Device and Sensor Setup > Sensor Settings

PRTG Manual: SNMP Trap Receiver Sensor

The SNMP Trap Receiver sensor receives and analyzes Simple Network Management Protocol (SNMP) traps.

The sensor can also show the actual trap messages.

SNMP Trap Receiver Sensor

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

Sensor in Other Languages

Dutch: SNMP Trap-ontvanger
French: Récepteur de Trap (SNMP)
German: SNMP-Trap-Empfänger
Japanese: SNMP トラップレシーバー
Portuguese: Receptor de trap SNMP
Russian: Приемник ловушек SNMP
Simplified Chinese: SNMP 陷阱接收程序
Spanish: Receptor de trap SNMP

Remarks

This sensor has a very high performance impact. We recommend that you use no more than 50 of this sensor on each probe.

This sensor does not support SNMP v3 traps. Use SNMP v1 or v2c.

This sensor only supports the User Datagram Protocol (UDP).

Add this sensor to the probe device to receive all messages of the remote probe system.

Add this sensor to a specific device to directly receive all messages from this device. This is faster than using source filters.

This sensor supports IPv6.

You can use placeholders in email notification templates to see messages when you receive email notifications.

The sensor states of this sensor persist for one scanning interval only. After showing the Warning or the Down status, and if there is no warning or error message in the next scanning interval, the sensor shows the Up status again. For a workaround, see the Knowledge Base: How can I configure sensors using speed limits to keep the status for more than one interval?

You can use the filter options to define which types of messages the sensor considers for monitoring, and which messages it categorizes as warnings or errors.

If you add the sensor to a device other than a probe device, the IP address or Domain Name System (DNS) name of the parent device must match the proper sender. For example, if you want to receive messages from a storage area network (SAN), you might need to add a device with the IP address of a specific array member that sends the messages. Providing a DNS name that points to the IP address of a whole group might not work for SANs.

In PRTG Network Monitor, you can copy the Management Information Base (MIB) file for your traps to the \MIB subfolder of the PRTG program directory to translate the object identifiers (OID) for the traps into readable messages. For more information, see the Knowledge Base: How can I show the name of a received OID in PRTG?

This sensor does not support cluster probes. You can only set it up on local probes or remote probes.

Knowledge Base: How do I test an SNMP Trap Receiver sensor?

You cannot add this sensor to the hosted probe of a PRTG Hosted Monitor instance. If you want to use this sensor, add it to a remote probe device.

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

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	The 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: snmptrapsensor
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 ().

SNMP Trap Specific

Setting	Description
Port	Enter the number of the port on which the sensor listens for SNMP traps. The default port is 162. Enter an integer. We recommend that you use the default value.
Purge Messages After	Define for how long PRTG stores received trap messages for analysis. Choose a period of time from the dropdown list.

Setting

Description

Port

Enter the number of the port on which the sensor listens for SNMP traps. The default port is 162. Enter an integer.

We recommend that you use the default value.

Purge Messages After

Define for how long PRTG stores received trap messages for analysis. Choose a period of time from the dropdown list.

Filter

For detailed information, see section Filter Rules.

Filter

Setting	Description
Include Filter	Define if you want to filter traps. If you leave this field empty or use the keyword any, the sensor processes all data. To include only specific types of traps, define filters using a special syntax.
Exclude Filter	Define which types of traps the sensor discards and does not process. To exclude specific types of traps, define filters using a special syntax.
Warning Filter	Define which types of traps count for the Warnings channel. To categorize received traps as warning messages, define filters using a special syntax. The sensor collects messages until a scanning interval ends. As long as the scanning interval is running, no status change happens. By default, the sensor changes to the Warning status after a scanning interval finishes and there was at least one warning message (and no error message) during this scanning interval. The sensor shows the Warning status at least until the succeeding scanning interval finishes. If the sensor does not receive any warning or error message in this scanning interval, its status changes to the Up status again with the start of the next scanning interval.
Error Filter	Define which types of traps count for the Errors channel. To categorize received traps as error messages, define filters using a special syntax. The sensor collects messages until a scanning interval ends. As long as the scanning interval is running, no status change happens. By default, the sensor changes to the Down status after a scanning interval finishes and there was at least one error message during this scanning interval. The sensor shows the Down status at least until the succeeding scanning interval finishes. If the sensor does not receive any warning or error message in this scanning interval, its status changes to the Up status again with the start of the next scanning interval.

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 select Stack channels on top of each other above. 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 select Stack channels on top of each other above.

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.

Channel Unit Configuration

Which channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.

Channel Unit Configuration

For more information, see section Root Group Settings, section Channel Unit Configuration.

Debug Options

Setting	Description
Result Handling	Define what PRTG does with the sensor result: Discard result (recommended): Do not store the sensor result. Store result: Store the last sensor result in the \Logs\debug subfolder of the PRTG data directory on the probe system. The file name is Sensor [ID]_[Date].log. This setting is for debugging purposes. Use with caution. We recommend that you only use this setting for a short time because it can create huge data files.

Setting

Description

Result Handling

Define what PRTG does with the sensor result:

Discard result (recommended): Do not store the sensor result.

Store result: Store the last sensor result in the \Logs\debug subfolder of the PRTG data directory on the probe system. The file name is Sensor [ID]_[Date].log. This setting is for debugging purposes.
Use with caution. We recommend that you only use this setting for a short time because it can create huge data files.

Filter Rules

Filter rules are used for the include, exclude, warning, and error definition fields of the SNMP Trap Receiver sensor. They are based on the following format:

field[filter]

You can use include and exclude filters to define which traps to monitor or use warning and error filters to define how to categorize received traps. Provide these filters in the sensor settings as formulas. Formulas are fields that you can combine with boolean operators (AND, OR, NOT) and brackets.

Field	Parameter	Examples
source[ip]	Enter an IP address where the UDPs come from. IP masks and ranges are also possible.	source[10.0.23.50], source[10.0.23.10-50], source[10.0.23.10/24]
agent[ip]	Enter an IP address that specifies the object that creates the SNMP trap. agent[ip] only supports v1.	agent[10.0.0.1]
enterprise[oid]	Enter an OID that specifies the object that originates the trap. enterprise[oid] only supports v1.	enterprise[1.3.6.1.4.1.2.6.182.1.2.31.1.0]
bindings[text]	Enter a substring to match all OIDs and values in the bindings.	bindings[ERROR], bindings[1.3.6.1.4.1.2.6.182.1.2.31.1.0], bindings["port blocked"] It is not necessary to use quotation marks (") to find strings. If the string contains quotation marks that you want to include in the filter, you need to escape them with quotation marks.
bindings[oid,value]	Enter an OID and a substring to match a value in the specified OID. Separate the OID and the value with a comma.	bindings[1.3.6.1.4.1.2.6.182.1.2.31.1.0,error]
bindings[oid,value,mode]	Enter an OID, a substring, and a mode to match a value in the specified OID. Separate the OID, the value, and the mode with a comma. The mode can be: substring (default): This mode works like bindings[oid,value]. exact: This mode enforces an exact match of a value. equal, greater, greaterorequal, less, or lessorequal: This interprets and compares values as numbers. This mode only supports integers without extra characters and without thousands separators. It also supports hex format.	bindings[1.3.6.1.4.1.2.6.182.1.2.31.1.0,error,exact] bindings[1.3.6.1.4.1.2.6.182.1.2.31.1.0,10,equal]
gentrap[number]	Enter a number that specifies the generic trap type. You can also enter ranges.	gentrap[3], gentrap[2-6]
spectrap[number]	Enter a number that defines the specific trap code. You can also enter ranges.	spectrap[4], spectrap[0-3]
version[number]	Enter a number (1 or 2) that specifies the SNMP version.	version[1], version[2]
community[text]	Enter a community string for an exact, case-sensitive match.	community[public], community[private]

Messages Tab: Review and Analyze Traps

PRTG stores received traps as common files in the \Trap Database subfolder of the PRTG data directory. To review and analyze all received messages, you can directly access the most recent data in a table list in the PRTG web interface. You can access this list via the sensor's Overview tab.

PRTG only shows received traps in the table on the Overview tab after an (automatic) page refresh following a sensor scan. The default value for auto refresh is 30 seconds.

For more details and further filter options, click the Messages tab of the SNMP Trap Receiver sensor. You see all received messages in a table list. At the top, you have display filter options to drill down into the data for specific events of your interest. The filters are the same as those that are available in the sensor settings, but you can define them without using formulas. Provide the desired parameters and PRTG automatically loads the filtered list.

PRTG automatically applies boolean operators to the filters in the following manner: parameters across all columns are combined with AND, and parameters within a single column are combined with OR.

The parameters that you enter in the filters must exactly match the parameters in the message. They are case sensitive.

You can automatically add a filter by clicking the content of a column.

Advanced Filter Settings

You can open advanced filter settings by clicking in the Filter row. The Advanced Filter appears in a popup window. In the text field, you can define a filter using the syntax as described in section Filter Rules.

If you provided filter parameters on the Messages tab, the advanced filter already includes them as a corresponding formula with the correct syntax. You can adjust this filter to your needs. You can also copy the automatically created and manually adjusted formula for usage in the filter fields of the sensor settings.

Channel List

Which channels the sensor actually shows might depend on the target 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
Drops	The number of dropped packets on the SNMP trap collector port This channel has a default limit Upper warning limit: 0.00000001
Errors	The number of messages categorized as "error" This channel has a default limit Upper error limit: 0.00000001
Messages	The overall number of received traps This channel is the primary channel by default.
Warnings	The number of messages categorized as "warning" This channel has a default limit Upper warning limit: 0.00000001