<%NUMBERING1%>.<%NUMBERING2%>.<%NUMBERING3%> PRTG Manual: Syslog Receiver Sensor

The Syslog Receiver sensor receives and analyzes syslog messages. It shows the overall number of received syslog messages per second, warning and error messages per second, as well as the number of dropped packets per second.

With the available filter options, you can define individually which types of messages will be considered for monitoring and thus stored, and which messages will be recognized as warning or error messages. Depending on the filters, received messages will be counted in the respective channels. The messages are stored in an internal database for later analysis. The received data will be available on your respective probe system as common files, as well as via the web interface.

You can add the sensor to the probe device on the one hand; then the sensor will receive all messages of the system running the probe. Alternatively, you can add the sensor to a specific device to gain all messages from this device directly; this will make this sensor type faster than just using source filters.

You can use syslog specific placeholders in email notification templates to see the messages when you receive an email notification. See the More section below for more information about placeholders.

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 syslog sender. For example, if you want to receive syslogs 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 syslog receiver's configuration, please see section Monitoring Syslogs and SNMP Traps.

Important notice: Currently, this sensor type is in beta status. The methods of operating can change at any time, as well as the available settings. Do not expect that all functions will work properly, or that this sensor works as expected at all. Be aware that this type of sensor can be removed again from PRTG at any time.

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).

Syslog Specific

Listen on Port

Enter the port the sensor will listen on for Syslog messages. Usually port 514 is used. Please enter an integer value. We recommend using the default value.

Purge Messages After

Define how long received syslog messages will be stored 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", all data will be processed. 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 will be discarded and not processed. 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 will 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 in this scanning interval no warning or error message occurred, 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 underneath 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.

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.

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.

When a Sensor Reports an Error

With this setting, you can define the number of scanning intervals a sensor has to report an error until the sensor will be set to a Down status. The sensor can try reaching a device several times, depending on your 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 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": The sensor will only show an error status after three failed requests in a row.
  • Set sensor to "warning" for 3 intervals, then set to "down": The sensor will only show an error status after four failed requests in a row.
  • Set sensor to "warning" for 4 intervals, then set to "down": The sensor will only show an error status after five failed requests in a row.
  • Set sensor to "warning" for 5 intervals, then set to "down": The sensor will only show an error status after six failed requests in a row.

Note: Sensors that monitor via Windows Management Instrumentation (WMI) will always wait at least one scanning interval until an error is shown. 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.

Schedules, Dependencies, and Maintenance Window

Note: Inheritance for schedules, dependencies, and maintenance windows cannot be interrupted; the according settings from the parent objects will always be active. However, you can define additional settings here. They will be active in parallel to the parent objects' settings.

Schedule

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

Maintenance Window

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

  • Not set (monitor continuously): No maintenance window will be set.
  • Set up a one-time maintenance window: Pause monitoring within a maintenance window.

Maintenance Begins At

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

Maintenance End At

This field is only visible if maintenance window is enabled 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 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. 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-glass symbol and use the object selector to choose an object on which the current sensor will be dependent on.

Delay (Seconds)

Define a time span. After the master object for this dependency comes back to an Up status, monitoring of the depending objects will be additionally delayed by the defined time span. This can help 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 in seconds. Note: This setting is not available if you choose this sensor to be the Master object for parent. In this case, please define delays in the parent Device Settings or 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 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.

For more details about access rights, please see 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 will be monitored; warning and error filters define how received messages will be categorized. Provide these filters in the sensor settings as formulas. Formulas are fields which can be combined 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

Received syslog messages are stored as common files in PRTG's data folder (see section Data Storage). In order to review and analyze all received messages, you can access the most recent data directly in PRTG's web interface via the Overview tab of the respective sensor in a table list. 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 on 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 will load the filtered list automatically. Note: You can automatically add a filter by clicking on the content of a column.

 
Advanced Filter Settings

You can open advanced filter settings with a click on 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, these will be already included in the advanced filter 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

In order to change display settings, spike filter, and limits, please switch to the sensor's Overview tab and click on the gear icon of a specific channel. 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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