pg_activity is a top like application for PostgreSQL server activity
An eye on your system
Open source monitoring system and time series database
Monitorix is a free, open source, lightweight system monitoring tool
A fancy self-hosted monitoring tool
Storage, SAN, LAN Performance Monitoring: IBM,NetApp,Hitachi,HPE,EMC
Tool to ping hosts through firewalls blocking ICMP
Xplico is a Network Forensic Analysis Tool (NFAT)
A cross platform http sniffer with a web UI
Python3 tool to scan, detect and control chromecast devices
REST interface and configuration GUI for Nagios
Apache module for SNMP monitoring
PotHead
Open source tool to monitor your servers and websites
Scalable, distributed monitoring system for high-performance computing
Monitor Apache using SNMP
Highly configurable SNMPv1/v2c/v3 application-level proxy
Network performance monitoring and logging script for Cisco devices.