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syslog-ng Premium Edition 7.0.34 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng PE 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 google-pubsub: collecting messages from the Google Pub/Sub messaging service wildcard-file: Collecting messages from multiple text files linux-audit: Collecting messages from Linux audit logs mssql, oracle, sql: collecting messages from an SQL database 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 google_bigquery(): Sending logs to a Google BigQuery table google_bigquery_managedaccount(): Sending logs to a Google BigQuery table authenticated by Google Cloud managed service account google_pubsub(): Sending logs to the Google Cloud Pub/Sub messaging service google_pubsub-managedaccount(): Sending logs to the Google Cloud Pub/Sub messaging service authenticated by Google Cloud managed service account hdfs: Storing messages on the Hadoop Distributed File System (HDFS) http: Posting messages over HTTP kafka(): Publishing messages to Apache Kafka (Java implementation) (DEPRECATED) kafka-c(): Publishing messages to Apache Kafka using the librdkafka client (C implementation) 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 Transport 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() and python-fetcher() source options

The python() and python-fetcher() drivers have the following options.

class()
Type: string
Default: N/A

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

python(
    class("MyPythonSource")
);

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.MyPythonSource")
);

For details, see Python code in external files

flags()
Type: assume-utf8, empty-lines, expect-hostname, guess-timezone, kernel, no-hostname, no-multi-line, no-parse, sanitize-utf8, store-legacy-msghdr, store-raw-message, syslog-protocol, validate-utf8
Default: empty set

Description: Specifies the log parsing options of the source.

  • assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.

  • empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, syslog-ng PE removes empty lines automatically.

  • expect-hostname: If the expect-hostname flag is enabled, syslog-ng PE will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.

  • kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.

  • no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way syslog-ng PE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:

    source s_dell {
        network(
            port(2000)
            flags(no-hostname)
        );
    };
  • no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.

  • no-parse: By default, syslog-ng PE parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The syslog-ng PE application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.

    If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, syslog-ng PE generates a new syslog header (timestamp, host, and so on) automatically. Note that since flags(no-parse) disables message parsing, it interferes with other flags, for example, disables flags(no-multi-line).

  • dont-store-legacy-msghdr: By default, syslog-ng stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (syslog-ng automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.

  • sanitize-utf8: When using the sanitize-utf8 flag, syslog-ng PE converts non-UTF-8 input to an escaped form, which is valid UTF-8.

  • store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another syslog-ng node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 7.0.9 and later.

  • syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.

  • validate-utf8: The validate-utf8 flag enables encoding-verification for messages formatted according to the new IETF syslog standard (for details, see IETF-syslog messages). If theBOM1character is missing, but the message is otherwise UTF-8 compliant, syslog-ng automatically adds the BOM character to the message.

The flags and the hostname-related options (for example, use-dns) set in the configuration file influence the behavior of the LogMessage.parse() method of the Python source. They have no effect if you set the message or the hostname directly, without using LogMessage.parse().

keep-hostname()
Type: yes or no
Default: no

Description: Enable or disable hostname rewriting.

  • If enabled (keep-hostname(yes)), syslog-ng PE assumes that the incoming log message was sent by the host specified in the HOST field of the message.

  • If disabled (keep-hostname(no)), syslog-ng PE rewrites the HOST field of the message, either to the IP address (if the use-dns() parameter is set to no), or to the hostname (if the use-dns() parameter is set to yes and the IP address can be resolved to a hostname) of the host sending the message to syslog-ng PE. For details on using name resolution in syslog-ng PE, see Using name resolution in syslog-ng.

NOTE: If the log message does not contain a hostname in its HOST field, syslog-ng PE automatically adds a hostname to the message.

  • For messages received from the network, this hostname is the address of the host that sent the message (this means the address of the last hop if the message was transferred via a relay).

  • For messages received from the local host, syslog-ng PE adds the name of the host.

This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

NOTE: When relaying messages, enable this option on the syslog-ng PE server and also on every relay, otherwise syslog-ng PE will treat incoming messages as if they were sent by the last relay.

log-iw-size()
Type: number
Default: 100

Description: The size of the initial window, this value is used during flow control. For details on flow control, see Managing incoming and outgoing messages with flow-control.

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
tags()
Type: string
Default:

Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in syslog-ng 3.1 and later.

use-syslogng-pid()
Type: yes | no
Default: no

Description: If the value of this option is yes, then the pid value of the message will be overridden with the pid of the running syslog-ng PE process.

python-fetcher: writing fetcher-style Python sources

The Python source allows you to write your own source in Python.

You can write two different type of sources in Python:

  • Server-style sources that receives messages. Write server-style sources if you want to use an event-loop based, nonblocking server framework in Python, or if you want to implement a custom loop.

  • Fetcher-style sources that actively fetch messages. In general, write fetcher-style sources (for example, when using simple blocking APIs), unless you explicitly need a server-style source.

This section describes fetcher-style sources. For details on server-style sources, see python: writing server-style Python sources.

The following points apply to using Python blocks in syslog-ng PE in general:

  • Only the default Python modules are available (that is, you cannot import external Python modules, and One Identity does not support using external Python modules).

  • The syslog-ng PE application uses its own Python interpreter (shipped with the default syslog-ng PE installation) instead of the system's Python interpreter.

  • The syslog-ng PE application is shipped with Python version 3.8.

  • The Python block must be a top-level block in the syslog-ng PE configuration file.

  • If you store the Python code in a separate Python file and only include it in the syslog-ng PE configuration file, make sure that the PYTHON_PATH environment variable includes the path to the Python file, and export the PYTHON_PATH environment variable. For example, if you start syslog-ng PE manually from a terminal and you store your Python files in the /opt/syslog-ng/etc directory, use the following command: export PYTHONPATH=/opt/syslog-ng/etc

    In production, when syslog-ng PE starts on boot, you must configure your startup script to include the Python path. The exact method depends on your operating system. For recent Red Hat Enterprise Linux, Fedora, and CentOS distributions that use systemd, the systemctl command sources the /etc/sysconfig/syslog-ng file before starting syslog-ng PE. (On openSUSE and SLES, /etc/sysconfig/syslog file.) Append the following line to the end of this file: PYTHONPATH="<path-to-your-python-file>", for example, PYTHONPATH="/opt/syslog-ng/etc"

  • The Python object is initiated every time when syslog-ng PE is started or reloaded.

    Caution:

    If you reload syslog-ng PE, existing Python objects are destroyed, therefore the context and state information of Python blocks is lost. Log rotation and updating the configuration of syslog-ng PE typically involves a reload.

  • The Python block can contain multiple Python functions.

  • Using Python code in syslog-ng PE can significantly decrease the performance of syslog-ng PE, especially if the Python code is slow. In general, the features of syslog-ng PE are implemented in C, and are faster than implementations of the same or similar features in Python.

  • Validate and lint the Python code before using it. The syslog-ng PE application does not do any of this.

  • Python error messages are available in the internal() source of syslog-ng PE.

  • You can access the name-value pairs of syslog-ng PE directly through a message object or a dictionary.

  • To help debugging and troubleshooting your Python code, you can send log messages to the internal() source of syslog-ng PE. For details, see Logging from your Python code.

  • Caution:

    Python modules are using variable types from syslog-ng PE 7.0.34. If you are using Python modules, revisit your code and configuration, and modify the parameters to reflect the correct types.

    You have to set the correct types during declaration.

    For more information, see Knowledge base article #4372255.

  • Support disclaimer

    Caution:

    This is a Preview Feature, which provides an insight to planned enhancements to functionality in the product. Consider this Preview Feature a work in progress, as it may not represent the final design and functionality.

    This feature has completed QA release testing, but 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.

    One Identity recommends the following:

    • Consider the potential risks when using this functionality in a production environment.
    • Consider the Support Policy on Product Preview Features before 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 application 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.

    Support Policy on Product Preview Features

    The One Identity Support Team will:

    • Accept and review each service request opened regarding a Preview Feature.

    • Consider all service requests relating to a Preview Features as severity level 3.

    • Provide best effort support to resolve any issues relating to a Preview Feature.

    • Work with customers to log any product defects or enhancements relating to Preview Features.

    • Not accept requests for escalations regarding Preview Features.

    • Not provide after-hours support for Preview Features.

    Using Python in syslog-ng PE is recommended only if you are familiar with both Python and syslog-ng PE. One Identity is not responsible for the quality, resource requirements, or any bugs in the Python code, nor any syslog-ng PE crashes, message losses, or any other damage caused by the improper use of this feature, unless explicitly stated in a contract with One Identity.

Declaration

Python sources consist of two parts. The first is a syslog-ng PE source object that you define in your syslog-ng PE configuration and use in the log path. This object references a Python class, which is the second part of the Python source. The Python class receives or fetches the log messages, and can do virtually anything that you can code in Python. You can either embed the Python class into your syslog-ng PE configuration file, or store it in an external Python file.

source <name_of_the_python_source>{
    python-fetcher(
        class("<name_of_the_python_class_executed_by_the_source>")
    );
};

python {
from syslogng import LogFetcher
from syslogng import LogMessage

class <name_of_the_python_class_executed_by_the_source>(LogFetcher):
    def init(self, options): # optional
        print("init")
        print(options)
        return True

    def deinit(self): # optional
        print("deinit")

    def open(self): # optional
        print("open")
        return True

    def fetch(self): # mandatory
        print("fetch")
        # return LogFetcher.FETCH_ERROR,
        # return LogFetcher.FETCH_NOT_CONNECTED,
        return LogFetcher.FETCH_SUCCESS, msg

    def request_exit(self):
        print("request_exit")
        # If your fetching method is blocking, do something to break it
        # For example, if it reads a socket: socket.shutdown()

    def close(self): # optional
        print("close")
};
Methods of the python-fetcher() source

Fetcher-style Python sources must be inherited from the syslogng.LogFetcher class, and must implement at least the fetch method. Multiple inheritance is allowed, but only for pure Python super classes.

For fetcher-style Python sources, syslog-ng PE handles the event loop and the scheduling automatically. You can use simple blocking server/client libraries to receive or fetch logs.

You can retrieve messages using the fetch() method.

init(self, options) method (optional)

The syslog-ng PE application initializes Python objects every time when it is started or reloaded. The init method is executed as part of the initialization. You can perform any initialization steps that are necessary for your source to work.

Caution:

If you reload syslog-ng PE, existing Python objects are destroyed, therefore the context and state information of Python blocks is lost. Log rotation and updating the configuration of syslog-ng PE typically involves a reload.

When this method returns with False, syslog-ng PE does not start. It can be used to check options and return False when they prevent the successful start of the source.

options: This optional argument contains the contents of the options() parameter of the syslog-ng PE configuration object as a Python dictionary.

open(self) method (optional)

The open(self) method opens the resources required for the source, for example, it initiates a connection to the target service. It is called after init() when syslog-ng PE is started or reloaded. If fetch() returns with an error, syslog-ng PE calls the close() and open() methods before trying to fetch a new message.

If open() fails, it should return the False value. In this case, syslog-ng PE retries it every time-reopen() seconds. By default, this is 1 second for Python sources and destinations, the value of time-reopen() is not inherited from the global option. For details, see Error handling in the python() destination.

fetch(self) method (mandatory)

Use the fetch method to fetch messages and pass them to the log paths.

For details on parsing messages, see Python LogMessage API.

The fetch method must return one of the following values:

  • LogFetcher.FETCH_ERROR: Fetching new messages failed, syslog-ng PE calls the close and open methods.

  • LogFetcher.FETCH_NOT_CONNECTED: Could not access the source, syslog-ng PE calls the open method.

  • LogFetcher.FETCH_SUCCESS, msg: Post the message returned as the second argument.

request_exit(self) method (optional)

If you use blocking operations within the fetch() method, use request_exit() to interrupt those operations (for example, to shut down a socket), otherwise syslog-ng PE is not able to stop. Note that syslog-ng PE calls the request_exit method from a thread different from the source thread.

close(self) method (optional)

Close the connection to the target service. Usually it is called right before deinit() when stopping or reloading syslog-ng PE. It is also called when fecth() fails.

The deinit(self) method (optional)

This method is executed when syslog-ng PE is stopped or reloaded. This method does not return a value.

Caution:

If you reload syslog-ng PE, existing Python objects are destroyed, therefore the context and state information of Python blocks is lost. Log rotation and updating the configuration of syslog-ng PE typically involves a reload.

For the list of available optional parameters, see python() and python-fetcher() source options.

Python LogMessage API

The LogMessage API allows you to create LogMessage objects in Python sources, parse syslog messages, and set the various fields of the log message.

LogMessage() method: Create log message objects

You can use the LogMessage() method to create a structured log message instance. For example:

from syslogng import LogMessage

msg = LogMessage() # Initialize an empty message with default values (recvd timestamp, rcptid, hostid, ...)
msg = LogMessage("string or bytes-like object") # Initialize a message and set its ${MESSAGE} field to the specified argument

You can also explicitly set the different values of the log message. For example:

msg["MESSAGE"] = "message"
msg["HOST"] = "hostname"

You can set certain special field (timestamp, priority) by using specific methods.

Note the following points when creating a log message:

  • When setting the hostname, syslog-ng PE takes the following hostname-related options of the configuration into account: chain-hostnames(), keep-hostname(), use-dns(), and use-fqdn().

  • Python sources ignore the log-msg-size() option.

  • The syslog-ng PE application accepts only one message from every LogSource::post_message() or fetch() call, batching is currently not supported. If your Python code accepts batches of messages, you must pass them to syslog-ng PE one-by-one. Similarly, if you need to split messages in the source, you must do so in your Python code, and pass the messages separately.

  • Do not reuse or store LogMessage objects after posting (calling post_message()) or returning the message from fetch().

parse() method: Parse syslog messages

The parse() method allows you to parse incoming messages as syslog messages. By default, the parse() method attempts to parse the message as an IETF-syslog (RFC5424) log message. If that fails, it parses the log message as a BSD-syslog (RFC3164) log message. Note that syslog-ng PE takes the parsing-related options of the configuration into account: flags(), keep-hostname(), recv-time-zone().

If keep-hostname() is set to no, syslog-ng PE ignores the hostname set in the message, and uses the IP address of the syslog-ng PE host as the hostname (to use the hostname instead of the IP address, set the use-dns() or use-fqdn() options in the Python source).

msg_ietf = LogMessage.parse('<165>1 2003-10-11T22:14:15.003Z mymachine.example.com evntslog - ID47 [exampleSDID@32473 iut="3" eventSource="Application" eventID="1011"] An application event log entry', self.parse_options)
msg_bsd = LogMessage.parse('<34>Oct 11 22:14:15 mymachine su: \'su root\' failed for lonvick on /dev/pts/8', self.parse_options)
set_pri() method

You can set the priority of the message with the set_pri() method.

msg.set_pri(165)
set_timestamp() method

You can use the set_timestamp() method to set the date and time of the log message.

timestamp = datetime.fromisoformat("2018-09-11T14:49:02.100+02:00")
msg.set_timestamp(timestamp) # datetime object, includes timezone information

In Python 2, timezone information cannot be attached to the datetime instance without using an external library. The syslog-ng PE represents naive datetime objects in UTC.

In Python 3, naive and timezone-aware datetime objects are both supported.

python() and python-fetcher() source options

The python() and python-fetcher() drivers have the following options.

class()
Type: string
Default: N/A

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

python(
    class("MyPythonSource")
);

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.MyPythonSource")
);

For details, see Python code in external files

flags()
Type: assume-utf8, empty-lines, expect-hostname, guess-timezone, kernel, no-hostname, no-multi-line, no-parse, sanitize-utf8, store-legacy-msghdr, store-raw-message, syslog-protocol, validate-utf8
Default: empty set

Description: Specifies the log parsing options of the source.

  • assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.

  • empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, syslog-ng PE removes empty lines automatically.

  • expect-hostname: If the expect-hostname flag is enabled, syslog-ng PE will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.

  • kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.

  • no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way syslog-ng PE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:

    source s_dell {
        network(
            port(2000)
            flags(no-hostname)
        );
    };
  • no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.

  • no-parse: By default, syslog-ng PE parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The syslog-ng PE application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.

    If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, syslog-ng PE generates a new syslog header (timestamp, host, and so on) automatically. Note that since flags(no-parse) disables message parsing, it interferes with other flags, for example, disables flags(no-multi-line).

  • dont-store-legacy-msghdr: By default, syslog-ng stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (syslog-ng automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.

  • sanitize-utf8: When using the sanitize-utf8 flag, syslog-ng PE converts non-UTF-8 input to an escaped form, which is valid UTF-8.

  • store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another syslog-ng node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 7.0.9 and later.

  • syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.

  • validate-utf8: The validate-utf8 flag enables encoding-verification for messages formatted according to the new IETF syslog standard (for details, see IETF-syslog messages). If theBOM1character is missing, but the message is otherwise UTF-8 compliant, syslog-ng automatically adds the BOM character to the message.

The flags and the hostname-related options (for example, use-dns) set in the configuration file influence the behavior of the LogMessage.parse() method of the Python source. They have no effect if you set the message or the hostname directly, without using LogMessage.parse().

keep-hostname()
Type: yes or no
Default: no

Description: Enable or disable hostname rewriting.

  • If enabled (keep-hostname(yes)), syslog-ng PE assumes that the incoming log message was sent by the host specified in the HOST field of the message.

  • If disabled (keep-hostname(no)), syslog-ng PE rewrites the HOST field of the message, either to the IP address (if the use-dns() parameter is set to no), or to the hostname (if the use-dns() parameter is set to yes and the IP address can be resolved to a hostname) of the host sending the message to syslog-ng PE. For details on using name resolution in syslog-ng PE, see Using name resolution in syslog-ng.

NOTE: If the log message does not contain a hostname in its HOST field, syslog-ng PE automatically adds a hostname to the message.

  • For messages received from the network, this hostname is the address of the host that sent the message (this means the address of the last hop if the message was transferred via a relay).

  • For messages received from the local host, syslog-ng PE adds the name of the host.

This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

NOTE: When relaying messages, enable this option on the syslog-ng PE server and also on every relay, otherwise syslog-ng PE will treat incoming messages as if they were sent by the last relay.

log-iw-size()
Type: number
Default: 100

Description: The size of the initial window, this value is used during flow control. For details on flow control, see Managing incoming and outgoing messages with flow-control.

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
tags()
Type: string
Default:

Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in syslog-ng 3.1 and later.

use-syslogng-pid()
Type: yes | no
Default: no

Description: If the value of this option is yes, then the pid value of the message will be overridden with the pid of the running syslog-ng PE process.

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