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. This option is provided as part of the PRTG API.
For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.
- Dutch: SSH Script
- French: Script SSH
- German: SSH-Skript
- Japanese: SSH スクリプト
- Portuguese: SSH Script
- Russian: Скрипт SSH
- Simplified Chinese: SSH 脚本
- Spanish: Secuencia de comandos de SSH
- This sensor can have a high impact on the performance of your monitoring system. 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 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).
- 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.
- For details about the return value format, see section Custom Sensors.
- This sensor has a very high performance impact.
- See the Knowledge Base: SSH and SFTP sensors in Unknown status
The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the setting fields that are required for creating the sensor. Therefore, you do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.
The following settings in the Add Sensor dialog differ in comparison to the sensor's Settings tab.
Setting |
Description |
---|---|
Script |
Select a script file from the dropdown list. It shows all script files 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.
|
Value Type |
Define the type of the values that your script returns:
|
Channel Name |
Enter a name for the channel in which the sensor shows returned values. Enter a string. This is for display purposes only. You can change the name later in the sensor's channel settings. |
Click the Settings tab of a sensor to change its settings.
Usually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.
Setting |
Description |
---|---|
Sensor Name |
Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.
|
Parent Tags |
Shows tags that the sensor inherits from its parent device, parent group, and parent probe. This setting is shown for your information only and cannot be changed here. |
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.
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
|
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 ( |
Sensor Settings
Setting |
Description |
---|---|
Script |
Shows the name of the script that the sensor executes with each scan. Once you have created the sensor, you cannot change this value. It is shown for reference purposes only. If you need to change this value, add the sensor anew. |
Character Encoding |
Define the character encoding you use in your script to correctly display the sensor message:
|
Parameters |
If your script file catches command-line parameters, you can define them here. You can use placeholders as well. Enter a string or leave the field empty.
In SSH scripts, you can use alphanumeric characters and the special characters ".", "_", "-", "=", and "/" outside of quoted strings. |
Mutex Name |
Define any desired mutual exclusion (mutex) name for the process. 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 running at the same time. Enter a string or leave the field empty.
|
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 |
Shows the expected type of the returned value. Once you have created the sensor, you cannot change this value. It is shown for reference purposes only. If you need to change this value, add the sensor anew. |
If Value Changes |
Define what the sensor does when the sensor value changes:
|
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. The maximum value is 900 seconds (15 minutes). Enter an integer value.
|
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 k has sent its specific command (for example, cat /proc/loadavg). The maximum value is 300 seconds (5 minutes). Enter an integer value.
|
SSH Port |
Define which port this sensor uses for the SSH connection:
|
Use Port Number |
This setting is only visible if you enable 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. |
SSH Engine |
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:
|
Result Handling |
Define what PRTG does with the sensor result:
|
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.
|
Graph Type |
Define how different channels are shown for this sensor:
|
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. |
By default, all of the following settings are inherited from objects that are higher in the hierarchy. You should 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. You then see the options described below.
For more information, see section Inheritance of Settings.
Click to interrupt the inheritance.
Setting |
Description |
---|---|
Scanning Interval |
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:
|
If a Sensor Query Fails |
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:
|
Schedules, Dependencies, and Maintenance Windows
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.
Setting |
Description |
---|---|
Schedule |
Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:
|
Maintenance Window |
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:
|
Maintenance Begins |
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. |
Maintenance Ends |
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. |
Dependency Type |
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:
|
Dependency |
This setting is only visible if you enable Select a sensor above. Click |
Dependency Delay (Sec.) |
This setting is only visible if you enable 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.
|
Click to interrupt the inheritance.
Setting |
Description |
---|---|
User Group Access |
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:
|
Click to interrupt the inheritance.
Setting |
Description |
---|---|
Channel Unit Types |
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, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):
|
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 PRTG placeholders instead. See section Custom Sensors for details.
Which channels the sensor actually shows might depend on the monitored 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 value that the script file returns in one channel
|
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?
How and where does PRTG store its data?
For which sensor types do you recommend Windows Server 2012 R2 or later and why?
For more information about sensor settings, see the following sections: