N-central Help

KBA10003: SNMP Service Troubleshooting

Knowledge Base Article #:


Applicable Versions:

N-central 6.x, 7.x, 8.x, 9.x

Date Created/Updated:

April 27, 2011


This article discusses how to find how many indices can be monitored, and how to troubleshoot SNMP services in N-central.

To start, you will need a utility to perform SNMP Queries. For this example we advise the use GetIF, which is free and available here. We must advise that this is a 3rd party software tool and N-able takes no responsibility for any negative impact this software may cause. Your discretion is advised.

Once installed, open GetIF and enter the IP of the device you are monitoring. If you are running getIF directly on the device itself, enter the local IP or

Please make sure that the read only community string listed in GetIF is the community string of the device you are trying to make a connection to.

The SysDescr field should populate if a connection is made and should describe the system. (Processor and Operating system).

Review DNS name and the system variable box beside the Start button for errors if a connection could not be made. The Read Community string will need to match the community string set on the device.

Please review your Operating System's manual or online FAQ to enable SNMP and set a Read Only Community string on the device in which you would like to monitor.

Click the MBrowser tab

Next, you'll need to paste the OID corresponding to the service you wish to monitor.

You will need to paste the OID in the second field from the top (which by default has .1 entered).

Once the OID is pasted in, (ensuring that it has the leading decimal), press enter. If the whole OID does not appear after pasting it, try again. It's not uncommon that this happens when using getIF.

After pressing enter, information should appear in the larger field below where you paste the OID.

If no values are returned, it means that the SNMP MIBS are not installed on the device and the OID you have entered does not extist. (For HP devices, these MIBS are installed as part of HP Insight Manager. For Dell devices, they're installed as part of the Dell OpenManage suite.)

If the software is installed but the SNMP values are still not being returned, and you are sure that you are querying the correct OID, then you will need to contact the device manufacturer to troubleshoot why the MIBS were not installed with the software.

Otherwise, each line returned represents an interface that was found, with a text description. This information shows the index as well.

For example, if we queried Dell fans, using the OID . - we may see:

  • .
  • .
  • .

This means there are 3 fans. Their indices are: 1.1, 1.2 and 1.3.

In N-central, we'll then create 3 instances of the Fan (Dell) service.

Under the Service Details for Fan (Dell), we would enter 1.1 for the Index Value field of one instance of the service, 1.2 in another instance of the service, and 1.3 in another instance. We will leave the "Name Variable" field blank.

After 15 - 20 minutes, the services should report a reading.