Knowledge Base

How to find out OIDs for Custom SNMP sensors

Out of the box, PRTG Traffic Grapher and IPCheck Server Monitor offer various sensors defined within the various provided libraries. However, sometimes these included libraries do not suffice and it is necessary to access devices by directly providing Object Identifiers (OIDs).

However, OIDs are generally not openly available in the documentation provided by hardware manufacturers. The manufacturers offer so-called MIB files which contain the information to create OIDs.

Using Paessler's MIB Import Tool you can import and convert MIB files, but sometimes the MIB files can't be loaded (the standards for MIB files are often interpreted in various ways which results in incompatible files).

If you can't convert your MIB file there is one other option to discern these OIDs to be used by PRTG Traffic Grapher and IPCheck Server Monitor.

Using GetIf to discern OIDs

GetIf is a handy little tool that can be used to ascertain and discern OIDs which, in turn, can be used to access custom sensor information. Setting up GetIf is quick and simple. Simply download the data files from www.wtcs.org/snmp4tpc/getif.htm, execute the Setup routine and GetIf will automatically install itself on your machine.

Then, start the program from the GetIf program group (Start | Programs | GetIf). You will need to enter the IP address for the server upon which you would like to look up the OIDs. You will also need to define various SNMP parameters (such as the Read / Write community strings).

In order to then access the OIDs, click on the "MBrowser" tab. If all was set up properly, you will notice boxes which, upon clicking on them, will open into a tree structure. At the bottom left, you will notice a number - this number is the OID. The further you go in the tree structure, the longer the number should get, as the individual nodes are being added to the OID value.

Find the device you are wanting to use in PRTG Traffic Grapher or IPChec Server Monitor and use the OID value presented by GetIf in order to set up a custom sensor - in this manner you can configure your own devices which might not be accessible directly from the provided libraries.

Note: Please note that this works only if the MIBs files (the description files for OID trees) for your device are already coming with GetIF. Please refer to the documentation to use your own MIB files.

Setting up "Custom" sensors in PRTG Traffic Grapher

Once you have the necessary OIDs, you can go and use these values to set up custom sensors in PRTG. Setting up custom sensors in PRTG Traffic Grapher is easy, once you have the necessary OID values.

First, select to add a new sensor by pressing the "Add Sensor" button in the top-left corner of PRTG Traffic Grapher. Follow the setup wizard's instructions and, when asked which type of sensor you would like to set up, select "SNMP Custom Sensor". On the next screen, enter a name for the device, the IP address / DNS name for the server upon which the device is to be found, the SNMP community string, as well as the SNMP port. On the next screen, you will be asked to enter an OID. Please enter the number ascertained above (or any applicable OID) and press "Test this OID" - a value should be returned.

If everything went smoothly, select "Next" and continue to set up the sensor, as desired. Once you are finished, the sensor should automatically generate a graph and start graphing.

Keep in mind that many sensor values are already included in the accompanying Paessler libraries - not every sensor that you configure requires you to set up a custom sensor and input a respective OID. Also notice that you can install the additional Paessler SNMP Helper library, in order to increase available devices.

We hope you enjoy working with PRTG Traffic Grapher!

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