PRTG Manual: SSH Script Advanced Sensor

The SSH Script Advanced sensor connects to a Linux/Unix system via Secure Shell (SSH) and executes a script file that is located on the target system. This option is available as part of the PRTG API.

SSH Script Advanced Sensor

SSH Script Advanced 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: SSH Script Geavanceerd
  • French: Script (SSH) avancé
  • German: SSH-Skript (Erweitert)
  • Japanese: SSH スクリプト(詳細)
  • Portuguese: Script (avançado) (SSH)
  • Russian: Расширенный скрипт SSH
  • Simplified Chinese: 高级 SSH 脚本
  • Spanish: Script (avanzado) (SSH)

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.
  • For security reasons, you must store the script file in the /var/prtg/scriptsxml directory on the target system. Make sure that the script has executable rights.
  • This sensor requires credentials for Linux/Solaris/macOS (SSH/WBEM) systems in the settings of the parent device.
  • This sensor cannot support all Linux/Unix and macOS distributions.
  • 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.
  • This sensor only supports the IPv4 protocol.
  • For details about the return value format, see section Custom Sensors.

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.

Sensor Settings

Setting

Description

Script

Select a script file from the dropdown list. It shows all script files that are available in the /var/prtg/scriptsxml directory on the target Linux/Unix system. For a script file to appear in this list, store the target file in this directory.

i_round_redMake sure that the script has executable rights.

i_round_redTo show the expected sensor value and status, your files must return the expected XML or JSON format to standard output stdout. The values and message must be embedded in the XML or JSON.

i_square_cyanFor detailed information on how to create custom sensors and for the return format, see section Custom Sensors.

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:

  • sshscript

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).

Credentials for Script Sensors

Click b_inherited_enabled to interrupt the inheritance.

Credentials for Script Sensors

Credentials for Script Sensors

Setting

Description

Placeholder 1 Description

Enter a description for Placeholder 1, for example information about the purpose or content of the placeholder.

Placeholder 1

Enter a value for the placeholder. PRTG inserts the value for the script execution if you add %scriptplaceholder1 in the argument list. PRTG does not display the value in the sensor log or the sensor's settings.

Placeholder 2 Description

Enter a description for Placeholder 2, for example information about the purpose or content of the placeholder.

Placeholder 2

Enter a value for the placeholder. PRTG inserts the value for the script execution if you add %scriptplaceholder2 in the argument list. PRTG does not display the value in the sensor log or the sensor's settings.

Placeholder 3 Description

Enter a description for Placeholder 3, for example information about the purpose or content of the placeholder.

Placeholder 3

Enter a value for the placeholder. PRTG inserts the value for the script execution if you add %scriptplaceholder3 in the argument list. PRTG does not display the value in the sensor log or the sensor's settings.

Placeholder 4 Description

Enter a description for Placeholder 4, for example information about the purpose or content of the placeholder.

Placeholder 4

Enter a value for the placeholder. PRTG inserts the value for the script execution if you add %scriptplaceholder4 in the argument list. PRTG does not display the value in the sensor log or the sensor's settings.

Placeholder 5 Description

Enter a description for Placeholder 5, for example information about the purpose or content of the placeholder.

Placeholder 5

Enter a value for the placeholder. PRTG inserts the value for the script execution if you add %scriptplaceholder5 in the argument list. PRTG does not display the value in the sensor log or the sensor's settings.

Sensor Settings

Sensor Settings

Sensor Settings

Setting

Description

Script

Shows the script that the sensor executes with each scanning interval.

i_round_bluePRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

Parameters

If your script file catches command-line parameters, you can define them here. You can use also placeholders. Enter a string or leave the field empty.

i_square_cyanFor a full list of all placeholders, see section Custom Sensors.

i_round_redYou must escape special characters and whitespaces in your parameters and surround them with double quotes. See section Escape Special Characters and Whitespaces in Parameters for details.

i_round_blueIn SSH scripts, you can use alphanumeric characters and the special characters ".", "_", "-", "=", and "/" outside of quoted strings.

Mutex Name

Define a mutual exclusion (mutex) name for the process. Enter a string or leave the field empty.

i_round_bluePRTG runs all custom script sensors that have the same mutex name serially (not simultaneously). This is useful if you use a lot of sensors and want to avoid high resource usage caused by processes that run running at the same time.

i_square_cyanSee the Knowledge Base: What is the Mutex Name in the EXE/Script sensor settings?

SSH Specific

SSH Specific

SSH Specific

Setting

Description

Connection Timeout (Sec.)

Define a timeout in seconds for the connection. This is the time that the sensor waits to establish a connection to the host. Keep this value as low as possible. Enter an integer.

i_round_blueEnsure that the connection timeout is a value that is higher than the shell timeout to avoid potential errors.

Shell Timeout (Sec.)

Define a timeout in seconds for the shell response. This is the time in seconds the sensor waits for the shell to return a response after it has sent its specific command (for example, cat /proc/loadavg). The maximum value is 300 seconds (5 minutes). Enter an integer.

i_round_blueEnsure that the shell timeout is a value that is lower than the connection timeout to avoid potential errors.

SSH Port

Define which port this sensor uses for the SSH connection:

  • Inherit port number from parent device (default): Use the port number as defined in the Credentials for Linux/Solaris/macOS (SSH/WBEM) Systems section of the parent device settings.
  • Enter custom port number: Define a custom port number below and do not use the port number from the parent device settings.

Use Port Number

This setting is only visible if you select Enter custom port number above. Enter the port number (between 1 and 65535) that this sensor uses for the SSH connection. Enter an integer.

SSH Engine

Select the SSH engine that you want to use to access data with this SSH sensor. Choose between:

  • Inherit from parent device (default): Use the SSH engine that you defined in the parent device settings or higher up in the object hierarchy. If you have not changed the SSH engine, this is the recommended option.
  • Default: This is the default SSH engine. It provides the best performance and security. It is set by default in objects that are higher up in the hierarchy, so usually you can keep the Inherit from parent device (default) option.
  • Compatibility mode (deprecated): Use this only if the default SSH engine does not work on a target device. The compatibility mode is the SSH engine that PRTG used in previous versions. It is deprecated. We will remove this legacy mode soon, so try to get your SSH sensors to run with the default SSH engine.

i_round_redWe strongly recommend that you use the default SSH engine.

i_round_redThe option you select here overrides the selection of the SSH engine in a higher object: a parent device, group, probe, or root.

Result Handling

Define what PRTG does with the sensor result:

  • Discard result: Do not store the sensor result.
  • Store result: Store the last sensor result in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID].txt, Result of Sensor [ID].Data.txt, and Result of Sensor [ID] (SSHv2).txt. This setting is for debugging purposes. PRTG overwrites these files with each scanning interval.
  • Store result in case of error: Store the last sensor result only if the sensor shows the Down status.

i_podThis option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance.

i_round_blueIn a cluster, PRTG stores the result in the PRTG data directory of the master node.

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.

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

i_round_blueWhich channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.

Channel Unit Configuration

Channel Unit Configuration

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

Escape Special Characters and Whitespaces in Parameters

You need to escape special characters in parameters that you pass to an executable or script and surround them with quotation marks to make sure that the characters are correctly interpreted. PowerShell scripts in particular require adequate escaping so that the parameters are passed in a valid PowerShell syntax. PRTG automatically does most of the escaping for you.

Follow these rules to escape special characters and whitespaces in the parameters fields:

  • Use quotes for parameters that contain whitespaces.

-name "Mr John Q Public"
-name 'Mr John Q Public'

  • Use double quotes for parameters that contain single quotes.

-name "Mr 'John Q' Public"

  • Use single quotes for parameters that contain double quotes.

-name 'Mr "John Q" Public'

  • Use a backslash (\) to escape and pass a literal double quote.

-name pub\"lic

  • Use double quotes for parameters that contain double and single quotes and escape double quotes.

-name "pu'b\"lic"

i_round_blueIn SSH scripts, you can use alphanumeric characters and the special characters ".", "_", "-", "=", and "/" outside of quoted strings.

i_round_blueWe recommend that you do not pass passwords in parameters. Use placeholders instead. See section Custom Sensors for details.

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

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.

Execution Time

The execution time in milliseconds (msec)

[Value]

The values that the script file returns in several channels

i_square_cyanFor details about the return value format, see section Custom Sensors.

More

i_square_blueKnowledge Base

Which encryption algorithms do PRTG SSH sensors support?

SSH and SFTP sensors in Unknown status

What security features does PRTG include?

What is the Mutex Name in the EXE/Script sensor settings?

How can I test if parameters are correctly transmitted to my script when using an EXE/Script sensor?

How can I show special characters with EXE/Script sensors?

Why do I have to store SQL sensor queries and custom scripts in files on the probe computer?

For which sensor types do you recommend at least Windows Server 2012 R2 and why?