How do network monitoring programs like Cacti and Nagio work?

Question

How do network monitoring programs like Cacti and Nagio work?

Answer 1

Nagios uses both plugins that do active scanning for various conditions (such as scheduled ping scans, testing that tcp is listening on a particular interface, or doing an ldap bind to the ldap server to verify that the service is running). most of these are using simple common widely available linux commands to test the condition of a networked service. Nagios can also recognize 'passive' events sent from snmp/rmon or other system monitor conditions



Nagios schedules these active tests to run at a specific interval (default is 5 minutes) and logs the "status" of the results. (either "OK", "Warning", "Critical" or "unknown" - plugins can also be modified to log the results of their tests for analysis with trending tools (for instance we log the results of running several tools so we can use a trend analyzer like cacti to create charts from the results)



We generally use NAGIOS for the active monitoring of services and to provide notification when certain conditions occur. We generally use CACTI to give us trending information on service availability and load.

Answer 2

network montioring app in stalled on the server and then you can monitor all network pcs from your own computer, more info: http://www.monitoring-softwares.com/

Answer 3

Network monitoring programs monitor your network by analizing the lines, the data transcieving and testing connections...



However network monitoring tools can become the biggest lag on a network due to its constant strain on the network...



If you want to find out why your network isn't up to par run a network monitoring program, if you want to find out why your internet connection is so slow, do not run a network monitoring program... you will only make it slower. Also on a network with 25 nodes are more... anything less isnt worth the tax network monitors put on the network.