PRTG Manual: SSH Script Sensor
The SSH Script sensor connects to a Linux/Unix system via Secure Shell (SSH) and executes a script file located on the target system. The sensor shows the execution time, and can show one value returned by the executable file or script (in one channel only). For details about the return value format please see the Application Programming Interface (API) Definition.
Note: For security reasons, the script file must be stored on the target system. Please make sure the script has executable rights.
Note: This sensor type can have a high impact on the performance of your monitoring system. Please use it with care! We recommend using not more than 50 sensors, on each probe, of this type of sensor.
For this sensor type credentials for Linux/Solaris/Mac OS (SSH/WBEM) systems must be defined for the device you want to use the sensor on.
Note: Not all Linux/Unix and Mac OS distributions can be supported by this sensor type.
For a general introduction to SSH monitoring, please see Monitoring via SSH section.
The Add Sensor dialog appears when adding a new sensor on a device manually. It only shows the setting fields that are imperative for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change all settings in the sensor's Settings tab later.
The following settings for this sensor differ in the 'Add Sensor' dialog in comparison to the sensor's settings page:
Sensor Settings |
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Script |
Select a script file from the list. The drop down menu will list all script files available in the /var/prtg/scripts directory on the target Linux/Unix system. In order for the files to appear in this list, please store them into this directory. Please make sure the script has executable rights. In order for the sensor to show the expected values and sensor status, your files must use the right format for the returned values (in this case, exitcode:value:message to stdout). The exitcode will determine the sensor status. For detailed information on the expected return format and on how to build custom sensors, please see the API documentation (Application Programming Interface (API) Definition). There, find detailed information the the "Custom Sensors" tab. For an example script, please see More section below. |
Value Type |
Define what kind of values your script file gives back. Choose between:
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On the sensor's details page, click on the Settings tab to change settings.
Note: If not set explicitly in a sensor's settings, it will connect to the IP Address or DNS Name defined in the settings of the parent device the sensor is created on.
Basic Sensor Settings |
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Sensor Name |
Enter a meaningful name to identify the sensor. The name will be shown by default in the device tree and in all alarms. |
Tags |
Enter one or more tags, separated by space or comma. You can use tags to group sensors and use tag-filtered views later on. Tags are not case sensitive. We recommend using the default value. You can add additional tags to it, if you like. Other tags are automatically inherited from objects further up in the device tree. Those are not visible here. |
Priority |
Select a priority for the sensor. This setting determines where the sensor will be placed in sensor lists. Top priority will be at the top of a list. You can choose from one star (low priority) to five stars (top priority). |
Sensor Settings |
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Script |
Shows the script that is executed with each sensor scan, as defined on sensor creation. Once a sensor is created this value cannot be changed. It is shown for reference purposes only. If you need to change this, please add the sensor anew. |
Parameters |
If your script file catches command line parameters, you can define them here. Placeholders can be used as well. For a full list of all placeholders please see the API documentation (Application Programming Interface (API) Definition). Note: Please make sure you write the placeholders in quotes to ensure that they are working properly if their values contain blanks. Use single quotation marks ' ' with PowerShell scripts, and double quotes " " with all others. Please enter a string or leave the field empty. |
Mutex Name |
Define any desired mutex name for the process. All EXE/Script sensors having the same mutex name will be executed serially (not simultaneously). This is useful if you use a lot of sensors and want to avoid high resource usage caused by processes running simultaneously. For links to more information, please see the More section below. Please enter a string or leave the field empty. |
Value Type |
Shows the expected value type, chosen on sensor creation. Once a sensor is created this value cannot be changed. It is shown for reference purposes only. If you need to change this, please add the sensor anew. Note: The sensor cannot handle string values. |
If Value Changes |
Define what shall be done in case the value of this sensor changes. You can choose between:
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SSH Specific |
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Connection Timeout (Sec.) |
Define a timeout for the connection. This is the the time the sensor waits to establish a connection to the host. You should keep this value as low as possible. |
Shell Timeout (Sec.) |
Define a timeout 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 (e.g. cat /proc/loadavg). |
SSH Port |
Define which port this sensor will use for the SSH connection. Choose between:
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Use Port Number |
This field is only visible if the custom port number setting is enabled above. Enter the port number this sensor will use for the SSH connection. Please enter an integer value. |
Result Handling |
Define what will be done with the result of the sensor. Choose between:
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Sensor Display |
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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 will always be displayed underneath the sensor's name. The available options depend on what channels are available for this sensor. Note: You can set another primary channel later by clicking on the pin symbol of a channel in the sensor's overview tab. |
Chart Type |
Define how different channels will be shown for this sensor.
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Stack Unit |
This setting is only available if stacked graphs are selected above. Choose a unit from the list. All channels with this unit will be 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. |
By default, all following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings. To change a setting for this object, disable inheritance by clicking on the check mark symbol in front of the respective setting name. You will then see the options described below.
Scanning Interval |
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Scanning Interval |
The scanning interval determines the time the sensor waits between two scans. Select a scanning interval (seconds, minutes, or hours) from the list. You can change the available intervals in the system administration. |
Schedules, Dependencies, and Maintenance Window |
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Note: Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted; the according settings from the parent objects will always be active. However, you can define additional settings here. They will be active in parallel to the parent objects' settings. |
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Schedule |
Select a schedule from the list. Schedules can be used to monitor for a certain time span (days, hours) throughout the week. With the period list option it is also possible to pause monitoring for a specific time span. You can create new schedules and edit existing ones in the account settings. Note: Schedules are generally inherited. New schedules will be added to existing ones, so all schedules are active. |
Maintenance Window |
Specify if you want to set-up a one-time maintenance window. During a maintenance window this object and all child objects will not be monitored. They will enter a paused state then. Choose between:
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Maintenance Begins At |
This field is only visible if maintenance window is enabled above. Use the date time picker to enter the start date and time of the maintenance window. |
Maintenance End At |
This field is only visible if maintenance window is enabled above. Use the date time picker to enter the end date and time of the maintenance window. |
Dependency Type |
Define a dependency type. Dependencies can be used to pause monitoring for an object depending on the status of another. You can choose between:
Note: Testing your dependencies is easy! Simply choose Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later all dependent objects should be paused. |
Dependency |
This field is only visible if the select object option is enabled above. Click on the reading-glass symbol and use the object selector to choose an object on which the current sensor will be dependent on. |
Delay (Seconds) |
Define a time span. After the master object for this dependency comes back to an Up status, monitoring of the depending objects will be additionally delayed by the defined time span. This can help avoid false alarms, for example, after a server restart, by giving systems more time for all services to start up. Please enter an integer value in seconds. Note: This setting is not available if you choose this sensor to be the Master object for parent. In this case, please define delays in the parent Device Settings or the superior Group Settings. |
Access Rights |
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User Group Access |
Define which user group(s) will have access to the object you're editing. A table with user groups and right is shown; it contains all user groups from your setup. For each user group you can choose from the following access rights:
You can create new user groups in the System Administration—User Groups settings. To automatically set all objects further down in the hierarchy to inherit this object's access rights, set a check mark for the Revert children's access rights to inherited option. For more details about access rights, please see section User Access Rights. |
Channel Unit Configuration |
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Channel Unit Types |
For each type of sensor 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):
Note: Custom channel types can be set on sensor level only. |
Knowledge Base: Is there a shell script example for PRTG's SSH Script Sensor?
Information about custom scripts and executables
Knowledge Base: What is the Mutex Name in PRTG's EXE/Script Sensor's settings?
Knowledge Base: How and Where Does PRTG Store its Data?
Knowledge Base: How can I test if parameters are correctly transmitted to my script when using an EXE/Script sensor?
In order to change display settings, spike filter, and limits, please switch to the sensor's Overview tab and click on the gear icon of a specific channel. For detailed information, please see Sensor Channels Settings section.
Click on the Notifications tab to change notification triggers. For detailed information, please see Sensor Notifications Settings section.
For more general information about settings, please see Object Settings section.
For information about sensor settings, please see the following sections:
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