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syslog-ng Open Source Edition 3.22 - 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, using the librdkafka client) 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() 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 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: 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

Elasticsearch2 destination options (DEPRECATED)

 Caution:

This destination is deprecated and will be removed from a future version of syslog-ng OSE. We recommend using the elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API destination instead.

The elasticsearch2 destination can directly send log messages to Elasticsearch, allowing you to search and analyze your data in real time, and visualize it with Kibana. The elasticsearch2 destination has the following options.

Required options:

The following options are required: index(), type(). In node mode, either the cluster() or the resource() option is required as well. Note that to use elasticsearch2, you must add the following lines to the beginning of your syslog-ng OSE configuration:

@module mod-java
@include "scl.conf"
client-lib-dir()
Type: string
Default: The syslog-ng OSE module directory: /opt/syslog-ng/lib/syslog-ng/java-modules/

Description: The list of the paths where the required Java classes are located. For example, class-path("/opt/syslog-ng/lib/syslog-ng/java-modules/:/opt/my-java-libraries/libs/"). If you set this option multiple times in your syslog-ng OSE configuration (for example, because you have multiple Java-based destinations), syslog-ng OSE will merge every available paths to a single list.

Description: Include the path to the directory where you copied the required libraries (see Prerequisites), for example, client-lib-dir(/user/share/elasticsearch-2.2.0/lib).

client-mode()
Type: http | https | transport | node | searchguard
Default: node

Description: Specifies the client mode used to connect to the Elasticsearch server, for example, client-mode("node").

  • HTTP mode

    The syslog-ng OSE application sends messages over HTTP using the REST API of Elasticsearch, and uses the cluster-url() and cluster() options from the syslog-ng OSE configuration file. In HTTP mode, syslog-ng OSE elasticsearch2 driver can send log messages to every Elasticsearch version, including 1.x-6.x. Note that HTTP mode is available in syslog-ng OSE version 3.8 and newer.

    In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE does not have any direct influence on it.

  • HTTPS mode

    The syslog-ng OSE application sends messages over an encrypted and optionally authenticated HTTPS channel using the REST API of Elasticsearch, and uses the cluster-url() and cluster() options from the syslog-ng OSE configuration file. In HTTPS mode, syslog-ng OSE elasticsearch2 driver can send log messages to every Elasticsearch version, including 1.x-6.x. Note that HTTPS mode is available in syslog-ng OSE version 3.10 and newer.

    This mode supports password-based and certificate-based authentication of the client, and can verify the certificate of the server as well.

    In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE does not have any direct influence on it.

  • Transport mode

    The syslog-ng OSE application uses the transport client API of Elasticsearch, and uses the server(), port(), and cluster() options from the syslog-ng OSE configuration file.

  • Node mode

    The syslog-ng OSE application acts as an Elasticsearch node (client no-data), using the node client API of Elasticsearch. Further options for the node can be describe in an Elasticsearch configuration file specified in the resource() option.

    		 NOTE:

    In Node mode, it is required to define the home of the elasticsearch installation with the path.home parameter in the .yml file. For example: path.home: /usr/share/elasticsearch.

  • Search Guard mode

    Use the Search Guard Elasticsearch plugin to encrypt and authenticate your connections from syslog-ng OSE to Elasticsearch 2.x. For Elasticsearch versions 5.x and newer, use HTTPS mode. For details on configuring Search Guard mode, see Search Guard and syslog-ng OSE.

cluster()
Type: string
Default: N/A

Description: Specifies the name or the Elasticsearch cluster, for example, cluster("my-elasticsearch-cluster"). Optionally, you can specify the name of the cluster in the Elasticsearch resource file. For details, see resource().

cluster-url()
Type: string
Default: N/A

Description: Specifies the URL or the Elasticsearch cluster, for example, cluster-url("http://192.168.10.10:9200")"). Note that this option works only in HTTP mode: client-mode(http)

In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE does not have any direct influence on it.

For example:

destination d_elasticsearch {
  elasticsearch2(
    client-lib-dir("/usr/share/elasticsearch/lib/")
    index("syslog-${YEAR}.${MONTH}.${DAY}")
    type("syslog")
    time-zone("UTC")
    client-mode("http")
    cluster-url("http://node01:9200 http://node02:9200")
  );
};
concurrent-requests()
Type: number
Default: 0

Description: The number of concurrent (simultaneous) requests that syslog-ng OSE sends to the Elasticsearch server. Set this option to 1 or higher to increase performance. When using the concurrent-requests() option, make sure that the flush-limit() option is higher than one, otherwise it will not have any noticeable effect. For details, see flush-limit().

 Caution:

Hazard of data loss! Using the concurrent-requests() option increases the number of messages lost in case the Elasticsearch server becomes unaccessible.

custom-id()
Type: template or template function
Default: N/A

Description: Use this option to specify a custom ID for the records inserted into Elasticsearch. If this option is not set, the Elasticsearch server automatically generates and ID for the message. For example: custom-id(${UNIQID}) (Note that to use the ${UNIQID} macro, the use-uniqid() global option must be enabled. For details, see use-uniqid().)

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. Note that if you change the value of this option and the disk-buffer already exists, the change will take effect when the disk-buffer becomes empty.

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")
        )
    );
};
flush-limit()
Type: number
Default: 5000

Description: The number of messages that syslog-ng OSE sends to the Elasticsearch server in a single batch.

  • If flush-limit is set to 1: syslog-ng OSE sends the message reliably: it sends a message to Elasticsearch, then waits for a reply from Elasticsearch. In case of failure, syslog-ng OSE repeats sending the message, as set in the retries() parameter. If sending the message fails for retries() times, syslog-ng OSE drops the message.

    This method ensures reliable message transfer, but is slow (about 1000 messages/second).

  • If flush-limit is higher than 1: syslog-ng OSE sends messages in a batch, and receives the response asynchronously. In case of a problem, syslog-ng OSE cannot resend the messages.

    This method is relatively fast (depending on the size of flush-limit, about 8000 messages/second), but the transfer is not reliable. In transport mode, over 5000-30000 messages can be lost before syslog-ng OSE recognizes the error. In node mode, about 1000 messages can be lost.

  • If concurrent-requests is higher than 1, syslog-ng OSE can send multiple batches simultaneously, increasing performance (and also the number of messages that can be lost in case of an error).

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")
        )
     );
};
http-auth-type()
Type: none | basic | clientcert
Default: none

Description: Determines how syslog-ng OSE authenticates to the Elasticsearch server. Depending on the value of this option, you might have to set other options as well. Possible values:

This option is used only in HTTPS mode: client-mode("https"), and is available in syslog-ng OSE version 3.10 and newer.

Example: HTTPS authentication examples

The following simple examples show the different authentication modes.

Simple password authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("basic")
        http-auth-type-basic-username("example-username")
        http-auth-type-basic-password("example-password")
    );
};

Certificate authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server without authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("none")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng OSE client and the Elasticsearch server):

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-truststore-password("password-to-your-keystore")
    );
};
http-auth-type-basic-password()
Type: string
Default: N/A

Description: The password to use for password-authentication on the Elasticsearch server. You must also set the http-auth-type-basic-username option.

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("basic"), and is available in syslog-ng OSE version 3.10 and newer.

Simple password authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("basic")
        http-auth-type-basic-username("example-username")
        http-auth-type-basic-password("example-password")
    );
};
http-auth-type-basic-username()
Type: string
Default: N/A

Description: The username to use for password-authentication on the Elasticsearch server. You must also set the http-auth-type-basic-password option.

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("basic"), and is available in syslog-ng OSE version 3.10 and newer.

Simple password authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("basic")
        http-auth-type-basic-username("example-username")
        http-auth-type-basic-password("example-password")
    );
};
index()
Type: string
Default: N/A

Description: Name of the Elasticsearch index to store the log messages. You can use macros and templates as well.

java-keystore-filepath()
Type: string
Default: N/A

Description: Path to the Java keystore file that stores the certificate that syslog-ng OSE uses to authenticate on the Elasticsearch server. You must also set the java-keystore-password option.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("clientcert"), and is available in syslog-ng OSE version 3.10 and newer.

Certificate authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng OSE client and the Elasticsearch server):

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-truststore-password("password-to-your-keystore")
    );
};
java-keystore-password()
Type: string
Default: N/A

Description: The password of the Java keystore file set in the java-keystore-filepath option.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode with basic authentication: client-mode("https") and http-auth-type("clientcert"), and is available in syslog-ng OSE version 3.10 and newer.

Certificate authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("<path-to-your-java-keystore>.jks")
        java-keystore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng OSE client and the Elasticsearch server):

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-truststore-password("password-to-your-keystore")
    );
};
java-truststore-filepath()
Type: string
Default: N/A

Description: Path to the Java keystore file that stores the CA certificate that syslog-ng OSE uses to verify the certificate of the Elasticsearch server. You must also set the java-truststore-password option.

If you do not set the java-truststore-filepath option, syslog-ng OSE does accepts any certificate that the Elasticsearch server shows. In this case, the identity of the server is not verified, only the connection is encrypted.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode: client-mode("https"), and is available in syslog-ng OSE version 3.10 and newer.

Verify the certificate of the Elasticsearch server without authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("none")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng OSE client and the Elasticsearch server):

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-truststore-password("password-to-your-keystore")
    );
};
java-truststore-password()
Type: string
Default: N/A

Description: The password of the Java truststore file set in the java-truststore-filepath option.

To import a certificate into a Java keystore, use the appropriate tool of your Java implementation. For example, on Oracle Java, you can use the keytool utility:

keytool -import -alias ca -file <certificate-to-import> -keystore <keystore-to-import> -storepass <password-to-the-keystore>

This option is used only in HTTPS mode: client-mode("https"), and is available in syslog-ng OSE version 3.10 and newer.

Verify the certificate of the Elasticsearch server without authentication:

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("none")
        java-truststore-filepath("<path-to-your-java-keystore>.jks")
        java-truststore-password("password-to-your-keystore")
    );
};

Verify the certificate of the Elasticsearch server and perform certificate authentication (this is actually a mutual, certificate-based authentication between the syslog-ng OSE client and the Elasticsearch server):

destination d_elastic {
    elasticsearch2(
        client-mode("https")
        cluster("es-syslog-ng")
        index("x201")
        cluster-url("http://192.168.33.10:9200")
        type("slng_test_type")
        flush-limit("0")
        http-auth-type("clientcert")
        java-keystore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-keystore-password("password-to-your-keystore")
        java-truststore-filepath("&amp;lt;path-to-your-java-keystore&amp;gt;.jks")
        java-truststore-password("password-to-your-keystore")
    );
};
jvm-options()
Type: list
Default: N/A

Description: Specify the Java Virtual Machine (JVM) settings of your Java destination from the syslog-ng OSE configuration file.

For example:

jvm-options("-Xss1M -XX:+TraceClassLoading")

You can set this option only as a global option, by adding it to the options statement of the syslog-ng configuration file.

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

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

on-error()
Accepted values:

drop-message|drop-property|fallback-to-string|

silently-drop-message|silently-drop-property|silently-fallback-to-string

Default: Use the global setting (which defaults to drop-message)

Description: Controls what happens when type-casting fails and syslog-ng OSE cannot convert some data to the specified type. By default, syslog-ng OSE drops the entire message and logs the error. Currently the value-pairs() option uses the settings of on-error().

  • drop-message: Drop the entire message and log an error message to the internal() source. This is the default behavior of syslog-ng OSE.

  • drop-property: Omit the affected property (macro, template, or message-field) from the log message and log an error message to the internal() source.

  • fallback-to-string: Convert the property to string and log an error message to the internal() source.

  • silently-drop-message: Drop the entire message silently, without logging the error.

  • silently-drop-property: Omit the affected property (macro, template, or message-field) silently, without logging the error.

  • silently-fallback-to-string: Convert the property to string silently, without logging the error.

port()
Type: number
Default: 9300

Description: The port number of the Elasticsearch server. This option is used only in transport mode: client-mode("transport")

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

Description: The number of times syslog-ng OSE attempts to send a message to this destination. If syslog-ng OSE could not send a message, it will try again until the number of attempts reaches retries, then drops the message.

resource()
Type: string
Default: N/A

Description: The list of Elasticsearch resources to load, separated by semicolons. For example, resource("/home/user/elasticsearch/elasticsearch.yml;/home/user/elasticsearch/elasticsearch2.yml").

server()
Type: list of hostnames
Default: 127.0.0.1

Description: Specifies the hostname or IP address of the Elasticsearch server. When specifying an IP address, IPv4 (for example, 192.168.0.1) or IPv6 (for example, [::1]) can be used as well. When specifying multiple addresses, use space to separate the addresses, for example, server("127.0.0.1 remote-server-hostname1 remote-server-hostname2")

This option is used only in transport mode: client-mode("transport")

In version 3.10 and newer, you can list multiple servers in HTTP and HTTPS mode in the cluster-url() and server() options. The syslog-ng OSE application will use these destination servers in load-balancing fashion. Note that load-balancing is handled by an external library (Jest), syslog-ng OSE does not have any direct influence on it.

For example:

destination d_elasticsearch {
  elasticsearch2(
    client-lib-dir("/usr/share/elasticsearch/lib/")
    index("syslog-${YEAR}.${MONTH}.${DAY}")
    type("syslog")
    time-zone("UTC")
    client-mode("http")
    server("node01 node02")
    port(9200)
  );
};
skip-cluster-health-check()
Type: yes|no
Default: no

Description: By default, when connecting to an Elasticsearch cluster, syslog-ng OSE checks the state of the cluster. If the primary shards of the cluster are not active, syslog-ng OSE will not send messages, but wait for them to become active. To disable this health check and send the messages to Elasticsearch anyway, use the skip-cluster-health-check(yes) option in your configuration.

template()
Type: template or template function
Default: $(format-json --scope rfc5424 --exclude DATE --key ISODATE @timestamp=${ISODATE})

Description: The message as sent to the Elasticsearch server. Typically, you will want to use the command-line notation of the format-json template function.

To add a @timestamp field to the message, for example, to use with Kibana, include the @timestamp=${ISODATE} expression in the template. For example: template($(format-json --scope rfc5424 --exclude DATE --key ISODATE @timestamp=${ISODATE}))

For details on formatting messages in JSON format, see format-json.

throttle()
Type: number
Default: 0

Description: Sets the maximum number of messages sent to the destination per second. Use this output-rate-limiting functionality only when using disk-buffer as well to avoid the risk of losing messages. Specifying 0 or a lower value sets the output limit to unlimited.

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.

Version 3.10 and newer of syslog-ng OSE automatically converts the timestamp (date) of the message to UTC, as needed by Elasticsearch and Kibana.

ts-format()
Type: rfc3164, bsd, rfc3339, iso
Default: rfc3164

Description: Override the global timestamp format (set in the global ts-format() parameter) for the specific destination. For details, see ts-format().

 NOTE:

This option applies only to file and file-like destinations. Destinations that use specific protocols (for example, network(), or syslog()) ignore this option. For protocol-like destinations, use a template locally in the destination, or use the proto-template option.

type()
Type: string
Default: N/A

Description: The type of the index. For example, type("test").

Example use cases of sending logs to Elasticsearch using syslog-ng

This section aims to give you some practical examples about how to make the most of your Elasticsearch-based logging using syslog-ng. Read the following blog posts to learn how to:

elasticsearch-http: Sending messages to Elasticsearch HTTP Bulk API

Version 3.21 of syslog-ng OSE can directly post log messages to an Elasticsearch deployment using the Elasticsearch Bulk API over the HTTP and Secure HTTP (HTTPS) protocols.

HTTPS connection, as well as password- and certificate-based authentication is supported. The content of the events is sent in JSON format.

Declaration:
d_elasticsearch_http {
    elasticsearch-http(
        index("<elasticsearch-index-to-store-messages>")
        url("https://your-elasticsearch-server1:9200/_bulk" "https://your-elasticsearch-server2:9200/_bulk")
        type("<type-of-the-index>")
    );
};

Use an empty string to omit the type from the index: type(""). For example, you need to do that when using Elasticsearch 7 or newer, and you use a mapping in Elasticsearch to modify the type of the data.

The driver automatically uses the proxy settings of the host, there is no option to set it in the syslog-ng OSE configuration. Specifically, the driver uses the settings of the http_proxy and https_proxy environment variables.

Example: Sending log data to Elasticsearch

The following example defines a elasticsearch-http() destination, with only the required options.

destination d_elasticsearch_http {
    elasticsearch-http(
        index("<name-of-the-index>")
        type("<type-of-the-index>")
        url("http://my-elastic-server:9200/_bulk")
    );
};


log {
    source(s_file);
    destination(d_elasticsearch_http);
    flags(flow-control);
};

The following example uses mutually-authenticated HTTPS connection, templated index, and also sets the type() and some other options.

destination d_elasticsearch_https {
    elasticsearch-http(
        url("https://node01.example.com:9200/_bulk")
        index("test-${YEAR}${MONTH}${DAY}")
        time-zone("UTC")
        type("test")
        workers(4)
        batch-lines(16)
        timeout(10)
        tls(
            ca-file("ca.pem")
            cert-file("syslog_ng.crt.pem")
            key-file("syslog_ng.key.pem")
            peer-verify(yes)
        )
    );
};

This driver is actually a reusable configuration snippet configured to send log messages using the tcp() driver using a template. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of this configuration snippet on GitHub.

Batch mode and load balancing

The elasticsearch-http() destination automatically sends multiple log messages in a single HTTP request, increasing the rate of messages that your Elasticsearch deployment can consume. For details on adjusting and fine-tuning the batch mode of the elasticsearch-http() destination, see the following section.

Batch size

The batch-lines(), batch-lines(), and batch-timeout() options of the destination determine how many log messages syslog-ng OSE sends in a batch. The batch-lines() option determines the maximum number of messages syslog-ng OSE puts in a batch in. This can be limited based on size and time:

  • syslog-ng OSE sends a batch every batch-timeout() milliseconds, even if the number of messages in the batch is less than batch-lines(). That way the destination receives every message in a timely manner even if suddenly there are no more messages.

  • syslog-ng OSE sends the batch if the total size of the messages in the batch reaches batch-bytes() bytes.

To increase the performance of the destination, increase the number of worker threads for the destination using the workers() option, or adjust the batch-bytes(), batch-lines(), batch-timeout() options.

Example: HTTP batch mode

In the following example, a batch consists of 100 messages, or a maximum of 512 kilobytes, and is sent every 20 seconds (20000 milliseconds).

destination d_elasticsearch-http {
    elasticsearch-http(url("http://your-elasticsearch-server:9200/_bulk")
        index("<elasticsearch-index-to-store-messages>")
        type("")
        url("http://your-elasticsearch-server:9200/_bulk")
        batch-lines(100)
        batch-bytes(512Kb)
        batch-timeout(10000)
    );
};
Load balancing between multiple Elasticsearch indexers

Starting with version 3.19, you can specify multiple URLs, for example, url("site1", "site2"). In this case, syslog-ng OSE sends log messages to the specified URLs in a load-balance fashion. This means that syslog-ng OSE sends each message to only one URL. For example, you can use this to send the messages to a set of ingestion nodes or indexers of your SIEM solution if a single node cannot handle the load. Note that the order of the messages as they arrive on the servers can differ from the order syslog-ng OSE has received them, so use load-balancing only if your server can use the timestamp from the messages. If the server uses the timestamp when it receives the messages, the order of the messages will be incorrect.

 Caution:

If you set multiple URLs in the url() option, set the persist-name() option as well to avoid data loss.

Starting with version syslog-ng OSE version 3.22, you can use any of the following formats to specify multiple URLs:

url("server1", "server2", "server3"); # comma-separated strings
url("server1" "server2" "server3"); # space-separated strings
url("server1 server2 server3"); # space-separated within a single string
url("server1,server2,server3"); # comma-separated within a single string
Example: HTTP load balancing

The following destination sends log messages to 3 different Elasticsearch indexer nodes. Each node is assigned a separate worker thread. A batch consists of 100 messages, or a maximum of 512 kilobytes, and is sent every 20 seconds (20000 milliseconds).

destination d_elasticsearch-http {
    elasticsearch-http(url("http://your-elasticsearch-server1:9200/_bulk" "http://your-elasticsearch-server2:9200/_bulk" "http://your-elasticsearch-server3:9200/_bulk")
        batch-lines(100)
        batch-bytes(512Kb)
        batch-timeout(20000)
        persist-name("d_elasticsearch-http-load-balance")
    );
};

If you are using load-balancing (that is, you have configured multiple servers in the url() option), increase the number of worker threads at least to the number of servers. For example, if you have set three URLs (url("site1", "site2", "site3")), set the workers() option to 3 or more.

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