3. Icinga2 Integration

ntopng integrates with Icinga2 by means of a check plugin check_ntopng.py, opensource and freely available.

The plugin connects to the ntopng REST API to query for host alerts. Specifically, it queries:

  • Host engaged alerts, to capture ongoing host network issues (for example, the host is a victim of a SYN flood attack)
  • Host flow alerts, to capture suspicious or malicious flows involving a particular host (for example, the host has been contacted by a blacklisted IP).

The plugin code is available at https://github.com/ntop/ntopng/tree/dev/tools/icinga2 along with other files necessary for Icinga2 to properly interface with the plugin. The integration has been announced at https://www.ntop.org/ntopng/integrating-ntopng-with-icinga2/.

3.1. Plugin Installation and Configuration

To properly setup check_ntopng.py, the following steps are necessary:

  • check_ntopng.py needs to be placed inside the Icinga2 plugins directory
  • An Icinga2 CheckCommand needs to be created so that Icinga2 will know how to interface with the plugin
  • Icinga2 Service s need to be created to tell Icinga2 to execute the plugin as part of its hosts monitoring operations

Let’s see how to perform these steps in detail.

First, download the plugin file check_ntopng.py into the PluginContribDir directory. The path to this directory can be found inside Icinga2 constants.conf file, which is typically located under /etc/icinga2/ under Linux.

To find the path to this directory out, it suffices to grep file constants.conf for PluginContribDir

cat /etc/icinga2/constants.conf | grep PluginContribDir
const PluginContribDir = "/usr/lib/nagios/plugins"

Here the PluginContribDir path is /usr/lib/nagios/plugins.

Once the plugin is in place, it is necessary to download file check_ntopng_command.conf in /etc/icinga2/conf.d/ or in any other directory which is read by Icinga2 upon startup. The file contains the definition of a CheckCommand object, necessary to tell Icinga2 how to interface with the plugin.

Then, download and place file check_ntopng_service.conf in /etc/icinga2/conf.d/ or in any other directory which Icinga2 is aware of. This file contains the definition of two Service objects, one to check for host engaged alerts (“ntopng-icinga-host-health”) and another one to check for host flow alerts (“ntopng-icinga-host-flows-health”). Those two files will automatically apply the services to all the Icinga2 monitored hosts.

Finally, a bunch of constants should be configured to tell Icinga2 how to properly reach and authenticate to the ntopng REST API. Such constants go inside file constants.conf, the same file used above to locate the PluginContribDir directory.

Constants are the following

# cat /etc/icinga2/constants.conf | grep Ntopng
/* Ntopng */
const NtopngHost = ""
const NtopngPort = 3000
const NtopngInterfaceId = 0
const NtopngUser = "admin"
const NtopngPassword = "admin1"
const NtopngUseSsl = false
const NtopngUnsecureSsl = false

NtopngHost and NtopngPort tell Icinga2 how to connect to the ntopng REST API and NtopngUseSsl whether SSL has to be used for the connection (NtopngUnsecureSsl set to true prevents the plugin from checking SSL certificates validity). When the ntopng authentication is enabled, NtopngUser and NtopngPassword are necessary to indicate a user/password pair which will be used by Icinga2 to authenticate to the REST API. Finally, NtopngInterfaceId is used to tell Icinga2 the id of the ntopng interface which is responsible for the monitoring of traffic.

3.2. Example

Let’s say there is a ntopng instance running on ntopng is monitoring two interfaces, namely the loopback lo and enp2s0f0, and it only responds to HTTPS requests on port 443.

ntopng -i lo -i enp2s0f0 -w 0 -W 443

Interface enp2s0f0 is connected to a mirror port of a switch and receives a copy of all the traffic of local network, local network which is also monitored by Icinga2.

A user admin is allowed to access the ntopng GUI, upon successful authentication with password ntopngIcinga2. User admin, by visiting the ntopng GUI page if_stats.lua, finds out that enp2s0f0 has been assigned an id equal to 2 by ntopng.

Given the information above, one would configure Icinga2 constants.conf as follows

# cat /etc/icinga2/constants.conf | grep Ntopng
/* Ntopng */
const NtopngHost = ""
const NtopngPort = 443
const NtopngInterfaceId = 2
const NtopngUser = "admin"
const NtopngPassword = "ntopngIcinga2"
const NtopngUseSsl = true
const NtopngUnsecureSsl = false

After changing the constants.conf one can restart Icinga2 to make sure changes become effective. After the restart, Icinga2 will take each of the monitored hosts in and, by means of the plugin, will ask ntopng to see if there are any alerts, possibly changing its services from OK to CRITICAL.