draft-ietf-dhc-dhcpv6-privacy-02.txt   draft-ietf-dhc-dhcpv6-privacy-03.txt 
dhc S. Krishnan dhc S. Krishnan
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Informational T. Mrugalski Intended status: Informational T. Mrugalski
Expires: June 29, 2016 ISC Expires: July 23, 2016 ISC
S. Jiang S. Jiang
Huawei Technologies Co., Ltd Huawei Technologies Co., Ltd
December 27, 2015 January 20, 2016
Privacy considerations for DHCPv6 Privacy considerations for DHCPv6
draft-ietf-dhc-dhcpv6-privacy-02 draft-ietf-dhc-dhcpv6-privacy-03
Abstract Abstract
DHCPv6 is a protocol that is used to provide addressing and DHCPv6 is a protocol that is used to provide addressing and
configuration information to IPv6 hosts. This document described the configuration information to IPv6 hosts. This document described the
privacy issues associated with the use of DHCPv6 by the Internet privacy issues associated with the use of DHCPv6 by the Internet
users. It is intended to be an analysis of the present situation and users. It is intended to be an analysis of the present situation and
doe not propose any solutions. doe not propose any solutions.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 29, 2016. This Internet-Draft will expire on July 23, 2016.
Copyright Notice Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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4. Existing Mechanisms That Affect Privacy . . . . . . . . . . . 8 4. Existing Mechanisms That Affect Privacy . . . . . . . . . . . 8
4.1. Temporary addresses . . . . . . . . . . . . . . . . . . . 8 4.1. Temporary addresses . . . . . . . . . . . . . . . . . . . 8
4.2. DNS Updates . . . . . . . . . . . . . . . . . . . . . . . 9 4.2. DNS Updates . . . . . . . . . . . . . . . . . . . . . . . 9
4.3. Allocation strategies . . . . . . . . . . . . . . . . . . 9 4.3. Allocation strategies . . . . . . . . . . . . . . . . . . 9
5. Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 5. Attacks . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1. Device type discovery (fingerprinting) . . . . . . . . . 10 5.1. Device type discovery (fingerprinting) . . . . . . . . . 10
5.2. Operating system discovery (fingerprinting) . . . . . . . 11 5.2. Operating system discovery (fingerprinting) . . . . . . . 11
5.3. Finding location information . . . . . . . . . . . . . . 11 5.3. Finding location information . . . . . . . . . . . . . . 11
5.4. Finding previously visited networks . . . . . . . . . . . 11 5.4. Finding previously visited networks . . . . . . . . . . . 11
5.5. Finding a stable identity . . . . . . . . . . . . . . . . 11 5.5. Finding a stable identity . . . . . . . . . . . . . . . . 11
5.6. Pervasive monitoring . . . . . . . . . . . . . . . . . . 12 5.6. Pervasive monitoring . . . . . . . . . . . . . . . . . . 11
5.7. Finding client's IP address or hostname . . . . . . . . . 12 5.7. Finding client's IP address or hostname . . . . . . . . . 12
5.8. Correlation of activities over time . . . . . . . . . . . 12 5.8. Correlation of activities over time . . . . . . . . . . . 12
5.9. Location tracking . . . . . . . . . . . . . . . . . . . . 12 5.9. Location tracking . . . . . . . . . . . . . . . . . . . . 12
5.10. Leasequery & bulk leasequery . . . . . . . . . . . . . . 13 5.10. Leasequery & bulk leasequery . . . . . . . . . . . . . . 12
6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 13 7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 13
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 13
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1. Normative References . . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 14 10.2. Informative References . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction 1. Introduction
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its client-id stored in stable storage while other may its client-id stored in stable storage while other may
generate it on the fly and use a different one after each generate it on the fly and use a different one after each
boot. Stable identifier may or may not be globally unique. boot. Stable identifier may or may not be globally unique.
3. DHCPv6 options carrying identifiers 3. DHCPv6 options carrying identifiers
In DHCPv6, there are many options which include identification In DHCPv6, there are many options which include identification
information or can be used to extract the identification information information or can be used to extract the identification information
about the client. This section enumerates various options and about the client. This section enumerates various options and
identifiers conveyed in them, which can be used to disclose client identifiers conveyed in them, which can be used to disclose client
identification. identification. The attacks that are enabled by such disclosures are
detailed in Section 5.
3.1. DUID 3.1. DUID
Each DHCPv6 client and server has a DHCPv6 Unique Identifier (DUID) Each DHCPv6 client and server has a DHCPv6 Unique Identifier (DUID)
[RFC3315]. The DUID is designed to be unique across all DHCPv6 [RFC3315]. The DUID is designed to be unique across all DHCPv6
clients and servers, and to remain stable after it has been initially clients and servers, and to remain stable after it has been initially
generated. The DUID can be of different forms. Commonly used forms generated. The DUID can be of different forms. Commonly used forms
are based on the link-layer address of one of the device's network are based on the link-layer address of one of the device's network
interfaces (with or without a timestamp), on the Universally Unique interfaces (with or without a timestamp), on the Universally Unique
IDentifier (UUID) [RFC6355]. The default type, defined in IDentifier (UUID) [RFC6355]. The default type, defined in
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Client System Architecture Type option, or by using fingerprinting Client System Architecture Type option, or by using fingerprinting
techniques on the combination of options requested using the Option techniques on the combination of options requested using the Option
Request option. See Section 3.4 of Request option. See Section 3.4 of
[I-D.ietf-6man-ipv6-address-generation-privacy] for a discussion [I-D.ietf-6man-ipv6-address-generation-privacy] for a discussion
about this type of attack. about this type of attack.
5.3. Finding location information 5.3. Finding location information
The location information can be obtained by the attacker by many The location information can be obtained by the attacker by many
means. The most direct way to obtain this information is by looking means. The most direct way to obtain this information is by looking
into a message originating from the server server that contains the into a message originating from the server that contains the Civic
Civic Location or GeoLoc option. It can also be indirectly inferred Location or GeoLoc option. It can also be indirectly inferred using
using the Remote ID Option, the Interface ID option (e.g. if an the Remote ID Option, the Interface ID option (e.g. if an access
access circuit on an Access Node corresponds to a civic location), or circuit on an Access Node corresponds to a civic location), or the
the Subscriber ID Option (if the attacker has access to subscriber Subscriber ID Option (if the attacker has access to subscriber info).
info).
5.4. Finding previously visited networks 5.4. Finding previously visited networks
When DHCPv6 clients connect to a network, they attempt to obtain the When DHCPv6 clients connect to a network, they attempt to obtain the
same address they had used before they attached to the network. They same address they had used before they attached to the network. They
do this by putting the previously assigned address(es) in the IA do this by putting the previously assigned address(es) in the IA
Address Option(s). [RFC3315] does not exclude IA_TA in such a case, Address Option(s). [RFC3315] does not exclude IA_TA in such a case,
so it is possible that a client implementation includes an address so it is possible that a client implementation includes an address
contained in an IA_TA for the Confirm message. By observing these contained in an IA_TA for the Confirm message. By observing these
addresses, an attacker can identify the network the client had addresses, an attacker can identify the network the client had
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can send ICMPv6 echo requests or other probe packets to networks of can send ICMPv6 echo requests or other probe packets to networks of
suspected client locations) can be used. To give specific example, suspected client locations) can be used. To give specific example,
by accessing a social portal from tomek- by accessing a social portal from tomek-
laptop.coffee.somecity.com.example, tomek- laptop.coffee.somecity.com.example, tomek-
laptop.mycompany.com.example and tomek-laptop.myisp.example.com, the laptop.mycompany.com.example and tomek-laptop.myisp.example.com, the
portal administrator can draw conclusions about tomek-laptop's owner portal administrator can draw conclusions about tomek-laptop's owner
current location and his habits. current location and his habits.
5.10. Leasequery & bulk leasequery 5.10. Leasequery & bulk leasequery
Attackers may pretend as an access concentrator, either DHCPv6 relay Attackers may masquerade as an access concentrator, either DHCPv6
agent or DHCPv6 client, to obtain location information directly from relay agent or DHCPv6 client, to obtain location information directly
the DHCP server(s) using the DHCPv6 Leasequery [RFC5007] mechanism. from the DHCP server(s) using the DHCPv6 Leasequery [RFC5007]
mechanism.
Location information is information needed by the access concentrator Location information is information needed by the access concentrator
to forward traffic to a broadband-accessible host. This information to forward traffic to a broadband-accessible host. This information
includes knowledge of the host hardware address, the port or virtual includes knowledge of the host hardware address, the port or virtual
circuit that leads to the host, and/or the hardware address of the circuit that leads to the host, and/or the hardware address of the
intervening subscriber modem. intervening subscriber modem.
Furthermore, the attackers may use DHCPv6 bulk leasequery [RFC5460] Furthermore, the attackers may use DHCPv6 bulk leasequery [RFC5460]
mechanism to obtain bulk information about DHCPv6 bindings, even mechanism to obtain bulk information about DHCPv6 bindings, even
without knowing the target bindings. without knowing the target bindings.
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DHCPv6. As such, no dedicated discussion is needed. DHCPv6. As such, no dedicated discussion is needed.
8. IANA Considerations 8. IANA Considerations
This draft does not request any IANA action. This draft does not request any IANA action.
9. Acknowledgements 9. Acknowledgements
The authors would like to thank Stephen Farrell, Ted Lemon, Ines The authors would like to thank Stephen Farrell, Ted Lemon, Ines
Robles, Russ White, Christian Schaefer, Jinmei Tatuya, Bernie Volz, Robles, Russ White, Christian Schaefer, Jinmei Tatuya, Bernie Volz,
Marcin Siodelski, Christian Huitema and other members of DHC WG for Marcin Siodelski, Christian Huitema, Brian Haberman and other members
their valuable comments. of DHC WG for their valuable comments.
This document was produced using the xml2rfc tool [RFC2629]. This document was produced using the xml2rfc tool [RFC2629].
10. References 10. References
10.1. Normative References 10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
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