Assimilation System Management Suite
The Assimilation Suite discovers systems, services, network connections, configuration and dependencies, IP and MAC addresses. This all goes into a continually updated graph-based configuration management database (CMDB). This is then compared and scored against best practices, services and servers are monitored - all with near-zero configuration - in a way that scales to hundreds of thousands of servers. It also provides visualization tools, APIs for sending alerts to humans and other systems, and a variety of canned reports (queries) to aid in securing and managing systems, hooking into ChatOps, and creating plans for triaging your security issues
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collectd
A daemon that collects system performance statistics periodically, and provides tons of plugins to store and analyze these values
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Eucalyptus
An open source software for building Amazon EC2-compatible private and hybrid cloud platforms
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Honeybadger
Honeybadger is a hosted monitoring service that tracks errors happening in your applications, aggregates them, and notifies you about them based on rules you define. Honeybadger gives you the insight you need to diagnose and fix application errors, faster.
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Monit
An open source utility for managing and monitoring processes, programs, files, directories and filesystems
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Nagios Core
Nagios Core network monitoring software is a powerful, enterprise-class host, server, application, monitoring and alerting tool
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Netdata
netdata is a system for distributed real-time performance and health monitoring. It provides unparalleled insights, in real-time, of everything happening on the system it runs (including applications such as web and database servers), using modern interactive web dashboards.
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Phabricator
Phabricator is an open source collection of development and code management, including code reviews and audits, browsing repositories, tracking bugs, etc
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Sentry
Automate error tracking to find and fix issues before your users even experience a crash. Sentry is open-source, real-time, and loved by 100,000 developers around the world.
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Supervisord Monitor
Supervisord Monitor is multi server monitoring tool for supervisor - watch, start and stop all your supervisord instances and servvices from one place.
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testssl.sh
A command-line tool which checks a server's service on any port for the support of TLS/SSL ciphers, protocols as well as some cryptographic flaws. It's designed to provide clear output for your "is this good or bad" decision.
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Zabbix
An open source, enterprise-class monitoring framework
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