PRTG Manual: SNMP Custom String Sensor

Sensor Name

Enter a 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.

If the name contains angle brackets (<>), PRTG replaces them with braces ({}) for security reasons. For more information, see the Knowledge Base: What security features does PRTG include?

Parent Tags

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.

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.

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:

• snmpcustomstringsensor

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 () to the highest priority ().

OID

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

Most OIDs begin with 1.3.6.1. However, OIDs that start with 1.0, or 1.1, or 1.2 are also allowed. If you want to entirely disable the validation of your entry, add the string norfccheck: to the beginning of the OID, for example, norfccheck:2.0.0.0.1.

Maximum String Length

Define the maximum length of the string that PRTG receives from the SNMP object at the OID. If the string is longer than this value, the sensor shows the Down status. Enter an integer or leave the field empty.

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.

Response Must Include (Down Status if Not Included)

Define the search string that must be part of the data that PRTG receives from the SNMP object at the OID. You can enter a simple string in plain text or a regular expression (regex).

The search string must be case sensitive.

If the data does not include the search pattern, the sensor shows the Down status.

Search Method

Define the method with which you want to provide the search string.

• Simple string search: Search for a simple string in plain text.
  The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.
• Regular expression: Search with a regex.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

Response Must Not Include (Down Status if Included)

Define the search string that must not be part of the data that PRTG receives form the SNMP object at the OID. You can enter a simple string in plain text or a regex.

The search string must be case sensitive.

If the data does include the search pattern, the sensor shows the Down status.

Search Method

Define the method with which you want to provide the search string.

• Simple string search: Search for a simple string in plain text.
  The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.
• Regular expression: Search with a regex.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

Response Must Include (Warning Status If Not Included)

Define the search string that must be part of the data that PRTG receives from the SNMP object at the OID. You can enter a simple string in plain text or a regex.

The search string must be case sensitive.

If the data does not include the search pattern, the sensor shows the Warning status.

Search Method

Define the method with which you want to provide the search string.

• Simple string search: Search for a simple string in plain text.
  The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.
• Regular expression: Search with a regex.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

Response Must Not Include (Warning Status If Included)

Define the search string that must not be part of the data that PRTG receives form the SNMP object at the OID. You can enter a simple string in plain text or a regex.

The search string must be case sensitive.

If the data does include the search pattern, the sensor shows the Warning status.

Search Method

Define the method with which you want to provide the search string.

• Simple string search: Search for a simple string in plain text.
  The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character. You cannot change this behavior. The literal search for these characters is only possible with a regex.
• Regular expression: Search with a regex.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

Interpret Result As

Define the type of the received string:

• String (default): Handle the result as a common string.
• Bytes in hexadecimal notation: Handle the result as bytes in hexadecimal notation. For example, select this option if you monitor MAC addresses.
• Bytes in decimal notation: Handle the result as bytes in decimal notation. For example, select this option if you monitor IP addresses.

Numeric Value Extraction

Define if you want to filter out a numeric value from the received string:

• Do not use extraction: Do not extract a float value. Use the result as a string value.
• Use a regular expression for extraction: Use a regular expression (regex) to identify a numeric value in the string and to convert it to a float value to use it, for example, with channel limits. Define below. See also the example.
  For more information, see section Channel Settings.

Regular Expression

This setting is only visible if you select Use a regular expression for extraction above. Enter a regular expression to identify the numeric value that you want to extract from the string returned by the SNMP object at the specified OID. You can use capturing groups.

Make sure that the expression only returns numbers, including the decimal and thousands separators.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

Index of Capturing Group

This setting is only visible if you select Use a regular expression for extraction above. If your regex uses capturing groups, specify which one captures the number. Enter an integer or leave the field empty.

Decimal Separator

This setting is only visible if you select Use a regular expression for extraction above. Define the character for the decimal separator of the number. Enter a string or leave the field empty.

Thousands Separator

This setting is only visible if you select Use a regular expression for extraction above. Define the character for the thousands separator of the number. 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 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.

Graph Type

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).

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.

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

Extracted Value

The value extracted from the string (optional)

Response Time

The response time

This channel is the primary channel by default.