Nagios XI - Monitoring the Nagios XI "localhost"


This guide on Best Practices is about monitoring the Nagios XI server itself and what services you could deploy.


Monitoring the Nagios XI "localhost"

Do you know how your XI server is performing?

  • Services you should ideally be monitoring

    • crond, httpd, mysqld, ndo2db, npcd, ntpd, postgresql

      • postgresql is not used on fresh installations of XI 5.x onwards. If you upgraded to XI 5 from a previous version postgres is still used.

    • snmptrapd and snmptt are not present until you follow the XI SNMP Trap procedure

    • The plugin called check_init_service that is part of the linux-nrpe-agent.tar.gz package can be used to monitor these services

      • Requires the following line in /etc/sudoers

        • nagios ALL=NOPASSWD: /usr/local/nagios/libexec/check_init_service
      • Your command definition needs to be:
        • sudo $USER1$/check_init_service $ARG1$


  • File counts - check these folders to make sure the temp files are being processed

    • NPCD Perfdata spool directory

      • /usr/local/nagios/var/spool/perfdata/
    • xidpe spool directory

      • /usr/local/nagios/var/spool/xidpe/
    • Check results folder

      • /usr/local/nagios/var/spool/checkresults/
    • snmptt spool folderNOTE: These locations can vary if a RAM Disk has been implemented 

      • /var/spool/snmptt/
    • Use the Folder Watch wizard to create services to monitor these folders


  • Has the nagios user account expired?

    • From:

      • use lib ".";
    • To:

      • use lib "/usr/local/nagios/libexec";


  • root mailbox size

    • If you’re not a Linux person then you probably don’t know about the system mailbox. This is a local mail system on the linux server where messages are sometimes sent.

    • Certain components used in Nagios XI such as MRTG will send messages to this mailbox when it has a problem. An incorrect MRTG configuration can cause a message to be sent every five minutes as this is when MRTG runs. That’s about 288 messages a day. Over time the root mailbox can grow to GB in size causing issues. I wrote a plugin which can monitor this and let you know when it gets too big.

    • box293_check_mbox.plis the plugin you can use

    • File permission changes required:

      • setfacl -m u:nagios:r-- /var/spool/mail/root



  • Overall Load

    • This service is included by default in Nagios XI
    • check_load is the plugin included with Nagios XI (5) 



  • Swap Usage

    • If the system runs out of physical memory and starts swapping to disk, the system performance will be greatly impacted.

    • This service is included by default in Nagios XI

    • check_swap is the plugin included with Nagios XI (5)


  • Disk Free

    • Disk free space is very important.

    • This service is included by default in Nagios XI however it only monitors /

    • If you have different volumes mounted then you should be monitoring each one of these.

    • check_disk is the plugin included with Nagios XI (5)



Final Thoughts

For any support related questions please visit the Nagios Support Forums at:

Posted by: - Mon, May 2, 2016 at 10:04 PM. This article has been viewed 2161 times.
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