In this recipe, you'll learn how to use a background for the legacy network map and deliberate the placement of hosts in specific points on it to make a kind of network status weathermap to see host statuses at a glance in a geographical context. At the time of writing, this method only works for the legacy map, which is available by clicking on (Legacy) to the right of the Map entry in the left-hand side menu.
You will need Nagios Core 4.0 or a newer server and have shell access to change its backend configuration. You should also have at least a couple of hosts configured to place on the map and understand the basics of using the Nagios network map and icons for hosts. These are discussed in the Using the network map and Choosing icons for hosts recipes, both in this chapter.