check_mk agent install on CentOS 7 by systemd

Here is the steps I install check_mk agent on CentOS 7 by systemd only without xinit.

first scp the rpm package to CentOS server, then install it:
rpm -ivh check-mk-agent-1.2.8p18-1.noarch.rpm

Open the port 6556:
firewall-cmd --permanent --add-port=6556/tcp
firewall-cmd --reload

Double check the status:
firewall-cmd --list-ports
firewall-cmd --list-services

Restart to make sure the check_mk_agent start on boot.

Hope this helps.

check_mk hang on start with mkeventd

1. Starting mkeventd (builtin: snmptrap)...Cannot bind UDP socket for snmptrap to port: Permission denied

2. It just hang and waiting forever on Starting mkeventd (builtin: snmptrap)...

I found a lot files in /opt/omd/sites/(sitename)/var/mkeventd/status.

Have to manually delete the status and history files to start the mkeventd.

check_mk How to fix:Disk Mount Changes showing error

Sometimes few hosts in my check_mk build showing Disk Mount error.

For example:
“Mount options of / – – – – CRIT – mount options are
> > > acl,barrier=0,data=ordered,errors=remount-ro,noatime,rw,user_xattr,
> > > expected are barrier=0,data=ordered,errors=remount-ro,noatime,rw”

But there isn’t any changes recently.

I just su to my site and refresh the hosts manually:

Restart the check_mk, that will make the nonsense error goes away.

check_mk ALL Hoststate down, check_icmp: Failed to obtain ICMP socket: Operation not permitted

I upgrade my production check_mk site to the latest 1.2.8p14.

Suddenly all Hosts shows down.

Restart the site, everything back to normal.

This happens after I update check_mk to the latest stable Version: 1.2.8p14
Hope it helps.

check_mk outdate error message: Disk Mount Changes network interface speed wrong

A lot time I got these kind of wrong error message like:

Disk Mount changes but missing mount option.
Or Network interface 1 is 10GB but should be 1 GB.

Which is just the check_mk output outdate issue.

Here is what I do to refresh the $host in check_mk:

Sometimes I have to restart omd site, but it should be enough to give you back the correct output.

check_mk agent start by systemd Debian Jessie

I use check_mk everywhere.

For the old school, on Debian system you need install xinetd to start it.
But since we have systemd in Debian 8 Jessie, it will be much cleaner to do systemd way.

Here is how I do it:

  1. Fist if you previous using xinetd, stop and remove it.
  2. And run autoremove to cleanup

  3. Then check your check_mk agent version:
  4. Next enable the check_mk in systemd autostart.
  5. Finally start the service.
  6. A special notice, because the systemd not allow the IP rules like xinetd does.
    You will have to update your firewall to restrict other accessing.

    Hope this helps, please let me know if you have any questions.

Increase SNMP ping Timeout Period for Check_MK

If you are monitoring external devices through SNMP like Netapp Storage, it may throw out alert when the Device is busy or the connect time out.

Put thisĀ in your main.mk file:

Let check_mk server check 1 more time before it send alert after the first one fail.
The wait time out increase to 30 seconds.
These lines apply changes on all of your SNMP machines having the tag snmp.

To force checm_mk client and ping run second checking if first one fail, add these into ~/etc/check_mk/main.mk:

Then restart OMD/Check_MK to make it works.

To make all check_mk less sensitive:

Reference: http://mathias-kettner.de/checkmk_configvars.html
http://lists.mathias-kettner.de/pipermail/checkmk-en/2010-December/002241.html

Monitoring Windows Service with Check_MK

I have to Monitoring Windows Service with Check_MK.

The in-house windows application run as a service on Windows Server.

Sometime it crashed without any notification, just need monitoring it by Check_MK.

  1. Check the service name by cmk command:
  2. Run it from the OMD check_mk box:
    For my site:(mdsmonitor):

    The output should be something like:

  3. Add service name into main.mk file:
  4. add 1 line into /opt/omd/sites/mdsmonitor/etc/check_mk/main.mk

  5. Restart OMD to adapt the changes:
  6. Re Scan the service on Host, add the new service from “Missing Services”

Reference:https://mathias-kettner.de/checkmk_windows.html

Centos 7 check_mk agent quick install

  1. First Install the package:
  2. Then Change the /etc/xinetd.d/check-mk-agent:
  3. Start xinetd service:
  4. Allow firewalld on port 6556: