Tag Archives: Nagios

Getting Ubuntu to send through Gmail for Nagios

Recently I set up a Nagios installation running in a VM on my laptop (Virtualbox on a MacBook Pro).  This was a quick and easy way for me to get some monitoring going without needing a real server somewhere.  (I know, I know – “Use the cloud dumbass!”  It’s complicated).

Anyway, the trickiest part was getting the notifications to actually go to my gmail.com account. Gmail doesn’t accept regular old SMTP connections.  You need to use authentication over TLS (or SSL).  I didn’t know how to set this up, but I found this great page that explains most of it:

Mark Sanborn’s guide to getting postfix to send through Gmail

This guide was written several years ago and while it almost worked for Ubuntu 10.10, two changes were required.

The first change was to use the new Equifax CA cert because the one that Gmail is currently using isn’t part of the postfix config in 10.10, although the right cert is already on the system. Fixing this is very straightforward:

cat /etc/ssl/certs/Equifax_Secure_CA.pem >> /etc/postfix/cacert.pem

The second change is to tell the mail server to actually use the transports file that the guide has you set up. This must have already been there in 2007 but wasn’t there for me. This was a one-line change to /etc/postfix/main.cf:

root@gunther-VirtualBox:/etc/postfix# rcsdiff main.cf
RCS file: RCS/main.cf,v
retrieving revision 1.1
diff -r1.1 main.cf
> # use a transport file to send stuff to google for gmail.com
> transport_maps = hash:/etc/postfix/transport

(Yeah I still use RCS when I’m modifying config files. Try it!
apt-get install rcs ; mkdir RCS ; ci -l file
You’ll love it).

By following the instructions at the link and adding these two steps, my VM was sending email to my gmail.com account and everybody was happy.