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Aurelio, System Admin at Paessler AG

The Syslog Receiver sensor receives and analyzes syslog messages.

It shows the following:

  • Number of received syslog messages per second
  • Number of messages categorized as "warning" per second
  • Number of messages categorized as "error" per second
  • Number of dropped packets per second
Syslog Receiver SensorSyslog Receiver Sensor

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

Remarks

  • With the available filter options, you can define individually which types of messages the sensor will consider for monitoring, and which messages it will categorize as warning or error messages. Depending on the filters, received messages are counted in the respective channels.
  • Add the sensor to the probe device to receive all messages of the system running the probe.
  • Add the sensor to a specific device to receive all messages from this device directly. This makes this sensor type faster than just using source filters.
  • You can use specific placeholders in email notification templates to see the messages when you receive an email notification. See the Knowledge Base: What placeholders can I use with PRTG?
  • Note: Sensor states of this sensor type persist for one scanning interval only. If there is no warning or error message in the following scanning interval, the sensor will show an up status again.
  • Note: If you do not add the sensor to a probe device but to another device in PRTG, be careful with the configuration: Ensure that the IP address or DNS name of the parent device matches the proper sender. For example, if you want to receive messages from a Storage Area Network (SAN), you might have to add a device to PRTG using the IP address of a specific array member that sends the messages. Providing a DNS name that points to the IP address of a whole group might not work for SANs.
  • Note: This sensor type cannot be used in cluster mode. You can set it up on a local probe or remote probe only, not on a cluster probe.
  • For a general introduction to the receiver's configuration, please see manual section Monitoring Syslogs and SNMP Traps.
  • Note: This sensor type can have a high impact on the performance of your monitoring system. Please use it with care! We recommend that you use not more than 50 sensors of this sensor type on each probe.

Add Sensor

The Add Sensor dialog appears when adding a new sensor to a device manually. 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 on the Settings tab to change its settings.

Note: Usually, a sensor connects to the IP Address or DNS Name of the parent device on which 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 space or comma. 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 it, 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).

Syslog Specific

Listen on Port

Enter the number of the port on which the sensor waits for Syslog messages. The default port is 514. Please enter an integer value. We recommend that you use the default value.

Purge Messages After

Define how long PRTG stores received Syslog messages for analysis. Choose a period of time from the drop down list.

Filter

Include Filter

Define if you want to filter Syslog messages. If you leave this field empty or use the keyword "any ", the sensor will process all data. To include specific types of messages only, define filters using a special syntax. For more information, see section Filter Rules .

Exclude Filter

Define which types of Syslog messages the sensor will discard and not process. To exclude specific types of messages, define filters using a special syntax. For more information, see section Filter Rules .

Warning Filter

Define which types of Syslog messages count for the Warnings channel. To categorize received messages as warning messages, define filters using a special syntax. For more information, see section Filter Rules .

Note: Messages are collected until a scanning interval ends. as long as the scanning interval is running, no status change will happen. By default, the sensor will turn into a Warning status after a scanning interval has finished and there was at least one warning message (and no error message) during this interval. The status will remain Warning at least until the succeeding scanning interval has finished. If in this scanning interval no warning or error message occurred, the status of the sensor will turn Up again after the interval.

Error Filter

Define which types of syslog messages will count for the Errors channel. To categorize received messages as error messages, define filters using a special syntax. For more information, see section Filter Rules .

Note: Messages are collected until a scanning interval ends. As long as the scanning interval is running, no status change will happen. By default, the sensor will turn into a Down status after a scanning interval has finished and there was at least one error message during this interval. The status will remain Down at least until the succeeding scanning interval has finished. If the sensor did not receive any warning or error message in this scanning interval, the status of the sensor will turn Up again after the interval.

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. Note: You can set another primary channel later by clicking on 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 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 only for this object, disable inheritance by clicking on the check mark before the corresponding setting name. You will then see the options described below.

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.

When a Sensor Reports an Error

Define the number of scanning intervals that a sensor has time to report an error before the sensor will be set to a Down status. The sensor can try to reach a device several times, depending on the 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 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.

Note: Sensors 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 "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.

Note: If a channel uses lookup values, the sensor will always be set to a Down status immediately, so no "wait" options will apply.

Schedules, Dependencies, and Maintenance Window

Note: Inheritance 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.

Note: Schedules 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.

Note: To 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.

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-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.

Note: This 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.

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

Channel Unit Configuration

Channel Unit Types

For each type of sensor channel, define the unit in which data is displayed. If defined on probe, group, or device level, these settings can be inherited to all sensors underneath. You can set units for the following channel types (if available):

  • Bandwidth
  • Memory
  • Disk
  • File
  • Custom

Note: Custom channel types can be set on sensor level only.

Debugging

Log Data to Disk

Define if the probe will write a log file of the received data to the data folder (see Data Storage ) to the disk for debugging purposes. Choose between:

  • Off (recommended) : Do not write additional log files. Recommended for normal use cases.
  • On : Write log files for all data received.

Note: Use with caution! When enabled, huge data files can be created. Please use for a short time and for debugging purposes only.

Filter Rules for Syslog Messages

Filter rules are used for the include, exclude, warning, and error definition fields of the Syslog Receiver sensor. They are based on the following format:

field[filter]

 
You can use various filters suitable to your needs. Include and exclude filters define which messages to monitor. Warning and error filters define how to categorize received messages. Provide these filters in the sensor settings as formulas. Formulas are fields which you can combine with boolean operators (AND , OR , NOT ) and brackets.

Field

Parameter

Example

source [ip ]

the IP address where the messages will be received from; masks and ranges are also possible

  • source[10.0.23.50]
  • source[10.0.23.10-50]
  • source[10.0.23.10/255]
     

facility [number ]

any number or range from 0 to 23 specifying the type of program sending the message

  • facility[2]
  • facility[5-7]
  • facility[5] OR facility[6]
     

severity [number ]

any number or range from 0 (emergency) to 7 (debug) specifying the type of message

  • severity[4]
  • severity[1-3]
  • severity[1] AND severity[2]
     

hostname [text ]

any string specifying the hostname of a device in the message

  • hostname[www.example.com]
     

tag [text ]

any string specifying the tag of a program or process in the message

  • tag[su]
     

appname [text ]

any string specifying the appname part of the message

  • appname[myproc]
  • appname[demo] AND msgid[m42]
     

procid [text ]

any string specifying the process identifier part of the message

  • procid[1860]
     

msgid [text ]

any string specifying the message identifier part of the message

  • msgid[ID47]
     

message [parttext ]

any string specifying the message part of the message (substring will match; case insensitive !)

  • message[Error]
     

data [id ,param ,value ]

checks the SD-ID block of the message's structured data for a parameter matching the given value

  • data[exampleSDID@12345,eventSource,Application]
     

data [parttext ]

checks if the given substring matches on structured data as displayed in the corresponding table

  • data[exampleSDID@1234]
     

data [id ,param ]

checks if the parameter exists in the given ID element

  • data[exampleSDID@1234,eventSource]
     

Note: String parameters (except the substring in message ) have to match exactly the particular parts of the message. They are case sensitive!

Messages Tab: Review and Analyze Syslog Messages

PRTG stores received Syslog messages as common files in the data folder (see section Data Storage ). To review and analyze all received messages, you can access the most recent data directly in a table list in the PRTG web interface. You can access this list via the Overview tab of the sensors.

Note: Received syslogs are only shown after an (automatic) page refresh following to a sensor scan in the table on the Overview tab (default for auto refresh is 30 seconds).

For more details and further filter options, click the Messages tab of the Syslog Receiver sensor. You will see all received messages in a table list. On the top, you have display filter options to drill down into the data for specific events of your interest. The filters are the same as available in the sensor settings, but you can define them without using formulas. Provide the desired parameters and PRTG loads the filtered list automatically.

Note: You can automatically add a filter by clicking the content of a column.

 
Advanced Filter Settings

You can open advanced filter settings by clicking the gear icon in the Filter row. The Advanced Filter will appear in a popup window. In the text field, you can define a filter using the syntax as given in section Filter Rules for Syslog Messages . If you have provided filter parameters on the Messages tab, the advanced filter will already include them as a corresponding formula with the correct syntax. You can adjust this filter to your needs. You can also copy the automatically created and manually adjusted formula for usage in the filter fields of the sensor settings.

More

Blog Article: Introducing the New High Performance Syslog and SNMP Trap Receiver Sensors

Knowledge Base: What placeholders can I use with PRTG?

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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