Network Working Group Vijayabhaskar A Kalusivalingam
Internet-Draft Senthil K Balasubramanian
Expires: August 2004 Hewlett-Packard
Feb 2004
DHCPv6 Support for Remote Boot
draft-ietf-dhc-dhcpv6-opt-rboot-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2004). All Rights Reserved.
Abstract
This document provides new DHCPv6 (Dynamic Host Configuration
protocol version 6) options for clients, to obtain information about
FTP (Trivial File Transfer Protocol) servers and bootfiles needed
for booting.
1. Introduction
Network booting is widely used mechanism for booting up of the
clients. The clients contact the TFTP server to download the
bootfiles for bootup. The advantages of using network booting are;
softwares will be in central server and requires maintenance at only
one location rather than maintaining individual systems separately.
Also, switching between different operating systems becomes easy when
network booting is being used. In some cases, the nodes may need
multiple bootfiles also. The additional boot files may be used as
supporting software for the boot image. Different Operating System
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vendors use different way of handling this. Single TFTP server for
huge number of diskless clients is prone to single point of failure.
So, Multiple TFTP servers are needed for high availability.
DHCPv6 (Dynamic Host Configuration Protocol Version 6) provides a
framework for passing configuration information for hosts on an IPv6
network. However, DHCPv6 does not provide a way to send information
about TFTP server address and bootfile names. This document defines
two options, Remote boot option and Remote Boot parameter option to
provide information about TFTP servers and bootfile names to the
clients. These options are required for the clients, which are
booting over a network.
2. Requirements
The keywords MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL, when they appear in this
document, are to be interpreted as described in RFC 2119 [2]
3. Terminology
This document uses terminology specific to IPv6 and DHCPv6 as defined
in "Terminology" section of the DHCPv6 specification [1].
4. Remote Boot Option
The Remote Boot Option is used to carry the parameters needed for
remote boot of the DHCPv6 clients. Using the information provided by
this option, the DHCPv6 clients will bootp up. This will be mainly
used by the clients, which are booting using remote boot server.
The format of the Remote Boot Option is as shown below:
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_REMOTE_BOOT | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Remote-Boot-options .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_REMOTE_BOOT (tbd)
option-len: Length of the 'Remote-Boot-options' fields in octets;
Remote_Boot-options: Options associated with the Remote Boot Option.
The Remote Boot option encapsulates those options that are specific
to remote boot. This document defines one such option called
Remote Boot Parameters Option. Multiple Remote Boot Parameters
Options can appear in this option. This option is defined in the
Section 5.
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5. Remote Boot Parameters Option
The Remote Boot Parameters Option is used by the server to convey
the client about the TFTP Server IPv6 address and list of boot files
needed for booting of the clients. The clients are supposed to
contact the TFTP Server, obtain the boot files one by one and boot up
using these files.
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_REMOTE_BOOT_PARAMS | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| TFTP Server (IPv6 address) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
. Boot Files .
. .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code: OPTION_REMOTE_BOOT_PARAMS (tbd)
option-len: Length of the 'TFTP Server' (16 bytes) + 'Boot Files'
in Octets;
Boot Files: One or more Boot File names in the NVT-ASCII string
format. Each file name should be NULL terminated. They
should be represented as fully qualified directory-path name.
If multiple boot files are provided by the server, then, they should
appear in the order of their execution in the client. The first
appearing boot file name should be downloaded and executed first for
boot up, then the next and so on.
This option MUST appear only in the Remote Boot Option. If multiple
Remote Boot Parameters Options are present in the Remote Boot Option,
then the clients MUST treat them as an ordered list. The server MAY
list them in the order of preference.
6. Appearance of these options
The Remote Boot Option MUST NOT appear in other than the following
messages: Solicit, Advertise, Request, Renew, Rebind,
Information-Request and Reply.
The option number of Remote Boot option MAY appear in the Option
Request Option [1] in the following messages: Solicit, Request,
Renew, Rebind, Information-Request and Reconfigure.
The Remote Boot Parameters Option MUST appear only in the Remote
Boot Option.
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7. Security Considerations
The Remote Boot Option may be used by an intruder DHCPv6 server to
cause DHCPv6 clients to contact rogue TFTP server (or) to send
invalid file names. This will make booting up of DHCPv6 clients to
fail. This will have a greater impact, if the clients are running
some time critical applications. It has a direct impact on the
security of the networks, if the clients are running any security
applications.
To avoid attacks through this option, the DHCP client SHOULD use
authenticated DHCP (see section "Authentication of DHCP messages" in
the DHCPv6 specification [1]).
8. IANA Considerations
IANA is requested to assign an option code to the following options
from the option-code space defined in "DHCPv6 Options" section of the
DHCPv6 specification [1].
Option Name Value Described in
OPTION_REMOTE_BOOT tbd Section 4
OPTION_REMOTE_BOOT_PARAMS tbd Section 5
9. Normative References
[1] Bound, J., Carney, M., Perkins, C., Lemon, T., Volz, B. and R.
Droms (ed.), "Dynamic Host Configuration Protocol for IPv6
(DHCPv6)", RFC 3315, July 2003.
[2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
10. Informative References
[3] K. Sollins, The TFTP Protocol (Revision 2), RFC 1350, July 1992.
Authors' Addresses
Vijayabhaskar A Kalusivalingam
Hewlett-Packard STSD-I
29, Cunningham Road
Bangalore - 560052
India
Phone: +91-80-22053085
E-Mail: vijayak@india.hp.com
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Internet-Draft DHCPv6 support for Remote Boot Feb 2004
Senthil K Balasubramanian
Hewlett-Packard STSD-I
29, Cunningham Road
Bangalore - 560052
India
Phone: +91-80-22053103
E-Mail: ksenthil@india.hp.com
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