PRTG Manual: SNMP Custom Table Sensor

The SNMP Custom Table sensor monitors entries from a table that is provided via the Simple Network Management Protocol (SNMP). You can create one new sensor per table row. For each sensor, you can define up to ten channels. Each channel shows the value of one defined table column.

i_round_blueThe SNMP Library sensor automatically creates SNMP Custom Table sensors when the Management Information Base (MIB) file that you import contains tables.

i_square_cyanFor a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

SNMP Custom Table Sensor

SNMP Custom Table Sensor

Sensor in Other Languages

  • Dutch: SNMP Aangepaste Tabel
  • French: Table SNMP personnalisée
  • German: SNMP (Benutzerdef. Tabelle)
  • Japanese: SNMP カスタムテーブル
  • Portuguese: Tabela customizada do SNMP
  • Russian: Нестандартная таблица SNMP
  • Simplified Chinese: SNMP 自定义表
  • Spanish: Tabla de SNMP personalizado

Remarks

  • It might not work to query data from a probe device via SNMP (querying localhost, 127.0.0.1, or ::1). Add this device to PRTG with the IP address that it has in your network and create the SNMP sensor on this device instead.
  • This sensor supports the IPv6 protocol.
  • This sensor has a low performance impact.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. Therefore, you do not see all settings in this dialog. You can change nearly all settings on the sensor's Settings tab after creation.

i_round_blueThe settings that you select in the Add Sensor dialog are valid for all sensors that you create when you finish the dialog.

SNMP Table

Setting

Description

Table OID

Enter the object identifier (OID) of the SNMP table that you want to monitor. The OID must directly point to an object that represents an SNMP table. PRTG creates one SNMP Custom Table sensor for each table row that you select.

i_round_blueIf you do not enter an OID, you cannot proceed with channel creation.

Basic Sensor Settings

Setting

Description

Sensor Name

Enter a meaningful name to identify the sensor. You can use the placeholders [tablename] and [rowidentifier]. PRTG replaces them with the name of the table and the identifying value of the chosen row respectively. You can select the column that provides the row identifier in the Identification Column option below.

You can also enter a valid OID that is part of a different SNMP table, for example, [1.3.6.1.2.1.2.2.1.2], to query information that the current table does not contain. PRTG adds the same index as in the original table to the OID.

Table Specific

Setting

Description

Table

The sensor shows you the table that the OID returns. Select the table rows that contain the data that you want to monitor. PRTG creates one sensor for each table row that you select.

i_round_blueEnable check boxes in front of the respective lines to select the items. Use the check box in the table header to select all items or to cancel the selection. In large tables, use the search function in the upper-right corner.

Identification Column

Define the identification column for the sensors that you want to create. The sensors use this column to uniquely identify each table row.

i_round_blueWe recommend that you use a unique identification column because it allows the sensors to keep track of changing indexes.

i_round_blueThe value of the column that you select as identification column replaces the [rowidentifier] in the sensor name. This lets you distinguish sensors that you create for the same SNMP table.

Channel #2 - #10

You can create up to 10 different channels for this sensor. You have to define at least one data channel, so you already see all available settings for Channel #1. Additionally, you can define Channel #2 up to Channel #10. To do so, choose between:

  • Disable: Do not create this channel.
  • Enable: Create this channel. Define further settings below.

i_round_blueIt is not possible to enable or disable channels after sensor creation.

i_round_blueAll channels that you define during the creation of an SNMP Custom Table sensor are the same for all sensors for each table row.

Value Type

Select the expected numeric type of the results at the OID:

  • Absolute (unsigned integer): Integer values without an operational sign, such as 10 or 120.
  • Absolute (signed integer): Integer values with an operational sign, such as -12 or 120.
  • Absolute (float): Float values, such as -5.80 or 8.23.
  • Delta (counter): Counter values. PRTG calculates the difference between the last and the current value. PRTG additionally divides the delta value by a time period to indicate a speed value.
    i_round_redThis mode only works if the difference between the last and the current value is positive and increases with each scanning interval. This mode does not support negative values and decreasing values.

i_round_redAbsolute (float) and Delta (counter) are not compatible with the unit Lookup.

i_round_blueSee below for other channel settings that you can also change after sensor creation.

i_round_redThis sensor monitors numeric values only. Make sure that you do not select columns that return strings because they lead to the Down status. For example, if you monitor an ifTable, we recommend that you do not select an ifDescr column because this results in an error.

Basic Sensor Settings

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

Basic Sensor Settings

Basic Sensor Settings

Setting

Description

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.

i_round_blueIf 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.

i_round_blueThis 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.

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

i_round_blueFor 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:

  • snmpcustomsensor
  • snmpcustomtable

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 (i_priority_1) to the highest priority (i_priority_5).

i_round_blueUsually, 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.

SNMP Table

SNMP Table

SNMP Table

Setting

Description

Table OID

Shows the OID of the SNMP table that this sensor monitors.

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

Table Specific

Table Specific

Table Specific

Setting

Description

Identifier

This is the value of the column that you selected as the Identification Column during sensor creation. PRTG also displays it in the sensor name to distinguish it from other sensors you created for the same table with other table rows. You can change the identifier if you want to.

Identification Column

Shows the table column that you chose as identification column.

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

Channel #x Name

Enter a name for the channel in which the sensor shows the desired result. Enter a string.

Channel #x Column

Select the table column that, together with the table row, points to the value that you want to monitor in this channel. You can choose between the available columns of the table that you monitor.

Channel #x Value Type

Shows the value type of the data that this sensor receives in this channel.

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

Channel #x Unit

Define the unit of the data that this sensor receives in this channel:

  • BytesBandwidth
  • BytesMemory
  • BytesDisk
  • Temperature
  • Percent
  • TimeResponse
  • TimeSeconds
  • TimeHours
  • Count
  • CPU
  • BytesFile
  • SpeedDisk
  • SpeedNet
  • Custom
  • Lookup

i_square_cyanFor more information about the available units, see section Custom Sensors.

i_round_blueTo use lookups with this channel, select Lookup and define the lookup file in Channel #x Lookup. Do not use Custom if you use lookups with this sensor.

i_round_redYou cannot use the unit Lookup if you select the value type Delta (counter) or Absolute (float). You are not able to create the sensor in this case.

Channel #x Custom Unit

This setting is only visible if you select the channel unit Custom above. Define a unit for the channel value. Enter a string.

Channel #x Lookup

This setting is only visible if you select the channel unit Lookup above. Select a lookup file that you want to use with this channel.

Channel #2 - #10

Shows if you enabled or disabled a channel.

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

Sensor Display

Sensor Display

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.

i_round_blueYou can set a different primary channel later by clicking b_channel_primary 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.
    i_round_redYou 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 the following 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 b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Scanning Interval

Click b_inherited_enabled to interrupt the inheritance.

Scanning Interval

Scanning Interval

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:

  • 30 seconds
  • 60 seconds
  • 5 minutes
  • 10 minutes
  • 15 minutes
  • 30 minutes
  • 1 hour
  • 4 hours
  • 6 hours
  • 12 hours
  • 24 hours

i_round_blueYou can change the available intervals in the system administration of PRTG Network Monitor.

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:

  • Set sensor to down immediately: Set the sensor to the Down status immediately after the first request fails.
  • Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to the Warning status after the first request fails. If the second request also fails, the sensor shows the Down status.
  • Set sensor to warning for 2 intervals, then set to down: Set the sensor to the Down status only after the third request fails.
  • Set sensor to warning for 3 intervals, then set to down: Set the sensor to the Down status only after the fourth request fails.
  • Set sensor to warning for 4 intervals, then set to down: Set the sensor to the Down status only after the fifth request fails.
  • Set sensor to warning for 5 intervals, then set to down: Set the sensor to the Down status only after the sixth request fails.

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

i_round_blueIf you define error limits for a sensor's channels, the sensor immediately shows the Down status. None of the interval options apply.

i_round_blueIf a channel uses lookup values, the sensor immediately shows the Down status. None of the interval options apply.

Schedules, Dependencies, and Maintenance Windows

i_round_blueYou 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 Windows

Schedules, Dependencies, and Maintenance Windows

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:

  • None
  • Saturdays
  • Sundays
  • Weekdays
  • Weekdays Eight-To-Eight (08:00 - 20:00)
  • Weekdays Nights (17:00 - 09:00)
  • Weekdays Nights (20:00 - 08:00)
  • Weekdays Nine-To-Five (09:00 - 17:00)
  • Weekends

i_round_blueYou can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Schedules.

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:

  • Do not set up a one-time maintenance window: Do not set up a one-time maintenance window. Monitoring is always active.
  • Set up a one-time maintenance window: Set up a one-time maintenance window and pause monitoring. You can define a time span for the pause below.

i_round_blueTo terminate an active maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

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:

  • Use parent: Use the dependency type of the parent object.
  • Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if a specific sensor is in the Down status or in the Paused status because of another dependency.
  • Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in the Down status, the device is 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 is paused if the parent group is paused by another dependency.

i_round_blueTo 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 are paused. You can check all dependencies under Devices | Dependencies in the main menu bar.

Dependency

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

Dependency Delay (Sec.)

This setting is only visible if you select 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.

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 b_inherited_enabled to interrupt the inheritance.

Access Rights

Access Rights

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:

  • Inherited: Inherit the access rights settings of the parent object.
  • No access: Users in this user group cannot see or edit the sensor. The sensor neither shows up in lists nor in the device tree.
  • Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings.
  • Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
  • Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings.

i_square_cyanFor more details on access rights, see section Access Rights Management.

Channel List

i_round_blueWhich channels the sensor actually shows might depend on the monitored device, the available components, and the sensor setup.

Channel

Description

Downtime

In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status in percent.

[Value]

The numeric values in up to 10 channels per table row

More

i_square_blueKNOWLEDGE BASE

How do I find out which OID I need for an SNMP Custom sensor?

What can I monitor with the SNMP Custom Table sensor?

What security features does PRTG include?

What SNMP sensors does PRTG offer?

My SNMP sensors don’t work. What can I do?

Can I monitor UPS systems complying with the UPS MIB (RFC-1628) with PRTG?

Sensor Settings Overview

For more information about sensor settings, see the following sections: