<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: NetFlow v9 (Custom) Sensor

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.

It 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).

Receive NetFlow 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 that you configured in the NetFlow export options of your hardware router device. Enter an integer value.

When configuring export, make sure that you select the appropriate NetFlow version for this sensor.

Sender IP

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 NetFlow Packets on IP

Select the IP addresses on which PRTG listens to NetFlow packets. The list of IP addresses you see 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 all items or cancel the selection by using the check box in the table header.

The IP address you select here must match the one you have configured in the NetFlow export options of your hardware router device.

When configuring export, make sure that 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 was received during this time, the sensor changes to an Unknown status. Enter an integer value.

We recommend that you set the timeout one minute longer than the respective timeout configured in your hardware router device. The maximum timeout is 60 minutes.

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

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

If 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.

This setting must match the setting in the xFlow exporter.

Sampling Rate

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

Channel Definition

Enter a channel definition to divide the traffic into different channels. Write each definition in one line. All traffic for which no channel is defined is accounted to the default channel named Other.

For detailed information, see section Channel Definitions for xFlow, IPFIX, and Packet Sniffer Sensors.

Extensive use of many filters can cause load problems on the probe system. We recommend that you define specific, well-chosen filters for the data you really want to analyze.

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 \StreamLog subfolder of the PRTG data directory:

• 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.

Use 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.

Include Filter

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

For detailed information, see section Filter Rules.

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, see section Filter Rules.

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.

You 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 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.
  This option cannot be used in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This field 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

Define which Toplist is your primary Toplist:

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

The primary Toplist is shown in maps when adding a Toplist object.

Click 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 shows 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 shows 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 shows 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.

Sensors 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 does not apply to these sensors. All other options can apply.

If you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

If a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

You 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 settings here. They are 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.

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

Schedules are generally inherited. New schedules are added to schedules that you already set up, 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 selected object and all child objects are not monitored. They are in a Paused status instead. Choose between:

• Not set (monitor continuously): No maintenance window is set and monitoring is always 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 an active maintenance window.

To terminate an active 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 end 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 a different object. You can choose from:

• Use parent: Use the dependency type of the parent object.
• Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if a specific sensor is in a Down status or in a Paused status caused by another dependency.

• Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in a Down status, the device is 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 is paused if the parent group is paused by another dependency.

To 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 are paused. You can check all dependencies under Devices | Dependencies in 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 object 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 is additionally delayed by the defined time span. This can prevent false alarms, for example, after a server restart, by giving systems more time for all services to start up. Enter an integer value.

This 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.

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

User Group Access

Define the user groups that have access to the sensor. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:

• Inherited: Inherit the access rights settings of the parent object.
• No access: Users in this user group cannot see or edit the sensor. The sensor neither shows up in lists nor in the device tree.
• Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings.
• Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
• Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings.

For more details on access rights, see section Access Rights Management.

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

Channel Unit Types

For each type of 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

Custom channel types can be set on sensor level only.

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

Interface

Any number

ASI

Any number

InboundInterface

Any number

OutboundInterface

Any number

SenderIP

IP 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 (see Valid Data Formats)

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 (see Valid Data Formats)

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)