PRTG Manual: HTTP SSL Certificate Expiry Sensor

This Sensor Type Is Deprecated!

This sensor type is deprecated. We provide the documentation in this section for your information only. We removed this sensor type from PRTG with version 16.x.25 (expected in May 2016). Your sensor will then stop monitoring and show a Down status.

See the following article for details and possible alternatives for deprecated sensors:

Knowledge Base: The PRTG Sensor Cleanup

Alternative Sensor Type

Please use the SSL Certificate Sensor instead.

The HTTP SSL Certificate Expiry Sensor checks a specific HTTPS URL and returns the number of days remaining until the site's Secure Sockets Layer (SSL) certificate expires. It shows a Warning when only 60 days are left, and a Down status when only 30 days are remaining until the certificate expires. The sensor reports an error if the certificate is revoked.

  • The sensor shows the number of days until the expiry of the certificate.
HTTP SSL Certificate Expiry Sensor

HTTP SSL Certificate Expiry Sensor

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

Remarks

  • Requires .NET 4.0 or higher on the probe system. Note: If the sensor shows the error PE087, additionally install .NET 3.5 on the probe system.
  • Note: It might be necessary to run the PRTG probe service with administrative rights if this sensor does not work (it might show a timeout error with code PE018 without according rights).
  • Note: This sensor type might not work on probes running on Windows Server 2003 (including SP1 and SP2).
  • We recommend Windows 2012 R2 on the probe system for best performance of this sensor.
  • Knowledge Base: My HTTP sensors could not create an SSL secure channel and are down. What can I do?
  • Knowledge Base: Which HTTP status code leads to which HTTP sensor status?
  • This sensor does not support Secure Remote Password (SRP) ciphers.
  • This sensor can have a high impact on the performance of your monitoring system. Use it with care. We recommend that you use no more than 50 sensors of this sensor type on each probe.

Requirement: .NET Framework

This sensor type requires the Microsoft .NET Framework to be installed on the probe system (on every cluster node, if on a cluster probe). If the framework is missing, you cannot create this sensor.

Required .NET version (with latest updates): .NET 4.0 (Client Profile is sufficient), .NET 4.5, or .NET 4.6.

i_square_cyanFor more information, see the Knowledge Base: Which .NET version does PRTG require?

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 do not see all setting fields in this dialog. You can change (nearly) all settings in the sensor's Settings tab later.

Sensor Settings

Click the Settings tab of a sensor to change its settings.

i_round_blueUsually, a sensor connects to the IP Address or DNS Name of the parent device on which you created the sensor. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings. See below for details on available settings.

Setting

Description

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. 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. You can add additional tags to the sensor. There are default tags that are automatically predefined in a sensor's settings when you add a sensor.

i_round_blueIt is not possible to enter tags with a leading plus (+) or minus (-) sign, nor tags with parentheses (()) or angle brackets (<>).

Priority

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

Sensor Settings

URL

Enter the absolute URL to check for the SSL certificate (this sensor does not use the IP Address/DNS Name of the parent device). It has to be URL encoded.

SSL Connection

Define the encryption of the connection to the URL configured above:

  • Use TLS (recommended): The sensor tries to connect via Transport Layer Security (TLS). If this does not work, the sensor shows a Down status.
  • Use SSLv3 if available (not recommended): The sensor tries to connect via TLS or SSL and determines the correct encryption automatically.
  • Force usage of SSLv3 (not recommended): The connection must be established using SSLv3. Otherwise, the sensor shows a Down status.
    Note: The force SSLv3 method does not work when the requested URL uses forward secrecy. See section More.

Certificate Name Validation

Define if you want to check if the defined URL matches the certificate:

  • The certificate must match the DNS name: The sensor compares the certificate and the Domain Name System (DNS) name. If they do not match, the sensor shows a Down status.
  • Accept any certificate: The sensor does not compare the certificate and the DNS name.

Debug Options

Setting

Description

Sensor Result

Define what PRTG does with the sensor results:

  • Discard sensor result: Do not store the sensor result.
  • Write sensor result to disk (file name: Result of Sensor [ID].txt): Store the last result received from the sensor to the \Logs\sensors subfolder of the PRTG data directory on the probe system (master node, if in a cluster). File names: Result of Sensor [ID].txt and Result of Sensor [ID].Data.txt. This is for debugging purposes. PRTG overwrites these files with each scanning interval.
    i_podThis option is not available when the sensor runs on the hosted probe of a PRTG hosted by Paessler instance.

Proxy Settings for HTTP Sensors

Click b_inherited_enabled to interrupt the inheritance. See section Inheritance of Settings for more information.

The proxy settings determine how a sensor connects to a URL. You can enter data for an HTTP proxy server that sensors use when connecting via HTTP or HTTPS.

i_round_blueThis setting only affects monitoring and it determines the behavior of HTTP sensors. To change proxy settings for the PRTG core server, see section System Administration—Core & Probes.

i_round_blueThe SSL Certificate sensor and the SSL Security Check sensor do not support HTTP proxies but you can configure connections via SOCKS proxies in the sensors' settings.

Setting

Description

Name

Enter the IP address or Domain Name System (DNS) name of the proxy server. If you leave this field empty, no proxy is used.

Port

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

User

If the proxy requires authentication, enter the username for the proxy login.

i_round_redOnly basic authentication is available. Enter a string or leave the field empty.

Password

If the proxy requires authentication, enter the password for the proxy login.

i_round_redOnly basic authentication is available. Enter a string or leave the field empty.

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 the pin symbol of a channel 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_blueThis option cannot be used in combination with manual Vertical Axis Scaling (available in the channel settings).

Stack Unit

This field 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 the following settings are inherited from objects that are higher in the hierarchy and should be changed there if necessary. Often, best practice is to change them centrally in the root group settings. For more information, see section Inheritance of Settings. To change a setting for this object only, disable inheritance by clicking the button next to inherit from under the corresponding setting name. You then see the options described below.

Scanning Interval

Click b_inherited_enabled to interrupt the inheritance. See section Inheritance of Settings for more information.

Setting

Description

Scanning Interval

Select a scanning interval (seconds, minutes, or hours). The scanning interval determines the amount of time that 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 the sensor has time to reach and check a device again in case a sensor query fails. Depending on the option that you select, the sensor can try to reach and check a device again several times before the sensor shows a Down status. This can avoid false alarms if the monitored device only has temporary issues. For previous scanning intervals with failed requests, the sensor shows a Warning status. Choose from:

  • Set sensor to down immediately: Set the sensor to a Down status immediately after the first failed request.
  • Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to a Warning status after the first failed request. If the following request also fails, the sensor shows an error.
  • Set sensor to warning for 2 intervals, then set to down: Set the sensor to a Down status only after three consecutively failed requests.
  • Set sensor to warning for 3 intervals, then set to down: Set the sensor to a Down status only after four consecutively failed requests.
  • Set sensor to warning for 4 intervals, then set to down: Set the sensor to a Down status only after five consecutively failed requests.
  • Set sensor to warning for 5 intervals, then set to down: Set the sensor to a Down status only after six consecutively failed requests.

i_round_blueSensors that monitor via Windows Management Instrumentation (WMI) always wait at least one scanning interval before they show a Down status. It is not possible to immediately set a WMI sensor to a Down status, so the first option does not apply to these sensors. All other options can apply.

i_round_blueIf you define error limits for a sensor's channels, the sensor immediately shows a Down status. No "wait" option applies.

i_round_blueIf a channel uses lookup values, the sensor immediately shows a Down status. No "wait" options apply.

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 settings here. They are active at the same time as the parent objects' settings.

Setting

Description

Schedule

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

i_square_cyanYou can create schedules, edit schedules, or pause monitoring for a specific time span. For more information, see section Account Settings—Schedules.

i_round_blueSchedules are generally inherited. New schedules are added to schedules that you already set up, 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, the selected object and all child objects are not monitored. They are in a Paused status instead. Choose between:

  • Not set (monitor continuously): No maintenance window is set and monitoring is always 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 an active maintenance window.

i_round_blueTo terminate an active maintenance window before the defined end date, change the time entry in Maintenance Ends to a date in the past.

Maintenance Begins

This field is only visible if you enable Set up a one-time 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 enable Set up a one-time 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. You can use dependencies to pause monitoring for an object depending on the status of a different object. You can choose from:

  • Use parent: Use the dependency type of the parent object.
  • Select a sensor: Use the dependency type of the parent object. Additionally, pause the current object if a specific sensor is in a Down status or in a Paused status caused by another dependency.
  • Master sensor for parent: Make this sensor the master object for its parent device. The sensor influences the behavior of its parent device: If the sensor is in a Down status, the device is 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 is paused if the parent group is paused by another dependency.

i_round_blueTo test your dependencies, select Simulate Error Status from the context menu of an object that other objects depend on. A few seconds later, all dependent objects are paused. You can check all dependencies under Devices | Dependencies in the main menu bar.

Dependency

This field is only visible if you enable Select a sensor above. Click the Search button and use the object selector to select a sensor on which the current object will depend.

Dependency Delay (Sec.)

This field is only visible if you enable Select a sensor above. Define a time span in seconds for dependency delay.

After the master sensor for this dependency comes back to an Up status, monitoring of the dependent objects is additionally delayed by the defined time span. This can prevent false alarms, for example, after a server restart, by giving systems more time for all services to start up. Enter an integer value.

i_round_redThis setting is not available if you set this sensor to Use parent or to be the Master sensor for parent. In this case, define delays in the parent device settings or in its parent group settings.

Access Rights

Click b_inherited_enabled to interrupt the inheritance. See section Inheritance of Settings for more information.

Setting

Description

User Group Access

Define the user groups that have access to the object. You see a table with user groups and group access rights. The table contains all user groups in your setup. For each user group, you can choose from the following group access rights:

  • Inherited: Inherit the access rights settings of the parent object.
  • No access: Users in this user group cannot see or edit the object. The object neither shows up in lists nor in the device tree.
    i_round_blueThere is one exception: If a user in this user group has access to a child object, the parent object is visible in the device tree but users in this user group cannot access it.
  • Read access: Users in this group can see the object and view its monitoring results. They cannot edit any settings.
  • Write access: Users in this group can see the object, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
  • Full access: Users in this group can see the object, view its monitoring results, edit its settings, and edit its access rights settings.

To automatically set all child objects to inherit this object's access rights, enable the Revert children's access rights to inherited option.

i_square_cyanFor more details on access rights, see section Access Rights Management.

More

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

Knowledge Base: My HTTP sensors could not create an SSL secure channel and are down. What can I do?

Knowledge Base: For which sensor types do you recommend Windows Server 2012 R2 and why?

Knowledge Base: Which .NET version does PRTG require?

Edit Channels

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

Notification Triggers

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

Others

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

Sensor Settings Overview

For information about sensor settings, see the following sections: