Create a Custom Sensor using the API

Using the API it is possible to create a custom sensor that provides you with this information.

But what if this sensor suddenly goes into a warning state?

Alternative Approach to the "Best Answer"

I would suggest to use customized web page template for the PRTG webserver, that displays the number of sensors in paused/warning/OK etc. status, plus a HTTP content sensor, that monitors this value.

Step 1: Creating your own API function

• Create a new textfile "getsensorsbystate.htm" in the \website\api folder of your PRTG installation. Note: As of PRTG Network Monitor 13.2.3, the folder is \webroot\api. See this article for details.
• Edit the file in a text editor, paste the following code, and save the file:

[<#graph graphcontent="statusoverview" show="textraw">]

Step 2: Creating a HTTP Content sensor to monitor the value

Create a new HTTP Content sensor and enter the following URL:

http://yourprtgserver.ip/api/getsensorsbystate.htm?name=downsens&username=xyz&password=abc

This URL will display the total number of sensors which are in Error state (red), shown as a number between brackets [].

[8]

Please note: If there is no sensor in error state, the brackets will only contain a whitespace:

[ ]

The HTTP Content sensor reads this information and uses it as sensor values. Now your can use limits and triggers to send notifications.

The possible values for the "name" parameter are:

You can only request one value per request/sensor. So in order to monitor unknown and error sensors you need to set up two HTTP Content sensors.

Please have a look at the API documentation for more information about using the HTTP API: How can I use the PRTG application programming interface (API)?

New Custom Sensor Available

What you basically want to do, is present a counter like the Gadget does. This routine is now implemented in a new Custom Sensor: SensorCount.

It requires the following parameters to query your PRTG server:

-s=ip-address[:portnumber] -u=username -p=password

Using (a combination of) the following switches you can count the sensors of your choice.

-u    count up sensors
-d    count down sensors
-a    count acknowledged down sensors
-w    count warning sensors
-u    count unusual sensors
-p    count paused sensors
-k    count unknown sensors

So in order to monitor unknown and error sensors you simply supply the -k and the -d switch.

This article applies to PRTG Network Monitor 13.2 or later

Monitoring the Number of Sensors in a Specific Status

In order to monitor the number of sensors in a specific status, for example, paused or unknown sensors count, add an HTTP XML/REST Value Sensor to your PRTG installation.

Set up the sensor as indicated below. This approach will retrieve an XML file via PRTG API containing the current number of all sensor states and parses it. Provide the XML node denoting the sensor status you are interested in and define sensor limits depending on your needs.

Steps to Go

1. Add an HTTP XML/REST Value sensor to your PRTG installation.

2. In the sensor settings, provide the following URL:

http://yourprtgserver/api/gettreenodestats.xml

Note: You'll need to add the username and passhash/password of your PRTG server to the URL in order to authenticate, as per the example below:

For details, please refer to PRTG Manual: HTTP API

3. Enter the XML node denoting the sensor status you are interested in. In order to monitor the number of paused sensors, use the parameter pausedsens. See below for other possible values.

4. You can leave all other settings unchanged.

5. Click Continue to create the sensor.

6. Define limits for warnings and alarms in the sensor’s channel settings.

You can use the following parameters for the XML node:

This sensor monitors now the number of sensors in the defined status and goes into warning or alarm status depending on the defined limits.