PRTG Manual: HTTP Sensor

PRTG Manual: HTTP Sensor

The HTTP sensor monitors a web server using Hypertext Transfer Protocol (HTTP). It shows the loading time. This is the easiest way to monitor if a website (or a specific website element) is reachable.

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 the HTTP request. If the reply takes longer than this value the request is aborted and an error message is triggered.
URL	Please enter the URL the sensor will connect to. This address can be independent from the IP address/DNS name setting of the device this sensor is created on. You can enter an URL leading to a webpage (to measure the page source code's loading time), or enter the URL of an image or of another page asset to measure this element's availability and loading time. PRTG uses a smart URL replacements 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!
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 drop down menu. Choose between: SSL V2 SSL V2 or V3: This is the default setting. SSL V3 TLS V1

Sensor Display
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 will always be displayed underneath the sensor's name. The available options depend on what channels are available for this sensor.
Chart Type	Define how different channels will be shown for this sensor. Show channels independently (default): Show an own 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 will generate an easy-to-read graph which visualizes the different components of your total traffic. Note: This option cannot be used in combination with manual Vertical Axis Scaling (available in the Sensor Channels Settings settings).
Stack Unit	This setting is only available if stacked graphs are selected above. Choose a unit from the list. All channels with this unit will be 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 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.

HTTP Proxy Settings
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.
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.

Schedules and Dependencies
Schedule	Select a schedule from the list. Schedules can be used to pause monitoring for a certain time span (days, hours) throughout the week. 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.
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.
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.

Inherit 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.

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 a HTTP sensor on it with the value https:/// in the URL field, PRTG will automatically create the URL https://www.example.com/ from that. Similarly, if you create a HTTP sensor on the same device using the value /help in the URL field, PRTG will automatically create and monitor the URL http://www.example.com/help

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

Channels

Click on the Channels tab to change display settings, spike filter, and limits. 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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