If you are looking for a (very) comprehensive list of Linux Monitoring Tools which cover all the Linux elements like network, server, infrastructure, desktop performance, etc. then look no further.
This article at UbuntuPit is an evergreen content which will be updated regularly with more useful Linux Monitoring Tools and the best place to learn about the uncountable options you have.
Happy server monitoring!
ubuntupit.com/most-comprehensive-list-of-linux-monitoring-tools-for-sysadmin/