PRTG Manual: SSH Script Sensor

The SSH Script 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 Sensor

SSH Script 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
  • French: Script (SSH)
  • German: SSH-Skript
  • Japanese: SSH スクリプト
  • Portuguese: Script (SSH)
  • Russian: Скрипт SSH
  • Simplified Chinese: SSH 脚本
  • Spanish: Script (SSH)

Remarks

Consider the following remarks and requirements for this sensor:

Remark

Description

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.

File storage

For security reasons, this sensor requires that you store your script file in the /var/prtg/scripts directory on the target system. Make sure that the script has executable rights. If the script is not available or was deleted from the directory, you get the error message Script not found (237).

Credentials

This sensor requires credentials for Linux/Solaris/macOS (SSH/WBEM) systems in the settings of the parent device.

Distributions

This sensor does not support all Linux/Unix and macOS distributions.

IPv4

This sensor only supports IPv4.

Return format

For more information about the return value format, see the PRTG Manual: Custom Sensors.

Knowledge Base

Add Sensor

Setting

Description

Channel Name

Enter a name for the channel. Enter a string. This is for display purposes only.

i_round_blueYou can change this value later in the channel settings of this sensor.

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:

  • sshscript

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

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

Select a script file from the dropdown list. It shows all script files that are available in the /var/prtg/scripts 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 file must use the correct format for the returned values. In this case, it is exitcode:value:message to standard output stdout. The exit code determines the sensor status.

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

i_square_cyanFor more information and an example script, see the Knowledge Base: Is there a shell script example for the SSH Script sensor?

i_round_blueYou cannot change this value after sensor creation.

Character Encoding

Define the character encoding that you use in your script to correctly display the sensor message:

  • UTF-8 (default)
  • ASCII

Parameters

If your script file catches command-line parameters, define them here. You can also use 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 need to escape special characters and whitespaces in your parameters and surround them with double quotation marks ("). 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?

Unit String

Define a unit for the channel value. Enter a string. This is for display purposes only and is the default unit for a new channel. You can change the unit after sensor creation in the sensor's channel settings.

Value Type

Define the type of the values that your executable or script file returns:

  • Integer: An integer is expected as return value. If the script returns a float, PRTG displays the value 0.
  • Float: A float is expected as return value, with a dot (.) between the predecimal position and the decimal places.
    i_round_blueThe sensor also displays integers unless they produce a buffer overflow.
  • Counter: Your script returns an integer that increases. PRTG shows the difference between the values of two sensor scans.
    i_round_redA counter must return an integer. It does not support float values.

i_round_redThe sensor does not support string values.

i_round_blueYou cannot change this value after sensor creation.

If Value Changes

Define what the sensor does when its value changes:

  • Ignore (default): Do nothing.
  • Trigger 'change' notification: Send an internal message that indicates a change.
    i_round_blueIn combination with a change trigger, you can use this to trigger a notification if a change occurs.

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

SSH Port Inheritance

Define which port this sensor uses for the SSH connection:

  • Inherit port 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.
  • Do not inherit port (enter a custom SSH port): Define a custom port number below and do not use the port number from the parent device settings.

Custom SSH Port

This setting is only visible if you select Do not inherit port (enter a custom SSH port) 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:

  • 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 (default): 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, 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.

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.

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

Execution Time

The execution time

i_round_blueThis channel is the primary channel by default.

[Value]

The value that the script file returns in one channel

i_square_cyanFor more information 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

Is there a shell script example for the SSH Script sensor?

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 2016 and why?