syslog-ng Premium Edition 7.0.12 - Administration Guide

Options of XML parsers

The XML parser has the following options.

drop-invalid

Description: If set, messages with an invalid XML will be dropped entirely.

exclude-tags

Description: The XML parser matches tags against the listed globs. If there is a match, the given subtree of the XML will be omitted.

parser xml_parser {
       xml(template("$MSG") exclude_tags("tag1", "tag2", "inner*"));
};

<tag1>Text1</tag1><tag2>Text2</tag2><tag3>Text3<innertag>TextInner</innertag></tag3>

{"_xml":{"tag3":"Text3"}}

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.

The prefix() option is optional and its default value is ".xml".

strip-whitespaces

Description: Strip the whitespaces from the XML text nodes before adding them to the message.

parser xml_parser {
       xml(template("$MSG") strip_whitespaces(yes));
};

<tag1> Tag </tag1>

{"_xml":{"tag1":"Tag"}}

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 dates and timestamps

The date parser can extract dates from non-syslog messages. It operates by default on the ${MSG} part of the log message, but can operate on any template or field provided. The parsed date will be available as the sender date (that is, the ${S_DATE}, ${S_ISODATE}, ${S_MONTH}, and so on, and related macros). (To store the parsed date as the received date, use the timestamp(recvd) option.)

Note that parsing will fail if the format string does not match the entire template or field. Since by default syslog-ng PE uses the ${MSG} part of the log message, parsing will fail, unless the log message contains only a date, but that is unlikely, so practically you will have to segment the message (for example, using a csv-parser()) before using the date-parser(). You can also use date-parser() to parse dates received in a JSON or key-value-formatted log message.

parser parser_name {
    date-parser(
        format("<format-string-for-the-date>")
        template("<field-to-parse>'")
    );
};

source s_file {
    file("/tmp/input" flags(no-parse));
};

destination d_file {
    file( "/tmp/output" template("${S_ISODATE} ${MESSAGE}\n") );
};

log {
    source(s_file);
    date-parser(format("%d/%b/%Y:%H:%M:%S %Z") template("${MY_DATE}") );
    destination(d_file);
};

date-parser(format("%d/%b/%Y:%H:%M:%S %Z") template("$(substr ${MSG} 0 24)") );

Options of date-parser() parsers

The date-parser() parser has the following options.

format()

Description: Specifies the format how syslog-ng PE should parse the date. You can use the following format elements:

%%      PERCENT
%a      day of the week, abbreviated
%A      day of the week
%b      month abbr
%B      month
%c      MM/DD/YY HH:MM:SS
%C      ctime format: Sat Nov 19 21:05:57 1994
%d      numeric day of the month, with leading zeros (eg 01..31)
%e      like %d, but a leading zero is replaced by a space (eg  1..32)
%D      MM/DD/YY
%G      GPS week number (weeks since January 6, 1980)
%h      month, abbreviated
%H      hour, 24 hour clock, leading 0's)
%I      hour, 12 hour clock, leading 0's)
%j      day of the year
%k      hour
%l      hour, 12 hour clock
%L      month number, starting with 1
%m      month number, starting with 01
%M      minute, leading 0's
%n      NEWLINE
%o      ornate day of month -- "1st", "2nd", "25th", etc.
%p      AM or PM
%P      am or pm (Yes %p and %P are backwards :)
%q      Quarter number, starting with 1
%r      time format: 09:05:57 PM
%R      time format: 21:05
%s      seconds since the Epoch, UCT
%S      seconds, leading 0's
%t      TAB
%T      time format: 21:05:57
%U      week number, Sunday as first day of week
%w      day of the week, numerically, Sunday == 0
%W      week number, Monday as first day of week
%x      date format: 11/19/94
%X      time format: 21:05:57
%y      year (2 digits)
%Y      year (4 digits)
%Z      timezone in ascii. eg: PST
%z      timezone in format -/+0000

For example, for the date 01/Jan/2016:13:05:05 PST use the following format string: format("%d/%b/%Y:%H:%M:%S %Z")

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}).

timestamp()

Description: Determines if the parsed date values are treated as sent or received date. If you use timezone(stamp), syslog-ng PE adds the parsed date to the S_ macros (corresponding to the sent date). If you use timezone(recvd), syslog-ng PE adds the parsed date to the R_ macros (corresponding to the received date).

timezone()

Description: If this option is set, syslog-ng PE assumes that the parsed timestamp refers to the specified timezone. The timezone set in the timezone() option overrides any timezone information parsed from the timestamp.

The timezone can be specified as using the name of the (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.

The Cisco Parser

The Cisco Parser can parse the log messages of various Cisco devices. The messages of these devices often do not completely comply with the syslog RFCs, making them difficult to parse. The cisco-parser() of syslog-ng PE solves this problem, and can separate these log messages to name-value pairs, extracting also the Cisco-specific values, for example, the mnemonic. For details on using value-pairs in syslog-ng PE see Structuring macros, metadata, and other value-pairs. The parser can parse variations of the following message format:

<pri>(sequence: )?(origin-id: )?(timestamp? timezone?: )?%msg

For example:

<189>29: foo: *Apr 29 13:58:40.411: %SYS-5-CONFIG_I: Configured from console by console
<190>30: foo: *Apr 29 13:58:46.411: %SYS-6-LOGGINGHOST_STARTSTOP: Logging to host 192.168.1.239 stopped - CLI initiated
<190>31: foo: *Apr 29 13:58:46.411: %SYS-6-LOGGINGHOST_STARTSTOP: Logging to host 192.168.1.239 started - CLI initiated
<189>32: 0.0.0.0: *Apr 29 13:59:12.491: %SYS-5-CONFIG_I: Configured from console by console

Note that not every Cisco log message conforms to this format. If you find a message that the cisco-parser() cannot properly parse, send it to documentation@balabit.com so we can improve the parser.

The syslog-ng PE application normalizes the parsed log messages into the following format:

${MESSAGE}=%FAC-SEV-MNEMONIC: message
${HOST}=origin-id

By default, the Cisco-specific fields are extracted into the following name-value pairs:${.cisco.facility}, ${.cisco.severity}, ${.cisco.mnemonic}. You can change the prefix using the prefix option.

@version: 7.0
@include "scl.conf"
log {
    source { udp(flags(no-parse)); };
    parser { cisco-parser(); };
    destination { ... };
};

Note that you have to disable message parsing in the source using the flags(no-parse) option for the parser to work.

The cisco-parser() is actually a reusable configuration snippet configured to parse Cisco messages. For details on using or writing such configuration snippets, see Reusing configuration blocks. You can find the source of this configuration snippet on GitHub.

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.

By default, cisco-parser() uses the cisco. prefix. To modify it, use the following format:

parser { cisco-parser(prefix("myprefix.")); };