PRTG Manual: HTTP Transaction Sensor

The HTTP Transaction sensor monitors an interactive website, such as a web shop, by performing a transaction using a set of HTTP URLs. The sensor monitors whether logins or shopping carts work properly.

HTTP Transaction Sensor

HTTP Transaction 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 (Transactie)
  • French: Transaction (HTTP)
  • German: HTTP (Transaktion)
  • Japanese: HTTP トランザクション
  • Portuguese: Transação HTTP
  • Russian: Транзакция HTTP
  • Simplified Chinese: HTTP 处理
  • Spanish: Transacción HTTP

Remarks

  • This sensor has a high performance impact. Use it with care. We recommend that you use no more than 200 sensors of this sensor type on each probe.

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.

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:

  • httptransactionsensor

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).

HTTP Specific

HTTP Specific

HTTP Specific

Setting

Description

Timeout (Sec.)

Enter a timeout in seconds for all HTTP requests. Enter an integer. The maximum value is 900 seconds (15 minutes).

i_round_blueIf the complete transaction takes longer than this value, the sensor cancels the request and shows an according error message. If two consecutive requests are unsuccessful (for whatever reason), the sensor shows the Down status.

Single URL Timeout (Sec.)

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

i_round_blueIf the reply of any single request takes longer than this value, the sensor cancels the transaction and shows an according error message.

Monitoring Engine

Monitoring Engine

Monitoring Engine

Setting

Description

Monitoring Engine

Choose the monitoring engine that the sensor uses:

  • Default engine (recommended): Use the default monitoring engine.
  • Compatibility engine: Execute an external executable program. Use this method as an alternative for websites that do not work with the default monitoring engine.
    i_round_blueThis method needs more resources but it can be helpful in some cases.
    i_round_blueIf you select the compatibility mode, the options for the SSL method are different. You can also check for trusted certificates. See below.
    i_round_redSmart URL Replacement does not work with the compatibility mode, so this sensor does not automatically use the IP Address/DNS Name of the parent device.

SSL/TLS Method

This option is only visible if you select Compatibility engine above. Choose from:

  • SSLv3
  • TLS 1.0, TLS 1.1, TLS 1.2
  • SSLv3, TLS 1.0, TLS 1.1, TLS 1.2 (default)

Check SSL Certificates

This option is only visible if you select Compatibility engine above. Specify if the sensor checks the certificate of the URL:

  • Do not check certificates: Do not check the certificates of the web pages. This is the default setting.
  • Check if certificates are trusted: Check the certificates of the web pages. If the certificate of the server is not trusted, the sensor shows the Down status and displays a corresponding message.

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

Download Limit (KB)

Enter a number that defines the maximum amount of data (in kilobytes) that the sensor transfers per request.

i_round_redIf you set content checks, be aware that they might be incomplete. This is because the sensor only checks the content that is downloaded up to this limit for search expressions.

Cookie Management

Select if you want to allow cookies for the transaction:

  • Use cookies (recommended): Allow cookies to be set and read during the transaction cycle. We recommend that you use this option.
  • Ignore cookies: Do not allow cookies. Use this option if you want to test the transaction without the use of cookies.

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.

Result Handling

Define what PRTG does with the web page that is loaded at the URL:

  • Discard result: Do not store the sensor result.
  • Store result: Store the last result of the web page in the \Logs\sensors subfolder of the PRTG data directory on the probe system. The file names are Result of Sensor [ID]-1.txt and Result of Sensor [ID].Data.txt. This setting is for debugging purposes, especially in combination with content checks. PRTG overwrites the 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.

Transaction URL

You can define up to 10 different transaction URLs, which are all called in a row. If the transaction can be completed, the sensor shows the Up status. Using this mechanism, you can set up extended monitoring with multiple URLs.

Enter settings for at least one transaction URL. You can use as many steps as necessary and disable the other steps.

Transaction URL #x

Transaction URL #x

Setting

Description

Transaction Step #x

This setting is available for URL #2 through #10. Define if you want to use this step for the transaction check:

  • Disable step #x: Do not use this step. Choose this option if you do not need all 10 steps for the transaction check.
  • Enable step #x: Enable this step. Further options are available.

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 not 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.

Request Method

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

  • GET: Directly request the website.
    i_round_blueWe recommend that you use this setting for a simple check of the web page.
  • POST: Send post form data to the URL.
    i_round_redIf 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.
    i_round_blueAlthough 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.

i_round_redNo Extensible Markup Language (XML) is allowed here.

Require Keyword

Define if the sensor checks the result at the URL for keywords:

  • Do not check for keyword (default): Do not search for keywords in the result.
  • Set sensor to warning status if keyword is missing: Check if a keyword exists in the result. If it exists, set the sensor to the Warning status.
  • Set sensor to down status if keyword is missing: Check if a keyword exists in the result. If it exists, set the sensor to the Down status.

i_round_blueThe content check is only intended for HTML websites and might not work with other target URLs.

Response Must Include

This setting is only visible if you select Set sensor to warning status if keyword is missing or Set sensor to down status if keyword is missing above. Define the search string that must be part of the result at the URL.

i_round_blueIf the result at the URL does not include the search pattern, the sensor shows the status defined above and displays this string along with the affected URL in the sensor message.

i_round_blueOnly simple text search is available here.

i_round_blueThe 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 not possible.

Exclude Keyword

Define if the sensor checks the result at the URL for keywords:

  • Do not check for keyword (default): Do not search for keywords in the result.
  • Set sensor to warning status if keyword is found: Check if a keyword exists in the result. If it exists, set the sensor to the Warning status.
  • Set sensor to down status if keyword is found: Check if a keyword exists in the result. If it exists, set the sensor to the Down status.

i_round_blueThe content check is only intended for HTML websites and might not work with other target URLs.

Response Must Not Include

Define a string that must not be part of the result at the URL. If the data includes this string, the sensor shows the Down status and displays this string along with the affected URL in the sensor message. Enter a string.

i_round_blueOnly simple text search is available here.

i_round_blueThe 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 not possible.

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.

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.

Sum

The loading time of the complete transaction in milliseconds (msec)

i_round_blueThis channel is the primary channel by default.

Time of URL [#]

The loading time of single URLs in msec

More

i_square_blueKnowledge Base

Configuration tips for HTTP Transaction sensors needed

Which user agent should I use in the HTTP Advanced sensor's settings?

What security features does PRTG include?

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