PRTG Manual: Port Sensor

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 the sensor inherits from its parent device, parent group, and parent 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.

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

The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:

• portsensor

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 () to the highest priority ().

Timeout (Sec.)

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

Port

Enter the number of the port to which this sensor connects. Enter an integer value.

Transport-Level Security

Define the security of the connection:

• Use transport-level security (default): Establish the connection with the strongest Secure Sockets Layer (SSL)/Transport Layer Security (TLS) method that the target device provides.
• Do not use transport-level security: Establish the connection without connection security.

Goal

Define how the sensor reports on the port:

• Open: Show the Up status if the port is open, and the Down status if the port is closed.
• Closed: Show the Up status if the port is closed, and the Down status if the port is open.

Command

Define whether the sensor sends a command after opening the port:

• Don't send command: Only check if a connection to the port is possible.
• Send command: Open a Telnet session to the respective port and send the command.
  You cannot use this option if the target machine is a web server.

Command

This setting is only visible if you enable Send command above. Enter a command that the sensor sends to the respective port in a Telnet session. You cannot use line breaks, only a simple Telnet command in a single line. Enter a string.

Response

Define if the sensor further processes the received response:

• Ignore response: Do not check the response.
• Check response code (integer): Check if the response matches a defined response code. Define the response code below.
• Check response text: Check if the response matches a defined response text. Define the response text below.

Allowed Code

This setting is only visible if you enable Check response code (integer) above. Enter a code that the target device must return. If it does not match, the sensor shows the Down status. Enter an integer value.

Check for Keywords (positive)

This setting is only visible if you enable Check response text above. Check if a certain keyword is part of the received value. If there is no match, the sensor shows the Down status.

• Disable: Do not check for positive keywords.
• Enable keyword check (positive): Check if a certain keyword exists in the received value. Define the keyword below.

Response Must Include

This setting is only visible if you Enable keyword check (positive) above. Define the search string that the returned value must contain. You can enter a simple string in plain text or a regular expression.

The search string must be case sensitive.

Search Method

Define the method with which you want to provide the search string:

• Simple string search: Search for a simple string in plain text.

The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character (as known from the Windows search). You cannot change this behavior. The literal search for these characters is only possible with a regular expression.

• Regular expression: Search with a regular expression (regex).

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

Check for Keywords (negative)

This setting is only visible if you enable Plain Text above. Check if a certain keyword is not part of the received value. If there is a match, the sensor shows the Down status.

• Disable: Do not check for negative keywords.
• Enable keyword check (negative): Check if a certain keyword does not exist in the received value. Define the keyword below.

Response Must Not Include

This setting is only visible if you Enable keyword check (negative) above. Define the search string that the returned value must not contain. You can enter a simple string in plain text or a regular expression.

The search string must be case sensitive.

Search Method

Define the method with which you want to provide the search string:

• Simple string search: Search for a simple string in plain text.

The characters * and ? work as placeholders. * stands for no number or any number of characters and ? stands for exactly one character (as known from the Windows search). You cannot change this behavior. The literal search for these characters is only possible with a regular expression.

• Regular expression: Search with a regex.

PRTG supports Perl Compatible Regular Expression (PCRE) regex. For more details, see section Regular Expressions.

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 names: Result of Sensor [ID].*): 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].* and Result of Sensor [ID].Data.*. This is for debugging purposes. PRTG overwrites these files with each scanning interval.

This option is not available when the sensor runs on the hosted probe of a PRTG hosted by Paessler instance.

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.

You can set a different primary channel later by clicking 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.
  You 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.

Scanning Interval

Select a scanning interval from the dropdown list. The scanning interval determines the amount of time that the sensor waits between two scans. Choose from:

• 30 seconds
• 60 seconds
• 5 minutes
• 10 minutes
• 15 minutes
• 30 minutes
• 1 hour
• 4 hours
• 6 hours
• 12 hours
• 1 day

You can change the available intervals in the system administration on PRTG on premises installations.

If a Sensor Query Fails

Select the number of scanning intervals that the sensor has time to reach and to check a device again if a sensor query fails. Depending on the option that you select, the sensor can try to reach and to check a device again several times before the sensor shows the 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 the Warning status. Choose from:

• Set sensor to down immediately: Set the sensor to the Down status immediately after the first request fails.
• Set sensor to warning for 1 interval, then set to down (recommended): Set the sensor to the Warning status after the first request fails. If the second request also fails, the sensor shows the Down status.
• Set sensor to warning for 2 intervals, then set to down: Set the sensor to the Down status only after the third request fails.
• Set sensor to warning for 3 intervals, then set to down: Set the sensor to the Down status only after the fourth request fails.
• Set sensor to warning for 4 intervals, then set to down: Set the sensor to the Down status only after the fifth request fails.
• Set sensor to warning for 5 intervals, then set to down: Set the sensor to the Down status only after the sixth request fails.

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

If you define error limits for a sensor's channels, the sensor immediately shows the Down status. None of the interval options apply.

If a channel uses lookup values, the sensor immediately shows the Down status. None of the interval options apply.

Schedule

Select a schedule from the list. You can use schedules to monitor during a certain time span (days or hours) every week. Choose from:

• None
• Saturdays
• Sundays
• Weekdays
• Weekdays Eight-To-Eight (08:00 - 20:00)
• Weekdays Nights (17:00 - 09:00)
• Weekdays Nights (20:00 - 08:00)
• Weekdays Nine-To-Five (09:00 - 17:00)
• Weekends

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

Maintenance Window

Select if you want to set up a one-time maintenance window. During a maintenance window, monitoring stops for the selected object and all child objects. They show the Paused status instead. Choose between:

• Not set (monitor continuously): Do not set up a one-time maintenance window. Monitoring is always active.
• Set up a one-time maintenance window: Set up a one-time maintenance window and pause monitoring. You can define a time span for a the pause below.

To 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 setting 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 one-time maintenance window.

Maintenance Ends

This setting 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 one-time maintenance window.

Dependency Type

Select 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 the Down status or in the Paused status because of 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 the 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.

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

Dependency Delay (Sec.)

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

After the master sensor for this dependency returns to the Up status, PRTG additionally delays the monitoring of the dependent objects by the time span you define. This can prevent false alarms, for example, after a server restart or to give systems more time for all services to start. Enter an integer value.

This 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.

User Group Access

Define the user groups that have access to the sensor. 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 sensor. The sensor neither shows up in lists nor in the device tree.
• Read access: Users in this group can see the sensor and view its monitoring results. They cannot edit any settings.
• Write access: Users in this group can see the sensor, view its monitoring results, and edit its settings. They cannot edit its access rights settings.
• Full access: Users in this group can see the sensor, view its monitoring results, edit its settings, and edit its access rights settings.

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