sSMTP is a simple, lightweight SMTP delivery agent. Its easy to setup and works great with Nagios. I will document the steps I used to get it working for my Nagios server.
sSMTP is available in the Ubuntu repos and can be installed with the following command:
apt install ssmtp
Once sSMTP is installed, we’ll need to edit main config file and set it to relay to our mail server. I currently use SendGrid since it is external and reliable. Adjust your settings as needed.
nano /etc/ssmtp/ssmtp.conf # # Config file for sSMTP sendmail # # The person who gets all mail for userids < 1000 # Make this empty to disable rewriting. [email protected] # The place where the mail goes. The actual machine name is required no # MX records are consulted. Commonly mailhosts are named mail.domain.com mailhub=smtp.sendgrid.net:587 AuthUser=SendGridUser AuthPass=SendGridPassword #UseSTARTTLS=YES # Where will the mail seem to come from? rewriteDomain=example.com # The full hostname hostname=nagios.example.com # Are users allowed to set their own From: address? # YES - Allow the user to specify their own From: address # NO - Use the system generated From: address FromLineOverride=YES
Now you can test sSMTP and verify you're able to receive emails
echo "Hello, World" | mail -s "sSMTP Nagios Email Test" [email protected]
Now we'll need to change /usr/local/nagios/etc/objects/commands.cfg and change part of notify-host-by-email and notify-service-by-email lines from:
from: /bin/mail to: /usr/bin/mail
Now check to make sure there are not any issues with Nagios' config files and set a server or other device to alert, and you should be good to go.
/usr/local/nagios/bin/nagios -v /usr/local/nagios/etc/nagios.cfg