PRTG Manual: HTTP Data Advanced Sensor

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.

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:

• 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 () to the highest priority ().

Timeout (Sec.)

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

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

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. You can enter the URL of a web page (to measure the loading time of the page's source code), or enter the URL of an image or of a page asset to measure this element's availability and loading time.

The URL must be URL encoded.

If you monitor an image or a page asset, this can create a high amount of memory load. We recommend that the size of the elements that you want to monitor does not exceed 200 MB.

PRTG 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.

Request Method

Select an HTTP request method to determine how the sensor requests the URL:

• GET: Directly request the website.
  We recommend that you use this setting for a simple check of the web page.
• POST: Send post form data to the URL.
  If you select this setting, you must enter the data in the Postdata field below.
• HEAD: Only request the HTTP header from the server without the actual web page.
  Although this saves bandwidth because it transfers less data, we do not recommended that you use this. This is because the measured request time is not the one that your users experience and you might not be notified of slow results or timeouts.

Postdata

This setting is only visible if you select POST above. Enter the data part for the POST request.

No Extensible Markup Language (XML) is allowed here.

Content Type

This setting is only visible if you select POST above. Define the content type of the POST request:

• Default (application/x-www-form-urlencoded): Use the default content type to encode the form data set for submission to the server.
• Custom: Use a custom content type. Enter the content type below.

Custom Content Type

This setting is only visible if you select Custom above. Define the custom content type, for example, XML, JavaScript Object Notation (JSON), or HTTP.

Server Name Indication

Shows the Server Name Indication (SNI) that the sensor automatically determines from the host address of the parent device or from the target URL of the sensor.
The SNI must be a fully qualified domain name (FQDN). Make sure that it matches the configuration of the target server.

For details, see the Knowledge Base: My HTTP sensors fail to monitor websites which use SNI. What can I do?

SNI Inheritance

Define if you want to inherit the SNI from the parent device:

• Inherit SNI from parent device: Determine the SNI from the host address of the parent device.
• Do not inherit SNI from parent device: Determine the SNI from the target URL as defined in the settings of this sensor.

Result Handling

Define what the sensor does with the data loaded at the URL:

• Discard result: Do not store the sensor result.

• Store result: Store the last result of the requested data in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID].txt, Result of Sensor [ID]-A.txt, and Result of Sensor [ID].Data.txt. This setting is for debugging purposes, especially in combination with content checks. PRTG overwrites these files with each scanning interval.

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

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

HTTP Version

Define the HTTP version that the sensor uses when it connects to the target URL:

• HTTP 1.0: Use HTTP version 1.0.
• HTTP 1.1: Use HTTP version 1.1.

User Agent

Choose which user agent string the sensor sends when it connects to the target URL:

• Use the default string: Do not enter a specific user agent and use the default string. Usually, this is Mozilla/5.0 (compatible; PRTG Network Monitor (www.paessler.com); Windows).
• Use a custom string: Use a custom user agent. Define the custom user agent below.

Custom User Agent

This setting is only visible if you enable Use a custom string above. Enter the string that the sensor uses as the user agent when it connects to the target URL.

HTTP Headers

Define if you want to send custom HTTP headers to the target URL:

• Do not use custom HTTP headers: Do not use custom HTTP headers.
• Use custom HTTP headers: Use custom headers. Define below.

Custom HTTP Headers

This setting is only visible if you enable Use custom HTTP headers above. Enter a list of custom HTTP headers and values that you want to transmit to the URL, each pair in one line. The syntax of a header-value pair is header1:value1

The sensor does not support the header field names user-agent, content-length, and host.

Ensure that the HTTP header statement is valid. Otherwise, the sensor request cannot be successful.

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.

Only 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.
  This 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.

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 in percent.

[Value]

The values that the web server returns in several channels

This channel is the primary channel by default.

For details about the return value format, see section Custom Sensors.