<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: SNMP Trap Receiver Sensor

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

It shows the following:

  • Overall number of received traps per second
  • Trap messages categorized as "warning" per second
  • Trap messages categorized as "error" per second
  • Number of dropped packets per second
  • The actual trap messages
SNMP Trap Receiver Sensor

SNMP Trap Receiver Sensor

Click here to enlarge: http://media.paessler.com/prtg-screenshots/snmp_trap_receiver.png

Remarks

  • With the available filter options, you can define individually which types of messages the sensor will consider for monitoring, and which messages it will categorize as warning or error messages. Depending on the filters, received messages are counted in the respective channels.
  • Add the sensor to the probe device to receive all messages of the system running the probe.
  • Add the sensor to a specific device to receive all messages from this device directly. This makes this sensor type faster than just using source filters.
  • You can use specific placeholders in email notification templates to see the messages when you receive an email notification. See the Knowledge Base: What placeholders can I use with PRTG?
  • Sensor states of this sensor type persist for one scanning interval only. If there is no warning or error message in the following scanning interval, the sensor will show an up status again. For a workaround, see this Knowledge Base article: How can I configure sensors using speed limits to keep the status for more than one interval?
  • If you do not add the sensor to a probe device but to another device in PRTG, be careful with the configuration: Ensure that the IP address or DNS name of the parent device matches the proper sender. For example, if you want to receive messages from a Storage Area Network (SAN), you might have to add a device to PRTG using 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.
  • This sensor type cannot be used in cluster mode. You can set it up on a local probe or remote probe only, not on a cluster probe.
  • For a general introduction to the receiver's configuration, please see manual section Monitoring Syslogs and SNMP Traps.
  • This sensor type can have a high impact on the performance of your monitoring system. Please use it with care! We recommend that you use no more than 50 sensors of this sensor type on each probe.

icon-prtg-on-demandYou cannot add this sensor type to cloud probes in PRTG in the cloud. If you want to use this sensor type, please add it to a remote probe device.

icon-prtg-on-demandPRTG in the cloud does not support the import of MIB files. The SNMP Trap Receiver sensor will only consider the MIBs that PRTG includes by default.

Add Sensor

The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.

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 where you created this sensor. See the Device Settings for details. For some sensor types, you can define the monitoring target explicitly in the sensor settings. Please 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.

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.

Priority

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

SNMP Trap Specific

Listen on Port

Enter the number of the port on which the sensor waits for SNMP traps. The default port is 162. Please enter an integer value. We recommend that you use the default value.

Purge Messages After

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

Filter

Include Filter

Define if you want to filter traps. If you leave this field empty or use the keyword "any", the sensor will process all data. This is the default setting. To include specific types of traps only, define filters using a special syntax. For more information, see section Filter Rules.

Exclude Filter

Define which types of traps the sensor will discard and not process. To exclude specific types of traps, define filters using a special syntax. For more information, see section Filter Rules.

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. For more information, see section Filter Rules.

icon-i-roundMessages are collected until a scanning interval ends. As long as the scanning interval is running, no status change will happen. By default, the sensor will turn into a Warning status after a scanning interval has finished and there was at least one warning message (and no error message) during this interval. The status will remain Warning at least until the succeeding scanning interval has finished. If the sensor did not receive any warning or error message in this scanning interval, its status will turn Up again after the 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. For more information, see section Filter Rules.

icon-i-roundMessages are collected until a scanning interval ends. As long as the scanning interval is running, no status change will happen. By default, the sensor will turn into a Down status after a scanning interval has finished and there was at least one error message during this interval. The status will remain Down at least until the succeeding scanning interval has finished. If the sensor did not receive any warning or error message in this scanning interval, its status will turn Up again after the interval.

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 will always be displayed below the sensor's name. The available options depend on what channels are available for this sensor.

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

Graph Type

Define how different channels will be shown for this sensor.

  • Show channels independently (default): Show an own 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 an easy-to-read 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 Channels Settings settings).

Stack Unit

This setting is only available if stacked graphs are selected above. Choose 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 following settings are inherited from objects 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. To change a setting only for this object, disable inheritance by clicking the check mark in front of the corresponding setting name. You will then see the options described below.

Scanning Interval

Scanning Interval

Select a scanning interval (seconds, minutes, or hours) from the list. The scanning interval determines the time 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 a sensor has time reach and check a device again in case a sensor query fails. The sensor can try to re-reach and check a device several times, depending on the option you select here, before it will be set to a Down status. This helps you avoid false alarms if the monitored device has only temporary issues. For previous scanning intervals with failed requests, the sensor will show a Warning status. Choose between:

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

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

icon-i-roundIf a sensor has defined error limits for channels, it will always show a Down status immediately, so no "wait" option will apply.
 

icon-i-roundIf a channel uses lookup values, it will always show a Down status immediately, so no "wait" options will apply.

Schedules, Dependencies, and Maintenance Window

icon-i-roundInheritance for schedules, dependencies, and maintenance windows cannot be interrupted. 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, hours) every week. With the period list option it is also possible to pause monitoring for a specific time span. You can create new schedules and edit existing ones in the account settings.

icon-i-roundSchedules are generally inherited. New schedules will be added to existing ones, 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" period, this object and all child objects will not be monitored. They will be in a paused state 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 field to a date in the past.

Maintenance Begins

This field is only visible if you enabled the 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 enabled the maintenance window above. Use the date time picker to enter the end date and time of the maintenance window.

Dependency Type

Define a dependency type. Dependencies can be used to pause monitoring for an object depending on the status of another. You can choose between:

  • Use parent: Pause the current sensor if the device, where it is created on, is in Down status, or is paused by another dependency.
  • Select object: Pause the current sensor if the device, where it is created on, is in Down status, or is paused by another dependency. Additionally, pause the current sensor if a specific other object in the device tree is in Down status, or is paused by another dependency. Select below.
  • Master object for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of the device, where it is created on: If the sensor is in 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 of its parent device is in Down status, or if it is paused by another dependency.

icon-i-roundTesting your dependencies is easy! Simply choose Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later all dependent objects should 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 the Select object option is enabled above. Click on the reading-glasses and use the object selector to choose an object on which the current sensor will depend.

Dependency Delay (Sec.)

Define a time span in seconds for a dependency delay. After the master object for this dependency goes back to Up status, PRTG will start monitoring the depending objects after this extra delayed. This can help to avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Please enter an integer value.

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

Access Rights

User Group Access

Define which user group(s) will have access to the object you're editing. 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, though not accessible.
  • 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 the object's settings. They cannot edit access rights settings.
  • Full: Users in this group can see the object, review its monitoring results, edit the object's 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.

For more details on access rights, please see the section User Access Rights.

Channel Unit Configuration

Channel Unit Types

For each type of sensor channel, define the unit in which data is displayed. If defined on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):

  • Bandwidth
  • Memory
  • Disk
  • File
  • Custom

icon-i-roundCustom channel types can be set on sensor level only.

Debugging

Log Data to Disk

Define if the probe will write a log file of the received data to the data folder (see Data Storage) to the disk for debugging purposes. Choose between:

  • Off (recommended): Do not write additional log files. Recommended for normal use cases.
  • On: Write log files for all data received.

icon-i-redUse with caution! When enabled, huge data files can be created. Please use for a short time and for debugging purposes only.

Filter Rules for Traps

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

field[filter]

 
You can use various filters suitable to your needs. Include and exclude filters define which traps to monitored. Warning and error filters define how to categorize received traps. Provide these filters in the sensor settings as formulas. Formulas are fields which 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[10.0.23.10/255]

agent[ip]

Enter an IP address which specifies the object that creates the SNMP trap. Only v1 is supported.

agent[10.0.0.1]

enterprise[oid]

Enter an OID which specifies the object that originates the trap. Only v1 is supported.

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"]

icon-i-roundIt is not necessary to use quotation marks (") to find strings, they will be internally removed.

bindings[oid,value]

Enter an OID and a substring to match a value in the given OID. Separate OID and value with a comma.

bindings[1.3.6.1.4.1.2.6.182.1.2.31.1.0,error]

gentrap[number]

Enter a number which specifies the generic trap type. Ranges are also possible.

gentrap[3], gentrap[2-6]

spectrap[number]

Enter a number which defines the specific trap code. Ranges are also possible.

spectrap[4], spectrap[0-3]

version[number]

Enter a number (1 or 2) which specifies the SNMP version.

version[1], version[2]

community[text]

Enter a community string for exact, case sensitive match.

community[public],
community[private]

Messages Tab: Review and Analyze Traps

PRTG stores received traps as common files in the data folder (see section Data Storage). To review and analyze all received messages, you can access the most recent data directly in a table list in the PRTG web interface. You can access this list via the Overview tab of the sensors.

icon-i-roundReceived traps are only shown after an (automatic) page refresh following to a sensor scan in the table on the Overview tab (default for auto refresh is 30 seconds).

For more details and further filter options, click the Messages tab of the SNMP Trap Receiver sensor. You will see all received messages in a table list. On 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 available in the sensor settings, but you can define them without using formulas. Provide the desired parameters and PRTG loads the filtered list automatically.

icon-i-roundYou can automatically add a filter by clicking the content of a column.

Advanced Filter Settings

You can open advanced filter settings with by clicking the gear icon in the Filter row. The Advanced Filter will appear in a popup window. In the text field, you can define a filter using the syntax as given in section Filter Rules for Traps. If you have provided filter parameters on the Messages tab, the advanced filter will already include 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.

More

Video Tutorial: How to Set Up an SNMP Trap Receiver Sensor in PRTG

Knowledge Base: How can I configure sensors using speed limits to keep the status for more than one interval?

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

Knowledge Base: What placeholders can I use with PRTG?

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

Edit Sensor Channels

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

Notifications

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

Others

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

Sensor Settings Overview

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

Keywords: