PCP working group S. Cheshire Internet-Draft Apple Updates: 6887 (if approved) May 29, 2013 Intended status: Standards Track Expires: November 30, 2013 PCP Unsupported Family Error draft-cheshire-pcp-unsupp-family-01 Abstract The Port Control Protocol allows clients to request mappings in NAT gateways and firewalls. The PCP UNSUPP_FAMILY error code enables PCP servers to inform clients when the requested external address family is not supported. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on November 30, 2013. Copyright Notice Copyright (c) 2013 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Cheshire Expires November 30, 2013 [Page 1] Internet-Draft PCP UNSUPP_FAMILY May 2013 1. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in "Key words for use in RFCs to Indicate Requirement Levels" [RFC2119]. 2. Introduction The Port Control Protocol [RFC6887] allows clients to request mappings in NAT gateways and firewalls. A client can request a mapping to an external IPv4 address or to an external IPv6 address. The client signifies which family of external address it desires by the type of address it puts into the Suggested External Address field. If the client wants an external IPv4 address, then it populates the Suggested External Address field with an IPv4-mapped IPv6 address (the first 80 bits set to zero, the next 16 set to one). This includes the case of the all-zeros IPv4 address (::ffff:0:0). If the client wants an external IPv6 address, then it populates the Suggested External Address field with a native IPv6 address. This includes the case of the all-zeros IPv6 address (::). However, some devices may not be able to provide the requested external address family. For example, an IPv4-only NAT cannot provide an external IPv6 address. Note that while the specific address placed in the Suggested External Address field is merely a suggestion that the PCP server is free to ignore, the address family is not. If the suggested address *family* cannot be provided by this PCP server, then it MUST return a PCP error reply containing the UNSUPP_FAMILY error code. The ability to provide the requested external address family may depend on the client's internal address. For example, a gateway that supports traditional NAT44, and native IPv6, but not NAT64, is able to provide mappings from an internal IPv4 address to an external IPv4 address, and mappings from an internal IPv6 address to an external IPv6 address, but not mappings from an internal IPv6 address to an external IPv4 address. When such a gateway receives a request to map an internal IPv4 address to an external IPv4 address it MUST return an external IPv4 address, if available, but when it receives a request to map an internal IPv6 address to an external IPv4 address it MUST return an UNSUPP_FAMILY error. Cheshire Expires November 30, 2013 [Page 2] Internet-Draft PCP UNSUPP_FAMILY May 2013 3. IANA Considerations IANA should allocate the following PCP Result Code: 14 UNSUPP_FAMILY: Unsupported external address family, e.g., IPv6 in a NAT that handles only IPv4. This is a long lifetime error. 4. Security Considerations This new error code leaks no sensitive information and creates no new security vulnerabilities. 5. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC6887] Wing, D., Cheshire, S., Boucadair, M., Penno, R., and P. Selkirk, "Port Control Protocol (PCP)", RFC 6887, April 2013. Author's Address Stuart Cheshire Apple Inc. 1 Infinite Loop Cupertino, California 95014 USA Phone: +1 408 974 3207 Email: cheshire@apple.com Cheshire Expires November 30, 2013 [Page 3]