# Log Message Normalization Module (mmnormalize)

Module Name: mmnormalize

Available since: 6.1.2+

Author: Rainer Gerhards <rgerhards@adiscon.com>

Description:

This module provides the capability to normalize log messages via liblognorm. Thanks to liblognorm, unstructured text, like usually found in log messages, can very quickly be parsed and put into a normal form. This is done so quickly, that it should be possible to normalize events in realtime.

This module is implemented via the output module interface. This means that mmnormalize should be called just like an action. After it has been called, the normalized message properties are available and can be accessed. These properties are called the “CEE/lumberjack” properties, because liblognorm creates a format that is inspired by the CEE/lumberjack approach.

Please note: CEE/lumberjack properties are different from regular properties. They have always “$!” prepended to the property name given in the rulebase. Such a property needs to be called with %$!propertyname%.

Note that from a performance point of view mmnormalize should only be called once on each message, if possible. To do so, place all rules into a single rule base. If that is not possible, you can safely call mmnormalize multiple times. This incurs a small performance drawback.

## Module Parameters

Note: parameter names are case-insensitive.

allow_regex <boolean>

  Default: off

  Specifies if regex field-type should be allowed. Regex field-type has significantly higher computational overhead compared to other fields, so it should be avoided when another field-type can achieve the desired effect. Needs to be “on” for regex field-type to work.

## Action Parameters

Note: parameter names are case-insensitive.

ruleBase <word>

  Specifies which rulebase file is to use. If there are multiple mmnormalize instances, each one can use a different file. However, a single instance can use only a single file. This parameter or rule MUST be given, because normalization can only happen based on a rulebase. It is recommended that an absolute path name is given. Information on how to create the rulebase can be found in the liblognorm manual.

rule <array>

  (Available since: 8.26.0)

  Contains an array of strings which will be put together as the rulebase. This parameter or rulebase MUST be given, because normalization can only happen based on a rulebase.

useRawMsg <boolean>

  Default: off

  Specifies if the raw message should be used for normalization (on) or just the MSG part of the message (off).

path <word>

  Default: $!

  Specifies the JSON path under which parsed elements should be placed. By default, all parsed properties are merged into root of message properties. You can place them under a subtree, instead. You can place them in local variables, also, by setting path=”$.”.

variable <word>

  (Available since: 8.5.1)

  Specifies if a variable instead of property ‘msg’ should be used for normalization. A variable can be property, local variable, json-path etc. Please note that useRawMsg overrides this parameter, so if useRawMsg is set, variable will be ignored and raw message will be used.

## Legacy Configuration Parameters

Note: parameter names are case-insensitive.

- $mmnormalizeRuleBase <rulebase-file> - equivalent to the “ruleBase” parameter.

- $mmnormalizeUseRawMsg <on/off> - equivalent to the “useRawMsg” parameter.

## See Also

- First steps for mmnormalize

- Log normalization and special characters

- Log normalization and the leading space

- Using mmnormalize effectively with Adiscon LogAnalyzer

## Caveats/Known Bugs

None known at this time.

## Example

Sample 1:

In this sample messages are received via imtcp. Then they are normalized with the given rulebase. After that they are written in a file.

    module(load="mmnormalize")
    module(load="imtcp")

    input(type="imtcp" port="10514" ruleset="outp")

    ruleset(name="outp") {
          action(type="mmnormalize" rulebase="/tmp/rules.rulebase")
          action(type="omfile" File="/tmp/output")
    }

Sample 2:

In this sample messages are received via imtcp. Then they are normalized based on the given rules. The strings from rule are put together and are equal to a rulebase with the same content.

    module(load="mmnormalize")
    module(load="imtcp")

    input(type="imtcp" port="10514" ruleset="outp")

    ruleset(name="outp") {
          action(type="mmnormalize" rule=["rule=:%host:word% %tag:char-to:\\x3a%: no longer listening on %ip:ipv4%#%port:number%", "rule=:%host:word% %ip:ipv4% user was logged out"])
          action(type="omfile" File="/tmp/output")
    }

Sample 3:

This activates the module and applies normalization to all messages:

    module(load="mmnormalize")
    action(type="mmnormalize" ruleBase="/path/to/rulebase.rb")

The same in legacy format:

    $ModLoad mmnormalize
    $mmnormalizeRuleBase /path/to/rulebase.rb
    *.* :mmnormalize:

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`

See also

Contributing to `Rsyslog`:

- Source project: rsyslog project README.

- Documentation: rsyslog-doc project README

Copyright 2008-2023 Rainer Gerhards (Großrinderfeld), and Others.