## ProFTPD module `mod_qos`

The `mod_qos` module can be used to set the Differentiated Services field (RFC2474) of IP packet headers. This can dramatically aid in the handling of these packets in the network, depending on the network QoS configuration.

This module is contained in the `mod_qos` file for ProFTPD 1.3.x, and is not compiled by default. Installation instructions are discussed here.

The most current version of `mod_qos` is distributed with the ProFTPD source code.

## Directives

- QoSOptions

### QoSOptions

Syntax: QoSOptions "ctrlqos" value|"dataqos" value
Default: None
Context: server config, `<VirtualHost>`
Module: mod_qos
Compatibility: 1.3.4rc1 and later

The `QoSOptions` directive configures the QoS bits to use for the control and/or data connections.

The possible values to use are:

- cs0
- cs1
- cs2
- cs3
- cs4
- cs5
- cs6
- cs7
- af11
- af12
- af13
- af21
- af22
- af23
- af31
- af32
- af33
- af41
- af42
- af43

See RFC2474 for a better discussion of these values.

Note that while the following values are also supported, their use is deprecated, and can have adverse effects on TCP congestion control:

- lowcost
- lowdelay
- mincost
- reliability
- throughput

## Installation

For including `mod_qos` as a statically linked module in your `proftpd`, use:

      $ ./configure --with-modules=mod_qos

Alternatively, `mod_qos` could be built as a DSO module:

      $ ./configure --enable-dso --with-shared=mod_qos

Then follow the usual steps:

      $ make
      $ make install

Alternatively, if your `proftpd` was compiled with DSO support, you can use the `prxs` tool to build `mod_qos` as a shared module:

      $ prxs -c -i -d mod_qos.c

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