PRTG Manual: HTTP Content Sensor

The HTTP Content sensor monitors numeric values returned by an HTTP request.

i_round_redIn the returned HTML page, each value must be placed between brackets [ ]. See section Example.

HTTP Content Sensor

HTTP Content Sensor

i_square_cyanFor a detailed list and descriptions of the channels that this sensor can show, see section Channel List.

Sensor in Other Languages

  • Dutch: HTTP (Inhoud)
  • French: Contenu (HTTP)
  • German: HTTP (Inhalt)
  • Japanese: HTTP コンテンツ
  • Portuguese: Conteúdo HTTP
  • Russian: HTTP: Содержимое
  • Simplified Chinese: HTTP 内容
  • Spanish: Contenido HTTP

Remarks

  • This sensor does not officially support more than 50 channels. Depending on the data used with this sensor, you might exceed the maximum number of supported channels. In this case, PRTG tries to display all channels. Be aware, however, that you experience limited usability and performance.
  • This sensor does not support Secure Remote Password (SRP) ciphers.
  • This sensor supports smart URL replacement.
  • This sensor supports the IPv6 protocol.
  • This sensor has a medium performance impact.
  • For an example configuration, see section Example.
  • See the Knowledge Base: How can I monitor internal values of a web application with PRTG?
  • See the Knowledge Base: Which HTTP status code leads to which HTTP sensor status?

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.

HTTP Specific

Setting

Description

Value Type

Define what kind of values the .html file returns:

  • Integer: Returns integers.
  • Float: Returns floats with a dot . between the predecimal position and the decimal places. The sensor also displays integers unless they do not produce a buffer overflow.

i_round_blueThe sensor cannot handle string values.

Number of Channels

Define how many values the .html file returns. The sensor handles each value in its own channel. Each value must be placed between brackets [ ]. Enter the number of bracket-value pairs that the URL returns. Enter an integer.

i_round_redDo not enter a number that is smaller than the number of values that the HTTP request returns. Otherwise, you get an error message.

Basic Sensor Settings

Click the Settings tab of a sensor to change its settings.

Basic Sensor Settings

Basic Sensor Settings

Setting

Description

Sensor Name

Enter a name to identify the sensor.

Parent Tags

Shows tags that the sensor inherits from its parent device, parent group, and parent probe.

i_round_blueThis 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.

i_round_blueIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

i_round_blueFor 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:

  • httpsensor

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 (i_priority_1) to the highest priority (i_priority_5).

i_round_blueUsually, a sensor connects to the IP Address/DNS Name of the parent device. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings.

HTTP Specific

HTTP Specific

HTTP Specific

Setting

Description

Timeout (Sec.)

Enter a timeout in seconds for the request. Enter an integer. The maximum timeout value is 900 seconds (15 minutes).

i_round_blueIf the reply takes longer than this value, the sensor cancels the request and shows a corresponding error message.

Script URL

Enter the URL that the sensor connects to. If you enter an absolute URL, the sensor uses this address independently of the IP Address/DNS Name setting of the parent device.

i_round_redThe URL must be URL encoded.

i_square_cyanPRTG uses a smart URL replacement with which you can use the parent device's IP address or Domain Name System (DNS) name setting as part of the URL. For more information, see section Smart URL Replacement.

Value Type

Shows the kind of values that the .html file returns.

i_round_bluePRTG shows this value for reference purposes only. If you need to change this value, add the sensor anew.

i_round_blueThis sensor implicitly supports SNI, an extension to the Transport Layer Security (TLS) protocol.

Advanced Sensor Data

Advanced Sensor Data

Advanced Sensor Data

Setting

Description

If Content Changes

Define what the sensor does if the content of the web page changes:

  • Ignore changes: Take no action on change.
  • Trigger 'change' notification: Send an internal message that indicates changes to the web page content. In combination with a change trigger, you can use this mechanism to trigger a notification when the web page content changes.

Result Handling

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 and Result of Sensor [ID].Data.txt. This setting is for debugging purposes. PRTG overwrites these files with each scanning interval.

i_podThis option is not available when the sensor runs on the hosted probe of a PRTG Hosted Monitor instance.

i_round_blueIn a cluster, PRTG stores the result in the PRTG data directory of the master node.

Authentication

Authentication

Authentication

Setting

Description

Authentication

Define if authentication is necessary on the web page:

  • Web page does not need authentication
  • Web page needs authentication

User Name

If the proxy requires authentication, enter the user name for the proxy login.

i_round_redOnly basic authentication is available. Enter a string.

Password

This setting is only visible if you select Web page needs authentication above. Enter a password.

Authentication Method

This setting is only visible if you select Web page needs authentication above. Select the authentication method that the URL uses:

  • HTTP authentication: Use simple HTTP authentication.
    i_round_redThis authentication method transmits credentials as plain text.
  • NT LAN Manager authentication: Use the Microsoft NT LAN Manager (NTLM) protocol for authentication.
  • Digest access authentication: Use digest access authentication. This applies a hash function to the password, which is safer than HTTP authentication.

Sensor Display

Sensor Display

Sensor Display

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.

i_round_blueYou can set a different primary channel later by clicking b_channel_primary 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.
    i_round_redYou 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.

Inherited Settings

By default, all of these 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 b_inherited_enabled under the corresponding setting name to disable the inheritance and to display its options.

i_square_cyanFor more information, see section Inheritance of Settings.

Proxy Settings for HTTP Sensors

The proxy settings determine how a sensor connects to a URL. You can enter data for an HTTP proxy server that sensors use when they connect via HTTP or HTTPS.

i_round_blueThis setting only applies to HTTP sensors and how they monitor. To change the proxy settings for the PRTG core server, see section Core & Probes.

Proxy Settings for HTTP Sensors

Proxy Settings for HTTP Sensors

i_square_cyanFor more information, see section Root Group Settings, section Proxy Settings for HTTP Sensors.

Scanning Interval

Scanning Interval

Scanning Interval

i_square_cyanFor more information, see section Root Group Settings, section Scanning Interval.

Schedules, Dependencies, and Maintenance Window

i_round_blueYou 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

Schedules, Dependencies, and Maintenance Window

i_square_cyanFor more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.

Access Rights

Access Rights

Access Rights

i_square_cyanFor more information, see section Root Group Settings, section Access Rights.

Example

i_speechFor example, consider the URL http://www.example.com/status.html that returns a PHP script with the current system status in a simple HTML page as follows:
 

<html>
<body>
 Description: Script gives back current status of disk free (%) and CPU usage (%).
 [85.5][12.0]
</body>
</html>

You would configure the HTTP Content sensor using

  • the Script URL from above,
  • the value type Float,
  • and the number of channels 2.

The sensor calls the URL with every scanning interval and only regards the two values in brackets [ ] and handles each of them in one channel. The additional description text and HTML tags are not necessary. In this example, they are added in case a human calls the URL.

i_round_blueIf you define the number of channels as 1, the sensor only reads the first value. The second value is ignored. Using 3 as the number of channels results in a sensor error message.

Smart URL Replacement

Instead of entering a complete address in the URL field of an HTTP sensor, you can only enter the protocol followed by a colon and three forward slashes (this means that you can enter either http:/// or https:///, or even a simple forward slash / as the equivalent for http:///). PRTG automatically fills in the parent device's IP Address/DNS Name in front of the third forward slash.

Whether this results in a valid URL or not depends on the IP address or Domain Name System (DNS) name of the parent device. In combination with cloning devices, you can use smart URL replacement to create many similar devices.

For example, if you create a device with the DNS name www.mycompany.com and you add an HTTP sensor to it, you can provide values in the following ways:

  • If you enter https:/// in the URL field, PRTG automatically creates the URL https://www.mycompany.com/
  • If you enter /help in the URL field, PRTG automatically creates and monitor the URL http://www.mycompany.com/help
  • It is also possible to provide a port number in the URL field. It is taken over by the device's DNS name and is internally added, for example, http://:8080/

i_round_redSmart URL replacement does not work for sensors that run on the probe device.

Channel List

i_round_blueWhich channels the sensor actually shows might depend on the target 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.

[Value]

The numeric values that an HTTP request returns in several channels

More

i_square_blueKnowledge Base

How can I monitor internal values of a web application with PRTG?

Which HTTP status code leads to which HTTP sensor status?

What security features does PRTG include?

My HTTP sensors don't work. What can I do?