How to Download install and Configure plugins in GLPI.
Plugins download
You can download the GLPI plugins from GLPI Plugin website
Following categories of plugins are available in the web
inventory, network, management, reports, data, export, helpdesk, import, buying, calendar, ocs-ng, appliances, entities, graphs, logs, meta-plugin, printers, snmp, snort, switchs

Plugin Installation:
Download the required plugins form GLPI website and extract them in the glpi/plugins folder
Login to glpi web as administrator
go to setup->plugin
There you can find the plugin list
To install the plugin click on => Install
To Activate the Plugin click on => Activate

To configure the plugin click on the plugin name. That will open the Plugin configuration page.

Once you have configured the plugin, you can start using it from the plugin menu.