Check_MK is a complex addon for Nagios/Icinga and consists of three subprojects. The check and inventory system Check_MK is a general purpose Nagios plugin for retrieving data. It adopts a new approach for collecting data and obsoletes NRPE, check_by_ssh, NSClient, and check_snmp. It features a significant reduction of CPU use on the Nagios host and automatic inventory of items to be checked, and is especially useful with larger Nagios installations. "MK Livestatus" gives immediate and fast access to live and historic Nagios status data. It's a supported backend for many addons including NagVis, NagiosBP, and Thruk. "Check_MK Multisite" is a feature complete replacement for the Nagios GUI, and uses MK Livestatus as a backend. It is very fast, and supports efficient distributed monitoring.
Sagan can alert you when events are occurring in your syslogs that need your attention right away. It can store events into a Snort database, so your IDS/IPS data and log data are in the same place. This enables a single console, like Snorby or BASE, to view not only your IDS/IPS data but your log (syslog, SNMP, etc.) data as well. Sagan will correlate the data for you. It also uses 'Snort-like' rule sets, which means it is compatible with Snort rule set management software. It supports multiple output formats that any network administrator will find useful. Sagan can also stop threats based on log analysis via "Snortsam". This allows Sagan to communicate with various types of network devices (Cisco routers/ASA/etc., Linux iptables, etc).