PRTG Manual: NetFlow v9 (Custom) Sensor

The NetFlow v9 (Custom) sensor receives traffic data from a NetFlow v9-compatible device and shows the traffic by type. With this sensor, you can define your own channel definitions to divide traffic into different channels.

i_round_redMake sure that the sensor matches the NetFlow version that your device exports.

NetFlow v9 (Custom) Sensor

NetFlow v9 (Custom) Sensor

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

Sensor in Other Languages

  • Dutch: NetFlow v9 (aangepast)
  • French: NetFlow v9 personnalisé
  • German: NetFlow v9 (Benutzerdefiniert)
  • Japanese: NetFlow v9(カスタム)
  • Portuguese: NetFlow v9 (customizado)
  • Russian: NetFlow v9 (настраиваемый)
  • Simplified Chinese: NetFlow v9 (自定义)
  • Spanish: NetFlow v9 (personalizado)

Remarks

  • This sensor has a very high performance impact. Use it with care. We recommend that you use no more than 50 sensors of this sensor type on each probe.
  • You must enable NetFlow export of the respective version on the target device for this sensor to work. The device must send the flow data stream to the IP address of the probe system.
  • This sensor does not officially support more than 50 channels. Depending on the data used with this sensor, you might exceed the maximum number of supported channels. In this case, PRTG tries to display all channels. Be aware, however, that you experience limited usability and performance.
  • You cannot use this sensor in cluster mode. You can only set it up on a local probe or a remote probe but not on a cluster probe.
  • This sensor only supports the IPv4 protocol.
  • See the Knowledge Base: What is the Active Flow Timeout in flow sensors?

i_podYou 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.

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. You can change nearly all settings on the sensor's Settings tab after creation.

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 name to identify the sensor.

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:

  • bandwidthsensor
  • netflowsensor

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).

NetFlow v9 Specific Settings

NetFlow v9 Specific Settings

NetFlow v9 Specific Settings

Setting

Description

Receive Packets on UDP Port

Enter the User Datagram Protocol (UDP) port number on which the flow packets are received. It must match the UDP port number in the NetFlow export options of the hardware router device. Enter an integer.

i_round_redWhen you configure the export, make sure that you select the appropriate NetFlow version for this sensor.

Sender IP Address

Enter the IP address of the sending device that you want to receive the NetFlow from. Enter an IP address to only receive data from a specific device or leave the field empty to receive data from any device on the specified port.

Receive Packets on IP Address

Select the IP addresses on which PRTG listens to NetFlow packets. The list of IP addresses is specific to your setup. To select an IP address, enable a check box in front of the respective line. The IP address that you select must match the IP address in the NetFlow export options of the hardware router device.

i_round_redWhen you configure the export, make sure that you select the appropriate NetFlow version for this sensor.

i_round_blueYou can also select all items or cancel the selection by using the check box in the table header.

Active Flow Timeout (Minutes)

Enter a time span in minutes after which the sensor must receive new flow data. If the timeout elapses and the sensor receives no new data during this time, it shows the Unknown status. Enter an integer. The maximum timeout is 60 minutes.

i_round_blueWe recommend that you set the timeout one minute longer than the timeout in the hardware router device.

i_round_redIf you set this value too low, flow information might be lost.

i_square_cyanFor more details, see the Knowledge Base: What is the Active Flow Timeout in flow sensors?

i_round_blueIf the target device sends incorrect time information that results in wrong monitoring data, try to use 0 as active flow timeout. This ignores the start and stop information of a flow as provided by the device and accounts all data to the current point in time. It might result in spikes but all data is captured.

Sampling Mode

Define if you want to use the sampling mode:

  • Off: Use the standard flow.
  • On: Use the sampling mode and specify the Sampling Rate below.

i_round_redThis setting must match the setting in the xFlow exporter.

Sampling Rate

This setting is only visible when sampling mode is On above. Enter a number that matches the sampling rate in your device that exports the flows. If the number is different, monitoring results will be incorrect. Enter an integer.

Channel Definition

Enter a channel definition to divide the traffic into different channels. Enter each definition in one line. The sensor accounts all traffic that you do not define a channel for to the default channel Other.

i_square_cyanFor detailed information, see section Channel Definitions for Flow, IPFIX, and Packet Sniffer Sensors.

i_round_redExtensive use of many filters can cause load problems on the probe system. We recommend that you define specific, well-chosen filters for the data that you really want to analyze. We recommend that you do not use more than 20 channels in graphs and tables, and not more than 100 channels in total. For performance reasons, we recommend that you add several sensors with fewer channels each.

Stream Data Handling

Define what PRTG does with the stream and packet data:

  • Discard stream data (recommended): Do not store the stream and packet data.
  • Store stream data only for the 'Other' channel: Only store stream and packet data that is not otherwise filtered and is therefore accounted to the default Other channel. PRTG stores this data in the \StreamLog subfolder of the PRTG data directory on the probe system. The file name is Streams Sensor [ID] (1).csv. This setting is for debugging purposes. PRTG overwrites this file with each scanning interval.
  • Store all stream data: Store all stream and packet data. This setting is for debugging purposes. PRTG overwrites this file with each scanning interval.

i_round_redUse with caution. If you enable this setting, it can create huge data files. We recommend that you only use this setting for a short time.

Filtering

i_square_cyanFor detailed information, see section Filter Rules.

Filtering

Filtering

Setting

Description

Include Filter

Define if you want to filter any traffic. If you leave this field empty, the sensor includes all traffic. To include specific traffic only, define filters using a special syntax.

Exclude Filter

First, the sensor considers the filters in Include Filter. From this subset, you can explicitly exclude traffic, using the same syntax.

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.

Primary Toplist

Primary Toplist

Primary Toplist

Setting

Description

Primary Toplist

Define which Toplist is the primary Toplist of the sensor:

  • Top Talkers
  • Top Connections
  • Top Protocols
  • [Any custom Toplists you add]

i_round_bluePRTG shows the primary Toplist in maps when you add a Toplist object.

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 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

Scanning Interval

Scanning Interval

i_square_cyanFor more information, see section Root Group Settings, section Scanning Interval.

Schedules, Dependencies, and Maintenance Window

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 Window

Schedules, Dependencies, and Maintenance Window

i_square_cyanFor more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

Access Rights

Access Rights

i_square_cyanFor more information, see section Root Group Settings, section Access Rights.

Channel Unit Configuration

Channel Unit Configuration

Channel Unit Configuration

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

Toplists

For all Flow (NetFlow, jFlow, sFlow, IPFIX) and Packet Sniffer sensors, Toplists are available on the sensor's Overview tab. Using Toplists, you can review traffic data for small time periods in great detail.

i_square_cyanFor more information, see section Toplists.

Filter Rules

The following filter rules apply to all Flow (NetFlow, jFlow, sFlow, IPFIX) and Packet Sniffer sensors.

i_square_cyanFor more information, see section Filter Rules for Flow, IPFIX, and Packet Sniffer Sensors.

Field

Possible Filter Values

IP

IP address or DNS name

Port

Any number

SourceIP

IP address or DNS name

SourcePort

Any number

DestinationIP

IP address or DNS name

DestinationPort

Any number

Protocol

Transmission Control Protocol (TCP), User Datagram Protocol (UDP), Internet Control Message Protocol (ICMP), Open Shortest Path First (OSPF), any number

ToS

Type of Service (ToS): any number

DSCP

Differentiated Services Code Point (DSCP): any number

The following filter rules apply to NetFlow v9 sensors only.

Field

Possible Filter Values

Interface

Any number

ASI

Any number

InboundInterface

Any number

OutboundInterface

Any number

SenderIP

IP address of the sending device. Use this if you have several devices that send flow data on the same port, and you want to divide the traffic of each device into a different channel.

Possible values: IP address or DNS name

SourceASI

Any number

DestinationASI

Any number

MAC

Physical address

SourceMAC

Physical address

DestinationMAC

Physical address

Mask

Mask values represent subnet masks in the form of a single number (number of contiguous bits).

DestinationMask

Mask values represent subnet masks in the form of a single number (number of contiguous bits).

NextHop

IP address or DNS name

VLAN

VLAN values represent a VLAN identifier (any number).

SourceVLAN

VLAN values represent a VLAN identifier (any number).

DestinationVLAN

VLAN values represent a VLAN identifier (any number).

Channel List

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

Channel

Description

[Custom]

The traffic by type according to the channel definition

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.

Other

All traffic for which no channel is defined in bytes per second

Total

The total traffic in bytes per second

i_round_blueThis channel is the primary channel by default.

More

i_square_blueKnowledge Base

What is the Active Flow Timeout in flow sensors?

What security features does PRTG include?

Where is the volume line in graphs?

 

i_toolsPAESSLER TOOLS

NetFlow Tester