draft-ietf-dhc-dhcpv6-opt-netboot-02.txt   draft-ietf-dhc-dhcpv6-opt-netboot-03.txt 
DHC T. Huth DHC T. Huth
Internet-Draft J. Freimann Internet-Draft J. Freimann
Intended status: Standards Track IBM Deutschland Research & Intended status: Standards Track IBM Germany Research &
Expires: May 22, 2009 Development GmbH Expires: August 8, 2009 Development GmbH
November 18, 2008 V. Zimmer
Intel
D. Thaler
Microsoft
February 4, 2009
DHCPv6 option for network boot DHCPv6 option for network boot
draft-ietf-dhc-dhcpv6-opt-netboot-02 draft-ietf-dhc-dhcpv6-opt-netboot-03
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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 a new option for DHCPv6 to convey network. This document describes new options for DHCPv6 which are
information, required for network booting, to the nodes. 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. Netboot option format . . . . . . . . . . . . . . . . . . . . 3 3. Options . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Suboptions . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3.1. Boot File Uniform Resource Locator (URL) Option . . . . . 4
4.1. Suboption: Boot file Uniform Resource Locator (URL) . . . 4 3.2. Boot File Parameters Option . . . . . . . . . . . . . . . 5
4.2. Suboption: Vendor class extension . . . . . . . . . . . . 6 3.3. Client System Architecture Type Option . . . . . . . . . . 6
5. Appearance of the Netboot option . . . . . . . . . . . . . . . 7 3.4. Client Network Interface Identifier Option . . . . . . . . 6
6. Boot protocol considerations . . . . . . . . . . . . . . . . . 8 4. Appearance of the options . . . . . . . . . . . . . . . . . . 7
7. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8 5. Boot protocol considerations . . . . . . . . . . . . . . . . . 7
8. Security considerations . . . . . . . . . . . . . . . . . . . 9 6. IANA considerations . . . . . . . . . . . . . . . . . . . . . 8
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 7. Security considerations . . . . . . . . . . . . . . . . . . . 9
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9
10.1. Normative References . . . . . . . . . . . . . . . . . . . 9 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
10.2. Informative References . . . . . . . . . . . . . . . . . . 10 9.1. Normative References . . . . . . . . . . . . . . . . . . . 9
9.2. Informative References . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
Intellectual Property and Copyright Statements . . . . . . . . . . 12
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 download 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 be provided with firmware (BIOS) running on the client node must perform the following
information such as: the server on which the boot files can be found, two steps (see Figure 1): First get all information which are
the protocol to be used for the download (for example TFTP [RFC1350]) required for downloading and executing the boot file such as: the
and the name of the boot file. Since some kernels or boot loaders server on which the boot files can be found, the protocol to be used
need to be provided with additional parameters, there should also be for the download (for example TFTP [RFC1350]), the name of the boot
the possibility to pass additional parameters along with the server file and additional parameters which should be passed to the OS
address, the protocol and the file name. kernel or boot loader program respectively. As second step, download
the boot file from the file server and execute it.
+------+
_______________________\| DHCP |
/ 1 Get boot file info /|Server|
+------+ +------+
| Host |
+------+ +------+
\_______________________\| File |
2 Download boot file /|Server|
+------+
Figure 1: Network Boot Sequence
DHCPv6 allows client nodes to ask a DHCPv6 server for configuration DHCPv6 allows client nodes to ask a DHCPv6 server for configuration
parameters. Contrary to its IPv4 predecessor, DHCPv6 does not yet parameters. Contrary to its IPv4 predecessor, DHCPv6 does not yet
define a way to query network boot options such as the IPv6 address define a way to query network boot options such as the IPv6 address
of a boot file server and boot file names. Therefore this document of a boot file server and boot file names. Therefore this document
defines a new DHCPv6 option which is required for network booting defines new DHCPv6 options which are required for network booting
clients. clients.
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 RFC 3315 [RFC3315].
3. Netboot option format 3. Options
The netboot option is used as an encapsulation for suboptions which 3.1. Boot File Uniform Resource Locator (URL) Option
carry the actual information needed to boot a client. This option
will be used by clients to request boot information from a server. This option consists of an ASCII string. It is used to convey an URL
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_NET_BOOT | option-len | | OPT_BOOTFILE_URL | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| suboption-code 1 | suboption-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subopt-data 1 (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. <multiple suboptions> . . bootfile-url (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| suboption-code n | suboption-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| subopt-data n (variable length) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPT_NET_BOOT (TBD1). Format description:
option-len Length of the netboot option in octets (not option-code OPT_BOOTFILE_URL (TBD1).
option-len Length of the bootfile URL option in octets (not
including the size of the option-code and option- including the size of the option-code and option-
len fields). len fields).
suboption-code, suboption-len and subopt-data together comprise a bootfile-url This ASCII string is the URL (conforming to
suboption for the netboot option. The 16-bit [RFC3986]) for a boot file. This string starts
unsigned suboption-code values are drawn from a with the protocol which is used for downloading.
private namespace of the netboot option managed by Separated by "://", the hostname or IPv6 address of
IANA (cf. Section 8). The 16-bit unsigned the server hosting the boot file follows, and then
suboption-len values indicate the length of the the path, file name and query parts of the URL.
subopt-data field in octets. The string is not null-terminated.
Multiple occurences of each suboption-type can occur within a netboot
option (for example when more than one boot server is available).
Clients MUST process the suboptions in the order in which they appear
in the message sent by the server.
So far, only the suboptions in the following chapters have been Note about the bootfile-url: This string can either contain a
defined. Other suboptions might be defined in future RFCs. hostname or a literal IPv6 address to specify the server where the
boot file should be downloaded from. All clients which implement the
OPT_BOOTFILE_URL option MUST be able to handle IPv6 addresses here
and SHOULD also be able to handle a hostname in the URL. The IPv6
address in the URL then MUST be enclosed in "[" and "]" characters,
conforming to [RFC3986]. Clients SHOULD also be able to handle
hostnames in the URLs. However, in this case the firmware
implementation on the client machine must support DNS, too. Due to
size limitations, this might not be possible in all firmware
implementations, so support for hostnames in the URLs is only
optional.
4. Suboptions Multiple occurrences of OPT_BOOTFILE_URL can be present in a single
DHCP message. Clients MUST process them in the order in which they
appear within the message. The client starts with the first file
that should be downloaded and executed. In case of a failure the
process should continue with the second one and so on.
4.1. Suboption: Boot file Uniform Resource Locator (URL) 3.2. Boot File Parameters Option
This suboption consists of multiple ASCII strings. It is used to This option consists of multiple ASCII strings. They are used to
convey an URL to a boot file together with additional parameters for specify parameters for the boot file (e.g. parameters for the kernel
the boot file (e.g. parameters for the kernel or boot loader or boot loader program).
program).
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUBOPT_BOOTFILE_URL | suboption-len | | OPT_BOOTFILE_PARAM | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| bootfile-len | bootfile-url |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (variable length) .
. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| param-len 1 | parameter 1 | | param-len 1 | parameter 1 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (variable length) . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (variable length) .
. | . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. <multiple Parameters> . . <multiple Parameters> .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| param-len n | parameter n | | param-len n | parameter n |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (variable length) . +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ (variable length) .
. | . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format description: Format description:
suboption-code SUBOPT_BOOTFILE_URL (1). option-code OPT_BOOTFILE_PARAM (TBD2).
suboption-len Length of the bootfile suboption in octets (not
including the size of the suboption-code and
suboption-len fields).
bootfile-len 16-bit integer that specifies the length of the
bootfile-url in octets (not including the bootfile-
length field).
bootfile-url This ASCII string is the URL (conforming to option-len Length of the bootfile parameters option in octets
[RFC3986]) for a boot file. This string starts (not including the size of the option-code and
with the protocol which is used for downloading. option-len fields).
Separated by "://", the hostname or IPv6 address of
the server hosting the boot file (see also the note
below) follows, and then the path, file name and
query parts of the URL. The string is not null-
terminated.
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).
parameters 1...n These ASCII strings are parameters needed for parameters 1...n These ASCII strings are parameters needed for
booting, e.g. kernel parameters. The strings are booting, e.g. kernel parameters. The strings are
not null-terminated. The firmware should pass not null-terminated.
these parameters in the order they appear in the
SUBOPT_BOOTFILE_URL suboption to the boot file
which has been specified in the bootfile-url field.
In cases where no parameters are needed, everything
but the boot file URL (including its length field)
can be omitted.
Note about the bootfile-url: This string can either contain a
hostname or a literal IPv6 address to specify the server where the
boot file should be downloaded from. All clients which implement the
SUBOPT_BOOTFILE_URL suboption MUST be able to handle IPv6 addresses
here and SHOULD also be able to handle a hostname in the URL. The
IPv6 address in the URL then MUST be enclosed in "[" and "]"
characters, conforming to [RFC3986]. Clients SHOULD also be able to
handle hostnames in the URLs. However, in this case the firmware
implementation on the client machine must support DNS, too. Due to
size limitations, this might not be possible in all firmware
implementations, so support for hostnames in the URLs is only
optional.
Since multiple occurrences of SUBOPT_BOOTFILE_URL can be present in a The firmware MUST pass these parameters in the order they appear in
single OPT_NETBOOT message, clients MUST process them in the order in the OPT_BOOTFILE_PARAM option to the boot file which has been
which they appear within the message. For example in the case of a specified in the OPT_BOOTFILE_URL option.
boot file URL the first file should be downloaded and executed. In
case of a failure the process should continue with the second one and
so on.
4.2. Suboption: Vendor class extension 3.3. Client System Architecture Type Option
With this suboption, vendors can define their own netboot suboptions: This option provides parity with the Client System Architecture Type
It can be used by clients and servers to exchange vendor-specific Option defined for DHCPv4 in [RFC4578] section 2.1.
information which is related to network booting.
This suboption can occur multiple times within a OPT_NET_BOOT option The format of the option is:
(also with different enterprise-numbers in case a server and client
implementation supports different vendor extensions). Clients MUST
process them in the order in which they appear within the message.
Unsupported vendor extensions MUST be ignored.
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SUBOPT_NETBOOT_VENDOR | suboption-len | | OPTION_CLIENT_ARCH_TYPE | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| enterprise-number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
. . . .
. vendor-class-data . . Processor Architecture Type (variable length) .
. (variable length) .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Format description: option-code OPTION_CLIENT_ARCH_TYPE (TBD3).
suboption-code SUBOPT_NETBOOT_VENDOR (2). option-len See below. FIXME
suboption-len Length of the vendor class suboption in octets Processor Architecture Type A list of one or more architecture
(not including the size of the suboption-code and types, as specified in [RFC4578] section 2.1.
suboption-len fields).
enterprise-number The enterprise number of the vendor as registered 3.4. Client Network Interface Identifier Option
with IANA (see [VENDORIDS]).
vendor-class-data Vendor-specific information. The meaning is The Client Network Interface Identifier option is sent by a DHCP
defined by the vendor identified by the client to a DHCP server to provide information about its level of
enterprise-number. It is suggested that the Universal Network Device Interface (UNDI) support (see also [PXE21]
vendor-class-data SHOULD be composed of a series and [UEFI22]).
of separate items with a two-octets length field
at the beginning of each item, as it is described
for the vendor class option in chapter 22.16 of
[RFC3315].
5. Appearance of the Netboot option This option provides parity with the Client Network Interface
Identifier Option defined for DHCPv4 in [RFC4578] section 2.2.
The netboot option MUST NOT appear in DHCPv6 messages other than the The format of the option is:
types Solicit, Advertise, Request, Renew, Rebind, Information-Request
and Reply.
The option-code of the netboot option MAY appear in the Option 0 1 2 3
Request Option in the DHCPv6 message types Solicit, Request, Renew, 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
Rebind, Information-Request and Reconfigure. +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_NII | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Major | Minor |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The suboptions MUST appear only in the netboot option. option-code OPTION_NII (TBD4).
6. Boot protocol considerations option-len 3
RFC 906 [RFC906] suggests to use TFTP for bootstrap loading. Because Type As specified in [RFC4578] section 2.2.
it is easy to implement this protocol in firmware (where one has to
deal with size and complexity constraints), this is still the
recommended protocol for network booting. Every firmware
implementation SHOULD at least support this protocol. The boot file
URLs then must be specified according to RFC 3617 [RFC3617].
An alternative approach to TFTP network booting is to bootstrap the Major As specified in [RFC4578] section 2.2.
system with iSCSI. In this case, the URL in the SUBOPT_BOOTFILE_URL
suboption MUST be specified according to the "iscsi:" string
definition in chapter 5 of [RFC4173]. Note that [RFC4173] also
suggests that the "iscsi:" string should be specified in the so-
called "Root Path" option. However, this option does not exist for
DHCPv6 yet, and with the SUBOPT_BOOTFILE_URL it is also not necessary
anymore. So for IPv6 iSCSI booting, the "iscsi:" string MUST be
specified as URL in the SUBOPT_BOOTFILE_URL suboption instead.
In some different scenarios, it might also be useful to use other Minor As specified in [RFC4578] section 2.2.
protocols like FTP or HTTP for network booting, so a firmware
implementation can support these protocols, too. Then it is up to
the network administrator to choose the appropriate boot protocol for
the network, and to specify the right boot file URLs in the DHCPv6
server configuration file.
7. IANA considerations 4. Appearance of the options
The following option needs to be assigned by the IANA from the option These options MUST NOT appear in DHCPv6 messages other than the types
number space defined in the chapter 22 of the DHCPv6 RFC [RFC3315]. Solicit, Advertise, Request, Renew, Rebind, Information-Request and
Reply.
+--------------+-------+--------------+ The option-codes of these options MAY appear in the Option Request
Option in the DHCPv6 message types Solicit, Request, Renew, Rebind,
Information-Request and Reconfigure.
5. Boot protocol considerations
RFC 906 [RFC906] suggests to use TFTP for bootstrap loading. Since
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
complexity constraints and thus can not include a full-blown TCP/IP
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
time. So if TFTP should be used as boot protocol, the boot file URLs
then must be specified according to RFC 3617 [RFC3617].
However, TFTP also has some severe limitations, for example
performance limitations due to acknowledging each packet and size
limitations due to using only 16-bit packet counters. So this
specification suggests to use now the well-known and established
hypertext transfer protocol (HTTP, see [RFC2616]) as default for
network booting instead.
An alternative approach to network booting is to bootstrap the system
with iSCSI. In this case, the URL in the OPT_BOOTFILE_URL option
MUST be specified according to the "iscsi:" string definition in
chapter 5 of [RFC4173]. Note that [RFC4173] also suggests that the
"iscsi:" string should be specified in the so-called "Root Path"
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
iSCSI booting, the "iscsi:" string MUST be specified as URL in the
OPT_BOOTFILE_URL option instead.
If multiple interfaces are available for booting, it might be a good
strategy to send out requests out on each interface in parallel to
speed 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
easily solved on the protocol level. It is up to the implementors to
provide users with a possibility to either choose a network interface
to boot from, or to assign a preference to interfaces or even known
DHCP servers.
6. IANA considerations
The following options needs to be assigned by the IANA from the
option number space defined in the chapter 22 of the DHCPv6 RFC
[RFC3315].
+-------------------------+-------+--------------+
| Option name | Value | Specified in | | Option name | Value | Specified in |
+--------------+-------+--------------+ +-------------------------+-------+--------------+
| OPT_NET_BOOT | TBD1 | Section 3 | | OPT_BOOTFILE_URL | TBD1 | Section 3.1 |
+--------------+-------+--------------+ | OPT_BOOTFILE_PARAM | TBD2 | Section 3.2 |
| OPTION_CLIENT_ARCH_TYPE | TBD3 | Section 3.3 |
| OPTION_NII | TBD4 | Section 3.4 |
+-------------------------+-------+--------------+
The OPT_NET_BOOT option also defines a new 16-bit integer suboption This document also introduces a new IANA registry for processor
field, for which IANA is to create and maintain a new sub-registry architecture types. The name of this registry shall be "Processor
entitled "Netboot Suboptions" under the OPT_NET_BOOT option. Initial Architecture Type". Registry entries consist of a 16-bit integer
values for the Netboot Suboptions registry are given below; future recorded in decimal format, and a descriptive name. The initial
assignments are to be made through IETF Review (see [RFC5226]). values of this registry can be found in [RFC4578] section 2.1.
Assignments consist of a suboption name and its associated value.
+-----------------------+-------+--------------+ The assignment policy for values shall be Expert Review (see
| Suboption name | Value | Specified in | [RFC5226]), and any requests for values must supply the descriptive
+-----------------------+-------+--------------+ name for the processor architecture type.
| SUBOPT_BOOTFILE_URL | 1 | Section 4.1 |
| SUBOPT_NETBOOT_VENDOR | 2 | Section 4.2 |
+-----------------------+-------+--------------+
8. Security considerations 7. Security considerations
The new DHCPv6 option described in this document could be sent in The new DHCPv6 option 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 RFC SHOULD use authentication of DHCPv6 messages (see chapter 21. in
3315 [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.
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.
9. Acknowledgements 8. Acknowledgements
The authors would like to thank Ketan P. Pancholi and Alfred Hoenes The authors would like to thank Ruth Li, Dong Wei, Kathryn Hampton,
for corrections and suggestions. Phil Dorah, Richard Chan, and Fiona Jensen for discussions that led
to this document.
Vijayabhaskar Kalusivalingam and Senthil Balasubramanian published a The authors would also like to thank Ketan P. Pancholi and Alfred
similar draft for IPv6 network booting some years ago (available at Hoenes for corrections and suggestions.
http://tools.ietf.org/html/draft-ietf-dhc-dhcpv6-opt-rboot-00), which
however was abandoned for unknown reasons.
10. References 9. References
10.1. Normative References 9.1. Normative References
[PXE21] Johnston, M., "Preboot Execution Environment (PXE)
Specification", September 1999,
<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.
[RFC3617] Lear, E., "Uniform Resource Identifier (URI) Scheme and [RFC3617] Lear, E., "Uniform Resource Identifier (URI) Scheme and
Applicability Statement for the Trivial File Transfer Applicability Statement for the Trivial File Transfer
skipping to change at page 10, line 20 skipping to change at page 10, line 15
[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
Protocol (DHCP) Options for the Intel Preboot eXecution
Environment (PXE)", RFC 4578, November 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[VENDORIDS] [UEFI22] UEFI Forum, "Unified Extensible Firmware Interface
IANA, "Private Enterprise Numbers", Specification, Version 2.2", September 2008,
<http://www.iana.org/assignments/enterprise-numbers>. <http://www.uefi.org/>.
10.2. Informative References 9.2. Informative References
[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,
February 1997.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[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 Deutschland Research & Development GmbH IBM Germany Research & Development GmbH
Schoenaicher Strasse 220 Schoenaicher Strasse 220
Boeblingen 71032 Boeblingen 71032
Germany Germany
Phone: +49-7031-16-2183 Phone: +49-7031-16-2183
Email: thuth@de.ibm.com Email: thuth@de.ibm.com
Jens T. Freimann Jens T. Freimann
IBM Deutschland Research & Development GmbH IBM Germany Research & Development GmbH
Schoenaicher Strasse 220 Schoenaicher Strasse 220
Boeblingen 71032 Boeblingen 71032
Germany Germany
Phone: +49-7031-16-1122 Phone: +49-7031-16-1122
Email: jfrei@de.ibm.com Email: jfrei@de.ibm.com
Full Copyright Statement Vincent Zimmer
Intel
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