NAT-PMP 1.0.1

Introduction

NAT-PMP (Network Address Translation Port Mapping Protocol) implements the NAT-PMP protocol developed by Apple as a Python library and client. Use the client to manage port mappings on any NAT-PMP compatible router, typically limited to Apple AirPort base stations.

Installation

NAT-PMP is published to PyPI. Use your favorite installer to install the package for Python 2 or Python 3.

pip install NAT-PMP

Library

The library provides a set of high-level and low-level functions to interact via the NAT-PMP protocol. The functions map_port and get_public_address provide the two high-level functions offered by NAT-PMP. Responses are stored as Python objects.

Client

NAT-PMP provides a command-line client. After installing the package, the client should be installed as a console script natpmp-client. If that script does not appear on the command line, it may also be invoked with python -m natpmp.client.

Invoke the command with --help to get the usage, for example:

$ natpmp-client --help
usage: natpmp-client [-h] [-u] [-l LIFETIME] [-g GATEWAY]
                     public_port private_port

positional arguments:
  public_port
  private_port

optional arguments:
  -h, --help            show this help message and exit
  -u, --udp
  -l LIFETIME, --lifetime LIFETIME
                        lifetime in seconds
  -g GATEWAY, --gateway GATEWAY
                        gateway IP address

natpmp-client 60010 60010

natpmp-client -u -l 1800 60009 60009

natpmp-client -g 10.0.1.1 60011 60022

Caveats

This is an incomplete implementation of the specification. When the router reboots, all dynamic mappings are lost. The specification provides for notification packets to be sent by the router to each client when this happens. There is no support in this library and client to monitor for such notifications, nor does it implement a daemon process to do so. The specification recommends queuing requests – that is, all NAT-PMP interactions should happen serially. This simple library does not queue requests – if you abuse it with multithreading, it will send those requests in parallel and possibly overwhelm the router.

The library will attempt to auto-detect your NAT gateway. This is done via a popen to netstat on BSDs/Darwin and ip on Linux. This is likely to fail miserably, depending on how standard the output is. In the library, a keyword argument is provided to override the default and specify your own gateway address. In the client, use the -g switch to manually specify your gateway.