---
labels:
- 'Stage-Beta'
summary: 'Connection-level rate limiting'
...

Introduction
============

On some servers, especially public ones, it is desired to make sure that
everyone gets their fair share of system resources (and no more).

mod\_limits allows you to specify traffic bandwidth limits, preventing
any single connection hogging the server's CPU, RAM and bandwidth.

Details
=======

mod\_limits detects when a connection has exceeded its traffic allowance
and temporarily ignores a connection. Due to the way TCP and the OS's
network API works no data is lost, only slowed.

Configuration
=============

Currently mod\_limits is configured per connection type. The possible
connection types are:

-   c2s
-   s2sin
-   s2sout
-   component

The limits are specified like so in the **global** section of your
config (they cannot be per-host):

``` {.lua}
limits = {
  c2s = {
    rate = "3kb/s";
    burst = "2s";
  };
  s2sin = {
    rate = "10kb/s";
    burst = "5s";
  };
}
```

All units are in terms of *bytes*, not *bits*, so that "kb/s" is
interpreted as "kilobytes per second", where a kilobyte is 1000 bytes.

Compatibility
=============

  ----- -------------------
  0.9   Works
  0.8   Doesn't work(\*)
  ----- -------------------

(\*) This module can be made to work in 0.8 if you do two things:

1.  Install
    [util.throttle](http://hg.prosody.im/0.9/raw-file/d46948d3018a/util/throttle.lua)
    into your Prosody source's util/ directory.
2.  If you use libevent apply [this
    patch](http://prosody.im/patches/prosody08-mod-limits-fix.patch) to
    net/server\_event.lua.
