**NOTE:** XMPP compression has unresolved [security concerns](https://mail.jabber.org/pipermail/standards/2014-October/029215.html),

and this module has been removed from Prosody and renamed.

While the bandwidth usage of XMPP isn't that much, compressing the data

sent to/from your server can give significant benefits to those on slow

connections, such as dial-up or mobile networks. Prosody supports

compression for client-to-server (if your client supports it) and

server-to-server streams using the mod\_compression plugin.

# Details

mod\_compression implements [XEP-0138], and supports the zlib compression

algorithm.

## Dependencies

The XMPP protocol specifies that all clients and servers supporting

compression must support the "zlib" compression method, and this is what

Prosody uses. However you will need to install zlib support for Lua on

your system. There are different ways of doing this depending on your

system. If in doubt whether it is installed correctly, the command

`lua -lzlib` in a console should open a Lua prompt with no errors.

Debian/Ubuntu

:   `apt-get install lua-zlib`

LuaRocks

:   `luarocks install lua-zlib`

Source

:   <https://github.com/brimworks/lua-zlib>

# Usage

``` lua

modules_enabled = {

    -- Other modules

    "compression_unsafe"; -- Enable mod_compression_unsafe

}

```

## Configuration

The compression level can be set using the `compression_level` option

which can be a number from 1 to 9. Higher compression levels will use

more resources but less bandwidth.

## Example

``` lua

modules_enabled = {

    -- Other modules

    "compression_unsafe"; -- Enable mod_compression_unsafe

}

compression_level = 5

```