--- 1/draft-ietf-behave-rfc3489bis-00.txt 2006-02-04 22:51:03.000000000 +0100 +++ 2/draft-ietf-behave-rfc3489bis-01.txt 2006-02-04 22:51:04.000000000 +0100 @@ -1,128 +1,130 @@ BEHAVE J. Rosenberg Internet-Draft Cisco Systems -Expires: April 16, 2005 C. Huitema +Expires: August 22, 2005 C. Huitema Microsoft R. Mahy - Cisco Systems - October 16, 2004 + Airspace + February 21, 2005 Simple Traversal of UDP Through Network Address Translators (NAT) (STUN) - draft-ietf-behave-rfc3489bis-00 + draft-ietf-behave-rfc3489bis-01 Status of this Memo - By submitting this Internet-Draft, I certify that any applicable - patent or other IPR claims of which I am aware have been disclosed, - and any of which I become aware will be disclosed, in accordance with + This document is an Internet-Draft and is subject to all provisions + of section 3 of RFC 3667. By submitting this Internet-Draft, each + author represents that any applicable patent or other IPR claims of + which he or she is aware have been or will be disclosed, and any of + which he or she become aware will be disclosed, in accordance with RFC 3668. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet-Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. - This Internet-Draft will expire on April 16, 2005. + This Internet-Draft will expire on August 22, 2005. Copyright Notice - Copyright (C) The Internet Society (2004). All Rights Reserved. + Copyright (C) The Internet Society (2005). Abstract Simple Traversal of UDP Through NATs (STUN) is a lightweight protocol that provides the ability for applications to determine the public IP addresses allocated to them by the NAT. These addresses can be placed into protocol payloads where a client needs to provide a publically routable IP address. STUN works with many existing 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. Table of Contents 1. Applicability Statement . . . . . . . . . . . . . . . . . . . 4 - 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 5. NAT Variations . . . . . . . . . . . . . . . . . . . . . . . . 9 - 6. Overview of Operation . . . . . . . . . . . . . . . . . . . . 10 - 7. Message Overview . . . . . . . . . . . . . . . . . . . . . . . 13 - 8. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 15 - 8.1 Binding Requests . . . . . . . . . . . . . . . . . . . . . 15 - 8.2 Shared Secret Requests . . . . . . . . . . . . . . . . . . 18 - 9. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 21 - 9.1 Discovery . . . . . . . . . . . . . . . . . . . . . . . . 21 - 9.2 Obtaining a Shared Secret . . . . . . . . . . . . . . . . 22 - 9.3 Formulating the Binding Request . . . . . . . . . . . . . 23 - 9.4 Processing Binding Responses . . . . . . . . . . . . . . . 24 - 9.5 Using the Mapped Address . . . . . . . . . . . . . . . . . 26 - 10. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 28 - 10.1 Message Header . . . . . . . . . . . . . . . . . . . . . . 28 - 10.2 Message Attributes . . . . . . . . . . . . . . . . . . . . 29 - 10.2.1 MAPPED-ADDRESS . . . . . . . . . . . . . . . . . . . . 30 - 10.2.2 RESPONSE-ADDRESS . . . . . . . . . . . . . . . . . . . 31 - 10.2.3 CHANGED-ADDRESS . . . . . . . . . . . . . . . . . . . 31 - 10.2.4 CHANGE-REQUEST . . . . . . . . . . . . . . . . . . . . 31 - 10.2.5 SOURCE-ADDRESS . . . . . . . . . . . . . . . . . . . . 32 - 10.2.6 USERNAME . . . . . . . . . . . . . . . . . . . . . . . 32 - 10.2.7 PASSWORD . . . . . . . . . . . . . . . . . . . . . . . 32 - 10.2.8 MESSAGE-INTEGRITY . . . . . . . . . . . . . . . . . . 32 - 10.2.9 ERROR-CODE . . . . . . . . . . . . . . . . . . . . . . 33 - 10.2.10 UNKNOWN-ATTRIBUTES . . . . . . . . . . . . . . . . . 34 - 10.2.11 REFLECTED-FROM . . . . . . . . . . . . . . . . . . . 34 - 10.2.12 XOR-MAPPED-ADDRESS . . . . . . . . . . . . . . . . . 34 - 10.2.13 XOR-ONLY . . . . . . . . . . . . . . . . . . . . . . 35 - 10.2.14 SERVER . . . . . . . . . . . . . . . . . . . . . . . 35 - 11. Security Considerations . . . . . . . . . . . . . . . . . . 37 - 11.1 Attacks on STUN . . . . . . . . . . . . . . . . . . . . . 37 - 11.1.1 Attack I: DDOS Against a Target . . . . . . . . . . . 37 - 11.1.2 Attack II: Silencing a Client . . . . . . . . . . . . 37 - 11.1.3 Attack III: Assuming the Identity of a Client . . . . 38 - 11.1.4 Attack IV: Eavesdropping . . . . . . . . . . . . . . . 38 - 11.2 Launching the Attacks . . . . . . . . . . . . . . . . . . 38 - 11.2.1 Approach I: Compromise a Legitimate STUN Server . . . 39 - 11.2.2 Approach II: DNS Attacks . . . . . . . . . . . . . . . 39 - 11.2.3 Approach III: Rogue Router or NAT . . . . . . . . . . 39 - 11.2.4 Approach IV: MITM . . . . . . . . . . . . . . . . . . 40 - 11.2.5 Approach V: Response Injection Plus DoS . . . . . . . 40 - 11.2.6 Approach VI: Duplication . . . . . . . . . . . . . . . 40 - 11.3 Countermeasures . . . . . . . . . . . . . . . . . . . . . 41 - 11.4 Residual Threats . . . . . . . . . . . . . . . . . . . . . 43 - 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 44 - 13. IAB Considerations . . . . . . . . . . . . . . . . . . . . . 45 - 13.1 Problem Definition . . . . . . . . . . . . . . . . . . . . 45 - 13.2 Exit Strategy . . . . . . . . . . . . . . . . . . . . . . 45 - 13.3 Brittleness Introduced by STUN . . . . . . . . . . . . . . 46 - 13.4 Requirements for a Long Term Solution . . . . . . . . . . 47 - 13.5 Issues with Existing NAPT Boxes . . . . . . . . . . . . . 48 - 13.6 In Closing . . . . . . . . . . . . . . . . . . . . . . . . 49 - 14. Changes Since RFC 3489 . . . . . . . . . . . . . . . . . . . 50 - 15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 51 - 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 52 - 16.1 Normative References . . . . . . . . . . . . . . . . . . . . 52 - 16.2 Informative References . . . . . . . . . . . . . . . . . . . 52 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 53 - Intellectual Property and Copyright Statements . . . . . . . . 55 + 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 + 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 4. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 5 + 5. NAT Variations . . . . . . . . . . . . . . . . . . . . . . . . 6 + 6. Overview of Operation . . . . . . . . . . . . . . . . . . . . 6 + 7. Message Overview . . . . . . . . . . . . . . . . . . . . . . . 9 + 8. Server Behavior . . . . . . . . . . . . . . . . . . . . . . . 10 + 8.1 Binding Requests . . . . . . . . . . . . . . . . . . . . . 10 + 8.2 Shared Secret Requests . . . . . . . . . . . . . . . . . . 14 + 9. Client Behavior . . . . . . . . . . . . . . . . . . . . . . . 16 + 9.1 Discovery . . . . . . . . . . . . . . . . . . . . . . . . 16 + 9.2 Obtaining a Shared Secret . . . . . . . . . . . . . . . . 17 + 9.3 Formulating the Binding Request . . . . . . . . . . . . . 18 + 9.4 Processing Binding Responses . . . . . . . . . . . . . . . 19 + 9.5 Using the Mapped Address . . . . . . . . . . . . . . . . . 21 + 10. Protocol Details . . . . . . . . . . . . . . . . . . . . . . 22 + 10.1 Message Header . . . . . . . . . . . . . . . . . . . . . . 22 + 10.2 Message Attributes . . . . . . . . . . . . . . . . . . . . 23 + 10.2.1 MAPPED-ADDRESS . . . . . . . . . . . . . . . . . . . . 25 + 10.2.2 RESPONSE-ADDRESS . . . . . . . . . . . . . . . . . . . 26 + 10.2.3 CHANGED-ADDRESS . . . . . . . . . . . . . . . . . . . 26 + 10.2.4 CHANGE-REQUEST . . . . . . . . . . . . . . . . . . . . 26 + 10.2.5 SOURCE-ADDRESS . . . . . . . . . . . . . . . . . . . . 26 + 10.2.6 USERNAME . . . . . . . . . . . . . . . . . . . . . . . 27 + 10.2.7 PASSWORD . . . . . . . . . . . . . . . . . . . . . . . 27 + 10.2.8 MESSAGE-INTEGRITY . . . . . . . . . . . . . . . . . . 27 + 10.2.9 ERROR-CODE . . . . . . . . . . . . . . . . . . . . . . 27 + 10.2.10 UNKNOWN-ATTRIBUTES . . . . . . . . . . . . . . . . . 29 + 10.2.11 REFLECTED-FROM . . . . . . . . . . . . . . . . . . . 29 + 10.2.12 XOR-MAPPED-ADDRESS . . . . . . . . . . . . . . . . . 29 + 10.2.13 XOR-ONLY . . . . . . . . . . . . . . . . . . . . . . 30 + 10.2.14 SERVER . . . . . . . . . . . . . . . . . . . . . . . 30 + 11. Security Considerations . . . . . . . . . . . . . . . . . . 31 + 11.1 Attacks on STUN . . . . . . . . . . . . . . . . . . . . . 31 + 11.1.1 Attack I: DDOS Against a Target . . . . . . . . . . . 31 + 11.1.2 Attack II: Silencing a Client . . . . . . . . . . . . 31 + 11.1.3 Attack III: Assuming the Identity of a Client . . . . 32 + 11.1.4 Attack IV: Eavesdropping . . . . . . . . . . . . . . . 32 + 11.2 Launching the Attacks . . . . . . . . . . . . . . . . . . 32 + 11.2.1 Approach I: Compromise a Legitimate STUN Server . . . 33 + 11.2.2 Approach II: DNS Attacks . . . . . . . . . . . . . . . 33 + 11.2.3 Approach III: Rogue Router or NAT . . . . . . . . . . 33 + 11.2.4 Approach IV: MITM . . . . . . . . . . . . . . . . . . 34 + 11.2.5 Approach V: Response Injection Plus DoS . . . . . . . 34 + 11.2.6 Approach VI: Duplication . . . . . . . . . . . . . . . 34 + 11.3 Countermeasures . . . . . . . . . . . . . . . . . . . . . 35 + 11.4 Residual Threats . . . . . . . . . . . . . . . . . . . . . 37 + 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 37 + 13. IAB Considerations . . . . . . . . . . . . . . . . . . . . . 37 + 13.1 Problem Definition . . . . . . . . . . . . . . . . . . . . 37 + 13.2 Exit Strategy . . . . . . . . . . . . . . . . . . . . . . 38 + 13.3 Brittleness Introduced by STUN . . . . . . . . . . . . . . 38 + 13.4 Requirements for a Long Term Solution . . . . . . . . . . 40 + 13.5 Issues with Existing NAPT Boxes . . . . . . . . . . . . . 41 + 13.6 In Closing . . . . . . . . . . . . . . . . . . . . . . . . 42 + 14. Changes Since RFC 3489 . . . . . . . . . . . . . . . . . . . 42 + 15. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 43 + 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 43 + 16.1 Normative References . . . . . . . . . . . . . . . . . . . . 43 + 16.2 Informative References . . . . . . . . . . . . . . . . . . . 43 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 45 + Intellectual Property and Copyright Statements . . . . . . . . 46 1. Applicability Statement This protocol is not a cure-all for the problems associated with NAT. 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 (defined below), which are common in large enterprises. STUN does not work when it is used to obtain an address to communicate with a peer which happens to be behind the @@ -1986,48 +2034,46 @@ [19] Rosenberg, J., Weinberger, J., Huitema, C. and R. Mahy, "STUN - Simple Traversal of User Datagram Protocol (UDP) Through Network Address Translators (NATs)", RFC 3489, March 2003. [20] Handley, M. and V. Jacobson, "SDP: Session Description Protocol", RFC 2327, April 1998. [21] Rosenberg, J., "Interactive Connectivity Establishment (ICE): A Methodology for Network Address Translator (NAT) Traversal for Multimedia Session Establishment Protocols", - draft-ietf-mmusic-ice-02 (work in progress), July 2004. + draft-ietf-mmusic-ice-03 (work in progress), October 2004. Authors' Addresses Jonathan Rosenberg Cisco Systems 600 Lanidex Plaza Parsippany, NJ 07054 US Phone: +1 973 952-5000 - EMail: jdrosen@dynamicsoft.com + EMail: jdrosen@cisco.com URI: http://www.jdrosen.net + Christian Huitema Microsoft One Microsoft Way Redmond, WA 98052 US EMail: huitema@microsoft.com Rohan Mahy - Cisco Systems - 5617 Scotts Valley Dr - Scotts Valley, CA 95066 - US + Airspace - EMail: rohan@cisco.com + EMail: rohan@ekabal.com Intellectual Property Statement The IETF takes no position regarding the validity or scope of any Intellectual Property Rights or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; nor does it represent that it has made any independent effort to identify any such rights. Information on the procedures with respect to rights in RFC documents can be @@ -2051,18 +2097,18 @@ This document and the information contained herein are provided on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. Copyright Statement - Copyright (C) The Internet Society (2004). This document is subject + Copyright (C) The Internet Society (2005). This document is subject to the rights, licenses and restrictions contained in BCP 78, and except as set forth therein, the authors retain all their rights. Acknowledgment Funding for the RFC Editor function is currently provided by the Internet Society.