---

labels:

- 'Stage-Beta'

summary: 'Impose rate-limits on a MUC'

...

Introduction

============

This module allows you to control the maximum rate of 'events' in a MUC

room. This makes it useful to prevent room floods (whether malicious or

accidental).

Details

=======

This module limits the following events:

-   Room joins

-   Nick changes

-   Status changes

-   Messages (including private messages)

The limit is for the room as a whole, not individual occupants in the

room. Users with an affiliation (members, admins and owners) are not

limited.

Configuration

=============

Add the module to the MUC host (not the global modules\_enabled):

        Component "conference.example.com" "muc"

            modules_enabled = { "muc_limits" }

You can define (globally or per-MUC component) the following options:

  Name                     Default value   Description

  ------------------------ --------------- ----------------------------------------------

  muc\_event\_rate         0.5             The maximum number of events per second.

  muc\_burst\_factor       6               Allow temporary bursts of this multiple.

  muc\_max\_nick\_length   23              The maximum allowed length of user nicknames

For more understanding of how these values are used, see the algorithm

section below.

Algorithm

=========

A certain number of events are allowed per second, given by

muc\_event\_rate. An event rate of 1 allows one event per second, and

event rate of 3 allows three events per second, and 0.5 allows one event

every two seconds, and so on.

Obviously MUC conversations are not exactly steady streams of events.

Sometimes multiple people will talk at once. This is handled by the

muc\_burst\_factor option.

A burst factor of 2 will allow 2 times as many events at once, for 2

seconds, before throttling will be triggered. A factor of 5, 5 times as

many events for 5 seconds.

When the limit is reached, an error response will be generated telling

the user the MUC is overactive, and asking them to try again.

Compatibility

=============

  ------- ------------------

  trunk   Works

  0.11    Works

  0.10    Works

  0.9     Works

  0.8     Doesn't work[^1]

  ------- ------------------

[^1]: This module can be made to work in 0.8 (and *maybe* previous

    versions) of Prosody by copying the new

    [util.throttle](http://hg.prosody.im/trunk/raw-file/fc8a22936b3c/util/throttle.lua)

    into your Prosody source directory (into the util/ subdirectory).