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syslog-ng Premium Edition 7.0.20 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng The syslog-ng PE quick-start guide The syslog-ng PE configuration file Collecting log messages — sources and source drivers
How sources work default-network-drivers: Receive and parse common syslog messages internal: Collecting internal messages file: Collecting messages from text files wildcard-file: Collecting messages from multiple text files linux-audit: Collecting messages from Linux audit logs network: Collecting messages using the RFC3164 protocol (network() driver) office365: Fetching logs from Office 365 osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources snmptrap: Read Net-SNMP traps syslog: Collecting messages using the IETF syslog protocol (syslog() driver) system: Collecting the system-specific log messages of a platform systemd-journal: Collecting messages from the systemd-journal system log storage systemd-syslog: Collecting systemd messages using a socket tcp, tcp6, udp, udp6: Collecting messages from remote hosts using the BSD syslog protocol udp-balancer: Receiving UDP messages at very high rate unix-stream, unix-dgram: Collecting messages from UNIX domain sockets windowsevent: Collecting Windows event logs
Sending and storing log messages — destinations and destination drivers
elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Event Collector file: Storing messages in plain-text files hdfs: Storing messages on the Hadoop Distributed File System (HDFS) http: Posting messages over HTTP kafka: Publishing messages to Apache Kafka logstore: Storing messages in encrypted files mongodb: Storing messages in a MongoDB database network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) pipe: Sending messages to named pipes program: Sending messages to external applications python: writing custom Python destinations sentinel: Sending logs to the Microsoft Azure Sentinel cloud snmp: Sending SNMP traps smtp: Generating SMTP messages (email) from logs splunk-hec: Sending messages to Splunk HTTP Event Collector sql: Storing messages in an SQL database stackdriver: Sending logs to the Google Stackdriver cloud syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng(): Forward logs to another syslog-ng node tcp, tcp6, udp, udp6: Sending messages to a remote log server using the legacy BSD-syslog protocol (tcp(), udp() drivers) unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal — usertty() destination Client-side failover
Routing messages: log paths, flags, and filters Global options of syslog-ng PE TLS-encrypted message transfer Advanced Log Transfer Protocol Reliability and minimizing the loss of log messages Manipulating messages parser: Parse and segment structured messages Processing message content with a pattern database Correlating log messages Enriching log messages with external data Monitoring statistics and metrics of syslog-ng Multithreading and scaling in syslog-ng PE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Glossary

python() destination options

The Python destination allows you to write your own destination in Python. The python() destination has the following options. The class() option is mandatory. For details on writing destinations in Python, see python: writing custom Python destinations.

class()
Type: string
Default: N/A

Description: The name of the Python class that implements the destination, for example:

python(
    class("MyPythonDestination")
);

If you want to store the Python code in an external Python file, the class() option must include the name of the Python file containing the class, without the path and the .py extension, for example:

python(
    class("MyPythonfilename.MyPythonDestination")
);

For details, see Python code in external files

disk-buffer()

Description: This option enables putting outgoing messages into the disk-buffer file of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:

reliable()
Type: yes|no
Default: no

Description: If set to yes, syslog-ng PE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng PE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer option will be used. This provides a faster, but less reliable disk-buffer option.

Caution:

Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer file, the messages stored in the disk-buffer file will be lost.

dir()
Type: string
Default: N/A

Description: Defines the folder where the disk-buffer files are stored.

Note that changing the value the dir() option will not move or copy existing files from the old directory to the new one.

Caution:

When creating a new dir() option for a disk-buffer file, or modifying an existing one, make sure you delete the persist file.

syslog-ng PE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file is not deleted after modifying the dir() option, then following a restart, syslog-ng PE will look for or create disk-buffer files in their old location. To ensure that syslog-ng PE uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to.

disk-buf-size()
Type: number [bytes]
Default:

Description: This is a required option. The maximum size of the disk-buffer file in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option.
mem-buf-length()
Type: number [messages]
Default: 10000
Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes.
mem-buf-size()
Type: number [bytes]
Default: 163840000
Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk-buffer file. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no.
qout-size()
Type: number [messages]
Default: 64
Description: The number of messages stored in the output buffer of the destination. Note that if you change the value of this option and the disk-buffer file already exists, the change will take effect when the disk-buffer file becomes empty.

Options reliable() and disk-buf-size() are required options.

Example: Examples for using disk-buffer()

In the following case reliable disk-buffer() is used.

destination d_demo {
    network("127.0.0.1"
        port(3333)
        disk-buffer(
            mem-buf-size(10000)
            disk-buf-size(2000000)
            reliable(yes)
            dir("/tmp/disk-buffer")
        )
    );
};

In the following case normal disk-buffer() is used.

destination d_demo {
    network("127.0.0.1"
        port(3333)
        disk-buffer(
            mem-buf-length(10000)
            disk-buf-size(2000000)
            reliable(no)
            dir("/tmp/disk-buffer")
        )
    );
};
frac-digits()
Type: number
Default: 0

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

log-fifo-size()
Type: number
Default: Use global setting.

Description: The number of messages that the output queue can store.

on-error()
Accepted values:

drop-message|drop-property|fallback-to-string|

silently-drop-message|silently-drop-property|silently-fallback-to-string

Default: Use the global setting (which defaults to drop-message)

Description: Controls what happens when type-casting fails and syslog-ng PE cannot convert some data to the specified type. By default, syslog-ng PE drops the entire message and logs the error. Currently the value-pairs() option uses the settings of on-error().

  • drop-message: Drop the entire message and log an error message to the internal() source. This is the default behavior of syslog-ng PE.

  • drop-property: Omit the affected property (macro, template, or message-field) from the log message and log an error message to the internal() source.

  • fallback-to-string: Convert the property to string and log an error message to the internal() source.

  • silently-drop-message: Drop the entire message silently, without logging the error.

  • silently-drop-property: Omit the affected property (macro, template, or message-field) silently, without logging the error.

  • silently-fallback-to-string: Convert the property to string silently, without logging the error.

options()
Type: string
Default: N/A

Description: This option allows you to pass custom values from the configuration file to the Python code. Enclose both the option names and their values in double-quotes. The Python code will receive these values during initialization as the options dictionary. For example, you can use this to set the IP address of the server from the configuration file, so it is not hard-coded in the Python object.

python(
    class("MyPythonClass")
    options(
        "host" "127.0.0.1"
        "port" "1883"
        "otheroption" "value")
);

For example, you can refer to the value of the host field in the Python code as options["host"]. Note that the Python code receives the values as strings, so you might have to cast them to the type required, for example: int(options["port"])

persist-name()
Type: string
Default:

None

Description:If you receive the following error message during syslog-ng PE startup, set the persist-name() option of the duplicate drivers:

Error checking the uniqueness of the persist names, please override it with persist-name option. Shutting down.

This error occurs if you use identical drivers in multiple sources, for example, if you configure two file sources to read from the same file. In this case, set the persist-name() of the drivers to a custom string, for example, persist-name("example-persist-name1").

NOTE:

Starting with 7.0.19, syslog-ng PE assigns a persist name to Python sources and destinations. The persist name is generated from the class name. If you want to use the same Python class multiple times in your syslog-ng PE configuration, add a unique persist-name() to each source or destination, otherwise syslog-ng PE will not start. For example:

log {
    source { python(class(PyNetworkSource) options("port" "8080") persist-name("<unique-string>); };
    source { python(class(PyNetworkSource) options("port" "8081")); };
  };

Alternatively, you can include the following line in the Python package: @staticmethod generate_persist_name. For example:

from syslogng import LogSource
  class PyNetworSource(LogSource):
    @staticmethod
    def generate_persist_name(options):
        return options["port"]
    def run(self):
        pass
    def request_exit(self):
        pass
throttle()
Type: number
Default: 0

Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using the disk-buffer option as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.

value-pairs()
Type: parameter list of the value-pairs() option
Default:
scope("selected-macros" "nv-pairs")

Description: The value-pairs() option creates structured name-value pairs from the data and metadata of the log message. For details on using value-pairs(), see Structuring macros, metadata, and other value-pairs.

NOTE:

Empty keys are not logged.

You can use this option to limit which name-value pairs are passed to the Python code for each message. Note that if you use the value-pairs() option, the Python code receives the specified value-pairs as a Python dict. Otherwise, it receives the message object. In the following example, only the text of the log message is passed to Python.

destination d_python_to_file {
    python(
        class("pythonexample.TextDestination")
        value-pairs(key(MESSAGE))
    );
};

sentinel: Sending logs to the Microsoft Azure Sentinel cloud

Microsoft Azure Sentinel is Microsoft's native cloud based SIEM solution. Beside Microsoft's own cloud services, it can accept log messages from external sources. Microsoft provides 26 predefined Data connectors and a HTTP Data Collector API for further integrations. Using this public HTTP REST interface, syslog-ng Premium Edition (syslog-ng PE) can ingest log messages directly to Microsoft Azure Sentinel cloud using the http() destination driver.

For more information about Microsoft Azure Sentinel, see Microsoft Azure: Azure Sentinel documentation.

For more information about Data connectors used in Microsoft Azure Sentinel, see Microsoft Azure: Connect data sources.

Caution:

This is an EXPERIMENTAL feature still under development and with no backward compatibility. Its full impact on production systems has not been determined yet, and potential future changes in functionality and the user interface may result in compatibility issues in your current settings. Therefore, any potential future issues resulting from incompatibility are not covered by support.

One Identity recommends the following:

  • Consider the potential risks when using this functionality in a production environment.
  • Closely and regularly keep track of official One Identity announcements about potential changes in functionality and the user interface. If these potential changes affect your configuration, check the changes you have to make in your configuration, otherwise your syslog-ng PE may not start after upgrade.
  • Always perform tests prior to upgrades in order to avoid the risks mentioned.

However, you are welcome to try this feature and if you have any feedback, Contact One Identity.

Caution:

Hazard of data loss!

The sentinel() destination's fields() parameter is optional and has the following default values:

fields("Computer=$HOST HostName=$HOST ProcessID=$PID SyslogMessage=$MSGHDR$MSG Facility=$FACILITY SeverityLevel=$LEVEL HostIP=$SOURCEIP EventTime=$S_ISODATE")

Although it is possible to customize these default values, an incorrect configuration may result in log loss. The sentinel() destination is an EXPERIMENTAL feature, and data loss resulting from customized default values is not yet covered by support. Therefore, One Identity recommends that you do not customize the default values of the fields() parameter unless you know exactly what you are doing.

Limitations

The current implementation of the sentinel() destination has the following limitations:

  • Only the PUT and the POST methods are supported.

  • HTTPS connections, as well as password-based and certificate-based authentication, are supported.

  • If the server returns a status code beginning with 4 (for example, 404) to the POST or PUT request, syslog-ng PE drops the message without attempting to resend it.

NOTE: Typically, only the central syslog-ng PE server uses this destination. For more information on the server mode, see Server mode.

Declaration
destination d_sentinel {
    sentinel(
        workspace-id("<MS provided Workspace ID / UUID>")
        auth-secret("<MS provided Shared key / Secret>")
    );
}

Configuring the sentinel() destination to send logs to the Microsoft Azure Sentinel cloud

Starting with version 7.0.19, syslog-ng Premium Edition (syslog-ng PE) can ingest log messages directly to Microsoft Azure Sentinel by using Microsoft Azure Sentinel's public HTTP Data Collector API interface.

The syslog-ng PE application can directly post log messages to the Microsoft Azure Sentinel cloud using the http() destination driver.

Prerequisites

To configure syslog-ng PE to forward messages to Microsoft Azure Sentinel, you must have an active Microsoft Azure Sentinel Workspace. For more information, see Microsoft Azure Sentinel: Quickstart: On-board Azure Sentinel.

Getting the required credentials to configure syslog-ng PE as a Data Connector for Microsoft Azure Sentinel

While configuring your Microsoft Azure Sentinel Workspace according to the Microsoft Azure Sentinel: Quickstart: On-board Azure Sentinel guide's Connect data sources section, you will find certain credentials of the selected Microsoft Azure Sentinel Workspace (namely, WORKSPACE ID and PRIMARY KEY) that you should make a note of. The WORKSPACE ID and PRIMARY KEY credentials are required so that syslog-ng PE can authenticate to Microsoft servers.

To gather the required credentials to configure syslog-ng PE as a Data connector for Microsoft Azure Sentinel,

  1. Log in to your Microsoft Azure Sentinel account, then navigate to Dashboard > Azure Sentinel workspaces.
  2. Select the workspace you want to use, then under the selected workspace, select Data Connectors.
  3. Select Syslog from the list of connectors.

    A new panel will open on the right.

  4. Select Open connector page from the new panel on the right.
  5. Navigate back to Dashboard > Azure Sentinel workspaces > Azure Sentinel - Data connectors > Syslog.
  6. Under Instructions, select Open your workspace advanced settings configuration.
  7. Navigate to Dashboard > Azure Sentinel - Data connectors > Syslog > Advanced settings.
  8. Copy the following information from Connected Sources > Linux Servers:
    • WORKSPACE ID

      In the syslog-ng PE configuration, this will function as the workspace-id parameter.

    • PRIMARY KEY

      In the syslog-ng PE configuration, this will function as the auth-secret parameter.

Example: Using Azure Sentinel credentials in the sentinel() destination

In your syslog-ng PE configuration, you can use the credentials you have gathered like this:

d_sentinel {
    sentinel(
        workspace-id("01234567-89ab-cdef-0123-456789abcdef") // Provided by Microsoft: unique hexadecimal number, identifying your Sentinel instance.
        auth-secret("MDEyMzQ1Njc4OWFiY2RlZjAxMjM0NTY3ODlhYmNkZWYwMTIzNDU2Nzg5YWJjZGVmMDEyMzQ1Njc4OWFiY2RlZgo=") // Provided by Microsoft: Base64-encoded secret, identifying your application.
 
        # optional
        log-type("Syslog_CL")
    );
};

Caution:

Hazard of data loss!

The sentinel() destination's fields() parameter is optional and has the following default values:

fields("Computer=$HOST HostName=$HOST ProcessID=$PID SyslogMessage=$MSGHDR$MSG Facility=$FACILITY SeverityLevel=$LEVEL HostIP=$SOURCEIP EventTime=$S_ISODATE")

Although it is possible to customize these default values, an incorrect configuration may result in log loss. The sentinel() destination is an EXPERIMENTAL feature, and data loss resulting from customized default values is not yet covered by support. Therefore, One Identity recommends that you do not customize the default values of the fields() parameter unless you know exactly what you are doing.

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