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Aurelio, System Admin at Paessler AG

The HTTP Apache ModStatus Totals sensor monitors the activity of an Apache web server using mod_status over Hypertext Transfer Protocol (HTTP).

It can show the following:

  • Number of accesses
  • Transferred data in kilobytes per second

Which channels the sensor actually shows might depend on the monitored device and the sensor setup.

HTTP Apache ModStatus Totals SensorHTTP Apache ModStatus Totals Sensor

Click here to enlarge: http://media.paessler.com/prtg-screenshots/http_apache_modstatus_totals.png

Remarks

Add Sensor

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

Sensor Settings

On the details page of a sensor, click the Settings tab to change its settings.

icon-i-roundUsually, a sensor connects to the IP Address or DNS Name of the parent device where you created this sensor. See the Device Settings for details. For some sensor types, you can define the monitoring target explicitly in the sensor settings. Please see below for details on available settings.

Basic Sensor Settings

Sensor Name

Enter a meaningful name to identify the sensor. By default, PRTG shows this name in the device tree, as well as in alarms, logs, notifications, reports, maps, libraries, and tickets.

Parent Tags

Shows Tags that this sensor inherits from its parent device, group, and probe. This setting is shown for your information only and cannot be changed here.

Tags

Enter one or more Tags , separated by spaces or commas. You can use tags to group sensors and use tag–filtered views later on. Tags are not case sensitive. We recommend that you use the default value.

You can add additional tags to the sensor if you like. Other tags are automatically inherited from objects further up in the device tree. These are visible above as Parent Tags .

Priority

Select a priority for the sensor. This setting determines where the sensor is placed in sensor lists. Top priority is at the top of a list. Choose from one star (low priority) to five stars (top priority).

HTTP Specific

Timeout (Sec.)

Enter a timeout in seconds for the request. If the reply takes longer than this value defines, the sensor will cancel the request and show a corresponding error message. Please enter an integer value. The maximum value is 900 seconds (15 minutes).

URL

Enter the URL to the mod_status module on your Apache server. PRTG will append a /server_status?auto part automatically. 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.

icon-i-roundPRTG 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.

icon-i-roundThis sensor type implicitly supports Server Name Identification (SNI), an extension to the TLS protocol.

Authentication

Authentication

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

  • No authentication needed
  • Web page needs authentication

User

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

Password

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

Authentication Method

This field is only visible if enable authentication above. 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.
    icon-i-round-redThis authentication method transmits 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.
  • Digest Access Authentication : Use digest access authentication that applies a hash function to the password which is safer than basic access authentication.

We recommend that you use the default value.

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 below the sensor's name. The available options depend on what channels are available for this sensor.

icon-i-roundYou can set another primary channel later by clicking the pin symbol of a channel in the sensor's Overview tab.

Graph 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 that visualizes the different components of your total traffic.
    icon-i-roundThis 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 only for this object, disable inheritance by clicking the check mark in front of the corresponding 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 an HTTP proxy server that sensors will use when connecting via HTTP or HTTPS.

icon-i-roundThis setting affects monitoring only and determines the behavior of HTTP sensors. To change proxy settings for the core server, please see System Administration—Core & Probes .

icon-i-roundThe SSL Certificate Sensor and the SSL Security Check Sensor do not support HTTP proxies, but you can configure connections via SOCKS proxies in their sensor settings.

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.

icon-i-round-redOnly 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.

icon-i-round-redOnly basic authentication is available! Please enter a string or leave the field empty.

Scanning Interval

Scanning Interval

Select a scanning interval (seconds, minutes, or hours) from the list. The scanning interval determines the time the sensor waits between two scans. You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Define the number of scanning intervals that a sensor has time reach and check a device again in case a sensor query fails. The sensor can try to re-reach and check a device several times, depending on the option you select here, before it will be set to a Down status. This helps you 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 immediately 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" : Show an error status only after three continuously failed requests.
  • Set sensor to "warning" for 3 intervals, then set to "down" : Show an error status only after four continuously failed requests.
  • Set sensor to "warning" for 4 intervals, then set to "down" : Show an error status only after five continuously failed requests.
  • Set sensor to "warning" for 5 intervals, then set to "down" : Show an error status only after six continuously failed requests.

icon-i-roundSensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval until they show an error. It is not possible to set a WMI sensor to "down" immediately, so the first option will not apply to these sensor types. All other options can apply.

icon-i-roundIf a sensor has defined error limits for channels, it will always show a Down status immediately, so no "wait" option will apply.
 

icon-i-roundIf a channel uses lookup values, it will always show a Down status immediately, so no "wait" options will apply.

Schedules, Dependencies, and Maintenance Window

icon-i-roundInheritance for schedules, dependencies, and maintenance windows cannot be interrupted. The corresponding settings from the parent objects will always be active. However, you can define additional settings here. They will be active at the same time as the parent objects' settings.

Schedule

Select a schedule from the list. Schedules can be used to monitor for a certain time span (days, hours) every 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.

icon-i-roundSchedules are generally inherited. New schedules will be added to existing ones, so all schedules are active at the same time.

Maintenance Window

Specify if you want to set up a one-time maintenance window. During a "maintenance window" period, this object and all child objects will not be monitored. They will be in a paused state instead. Choose between:

  • Not set (monitor continuously) : No maintenance window will be set and monitoring will always be active.
  • Set up a one-time maintenance window : Pause monitoring within a maintenance window. You can define a time span for a monitoring pause below and change it even for a currently running maintenance window.

icon-i-roundTo terminate a current maintenance window before the defined end date, change the time entry in Maintenance Ends field to a date in the past.

Maintenance Begins

This field is only visible if you enabled the maintenance window above. Use the date time picker to enter the start date and time of the maintenance window.

Maintenance Ends

This field is only visible if you enabled the maintenance window 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, where it is created on, is in Down status, or is paused by another dependency.
  • Select object : Pause the current sensor if the device, where it is created on, is in Down status, or is paused by another dependency. Additionally, pause the current sensor if a specific other object in the device tree is in Down status, or 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, where it is created on: If the sensor is in 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 Down status, or if it is paused by another dependency.

icon-i-roundTesting 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-glasses and use the object selector to choose an object on which the current sensor will depend.

Dependency Delay (Sec.)

Define a time span in seconds for a dependency delay. After the master object for this dependency goes back to Up status, PRTG will start monitoring the depending objects after this extra delayed. This can help to 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.

icon-i-round-redThis setting is not available if you choose this sensor to Use parent or to be the Master object for parent . In this case, please define delays in the parent Device Settings or in 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 types of access rights 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 access rights settings of the parent object.
  • None : Users in this group cannot see or edit the object. The object neither shows up in lists nor 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.

icon-book-arrowsFor more details on access rights, please see the 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 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 add an HTTP sensor to 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/
  • 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/

icon-i-round-redSmart URL replacement does not work for sensors running on the Probe Device .

More

Knowledge Base: Which HTTP status code leads to which HTTP sensor status?

Edit Sensor Channels

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

Notifications

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

Others

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

Sensor Settings Overview

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