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syslog-ng Premium Edition 7.0.18 - Administration Guide

Preface Introduction to syslog-ng The concepts of syslog-ng Installing syslog-ng The syslog-ng PE quick-start guide The syslog-ng PE configuration file Collecting log messages — sources and source drivers
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) office365: Fetching logs from Office 365 osquery: Collect and parse osquery result logs pipe: Collecting messages from named pipes 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 udp-balancer: Receiving UDP messages at very high rate unix-stream, unix-dgram: Collecting messages from UNIX domain sockets windowsevent: Collecting Windows event logs
Sending and storing log messages — destinations and destination drivers
elasticsearch2: Sending messages directly to Elasticsearch version 2.0 or higher (DEPRECATED) elasticsearch-http: Sending messages to Elasticsearch HTTP Event Collector file: Storing messages in plain-text files hdfs: Storing messages on the Hadoop Distributed File System (HDFS) http: Posting messages over HTTP kafka: Publishing messages to Apache Kafka logstore: Storing messages in encrypted files mongodb: Storing messages in a MongoDB database network: Sending messages to a remote log server using the RFC3164 protocol (network() driver) pipe: Sending messages to named pipes program: Sending messages to external applications python: writing custom Python destinations smtp: Generating SMTP messages (email) from logs splunk-hec: Sending messages to Splunk HTTP Event Collector sql: Storing messages in an SQL database stackdriver: Sending logs to the Google Stackdriver cloud 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) unix-stream, unix-dgram: Sending messages to UNIX domain sockets usertty: Sending messages to a user terminal — usertty() destination Client-side failover
Routing messages: log paths, flags, and filters Global options of syslog-ng PE TLS-encrypted message transfer Advanced Log Transfer Protocol Reliability and minimizing the loss of log messages Manipulating messages parser: Parse and segment structured messages Processing message content with a pattern database Correlating log messages Enriching log messages with external data Monitoring statistics and metrics of syslog-ng Multithreading and scaling in syslog-ng PE Troubleshooting syslog-ng Best practices and examples The syslog-ng manual pages Glossary

default-network-drivers: Receive and parse common syslog messages

The default-network-drivers() source is a special source that uses multiple source drivers to receive and parse several different types of syslog messages from the network. Available in version 7.0.9 and later.

To use the default-network-drivers() source, the scl.conf file must be included in your syslog-ng PE configuration:

@include "scl.conf"

Also, make sure that your SELinux, AppArmor, and firewall settings permit syslog-ng Premium Edition to access the ports where you want to receive messages, and that no other application is using these ports. By default, the default-network-drivers() source accepts messages on the following ports:

  • 514, both TCP and UDP, for RFC3164 (BSD-syslog) formatted traffic

  • 601 TCP, for RFC5424 (IETF-syslog) formatted traffic

  • 6514 TCP, for TLS-encrypted traffic

In addition to receiving messages on different ports and in different formats, this source tries to parse the messages automatically. If successful, it sets the ${.app.name} name-value pair to the name of the application that sent the log message. Currently it uses the following procedures.

Caution:

If you do not configure the TLS keys to dislay to the clients, syslog-ng PE cannot accept encrypted connections. The application starts and listens on TCP:6514, and can receive messages on other ports, but will display a warning messages about missing keys.

Parsing RFC3164-formatted messages

For RFC3164-formatted messages (that is, messages received on the ports set in options udp-port() and tcp-port() which default to port 514), syslog-ng PE attempts to use the following parsers. If a parser cannot parse the message, it passes the original message to the next parser.

  1. Parse the incoming raw message as a message from a Cisco device.

  2. Parse the incoming message as an RFC3164-formatted message.

    • If the incoming message was sent by a syslog-ng PE client using the syslog-ng() destination, parse its fields as a syslog-ng message.

      The Enterprise-wide message model or EWMM allows you to deliver structured messages from the initial receiving syslog-ng component right up to the central log server, through any number of hops. It does not matter if you parse the messages on the client, on a relay, or on the central server, their structured results will be available where you store the messages. Optionally, you can also forward the original raw message as the first syslog-ng component in your infrastructure has received it, which is important if you want to forward a message for example, to a SIEM system. To make use of the enterprise-wide message model, you have to use the syslog-ng() destination on the sender side, and the default-network-drivers() source on the receiver side.

    • Otherwise, apply the application adapters if the message was sent from an application that already has a specific parser in syslog-ng PE (for example, Splunk Common Information Model (CIM), iptables, or sudo).

Parsing RFC5424-formatted messages

For RFC5424-formatted messages (that is, messages received on the ports set in options rfc5424-tls-port() and rfc5424-tcp-port(), which default to port 6514 and 601), syslog-ng PE parses the message according to RFC5424, then attempts apply the application adapters if the message was sent from an application that already has a specific parser in syslog-ng PE (for example, Splunk Common Information Model (CIM), iptables, or sudo).

Example: Using the default-network-drivers() driver

The following example uses only the default settings.

source s_network {
    default-network-drivers();
};

The following example can receive TLS-encrypted connections on the default port (port 6514).

source s_network {
    default-network-drivers(
        tls(
            key-file("/path/to/ssl-private-key")
            cert-file("/path/to/ssl-cert")
		)
    );
};

default-network-drivers() source options

The systemd-journal() driver has the following options.

flags()
Type: assume-utf8, empty-lines, expect-hostname, guess-timezone, kernel, no-hostname, no-multi-line, no-parse, sanitize-utf8, store-legacy-msghdr, store-raw-message, syslog-protocol, validate-utf8
Default: empty set

Description: Specifies the log parsing options of the source.

  • assume-utf8: The assume-utf8 flag assumes that the incoming messages are UTF-8 encoded, but does not verify the encoding. If you explicitly want to validate the UTF-8 encoding of the incoming message, use the validate-utf8 flag.

  • empty-lines: Use the empty-lines flag to keep the empty lines of the messages. By default, syslog-ng PE removes empty lines automatically.

  • expect-hostname: If the expect-hostname flag is enabled, syslog-ng PE will assume that the log message contains a hostname and parse the message accordingly. This is the default behavior for TCP sources. Note that pipe sources use the no-hostname flag by default.

  • kernel: The kernel flag makes the source default to the LOG_KERN | LOG_NOTICE priority if not specified otherwise.

  • no-hostname: Enable the no-hostname flag if the log message does not include the hostname of the sender host. That way syslog-ng PE assumes that the first part of the message header is ${PROGRAM} instead of ${HOST}. For example:

    source s_dell {
        network(
            port(2000)
            flags(no-hostname)
        );
    };
  • no-multi-line: The no-multi-line flag disables line-breaking in the messages: the entire message is converted to a single line. Note that this happens only if the underlying transport method actually supports multi-line messages. Currently the file() and pipe() drivers support multi-line messages.

  • no-parse: By default, syslog-ng PE parses incoming messages as syslog messages. The no-parse flag completely disables syslog message parsing and processes the complete line as the message part of a syslog message. The syslog-ng PE application will generate a new syslog header (timestamp, host, and so on) automatically and put the entire incoming message into the MESSAGE part of the syslog message (available using the ${MESSAGE} macro). This flag is useful for parsing messages not complying to the syslog format.

    If you are using the flags(no-parse) option, then syslog message parsing is completely disabled, and the entire incoming message is treated as the ${MESSAGE} part of a syslog message. In this case, syslog-ng PE generates a new syslog header (timestamp, host, and so on) automatically. Note that since flags(no-parse) disables message parsing, it interferes with other flags, for example, disables flags(no-multi-line).

  • dont-store-legacy-msghdr: By default, syslog-ng stores the original incoming header of the log message. This is useful if the original format of a non-syslog-compliant message must be retained (syslog-ng automatically corrects minor header errors, for example, adds a whitespace before msg in the following message: Jan 22 10:06:11 host program:msg). If you do not want to store the original header of the message, enable the dont-store-legacy-msghdr flag.

  • sanitize-utf8: When using the sanitize-utf8 flag, syslog-ng PE converts non-UTF-8 input to an escaped form, which is valid UTF-8.

  • store-raw-message: Save the original message as received from the client in the ${RAWMSG} macro. You can forward this raw message in its original form to another syslog-ng node using the syslog-ng() destination, or to a SIEM system, ensuring that the SIEM can process it. Available only in 7.0.9 and later.

  • syslog-protocol: The syslog-protocol flag specifies that incoming messages are expected to be formatted according to the new IETF syslog protocol standard (RFC5424), but without the frame header. Note that this flag is not needed for the syslog driver, which handles only messages that have a frame header.

  • validate-utf8: The validate-utf8 flag enables encoding-verification for messages formatted according to the new IETF syslog standard (for details, see IETF-syslog messages). If theBOM1character is missing, but the message is otherwise UTF-8 compliant, syslog-ng automatically adds the BOM character to the message.

log-msg-size()
Type: number (bytes)
Default: Use the global log-msg-size() option, which defaults to 65536.

Description: Maximum length of a message in bytes. This length includes the entire message (the data structure and individual fields). The maximal value that can be set is 268435456 bytes (256MB). For messages using the IETF-syslog message format (RFC5424), the maximal size of the value of an SDATA field is 64kB.

In most cases, it is not recommended to set log-msg-size() higher than 10 MiB.

For details on how encoding affects the size of the message, see Message size and encoding.

Uses the value of the global option if not specified.

max-connections()
Type: number
Default: 10

Description: Specifies the maximum number of simultaneous connections.

Note that the total number of connections the default-network-drivers() source can use is 3*max-connections(), because this value applies to the network(tcp), syslog(tcp), and syslog(tls) connections individually.

rfc5424-tcp-port()
Type: number
Default:

601

Description: The TCP port number where the default-network-drivers() source receives RFC5424-formatted (IETF-syslog) messages.

rfc5424-tls-port()
Type: number
Default:

6514

Description: The TCP port number where the default-network-drivers() source receives RFC5424-formatted (IETF-syslog), TLS-encrypted messages.

Caution:

To receive messages using a TLS-encrypted connection, you must set the tls(key-file() cert-file()) options of the default-network-drivers() source. For example:

source s_network {
    default-network-drivers(
        tls(
            key-file("/path/to/ssl-private-key")
            cert-file("/path/to/ssl-cert")
        )
    );
};
tcp-port()
Type: number
Default:

514

Description: The TCP port number where the default-network-drivers() source receives RFC3164-formatted (BSD-syslog) messages.

tls()
Type: tls options
Default: n/a

Description: This option sets various options related to TLS encryption, for example, key/certificate files and trusted CA locations. TLS can be used only with tcp-based transport protocols. For details, see TLS options.

udp-port()
Type: number
Default:

514

Description: The UDP port number where the default-network-drivers() source receives RFC3164-formatted (BSD-syslog) messages.

internal: Collecting internal messages

All messages generated internally by syslog-ng use this special source. To collect warnings, errors and notices from syslog-ng itself, include this source in one of your source statements.

internal()

The syslog-ng application will issue a warning upon startup if none of the defined log paths reference this driver.

Example: Using the internal() driver
source s_local { internal(); };
The syslog-ng PE application sends the following message types from the internal() source
  • fatal: Priority value: critical (2), Facility value: syslog (5)

  • error: Priority value: error (3), Facility value: syslog (5)

  • warning: Priority value: warning (4), Facility value: syslog (5)

  • notice: Priority value: notice (5), Facility value: syslog (5)

  • info: Priority value: info (6), Facility value: syslog (5)

internal() source options

The internal() driver has the following options:

host-override()
Type: string
Default:

Description: Replaces the ${HOST} part of the message with the parameter string.

log-iw-size()
Type: number
Default: 100

Description: The size of the initial window, this value is used during flow control. For details on flow control, see Managing incoming and outgoing messages with flow-control.

normalize-hostnames()
Accepted values: yes | no
Default: no

Description: If enabled (normalize-hostnames(yes)), syslog-ng PE converts the hostnames to lowercase.

program-override()
Type: string
Default:

Description: Replaces the ${PROGRAM} part of the message with the parameter string. For example, to mark every message coming from the kernel, include the program-override("kernel") option in the source containing /proc/kmsg.

tags()
Type: string
Default:

Description: Label the messages received from the source with custom tags. Tags must be unique, and enclosed between double quotes. When adding multiple tags, separate them with comma, for example, tags("dmz", "router"). This option is available only in syslog-ng 3.1 and later.

use-fqdn()
Type: yes or no
Default: no

Description: Add Fully Qualified Domain Name instead of short hostname. This option can be specified globally, and per-source as well. The local setting of the source overrides the global option if available.

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