<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> 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
For 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
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
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Script
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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 detailed information on how to create custom sensors and for the return format, see section Custom Sensors.
For an example script, see the Knowledge Base: Is there a shell script example for the SSH Script sensor?
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Value Type
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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 integer values 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.
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Channel Name
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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.
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Basic Sensor Settings
Click the Settings tab of a sensor to change its settings.
Basic Sensor Settings
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Sensor Name
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Enter a name to identify the sensor.
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Parent Tags
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Shows tags that the sensor inherits from its parent device, parent group, and parent probe.
This setting is for your information only. You cannot change it.
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Tags
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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.
It is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).
For 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:
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Priority
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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 () to the highest priority ().
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Sensor Settings
Sensor Settings
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Script
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Shows the name of the script that the sensor executes with each scanning interval.
PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.
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Character Encoding
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Define the character encoding that you use in your script to correctly display the sensor message:
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Parameters
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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 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.
In SSH scripts, you can use alphanumeric characters and the special characters ".", "_", "-", "=", and "/" outside of quoted strings.
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Mutex Name
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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?
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Unit String
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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.
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Value Type
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Shows the expected type of the returned value.
PRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.
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If Value Changes
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Define what the sensor does when the sensor value changes:
- Ignore changes (default): Take no action on change.
- Trigger 'change' notification: Send an internal message indicating that the sensor value has changed. In combination with a change trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.
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SSH Specific
SSH Specific
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Connection Timeout (Sec.)
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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 value.
Ensure that the connection timeout is a value that is higher than the shell timeout to avoid potential errors.
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Shell Timeout (Sec.)
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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 value.
Ensure that the shell timeout is a value that is lower than the connection timeout to avoid potential errors.
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SSH Port
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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.
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Use Port Number
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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 value.
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SSH Engine
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Select the method that you want to use to access data with this SSH sensor. We strongly recommend that you use the default engine. You can still use the legacy mode for some time to ensure compatibility with your target systems. 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 default engine.
- Default: This is the default monitoring method for SSH sensors. 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): Try this legacy method only if the default mode 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 running with 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.
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Result Handling
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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.
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.
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Sensor Display
Sensor Display
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Primary Channel
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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 below a channel gauge on the sensor's Overview tab.
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Graph Type
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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.
You cannot use this option in combination with manual Vertical Axis Scaling (available in the channel settings).
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Stack Unit
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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.
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Inherited Settings
By default, all of the following 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 under the corresponding setting name to disable the inheritance and to display its options.
For more information, see section Inheritance of Settings.
Scanning Interval
Click to interrupt the inheritance.
Scanning Interval
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Scanning Interval
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Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:
- 30 seconds
- 60 seconds
- 5 minutes
- 10 minutes
- 15 minutes
- 30 minutes
- 1 hour
- 4 hours
- 6 hours
- 12 hours
- 24 hours
You can change the available intervals in the system administration of PRTG Network Monitor.
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If a Sensor Query Fails
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Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the 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 the Warning status. Choose from:
- Set sensor to down immediately: Set the sensor to the Down status immediately after the first request fails.
- Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to the Warning status after the first request fails. If the second request also fails, the sensor shows the Down status.
- Set sensor to warning for 2 intervals, then set to down: Set the sensor to the Down status only after the third request fails.
- Set sensor to warning for 3 intervals, then set to down: Set the sensor to the Down status only after the fourth request fails.
- Set sensor to warning for 4 intervals, then set to down: Set the sensor to the Down status only after the fifth request fails.
- Set sensor to warning for 5 intervals, then set to down: Set the sensor to the Down status only after the sixth request fails.
Sensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show the Down status. It is not possible to immediately set a WMI sensor to the 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 the Down status. None of the interval options apply.
If a channel uses lookup values, the sensor immediately shows the Down status. None of the interval options apply.
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Schedules, Dependencies, and Maintenance Window
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 schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.
Schedules, Dependencies, and Maintenance Window
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Schedule
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Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:
- None
- Saturdays
- Sundays
- Weekdays
- Weekdays Eight-To-Eight (08:00 - 20:00)
- Weekdays Nights (17:00 - 09:00)
- Weekdays Nights (20:00 - 08:00)
- Weekdays Nine-To-Five (09:00 - 17:00)
- Weekends
You can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Schedules.
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Maintenance Window
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Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:
- Do not set up a one-time maintenance window: Do not set up a one-time maintenance window. Monitoring is always active.
- Set up a one-time maintenance window: Set up a one-time maintenance window and pause monitoring. You can define a time span for the pause below.
To terminate an active maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.
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Maintenance Begins
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This setting 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 one-time maintenance window.
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Maintenance Ends
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This setting 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 one-time maintenance window.
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Dependency Type
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Select 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 the Down status or in the Paused status because of 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 the 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.
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Dependency
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This setting is only visible if you enable Select a sensor above. Click and use the object selector to select a sensor on which the current object will depend.
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Dependency Delay (Sec.)
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This setting is only visible if you select Select a sensor above. Define a time span in seconds for the dependency delay.
After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. 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.
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Access Rights
Click to interrupt the inheritance.
Access Rights
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User Group Access
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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.
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Channel Unit Configuration
Click to interrupt the inheritance.
Which 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
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Channel Unit Types
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For each type of channel, select the unit in which PRTG displays the data. If you define this setting on probe, group, or device level, you can inherit these settings to all sensors underneath. You can set units for the following channel types (if available):
- Bandwidth
- Memory
- Disk
- File
- Custom
Custom channel types are only available on sensor level.
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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"
In SSH scripts, you can use alphanumeric characters and the special characters ".", "_", "-", "=", and "/" outside of quoted strings.
We recommend that you do not pass passwords in parameters. Use placeholders instead. See section Custom Sensors for details.
Channel List
Which channels the sensor actually shows might depend on the monitored device, the available components, and the sensor setup.
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Downtime
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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.
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Execution Time
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The execution time in milliseconds (msec)
This channel is the primary channel by default.
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[Value]
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The value that the script file returns in one channel
For details about the return value format, see section Custom Sensors.
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More
Knowledge Base
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 Windows Server 2012 R2 or later and why?
Sensor Settings Overview
For more information about sensor settings, see the following sections: