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syslog-ng Open Source Edition 3.30 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng The syslog-ng OSE quick-start guide The syslog-ng OSE configuration file source: Read, receive, and collect log messages
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) nodejs: Receiving JSON messages from nodejs applications mbox: Converting local email messages to log messages osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes pacct: Collecting process accounting logs on Linux program: Receiving messages from external applications python: writing server-style Python sources python-fetcher: writing fetcher-style Python sources snmptrap: Read Net-SNMP traps sun-streams: Collecting messages on Sun Solaris 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— OBSOLETE unix-stream, unix-dgram: Collecting messages from UNIX domain sockets stdin: Collecting messages from the standard input stream
destination: Forward, send, and store log messages
amqp: Publishing messages using AMQP collectd: sending metrics to collectd elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API file: Storing messages in plain-text files graphite: Sending metrics to Graphite Sending logs to Graylog hdfs: Storing messages on the Hadoop Distributed File System (HDFS) Posting messages over HTTP http: Posting messages over HTTP without Java kafka: Publishing messages to Apache Kafka (Java implementation) kafka: Publishing messages to Apache Kafka (C implementation, using the librdkafka client) loggly: Using Loggly logmatic: Using mongodb: Storing messages in a MongoDB database network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) osquery: Sending log messages to osquery's syslog table pipe: Sending messages to named pipes program: Sending messages to external applications pseudofile() python: writing custom Python destinations redis: Storing name-value pairs in Redis riemann: Monitoring your data with Riemann slack: Sending alerts and notifications to a Slack channel smtp: Generating SMTP messages (email) from logs snmp: Sending SNMP traps Splunk: Sending log messages to Splunk sql: Storing messages in an SQL database stomp: Publishing messages using STOMP Sumo Logic destinations: sumologic-http() and sumologic-syslog() 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) Telegram: Sending messages to Telegram unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal: usertty() destination Write your own custom destination in Java or Python Client-side failover
log: Filter and route log messages using log paths, flags, and filters Global options of syslog-ng OSE TLS-encrypted message transfer template and rewrite: Format, modify, and manipulate log messages parser: Parse and segment structured messages db-parser: Process message content with a pattern database (patterndb) Correlating log messages Enriching log messages with external data Statistics of syslog-ng Multithreading and scaling in syslog-ng OSE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd) License Glossary

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 OSE 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 OSE 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 OSE 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 OSE 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 OSE ignores the hostname set in the message, and uses the IP address of the syslog-ng OSE 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 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.

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 OSE represents naive datetime objects in UTC.

python() and python-fetcher() source options

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

Type: string
Default: N/A

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


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:


For details, see Python code in external files

Type: integer [seconds]
Default: -1 (disabled)

Description: If the fetch method of a python-fetcher() source returns with the LogFetcher.FETCH_NO_DATA constant, the source waits time-reopen() seconds before calling the fetch method again. If you want to call the fetch method sooner, set the fetch-no-data-delay() option to the number of seconds to wait before calling the fetch method.

Type: assume-utf8, empty-lines, expect-hostname, 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 OSE removes empty lines automatically.

  • expect-hostname: If the expect-hostname flag is enabled, syslog-ng OSE 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.

  • guess-timezone: Attempt to guess the timezone of the message if this information is not available in the message. Works when the incoming message stream is close to real time, and the timezone information is missing from the timestamp.

  • 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 OSE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:

    source s_dell {
  • 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 OSE 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 OSE 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 OSE 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 OSE 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 3.16 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 the BOM1 character 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().

Type: yes or no
Default: no

Description: Enable or disable hostname rewriting.

  • If enabled (keep-hostname(yes)), syslog-ng OSE 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 OSE 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 OSE. For details on using name resolution in syslog-ng OSE, see Using name resolution in syslog-ng.


NOTE: If the log message does not contain a hostname in its HOST field, syslog-ng OSE 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 OSE 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 OSE server and also on every relay, otherwise syslog-ng OSE will treat incoming messages as if they were sent by the last relay.

Type: number
Default: 100

Description: The size of the initial window, this value is used during flow-control. Its value cannot be lower than 100, unless the dynamic-window-size() option is enabled. For details on flow-control, see Managing incoming and outgoing messages with flow-control.

Type: list of python modules
Default: empty list

Description: The syslog-ng OSE application imports Python modules specified in this option, before importing the code of the Python class. This option has effect only when the Python class is provided in an external Python file. This option has no effect when the Python class is provided within the syslog-ng OSE configuration file (in a python{} block). You can use the loaders() option to modify the import mechanism that imports Python class. For example, that way you can use hy in your Python class.

python(class(usermodule.HyParser) loaders(hy))
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.

        "host" ""
        "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"])

NOTE: From version 3.27, syslog-ng OSE supports the arrow syntax for declaring custom Java and Python options. You can alternatively declare them using a similar syntax:

  "host" => "localhost"
  "port" => "1883"
  "otheroption" => "value"
Type: string

Description:If you receive the following error message during syslog-ng OSE 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 happens 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 3.26, syslog-ng OSE 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 OSE configuration, add a unique persist-name() to each source or destination, otherwise syslog-ng OSE 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):
    def generate_persist_name(options):
        return options["port"]
    def run(self):
    def request_exit(self):
Type: string

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.

Type: name of the timezone, or the timezone offset

Description: The default timezone for messages read from the source. Applies only if no timezone is specified within the message itself.

The timezone can be specified by using the name, for example, time-zone("Europe/Budapest")), or as the timezone offset in +/-HH:MM format, for example, +01:00). On Linux and UNIX platforms, the valid timezone names are listed under the /usr/share/zoneinfo directory.


This option is available only when using Python 3.

python-fetcher: writing fetcher-style Python sources

The Python source allows you to write your own source in Python. You can import external Python modules to receive or fetch the messages. Since many services have a Python library, the Python source makes integrating syslog-ng OSE very easy and quick.

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 OSE in general:
  • Python parsers and template functions are available in syslog-ng OSE version 3.10 and later.

    Python destinations and sources are available in syslog-ng OSE version 3.18 and later.

  • Supported Python versions: 2.7 and 3.4+ (if you are using pre-built binaries, check the dependencies of the package to find out which Python version it was compiled with).

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

  • If you store the Python code in a separate Python file and only include it in the syslog-ng OSE 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 OSE 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 OSE 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 OSE. (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 OSE is started or reloaded.


    If you reload syslog-ng OSE, 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 OSE typically involves a reload.

  • The Python block can contain multiple Python functions.

  • Using Python code in syslog-ng OSE can significantly decrease the performance of syslog-ng OSE, especially if the Python code is slow. In general, the features of syslog-ng OSE 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 OSE application does not do any of this.

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

  • You can access the name-value pairs of syslog-ng OSE 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 OSE. For details, see Logging from your Python code.


Python sources consist of two parts. The first is a syslog-ng OSE source object that you define in your syslog-ng OSE 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 OSE configuration file, or store it in an external Python file.

source <name_of_the_python_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
        return True

    def deinit(self): # optional

    def open(self): # optional
        return True

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

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

    def close(self): # optional
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 OSE 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 OSE 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.


If you reload syslog-ng OSE, 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 OSE typically involves a reload.

When this method returns with False, syslog-ng OSE 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 OSE 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 OSE is started or reloaded. If fetch() returns with an error, syslog-ng OSE 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 OSE 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 OSE calls the close and open methods.

  • LogFetcher.FETCH_NO_DATA: There was not any data available. The source waits before calling the fetch method again. The wait time is equal to time-reopen() by default, but you can override it by setting the fetch-no-data-delay() option in the source.

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

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

  • LogFetcher.FETCH_TRY_AGAIN: The fetcher could not provide a message this time, but will make the source call the fetch method as soon as possible.

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 OSE is not able to stop. Note that syslog-ng OSE 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 OSE. It is also called when fecth() fails.

The deinit(self) method (optional)

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


If you reload syslog-ng OSE, 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 OSE typically involves a reload.

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

snmptrap: Read Net-SNMP traps

Using the snmptrap() source, you can read and parse the SNMP traps of the Net-SNMP's snmptrapd application. syslog-ng OSE can read these traps from a log file, and extract their content into name-value pairs, making it easy to forward them as a structured log message (for example, in JSON format). The syslog-ng OSE application automatically adds the .snmp. prefix to the name of the fields the extracted from the message.

The snmptrap() source is available in syslog-ng OSE version 3.10 and later.

  • The snmptrap() source has only the options listed in snmptrap() source options. Other options commonly available in other source drivers are not supported.

  • In addition to traps, the log of snmptrapd may contain other messages (for example, daemon start/stop information, debug logs) as well. Currently syslog-ng OSE discards these messages.

  • The syslog-ng OSE application cannot resolve OIDs, you have to configure snmptrapd to do so. Note that because of a bug, if snmptrapd does not escape String values in the VarBindList if it can resolve an OID to a symbolic name. As a result, syslog-ng OSE cannot process traps that contain the = in the value of the string. To overcome this problem, disable resolving OIDs in snmptrapd. For details, see the documentation of snmptrapd.

  • The colon (:) character is commonly used in SNMP traps. However, this character cannot be used in the name of syslog-ng OSE macros (name-value pairs). Therefore, the syslog-ng OSE application automatically replaces all consecutive : characters with a single underscore (_) character. For example, you can reference the value of the NET-SNMP-EXAMPLES-MIB::netSnmpExampleString key using the ${NET-SNMP-EXAMPLES-MIB_netSnmpExampleString} macro.

    Note that this affects only name-value pairs (macros). The generated message always contains the original name of the key.

  • Configure snmptrapd to log into a file.

  • If you use SMIv1 traps, include the following format string in the configuration file of snmptrapd:

    format1 %.4y-%.2m-%.2l %.2h:%.2j:%.2k %B [%b]: %N\n\t%W Trap (%q) Uptime: %#T\n%v\n
  • If you use SMIv2 traps, use the default format. The snmptrap() source of syslog-ng OSE expects this default format:

    format2 %.4y-%.2m-%.2l %.2h:%.2j:%.2k %B [%b]:\n%v\n
  • Beacause of an snmptrapd bug, if you specify the filename in the configuration file with logOption, you must also specify another output as a command line argument (-Lf, -Ls). Otherwise, snmptrapd will not apply the the trap format.

To use the snmptrap() driver, the scl.conf file must be included in your syslog-ng OSE configuration:

@include "scl.conf"
Example: Using the snmptrap() driver

A sample snmptrapd configuration:

authCommunity log,execute,net public
format1 %.4y-%.2m-%.2l %.2h:%.2j:%.2k %B [%b]: %N\n\t%W Trap (%q) Uptime: %#T\n%v\n
outputOption s

Starting snmptrapd: snmptrapd -A -Lf /var/log/snmptrapd.log

Sending a sample V2 trap message: snmptrap -v2c -c public 666 NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification netSnmpExampleHeartbeatRate i 60 netSnmpExampleString s "string". From this trap, syslog-ng OSE receives the following input:

2017-05-23 15:29:40 localhost [UDP: []:59993->[]:162]:
SNMPv2-SMI::mib- = Timeticks: (666) 0:00:06.66   SNMPv2-SMI::snmpModules. = OID: NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification     NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate = INTEGER: 60        NET-SNMP-EXAMPLES-MIB::netSnmpExampleString = STRING: string

The following syslog-ng OSE configuration sample uses the default settings of the driver, reading SNMP traps from the /var/log/snmptrapd.log file, and writes the log messages generated from the traps into a file.

@include "scl.conf"
log {
  source {
  destination {

From the trap, syslog-ng OSE writes the following into the log file:

May 23 15:29:40 myhostname snmptrapd: hostname='localhost', transport_info='UDP: []:59993->[]:162', SNMPv2-SMI::mib-'(666) 0:00:06.66', SNMPv2-SMI::snmpModules.'NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification', NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate='60', NET-SNMP-EXAMPLES-MIB::netSnmpExampleString='string'

Using the same input trap, the following configuration example formats the SNMP traps as JSON messages.

@include "scl.conf"
log {
  source {

  destination {
    file("/var/log/example.log" template("$(format-json --scope dot-nv-pairs)\n"));

The previous trap formatted as JSON:

      "transport_info":"UDP: []:59993->[]:162",
               "0":"(666) 0:00:06.66"
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