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Key Distribution Center (KDC) Server Address Sub-option for the Dynamic Host Configuration Protocol (DHCP) CableLabs Client Configuration (CCC) Option
RFC 3634

Document type: RFC - Proposed Standard (December 2003; No errata)
Document stream: IETF
Last updated: 2013-03-02
Other versions: plain text, pdf, html

IETF State: (None)
Consensus: Unknown
Document shepherd: No shepherd assigned

IESG State: RFC 3634 (Proposed Standard)
Responsible AD: Margaret Wasserman
Send notices to: No addresses provided

Network Working Group                                          K. Luehrs
Request for Comments: 3634                                     CableLabs
Category: Standards Track                                      R. Woundy
                                                           Comcast Cable
                                                           J. Bevilacqua
                                                              N. Davoust
                                                         YAS Corporation
                                                           December 2003

      Key Distribution Center (KDC) Server Address Sub-option for
            the Dynamic Host Configuration Protocol (DHCP)
              CableLabs Client Configuration (CCC) Option

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document defines a new sub-option for the CableLabs Client
   Configuration (CCC) Dynamic Host Configuration Protocol (DHCP) option
   code for conveying the network addresses of Key Distribution Center
   (KDC) servers.

1.  Introduction

   A CableLabs Client Configuration (CCC) Dynamic Host Configuration
   Protocol (DHCP) Option code providing the Key Distribution Center
   (KDC) server address will be needed for CableHome-compliant
   residential gateways configured to use Kerberos for authentication as
   the first step in establishing a secure SNMPv3 link between the
   Portal Service (PS) logical element [2,3] in residential gateways,
   and the SNMP entity in the cable operator's data network.

   The CCC DHCP option code will be used to address specific needs of
   CableLabs client devices during their configuration processes.  This
   document proposes a sub-option for the CCC DHCP option.

Luehrs, et al.              Standards Track                     [Page 1]
RFC 3634             KDC Server Address Sub-option         December 2003

   Configuration of a class of CableLabs client devices described in [2]
   and [3] will require a DHCP sub-option to provide the client with the
   network address of a KDC server in the cable operator's data network.

   The class of devices assumed in [2] and [3] is unlike the class of
   devices considered in [1], which perform a DNS lookup of the Kerberos
   Realm name to find the KDC server network address.

   This document proposes a sub-option of the CCC DHCP option code for
   use with CableLabs client devices.  The proposed sub-option encodes
   an identifier for the network address of each of one or more Key
   Distribution Center servers with which the CableLabs client device
   exchanges security information.

   The key words "MUST", "MUST NOT", "SHOULD", "SHOULD NOT" and "MAY" in
   this document are to be interpreted as described in BCP 14, RFC 2119
   [4].

2.  Key Distribution Center IP Address Sub-option

   CableHome specifications will specify the Key Distribution Center
   network address encoding as a sub-option of the CCC DHCP Option code.
   This field will be used to inform the client device of the network
   address of one or more Key Distribution Center servers.

   The encoding of the KDC Server Address sub-option will adhere to the
   format of an IPv4 address.  The minimum length for this option is 4
   octets, and the length MUST always be a multiple of 4.  If multiple
   KDC Servers are listed, they MUST be listed in decreasing order of
   priority.  The format of the KDC Server Address sub-option of the CCC
   option code is as shown below:

    SubOpt  Len      Address 1               Address 2
   +------+-----+-----+-----+-----+-----+-----+-----+--
   |  10  |  n  |  a1 |  a2 |  a3 |  a4 |  a1 |  a2 |  ...
   +------+-----+-----+-----+-----+-----+-----+-----+--

3.  Security Considerations

   This document relies upon the DHCP protocol [5] for authentication
   and security, i.e., it does not provide security in excess of what
   DHCP is (or will be) providing.  Potential exposures to attack in the
   DHCP protocol are discussed in section 7 of the DHCP protocol
   specification [5] and in Authentication for DHCP Messages [6].

   The CCC option can be used to misdirect network traffic by providing
   incorrect DHCP server addresses, incorrect provisioning server
   addresses, and incorrect Kerberos realm names to a CableLabs client

Luehrs, et al.              Standards Track                     [Page 2]

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