syslog-ng Open Source Edition 3.21 - 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 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) 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 (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 Creative Commons Attribution Non-commercial No Derivatives (by-nc-nd) License

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 3.21?

Version 3.21 of syslog-ng Open Source Edition includes the following main features.

HTTP-based Elasticsearch destination

Add a native, HTTP based destination Elasticsearch, called elasticsearch-http(), as an alternative of the Java-based destination. This destination does not requires Java, and has smaller resource requirements. Eventually, we expect this destination to replace the Java implementation. For details, see "elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API" in the Administration Guide.

C-based Kafka destination

Add a native destination based on the librdkafka library, as an alternative of the Java-based destination. This destination does not requires Java, and has smaller resource requirements. Eventually, we expect this destination to replace the Java implementation. Note that this destination requires a very recent version of librdkafka. For details, see "kafka: Publishing messages to Apache Kafka (C implementation)" in the Administration Guide.

New parser

The CheckPoint LogExporter parser can parse CheckPoint log messages, and join the related multiline log messages into a single log message. For details, see Administration Guide.

New template functions

The $(implode) and $(explode) template functions allow you to split and join strings based on a simple separator. The exploded array is represented as a syslog-ng list that can be manipulated with the $(list-*) template functions. For details, see "Template functions of syslog-ng OSE" in the Administration Guide.

  • The amqp() destination now supports the heartbeat and the external authentication mechanisms of AMQP. For details, see "amqp: Publishing messages using AMQP" in the Administration Guide.

  • The graylog2() destination now supports the TLS and the UDP transport mechanisms. For details, see "Sending logs to Graylog" in the Administration Guide.

  • The apache-accesslog-parser() now supports vhost:port as the first field of the log message in common and combined log formats.

  • The grouping-by() parser now can order the messages of the context by using the sort-key() option.

  • You can automatically determine the timezone of an incoming log message if the incoming stream is close to real time, and the timezone information is missing from the timestamp. You can enable this feature by using the flags(guess-timezone) option in sources and the date-parser().

  • Until now, the syslog() source automatically closed the connection to the sender if it received a message that was longer than the value of the log-msg-size() option. From now on, if you set the trim-large-messages() option to yes, syslog-ng OSE only truncates the message to log-msg-size(), and sends a log message to the internal() source as notification about the truncation.

  • You can now set the maximum size of spoofed datagrams in udp() destinations by using the spoof-source-max-msglen() option. Earlier, this size was hard-wired to 1024 bytes.

  • The --omit-empty-values option for destinations and template functions using value-pairs allows you to skip empty value-pairs in the output.

  • When parsing and classifying log messages with db-parser(), syslog-ng OSE so far used the value of the $PROGRAM field to determine which patterns to match to the incoming message. Now you can use program-template() option to customize the value which selects the patterns to use. For details, see "Using pattern databases" in the Administration Guide.

  • The pdbtool merge tool can now sort the resulting database using the sort option. For details, see the pdbtool manual page.

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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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