racket-nat-pmp

If you find that this library lacks some feature you need, or you have a suggestion for improving it, please don’t hesitate to get in touch with me!

1 Introduction

This library implements NAT-PMP, the Apple/IETF protocol for opening TCP and UDP ports on home routers.

Using this library, you can discover the external IP address of your home router, and can manage port mappings from the public internet to internal TCP and UDP ports.

2 References

NAT-PMP is currently defined in an Internet-Draft.

• The NAT-PMP Internet-Draft at the time this library was written.

• A useful quick overview of the protocol.

• NAT-PMP on Wikipedia.

3 What to require

All the functionality below can be accessed with a single require:

3.1 Getting information on local interfaces and gateways

NAT-PMP depends on being able to learn the IP address of the current default gateway. Currently, this library learns this information by running the system utility netstat and parsing its output.

As an additional convenience, this library provides utilities for discovering and classifying local interface addresses.

3.2 Timeouts

Requests made to the gateway using NAT-PMP will eventually time out if the gateway does not support NAT-PMP. In this case, an exception is raised.

3.3 Discovering the current external IP address

3.4 Low-level interface: mapping ports manually

If you can’t or don’t want to use the persistent mapping support of this library, these routines let you explicitly manage mappings with the gateway.

3.5 High-level interface: persistent mappings

Every time the externally mapped port changes (including when the mapping is first established!) the #:on-mapping callback is called with the updated mapping information. Note that the callback is invoked directly from the mapping’s thread - if it raises an exception, it will kill the persistent mapping.