Creating a network host hierarchy

In this recipe, you'll learn how to establish a parent-child relationship for two hosts in a very simple network in order to take advantage of Nagios Core's reachability logic. Changing this configuration is very simple; it involves adding only one directive and optionally changing some notification options.

Getting ready

You will need to run Nagios Core 4.0 or a newer server and have at least two hosts, one of which is only reachable via the other. The host that allows communication with the other is the parent host. You should be reasonably confident that a loss of connectivity to the parent host necessarily implies that the child host will become unreachable from the monitoring server.

Access to the web interface of Nagios Core would also be useful as making this change will change the appearance of the network map; this is discussed in the "Using the network map" recipe in this chapter.

Our example will use a Nagios Core monitoring server, olympus.example...