Device and Sensor Setup > Sensor Settings

PRTG Manual: SNMP Library Sensor

The SNMP Library sensor uses a Management Information Base (MIB) file to create sensors that monitor a device via the Simple Network Management Protocol (SNMP).

The content of the MIB file determines which data types are available for monitoring. When you create the sensor, it provides a list of counters that the target device returns based on every object identifier (OID) in the MIB file.

The SNMP Library sensor does not appear as a running sensor. It uses the meta-scan facility of the probe to find or to match OIDs from the MIB file. It is useful because you do not need to manually enter OIDs.

To monitor SNMP-capable devices and to add sensors via the SNMP Library sensor, download the manufacturer's MIB files for the target device, convert the MIB files to the OID library format, and import them into PRTG. PRTG also provides precompiled .oidlib files that contain the OIDs of SNMP counters for the most common network devices.

For more information, see the Knowledge Base: How do SNMP, MIBs and OIDs work?

SNMP Custom Advanced Sensor Created by SNMP Library Sensor

Sensor in Other Languages

▪Dutch: SNMP Bibliotheek

▪French: Bibliothèque (SNMP)

▪German: SNMP-Bibliothek

▪Japanese: SNMP ライブラリ

▪Portuguese: Biblioteca (SNMP)

▪Russian: Библиотека SNMP

▪Simplified Chinese: SNMP 库

▪Spanish: Biblioteca (SNMP)

Remarks

▪This sensor supports the IPv6 protocol.

▪This sensor has a very low performance impact.

▪See the Knowledge Base: How do SNMP, MIBs and OIDs work?

▪See the Knowledge Base: How can I import my MIB files into PRTG?

▪See the Knowledge Base: Can't find a sensor for my device in PRTG but I believe it supports SNMP. How to proceed?

To import MIB files into PRTG Hosted Monitor, see section Manage a PRTG Hosted Monitor Subscription.

Add Sensor

PRTG shows a list of .oidlib files that are available on the system. This list contains all library files in the \snmplibs subfolder of the PRTG program directory. It contains both the default PRTG library files and your own library files.

List of SNMP Library Files

The library file names in the list indicate their purpose. Select a library file that is suitable for the target device (for example, choose an MIB file that you imported) and confirm via Ok.

If the library file not suitable for the target device, this results in the error message The scan for available monitoring items has failed on this device: No such object (SNMP error # 222). If you see this message, click Cancel and try to add the sensor with a different library file.

The SNMP Library sensor takes a list of OIDs that you import from an MIB file into an .oidlib file and tests the OIDs against the target device to find the OIDs that the target device supports. This discovery process is the meta-scan. If the sensor finds counters for the target device, the sensor settings open with a list of all available monitoring items.

List of SNMP Single Values: Sorted by MIB, Category, Name

List of SNMP Table Values: Sorted by MIB, Category (Table Name/OID), Row, Name

The list of SNMP table values sequentially presents row values to help you find the values you are interested in.

You can also use the search to find the desired group or category. The search matches individual strings, so if your string has a space in it, put the search string in quotes.

Select the counters that you want to monitor and click Save. PRTG creates sensors based on the OID types of the selected counters.

Add Sensor Settings

Setting	Description
Library	Shows the path to the .oidlib file that this sensor uses. PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.
Category	Select the parameters that you want to monitor. The list is specific to your setup. The list contains all counters that are available in the .oidlib file that match the target device. Select one or more items by enabling or disabling the check boxes in front of the respective line. You can also select all items or cancel the selection by using the check box in the table header. Depending on the type of the selected entries, PRTG creates the following sensors: ▪SNMP Custom Advanced sensor: For up to 10 channels for 10 OIDs each. For example, 22 selected single values result in 3 sensors: 2 sensors with 10 channels and 1 sensor with 2 channels. ▪SNMP Custom String sensor: For each selected entry that returns a string value. ▪SNMP Custom Table sensor: For up to 10 channels for 10 columns per row. The channels represent the values in the columns of the same row. Once you create a custom SNMP sensor, you can create a device template from it and prepare it for distribution. For example, you can refine the template with better name templates.

Setting

Description

Library

Shows the path to the .oidlib file that this sensor uses.

PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Category

Select the parameters that you want to monitor. The list is specific to your setup. The list contains all counters that are available in the .oidlib file that match the target device. Select one or more items by enabling or disabling the check boxes in front of the respective line.

You can also select all items or cancel the selection by using the check box in the table header.

Depending on the type of the selected entries, PRTG creates the following sensors:

▪SNMP Custom Advanced sensor: For up to 10 channels for 10 OIDs each. For example, 22 selected single values result in 3 sensors: 2 sensors with 10 channels and 1 sensor with 2 channels.

▪SNMP Custom String sensor: For each selected entry that returns a string value.

▪SNMP Custom Table sensor: For up to 10 channels for 10 columns per row. The channels represent the values in the columns of the same row.

Once you create a custom SNMP sensor, you can create a device template from it and prepare it for distribution. For example, you can refine the template with better name templates.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Basic Sensor Settings

Setting	Description
Sensor Name	Enter a name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets. If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?
Parent Tags	Shows tags that the sensor inherits from its parent device, parent group, and parent probe. This setting is for your information only. You cannot change it.
Tags	Enter one or more tags. Confirm each tag with the Spacebar key, a comma, or the Enter key. You can use tags to group objects and use tag-filtered views later on. Tags are not case-sensitive. Tags are automatically inherited. It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>). For performance reasons, it can take some minutes until you can filter for new tags that you added. The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor: ▪snmplibrarysensor
Priority	Select a priority for the sensor. This setting determines the position of the sensor in lists. The highest priority is at the top of a list. Choose from the lowest priority () to the highest priority ().

Usually, a sensor connects to the IP Address/DNS Name of the parent device. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings.

Sensor Specific

The available sensor settings depend on the sensor that the SNMP Library sensor creates. For details about settings, see the sections of these sensors:

▪SNMP Custom Advanced sensor

▪SNMP Custom String sensor

▪SNMP Custom Table sensor

Sensor Display

Setting	Description
Primary Channel	Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor. You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.
Graph Type	Define how different channels are shown for this sensor: ▪Show channels independently (default): Show a graph for each channel. ▪Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic. You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).
Stack Unit	This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Setting

Description

Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, the last value of the primary channel is always displayed below the sensor's name. The available options depend on what channels are available for this sensor.

You can set a different primary channel later by clicking below a channel gauge on the sensor's Overview tab.

Graph Type

Define how different channels are shown for this sensor:

▪Show channels independently (default): Show a graph for each channel.

▪Stack channels on top of each other: Stack channels on top of each other to create a multi-channel graph. This generates a graph that visualizes the different components of your total traffic.
You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This setting is only visible if you enable Stack channels on top of each other as Graph Type. Select a unit from the list. All channels with this unit are stacked on top of each other. By default, you cannot exclude single channels from stacking if they use the selected unit. However, there is an advanced procedure to do so.

Inherited Settings

By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click under the corresponding setting name to disable the inheritance and to display its options.

For more information, see section Inheritance of Settings.

Scanning Interval

For more information, see section Root Group Settings, section Scanning Interval.

Schedules, Dependencies, and Maintenance Window

You cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects are always active. However, you can define additional schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.

Schedules, Dependencies, and Maintenance Window

For more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

For more information, see section Root Group Settings, section Access Rights.

Import MIB Files

Additionally, you can create your own .oidlib files by importing the device manufacturers' MIB files with the free MIB Importer tool. You can convert your MIB files and save the .oidlib file results to the \snmplibs subfolder of the PRTG program directory.

For more information about the MIB Importer, see the Knowledge Base: How can I import my MIB files into PRTG?

If the.oidlib files that you import contain lookups (you can see this in section Lookup in the MIB Importer), you can define your own sensor states for the values that the lookups return. Add an SNMP Library sensor with this .oidlib file. PRTG then creates a lookup definition file using the lookupname of the chosen library as id parameter.

PRTG adds the lookups without status definitions, so the sensor shows the Warning status by default. You must edit the corresponding lookup files to get reliable alarms. Override the lookup definition with your own custom lookup. For more information, see section Define Lookups.

To import MIB files into PRTG Hosted Monitor, see section Manage a PRTG Hosted Monitor Subscription.

Default .oidlib Files Overview

PRTG comes with the following .oidlib files.

The .oidlib files might not support all devices or parameters.

.oidlib File	Description
APC UPS.oidlib	Monitors uninterruptible power supplies (UPSs) from APC American Power Conversion Corp.
APCSensorstationlib.oidlib	Monitors alarm status, communication status, humidity, and temperature as shown by an APC sensor station.
Basic Linux Library (UCD-SNMP-MIB).oidlib	Monitors basic system parameters on Linux systems, such as memory, disk and swap, CPU, and more.
cisco-interfaces.oidlib	Monitors Cisco-specific parameters, for example, the number of present network interfaces on a system, several states of an interface (admin, oper, speed, type, errors, discards, etc.), and more.
cisco-queue.oidlib	Monitors queues on a Cisco interface, for example, queue depth and its maximum, discarded messages from the queue, the number of the queue within the queue set, and more.
Dell Storage Management.oidlib	Monitors Dell storage devices. Possible parameters include disk arrays, battery and power supply, fan and temperature, virtual disk, and more.
Dell Systems Management Instrumentation.oidlib	Monitors the hardware of Dell systems. Possible parameters include ACPower and battery, alerts, base board, BIOS, Baseboard Management Controller (BMC), chassis, COO, cooling, event log, firmware, integrated development environment (IDE), keyboard, memory, port, network, processor, Small Computer System Interface (SCSI), system, temperature, USB, universally unique identifier (UUID), and more.
HP LaserJet Status.oidlib	Monitors toner, paper, and jam status of an HP LaserJet printer.
Linux SNMP (AX BGP DisMan EtherLike Host).oidlib	Monitors different aspects of Linux systems. This file might detect a very large number of interfaces. It might take a few seconds until the selection table appears.
Linux SNMP (Framework Proxy Noti v2).oidlib	Monitors different aspects of Linux systems. This file might detect a very large number of interfaces. It might take a few seconds until the selection table appears.
Linux SNMP (IP Net SNMP Noti OSPF RMON SMUX).oidlib	Monitors different aspects of Linux systems. This file might detect a very large number of interfaces. It might take a few seconds until the selection table appears.
Linux SNMP (Source TCP UCD UDP).oidlib	Monitors different aspects of Linux systems. This file might detect a very large number of interfaces. It might take a few seconds until the selection table appears.
Paessler Common OID Library.oidlib	Monitors many common hardware devices. It is used for several sensors and is encrypted.
SNMP Informant std.oidlib	Monitors logical disks, processor, memory, and network interface on Windows systems.