On the CentOS 7, the notify by email command is defined in /usr/local/nagios/etc/objects/commands.cfg
################################################################################
#
# SAMPLE NOTIFICATION COMMANDS
#
# These are some example notification commands. They may or may not work on
# your system without modification. As an example, some systems will require
# you to use "/usr/bin/mailx" instead of "/usr/bin/mail" in the commands below.
#
################################################################################
# 'notify-host-by-email' command definition
define command{
command_name notify-host-by-email
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\
nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /usr/bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is
$HOSTSTATE$ **" $CONTACTEMAIL$
}
# 'notify-service-by-email' command definition
define command{
command_name notify-service-by-email
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOST
ALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$\n" | /usr/bin/mail -s
"** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$
}
The $CONTACTEMAIL$ is defined /usr/local/nagios/etc/objects/contacts.cfg
# Just one contact defined by default - the Nagios admin (that's you)
# This contact definition inherits a lot of default values from the 'generic-contact'
# template which is defined elsewhere.
define contact{
contact_name nagiosadmin ; Short name of user
use generic-contact ; Inherit default values from generic-contact template (defined above)
alias Nagios-Admin_Frank ; Full name of user
service_notification_commands notify-by-email
host_notification_commands host-notify-by-email
host_notifications_enabled 1
service_notifications_enabled 1
email [email protected] ; <<***** CHANGE THIS TO YOUR EMAIL ADDRESS ******
}
###############################################################################
#
# CONTACT GROUPS
#
###############################################################################
# We only have one contact in this simple configuration file, so there is
# no need to create more than one contact group.
define contactgroup{
contactgroup_name admins
alias Nagios Administrators
members nagiosadmin
}
Mailx
First off all, make sure you installed heirloom-mailx.
If you want to user external smtp server, mailx will be a good option, it’s something like this:
$ echo "This is the message body and contains the message" | mailx -v -r "[email protected]" -s "This is the subject" -S smtp="mail.example.com:587" -S smtp-use-starttls -S smtp-auth=login -S smtp-auth-user="[email protected]" -S smtp-auth-password="abc123" -S ssl-verify=ignore [email protected]
If you use Gmail, you need to enable less secure apps settings before you can send mail.
Note, on RHEL or CentOS, you need to add below option:
-S nss-config-dir="/etc/pki/nssdb/"Eg. If your server does support encryption, so we set -S smtp-auth=plain to adopt that, in nagios the setting will be like:
define command{
command_name notify-host-by-email
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /usr/bin/mailx -v -r "[email protected]" -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" -S smtp="smtp.server.com" -S smtp-auth=plain -S smtp-auth-user="nagios" -S smtp-auth-password="password" $CONTACTEMAIL$
}
Notification interval
By default, the Nagios will send you warning or critical alarm every 60 minutes. You can change this by setup the notification_interval parameters in the host definition or Service definition.
Or you can change this globally by change the interval_lengh in the main configuration file nagios.cfg
References
9 mail/mailx command examples to send emails from command line on Linux