PRTG Manual: SNMP Custom String Sensor

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).

OID Values

OID Value

Enter the OID of the SNMP object you want to receive a string from.

If Value Changes

Define what shall be done in case the value of this sensor changes. You can choose between:

• Ignore changes (default): No action will be taken on change.
• Trigger 'On Change' notification: The sensor will send an internal message indicating that its value has changed. In combination with a Change Trigger, you can use this mechanism to trigger a notification whenever the sensor value changes.

Response Must Include

Define which string must be part of the data that is received form the SNMP object at the given OID. You can either enter plain text or a Regular Expression. If the data does not include the search pattern, the sensor will be set to an error state. Please enter a string or leave the field empty.

For Keyword Search Use

Define in which format you have entered the search expression in the field above.

• Plain Text: Search for the string as plain text. The characters * and ? work here as placeholder, whereas * stands for no or any number of characters and ? stands for exactly one character (as known from Windows search). This behavior cannot be disabled, so the literal search for these characters is not possible with plain text search.

• Regular Expression: Treat the search pattern as a Regular Expression.

Response Must Not Include

Define which string must not be part of the data that is received form the SNMP object at the given OID. You can either enter plain text or a Regular Expression. If the data does not include the search pattern, the sensor will be set to an error state. Please enter a string or leave the field empty.

For Keyword Search Use

Define in which format you have entered the search expression in the field above.

• Plain Text: Search for the string as plain text. The characters * and ? work here as placeholder, whereas * stands for no or any number of characters and ? stands for exactly one character (as known from Windows search). This behavior cannot be disabled, so the literal search for these characters is not possible with plain text search.

• Regular Expression: Treat the search pattern as a Regular Expression.

Maximum Length of String

Define the maximum length of the string that will be received from the SNMP object at the given OID. If the length is greater than this value, the sensor will be set to an error state. Please enter an integer value or leave the field empty.

Extract Number using Regular Expression

Define if you want to filter out a numeric value from the string received from the SNMP object at the given OID. You can convert this into a float value, in order to use it with channel limits (see Sensor Channels Settings).

• No extraction: Do not extract a float value. Use the result as a string value.

• Extract a numeric value using a regular expression: Use a regular expression to identify a numeric value in the string and convert it to a float value. Define below.

Regular Expression

This setting is only visible if number extraction is enabled above. Enter a Regular Expression to identify the numeric value you want to extract from the string returned by the SNMP object at the given OID. You can use capturing groups here. Make sure the expression returns numbers only (including decimal and thousands separators). The result will be further refined by the settings below.

Index of Capturing Group

This setting is only visible if number extraction is enabled above. If your regular expression uses capturing groups, please specify which one will be used to capture the number. Please enter an integer value or leave the field empty.

Decimal Separator

This setting is only visible if number extraction is enabled above. Define which character is used as decimal separator for the number extracted above. Please enter a string or leave the field empty.

Thousands Separator

This setting is only visible if number extraction is enabled above. Define which character is used as thousands separator for the number extracted above. Please enter a string or leave the field empty.

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.

Chart Type

Define how different channels will be shown for this sensor.

• Show channels independently (default): Show an own 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 will generate an easy-to-read graph which visualizes the different components of your total traffic. Note: This option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channels Settings settings).

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.

Scanning Interval

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.

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.

Schedule

Select a schedule from the list. Schedules can be used to pause monitoring for a certain time span (days, hours) throughout the week. 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:

• Not set (monitor continuously): No maintenance window will be set.
• Set up a one-time maintenance window: Pause monitoring within a maintenance window.

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:

• Use parent: Pause the current sensor if the device it is created on is in a Down status, or if it is paused by another dependency.
• Select object: Pause the current sensor if the device it is created on is in an Down status, or if it is paused by another dependency. Additionally, pause the current sensor if a specific other object in the device tree is in a Down status, or if it is paused by another dependency. Select below.
• Master object for parent: Make this sensor the master object for its parent device. The sensor will influence the behavior of the device it is created on: If the sensor is in a Down status, the device will be 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 will be paused if the parent group of its parent device is in a Down status, or if it is paused by another dependency.

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

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:

• Inherited: Use the settings of the parent object.
• None: Users in this group cannot see or edit the object. The object does not show up in lists and in the device tree. Exception: If a child object is visible to the user, the object is visible in the device tree, though not accessible.
• Read: Users in this group can see the object and review its monitoring results.
• Write: Users in this group can see the object, review its monitoring results, and edit the object's settings. They cannot edit access rights settings.
• Full: Users in this group can see the object, review its monitoring results, edit the object's settings, and edit access rights settings.

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.