RSyslog Documentation

RFC5424 structured data parsing module (mmpstrucdata)

Module Name: mmpstrucdata

Author: Rainer Gerhards <>

Available since: 7.5.4


The mmpstrucdata parses the structured data of RFC5424 into the message json variable tree. The data parsed, if available, is stored under “jsonRoot!rfc5424-sd!…”. Please note that only RFC5424 messages will be processed.

The difference of RFC5424 is in the message layout: the SYSLOG-MSG part only contains the structured-data part instead of the normal message part. Further down you can find a example of a structured-data part.

Module Configuration Parameters:

Note: parameter names are case-insensitive.

Currently none.

Action Confguration Parameters:

Note: parameter names are case-insensitive.

  • jsonRoot - default “!”

    Specifies into which json container the data shall be parsed to.

  • sd_name.lowercase - default “on”

    Available: rsyslog 8.32.0 and above

    Specifies if sd names (SDID) shall be lowercased. If set to “on”, this is the case, if “off” than not. The default of “on” is used because that was the traditional mode of operations. It it generally advised to change the parameter to “off” if not otherwise required.

See Also

Caveats/Known Bugs:

  • this module is currently experimental; feedback is appreciated

  • property names are treated case-insensitive in rsyslog. As such, RFC5424 names are treated case-insensitive as well. If such names only differ in case (what is not recommended anyways), problems will occur.

  • structured data with duplicate SD-IDs and SD-PARAMS is not properly processed


Below you can find a structured data part of a random message which has three parameters.

[exampleSDID@32473 iut="3" eventSource="Application"eventID="1011"]

In this snippet, we parse the message and emit all json variable to a file with the message anonymized. Note that once mmpstrucdata has run, access to the original message is no longer possible (execept if stored in user variables before anonymization).

module(load="mmpstrucdata") action(type="mmpstrucdata")
template(name="jsondump" type="string" string="%msg%: %$!%\\n")
action(type="omfile" file="/path/to/log" template="jsondump")

A more practical one:

Take this example message (inspired by RFC5424 sample;)):

<34>1 2003-10-11T22:14:15.003Z su - ID47 [exampleSDID@32473 iut="3" eventSource="Application" eventID="1011"][id@2 test="tast"] BOM'su root' failed for lonvick on /dev/pts/8

We apply this configuration:

module(load="mmpstrucdata") action(type="mmpstrucdata")
template(name="sample2" type="string" string="ALL: %$!%\\nSD:
%rawmsg%\\n\\n") action(type="omfile" file="/path/to/log"

This will output:

ALL: { "rfc5424-sd": { "examplesdid@32473": { "iut": "3", "eventsource": "Application", "eventid": "1011" }, "id@2": { "test": "tast" } } } SD: { "examplesdid@32473": { "iut": "3", "eventsource": "Application", "eventid": "1011" }, "id@2": { "test": "tast" } } IUT:3 RAWMSG: <34>1 2003-10-11T22:14:15.003Z su - ID47 [exampleSDID@32473 iut="3" eventSource="Application" eventID="1011"][id@2 test="tast"] BOM'su root' failed for lonvick on /dev/pts/8

As you can seem, you can address each of the individual items. Note that the case of the RFC5424 parameter names has been converted to lower case.

See also

Help with configuring/using Rsyslog:

  • Mailing list - best route for general questions

  • GitHub: rsyslog source project - detailed questions, reporting issues that are believed to be bugs with Rsyslog

  • Stack Exchange (View, Ask) - experimental support from rsyslog community

See also

Contributing to Rsyslog:

Copyright 2008-2020 Rainer Gerhards (Großrinderfeld), and Others.

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