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Can't find a sensor for my device in PRTG but I believe it supports SNMP. How to proceed?



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I have a device that supposedly supports SNMP, I've been through the Available Sensor Types but couldn't find a sensor that matches my device name/model.

Is there a way to monitor the device? Do I need to use custom sensors? Do you have any further recommendations on how to monitor it?

mib oidlib prtg snmp snmplibrary

Created on Aug 5, 2015 1:52:10 PM by  Luciano Lingnau [Paessler Support]

Last change on Aug 12, 2015 4:47:46 AM by  Felix Saure [Paessler Support]

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This article applies to PRTG Network Monitor 15 or later

Custom Monitoring of Devices via SNMP

This is a guide to "Monitor your device" if it supports SNMP. It provides the instructions on adding a new SNMP Library sensor by importing an SNMP MIB file. As an example, we use the MIB of Synology, but the approach applies to almost all MIBs and systems.

Note: PRTG already comes with built-in sensors for logical disks, physical disks, and a system health sensor for Synology NAS systems.

Step 1: Confirm Device's SNMP support

1.1 Begin by confirming that your device supports the SNMP protocol. Check within the vendor's website, or within the device's configuration. SNMP is a standard protocol and most enterprise-grade devices offer SNMP support to some extent. But in any case we recommend that you double-check.

1.2 Enable SNMP on the target device. For SNMP versions v1 and v2c it is usually sufficient to set an SNMP Community String, bu some devices have more complex configurations (allowed managers, etc). Usually the public string is used. This is also the default community string that PRTG will query.

See also this article for basic requirements for SNMP.


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1.3 If the device does indeed support SNMP and you enabled it, test the functionality with our SNMP Tester. The "Read Device Uptime" is a great start. This test must yield a valid response (not 0). Fore a more sophisticated test, a Walk of 1.3.6 will confirm all OID's that the device can reply to. Please check the SNMP Tester Manual for more details.

Step 2: Download/Acquire the SNMP MIB

2.1 For some devices this will be the easy step, in others it will be the hard step. The SNMP MIB is the file that contains the definition for all OIDs that the device can reply to. It will define what a value is, what name describes that value, and so on. Here are some places to find the SNMP MIB file for your device:

  • Within the web interface of the target device
  • On a default location on the file system of the device
  • On the website of the device vendor
  • You might have to contact the vendor's support to get the MIB.

2.2 The MIB could be provided as a zip-file or as individual downloads. It is important to move/de-compress all the MIB files into a single folder (when more than one) so that when importing them any MIB dependencies can also be resolved.

Step 3: Importing the obtained MIB File

3.1 The import process is necessary because it converts the MIB that is written in Abstract Syntax Notation to a more performance-friendly format that PRTG understands. Fore more details about the Paessler MIB Importer please check its manual page.

3.2 Importing the extracted MIB files by selecting File | Import MIB File | Select File(s) from the main menu of the Paessler MIB Importer Version 3.4.8. The importer will display statistics related to the number of imported OIDs and errors (if any). import_message_thumb

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3.3 (optional) It is possible to edit/rename properties from the imported MIB files prior to using the file within PRTG. This way the name of the sensor or channel can be updated to a more friendly/useful description if required.
Note: In this step it is possible to review the channel's lookup in the description field. In this case such information is required to write a lookup definition (see step 4.4). import_rename_lookup_thumb

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3.4 (optional) It is also possible to use the Partial Selection to only include the OIDs that you need in the final oidlib file. This improves the performance when adding a new SNMP Library sensor and creates less visual clutter to select the required OIDs for monitoring. import_partial_selection_thumb

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3.5 Save the resulting oidlib to any location and copy it to the following program directory on the PRTG core server system:

\PRTG Network Monitor\snmplibs\

You will see the files in this folder when you add a new SNMP Library Sensor.

Step 4: Adding the Sensor(s) within PRTG

4.1 Once you have completed the steps above, add a new device to PRTG that points to the target device you want to monitor. You have to provide a name and IP/DNS address. During the creation you may also provide the SNMP credentials that the sensors of this device will use. You can change this also later.

4.2 On the previously created device, click Add Sensor, select the SNMP Library sensor from the list, and add it. Select the name of the file previously copied into PRTG from the list and select OK.

PRTG now performs a metascan to check which of the OIDs contained in the oidlib file are available on the monitored device. From the list you can then select for which properties you want to create a sensor: add_library_metascan_thumb

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If at this points PRTG hangs or takes a long time to perform the metascan please review this article.

Select the required properties (or all) and click Continue. After a few seconds your PRTG looks like this: add_library_sensor_thumb

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4.3 (optional) You can now configure limits for the created sensor channels. If you create a device template, these settings are also stored in the device template. PRTG will use them on devices discovered using that template.

4.4 Some sensors will display odd values, for example, the status 1 for a hard disk status. Define lookups in this case: You can define lookups so that PRTG understands the meaning of "0", "1", "2", or any other value for that sensor. Once you created/imported a lookup and configured it, the sensor will report the status correctly as in the screenshot below: add_library_lookupconfigured_thumb

Click for Full Size Image

There's a more detailed lookups guide available on a separate KB-post (link below):

For more details, please review the PRTG user manual or contact our support team.

Other related resources

Do you want to monitor an SNMP Table? Please review the following:

How to map a value to a status or message? Please check this guide:

PRTG Hangs or fails while adding Library Sensors? Please review:

Best Regards,
Luciano Lingnau [Paessler Support]

Created on Aug 5, 2015 2:03:13 PM by  Luciano Lingnau [Paessler Support]

Last change on Aug 3, 2016 7:51:50 AM by  Luciano Lingnau [Paessler Support]

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Disclaimer: The information in the Paessler Knowledge Base comes without warranty of any kind. Use at your own risk. Before applying any instructions please exercise proper system administrator housekeeping. You must make sure that a proper backup of all your data is available.