<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> 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 Hypertext Transfer Protocol (HTTP) URLs. The sensor monitors whether logins or shopping carts work properly. It returns the loading time.

Add Sensor

The Add Sensor dialog appears when adding a new sensor on a device manually. It only shows the setting fields that are imperative for creating the sensor. Therefore, you will not see all setting fields in this dialog. You can change all settings in the sensor's Settings tab later.

Sensor Settings

On the sensor's details page, click on the Settings tab to change settings.

Note: If not set explicitly in a sensor's settings, it will connect to the IP Address or DNS Name defined in the settings of the parent device the sensor is created on.

Basic Sensor Settings

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).

HTTP Specific

Timeout (Sec.)

Enter a timeout in seconds for all HTTP requests. If the complete transaction takes longer than this value the request is aborted and an error message is triggered. The maximum value is 900 seconds (15 minutes).

Single URL Timeout (Sec.)

Enter a timeout in seconds for one single HTTP request. If the reply of any single request takes longer than this value the transaction is aborted and an error message is triggered. The maximum value is 900 seconds (15 minutes).

HTTP Engine

Monitoring Engine

If you encounter unexpected errors with the standard method that is used to monitor an URL, try to use the compatibility mode which is based on .Net (introduced in PRTG v13.x.7). Choose between:

  • Default/High Performance (recommended): This is the default monitoring method for this sensor type.
  • Alternate/Compatibility Mode: Try this method as an alternative for websites that do not work with the default approach. Using the compatibility mode, this sensor will execute an external exe. Thus, this method will need more resources, but it can be helpful in particular cases. Note: If you select the compatibility mode, the options for the SSL method will be slightly different. You can also check for trusted certificates. Please see below.
    Note: When using the Compatibility Mode, Smart URL Replacement will not work, i.e., this sensor does not use the IP Address/DNS value of the parent device automatically then.

SSL Specific

SSL Method

This setting is relevant only when using https in the URL field. We recommend using the default value. If you experience connection problems, please select another SSL method from the list. Choose between:

  • SSL V2
  • SSL V2 or V3: This is the default setting.
  • SSL V3
  • TLS V1

Note: Other TLS versions are not supported.

SSL Specific (when using Compatibility Mode)

SSL Method

When using the compatibility mode, the SSL specific settings are a bit different to the default SSL settings. SSL V2 is not available. You can choose between:

  • SSL V3
  • TLS V1
  • SSL V3 or TLS V1: This is the default setting.

Check SSL Certificates

Specify if the certificate of the monitored URL will be checked. Choose between:

  • Do not check used certificates: This the default setting.
  • Check if the used certificates are trusted: If the certificate of the server is not trusted, the sensor will go into a Down status and display a corresponding message.

Note: This sensor type implicitly supports Server Name Identification (SNI), an extension to the TLS protocol.

Advanced Sensor Data

Limit Download (kb)

Enter a maximum amount of data that will be transferred per every single request. If you set content checks below, please be aware that only the content downloaded within this limit can be checked for certain search expressions.

Cookie Management

Select if cookies will be used for the transaction. Choose between:

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

We recommend using the default value.

Result Handling

Define what will be done with the web page loaded at the given URL. Choose between:

  • Discard HTML result: Do not store the requested web page.
  • Store latest HTML result: Store the last result of the requested web page to the "Logs (Sensors)" directory (on the Master node, if in a cluster). This is for debugging purposes, especially in combination with content checks. The file will be overridden with each scanning interval. For information on how to find the folder used for storage, please see Data Storage section.

Authentication

Authentication

Define if the web page at the configured URL need authentication. Choose between:

  • No authentication needed
  • Web page needs authentication

User

This field is only visible if authentication is enabled above. Enter a username. Please enter a string.

Password

This field is only visible if authentication is enabled above. Enter a password. Please enter a string.

Authentication Method

This field is only visible if authentication is enabled above. Please select the authentication method the given URL is protected with. Choose between:

  • Basic access authentication (HTTP): Use simple HTTP authentication. This is the default setting and suitable for most cases. Note: This authentication method will transmit credentials as plain text!
  • Windows NT LAN Manager (NTLM): Use the Microsoft NTLM protocol for authentication. This is sometimes used in Intranets for single sign-on.

We recommend using the default value.

Transaction URL

You can define up to 10 different transaction URLs which will all be called in a row. Only if the complete transaction can be completed, the sensor will be in an Up status. Using this mechanism you can set up an extended monitoring with multiple URLs. Please enter settings for at least one transaction URL. You can use as many steps as needed and disable the other steps.

Transaction Step #x

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

  • Disable step #x: Do not use this step. Choose this option if you do not need all 10 steps for your transaction check.
  • Enable step #x: Enable this step. Further options will be viewed, as described below.

URL

Please enter the URL the sensor will connect to. It has to be URL encoded! If you enter an absolute URL, this address will be independent from the IP address/DNS name setting of the device this sensor is created on. PRTG uses a smart URL replacement which allows you to use the parent device's IP address/DNS name setting as part of the URL. For more information, please see section Smart URL Replacement below.

Request Method

The request method determines how the given URL is requested.

  • GET: Request the website directly, like browsing the web. We recommend using this setting for a simple check of a web page.
  • POST: Send post form data to the URL. If this setting is chosen, you must enter the data that will be sent in the Postdata field below.
  • HEAD: Only request the HTTP header from the server; without the actual web page. Although this saves bandwidth since less data is transferred, it is not recommended because the measured request time is not the one experienced by your users and you might not be notified for slow results or timeouts.

Postdata

This field is only active when POST is selected in the Request Method setting above. Please enter the data part for the post request here. Note: No XML is allowed here!

Check For Existing Key Words (Positive)

Define whether the result at the configured URL will be checked for keywords. Choose between:

  • Disable: Do not search for keywords.
  • Enable key word check (positive): In the result returned at the URL, check if a key word exists.

Note: The content check is only intended for html websites and might not work with other target URLs.

Response Must Include

Define which string must be part of the web at the given URL. If the data does not include this string, the sensor will be set to an error state. Please enter a string. Note: Only simple text search is available here. 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.

Check For Existing Key Words (Negative)

Define whether the the result at the configured URL will be checked for keywords. Choose between:

  • Disable: Do not search for keywords.
  • Enable key word check (negative): In the result returned at the URL, check if a key word does not exist.

Note: The content check is only intended for html websites and might not work with other target URLs.

Response Must Not Include

Define which string must not be part of the web at the given URL. If the data does include this string, the sensor will be set to an error state. Please enter a string. Note: Only simple text search is available here. 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.

Inherited Settings

By default, all following settings are inherited from objects higher in the hierarchy and should be changed there, if necessary. Often, best practice is to change them centrally in the Root group's settings. To change a setting for this object, disable inheritance by clicking on the check mark symbol in front of the respective setting name. You will then see the options described below.

Proxy Settings for HTTP Sensors

HTTP Proxy Settings

The proxy settings determine how a sensor connects to a given URL. You can enter data for a proxy server that will be used when connecting via HTTP or HTTPS. Note: This setting is valid for the monitoring only and determines the behavior of sensors. In order to change proxy settings for the core server, please see System Administration—Core & Probes.

Name

Enter the IP address or DNS name of the proxy server to use. If you leave this field empty, no proxy will be used.

Port

Enter the port number of the proxy. Often, port 8080 is used. Please enter an integer value.

User

If the proxy requires authentication, enter the username for the proxy login. Note: Only basic authentication is available! Please enter a string or leave the field empty.

Password

If the proxy requires authentication, enter the password for the proxy login. Note: Only basic authentication is available! Please enter a string or leave the field empty.

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.

When a Sensor Reports an Error

With this setting, you can define the number of scanning intervals a sensor has to report an error until the sensor will be set to a Down status. The sensor can try reaching a device several times, depending on your setup you can specify here, to help avoid false alarms if the monitored device has only temporary issues. For previous scanning intervals with failed requests, the sensor will show a Warning status. Choose between:

  • Set sensor to "down" immediately: The sensor will show an error after the first failed request.
  • Set sensor to "warning" for 1 interval, then set to "down" (recommended): After the first failed request, the sensor will show a yellow warning status. If the following request also fails, the sensor will show an error.
  • Set sensor to "warning" for 2 intervals, then set to "down": The sensor will only show an error status after three failed requests in a row.
  • Set sensor to "warning" for 3 intervals, then set to "down": The sensor will only show an error status after four failed requests in a row.
  • Set sensor to "warning" for 4 intervals, then set to "down": The sensor will only show an error status after five failed requests in a row.
  • Set sensor to "warning" for 5 intervals, then set to "down": The sensor will only show an error status after six failed requests in a row.

Note: Sensors that monitor via Windows Management Instrumentation (WMI) will always wait at least one scanning interval until an error is shown. It is not possible to set a WMI sensor "down" immediately, so the first option will not apply to these sensor types (all other options can apply).

Note: If a sensor has defined error limits for channels, this sensor will always be set to a Down status immediately, so no "wait" option will apply.

Schedules, Dependencies, and Maintenance Window

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 monitor for a certain time span (days, hours) throughout the week. With the period list option it is also possible to pause monitoring for a specific time span. 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. You can check all dependencies in your PRTG installation by selecting Devices | Dependencies from the main menu bar.

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.

For more details about access rights, please see section User Access Rights.

Smart URL Replacement

Instead of entering a complete address in the URL field of an HTTP sensor, you can merely enter the protocol followed by colon and three slashes (that means you can enter either http:/// or https:/// or even a simple slash / as equivalent for http:///). PRTG will then fill in the parent device's IP address or DNS name in front of the third slash automatically. Whether this results in a valid URL or not, depends on the IP address or DNS name of the device where this HTTP sensor is created on. In combination with cloning devices, the smart URL replacement makes it easy to create many like devices.

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

  • Providing the value https:/// in the URL field, PRTG will automatically create the URL https://www.example.com/ from that.
  • Using the value /help in the URL field, PRTG will automatically create and monitor the URL http://www.example.com/help
  • It is also possible to provide a port number in the URL field which will be taken over by the device's DNS name and internally added, for example, http://:8080/

Note: Smart URL replacement does not work for sensors running on the "Probe Device".

More

Knowledge Base: Configuration Tips for HTTP Transaction Sensors needed

Edit Sensor Channels

In order to change display settings, spike filter, and limits, please switch to the sensor's Overview tab and click on the gear icon of a specific channel. For detailed information, please see Sensor Channels Settings section.

Notifications

Click on the Notifications tab to change notification triggers. For detailed information, please see Sensor Notifications Settings section.

Others

For more general information about settings, please see Object Settings section.

Sensor Settings Overview

For information about sensor settings, please see the following sections:

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