syslog-ng Open Source Edition 3.18 - 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 e-mail 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 elasticsearch: Sending messages directly to Elasticsearch version 1.x (DEPRECATED) elasticsearch2: Sending logs directly to Elasticsearch and Kibana 2.0 or higher 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 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 smtp: Generating SMTP messages (e-mail) from logs Splunk: Sending log messages to Splunk sql: Storing messages in an SQL database stomp: Publishing messages using STOMP syslog: Sending messages to a remote logserver using the IETF-syslog protocol syslog-ng: Forwarding messages and tags 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 Third-party contributions Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd) License About us

What syslog-ng is not

The syslog-ng application is not log analysis software. It can filter log messages and select only the ones matching certain criteria. It can even convert the messages and restructure them to a predefined format, or parse the messages and segment them into different fields. But syslog-ng cannot interpret and analyze the meaning behind the messages, or recognize patterns in the occurrence of different messages.

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Why is syslog-ng needed?

Log messages contain information about the events happening on the hosts. Monitoring system events is essential for security and system health monitoring reasons.

The original syslog protocol separates messages based on the priority of the message and the facility sending the message. These two parameters alone are often inadequate to consistently classify messages, as many applications might use the same facility, and the facility itself is not even included in the log message. To make things worse, many log messages contain unimportant information. The syslog-ng application helps you to select only the really interesting messages, and forward them to a central server.

Company policies or other regulations often require log messages to be archived. Storing the important messages in a central location greatly simplifies this process.

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What is new in syslog-ng Open Source Edition 3.18?

Version 3.18 of syslog-ng Open Source Edition includes the following main features.

Batch support in the http() destination driver

The http() destination can now send a batch of log messages in a single HTTP request, greatly improving the performance. In addition, this feature also allows you to post proper JSON-encoded arrays as POST payloads, which is required by several REST APIs. For details, see Administration Guide.

Write your own destination in Python

Extending syslog-ng OSE in Python has been supported for several releases, but so far this feature was mostly undocumented. Now you can find more details about this feature in "python: writing custom Python destinations" in the Administration Guide.

Write your own message source in Python

Starting with syslog-ng OSE version 3.18, you can write custom message sources in Python. Both server-style and fetcher-style sources are supported. For more details, see "python: writing server-style Python sources" in the Administration Guide and "python-fetcher: writing fetcher-style Python sources" in the Administration Guide.

  • When hdfs-append-enabled is set to true, syslog-ng OSE will append new data to the end of an already existing HDFS file. Note that in this case, archiving is automatically disabled, and syslog-ng OSE will ignore the hdfs-archive-dir option.

  • The hdfs destination now supports the time-reap() option.

  • The urlencode() template function has been renamed to url-encode(). Also, the telegram() destination now automatically encodes the messages.

  • New template functions are available: url-decode() and base64-encode(). For details, see "Template functions of syslog-ng OSE" in the Administration Guide.

  • The syslog-ng-ctl config command can display the contents of the configuration file that syslog-ng OSE is currently running.

  • The rekey option of value-pairs() now supports a new transformation: shift-levels. It cuts dot-delimited "levels" in the name (including the initial dot). For example, --shift-levels 2 deletes the prefix up to the second dot in the name of the key: .iptables.SRC becomes SRC

    For details, see "value-pairs()" in the Administration Guide.

  • The value-pairs() option now has a new scope: none. This scope resets previously added scopes, making it possible to get remove automatically added name-value pairs from the scope.

    For details, see "value-pairs()" in the Administration Guide.

  • When receiving messages with the default-network-drivers() source, syslog-ng OSE now automatically sets the ${} name-value pair to the name of the application that sent the log message.

    For details, see "default-network-drivers: Receive and parse common syslog messages" in the Administration Guide.

Deprecated features

The elasticsearch() destination has been deprecated, because it supports only ElasticSearch version 1.x, which has been End-of-Life since January, 2017. Use the elasticsearch2() destination instead.

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Who uses syslog-ng?

The syslog-ng application is used worldwide by companies and institutions who collect and manage the logs of several hosts, and want to store them in a centralized, organized way. Using syslog-ng is particularly advantageous for:

  • Internet Service Providers

  • Financial institutions and companies requiring policy compliance

  • Server, web, and application hosting companies

  • Datacenters

  • Wide area network (WAN) operators

  • Server farm administrators.

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