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 will determine which data types are available for monitoring. When you create the sensor, it will provide 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 will automatically create the following custom SNMP sensors based on the data types available in the MIB file:

icon-i-roundThe SNMP Library sensor is not actually a sensor and will not appear as a running sensor. It is a sensor that uses the meta-scan facility of the PRTG probe to find or match OIDs from the compiled MIB file and eases the creation of custom sensors 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.

icon-book-bulbFor more information, see the Knowledge Base: How do SNMP, MIBs and OIDs work?

SNMP Custom Advanced Sensor Created by SNMP Library

SNMP Custom Advanced Sensor Created by SNMP Library

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

Add Sensor

Manually add a new sensor to an SNMP device. From the Add Sensor dialog, select SNMP Library sensor. PRTG will show a list of .oidlib files that are available on the system. This list contains all library files stored at the \snmplibs folder of your PRTG server installation directory—both the ones delivered with PRTG and your own files.

List of SNMP Library Files

List of SNMP Library 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.

icon-i-blueIf the file does not fit to your device, this will result 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 adding the sensor with another 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 will 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.

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

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

List of SNMP Table Values: Sorted by MIB, Category (Table Name/OID), Row, 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 and makes it easier for you to select 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 will now create sensors based on the OID types of the selected entries.

  • For selected SNMP single values, PRTG will create SNMP Custom Advanced sensors with up to 10 channels for 10 OIDs each. For example, 22 selected single values will 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 will create SNMP Custom Table sensors with up to 10 channels for 10 columns per row.

icon-i-roundOnce 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 not all devices and/or parameters may be supported by the libraries.

.OIDLIB FILE

DESCRIPTION

APC UPS.oidlib

Can be used to monitor uninterruptible power supplies (UPS) 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.

icon-i-roundThis file may detect a very large number of interfaces. It may take a few seconds until the selection table is shown.

Linux SNMP (Framework Proxy Noti v2).oidlib

Can be used to monitor different aspects of Linux systems.

icon-i-roundThis file may detect a very large number of interfaces. It may take a few seconds until the selection table is shown.

Linux SNMP (IP Net SNMP Noti OSPF RMON SMUX).oidlib

Can be used to monitor different aspects of Linux systems.

icon-i-roundThis file may detect a very large number of interfaces. It may take a few seconds until the selection table is shown.

Linux SNMP (Source TCP UCD UDP).oidlib

Can be used to monitor different aspects of Linux systems.

icon-i-roundThis file may detect a very large number of interfaces. It may take a few seconds until the selection table is shown

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.

Import MIB Files

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

icon-book-arrowsFor details about directory paths, see section Data Storage.

icon-book-bulbFor more information about the MIB Importer and to download this tool, see the Knowledge Base: How can I import my MIB files into PRTG?

icon-toolsIf 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 will then create a lookup definition file using the lookupname of the chosen library as id parameter.

Note: The lookups will be added without state definitions, so the sensor will show a 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—Customizing Lookups.

icon-prtg-on-demandPRTG hosted by Paessler does not support the import of MIB files. You can use the SNMP Library sensor only with the default .oidlib files in PRTG hosted by Paessler.

SNMP Library Sensor—Add Sensor Settings

The following settings in the Add Sensor dialog differ in comparison to the sensor's Settings tab.

SNMP Library Specific

Library

Shows the path to the .oidlib file selected before. This setting is shown for your information only and cannot be changed here.

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 and deselect all items 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 will create the following sensors:

Sensor Settings

On the details page of a sensor, click the Settings tab to change its settings.

icon-i-roundUsually, 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.

Basic Sensor Settings

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.

Parent Tags

Shows Tags that this sensor inherits from its parent device, group, and probe. This setting is shown for your information only and cannot be changed here.

Tags

Enter one or more Tags, separated by spaces or commas. You can use tags to group sensors and use tag–filtered views later on. Tags are not case sensitive. We recommend that you use the default value.

There are default tags that are automatically predefined in a sensor's settings when you add a sensor. See section Default Tags below.

You can add additional tags to the sensor if you like. Other tags are automatically inherited from objects further up in the device tree. These are visible above as Parent Tags.

icon-i-roundIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

Priority

Select a priority for the sensor. This setting determines where the sensor is placed in sensor lists. A sensor with a top priority is at the top of a list. Choose from one star (low priority) to five stars (top priority).

Default Tags

snmplibrarysensor

Sensor Specific

icon-book-arrowsThe available sensor settings depend on the sensor that the SNMP Library sensor created. For details about settings, see the sections of these sensors:

Sensor Display

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.

icon-i-roundYou can set a different primary channel later by clicking the pin symbol of a channel on the sensor's Overview tab.

Graph Type

Define how different channels will be 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 will generate a graph that visualizes the different components of your total traffic.
    icon-i-roundThis option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channel Settings settings).

Stack Unit

This field is only visible if you enable Stack channels on top of each other above. Select a unit from the list. All channels with this unit will be 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 the following settings are inherited from objects that are higher in the hierarchy and should be changed there if necessary. Often, best practice is to change them centrally in the Root group's settings. For more information, see section Inheritance of Settings. To change a setting for this object only, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You will then see the options described below.

Scanning Interval

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

Scanning Interval

Select a scanning interval (seconds, minutes, or hours). The scanning interval determines the amount of time that the sensor waits between two scans. You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Define the number of scanning intervals that the sensor has time to reach and check a device again in case a sensor query fails. Depending on the option that you select, the sensor can try to reach and check a device again several times before the sensor will show a Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor will show a Warning status. Choose from:

  • Set sensor to down immediately: Set the sensor to a Down status immediately after the first failed request.
  • Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to a Warning status after the first failed request. If the following request also fails, the sensor will show an error.
  • Set sensor to warning for 2 intervals, then set to down: Set the sensor to a Down status only after three consecutively failed requests.
  • Set sensor to warning for 3 intervals, then set to down: Set the sensor to a Down status only after four consecutively failed requests.
  • Set sensor to warning for 4 intervals, then set to down: Set the sensor to a Down status only after five consecutively failed requests.
  • Set sensor to warning for 5 intervals, then set to down: Set the sensor to a Down status only after six consecutively failed requests.

icon-i-roundSensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show a Down status. It is not possible to immediately set a WMI sensor to a Down status, so the first option will not apply to these sensors. All other options can apply.

icon-i-roundIf you define error limits for a sensor's channels, the sensor will immediately show a Down status. No "wait" option will apply.

icon-i-roundIf a channel uses lookup values, the sensor will immediately show a Down status. No "wait" options will apply.

Schedules, Dependencies, and Maintenance Window

icon-i-roundYou cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. The corresponding settings from the parent objects will always be active. However, you can define additional settings here. They will be active at the same time as the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days or hours) every week.

icon-book-arrowsYou can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Account Settings—Schedules.

icon-i-roundSchedules are generally inherited. New schedules will be added to existing schedules, so all schedules are active at the same time.

Maintenance Window

Specify if you want to set up a one-time maintenance window. During a maintenance window, the current sensor and all child objects will not be monitored. They will be in a Paused status instead. Choose between:

  • Not set (monitor continuously): No maintenance window will be set and monitoring will always be active.
  • Set up a one-time maintenance window: Pause monitoring within a maintenance window. You can define a time span for a monitoring pause below and change it even for a currently running maintenance window.

icon-i-roundTo terminate a current maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

Maintenance Begins

This field 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 maintenance window.

Maintenance Ends

This field 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 maintenance window.

Dependency Type

Define a dependency type. You can use dependencies to pause monitoring for an object depending on the status of another object. You can choose from:

  • Use parent: Use the dependency type of the parent device.
  • Select a sensor: Use the dependency type of the parent device. Additionally, pause the current sensor if another specific sensor is in a Down status or in a Paused status caused by another dependency. Select below.
  • Master sensor for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of its parent device: If the sensor is in a Down status, the device will be paused. For example, it is a good idea to make a Ping sensor the master object for its parent device to pause monitoring for all other sensors on the device in case the device cannot even be pinged. Additionally, the sensor will be paused if the parent group is paused by another dependency.

icon-i-roundTo test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects will be paused. You can check all dependencies in your PRTG installation by selecting Devices | Dependencies from the main menu bar.

Dependency

This field is only visible if you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current sensor will depend.

Dependency Delay (Sec.)

This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay.

After the master sensor for this dependency comes back to an Up status, monitoring of the dependent objects will be additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Enter an integer value.

icon-i-round-redThis setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, define delays in the parent Device Settings or in its parent Group Settings.

Access Rights

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

User Group Access

Define the user groups that will have access to the selected object. A table with user groups and types of access rights is shown. It contains all user groups from your setup. For each user group, you can choose from the following access rights:

  • Inherited: Use the access rights settings of the parent object.
  • None: Users in this group cannot see or edit the object. The object neither shows up in lists nor in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree but it cannot be accessed.
  • Read: Users in this group can see the object and review its monitoring results.
  • Write: Users in this group can see the object, review its monitoring results, and edit its settings. They cannot edit access rights settings.
  • Full: Users in this group can see the object, review its monitoring results, edit its settings, and edit access rights settings.

You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option.

icon-book-arrowsFor more details on access rights, see section User Access Rights.

More

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

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

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

Knowledge Base: How can I monitor EMC Isilon storage systems with PRTG?

Knowledge Base: What SNMP sensors does PRTG offer?

Knowledge Base: My SNMP sensors don't work. What can I do?

Edit Sensor Channels

To change display settings, spike filtering, and limits, switch to the sensor's Overview tab and click the gear icon of a specific channel. For detailed information, see section Sensor Channel Settings.

Notification Triggers

Click the Notification Triggers tab to change notification triggers. For detailed information, see section Sensor Notification Triggers Settings.

Others

For more general information about settings, see section Object Settings.

Sensor Settings Overview

For information about sensor settings, see the following sections: