PRTG Manual: SSH Script Sensor

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

• Knowledge Base: Which encryption algorithms do PRTG SSH sensors support?
• Knowledge Base: SSH and SFTP sensors in Unknown status

Channel Name

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

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

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.

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.

Make sure that the script has executable rights.

To 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.

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

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

You 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.

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

You 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.

In 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.

PRTG 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.

See 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.
  The 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.
  A counter must return an integer. It does not support float values.

The sensor does not support string values.

You 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.
  In combination with a change trigger, you can use this to trigger a notification if a change occurs.

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.

Make 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.

Make 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.

We strongly recommend that you use the default SSH engine.

The 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.

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

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

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.

You can set a different primary channel later by clicking 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.
  You 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.

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

This channel is the primary channel by default.

[Value]

The value that the script file returns in one channel

For more information about the return value format, see section Custom Sensors.