PRTG Manual: SNMP Library Sensor
The SNMP Library sensor uses a compiled Management Information Base (MIB) file to create sensors that monitor a device via the Simple Network Management Protocol (SNMP). This approach provides custom monitoring beyond the standard SNMP sensors of PRTG.
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 came back from the target device based on checking every object identifier (OID) in the MIB file. From this list, you can select what you want to monitor.
The SNMP Library sensor automatically creates the following custom SNMP sensors based on the data types available in the MIB file:
Sensor |
Description |
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For all OIDs that return single values |
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For all OIDs that return string values |
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For all OIDs that return tables |
The SNMP Library sensor is not actually a sensor and does not appear as a running sensor. It is a sensor that uses the meta-scan facility of the probe to find or match OIDs from the compiled MIB file and makes the creation of custom sensors easier because you do not have to manually enter the OIDs.
To monitor SNMP-capable devices and add sensors using 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 already contain the OIDs of SNMP counters for the most common devices in a network.
For more information, see the Knowledge Base: How do SNMP, MIBs and OIDs work?
- 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
- 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, contact the Paessler support team.
Manually add a new sensor to an SNMP device. From the Add Sensor dialog, select SNMP Library sensor. PRTG shows a list of .oidlib files that are available on the system. This list contains all library files stored in the \snmplibs subfolder of the PRTG program directory. It contains both the ones delivered with PRTG and your own files.
The file names in the list indicate the respective purpose. Select a name that appears suitable for your device (for example, choose an MIB file that you imported before) and confirm via OK. Often, the Paessler common oid library.oidlib is a good start.
If the file does not fit to your 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 file.
The SNMP Library sensor takes a list of OIDs that you imported from an MIB file into an .oidlib file and tests the OIDs against a device to find the OIDs the device supports. This discovery process is the meta-scan. If counters are found for your device, the sensor settings open with a list of available monitoring items that you can select. PRTG sorts the list in advance to make the related values sequential in the list.
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 function 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 desired counters and click Save. PRTG now creates sensors based on the OID types of the selected entries.
- For selected SNMP single values, PRTG creates SNMP Custom Advanced sensors with 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.
- If you select OIDs that return string values, PRTG creates one SNMP Custom String sensor for each selected entry that returns a string value.
- For selected SNMP table entries, PRTG creates SNMP Custom Table sensors with up to 10 channels for 10 columns per row.
Once a custom SNMP sensor has been created, you can create a device template from it and prepare it for distribution. For example, you can refine the template with better name templates.
Default .oidlib Files Overview
The following files are included in PRTG and allow the extension of your SNMP monitoring to many devices. Note that the libraries might not support all devices and/or parameters.
.oidlib File |
Description |
---|---|
APC UPS.oidlib |
Can be used to monitor uninterruptible power supplies (UPSs) from APC American Power Conversion Corp. |
APCSensorstationlib.oidlib |
Can be used to monitor alarm status, communication status, humidity, and temperature as shown by an APC sensor station. |
Basic Linux Library (UCD-SNMP-MIB).oidlib |
Can be used to monitor basic system parameters on Linux systems, such as memory, disk and swap, CPU, and more. |
cisco-interfaces.oidlib |
Can be used to monitor 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 |
Can be used to monitor 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 |
Can be used to monitor Dell storage devices. Possible parameters include disk arrays, battery and power supply, fan and temperature, virtual disk, and more. |
Dell Systems Management Instrumentation.oidlib |
Can be used to monitor 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 |
Can be used to monitor toner, paper, and jam status of an HP LaserJet printer. |
Linux SNMP (AX BGP DisMan EtherLike Host).oidlib |
Can be used to monitor different aspects of Linux systems.
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Linux SNMP (Framework Proxy Noti v2).oidlib |
Can be used to monitor different aspects of Linux systems.
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Linux SNMP (IP Net SNMP Noti OSPF RMON SMUX).oidlib |
Can be used to monitor different aspects of Linux systems.
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Linux SNMP (Source TCP UCD UDP).oidlib |
Can be used to monitor different aspects of Linux systems.
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Paessler Common OID Library.oidlib |
Can be used to monitor many common hardware devices. It is used for several sensors and is encrypted. |
SNMP Informant std.oidlib |
Can be used to monitor logical disks, processor, memory, and network interface on Windows systems. |
Additionally, you can create your own .oidlib files by importing your device manufacturers' MIB files with the free MIB Importer tool. You can convert your MIB files and save the resulting .oidlib files to the \snmplibs subfolder of the PRTG program directory.
For more information about the MIB Importer and to download this tool, see the Knowledge Base: How can I import my MIB files into PRTG?
If your imported .oidlib file contains lookups (you can see this in section Lookup in the MIB Importer), you can define your own sensor states for returning values. Add an SNMP Library sensor using this .oidlib file. PRTG then creates a lookup definition file using the lookupname of the chosen library as id parameter.
Note: The lookups are added without state definitions, so the sensor shows the Warning status by default. You have to edit the corresponding lookup files to get reliable alarms. Override the lookup definition with your own custom lookup as described in section Define Lookups.
To import MIB files into PRTG Hosted Monitor, contact the Paessler support team.
The following settings in the Add Sensor dialog differ in comparison to the sensor's Settings tab.
SNMP Library Specific
Setting |
Description |
---|---|
Library |
Shows the path to the .oidlib file selected before. This setting is for your information only. You cannot change it. |
Library OIDs |
Select the parameters of the device that you want to monitor. A list specific to your setup is shown. It contains all counters found in the chosen library that match your device. Select one or more items by adding a check mark 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. Use the search box to narrow down to your desired items. Depending on the kind of the selected entries, PRTG creates the following sensors:
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Click the Settings tab of a sensor to change its settings.
Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.
Setting |
Description |
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Sensor Name |
Enter a meaningful 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.
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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.
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
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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 ( |
The available sensor settings depend on the sensor that the SNMP Library sensor created. For details about settings, see the sections of these sensors:
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.
|
Graph Type |
Define how different channels are shown for this sensor:
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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. |
By default, all of the following settings are inherited from objects that are higher in the hierarchy. You should 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. You then see the options described below.
For more information, see section Inheritance of Settings.
Click to interrupt the inheritance.
Setting |
Description |
---|---|
Scanning Interval |
Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:
|
If a Sensor Query Fails |
Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows the Warning status. Choose from:
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Schedules, Dependencies, and Maintenance Windows
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.
Setting |
Description |
---|---|
Schedule |
Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:
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Maintenance Window |
Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:
|
Maintenance Begins |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the one-time maintenance window. |
Maintenance Ends |
This setting is only visible if you enable Set up a one-time maintenance window above. Use the date time picker to enter the end date and time of the one-time maintenance window. |
Dependency Type |
Select a dependency type. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:
|
Dependency |
This setting is only visible if you enable Select a sensor above. Click |
Dependency Delay (Sec.) |
This setting is only visible if you enable Select a sensor above. Define a time span in seconds for the dependency delay. After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. Enter an integer value.
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Click to interrupt the inheritance.
Setting |
Description |
---|---|
User Group Access |
Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:
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KNOWLEDGE BASE
How do SNMP, MIBs, and OIDs work?
How can I import my MIB files into PRTG?
Can't find a sensor for my device in PRTG but I believe it supports SNMP. How to proceed?
What security features does PRTG include?
What SNMP sensors does PRTG offer?
My SNMP sensors don't work. What can I do?
How can I monitor EMC Isilon storage systems with PRTG?
PAESSLER TOOLS
MIB Importer
For more information about sensor settings, see the following sections: