draft-ietf-dhc-dhcpv6-opt-netboot-08.txt   draft-ietf-dhc-dhcpv6-opt-netboot-09.txt 
DHC T. Huth DHC T. Huth
Internet-Draft J. Freimann Internet-Draft J. Freimann
Intended status: Standards Track IBM Germany Research & Intended status: Standards Track IBM Germany Research &
Expires: July 8, 2010 Development GmbH Expires: December 8, 2010 Development GmbH
V. Zimmer V. Zimmer
Intel Intel
D. Thaler D. Thaler
Microsoft Microsoft
January 4, 2010 June 6, 2010
DHCPv6 option for network boot DHCPv6 option for network boot
draft-ietf-dhc-dhcpv6-opt-netboot-08 draft-ietf-dhc-dhcpv6-opt-netboot-09
Abstract Abstract
The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) provides a The Dynamic Host Configuration Protocol for IPv6 (DHCPv6) provides a
framework for passing configuration information to nodes on a framework for passing configuration information to nodes on a
network. This document describes new options for DHCPv6 which are network. This document describes new options for DHCPv6 which SHOULD
required for booting a node from the network. be used for booting a node from the network.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
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This Internet-Draft will expire on July 8, 2010. This Internet-Draft will expire on December 8, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 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
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carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
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described in the BSD License. described in the BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Options . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Options . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Boot File Uniform Resource Locator (URL) Option . . . . . 4 3.1. Boot File Uniform Resource Locator (URL) Option . . . . . 4
3.2. Boot File Parameters Option . . . . . . . . . . . . . . . 4 3.2. Boot File Parameters Option . . . . . . . . . . . . . . . 5
3.3. Client System Architecture Type Option . . . . . . . . . . 5 3.3. Client System Architecture Type Option . . . . . . . . . . 6
3.4. Client Network Interface Identifier Option . . . . . . . . 6 3.4. Client Network Interface Identifier Option . . . . . . . . 7
4. Appearance of the options . . . . . . . . . . . . . . . . . . 7 4. Appearance of the options . . . . . . . . . . . . . . . . . . 7
5. Download protocol considerations . . . . . . . . . . . . . . . 7 5. Download protocol considerations . . . . . . . . . . . . . . . 7
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Security considerations . . . . . . . . . . . . . . . . . . . 8 7. Security considerations . . . . . . . . . . . . . . . . . . . 8
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
9.1. Normative References . . . . . . . . . . . . . . . . . . . 9 9.1. Normative References . . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . . 10 9.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
This draft describes DHCPv6 options that can be used to provide This draft describes DHCPv6 options that SHOULD be used to provide
configuration information for a node that must be booted using the configuration information for a node that must be booted using the
network, rather than from local storage. network, rather than from local storage.
Network booting is used, for example, in some environments where Network booting is used, for example, in some environments where
administrators have to maintain a large number of nodes. By serving administrators have to maintain a large number of nodes. By serving
all boot and configuration files from a central server, the effort all boot and configuration files from a central server, the effort
required to maintain these nodes is greatly reduced. required to maintain these nodes is greatly reduced.
A typical boot file would be, for example, an operating system kernel A typical boot file would be, for example, an operating system kernel
or a boot loader program. To be able to execute such a file, the or a boot loader program. To be able to execute such a file, the
firmware (BIOS) running on the client node must perform the following firmware running on the client node must perform the following two
two steps (see Figure 1): First get all information which is required steps (see Figure 1): First get all information which is required for
for downloading and executing the boot file. Second, download the downloading and executing the boot file. Second, download the boot
boot file and execute it. file and execute it.
+------+ +------+
_______________________\| DHCP | _______________________\| DHCP |
/ 1 Get boot file info /|Server| / 1 Get boot file info /|Server|
+------+ +------+ +------+ +------+
| Host | | Host |
+------+ +------+ +------+ +------+
\_______________________\| File | \_______________________\| File |
2 Download boot file /|Server| 2 Download boot file /|Server|
+------+ +------+
Figure 1: Network Boot Sequence Figure 1: Network Boot Sequence
Information that is required for booting over the network can include The information which is required for booting over the network MUST
information about the server on which the boot files can be found, include at least the details about the server on which the boot files
the protocol to be used for the download (for example HTTP [RFC2616] can be found, the protocol to be used for the download (for example
or TFTP [RFC1350]), the name of the boot file and additional HTTP [RFC2616] or TFTP [RFC1350]) and the path and name of the boot
parameters which should be passed to the OS kernel or boot loader file on the server. Additionally, the server and client MAY exchange
program respectively. information about the parameters which should be passed to the OS
kernel or boot loader program respectively, or information about the
supported boot environment.
DHCPv6 allows client nodes to ask a DHCPv6 server for configuration DHCPv6 allows client nodes to ask a DHCPv6 server for configuration
parameters. This document provides new options which a client can parameters. This document provides new options which a client can
request from the DHCPv6 server to satisfy its requirements for request from the DHCPv6 server to satisfy its requirements for
booting. booting. It also introduces a new IANA registry for processor
architecture types which are used by the OPTION_CLIENT_ARCH_TYPE
option (see Section 3.3).
2. Conventions 2. Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
Terminology specific to IPv6 and DHCPv6 are used in the same way as Terminology specific to IPv6 and DHCPv6 are used in the same way as
defined in the "Terminology" sections of RFC 3315 [RFC3315]. defined in the "Terminology" sections of [RFC3315].
3. Options 3. Options
Option formats comply with DHCPv6 options per [RFC3315] (section 6). Option formats comply with DHCPv6 options per [RFC3315] (section 6).
The boot-file-url option (see Section 3.1) is mandatory for booting,
all other options are optional.
3.1. Boot File Uniform Resource Locator (URL) Option 3.1. Boot File Uniform Resource Locator (URL) Option
The server sends this option to inform the client about an URL to a The server sends this option to inform the client about an URL to a
boot file. boot file.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPT_BOOTFILE_URL | option-len | | OPT_BOOTFILE_URL | option-len |
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Format description: Format description:
option-code OPT_BOOTFILE_URL (TBD1). option-code OPT_BOOTFILE_URL (TBD1).
option-len Length of the boot-file-url in octets. option-len Length of the boot-file-url in octets.
boot-file-url This string is the URL for the boot file. It MUST boot-file-url This string is the URL for the boot file. It MUST
comply with STD 66 [RFC3986]. The string is not comply with STD 66 [RFC3986]. The string is not
NUL-terminated. NUL-terminated.
If the URL is expressed using an IPv6 address rather than a domain If the host in the URL is expressed using an IPv6 address rather than
name, the address in the URL then MUST be enclosed in "[" and "]" a domain name, the address in the URL then MUST be enclosed in "["
characters, conforming to [RFC3986]. Clients that have DNS and "]" characters, conforming to [RFC3986]. Clients that have DNS
implementations should support the use of domain names in the URL. implementations SHOULD support the use of domain names in the URL.
3.2. Boot File Parameters Option 3.2. Boot File Parameters Option
This option is sent by the server to the client. It consists of This option is sent by the server to the client. It consists of
multiple UTF-8 strings. They are used to specify parameters for the multiple UTF-8 ([RFC3629]) strings. They are used to specify
boot file (similar to the command line arguments in most modern parameters for the boot file (similar to the command line arguments
operating systems). For example, these parameters could be used to in most modern operating systems). For example, these parameters
specify the root file system of the OS kernel, or where a second could be used to specify the root file system of the OS kernel, or
stage boot loader can download its configuration file from. where a second stage boot loader can download its configuration file
from.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPT_BOOTFILE_PARAM | option-len | | OPT_BOOTFILE_PARAM | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| param-len 1 | | | param-len 1 | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ parameter 1 . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ parameter 1 .
. (variable length) | . (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 5, line 42 skipping to change at page 5, line 51
param-len 1...n This is a 16-bit integer which specifies the length param-len 1...n This is a 16-bit integer which specifies the length
of the following parameter in octets (not including of the following parameter in octets (not including
the parameter-length field). the parameter-length field).
parameter 1...n These UTF-8 strings are parameters needed for parameter 1...n These UTF-8 strings are parameters needed for
booting, e.g. kernel parameters. The strings are booting, e.g. kernel parameters. The strings are
not NUL-terminated. not NUL-terminated.
When the boot firmware executes the boot file which has been When the boot firmware executes the boot file which has been
specified in the OPT_BOOTFILE_URL option, it MUST pass these specified in the OPT_BOOTFILE_URL option, it MUST pass these
parameters in the order that they appear in the OPT_BOOTFILE_PARAM parameters, if present, in the order that they appear in the
option. OPT_BOOTFILE_PARAM option.
3.3. Client System Architecture Type Option 3.3. Client System Architecture Type Option
This option provides parity with the Client System Architecture Type This option provides parity with the Client System Architecture Type
Option defined for DHCPv4 in section 2.1 of [RFC4578]. Option defined for DHCPv4 in section 2.1 of [RFC4578].
The format of the option is: The format of the option is:
0 1 2 3 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 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
skipping to change at page 6, line 29 skipping to change at page 6, line 37
zero. See section 2.1 of [RFC4578] for details. zero. See section 2.1 of [RFC4578] for details.
architecture-types A list of one or more architecture types, as architecture-types A list of one or more architecture types, as
specified in section 2.1 of [RFC4578]. Each specified in section 2.1 of [RFC4578]. Each
architecture type identifier in this list is a architecture type identifier in this list is a
16-bit value which describes the pre-boot runtime 16-bit value which describes the pre-boot runtime
environment of the client machine. A list of environment of the client machine. A list of
valid values is maintained by the IANA (see valid values is maintained by the IANA (see
Section 6). Section 6).
The client can use this option to send a list of supported The client MAY use this option to send a list of supported
architecture types to the server, so the server can decide which boot architecture types to the server, so the server can decide which boot
file should be provided to the client. If a client supports more file should be provided to the client. If a client supports more
than one pre-boot environment (for example both, 32-bit and 64-bit than one pre-boot environment (for example both, 32-bit and 64-bit
executables), the most preferred architecture type MUST be listed as executables), the most preferred architecture type MUST be listed as
first item, followed by the others with descending priority. first item, followed by the others with descending priority.
The server can use this option to inform the client about the pre- If the client used this option in the request, the server SHOULD this
boot environments which are supported by the boot file. The list option to inform the client about the pre-boot environments which are
MUST only contain architecture types which have initially been supported by the boot file. The list MUST only contain architecture
queried by the client. The items MUST also be listed in order of types which have initially been queried by the client. The items
descending priority. MUST also be listed in order of descending priority.
3.4. Client Network Interface Identifier Option 3.4. Client Network Interface Identifier Option
If the client supports the Universal Network Device Interface (UNDI) If the client supports the Universal Network Device Interface (UNDI)
(see [PXE21] and [UEFI23]), it may send the Client Network Interface (see [PXE21] and [UEFI23]), it may send the Client Network Interface
Identifier option to a DHCP server to provide information about its Identifier option to a DHCP server to provide information about its
level of UNDI support. level of UNDI support.
This option provides parity with the Client Network Interface This option provides parity with the Client Network Interface
Identifier Option defined for DHCPv4 in section 2.2 of [RFC4578]. Identifier Option defined for DHCPv4 in section 2.2 of [RFC4578].
skipping to change at page 8, line 8 skipping to change at page 8, line 19
that for IPv6, this supersedes [RFC906] which recommended to use TFTP that for IPv6, this supersedes [RFC906] which recommended to use TFTP
for downloading (see [RFC3617] for the 'tftp' URL definition). for downloading (see [RFC3617] for the 'tftp' URL definition).
When using iSCSI for booting, the 'iscsi' URI is formed as defined in When using iSCSI for booting, the 'iscsi' URI is formed as defined in
[RFC4173]. The functionality attributed in RFC4173 to a root path [RFC4173]. The functionality attributed in RFC4173 to a root path
option is provided for IPv6 by the Boot File URL option instead. option is provided for IPv6 by the Boot File URL option instead.
6. IANA considerations 6. IANA considerations
The following options need to be assigned by the IANA from the option The following options need to be assigned by the IANA from the option
number space defined in the chapter 22 of the DHCPv6 RFC [RFC3315]. number space defined in the chapter 24 of the DHCPv6 RFC [RFC3315].
+-------------------------+-------+--------------+ +-------------------------+-------+--------------+
| Option name | Value | Specified in | | Option name | Value | Specified in |
+-------------------------+-------+--------------+ +-------------------------+-------+--------------+
| OPT_BOOTFILE_URL | TBD1 | Section 3.1 | | OPT_BOOTFILE_URL | TBD1 | Section 3.1 |
| OPT_BOOTFILE_PARAM | TBD2 | Section 3.2 | | OPT_BOOTFILE_PARAM | TBD2 | Section 3.2 |
| OPTION_CLIENT_ARCH_TYPE | TBD3 | Section 3.3 | | OPTION_CLIENT_ARCH_TYPE | TBD3 | Section 3.3 |
| OPTION_NII | TBD4 | Section 3.4 | | OPTION_NII | TBD4 | Section 3.4 |
+-------------------------+-------+--------------+ +-------------------------+-------+--------------+
skipping to change at page 8, line 36 skipping to change at page 8, line 47
[RFC5226]), and any requests for values must supply the descriptive [RFC5226]), and any requests for values must supply the descriptive
name for the processor architecture type. name for the processor architecture type.
7. Security considerations 7. Security considerations
In untrusted networks, a rogue DHCPv6 server could send the new In untrusted networks, a rogue DHCPv6 server could send the new
DHCPv6 options described in this document. The booting clients could DHCPv6 options described in this document. The booting clients could
then be provided with a wrong URL so that the boot either fails, or then be provided with a wrong URL so that the boot either fails, or
even worse, the client boots the wrong operating system which has even worse, the client boots the wrong operating system which has
been provided by a malicious file server. To prevent this kind of been provided by a malicious file server. To prevent this kind of
attack, clients can use authentication of DHCPv6 messages (see attack, clients SHOULD use authentication of DHCPv6 messages (see
chapter 21. in [RFC3315]). chapter 21. in [RFC3315]).
Note also that DHCPv6 messages are sent unencrypted by default. So Note also that DHCPv6 messages are sent unencrypted by default. So
the boot file URL options are sent unencrypted over the network, too. the boot file URL options are sent unencrypted over the network, too.
This can become a security risk since the URLs can contain sensitive This can become a security risk since the URLs can contain sensitive
information like user names and passwords (for example a URL like information like user names and passwords (for example a URL like
"ftp://username:password@servername/path/file"). At the current "ftp://username:password@servername/path/file"). At the current
point in time, there is no possibility to send encrypted DHCPv6 point in time, there is no possibility to send encrypted DHCPv6
messages, so it is strongly recommended not to use sensitive messages, so it is strongly RECOMMENDED not to use sensitive
information in the URLs in untrusted networks. information in the URLs in untrusted networks (using passwords in
URLs is deprecated anyway according to [RFC3986]).
Even if the DHCPv6 transaction is secured, this does not protect Even if the DHCPv6 transaction is secured, this does not protect
against attacks on the boot file download channel. Consequently, we against attacks on the boot file download channel. Consequently, we
recommend that either a protocol like HTTPS (see [RFC2817] and recommend that either protocols like HTTPS [RFC2818] or TLS within
[RFC2818]) be used to prevent spoofing, or that the boot loader HTTP [RFC2817] are used to prevent spoofing, or that the boot loader
implementation implement a mechanism for signing boot images and a software implements a mechanism for signing boot images and a
configurable signing key in memory, so that if a malicious image is configurable signing key in memory, so that if a malicious image is
provided, it can be detected and rejected. provided, it can be detected and rejected.
8. Acknowledgements 8. Acknowledgements
The authors would like to thank Ruth Li, Dong Wei, Kathryn Hampton, The authors would like to thank Ruth Li, Dong Wei, Kathryn Hampton,
Phil Dorah, Richard Chan, and Fiona Jensen for discussions that led Phil Dorah, Richard Chan, and Fiona Jensen for discussions that led
to this document. to this document.
The authors would also like to thank Ketan P. Pancholi, Alfred The authors would also like to thank Ketan P. Pancholi, Alfred
skipping to change at page 9, line 33 skipping to change at page 9, line 48
Specification", September 1999, Specification", September 1999,
<http://www.pix.net/software/pxeboot/archive/pxespec.pdf>. <http://www.pix.net/software/pxeboot/archive/pxespec.pdf>.
[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, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, January 2005. RFC 3986, January 2005.
[RFC4173] Sarkar, P., Missimer, D., and C. Sapuntzakis, [RFC4173] Sarkar, P., Missimer, D., and C. Sapuntzakis,
"Bootstrapping Clients using the Internet Small Computer "Bootstrapping Clients using the Internet Small Computer
System Interface (iSCSI) Protocol", RFC 4173, System Interface (iSCSI) Protocol", RFC 4173,
September 2005. September 2005.
[RFC4578] Johnston, M. and S. Venaas, "Dynamic Host Configuration [RFC4578] Johnston, M. and S. Venaas, "Dynamic Host Configuration
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