitoring and graphing tool that can monitor a variety of network devices and services.
5. LibreNMS: It supports SNMP, Syslog, and SNMP Trap monitoring, and has a web-based interface for configuration and management.