Customer Edge Router Identification Option
draft-donley-dhc-cer-id-option-03
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Expired".
|
|
|---|---|---|---|
| Authors | Chris Donley , Michael Kloberdans , John Jason Brzozowski , Chris Grundemann | ||
| Last updated | 2014-02-14 | ||
| RFC stream | (None) | ||
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| Consensus boilerplate | Unknown | ||
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| IESG | IESG state | I-D Exists | |
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draft-donley-dhc-cer-id-option-03
Network Working Group C. Donley
Internet-Draft M. Kloberdans
Intended status: Informational CableLabs
Expires: August 18, 2014 J. Brzozowski
Comcast
C. Grundemann
ISOC
February 14, 2014
Customer Edge Router Identification Option
draft-donley-dhc-cer-id-option-03
Abstract
Addressing mechanisms supporting DHCPv6 Prefix Delegation in home
networks such as those described in CableLabs' eRouter specification
and the HIPnet Internet-Draft require identification of the customer
edge router (CER) as the demarcation between the customer network and
the service provider network. This document reserves a DHCPv6 option
to identify the CER.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on August 18, 2014.
Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. CER Identification Option . . . . . . . . . . . . . . . . . . 2
3. Authentication . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Null Authentication . . . . . . . . . . . . . . . . . . . 4
3.2. Simple Password Authentication . . . . . . . . . . . . . 4
3.3. Cryptographic Authentication . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.1. Normative References . . . . . . . . . . . . . . . . . . 6
7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
Some addressing mechanisms supporting DHCPv6 Prefix Delegation in
home networks such as those described in [I-D.grundemann-hipnet] and
[EROUTER] require identification of the customer edge router as the
demarcation between the customer network and the service provider
network. For prefix delegation purposes, it is desirable for other
routers within the home to know which device is the CER so that the
customer nome network only requests a single prefix from the ISP
DHCPv6 server, and efficiently distributes this prefix within the
home. This document reserves a DHCPv6 option to be used to identify
the CER.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. CER Identification Option
A Customer Edge Router (CER) sets the CER_ID to the IPv6 address of
its LAN interface. If it has more than one LAN IPv6 address, it
selects one of its LAN or loopback IPv6 addresses to be used in the
CER_ID. An ISP server does not respond with the CER_ID or sets the
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CER_ID to ::. Such a response or lack of response indicates to the
DHCPv6 client that it is the CER.
The format of the CER Identification option is:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| reserved | Auth type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Authentication |
| |
| | |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| CER_ID |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CER_ID (TBD).
option-len 36
reserved 16-bit set to 0
Auth Type see section 3
Authentication see section 3
CER_ID value IPv6 address of CER or ::
Figure 1.
A DHCPv6 client SHOULD include the CER Identification option code in
an Option Request option [RFC3315] in its DHCP Solicit messages.
The DHCPv6 server MAY include the CER Identification option in any
response it sends to a client that has included the CER
Identification option code in an Option Request option. The CER
Identification option is sent in the main body of the message to
client, not as a sub-option in, e.g., an IA_NA, IA_TA
[RFC3315]option.
When sending the CER Identification option, the DHCPv6 server MUST
set the CER_ID value to either one of its IPv6 addresses or ::. If a
device does not receive the CER Identification Option or receives a
CER ID of :: from the DHCPv6 server, it MUST include one of its
Globally Unique IPv6 address(es) in the CER_ID value in response to
DHCPv6 messages received by its DHCPv6 server that contains the CER
Identification option code in an Option Request option. If the
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device has only one LAN interface, it SHOULD use its LAN IPv6 address
as the CER_ID value. If the device has more than one LAN interface,
it SHOULD use the lowest Globally Unique address not assigned to its
WAN interface.
3. Authentication
All CER-ID messages are authenticated. The CER-ID option header
includes an authentication type field, and 128 bits of data for use
by the appropriate authentication scheme (determined by the type
field).
The authentication type is configurable on a per-DHCP-scope basis.
Additional authentication data is also configurable on a per-scope
basis.
Authentication types 0, 1 and 2 are defined by this document. All
other authentication types are reserved for definition by the IANA
(iana@ISI.EDU). The current list of authentication types is
described below.
Authentication Type | Description
-------------------------------+--------------------------------
0 Null Authentication
1 Simple Password
2 Cryptographic authentication
All Others Reserved for assignment by IANA
Authentication Type Description
___________________________________________ 0 Null authentication 1
Simple password 2 Cryptographic authentication All others Reserved
for assignment by the IANA (iana@ISI.EDU) D.1 Null authentication D.2
Simple password authentication D.3 Cryptographic authentication
3.1. Null Authentication
Use of this authentication type means that the CER-ID option exchange
is not authenticated. The 128-bit authentication field in the option
header can contain anything; it is not examined on packet reception.
3.2. Simple Password Authentication
Using this authentication type, a 128-bit field is configured on a
per-network basis. All packets sent by DHCP servers on a particular
home network will have this configured value in their CER-ID option
128-bit authentication field. This essentially serves as a "clear"
128-bit password. Simple password authentication guards against home
routers inadvertently joining the home IP network (HIPnet); each
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router must first be configured with its attached networks' passwords
before it can participate in the hipnet (e.g., by extending trust to
the CER for prefix delegation, service discovery, and firewall
services). However, simple password authentication is vulnerable to
passive attacks widespread on the Internet. Anyone with physical
access to the network can learn the password and compromise the
security of the hipnet.
3.3. Cryptographic Authentication
Using this authentication type, a shared secret key is configured in
all routers within the hipnet. For each CER-ID option, the key is
used to generate/verify a MD5 "message digest" that is inserted into
the authentication field. The message digest is a one-way function
of the 128-bit CER ID and the secret key. Since the secret key is
never sent over the network in the clear, protection is provided
against passive attacks.
4. IANA Considerations
IANA is requested to assign an option code from the "DHCP Option
Codes" Registry for OPTION_CER_ID. IANA is also requested to
maintain a list of authentication options.
5. Security Considerations
The security of a home network is an important consideration. Both
the HIPNet [I-D.grundemann-hipnet] and Homenet
[I-D.ietf-homenet-arch] approaches change the operational model of
the home network vs. today's IPv4-only paradigm. Specifically, these
networks eliminate NAT inside the home network (and only enable it
for IPv4 at the edge router, if required), support global
addressability of devices, and thus need to consider firewall and/or
filter support in various home routers. As the security profile of
these home routers can shift based on their position in the network
(e.g., edge vs. internal), security can be severely compromised if
routers misidentify their border and mistakenly reduce or eliminate
firewall rules. If the CER-ID option is used as part of the border
detection algorithm, a malicious actor with network access to a home
router could trick the router into lowering its security perimeter by
providing DHCP prefix delegation and adding its address in the CER-ID
option. However, this risk could be mitigated by adding simple
password authentication or cryptographic authentication. However, as
home router devices auto-provision out of the box, and are often not
configured directly by customers, the possibility exists that these
routers come pre-configured for null authentication, which lessens
the security. This is equivalent to routing protocol options such as
RIP(v2) or OSPF, which can be run with comparable authentication
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options and often default to null authentication. Customers
interested in security should ensure that they enable stronger
authentication during initial provisioning.
6. Acknowledgements
7. References
7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003.
7.2. Informative References
[EROUTER] CableLabs, "CableLabs IPv4 and IPv6 eRouter Specification
(CM-SP-eRouter-I11-131120)", November 2013.
[I-D.grundemann-hipnet]
Grundemann, C., Donley, C., Brzozowski, J., Howard, L.,
and V. Kuarsingh, "A Near Term Solution for Home IP
Networking (HIPnet)", draft-grundemann-hipnet-00 (work in
progress), July 2013.
[I-D.ietf-homenet-arch]
Chown, T., Arkko, J., Brandt, A., Troan, O., and J. Weil,
"IPv6 Home Networking Architecture Principles", draft-
ietf-homenet-arch-11 (work in progress), October 2013.
Authors' Addresses
Chris Donley
CableLabs
858 Coal Creek Cir.
Louisville, CO 80027
US
Email: c.donley@cablelabs.com
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Michael Kloberdans
CableLabs
858 Coal Creek Cir
Louisville, CO 80027
US
Email: m.kloberdans@cablelabs.com
John Brzozowski
Comcast
1306 Goshen Parkway
West Chester, PA 19380
US
Email: john_brzozowski@cable.comcast.com
Chris Grundemann
ISOC
Denver CO
Email: cgrundemann@gmail.com
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