Self-Address Fixing Evolution (SAFE) -- STUN Controlled Middlebox Traversal

This Wiki provides information for an upcoming Bar-BOF at IETF#69 about STUN Controlled Middlebox Traversal. This work is about the evolution of the protocol and procedures of RFC 3489 (STUN) and draft-ietf-behave-rfc3489bis, so that NATs and firewalls can be discovered, queried, and controlled.

Introduction

Simple Traversal Underneath NAT (STUN) is a mechanism for traversing NATs. STUN requests are transmitted through a NAT to external STUN servers. While this works very well, its two primary drawbacks are the inability to modify the properties of a NAT binding and the need to query a public STUN server for every new NAT binding (e.g., every phone call). These drawbacks require frequent messages which present a load on servers (like SIP servers and STUN servers) and are bad for low speed access networks, such as cellular access.

The STUN Control document describes two mechanisms to discover NATs and firewalls and a mechanism to query and control them. With these mechanisms, binding discovery and keepalive traffic can be reduced to involve only the necessary NATs or firewalls. At the same time, backwards compatibility with NATs and firewalls that do not support STUN Control is retained, which allows for incremental deployment of these mechanisms.

Unlike some other techniques (e.g., UPnP, MIDCOM, Bonjour), STUN does not interact directly with the NAT. Thus, STUN cannot request additional services from the NAT, such as longer lifetimes that would reduce keepalive messages. Furthermore, allocating new NAT bindings (e.g., each phone call) requires communication with a STUN server located somewhere on the Internet.

This work is about an extension of STUN, called STUN Control, to add STUN functionality to NATs and/or firewalls in order to allow an end host to interact with them.

Purpose of the Bar-BOF

The Bar-BOF has two goals:

• Inform participants about the envisioned solution approach
• Determine interest in this work

Mailing List

The topic of STUN Control is discussed on the SAFE mailing list.

Participants

• Philip Matthews
• Lars Eggert
• Rémi Denis-Courmont
• Hannes Tschofenig
• Dan Wing
• Miguel Garcia
• Christian Schmidt
• Teemu Savolainen
• Magnus Westerlund
• Colin Perkins
• Paul Francis
• Bajko Gabor
• Markus Isomaki
• Lixia Zhang
• Jonathan Rosenberg
• Bruce Lowekamp

Logistics

When?

• SUNDAY, July 22, 2007 from 8pm to 9pm

Bar-BOF Chair

• Dan Wing <dwing@cisco.com>

Where?

• We will meet at the IETF registration desk.

References

• D. Wing, J. Rosenberg, and H. Tschofenig: "Discovering, Querying, and Controlling Firewalls and NATs using STUN", http://tools.ietf.org/id/draft-wing-behave-nat-control-stun-usage-03.txt, July 2007.

• L. Eggert, P. Sarolahti, R. Denis-Courmont, V. Stirbu, and H. Tschofenig: "A Survey of Protocols to Control Network Address Translators and Firewalls", http://tools.ietf.org/id/draft-eggert-middlebox-control-survey-01.txt, July 2007.

MiddleboxTraversal Web Utilities