syslog-ng Open Source Edition 3.16 - Administration Guide

Options of syslog-parser parsers

The syslog-parser has the following options.

default-facility()

Description: This parameter assigns a facility value to the messages received from the file source if the message does not specify one.

default-priority()

Description: This parameter assigns an emergency level to the messages received from the file source if the message does not specify one. For example, default-priority(warning).

flags()

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 OSE removes empty lines automatically.

• expect-hostname: If the expect-hostname flag is enabled, syslog-ng OSE 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 OSE 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 OSE 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 OSE 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 OSE 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 OSE 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 3.16 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.

template()

Description: The macro that contains the part of the message that the parser will process. It can also be a macro created by a previous parser of the log path. By default, the parser processes the entire message (${MESSAGE}).

Parsing messages with comma-separated and similar values

The syslog-ng OSE application can separate parts of log messages (that is, the contents of the ${MESSAGE} macro) at delimiter characters or strings to named fields (columns). One way to achieve this is to use a csv (comma-separated-values) parser (for other methods and possibilities, see the other sections of parser: Parse and segment structured messages. The parsed fields act as user-defined macros that can be referenced in message templates, file- and tablenames, and so on.

Parsers are similar to filters: they must be defined in the syslog-ng OSE configuration file and used in the log statement. You can also define the parser inline in the log path.

To create a csv-parser(), you have to define the columns of the message, the separator characters or strings (also called delimiters, for example, semicolon or tabulator), and optionally the characters that are used to escape the delimiter characters (quote-pairs()).

parser <parser_name> {
    csv-parser(
        columns(column1, column2, ...)
        delimiters(chars("<delimiter_characters>"), strings("<delimiter_strings>"))
    );
};

Column names work like macros.

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

parser p_hostname_segmentation {
    csv-parser(columns("HOSTNAME.NAME", "HOSTNAME.ID")
    delimiters("-")
    flags(escape-none)
    template("${HOST}"));
};
destination d_file {
    file("/var/log/messages-${HOSTNAME.NAME:-examplehost}");
};
log {
    source(s_local);
    parser(p_hostname_segmentation);
    destination(d_file);
};

"%h %l %u %t \"%r\" %>s %b \"%{Referer}i\" \"%{User-Agent}i\" %T %v"

192.168.1.1 - - [31/Dec/2007:00:17:10 +0100] "GET /cgi-bin/example.cgi HTTP/1.1" 200 2708 "-" "curl/7.15.5 (i4 86-pc-linux-gnu) libcurl/7.15.5 OpenSSL/0.9.8c zlib/1.2.3 libidn/0.6.5" 2 example.mycompany

parser p_apache {
    csv-parser(
        columns("APACHE.CLIENT_IP", "APACHE.IDENT_NAME", "APACHE.USER_NAME",
        "APACHE.TIMESTAMP", "APACHE.REQUEST_URL", "APACHE.REQUEST_STATUS",
        "APACHE.CONTENT_LENGTH", "APACHE.REFERER", "APACHE.USER_AGENT",
        "APACHE.PROCESS_TIME", "APACHE.SERVER_NAME")
        flags(escape-double-char,strip-whitespace)
        delimiters(" ")
        quote-pairs('""[]')
    );
};

log {
    source(s_local);
    parser(p_apache);
    destination(d_file);
};
destination d_file {
    file("/var/log/messages-${APACHE.USER_NAME:-nouser}");
};

parser p_apache_timestamp {
    csv-parser(
        columns("APACHE.TIMESTAMP.DAY", "APACHE.TIMESTAMP.MONTH", "APACHE.TIMESTAMP.YEAR", "APACHE.TIMESTAMP.HOUR", "APACHE.TIMESTAMP.MIN", "APACHE.TIMESTAMP.MIN", "APACHE.TIMESTAMP.ZONE")
        delimiters("/: ")
        flags(escape-none)
        template("${APACHE.TIMESTAMP}")
    );
};
log {
    source(s_local);
    parser(p_apache);
    parser(p_apache_timestamp);
    destination(d_file);
};

Options of CSV parsers

The syslog-ng OSE application can separate parts of log messages (that is, the contents of the ${MESSAGE} macro) at delimiter characters or strings to named fields (columns). One way to achieve this is to use a csv (comma-separated-values) parser (for other methods and possibilities, see the other sections of parser: Parse and segment structured messages. The parsed fields act as user-defined macros that can be referenced in message templates, file- and tablenames, and so on.

Parsers are similar to filters: they must be defined in the syslog-ng OSE configuration file and used in the log statement. You can also define the parser inline in the log path.

To create a csv-parser(), you have to define the columns of the message, the separator characters or strings (also called delimiters, for example, semicolon or tabulator), and optionally the characters that are used to escape the delimiter characters (quote-pairs()).

parser <parser_name> {
    csv-parser(
        columns(column1, column2, ...)
        delimiters(chars("<delimiter_characters>"), strings("<delimiter_strings>"))
    );
};

Column names work like macros.

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

parser p_demo_parser {
    csv-parsercsv-parser(
        prefix(".csv.")
        delimiters(" ")
        dialect(escape-backslash)
        flags(strip-whitespace, greedy)
        columns("column1", "column2", "column3")
    );
};

prefix()

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

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

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

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

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

Parsing key=value pairs

The syslog-ng OSE application can separate a message consisting of whitespace or comma-separated key=value pairs (for example, Postfix log messages) into name-value pairs. You can also specify other separator character instead of the equal sign, for example, colon (:) to parse MySQL log messages. The syslog-ng OSE application automatically trims any leading or trailing whitespace characters from the keys and values, and also parses values that contain unquoted whitespace. For details on using value-pairs in syslog-ng OSE see Structuring macros, metadata, and other value-pairs.

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

To parse key=value pairs, define a parser that has the kv-parser() option. Defining the prefix is optional. By default, the parser will process the ${MESSAGE} part of the log message. You can also define the parser inline in the log path.

Declaration:

parser parser_name {
    kv-parser(
        prefix()
    );
};

Jun 20 12:05:12 mail.example.com <info> postfix/qmgr[35789]: EC2AC1947DA: from=<me@example.com>, size=807, nrcpt=1 (queue active)

source s_kv {
    network(port(21514));
};

destination d_json {
    file("/tmp/test.json"
        template("$(format-json --scope dot-nv-pairs)\n"));
};

parser p_kv {
    kv-parser (prefix(".kv."));
};

log {
    source(s_kv);
    parser(p_kv);
    destination(d_json);
};

source s_kv {
    network(port(21514));
};

destination d_json {
    file("/tmp/test.json"
        template("$(format-json --scope dot-nv-pairs)\n"));
};

log {
    source(s_kv);
    parser {
        kv-parser (prefix(".kv."));
    };
    destination(d_json);
};

Mar  7 12:39:25 myhost MysqlClient[20824]: SYSTEM_USER:'oscar', MYSQL_USER:'my_oscar', CONNECTION_ID:23, DB_SERVER:'127.0.0.1', DB:'--', QUERY:'USE test;'

parser p_mysql {
    kv-parser(value-separator(":") prefix(".mysql."));
};