Subject: [midcom] Protocol Action: STUN - Simple Traversal of UDP Through Network Address Translators to Proposed Standard

From: The IESG <[email-masked]>
Date: Thu, 26 Dec 2002 17:22:43 -0500

The IESG has approved the Internet-Draft 'STUN - Simple Traversal of 
UDP Through Network Address Translators' <draft-ietf-midcom-stun-05.txt> 
as a Proposed Standard. This document is the product of the Middlebox
Communication Working Group. The IESG contact persons are Allison 
Mankin and Scott Bradner.

Technical Summary
   
This document describes Simple Traversal of UDP Through NATs (STUN). 
STUN is a lightweight protocol that allows applications to discover 
the presenceand types of Network Address Translators (NATs) and 
firewalls between them and the public Internet. It also provides the 
ability for applications to determine the public IP addresses allocated 
to them by the NAT. STUN works with many existing types of NATs, and 
does not require any special behavior from them. As a result, it allows 
a wide variety of applications to work through existing NAT 
infrastructure.

This protocol is not a cure-all for the problems associated with NATs.
It does not enable incoming TCP connections through NAT. It allows 
incoming UDP packets through NAT, but only through a subset of existing 
NAT types. In particular, STUN does not enable incoming UDP packets 
through symmetric NATs, which are common in large enterprises. STUN's 
discovery procedures are based on assumptions on NAT treatment of UDP; 
such assumptions may prove invalid down the road as new NAT devices are 
deployed.

STUN is a simple client-server protocol. A client sends a request to a
server on the Internet, and the server returns a response. The server
examines the source IP address and port of the request, and copies them
into a response that is sent back to the client.
   
Working Group Summary
   
The midcom working group supported publication of this document. 
Security issues raised during IETF last call have been addressed in the 
current revision of the document.
   
Protocol Quality
   
This document was review for the IESG by Scott Bradner and Eric 
Rescorla.  The area directors know of recent interoperability testing 
among several servers and clients in pre-commercial state, where the 
functions of STUN were successfully tested against each of the 
NAT varieties currently targeted.

RFC Editor Note:
	Please add the following sentence to the IANA Considerations 
	section:
"Any future extensions will establish any needed regsteries."

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