LEEF

Available in AxoSyslog 4.9 and later.

The parse_leef FilterX function parses messages formatted in the Log Event Extended Format (LEEF) into a JSON object.

Both LEEF versions (1.0 and 2.0) are supported.

Declaration

Usage: parse_leef(<input-string>, value_separator="=", pair_separator="|", separate_extensions=false)

The first argument is the input message. Optionally, you can set the pair_separator and value_separator arguments to override their default values.

The value_separator must be a single-character string. The pair_separator can be a regular string.

The parsed JSON object has the following fields:

• For LEEF v1 messages:

  • leef_version
  • vendor_name
  • product_name
  • product_version
  • event_id
  • extensions

• For LEEF v2 messages:

  • leef_version
  • vendor_name
  • product_name
  • product_version
  • event_id
  • leef_delimiter
  • extensions

Example

The following is a LEEF-formatted message including mandatory and custom (extension) fields:

LEEF:1.0|Microsoft|MSExchange|4.0 SP1|15345|src=192.0.2.0	dst=172.50.123.1	sev=5cat=anomaly	srcPort=81	dstPort=21	usrName=john.smith

The following FilterX expression parses it and converts it into JSON format:

filterx {
    ${PARSED_MESSAGE} = json(parse_leef(${MESSAGE}));
};

The content of the JSON object for this message will be:

{
"leef_version":"1.0",
"vendor_name":"Microsoft",
"product_name":"MSExchange",
"product_version":"4.0 SP1",
"event_id":"15345",
"src":"192.0.2.0",
"dst":"172.50.123.1",
"sev":"5cat=anomaly",
"srcPort":"81",
"dstPort":"21",
"usrName":"john.smith"
}

If you set separate_extensions=true, the extensions of the message will be grouped under the extensions key:

{
"leef_version":"1.0",
"vendor_name":"Microsoft",
"product_name":"MSExchange",
"product_version":"4.0 SP1",
"event_id":"15345",
"extensions": {
    "src":"192.0.2.0",
    "dst":"172.50.123.1",
    "sev":"5cat=anomaly",
    "srcPort":"81",
    "dstPort":"21",
    "usrName":"john.smith"
    }
}

Options of LEEF parsers

The parse_leef FilterX function has the following options.

pair_separator

Specifies the character or string that separates the key-value pairs in the extensions. Default value: \t (tab).

LEEF v2 can specify the separator per message. Omitting this option uses the LEEF v2 provided separator, setting this value overrides it during parsing.

separate_extensions

Available in AxoSyslog 4.13 and later.

Starting with version 4.13, AxoSyslog parses fields from extensions to the same level as regular fields. In earlier versions, extensions were grouped under the extensions key. To keep using the extensions key, set separate_extensions=true.

Default value: false

value_separator

Specifies the character that separates the keys from the values in the extensions. Default value: =.