draft-ietf-dhc-dhcpv6-opt-netboot-03.txt   draft-ietf-dhc-dhcpv6-opt-netboot-04.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: August 8, 2009 Development GmbH Expires: October 16, 2009 Development GmbH
V. Zimmer V. Zimmer
Intel Intel
D. Thaler D. Thaler
Microsoft Microsoft
February 4, 2009 April 14, 2009
DHCPv6 option for network boot DHCPv6 option for network boot
draft-ietf-dhc-dhcpv6-opt-netboot-03 draft-ietf-dhc-dhcpv6-opt-netboot-04
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (c) 2009 IETF Trust and the persons identified as the Copyright (c) 2009 IETF Trust and the persons identified as the
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to this document.
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 are
required for booting a node from the network. required for booting a node from the network.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3
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 . . . . . . . . . . . . . . . 5 3.2. Boot File Parameters Option . . . . . . . . . . . . . . . 5
3.3. Client System Architecture Type Option . . . . . . . . . . 6 3.3. Client System Architecture Type Option . . . . . . . . . . 6
3.4. Client Network Interface Identifier Option . . . . . . . . 6 3.4. Client Network Interface Identifier Option . . . . . . . . 6
4. Appearance of the options . . . . . . . . . . . . . . . . . . 7 4. Appearance of the options . . . . . . . . . . . . . . . . . . 7
5. Boot protocol considerations . . . . . . . . . . . . . . . . . 7 5. Download protocol considerations . . . . . . . . . . . . . . . 7
6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8
7. Security considerations . . . . . . . . . . . . . . . . . . . 9 7. Security considerations . . . . . . . . . . . . . . . . . . . 9
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 . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
Network booting means that a node which should be booted fetches the Network booting means that a node which should be booted fetches the
files required for booting via its network device from a server. files required for booting via its network device from a server.
Network booting is, for example, very useful in environments where Network booting is, for example, very useful in environments where
the administrators have to maintain a large number of nodes. Since the administrators have to maintain a large number of nodes. Since
all boot and configuration files are stored on a central server, the all boot and configuration files are stored on a central server, the
maintenance of all nodes can be kept simple this way. maintenance of all nodes can be kept simple this way.
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 (BIOS) running on the client node must perform the following
two steps (see Figure 1): First get all information which are two steps (see Figure 1): First get all information which are
required for downloading and executing the boot file such as: the required for downloading and executing the boot file such as: the
server on which the boot files can be found, the protocol to be used server on which the boot files can be found, the protocol to be used
for the download (for example TFTP [RFC1350]), the name of the boot for the download (for example HTTP [RFC2616] or TFTP [RFC1350]), the
file and additional parameters which should be passed to the OS name of the boot file and additional parameters which should be
kernel or boot loader program respectively. As second step, download passed to the OS kernel or boot loader program respectively. As
the boot file from the file server and execute it. second step, download the boot file from the file server 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|
+------+ +------+
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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 RFC 3315 [RFC3315].
3. Options 3. Options
As specified in the DHCPv6 RFC [RFC3315], all values in the options
are in network byte order. Options are byte-aligned but are not
aligned in any other way such as on 2 or 4 byte boundaries. There is
no padding between the options.
3.1. Boot File Uniform Resource Locator (URL) Option 3.1. Boot File Uniform Resource Locator (URL) Option
This option consists of an ASCII string. It is used to convey an URL This option consists of an ASCII string. It is used to convey an URL
to a boot file. to a 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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Option defined for DHCPv4 in [RFC4578] section 2.1. Option defined for DHCPv4 in [RFC4578] section 2.1.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_CLIENT_ARCH_TYPE | option-len | | OPTION_CLIENT_ARCH_TYPE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. Processor Architecture Type (variable length) . . Architecture Type (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_CLIENT_ARCH_TYPE (TBD3). option-code OPTION_CLIENT_ARCH_TYPE (TBD3).
option-len See below. FIXME option-len Length of the "processor architecture type" field
in octets (not including the option-code and
option-len fields). It MUST be an even number
greater than zero. See [RFC4578] section 2.1 for
details.
Processor Architecture Type A list of one or more architecture Architecture Type A list of one or more architecture types, as
types, as specified in [RFC4578] section 2.1. specified in [RFC4578] section 2.1.
3.4. Client Network Interface Identifier Option 3.4. Client Network Interface Identifier Option
The Client Network Interface Identifier option is sent by a DHCP The Client Network Interface Identifier option is sent by a DHCP
client to a DHCP server to provide information about its level of client to a DHCP server to provide information about its level of
Universal Network Device Interface (UNDI) support (see also [PXE21] Universal Network Device Interface (UNDI) support (see also [PXE21]
and [UEFI22]). and [UEFI22]).
This option provides parity with the Client Network Interface This option provides parity with the Client Network Interface
Identifier Option defined for DHCPv4 in [RFC4578] section 2.2. Identifier Option defined for DHCPv4 in [RFC4578] section 2.2.
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4. Appearance of the options 4. Appearance of the options
These options MUST NOT appear in DHCPv6 messages other than the types These options MUST NOT appear in DHCPv6 messages other than the types
Solicit, Advertise, Request, Renew, Rebind, Information-Request and Solicit, Advertise, Request, Renew, Rebind, Information-Request and
Reply. Reply.
The option-codes of these options MAY appear in the Option Request The option-codes of these options MAY appear in the Option Request
Option in the DHCPv6 message types Solicit, Request, Renew, Rebind, Option in the DHCPv6 message types Solicit, Request, Renew, Rebind,
Information-Request and Reconfigure. Information-Request and Reconfigure.
5. Boot protocol considerations 5. Download protocol considerations
RFC 906 [RFC906] suggests to use TFTP for bootstrap loading. Since Depending on the network infrastructure, various special requirements
could be imposed on the download protocol, so this document does not
force one protocol for all scenarios. However, in case there there
are no special requirements, the HTTP protocol SHOULD be used as
download protocol.
RFC 906 [RFC906] suggested to use TFTP for bootstrap loading. Since
TFTP is based on UDP, it has the advantage that it can also be used TFTP is based on UDP, it has the advantage that it can also be used
in firmware implementations which have to deal with size and in firmware implementations which have to deal with size and
complexity constraints and thus can not include a full-blown TCP/IP complexity constraints and thus can not include a full-blown TCP/IP
stack. It can also be used in multicast mode (see [RFC2090]) which stack. It can also be used in multicast mode (see [RFC2090]) which
is useful when a lot of nodes boot the same boot file at the same is useful when a lot of nodes boot the same boot file at the same
time. So if TFTP should be used as boot protocol, the boot file URLs time. So if TFTP should be used as download protocol, the boot file
then must be specified according to RFC 3617 [RFC3617]. URLs then must be specified according to RFC 3617 [RFC3617].
However, TFTP also has some severe limitations, for example However, TFTP also has some severe limitations, for example
performance limitations due to acknowledging each packet and size performance limitations due to acknowledging each packet and size
limitations due to using only 16-bit packet counters. So this limitations due to using only 16-bit packet counters. So this
specification suggests to use now the well-known and established specification suggests to use now the well-known and established
hypertext transfer protocol (HTTP, see [RFC2616]) as default for hypertext transfer protocol (HTTP, see [RFC2616]) as default for
network booting instead. network booting instead. If a secure download is required, it is
also possible to use HTTP with TLS (HTTPS, see [RFC2818]).
An alternative approach to network booting is to bootstrap the system An alternative approach to network booting is to bootstrap the system
with iSCSI. In this case, the URL in the OPT_BOOTFILE_URL option with iSCSI. In this case, the URL in the OPT_BOOTFILE_URL option
MUST be specified according to the "iscsi:" string definition in MUST be specified according to the "iscsi:" string definition in
chapter 5 of [RFC4173]. Note that [RFC4173] also suggests that the chapter 5 of [RFC4173]. Note that [RFC4173] also suggests that the
"iscsi:" string should be specified in the so-called "Root Path" "iscsi:" string should be specified in the so-called "Root Path"
option. However, this option does not exist for DHCPv6 yet, and with option. However, this option does not exist for DHCPv6 yet, and with
the OPT_BOOTFILE_URL it is also not necessary anymore. So for IPv6 the OPT_BOOTFILE_URL it is also not necessary anymore. So for IPv6
iSCSI booting, the "iscsi:" string MUST be specified as URL in the iSCSI booting, the "iscsi:" string MUST be specified as URL in the
OPT_BOOTFILE_URL option instead. OPT_BOOTFILE_URL option instead.
If multiple interfaces are available for booting, it might be a good If multiple interfaces are available for booting, it might be a good
strategy to send out requests out on each interface in parallel to strategy to send out requests on each interface in parallel to speed
speed up the discovery. However how to handle multiple replies, i.e. up the discovery. However how to handle multiple replies, i.e.
replies from more than one DHCP server is not a problem that can be replies from more than one DHCP server is not a problem that can be
easily solved on the protocol level. It is up to the implementors to easily solved on the protocol level. It is up to the implementors to
provide users with a possibility to either choose a network interface provide users with a possibility to either choose a network interface
to boot from, or to assign a preference to interfaces or even known to boot from, or to assign a preference to interfaces or even known
DHCP servers. DHCP servers.
6. IANA considerations 6. IANA considerations
The following options needs to be assigned by the IANA from the The following options need to be assigned by the IANA from the option
option number space defined in the chapter 22 of the DHCPv6 RFC number space defined in the chapter 22 of the DHCPv6 RFC [RFC3315].
[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 |
+-------------------------+-------+--------------+ +-------------------------+-------+--------------+
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Architecture Type". Registry entries consist of a 16-bit integer Architecture Type". Registry entries consist of a 16-bit integer
recorded in decimal format, and a descriptive name. The initial recorded in decimal format, and a descriptive name. The initial
values of this registry can be found in [RFC4578] section 2.1. values of this registry can be found in [RFC4578] section 2.1.
The assignment policy for values shall be Expert Review (see The assignment policy for values shall be Expert Review (see
[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
The new DHCPv6 option described in this document could be sent in The new DHCPv6 options described in this document could be sent in
untrusted networks by malicious people with a fake DHCPv6 server to untrusted networks by malicious people with a fake DHCPv6 server to
confuse the booting clients. The clients could be provided with a confuse the booting clients. The clients could be provided with a
wrong URL so that the boot either fails, or even worse, the client wrong URL so that the boot either fails, or even worse, the client
boots the wrong operating system which has been provided by a boots the wrong operating system which has been provided by a
malicious file server. To prevent this kind of attack, clients malicious file server. To prevent this kind of attack, clients
SHOULD use authentication of DHCPv6 messages (see chapter 21. in SHOULD use authentication of DHCPv6 messages (see chapter 21. in
[RFC3315]). [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.
skipping to change at page 10, line 39 skipping to change at page 10, line 47
[RFC1350] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33, [RFC1350] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33,
RFC 1350, July 1992. RFC 1350, July 1992.
[RFC2090] Emberson, A., "TFTP Multicast Option", RFC 2090, [RFC2090] Emberson, A., "TFTP Multicast Option", RFC 2090,
February 1997. February 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, May 2000.
[RFC906] Finlayson, R., "Bootstrap Loading using TFTP", RFC 906, [RFC906] Finlayson, R., "Bootstrap Loading using TFTP", RFC 906,
June 1984. June 1984.
Authors' Addresses Authors' Addresses
Thomas H. Huth Thomas H. Huth
IBM Germany Research & Development GmbH IBM Germany Research & Development GmbH
Schoenaicher Strasse 220 Schoenaicher Strasse 220
Boeblingen 71032 Boeblingen 71032
Germany Germany
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