PRTG Manual: Syslog Receiver Sensor
The Syslog Receiver sensor receives and analyzes Syslog messages.
Syslog Receiver Sensor
For a detailed list and descriptions of the channels that this sensor can show, see section Channel List.
- Dutch: Syslog ontvanger
- French: Récepteur Syslog
- German: Syslog-Empfänger
- Japanese: Syslog レシーバー
- Portuguese: Receptor de Syslog
- Russian: Приемник Syslog
- Simplified Chinese: 系统日志接收程序
- Spanish: Receptor de Syslog
- This sensor has a very high performance impact. 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 need 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.
- You cannot use this sensor in cluster mode. You can only set it up on a local probe or a remote probe but not on a cluster probe.
- For a general introduction to the receiver's configuration, see section Monitoring Syslogs and SNMP Traps.
- You can use specific placeholders in email notification templates to see the messages when you receive an email notification. See section List of Placeholders for Notifications.
- The sensor states of this sensor persist for one scanning interval only. After showing a Warning status or a Down status, and if there is no warning or error message in the following scanning interval, the sensor shows an Up status again. For a workaround, see the Knowledge Base: How can I configure sensors using speed limits to keep the status for more than one interval?
You cannot add this sensor to the hosted probe of a PRTG Hosted Monitor instance. If you want to use this sensor, add it to a remote probe device.
The Add Sensor dialog appears when you manually add a new sensor to a device. It only shows the settings that are required to create the sensor. You can change nearly all settings on the sensor's Settings tab after creation.
Click the Settings tab of a sensor to change its settings.
Basic Sensor Settings
Setting |
Description |
|---|---|
Sensor Name |
Enter a name to identify the sensor. |
Parent Tags |
Shows tags that the sensor inherits from its parent device, parent group, and parent probe.
|
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.
The sensor has the following default tags that are automatically predefined in the sensor's settings when you add the sensor:
|
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 ( |
Usually, a sensor connects to the IP Address/DNS Name of the parent device. See the device settings for details. For some sensors, you can explicitly define the monitoring target in the sensor settings.
Syslog Specific
Setting |
Description |
|---|---|
Port |
Enter the number of the port on which the sensor listens for Syslog messages. The default port is 514. Enter an integer.
|
Purge Messages After |
Define how long PRTG stores received Syslog messages for analysis. Select a period of time from the dropdown list. |
For detailed information, see section Filter Rules.
Filter
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.
|
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.
|
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.
|
Graph Type |
Define how different channels are shown for this sensor:
|
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. |
By default, all of these settings are inherited from objects that are higher in the hierarchy. We recommend that you change them centrally in the root group settings if necessary. To change a setting for this object only, click 
under the corresponding setting name to disable the inheritance and to display its options.
For more information, see section Inheritance of Settings.
Scanning Interval
For more information, see section Root Group Settings, section Scanning Interval.
Schedules, Dependencies, and Maintenance Window
You 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.
Schedules, Dependencies, and Maintenance Window
For more information, see section Root Group Settings, section Schedules, Dependencies, and Maintenance Window.
Access Rights
For more information, see section Root Group Settings, section Access Rights.
Which channel units are available depends on the sensor type and the available parameters. If no configurable channels are available, this field shows No configurable channels.
Channel Unit Configuration
For more information, see section Root Group Settings, section Channel Unit Configuration.
Debug Options
Debug Options
Setting |
Description |
|---|---|
Result Handling |
Define what PRTG does with the sensor result:
|
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. |
|
facility[number] |
Enter any number or range from 0 to 23 specifying the program type that sends the message. |
|
severity[number] |
Enter any number or range from 0 (emergency) to 7 (debug) specifying the message type. |
|
hostname[text] |
Enter any string that specifies the hostname of a device in the message. |
|
tag[text] |
Enter any string that specifies the tag of a program or process in the message. |
|
appname[text] |
Enter any string that specifies the appname part of the message. |
|
procid[text] |
Enter any string that specifies the process identifier part of the message. |
|
msgid[text] |
Enter any string that specifies the message identifier part of the message. |
|
message[parttext] |
Enter any string that specifies the message part of the message. (Any substring matches. This value is case insensitive.) |
|
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. |
|
String parameters (except the substring in message) must 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.
Received 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.
You can automatically add a filter by clicking the content of a column.
Advanced Filter Settings
You can open advanced filter settings by clicking 
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.
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.
Which channels the sensor actually shows might depend on the target device, the available components, and the sensor setup.
Channel |
Description |
|---|---|
Downtime |
In the channel table on the Overview tab, this channel never shows any values. PRTG uses this channel in graphs and reports to show the amount of time in which the sensor was in the Down status in percent. |
Drops |
The number of dropped packets per second on the syslog port |
Errors |
The number of messages categorized as "error" per second |
Messages |
The number of received Syslog messages per second
|
Warnings |
The number of messages categorized as "warning" per second |
Knowledge Base
How can I configure sensors using speed limits to keep the status for more than one interval?
What security features does PRTG include?
VIDEO TUTORIAL
SNMP Trap receiver and syslog receiver sensors
