PRTG Manual: NetFlow V9 Sensor
The NetFlow V9 sensor receives traffic data from a NetFlow V9 compatible device and shows the traffic by type. Please make sure the sensor matches the NetFlow version your device is exporting! There are several filter options available to divide traffic into different channels.
Note: In order for the sensor to work, NetFlow export of the respective version must be enabled on the device. The device must send the flow data stream to the IP address of the PRTG probe system on which the sensor is set up (either a local or remote probe). 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 technology behind flow monitoring, please see Monitoring Bandwidth via Flows section.
The Add Sensor dialog appears when adding a new sensor on a device manually. It only shows the setting fields that are imperative for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change all settings in the sensor's Settings tab later.
On the sensor's details page, click on the Settings tab to change settings.
Note: If not set explicitly in a sensor's settings, it will connect to the IP Address or DNS Name defined in the settings of the parent device the sensor is created on.
Basic Sensor Settings |
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Sensor Name |
Enter a meaningful name to identify the sensor. The name will be shown by default in the device tree and in all alarms. |
Tags |
Enter one or more tags, separated by space or comma. You can use tags to group sensors and use tag-filtered views later on. Tags are not case sensitive. We recommend using the default value. You can add additional tags to it, if you like. Other tags are automatically inherited from objects further up in the device tree. Those are not visible here. |
Priority |
Select a priority for the sensor. This setting determines where the sensor will be placed in sensor lists. Top priority will be at the top of a list. You can choose from one star (low priority) to five stars (top priority). |
NetFlow Specific Settings |
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Receive NetFlow Packets on UDP Port |
Enter the UDP port number on which the flow packets are received. It must match the one you have configured in the NetFlow export options of your hardware router device. Please enter an integer value. Note: When configuring export, please make sure you select the appropriate NetFlow version for this sensor. |
Sender IP |
Enter the IP address of the sending device you want to receive the NetFlow from. Enter an IP address to receive data from a specific device only, or leave the field empty to receive data from any device on the specified port. |
Receive NetFlow Packets on IP |
Select the IP address(es) on which PRTG listens to NetFlow packets. The list of IP addresses shown here is specific to your setup. To select an IP address, add a check mark in front of the respective line. The IP address selected here must match the one configured in the NetFlow export options of your hardware router device. Note: When configuring export, please make sure you select the appropriate NetFlow version for this sensor. |
Active Flow Timeout (Minutes) |
Enter a time span in minutes after which new flow data must be received. If the timeout is reached and no new data is received, the sensor may switch to an Unknown status. Please enter an integer value. We recommend setting this one minute longer than the respective timeout configured in your hardware router device. Note: If you set this value too low, flow information might get lost! |
Sampling Mode |
Define if you want to use the sampling mode. This setting must accord to the setting in the flow exporter. Choose between:
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Sampling Rate |
This field is only visible when sampling mode is enabled above. Enter a number that matches the sampling rate in your exporter device. If the number is different, monitoring results will be incorrect. Please enter an integer value. |
Log Stream Data to Disk (for Debugging) |
Define if the probe will write a log file of the stream and packet data to the data folder (see Data Storage). Choose between:
Note: Use with caution! When enabled, huge data files can be created. Please use for a short time and for debugging purposes only. |
Channel Configuration |
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Channel Selection |
Define the categories the traffic will be accounted to. There are different groups of traffic available. Choose between:
For each traffic group, you can select how many channels will be used for each group, i.e. how detailed traffic will be divided. For each group, choose between:
Note: You can change the default configuration for groups and channels. For details, please see section More. |
Filtering |
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Include Filter |
Define if you want to filter any traffic. If you leave this field empty, all traffic will be included. To include specific traffic only, define filters using a special syntax. For detailed information, please see Filter Rules for xFlow, IPFIX, and Packet Sniffer Sensors section. |
Exclude Filter |
First, the filters defined in the Include Filter field are considered. From this subset, you can explicitly exclude traffic, using the same syntax. For detailed information, please see Filter Rules for xFlow, IPFIX, and Packet Sniffer Sensors section. |
Sensor Display |
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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 underneath the sensor's name. The available options depend on what channels are available for this sensor. Note: You can set another primary channel later by clicking on the pin symbol of a channel in the sensor's overview tab. |
Chart Type |
Define how different channels will be shown for this sensor.
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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. |
Primary Toplist |
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Primary Toplist |
Define which will be your primary toplist. It will be shown in maps when adding a toplist object. Choose from:
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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 for this object, disable inheritance by clicking on the check mark symbol in front of the respective setting name. You will then see the options described below.
Scanning Interval |
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Scanning Interval |
The scanning interval determines the time the sensor waits between two scans. Select a scanning interval (seconds, minutes, or hours) from the list. You can change the available intervals in the system administration. |
Schedules, Dependencies, and Maintenance Window |
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Note: Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted; the according settings from the parent objects will always be active. However, you can define additional settings here. They will be active in parallel to the parent objects' settings. |
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Schedule |
Select a schedule from the list. Schedules can be used to monitor for a certain time span (days, hours) throughout the 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. Note: Schedules are generally inherited. New schedules will be added to existing ones, so all schedules are active. |
Maintenance Window |
Specify if you want to set-up a one-time maintenance window. During a maintenance window this object and all child objects will not be monitored. They will enter a paused state then. Choose between:
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Maintenance Begins At |
This field is only visible if maintenance window is enabled above. Use the date time picker to enter the start date and time of the maintenance window. |
Maintenance End At |
This field is only visible if maintenance window is enabled 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:
Note: Testing 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. |
Dependency |
This field is only visible if the select object option is enabled above. Click on the reading-glass symbol and use the object selector to choose an object on which the current sensor will be dependent on. |
Delay (Seconds) |
Define a time span. After the master object for this dependency comes back to an Up status, monitoring of the depending 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. Please enter an integer value in seconds. Note: This setting is not available if you choose this sensor to be the Master object for parent. In this case, please define delays in the parent Device Settings or the superior Group Settings. |
Access Rights |
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User Group Access |
Define which user group(s) will have access to the object you're editing. A table with user groups and right is shown; it contains all user groups from your setup. For each user group you can choose from the following access rights:
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 about access rights, please see section User Access Rights. |
Channel Unit Configuration |
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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):
Note: Custom channel types can be set on sensor level only. |
For all flow and packet sniffer sensors there are Toplists available on the Overview tab of a sensor's detail page. Using toplists, you can review traffic data of small time periods in great detail. For more information, please see Toplists section.
Paessler Website: Paessler NetFlow Testers
Knowledge Base: How can I change the default groups and channels for xFlow and Packet Sniffer sensors?
In order to change display settings, spike filter, and limits, please switch to the sensor's Overview tab and click on the gear icon of a specific channel. For detailed information, please see Sensor Channels Settings section.
Click on the Notifications tab to change notification triggers. For detailed information, please see Sensor Notifications Settings section.
For more general information about settings, please see Object Settings section.
For information about sensor settings, please see the following sections:
- Sensor Settings
- List of Available Sensor Types
- Additional Sensor Types (Custom Sensors)
- Sensor Channels Settings
- Sensor Notifications Settings
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