For this demonstration I will be configuring NAGIOS to route it's notifications through an Exchange server.
We should firstly define a contact definition - this is simply a set of information that tells NAGIOS when and where to send notifications - once we have defined a contact we can then associate it with hosts, hostgroups, service groups and so on.
So we should edit the contacts definitions:
sudo vi /usr/local/nagios/etc/objects/contacts.cfg
define contact {
contact_name Administrator1
alias Administrator 1
email
[email protected]
service_notification_period 24x7
service_notification_options w,u,c,r,f,s
service_notification_commands notify-service-by-email
host_notification_period 24x7
host_notification_options d,u,r,f,s
host_notification_commands notify-host-by-email
}
We can also create a group as well to house multiple recipients:
define contactgroup{
contactgroup_name MyContactGroup
alias GroupAlias
members Administrator1,Administrator2,Administrator3
}
We can then define this contact within - lets say a specific host:
define host{
name mailserver
use linux-server
notifications_enabled 1
notification_period 24x7
notification_interval 120
notification_options d,u,r,f,s
register 0
contact_groups
Group1
contacts Contact1
}
Our next task is too setup a MTA so we can send our email to the contacts specified - now as I was using the 'Core' edition of CentOS I had instal the 'mail' command:
yum install mailx mutt
The mail command that is issued by NAGIOS is defined within:
sudo vi /usr/local/nagios/etc/objects/commands.cfg
We are looking specifically at the following lines:
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /bin/mail -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$\n" | /bin/mail -s "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$
Although the command being invoked e.g.:
/bin/mail -s "testing subject"
[email protected] < message.txt
does not route the mail through the smarthost and will attempt to deliver it directly - so we must define the '-S' switch to manually specify the smarthost (Exchange.) You should also ensure that a receieve connector is setup and configured correctly in your Exchange environment.
To test your SMTP config we can issue something like:
echo Test | mailx -v -s "Test Subject" -S smtp=mail.domain.com:25
[email protected]
I end up changing the 'command_line' variables (as above) to:
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\nHost: $HOSTNAME$\nState: $HOSTSTATE$\nAddress: $HOSTADDRESS$\nInfo: $HOSTOUTPUT$\n\nDate/Time: $LONGDATETIME$\n" | /bin/mail
-S smtp=mail.myhost.com:25 -s "** $NOTIFICATIONTYPE$ Host Alert: $HOSTNAME$ is $HOSTSTATE$ **" $CONTACTEMAIL$
command_line /usr/bin/printf "%b" "***** Nagios *****\n\nNotification Type: $NOTIFICATIONTYPE$\n\nService: $SERVICEDESC$\nHost: $HOSTALIAS$\nAddress: $HOSTADDRESS$\nState: $SERVICESTATE$\n\nDate/Time: $LONGDATETIME$\n\nAdditional Info:\n\n$SERVICEOUTPUT$\n" | /bin/mail
-S smtp=mail.myhost.com:25 -s "** $NOTIFICATIONTYPE$ Service Alert: $HOSTALIAS$/$SERVICEDESC$ is $SERVICESTATE$ **" $CONTACTEMAIL$
Finally restart nagios and trigger an alert:
sudo service nagios restart
