Icinga

/etc/icinga/objects/generic-service_icinga.cfg 

sudo /etc/init.d/icinga check

0 - OK
1 - warning
2 - critical
3 - unknown

wget http://cdn1.iconfinder.com/data/icons/fatcow/16x16/mail_yellow.png -O /usr/share/nagios/htdocs/images/logos/base/mail.png
wget http://cdn1.iconfinder.com/data/icons/free-business-desktop-icons/16/Telephone.png -O /usr/share/nagios/htdocs/images/logos/base/phone.png
wget http://cdn1.iconfinder.com/data/icons/nuvola2/16x16/devices/printer1.png -O /usr/share/nagios/htdocs/images/logos/base/printer.png

htpasswd /etc/icinga/htpasswd.users icingaadmin

htpasswd /etc/icinga/htpasswd.users foo
sed -i 's|icingaadmin|foo|g' /etc/icinga/cgi.cfg
/etc/init.d/apache2 restart
/etc/init.d/icinga restart

su -s /bin/bash nagios
ssh-keygen -f "/var/lib/nagios/.ssh/known_hosts" -R backup.example.com
ssh backup.example.com

sed -i 's|check_external_commands=0|check_external_commands=1|g' /etc/icinga/icinga.cfg
chmod 2710 /var/lib/icinga/rw
 
# fix permissions for external commands
dpkg-statoverride --update --add nagios www-data 2710 /var/lib/icinga/rw
chown nagios:nagios /var/lib/nagios /var/lib/icinga/ -R
chown nagios:www-data /var/lib/icinga/rw /var/cache/icinga/ -R

# get hosts with issues
curl -s -u "foo:bar" -k "https://monitoring.example.com/icinga/cgi-bin/status.cgi?servicestatustypes=20&noheader=1&servicestatustypes=29&sorttype=2&sortoption=3&scroll=963&jsonoutput"  | \
  jq --raw-output ' .status.service_status[] | select(.host_name | contains("dev")) | select(.status_information | contains("Apache", "Java")) | .host_name'

sed -i 's|debug_level=0|debug_level=16|g' /etc/icinga/icinga.cfg
tail -f /var/log/icinga/icinga.debug

https://mod-gearman.org/download.html
apt install -y mod-gearman-worker
vi /etc/mod-gearman/worker.conf
/etc/init.d/gearman-job-server restart
/data/mod_gearman/bin/gearman_top

apt install -y nagios-nrpe-server
cat /etc/nagios/nrpe.d/nrpe.cfg 
allowed_hosts=10.0.10.192
command[check_apt]=/usr/lib/nagios/plugins/check_apt