<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: sFlow (Custom) Sensor

The sFlow (Custom) sensor receives traffic data from an sFlow v5-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 target device supports sFlow v5.

i_round_blueThis sensor analyzes only header traffic.

sFlow (Custom) Sensor

sFlow (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: sFlow (Custom)
  • French: sFlow personnalisé
  • German: sFlow (Benutzerdef.)
  • Japanese: sFlow(カスタム)
  • Portuguese: sFlow (customizado)
  • Russian: sFlow (нестандартный)
  • Simplified Chinese: sFlow (自定义)
  • Spanish: sFlow (personalizado)


Consider the following remarks and requirements for this sensor:



Performance impact

  • 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 requires that the sFlow v5 export is enabled on the target system. The target system must send the flow data stream to the IP address of the probe system.

RAW data

  • This sensor accepts RAW data.


Cluster probe

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


  • This sensor only supports IPv4.


  • This sensor does not officially support more than 50 channels.

Knowledge Base

Hosted probe

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.


There are some limitations that you should consider before you use this sensor:

  • This sensor only supports sFlow v5 datagrams.
  • This sensor only supports IPv4 flows.
  • This sensor only supports the "raw packet header" format.
  • This sensor only supports the "Flow sample" and "Extended flow" formats. It cannot process "Counter" formats.
  • This sensor only processes samples where the source ID matches the ifIndex of the input interface (avoiding double-counted traffic) and ascending sequence numbers.
  • This sensor only supports sample packets of the Ethernet type "IP" (with optional VLAN tag)
  • This sensor only supports sampled packets of the types TCP and UDP.

i_toolsWe recommend that you use sFlow Tester for debugging.

Basic Sensor Settings

Basic Sensor Settings

Basic Sensor Settings

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

  • bandwidthsensor
  • sflowsensor

i_square_cyanFor more information about basic sensor settings, see section Sensor Settings.

sFlow v5 Specific Settings

sFlow v5 Specific Settings

sFlow v5 Specific Settings



Receive Packets on UDP Port

Enter the UDP port number on which the flow packets are received. It must match the UDP port number in the sFlow export options of the hardware router device. The default port is 6343. Enter an integer.

i_round_redWhen you configure the export, make sure that you select the appropriate sFlow v5 for this sensor

Sender IP Address

Enter the IP address of the sending device that you want to receive the sFlow 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 sFlow 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 sFlow export options of the hardware router device.

i_round_redWhen you configure the export, make sure that you select the appropriate sFlow v5 for this sensor

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

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 more 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. It can create huge data files. We recommend that you only use this setting for a short time.


i_square_cyanFor more information, see section Filter Rules.





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



Primary Channel

Select a channel from the list to define it as the primary channel. In the device tree, PRTG displays the last value of the primary channel 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 this sensor shows different channels:

  • 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 select Stack channels on top of each other above.

Select a unit from the list. PRTG stacks all channels with this unit 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



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.


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

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

Channel List

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




The traffic by type according to the channel definition


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


All traffic for which no channel is defined


The total traffic

i_round_blueThis channel is the primary channel by default.


i_square_blueKNOWLEDGE BASE

Where is the volume line in graphs?

What security features does PRTG include?



sFlow Tester