syslog-ng Open Source Edition 3.26 - 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 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

Options of geoip parsers

The geoip parser has the following options.

Synopsis: prefix()

Description: Insert a prefix before the name part of the parsed name-value pairs to help further processing. For example:

  • To insert the my-parsed-data. prefix, use the prefix(my-parsed-data.) option.

  • To refer to a particular data that has a prefix, use the prefix in the name of the macro, for example, ${}.

  • If you forward the parsed messages using the IETF-syslog protocol, you can insert all the parsed data into the SDATA part of the message using the prefix( option.

Names starting with a dot (for example, .example) are reserved for use by syslog-ng OSE. If you use such a macro name as the name of a parsed value, it will attempt to replace the original value of the macro (note that only soft macros can be overwritten, see Hard versus soft macros for details). To avoid such problems, use a prefix when naming the parsed values, for example, prefix(my-parsed-data.)

For example, to insert the geoip. prefix, use the prefix(.geoip.) option. To refer to a particular data when using a prefix, use the prefix in the name of the macro, for example, ${geoip.country_code} .

Synopsis: database()
Default: /usr/share/GeoIP/GeoIP.dat

Description: The full path to the GeoIP database to use. Note that syslog-ng OSE must have the required privileges to read this file. Do not modify or delete this file while syslog-ng OSE is running, it can crash syslog-ng OSE.

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Looking up GeoIP2 data from IP addresses

The syslog-ng OSE application can lookup IP addresses from an offline GeoIP2 database, and make the retrieved data available in name-value pairs. Depending on the database used, you can access country code, longitude, and latitude information and so on.

The syslog-ng OSE application works with the Country and the City version of the GeoIP2 database, both free and the commercial editions. The syslog-ng OSE application works with the mmdb (GeoIP2) format of these databases. Other formats, like csv are not supported.


To access longitude and latitude information, download the City version of the GeoIP2 database.

There are two types of GeoIP2 databases available.

  • GeoLite2 City:

    • free of charge

    • less accurate

  • GeoIP2 City:

    • has to be purchased

    • more accurate

Unzip the downloaded database (for example, to the /usr/share/GeoIP2/GeoIP2City.mmdb file). This path will be used later in the configuration.

Starting with version 3.24, syslog-ng OSE tries to automatically detect the location of the database. If that is successful, the database() option is not mandatory.

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Referring to parts of the message as a macro

You can refer to the separated parts of the message using the key of the value as a macro. For example, if the message contains KEY1=value1,KEY2=value2, you can refer to the values as ${KEY1} and ${KEY2}.

for example, if the default prefix (.geoip2) is used, you can determine the country code using ${}.

To look up all keys:

  1. Install the mmdb-bin package.

    After installing this package, you will be able to use the mmdblookup command.


    The name of the package depends on the Linux distribution. The package mentioned in this example is on Ubuntu.

  2. Create a dump using the following command: mmdblookup --file GeoLite2-City.mmdb --ip <your-IP-address>

    The resulting dump file will contain the keys that you can use.

For a more complete list of keys, you can also check the GeoIP2 City and Country CSV Databases. However, note that the syslog-ng OSE application works with the mmdb (GeoIP2) format of these databases. Other formats, like csv are not supported.

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Using the GeoIP2 parser

parser parser_name {

In the following example, syslog-ng OSE retrieves the GeoIP2 data of the IP address contained in the ${HOST} field of the incoming message (assuming that in this case the ${HOST} field contains an IP address), and includes the data (prefixed with the geoip2 string) in the output JSON message.

@version: 3.11

options {

source s_file {

parser p_geoip2 {
        prefix( "geoip2." )
        database( "/usr/share/GeoIP2/GeoLiteCity.dat" )

destination d_file {
        template("$(format-json --scope core --key geoip2*)\n")

log {

For example, for the <38>2017-05-24T13:09:46 prg00000[1234]: test message message the output will look like:

<38>1 2017-05-24T13:09:46+02:00 prg00000 1234 - [meta sequenceId="3"] {"geoip2":{"subdivisions":{"0":{"names":{"en":"Budapest"},"iso_code":"BU","geoname_id":"3054638"}},"registered_country":{"names":{"en":"Hungary"},"iso_code":"HU","geoname_id":"719819"},"postal":{"code":"1063"},"location":{"time_zone":"Europe/Budapest","longitude":"19.070200","latitude":"47.510200","accuracy_radius":"5"},"country":{"names":{"en":"Hungary"},"iso_code":"HU","geoname_id":"719819"},"continent":{"names":{"en":"Europe"},"geoname_id":"6255148","code":"EU"},"city":{"names":{"en":"Budapest"},"geoname_id":"3054643"}},"PROGRAM":"prg00000","PRIORITY":"info","PID":"1234","MESSAGE":"test message","HOST":"","FACILITY":"auth","DATE":"May 24 13:09:46"}

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