draft-ietf-dhc-pxe-options-02.txt   draft-ietf-dhc-pxe-options-03.txt 
Dynamic Host Configuration Working M. Johnston Dynamic Host Configuration Working M. Johnston
Group Intel Corporation Group Intel Corporation
Internet-Draft S. Venaas, Ed. Internet-Draft S. Venaas, Ed.
Expires: April 29, 2006 University of Southampton Expires: September 8, 2006 UNINETT
October 26, 2005 March 7, 2006
DHCP Preboot eXecution Environment (PXE) Options DHCP Options for the Intel Preboot eXecution Environment (PXE)
draft-ietf-dhc-pxe-options-02 draft-ietf-dhc-pxe-options-03
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
Abstract Abstract
We define DHCP options being used by PXE and EFI clients to uniquely We define DHCP options being used by Preboot eXecution Environment
(PXE) and Extensible Firmware Interface (EFI) clients to uniquely
identify booting client machines and their pre-OS runtime environment identify booting client machines and their pre-OS runtime environment
so the DHCP and/or PXE boot server can return the correct OS so the DHCP and/or PXE boot server can return the correct OS
bootstrap image (or pre-boot application) name and server to the bootstrap image (or pre-boot application) name and server to the
client. client.
Requirements Language Requirements Language
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 [1]. document are to be interpreted as described in RFC 2119 [1].
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Revision history . . . . . . . . . . . . . . . . . . . . . . . 3 2. Option Definitions . . . . . . . . . . . . . . . . . . . . . . 3
3. Option Definitions . . . . . . . . . . . . . . . . . . . . . . 4 2.1. Client System Architecture Type Option Definition . . . . . 3
3.1. Client System Architecture Type Option Definition . . . . . 4 2.2. Client Network Interface Identifier Option Definition . . . 4
3.2. Client Network Interface Identifier Option Definition . . . 4 2.3. Client Machine Identifier Option Definition . . . . . . . . 5
3.3. Client Machine Identifier Option Definition . . . . . . . . 5 2.4. Options Requested by PXE Clients . . . . . . . . . . . . . 5
3.4. Options Requested by PXE Clients . . . . . . . . . . . . . 5 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5
4. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 6 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 6 5. Security Considerations . . . . . . . . . . . . . . . . . . . . 6
6. Security Considerations . . . . . . . . . . . . . . . . . . . . 6 6. Normative References . . . . . . . . . . . . . . . . . . . . . 6
7. Normative References . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 8 Intellectual Property and Copyright Statements . . . . . . . . . . 8
1. Introduction 1. Introduction
These DHCP [2] options are being widely used by PXE compliant clients These DHCP [2] options are being widely used by PXE compliant clients
to uniquely identify booting client machines themselves and their to uniquely identify booting client machines themselves and their
pre-OS runtime environment so the DHCP and/or PXE boot server can pre-OS runtime environment so the DHCP and/or PXE boot server can
return the correct OS bootstrap image (or pre-boot application) name return the correct OS bootstrap image (or pre-boot application) name
and server to the client. In the past, this work was done by and server to the client. In the past, this work was done by
examining the network MAC address in the "chaddr" field in the BOOTP/ examining the network MAC address in the "chaddr" field in the BOOTP/
DHCP header and keeping a database of MAC addresses on the BOOTP/DHCP DHCP header and keeping a database of MAC addresses on the BOOTP/DHCP
server. This was deemed insufficient for large and complex networks server. This was deemed insufficient for large and complex networks
for two main reasons. 1) Multiple laptops could end up with the same for two main reasons. 1) Multiple laptops could end up with the same
MAC address if the NIC was in a shared docking station. 2) Multiple MAC address if the NIC was in a shared docking station. 2) Multiple
network devices and MAC addresses could be used by one machine for network devices and MAC addresses could be used by one machine for
redundancy or because of repairs. Another issue that came up was the redundancy or because of repairs. Another issue that came up was the
machine that could change its pre-OS runtime environment. This issue machine that could change its pre-OS runtime environment. This issue
caused the creation of another new option to identify the runtime caused the creation of another new option to identify the runtime
environment so the correct binary image could be matched up with the environment so the correct binary image could be matched up with the
booting machine. These options are defined in the PXE [3] and EFI booting machine. These options are defined by Intel in the PXE [3]
[4] specifications and are being documented in this draft for and EFI [4] specifications and are being documented in this draft for
completeness within the IETF. Comments about this Internet Draft completeness within the IETF.
should be sent to the dhcwg@ietf.org mailing list.
2. Revision history
Revision 00 to Revision 01
o Changed all occurrences of "suboption" to "option".
o Re-worded first sentence of Introduction to clarify that these
options are in wide use by PXE clients.
o Clarified external document references.
o Added description of use of options 128 through 135.
o Added IANA Considerations and Security Considerations sections.
Revision 01 to Revision 02
o Changed and extended description of use of options 128 through
135.
o Removed text on IANA registries since Informational.
3. Option Definitions 2. Option Definitions
There are three DHCP options [5] defined for use by PXE clients. There are three DHCP options [5] defined for use by PXE clients.
3.1. Client System Architecture Type Option Definition 2.1. Client System Architecture Type Option Definition
The format of the option is: The format of the option is:
Code Len 16-bit Type Code Len 16-bit Type
+----+-----+-----+-----+ +----+-----+-----+-----+
| 93 | n | n1 | n2 | | 93 | n | n1 | n2 |
+----+-----+-----+-----+ +----+-----+-----+-----+
Octet "n" MUST be an even number greater than zero. Clients that Octet "n" gives the number of octets containing "architecture types"
support more than one architecture type MAY include a list of these (not including the code and len fields). It MUST be an even number
types in their initial DHCP and PXE boot server packets. The list of greater than zero. Clients that support more than one architecture
supported architecture types MAY be reduced in any packet exchange type MAY include a list of these types in their initial DHCP and PXE
between the client and server(s). Octets "n1" and "n2" encode a 16- boot server packets. The list of supported architecture types MAY be
bit architecture type identifier that describes the pre-boot runtime reduced in any packet exchange between the client and server(s).
environment(s) of the client machine. Octets "n1" and "n2" encode a 16-bit architecture type identifier
that describes the pre-boot runtime environment(s) of the client
machine.
As of the writing of this document the following pre-boot As of the writing of this document the following pre-boot
architecture types have been requested. architecture types have been requested.
Type Architecture Name Type Architecture Name
---- ----------------- ---- -----------------
0 Intel x86PC 0 Intel x86PC
1 NEC/PC98 1 NEC/PC98
2 EFI Itanium 2 EFI Itanium
3 DEC Alpha 3 DEC Alpha
4 Arc x86 4 Arc x86
5 Intel Lean Client 5 Intel Lean Client
6 EFI IA32 6 EFI IA32
This option MUST be present in all DHCP and PXE packets sent by PXE This option MUST be present in all DHCP and PXE packets sent by PXE
compliant clients and servers. compliant clients and servers.
3.2. Client Network Interface Identifier Option Definition 2.2. Client Network Interface Identifier Option Definition
The format of the option is: The format of the option is:
Code Len Type Major Minor Code Len Type Major Minor
+----+-----+----+-----+-----+ +----+-----+----+-----+-----+
| 94 | 3 | t | M | m | | 94 | 3 | t | M | m |
+----+-----+----+-----+-----+ +----+-----+----+-----+-----+
Octet "t" encodes a network interface type. For now the only Octet "t" encodes a network interface type. For now the only
supported value is 1 for UNDI (Universal Network Device Interface). supported value is 1 for UNDI (Universal Network Device Interface).
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3.10 32/64-bit UNDI specification. (Beta) [4] 3.10 32/64-bit UNDI specification. (Beta) [4]
First generation EFI runtime driver support. First generation EFI runtime driver support.
3.20 32/64-bit UNDI specification. (Release) [4] 3.20 32/64-bit UNDI specification. (Release) [4]
Second generation EFI runtime driver support. Second generation EFI runtime driver support.
This option MUST be present in all DHCP and PXE packets sent by PXE This option MUST be present in all DHCP and PXE packets sent by PXE
compliant clients and servers. compliant clients and servers.
3.3. Client Machine Identifier Option Definition 2.3. Client Machine Identifier Option Definition
The format of the option is: The format of the option is:
Code Len Type Machine Identifier Code Len Type Machine Identifier
+----+-----+----+-----+ . . . +-----+ +----+-----+----+-----+ . . . +-----+
| 97 | n | t | | . . . | | | 97 | n | t | | . . . | |
+----+-----+----+-----+ . . . +-----+ +----+-----+----+-----+ . . . +-----+
Octet "t" describes the type of the machine identifier in the Octet "t" describes the type of the machine identifier in the
remaining octets in this option. 0 (zero) is the only defined value remaining octets in this option. 0 (zero) is the only defined value
for this octet at the present time and it describes the remaining for this octet at the present time and it describes the remaining
octets as a 16-octet GUID. Octet "n" is 17 for type 0. (One octets as a 16-octet GUID. Octet "n" is 17 for type 0. (One
definition of GUID can be found in Appendix A in the EFI definition of GUID can be found in Appendix A in the EFI
specification [efi].) specification [efi].)
This option MUST be present in all DHCP and PXE packets sent by PXE This option MUST be present in all DHCP and PXE packets sent by PXE
compliant clients and servers. compliant clients and servers.
3.4. Options Requested by PXE Clients 2.4. Options Requested by PXE Clients
All compliant PXE clients MUST include a request for DHCP options 128 All compliant PXE clients MUST include a request for DHCP options 128
through 135 in all DHCP and PXE packets. The format and contents of through 135 in all DHCP and PXE packets. The format and contents of
these options are NOT defined by the PXE specification. These these options are NOT defined by the PXE specification. These
options MAY be present in the DHCP and PXE boot server replies and options MAY be present in the DHCP and PXE boot server replies and
are meant for use by the downloaded network bootstrap programs. are meant for use by the downloaded network bootstrap programs.
These options are NOT used by the PXE boot ROMs. These options are NOT used by the PXE boot ROMs.
As options 128-135 are not officially assigned for PXE use (previous As options 128-135 are not officially assigned for PXE use (previous
to November 2004 they were considered site-specific options, [6]), to November 2004 they were considered site-specific options, [6]),
use of these options may conflict with other uses of these options. use of these option values for PXE may conflict with other uses of
the same options on the same networks.
4. Acknowledgements 3. Acknowledgements
The authors thank Bernie Volz for valuable input. The authors thank Bernie Volz for valuable input.
5. IANA Considerations 4. IANA Considerations
This document has no actions for IANA. IANA is requested to update the numbering space defined for public
DHCP options in [7] with references to this document for options 93,
94 and 97 (currently there are references to [8]), and also mark
options 128-135 as being used by PXE and reference this document
(they are currently marked as being used by PXE, but without
references).
6. Security Considerations 5. Security Considerations
This document in and by itself provides no security, nor does it By specifying incorrect values for some of these options a client may
impact existing security. get access to, and possibly attempt to execute, code intended for
another platform or client. This may have security ramifications.
Also note that these options contain information about a client's
system architecture and pre-OS runtime environment which is revealed
to anyone who is able to listen in on DHCP messages sent by the
client. This information may be of use to potential attackers.
7. Normative References 6. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[2] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, [2] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997. March 1997.
[3] Henry, M. and M. Johnston, "Preboot Execution Environment (PXE) [3] Henry, M. and M. Johnston, "Preboot Execution Environment (PXE)
Specification", September 1999, Specification", September 1999,
<http://www.pix.net/software/pxeboot/archive/pxespec.pdf>. <http://www.pix.net/software/pxeboot/archive/pxespec.pdf>.
skipping to change at page 7, line 5 skipping to change at page 6, line 39
[4] Intel Corp., "Extensible Firmware Interface Specification", [4] Intel Corp., "Extensible Firmware Interface Specification",
December 2002, <http://developer.intel.com/technology/efi/ December 2002, <http://developer.intel.com/technology/efi/
main_specification.htm>. main_specification.htm>.
[5] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor [5] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997. Extensions", RFC 2132, March 1997.
[6] Volz, B., "Reclassifying Dynamic Host Configuration Protocol [6] Volz, B., "Reclassifying Dynamic Host Configuration Protocol
version 4 (DHCPv4) Options", RFC 3942, November 2004. version 4 (DHCPv4) Options", RFC 3942, November 2004.
[7] Droms, R., "Procedures and IANA Guidelines for Definition of New
DHCP Options and Message Types", BCP 43, RFC 2939,
September 2000.
[8] Droms, R., "Unused Dynamic Host Configuration Protocol (DHCP)
Option Codes", RFC 3679, January 2004.
Authors' Addresses Authors' Addresses
Michael Johnston Michael Johnston
Intel Corporation Intel Corporation
MS. JF1-239 2111 NE 25th Ave. MS. JF1-239 2111 NE 25th Ave.
Hillsboro, OR 97124 Hillsboro, OR 97124
USA USA
Phone: +1 503-264-9703 Phone: +1 503-264-9703
Email: michael.johnston@intel.com Email: michael.johnston@intel.com
Stig Venaas Stig Venaas
University of Southampton UNINETT
School of Electronics and Computer Science Trondheim NO-7465
Southampton, Hampshire SO17 1BJ Norway
United Kingdom
Email: sv@ecs.soton.ac.uk Email: venaas@uninett.no
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WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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Copyright (C) The Internet Society (2005). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
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Internet Society. Internet Society.
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