Internet Engineering Task Force (IETF) R. Bellis Request for Comments: 6915 Nominet UK Updates: 6155 April 2013 Category: Standards Track ISSN: 2070-1721
Flow Identity Extension for HTTP-Enabled Location Delivery (HELD)
RFC 6155 specifies an extension for the HTTP-Enabled Location Delivery (HELD) protocol, allowing the use of an IP address and port number to request a Device location based on an individual packet flow.
However, certain kinds of NAT require that identifiers for both ends of the packet flow must be specified in order to unambiguously satisfy the location request.
This document specifies an XML Schema and a URN Sub-Namespace for a Flow Identity Extension for HELD to support this requirement.
This document updates RFC 6155 by deprecating the port number elements specified therein.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available in Section 2 of RFC 5741.
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.
Work at the Emergency Location Task Group of NICC Standards Limited (the UK's telecoms industry standards body) prompted the addition of port number identifiers in HELD Identity [RFC6155] to allow HELD [RFC5985] requests for Devices that are behind NAT devices.
Subsequent analysis has determined that in the presence of particular types of NAT devices, and in particular Carrier Grade NATs, it is necessary to know the complete tuple of (Layer 3 protocol, Layer 4 protocol, source address, source port, destination address, destination port) in order to unambiguously identify a flow, and subsequently the true Device.
This document specifies an XML Schema and a URN Sub-Namespace for a Flow Identity Extension to support this requirement and provides a more generally applicable means of identifying a Device based on the parameters of a network flow of which it is an endpoint.
Since the Location Recipient may not know in advance whether the Device is behind a NAT device, the port number elements from Section 3.3 of [RFC6155] are deprecated and MUST NOT be used in new client implementations. Note that server implementations of this specification may still encounter requests formed by clients that have implemented only [RFC6155], and those requests might contain the deprecated port element.
For implementation details not specified in this document, please refer to [RFC6155] and [RFC5985].
o a "layer3" attribute with a value of "ipv4" or "ipv6".
o a "layer4" attribute with a value of "udp" [RFC0768], "tcp" [RFC0793], "sctp" [RFC4960], "dccp" [RFC4340], or a decimal integer representing any applicable protocol from the IANA Assigned Internet Protocol Numbers Registry.
o an <src> element and a <dst> element whose child elements contain the Layer 3 address (which MUST conform to the relevant "IPv4address" or "IPv6address" grammar as defined in [RFC3986]) and the Layer 4 port number of each end of the flow.
and MAY optionally contain:
o a "target" attribute with a value of "src" (default) or "dst" to indicate which end of the flow corresponds to the Target of the <locationRequest> with respect to the HELD protocol.
<xs:annotation> <xs:appinfo source="urn:ietf:params:xml:schema:geopriv:held:flow"> HELD Flow Identity</xs:appinfo> <xs:documentation source="http://www.rfc-editor.org/rfc/rfc6915.txt"> This document defines Flow Identity elements for HELD. </xs:documentation> </xs:annotation>
All of the considerations in [RFC6155] apply to the use of the mechanism defined in this document. Like [RFC6155], this specification assumes that the Location Server being queried already has access to the internal state of the network near one end of the flow being queried (for instance, access to the bindings in a NAT in the path of the flow). Clients making queries using this specification in environments where that assumption may not be true should be aware that the request provides information about that client's communications that the Location Server would not otherwise be able to discern and may represent additional privacy exposure for that client.
The author wishes to thank the members of the NICC Emergency Location Task Group, the IETF GeoPriv Working Group, and the authors of [RFC6155], from which the text for the URN and XML Schema Registrations were derived.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC 793, September 1981.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram Congestion Control Protocol (DCCP)", RFC 4340, March 2006.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 4960, September 2007.
Bellis Standards Track [Page 8]
RFC 6915 Flow Identity for HELD April 2013
[RFC6280] Barnes, R., Lepinski, M., Cooper, A., Morris, J., Tschofenig, H., and H. Schulzrinne, "An Architecture for Location and Location Privacy in Internet Applications", BCP 160, RFC 6280, July 2011.
Ray Bellis Nominet UK Edmund Halley Road Oxford OX4 4DQ United Kingdom