I’ve been playing with configuring a new nagios running on a Linux host which’s aim is to monitor few Windows servers.
The Linux host’s exim is configured to act as relay host to another SMTP server, so all email ending up in the Linux localhost on port 25 is forwarded to the remote SMTP.
The remote smtp only allows the Linux to send email only in case if a real existing firstname.lastname@example.org is passed it, otherwise it rejects mail and does not sent properly the email.
As the newly configured Nagios installatio is supposed to do e-mail notification, I was looking for a way to change the default user with which Nagios sends mails, which is inherited directly after the username with which /usr/sbin/nagios3 and /usr/sbin/nrpe are running (on Debian this is email@example.com).
Thanksfully, there is a work around, I’ve red some forum threads explaning that the username with whch nagios sends mail can be easily changed from /etc/nagios3/commands.cfg by passing the -a “From: firstname.lastname@example.org” to all occurance of /usr/bin/mail -s , its preferrable that the -a email@example.com is inserted before the -s “” subject option. Hence the occurance of mail command should be changed from:
| /usr/bin/mail -s "** $NOTIFICATIONTYPE$
| /usr/bin/mail -a "From: firstname.lastname@example.org" -s "** $NOTIFICATIONTYPE$
Now to read it’s new configurations nagios requirs restart:
debian:~# /etc/init.d/nagios3 restart
Now in case of failed services or Hosts Down nagios will send it’s mail from the custom user email@example.com and nagios can can send mail properly via the remote relay SMTP host 😉