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syslog-ng Premium Edition 7.0.14 - 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) 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 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 (e-mail) 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

Collecting log messages — sources and source drivers

How sources work

A source is where syslog-ng receives log messages. Sources consist of one or more drivers, each defining where and how messages are received.

To define a source, add a source statement to the syslog-ng configuration file using the following syntax:

source <identifier> {
    source-driver(params);
    source-driver(params);
    ...
};

Example: A simple source statement

The following source statement receives messages on the TCP port 1999 of the interface having the 10.1.2.3 IP address.

source s_demo_tcp {
    network(
        ip(10.1.2.3)
        port(1999)
    );
};
Example: A source statement using two source drivers

The following source statement receives messages on the 1999 TCP port and the 1999 UDP port of the interface having the 10.1.2.3 IP address.

source s_demo_two_drivers {
    network(
        ip(10.1.2.3)
        port(1999)
    );
    network(
        ip(10.1.2.3)
        port(1999)
        transport("udp")
    );
};
Example: Setting default priority and facility

If the message received by the source does not have a proper syslog header, you can use the default-facility() and default-priority() options to set the facility and priority of the messages. Note that these values are applied only to messages that do not set these parameters in their header.

source headerless_messages {
    network(
        default-facility(syslog)
        default-priority(emerg)
    );
};

Define a source only once. The same source can be used in several log paths. Duplicating sources causes syslog-ng to open the source (TCP/IP port, file, and so on) more than once, which might cause problems. For example, include the /dev/log file source only in one source statement, and use this statement in more than one log path if needed.

Caution:

Sources and destinations are initialized only when they are used in a log statement. For example, syslog-ng PE starts listening on a port or starts polling a file only if the source is used in a log statement. For details on creating log statements, see Routing messages: log paths, flags, and filters.

To collect log messages on a specific platform, it is important to know how the native syslogd communicates on that platform. The following table summarizes the operation methods of syslogd on some of the tested platforms:

Table 8: Communication methods used between the applications and syslogd
Platform Method
Linux A SOCK_DGRAM unix socket named /dev/log. Newer distributions that use systemd collect log messages into a journal file.
BSD flavors A SOCK_DGRAM unix socket named /var/run/log.
Solaris (2.5 or below) An SVR4 style STREAMS device named /dev/log.
Solaris (2.6 or above) In addition to the STREAMS device used in earlier versions, 2.6 uses a new multithreaded IPC method called door. By default the door used by syslogd is /etc/.syslog_door.
HP-UX 11 or later HP-UX uses a named pipe called /dev/log that is padded to 2048 bytes, for example source s_hp-ux {pipe ("/dev/log" pad-size(2048)}.
AIX 5.2 and 5.3 A SOCK_STREAM or SOCK_DGRAM unix socket called /dev/log.

Each possible communication mechanism has a corresponding source driver in syslog-ng. For example, to open a unix socket with SOCK_DGRAM style communication use the driver unix-dgram. The same socket using the SOCK_STREAM style — as used under Linux — is called unix-stream.

Example: Source statement on a Linux based operating system

The following source statement collects the following log messages:

  • internal(): Messages generated by syslog-ng.

  • network(transport("udp")): Messages arriving to the 514/UDP port of any interface of the host.

  • unix-dgram("/dev/log");: Messages arriving to the /dev/log socket.

source s_demo {
    internal();
    network(transport("udp"));
    unix-dgram("/dev/log");
};

The following table lists the source drivers available in syslog-ng.

Table 9: Source drivers available in syslog-ng
Name Description
file() Opens the specified file and reads messages.
internal() Messages generated internally in syslog-ng.
linux-audit() Reads the logfiles of the auditd application.
network() Receives messages from remote hosts using the BSD-syslog protocol over IPv4 and IPv6. Supports the TCP, UDP, ALTP, and TLS network protocols.
pipe() Opens the specified named pipe and reads messages.
program() Opens the specified application and reads messages from its standard output.
python() and python-fetcher() Receive or fetch messages using a custom source written in Python.
sun-stream(), sun-streams() Opens the specified STREAMS device on Solaris systems and reads incoming messages.
syslog() Listens for incoming messages using the new IETF-standard syslog protocol.
system() Automatically detects which platform syslog-ng PE is running on, and collects the native log messages of that platform.
systemd-journal() Collects messages directly from the journal of platforms that use systemd.
systemd-syslog() Collects messages from the journal using a socket on platforms that use systemd.
unix-dgram() Opens the specified unix socket in SOCK_DGRAM mode and listens for incoming messages.
unix-stream() Opens the specified unix socket in SOCK_STREAM mode and listens for incoming messages.
windowsevent() Reads messages from the Windows Event Collector tool.

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.

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.

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