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syslog-ng Open Source Edition 3.17 - 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 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 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 Logmatic.io 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() 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 Third-party contributions

MySQL-specific interaction methods

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.


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MsSQL-specific interaction methods

In SQL Server 2005 this restriction is lifted - kind of. The total length of all key columns in an index cannot exceed 900 bytes.

If you are using null() in your configuration, be sure that the columns allow NULL to insert. Give the column as the following example: "datetime varchar(16) NULL".

The date format used by the MSSQL database must be explicitly set in the /etc/locales.conf file of the syslog-ng server. [default] date = "%Y-%m-%d %H:%M:%S".


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sql() destination options

This driver sends messages into an SQL database. The sql() destination has the following options:

columns()
Type: string list
Default: "date", "facility", "level", "host", "program", "pid", "message"

Description: Name of the columns storing the data in fieldname [dbtype] format. The [dbtype] parameter is optional, and specifies the type of the field. By default, syslog-ng OSE creates text columns. Note that not every database engine can index text fields.

Caution:

The following column types cannot be used in MSSQL destinations: nchar, nvarchar, ntext, and xml.

create-statement-append()
Type: string
Default: empty string

Description: Specifies additional SQL options that are appended to the CREATE statement. That way you can customize what happens when syslog-ng OSE creates a new table in the database. Consult the documentation of your database server for details on the available options. Syntax:

create-statement-append(<options-to-append>)

For example, you can appends the ROW_FORMAT=COMPRESSED option to MySQL create table statements:

create-statement-append(ROW_FORMAT=COMPRESSED)
database()
Type: string
Default: logs

Description: Name of the database that stores the logs. Macros cannot be used in database name. Also, when using an Oracle database, you cannot use the same database() settings in more than one destination.

dbd-option()
Type: string
Default: empty string

Description: Specify database options that are set whenever syslog-ng OSE connects to the database server. Consult the documentation of your database server for details on the available options. Syntax:

dbd-option(OPTION_NAME VALUE)

OPTION_NAME is always a string, VALUE is a string or a number. For example:

dbd-option("null.sleep.connect" 1)
dbd-option("null.sleep.query" 5)
disk-buffer()

Description: This option enables putting outgoing messages into the disk buffer of the destination to avoid message loss in case of a system failure on the destination side. It has the following options:

reliable()
Type: yes|no
Default: no

Description: If set to yes, syslog-ng OSE cannot lose logs in case of reload/restart, unreachable destination or syslog-ng OSE crash. This solution provides a slower, but reliable disk-buffer option. It is created and initialized at startup and gradually grows as new messages arrive. If set to no, the normal disk-buffer will be used. This provides a faster, but less reliable disk-buffer option.

Caution:

Hazard of data loss! If you change the value of reliable() option when there are messages in the disk-buffer, the messages stored in the disk-buffer will be lost.

dir()
Type: string
Default: N/A

Description: Defines the folder where the disk-buffer files are stored.

Caution:

When creating a new dir() option for a disk buffer, or modifying an existing one, make sure you delete the persist file.

syslog-ng OSE creates disk-buffer files based on the path recorded in the persist file. Therefore, if the persist file is not deleted after modifying the dir() option, then following a restart, syslog-ng OSE will look for or create disk-buffer files in their old location. To ensure that syslog-ng OSE uses the new dir() setting, the persist file must not contain any information about the destinations which the disk-buffer file in question belongs to.

disk-buf-size()
Type: number (bytes)
Default:

Description: This is a required option. The maximum size of the disk-buffer in bytes. The minimum value is 1048576 bytes. If you set a smaller value, the minimum value will be used automatically. It replaces the old log-disk-fifo-size() option.
mem-buf-length()
Type: number (messages)
Default: 10000
Description: Use this option if the option reliable() is set to no. This option contains the number of messages stored in overflow queue. It replaces the old log-fifo-size() option. It inherits the value of the global log-fifo-size() option if provided. If it is not provided, the default value is 10000 messages. Note that this option will be ignored if the option reliable() is set to yes.
mem-buf-size()
Type: number (bytes)
Default: 163840000
Description: Use this option if the option reliable() is set to yes. This option contains the size of the messages in bytes that is used in the memory part of the disk buffer. It replaces the old log-fifo-size() option. It does not inherit the value of the global log-fifo-size() option, even if it is provided. Note that this option will be ignored if the option reliable() is set to no.
qout-size()
Type: number (messages)
Default: 64
Description: The number of messages stored in the output buffer of the destination.

Options reliable() and disk-buf-size() are required options.

Example: Examples for using disk-buffer()

In the following case reliable disk-buffer() is used.

destination d_demo {
    network(
        "127.0.0.1"
        port(3333)
        disk-buffer(
            mem-buf-size(10000)
            disk-buf-size(2000000)
            reliable(yes)
            dir("/tmp/disk-buffer")
        )
    );
};

In the following case normal disk-buffer() is used.

destination d_demo {
    network(
        "127.0.0.1"
        port(3333)
           disk-buffer(
            mem-buf-length(10000)
            disk-buf-size(2000000)
            reliable(no)
            dir("/tmp/disk-buffer")
        )
    );
};
flags()
Type: list of flags
Default: empty string

Description: Flags related to the sql() destination.

  • dont-create-tables: Enable this flag to prevent syslog-ng OSE from creating non-existing database tables automatically. The syslog-ng OSE application typically has to create tables if you use macros in the table names. Available in syslog-ng OSE version 3.2 and later.

  • explicit-commits: By default, syslog-ng OSE commits every log message to the target database individually. When the explicit-commits option is enabled, messages are committed in batches. This improves the performance, but results in some latency, as the messages are not immediately sent to the database. The size and frequency of batched commits can be set using the flush-lines() and flush-timeout() parameters. The explicit-commits option is available in syslog-ng OSE version 3.2 and later.

Example: Setting flags for SQL destinations

The following example sets the dont-create-tables and explicit-commits flags for an sql() destination.

flags(dont-create-tables,explicit-commits)
flush-lines()
Type: number
Default: Use global setting.

Description: Specifies how many lines are flushed to a destination at a time. The syslog-ng OSE application waits for this number of lines to accumulate and sends them off in a single batch. Increasing this number increases throughput as more messages are sent in a single batch, but also increases message latency.

The syslog-ng OSE application flushes the messages if it has sent flush-lines() number of messages, or the queue became empty. If you stop or reload syslog-ng OSE or in case of network sources, the connection with the client is closed, syslog-ng OSE automatically sends the unsent messages to the destination.

For optimal performance when sending messages to an syslog-ng OSE server, make sure that the flush-lines() is smaller than the window size set using the log-iw-size() option in the source of your server.

flush-timeout() (DEPRECATED)
Type: time in milliseconds
Default: Use global setting.

Description: This is a deprecated option. Specifies the time syslog-ng waits for lines to accumulate in its output buffer. For details, see the flush-lines() option.

frac-digits()
Type: number
Default: 0

Description: The syslog-ng application can store fractions of a second in the timestamps according to the ISO8601 format. The frac-digits() parameter specifies the number of digits stored. The digits storing the fractions are padded by zeros if the original timestamp of the message specifies only seconds. Fractions can always be stored for the time the message was received. Note that syslog-ng can add the fractions to non-ISO8601 timestamps as well.

hook-commands()

Description: This option makes it possible to execute external programs when the relevant driver is initialized or torn down. The hook-commands() can be used with all source and destination drivers with the exception of the usertty() and internal() drivers.

NOTE: The syslog-ng OSE application must be able to start and restart the external program, and have the necessary permissions to do so. For example, if your host is running AppArmor or SELinux, you might have to modify your AppArmor or SELinux configuration to enable syslog-ng OSE to execute external applications.

Using the hook-commands() when syslog-ng OSE starts or stops

To execute an external program when syslog-ng OSE starts or stops, use the following options:

startup()
Type: string
Default: N/A

Description: Defines the external program that is executed as syslog-ng OSE starts.

shutdown()
Type: string
Default: N/A

Description: Defines the external program that is executed as syslog-ng OSE stops.

Using the hook-commands() when syslog-ng OSE reloads

To execute an external program when the syslog-ng OSE configuration is initiated or torn down, for example, on startup/shutdown or during a syslog-ng OSE reload, use the following options:

setup()
Type: string
Default: N/A

Description: Defines an external program that is executed when the syslog-ng OSE configuration is initiated, for example, on startup or during a syslog-ng OSE reload.

teardown()
Type: string
Default: N/A

Description: Defines an external program that is executed when the syslog-ng OSE configuration is stopped or torn down, for example, on shutdown or during a syslog-ng OSE reload.

Example: Using the hook-commands() with a network source

In the following example, the hook-commands() is used with the network() driver and it opens an iptables port automatically as syslog-ng OSE is started/stopped.

The assumption in this example is that the LOGCHAIN chain is part of a larger ruleset that routes traffic to it. Whenever the syslog-ng OSE created rule is there, packets can flow, otherwise the port is closed.

source {
   network(transport(udp)
	hook-commands(
          startup("iptables -I LOGCHAIN 1 -p udp --dport 514 -j ACCEPT")
          shutdown("iptables -D LOGCHAIN 1")
        )
     );
};
host()
Type: hostname or IP address
Default: n/a

Description: Hostname of the database server. Note that Oracle destinations do not use this parameter, but retrieve the hostname from the /etc/tnsnames.ora file.

NOTE:

If you specify host="localhost", syslog-ng will use a socket to connect to the local database server. Use host="127.0.0.1" to force TCP communication between syslog-ng and the local database server.

To specify the socket to use, set and export the MYSQL_UNIX_PORT environment variable, for example MYSQL_UNIX_PORT=/var/lib/mysql/mysql.sock; export MYSQL_UNIX_PORT.

indexes()
Type: string list
Default: "date", "facility", "host", "program"

Description: The list of columns that are indexed by the database to speed up searching. To disable indexing for the destination, include the empty indexes() parameter in the destination, simply omitting the indexes parameter will cause syslog-ng to request indexing on the default columns.

The syslog-ng OSE application will create the name of indexes automaticaly with the following method:

  • In case of MsSQL, PostgreSQL, MySQL or SQLite or (Oracle but tablename < 30 characters): {table}_{column}_idx.

  • In case of Oracle and tablename > 30 characters: md5sum of {table}_{column}-1 and the first character will be replaced by "i" character and the md5sum will be truncated to 30 characters.

local-time-zone()
Type: name of the timezone, or the timezone offset
Default: The local timezone.

Description: Sets the timezone used when expanding filename and tablename templates.

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.

log-fifo-size()
Type: number
Default: Use global setting.

Description: The number of messages that the output queue can store.

null()
Type: string
Default:

Description: If the content of a column matches the string specified in the null() parameter, the contents of the column will be replaced with an SQL NULL value. If unset (by default), the option does not match on any string. For details, see the Example: Using SQL NULL values.

Example: Using SQL NULL values

The null() parameter of the SQL driver can be used to replace the contents of a column with a special SQL NULL value. To replace every column that contains an empty string with NULL, use the null("") option, for example

destination d_sql {
    sql(type(pgsql)
    host("logserver") username("syslog-ng") password("password")
    database("logs")
    table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
    columns("datetime", "host", "program", "pid", "message")
    values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}")
    indexes("datetime", "host", "program", "pid", "message")
    null(""));
};

To replace only a specific column (for example pid) if it is empty, assign a default value to the column, and use this default value in the null() parameter:

destination d_sql {
    sql(type(pgsql)
    host("logserver") username("syslog-ng") password("password")
    database("logs")
    table("messages_${HOST}_${R_YEAR}${R_MONTH}${R_DAY}")
    columns("datetime", "host", "program", "pid", "message")
    values("${R_DATE}", "${HOST}", "${PROGRAM}", "${PID:-@@NULL@@}", "${MSGONLY}")
    indexes("datetime", "host", "program", "pid", "message")
    null("@@NULL@@"));
};

Ensure that the default value you use does not appear in the actual log messages, because other occurrences of this string will be replaced with NULL as well.

password()
Type: string
Default: n/a

Description: Password of the database user.

port()
Type: number
Default: 1433 TCP for MSSQL, 3306 TCP for MySQL, 1521 for Oracle, and 5432 TCP for PostgreSQL

Description: The port number to connect to.

retries()
Type: number (insertion attempts)
Default: 3

Description: The number of insertion attempts. If syslog-ng OSE could not insert a message into the database, it will repeat the attempt until the number of attempts reaches retries, then drops the connection to the database. For example, syslog-ng OSE will try to insert a message maximum three times by default (once for first insertion and twice if the first insertion was failed).

session-statements()
Type: comma-separated list of SQL statements
Default: empty string

Description: Specifies one or more SQL-like statement which is executed after syslog-ng OSE has successfully connected to the database. For example:

session-statements("SET COLLATION_CONNECTION='utf8_general_ci'")

Caution:

The syslog-ng OSE application does not validate or limit the contents of customized queries. Consequently, queries performed with a user with write-access can potentially modify or even harm the database. Use customized queries with care, and only for your own responsibility.

table()
Type: string
Default: messages

Description: Name of the database table to use (can include macros). When using macros, note that some databases limit the length of table names.

time-zone()
Type: name of the timezone, or the timezone offset
Default: unspecified

Description: Convert timestamps to the timezone specified by this option. If this option is not set, then the original timezone information in the message is used. Converting the timezone changes the values of all date-related macros derived from the timestamp, for example, HOUR. For the complete list of such macros, see Date-related macros.

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.

type()
Type: mssql, mysql, oracle, pgsql, or sqlite3
Default: mysql

Description: Specifies the type of the database, that is, the DBI database driver to use. Use the mssql option to send logs to an MSSQL database. For details, see the examples of the databases on the following sections.

username()
Type: string
Default: n/a

Description: Name of the database user.

values()
Type: string list
Default: "${R_YEAR}-${R_MONTH}-${R_DAY}, ${R_HOUR}:${R_MIN}:${R_SEC}", "${FACILITY}", "${LEVEL}", "${HOST}", "${PROGRAM}", "${PID}", "${MSGONLY}"

Description: The parts of the message to store in the fields specified in the columns() parameter.

It is possible to give a special value calling: default (without quotation marks).It means that the value will be used that is the default of the column type of this value.

Example: Value: default
columns("date datetime", "host varchar(32)", "row_id serial")
    values("${R_DATE}", "${HOST}", default)

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stomp: Publishing messages using STOMP

The stomp() driver sends messages to servers (message brokers) using the Simple (or Streaming) Text Oriented Message Protocol (STOMP), formerly known as TTMP. syslog-ng OSE supports version 1.0 of the STOMP protocol. The syslog-ng OSE stomp() driver supports persistence.

The name-value pairs selected with the value-pairs() option will be sent as STOMP headers, while the body of the STOMP message is empty by default (but you can add custom content using the body() option). Publishing the name-value pairs as headers makes it possible to use the Headers exchange-type and subscribe only to interesting log streams.

For the list of available parameters, see stomp() destination options.

Declaration:
stomp( host("<stomp-server-address>") );
Example: Using the stomp() driver

The following example shows the default values of the available options.

destination d_stomp {
    stomp(
        host("localhost")
        port(61613)
        destination("/topic/syslog")
        body("")             # optional, empty by default
        persistent(yes)
        ack(no)
        username("user")     # optional, empty by default
        password("password") # optional, empty by default
        value-pairs(scope(selected-macros, nv-pairs, sdata))
    );
};

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