PRTG Manual: Syslog Receiver Sensor

The Syslog Receiver sensor receives and analyzes Syslog messages.

The sensor can show 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 on the syslog port
Syslog Receiver Sensor

Syslog Receiver Sensor

Sensor in Other Languages

  • Dutch: Syslog-ontvanger
  • French: Récepteur Syslog
  • German: Syslog-Empfänger
  • Japanese: Syslog レシーバー
  • Portuguese: Destinatário de syslog
  • Russian: Приемник Syslog
  • Simplified Chinese: 系统日志接收程序
  • Spanish: Receptor syslog

Remarks

  • 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.
  • This sensor only supports the User Datagram Protocol (UDP).
  • If you do not add the sensor to a probe device but to a different device in PRTG, be careful with the configuration: Ensure that the IP address or Domain Name System (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.
  • With the available filter options, you can individually define which types of messages the sensor considers for monitoring, and which messages it categorizes as warning or error messages. Depending on the filters, received messages are counted in the respective channels.
  • Add this sensor to the probe device to receive all messages of the remote probe system.
  • Add this sensor to a specific device to directly receive all messages from this device. This makes this sensor faster than when you use source filters.
  • This sensor supports the IPv6 protocol.
  • This sensor has a very high performance impact.

i_podYou cannot add this sensor to the hosted probe of a PRTG hosted by Paessler instance. If you want to use this sensor, add it to a remote probe device.

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.

Basic 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 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.

i_round_blueIt 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:

  • syslogsensor

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 (i_priority_1) to the highest priority (i_priority_5).

Syslog Specific

Setting

Description

Listen on Port

Enter the number of the port on which the sensor listens for Syslog messages. The default port is 514. 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. Select a period of time from the dropdown list.

Filter

i_square_cyanFor detailed information, see section Filter Rules.

Setting

Description

Include Filter

Define if you want to filter Syslog messages. If you leave this field empty or use the keyword any, the sensor processes all data. To only include specific types of messages, define filters using a special syntax.

Exclude Filter

Define which types of Syslog messages the sensor discards and does not process. To exclude specific types of messages, define filters using a special syntax.

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.

i_round_blueMessages are collected until a scanning interval ends. As long as the scanning interval is running, no status change happens. By default, the sensor changes to the Warning status after a scanning interval has finished and there has been at least one warning message (and no error message) during this interval. The sensor shows the Warning at least until the succeeding scanning interval has finished. If the sensor does not receive any warning or error message in this scanning interval, its status changes to the Up status again with the start of the next scanning interval.

Error Filter

Define which types of Syslog messages count for the Errors channel. To categorize received messages as error messages, define filters using a special syntax.

i_round_blueMessages are collected until a scanning interval ends. As long as the scanning interval is running, no status change happens. By default, the sensor changes to the Down status after a scanning interval has finished and there has been at least one error message during this interval. The sensor shows the Down status at least until the succeeding scanning interval has finished. If the sensor does not receive any warning or error message in this scanning interval, its status changes to the Up status again with the start of the next scanning interval.

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 b_channel_primary 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.
    i_round_redYou 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.

Inherited Settings

By default, all of the following settings are inherited from objects that are higher in the hierarchy. You should change them centrally in the root group settings if necessary. To change a setting for this object only, click b_inherited_enabled under the corresponding setting name to disable the inheritance. You then see the options described below.

i_square_cyanFor more information, see section Inheritance of Settings.

Scanning Interval

Click b_inherited_enabled to interrupt the inheritance.

Setting

Description

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

i_round_blueYou 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.

i_round_blueSensors 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.

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

i_round_blueIf a channel uses lookup values, the sensor immediately shows the Down status. None of the interval 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 schedules, dependencies, and maintenance windows. They are active at the same time as the parent objects' settings.

Setting

Description

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

i_square_cyanYou 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.

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 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.

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 setting is only visible if you enable Select a sensor above. Click b_search_light 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.

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.

Setting

Description

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.

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

Channel Unit Configuration

Click b_inherited_enabled to interrupt the inheritance.

Setting

Description

Channel Unit Types

For each type of channel, select the unit in which PRTG displays the data. If you define this setting 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

i_round_blueCustom channel types are only available on sensor level.

Debugging

Setting

Description

Log Data to Disk

Define if the probe writes a logfile of the received data for debugging purposes:

  • Off (recommended): Do not write additional logfiles. Recommended for normal use cases.
  • On: Write logfiles for all data received to the \Logs\debug subfolder of the PRTG data directory.
    i_round_redUse with caution. This option can create huge data files. 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 that you can combine with boolean operators (AND, OR, NOT) and brackets.

Field

Parameter

Example

source[ip]

Enter an IP address where the messages come from. IP masks and ranges are also possible.

  • source[10.0.23.50]
  • source[10.0.23.10-50]
  • source[10.0.23.10/24]
     

facility[number]

Enter any number or range from 0 to 23 specifying the program type that sends the message.

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

severity[number]

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

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

hostname[text]

Enter any string that specifies the hostname of a device in the message.

  • hostname[www.example.com]
     

tag[text]

Enter any string that specifies the tag of a program or process in the message.

  • tag[su]
     

appname[text]

Enter any string that specifies the appname part of the message.

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

procid[text]

Enter any string that specifies the process identifier part of the message.

  • procid[1860]
     

msgid[text]

Enter any string that specifies the message identifier part of the message.

  • msgid[ID47]
     

message[parttext]

Enter any string that specifies the message part of the message. (Any substring matches. This value is case insensitive.)

  • message[Error]
     

data[id,param,value]

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

data[parttext]

This checks if the specified substring matches structured data as displayed in the corresponding table.

data[id,param]

This checks if the parameter exists in the specified ID element.

i_round_redString parameters (except the substring in message) have to exactly match 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 \Syslog Database subfolder of the PRTG data directory. To review and analyze all received messages, you can directly access the most recent data in a table list on the PRTG web interface. You can access this list via the sensor's Overview tab.

i_round_blueReceived Syslog messages are only shown in the table on the Overview tab after an (automatic) page refresh following a sensor scan. The default value for auto refresh is 30 seconds.

For more details and further filter options, click the Messages tab of the Syslog Receiver sensor. You 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 those available in the sensor settings, but you can define them without using formulas. Provide the desired parameters and PRTG automatically loads the filtered list.

i_round_blueYou can automatically add a filter by clicking the content of a column.

Advanced Filter Settings

You can open advanced filter settings by clicking b_filter_advanced in the Filter row. The Advanced Filter appears in a popup window. In the text field, you can define a filter using the syntax as specified in section Filter Rules for Syslog Messages.

If you provided filter parameters on the Messages tab, the advanced filter already includes 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

i_square_blueKNOWLEDGE BASE

How can I configure sensors using speed limits to keep the status for more than one interval?

What placeholders can I use with PRTG?

 

i_playVIDEO TUTORIAL

Trap Receiver and Syslog Receiver

Sensor Settings Overview

For more information about sensor settings, see the following sections: