PRTG Manual: Packet Sniffer Sensor

The Packet Sniffer sensor monitors the headers of data packets that pass a local network card using a built-in packet sniffer. You can choose from predefined channels. The sensor analyzes only header traffic.

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-round-blueWhich channels the sensor actually shows might depend on the monitored device and the sensor setup.

Packet Sniffer Sensor

Packet Sniffer Sensor

Sensor in Other Languages

  • Dutch: Packet Sniffer
  • French: Packet sniffing
  • German: Packet Sniffer
  • Japanese: パケットスニファー
  • Portuguese: Sniffer de pacotes
  • Russian: Анализатор пакетов
  • Simplified Chinese: 数据包嗅探程序
  • Spanish: Examen de paquetes

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.
  • By default, this sensor works only on a probe device.
  • This sensor supports the IPv6 protocol.
  • Using Network Mapper (Nmap) on the parent probe system might cause high CPU load. If you have this issue, restarting the PRTG probe service might help.
  • See the Knowledge Base: How can I change the default groups and channels for xFlow and Packet Sniffer sensors?

icon-i-round-blueBy default, you can only monitor traffic passing the probe system where the probe device with the sensor is set up. To monitor other traffic in your network, you can configure a monitoring port (if available) that the switch sends a copy of all traffic to. You can then physically connect this port to a network card of the probe system (either local probe or remote probe system). This way, PRTG can analyze the complete traffic that passes through the switch. This feature of your hardware might be called Switched Port Analyzer (SPAN), port mirroring, or port monitoring.

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.

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 do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

icon-i-round-blueUsually, 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.

Setting

Description

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. 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. You can add additional tags to the sensor.

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

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

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, sniffersensor

Sniffer Specific

Setting

Description

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.

icon-square-cyanFor 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.

icon-square-cyanFor detailed information, see section Filter Rules.

Network Adapters

Define the network adapters that this sensor monitors. You see a list of names with all adapters available on the probe system. To select an adapter, set a check mark symbol in front of the respective name. You can also select all items or cancel the selection by using the check box in the table header.

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.

icon-i-round-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

Setting

Description

Channel Selection

Define the categories the sensor accounts the traffic to:

  • 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 are 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-round-redExtensive use of this option can cause load problems on the probe system. We recommend that you set specific, well-chosen filters for the data you really want to analyze.

icon-square-cyanYou 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?

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.

icon-i-round-blueYou 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.
    icon-i-round-blueThis 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

Setting

Description

Primary Toplist

Define which Toplist is your primary Toplist:

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

icon-i-round-blueThe primary Toplist is shown in maps when adding a Toplist object.

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 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 then see the options described below.

Scanning Interval

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

Setting

Description

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.

icon-i-round-blueSensors 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.

icon-i-round-blueIf you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

icon-i-round-blueIf a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

Schedules, Dependencies, and Maintenance Window

icon-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 settings here. They are active at the same time as the parent objects' settings.

Setting

Description

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days or hours) every week.

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

icon-i-round-blueSchedules 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.

icon-i-round-blueTo 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.

icon-i-round-blueTo 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.

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.

Setting

Description

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.

icon-square-cyanFor more details on access rights, see section Access Rights Management.

Channel Unit Configuration

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

Setting

Description

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

icon-i-round-blueCustom channel types can be set on sensor level only.

Toplists

For all xFlow (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.

icon-square-cyanFor more information, see section Toplists.

Filter Rules

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

Field

Possible Filter Values

MAC

Physical address (see Examples)

SourceMAC

Physical address

DestinationMAC

Physical address

EtherType

IPV4, ARP, RARP, APPLE, AARP, IPV6, IPXold, IPX, any number

VlanPCP

IEEE 802.1Q VLAN Priority Code Point

VlanID

IEEE 802.1Q VLAN Identifier

TrafficClass

IPv6 Traffic Class: corresponds to TOS used with IPv4

FlowLabel

IPv6 Flow Label

More

icon-square-bluePRTG MANUAL

 

icon-square-blueKNOWLEDGE BASE

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

Where is the volume line in graphs?

Edit 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: