PRTG Manual: sFlow Sensor

The sFlow sensor receives traffic data from an sFlow V5-compatible device and shows the traffic by type. Only header traffic is analyzed. Make sure that the device matches the sFlow version V5. There are several filter options available to divide traffic into different channels.

The sensor can show the following traffic types in kbit per second:

  • Chat (Internet Relay Chat (IRC), AOL Instant Messenger (AIM))
  • Citrix
  • File Transfer Protocol (FTP)/Peer-to-Peer (P2P) (file transfer)
  • Infrastructure (network services: Dynamic Host Configuration Protocol (DHCP), Domain Name System (DNS), Ident, Internet Control Message Protocol (ICMP), Simple Network Management Protocol (SNMP))
  • Mail (mail traffic: Internet Message Access Protocol (IMAP), Post Office Protocol version 3 (POP3), Simple Mail Transfer Protocol (SMTP))
  • NetBIOS
  • Remote control (Remote Desktop Protocol (RDP), Secure Shell (SSH), Telnet, Virtual Network Computing (VNC))
  • WWW (web traffic: HTTP, HTTPS)
  • Total traffic
  • Other protocols (other User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) traffic)

icon-i-roundWhich channels the sensor actually shows might depend on the monitored device and the sensor setup.

sFlow Sensor

sFlow Sensor

Remarks

  • This sensor can have a high impact on the performance of your monitoring system. Use it with care. We recommend that you use no more than 50 sensors of this sensor type on each probe.
  • You must enable sFlow V5 export on the monitored device for this sensor to work. 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 probe or a remote probe).
  • This sensor accepts RAW data only. The stream must be sent via IPv4.
  • 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.
  • For cloning this sensor, the following rules apply. If you add the clone to the same probe, PRTG keeps the selected IP addresses on which it listens for xFlow (NetFlow, jFlow, sFlow, IPFIX) packets. If you add the clone to a different probe, PRTG selects all available IP addresses by default. You can change the selected IP addresses in the sensor settings.

icon-prtg-on-demandYou cannot add this sensor to the Hosted Probe of a PRTG hosted by Paessler instance. If you want to use this sensor, add it to a remote probe device.

Limitations of This Sensor

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

  • Only sFlow version 5 datagrams are supported
  • Only IPv4 flows are supported
  • Only the "raw packet header" format is supported
  • Only the "Flow sample" and "Extended flow" formats are supported. "Counter" formats cannot be processed
  • PRTG only processes samples where the source ID matches the ifIndex of the input interface (avoiding double-counted traffic) and ascending sequence numbers.
  • Sample packets have to be of the ethernet type "IP" (with optional VLAN tag)
  • Sampled packets of the types TCP and UDP are supported

icon-book-arrowsWe recommend that you use the sFlow tester for debugging. You can download it here: Paessler sFlow Tester

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 on which you created the sensor. See the Device Settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. 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.

There are default tags that are automatically predefined in a sensor's settings when you add a sensor. See section Default Tags below.

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.

icon-i-roundIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

Priority

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

Default Tags

bandwidthsensor, sflowsensor

sFlow Specific Settings

Receive sFlow Packets on UDP Port

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

icon-i-round-redWhen configuring the export, ensure that you select the appropriate sFlow version 5.

Sender IP

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 sFlow Packets on IP

Select the IP addresses on which PRTG listens to sFlow 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. You can also select and deselect all items by using the check box in the table header. The selected IP address must match the IP address that you configured in the sFlow export options of your hardware router device.

icon-i-round-redWhen configuring the export, ensure that you select the appropriate sFlow version 5.

Log Stream Data to Disk (for Debugging)

Define if you want the probe to write a logfile of the stream and packet data to the data folder (see Data Storage). Choose from:

  • None (recommended): Do not write additional logfiles. We recommended that you select this for normal use cases.
  • Only for the 'Other' channel: Only write logfiles of data that is not otherwise filtered and therefore accounted to the default Other channel.
  • All stream data: Write logfiles for all data received.

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

Channel Configuration

Channel Selection

Define the categories the sensor accounts the traffic to. There are different groups of traffic available. Choose from:

  • Web: Internet web traffic.
  • File Transfer: Traffic from FTP.
  • Mail: Internet mail traffic.
  • Chat: Traffic from chat and instant messaging.
  • Remote Control: Traffic from remote control applications, such as RDP, SSH, Telnet, and VNC.
  • Infrastructure: Traffic from network services, such as DHCP, DNS, Ident, ICMP, and SNMP.
  • NetBIOS: Traffic from NetBIOS communication.
  • Citrix: Traffic from Citrix applications.
  • Other Protocols: Traffic from various other protocols via UDP and TCP.

For each traffic group, you can select how many channels will be used for each group, that is, how detailed the sensor divides the traffic. For each group, choose from:

  • No (icon_channel_selection_no): Do not account traffic of this group in its own channel. All traffic of this group is accounted to the default channel named Other.
  • Yes (icon_channel_selection_yes): Count all traffic of this group and summarize it into one channel.
  • Detail (icon_channel_selection_detail): Count all traffic of this group and further divide it into different channels. The traffic appears in several channels as shown in the Content column.
    icon-i-redExtensive use of this option can cause load problems on your probe system. We recommend that you set specific, well-chosen filters for the data you really want to analyze.

icon-book-bulbYou can change the default configuration for groups and channels. For details, see the Knowledge Base: How can I change the default groups and channels for xFlow and Packet Sniffer sensors?

Filtering

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.

icon-book-arrowsFor detailed information, see section Filter Rules below.

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.

icon-book-arrowsFor detailed information, see section Filter Rules below.

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

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

Graph Type

Define how different channels will be 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 will generate a 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 Channel Settings settings).

Stack Unit

This field is only visible if you enable Stack channels on top of each other above. Select 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

Primary Toplist

Define which Toplist will be your primary Toplist. It will be shown in maps when adding a Toplist object. Choose from:

  • Top Talkers
  • Top Connections
  • Top Protocols
  • [Any custom Toplists you have added]

Inherited Settings

By default, all of the following settings are inherited from objects that are 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. For more information, see section Inheritance of Settings. To change a setting for this object only, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You will then see the options described below.

Scanning Interval

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

Scanning Interval

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

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

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

icon-i-roundIf you define error limits for a sensor's channels, the sensor will immediately show a Down status. No "wait" option will apply.

icon-i-roundIf a channel uses lookup values, the sensor will immediately show a Down status. No "wait" options will apply.

Schedules, Dependencies, and Maintenance Window

icon-i-roundYou cannot interrupt the inheritance for schedules, dependencies, and maintenance windows. 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 or hours) every week.

icon-book-arrowsYou can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Account Settings—Schedules.

icon-i-roundSchedules are generally inherited. New schedules will be added to existing schedules, 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, the current sensor and all child objects will not be monitored. They will be in a Paused status 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 to a date in the past.

Maintenance Begins

This field is only visible if you enable Set up a one-time 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 enable Set up a one-time maintenance window above. Use the date time picker to enter the start date and time of the maintenance window.

Dependency Type

Define a dependency type. You can use dependencies to pause monitoring for an object depending on the status of another object. You can choose from:

  • Use parent: Use the dependency type of the parent device.
  • Select a sensor: Use the dependency type of the parent device. Additionally, pause the current sensor if another specific sensor is in a Down status or in a Paused status caused by another dependency. Select below.
  • Master sensor for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of its parent device: If the sensor is in a 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 is paused by another dependency.

icon-i-roundTo test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects will 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 you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current sensor will depend.

Dependency Delay (Sec.)

This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay.

After the master sensor for this dependency comes back to an Up status, monitoring of the dependent 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. Enter an integer value.

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

Access Rights

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

User Group Access

Define the user groups that will have access to the selected object. 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 but it cannot be accessed.
  • 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 its settings. They cannot edit access rights settings.
  • Full: Users in this group can see the object, review its monitoring results, edit its 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.

icon-book-arrowsFor more details on access rights, see section User Access Rights.

Channel Unit Configuration

Click inherited_settings_button to interrupt the inheritance. See section Inheritance of Settings for more information.

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.

Toplists

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

icon-book-arrowsFor more information, see section Toplists.

Filter Rules

The following filter rules apply to all xFlow and Packet Sniffer sensors.

Field

Possible Filter Values

IP

IP address or Domain Name System (DNS) name (see Valid Data Formats)

Port

Any number

SourceIP

IP address or DNS name (see Valid Data Formats)

SourcePort

Any number

DestinationIP

IP address or DNS name (see Valid Data Formats)

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 sFlow sensors only.

Field

Possible Filter Values

Interface

Any number

InboundInterface

Any number

OutboundInterface

Any number

SenderIP

IP of the sending device. This is helpful if several devices send flow data on the same port, and you want to divide the traffic of each device into a different sensor channel.

Possible values: IP address or DNS name (see Valid Data Formats)

MAC

Physical address

SourceMAC

Physical address

DestinationMAC

Physical address

More

PRTG Manual:

Knowledge Base: How can I change the default groups and channels for xFlow and Packet Sniffer sensors?

Knowledge Base: Where is the volume line in graphs?

Paessler Website: sFlow Tester - Testing sFlow export configurations

Edit Sensor Channels

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

Notification Triggers

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

Others

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

Sensor Settings Overview

For information about sensor settings, see the following sections: