aboutsummaryrefslogtreecommitdiffstats
path: root/doc
diff options
context:
space:
mode:
authorH. Peter Anvin <hpa@zytor.com>2008-01-09 19:07:30 -0800
committerH. Peter Anvin <hpa@zytor.com>2008-01-09 19:07:30 -0800
commit1febc7936ec9c3f139d6ed993d4ec13b63c81f80 (patch)
tree2f974290cedb1337f1fadd03794bc0bd09968d78 /doc
parentf87662aa975e26d876920846244b202fb3a165e5 (diff)
parentaa850da5d3b9b8e0fedbe03e635503d4b8eecfa4 (diff)
downloadsyslinux-elf-1febc7936ec9c3f139d6ed993d4ec13b63c81f80.tar.gz
syslinux-elf-1febc7936ec9c3f139d6ed993d4ec13b63c81f80.tar.xz
syslinux-elf-1febc7936ec9c3f139d6ed993d4ec13b63c81f80.zip
Merge commit 'origin/master' into adv
Diffstat (limited to 'doc')
-rw-r--r--doc/rfc5071.txt787
1 files changed, 787 insertions, 0 deletions
diff --git a/doc/rfc5071.txt b/doc/rfc5071.txt
new file mode 100644
index 00000000..68f6f5a8
--- /dev/null
+++ b/doc/rfc5071.txt
@@ -0,0 +1,787 @@
+
+
+
+
+
+
+Network Working Group D. Hankins
+Request for Comments: 5071 ISC
+Category: Informational December 2007
+
+
+ Dynamic Host Configuration Protocol Options Used by PXELINUX
+
+Status of This Memo
+
+ This memo provides information for the Internet community. It does
+ not specify an Internet standard of any kind. Distribution of this
+ memo is unlimited.
+
+Abstract
+
+ This document describes the use by PXELINUX of some DHCP Option Codes
+ numbering from 208-211.
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 1]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+Table of Contents
+
+ 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
+ 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
+ 3. MAGIC Option . . . . . . . . . . . . . . . . . . . . . . . . . 4
+ 3.1. Description . . . . . . . . . . . . . . . . . . . . . . . 4
+ 3.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . 5
+ 3.3. Applicability . . . . . . . . . . . . . . . . . . . . . . 5
+ 3.4. Response to RFC 3942 . . . . . . . . . . . . . . . . . . . 5
+ 4. Configuration File Option . . . . . . . . . . . . . . . . . . 5
+ 4.1. Description . . . . . . . . . . . . . . . . . . . . . . . 5
+ 4.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . 6
+ 4.3. Applicability . . . . . . . . . . . . . . . . . . . . . . 6
+ 4.4. Response to RFC 3942 . . . . . . . . . . . . . . . . . . . 6
+ 4.5. Client and Server Behaviour . . . . . . . . . . . . . . . 6
+ 5. Path Prefix Option . . . . . . . . . . . . . . . . . . . . . . 7
+ 5.1. Description . . . . . . . . . . . . . . . . . . . . . . . 7
+ 5.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . 7
+ 5.3. Applicability . . . . . . . . . . . . . . . . . . . . . . 7
+ 5.4. Response to RFC 3942 . . . . . . . . . . . . . . . . . . . 8
+ 5.5. Client and Server Behaviour . . . . . . . . . . . . . . . 8
+ 6. Reboot Time Option . . . . . . . . . . . . . . . . . . . . . . 9
+ 6.1. Description . . . . . . . . . . . . . . . . . . . . . . . 9
+ 6.2. Packet Format . . . . . . . . . . . . . . . . . . . . . . 9
+ 6.3. Applicability . . . . . . . . . . . . . . . . . . . . . . 10
+ 6.4. Response to RFC 3942 . . . . . . . . . . . . . . . . . . . 10
+ 6.5. Client and Server Behaviour . . . . . . . . . . . . . . . 10
+ 7. Specification Conformance . . . . . . . . . . . . . . . . . . 11
+ 8. Security Considerations . . . . . . . . . . . . . . . . . . . 11
+ 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
+ 10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12
+ 11. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
+ 11.1. Normative References . . . . . . . . . . . . . . . . . . . 12
+ 11.2. Informative References . . . . . . . . . . . . . . . . . . 12
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 2]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+1. Introduction
+
+ PXE, the Preboot eXecution Environment, is a first-stage network
+ bootstrap agent. PXE is loaded out of firmware on the client host,
+ and performs DHCP [3] queries to obtain an IP address.
+
+ Once on the network, it loads a second-stage bootstrap agent as
+ configured by DHCP header and option contents.
+
+ PXELINUX is one such second-stage bootstrap agent. Once PXE has
+ passed execution to it, PXELINUX seeks its configuration from a cache
+ of DHCP options supplied to the PXE first-stage agent, and then takes
+ action based upon those options.
+
+ Most frequently, this implies loading via Trivial File Transfer
+ Protocol (TFTP) [6] one or more images that are decompressed into
+ memory, then executed to pass execution to the final Host Operating
+ System.
+
+ PXELINUX uses DHCP options 208-211 to govern parts of this bootstrap
+ process, but these options are not requested by the PXE DHCP client
+ at the time it acquires its lease. At that time, the PXE bootloader
+ has no knowledge that PXELINUX is going to be in use, and even so,
+ would have no way to know what option(s) PXELINUX might digest.
+ Local installations that serve this PXELINUX image to its clients
+ must also configure their DHCP servers to provide these options even
+ though they are not on the DHCP Parameter Request List [4].
+
+ These options are:
+
+ o "MAGIC" - 208 - An option whose presence and content verifies to
+ the PXELINUX bootloader that the options numbered 209-211 are for
+ the purpose as described herein.
+
+ o "ConfigFile" - 209 - Configures the path/filename component of the
+ configuration file's location, which this bootloader should use to
+ configure itself.
+
+ o "PathPrefix" - 210 - Configures a value to be prepended to the
+ ConfigFile to discern the directory location of the file.
+
+ o "RebootTime" - 211 - Configures a timeout after which the
+ bootstrap program will reboot the system (most likely returning it
+ to PXE).
+
+ Historically, these option codes numbering from 208-211 were
+ designated 'Site Local', but after publication of RFC3942 [8], they
+ were made available for allocation as new standard DHCP options.
+
+
+
+Hankins Informational [Page 3]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+ This document marks these codes as assigned.
+
+ This direct assignment of option code values in the option
+ definitions below is unusual as it is not mentioned in DHCP Option
+ Code assignment guidelines [5]. This document's Option Code
+ assignments are done within RFC 3942's provisions for documenting
+ prior use of option codes within the new range (128-223 inclusive).
+
+2. Terminology
+
+ o "first-stage bootloader" - Although a given bootloading order may
+ have many stages, such as where a BIOS boots a DOS Boot Disk,
+ which then loads a PXE executable, it is, in this example, only
+ the PXE executable that this document describes as the "first-
+ stage bootloader" -- in essence, this is the first stage of
+ booting at which DHCP is involved.
+
+ o "second-stage bootloader" - This describes a program loaded by the
+ first-stage bootloader at the behest of the DHCP server.
+
+ o "bootloader" and "network bootstrap agent" - These are synonyms,
+ excepting that "bootloader" is intentionally vague in that its
+ next form of bootstrapping may not in fact involve network
+ resources.
+
+ The key words "MAY", "MUST", "MUST NOT", "SHOULD", and "SHOULD NOT"
+ in this document are to be interpreted as described in RFC 2119 [2].
+
+3. MAGIC Option
+
+3.1. Description
+
+ If this option is provided to the PXE bootloader, then the value is
+ checked by PXELINUX to match the octet string f1:00:74:7e. If this
+ matches, then PXELINUX bootloaders will also consume options 209-211,
+ as described below. Otherwise, they are ignored.
+
+ This measure was intended to ensure that, as the 'Site Local' option
+ space is not allocated from a central authority, no conflict would
+ result in a PXELINUX bootloader improperly digesting options intended
+ for another purpose.
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 4]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+3.2. Packet Format
+
+ The MAGIC Option format is as follows:
+
+ Code Length m1 m2 m3 m4
+ +--------+--------+--------+--------+--------+--------+
+ | 208 | 4 | 0xF1 | 0x00 | 0x74 | 0x7E |
+ +--------+--------+--------+--------+--------+--------+
+
+ The code for this option is 208. The length is always four.
+
+3.3. Applicability
+
+ This option is absolutely inapplicable to any other purpose.
+
+3.4. Response to RFC 3942
+
+ The option code 208 will be adopted for this purpose and immediately
+ deprecated. Future standards action may return this option to an
+ available status should it be necessary.
+
+ A collision of the use of this option is harmless (at least from
+ PXELINUX' point of view) by design: if it does not match the
+ aforementioned magic value, the PXELINUX bootloader will take no
+ special action.
+
+ The PXELINUX project will deprecate the use of this option; future
+ versions of the software will not evaluate its contents.
+
+ It is reasonable to utilize this option code for another purpose, but
+ it is recommended to do this at a later time, given the desire to
+ avoid potential collisions in legacy user bases.
+
+4. Configuration File Option
+
+4.1. Description
+
+ Once the PXELINUX executable has been entered from the PXE
+ bootloader, it evaluates this option and loads a file of that name
+ via TFTP. The contents of this file serve to configure PXELINUX in
+ its next stage of bootloading (specifying boot image names,
+ locations, boot-time flags, text to present the user in menu
+ selections, etc).
+
+ In the absence of this option, the PXELINUX agent will search the
+ TFTP server (as determined by PXE prior to this stage) for a config
+ file of several default names.
+
+
+
+
+Hankins Informational [Page 5]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+4.2. Packet Format
+
+ The Configuration File Option format is as follows:
+
+ Code Length Config-file...
+ +--------+--------+--------+--------+--------+--------+
+ | 209 | n | c1 | c2 | ... | c(n) |
+ +--------+--------+--------+--------+--------+--------+
+
+ The code for this option is 209. The Config-file (c1..c(n)) is an
+ NVT-ASCII [1] printable string; it is not terminated by a zero or any
+ other value.
+
+4.3. Applicability
+
+ Any bootloader, PXE or otherwise, that makes use of a separate
+ configuration file rather than containing all configurations within
+ DHCP options (which may be impossible due to the limited space
+ available for DHCP options) may conceivably make use of this option.
+
+4.4. Response to RFC 3942
+
+ The code 209 will be adopted for this purpose.
+
+4.5. Client and Server Behaviour
+
+ The Config File Option MUST be supplied by the DHCP server if it
+ appears on the Parameter Request List, but MUST also be supplied if
+ the server administrator believed it would later be useful to the
+ client (such as because the server is configured to offer a second-
+ stage boot image, which they know will make use of it). The option
+ MUST NOT be supplied if no value has been configured for it, or if a
+ value of zero length has been configured.
+
+ The DHCP client MUST only cache this option in a location the second-
+ stage bootloader may access.
+
+ The second-stage bootloader MUST, in concert with other DHCP options
+ and fields, use this option's value as a filename to be loaded via
+ TFTP and read for further second-stage-loader-specific configuration
+ parameters. The format and content of such a file is specific to the
+ second-stage bootloader, and as such, is out of scope of this
+ document.
+
+
+
+
+
+
+
+
+Hankins Informational [Page 6]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+5. Path Prefix Option
+
+5.1. Description
+
+ In PXELINUX' case, it is often the case that several different
+ environments would have the same TFTP path prefix, but would have
+ different filenames (for example: hosts' bootloader images and config
+ files may be kept in a directory structure derived from their Media
+ Access Control (MAC) address). Consequently, it was deemed
+ worthwhile to deliver a TFTP path prefix configuration option, so
+ that these two things could be configured separately in a DHCP Server
+ configuration: the prefix and the possibly host-specific file
+ location.
+
+ The actual filename that PXELINUX requests from its TFTP server is
+ derived by prepending this value to the Config File Option above.
+ Once this config file is loaded and during processing, any TFTP file
+ paths specified within it are similarly processed -- prepending the
+ contents of this option.
+
+5.2. Packet Format
+
+ The Path Prefix Option format is as follows:
+
+ Code Length Path-Prefix...
+ +--------+--------+--------+--------+--------+--------+
+ | 210 | n | p1 | p2 | ... | p(n) |
+ +--------+--------+--------+--------+--------+--------+
+
+ The code for this option is 210. The Path Prefix is an NVT-ASCII
+ printable string; it is not terminated by zero or any other value.
+
+5.3. Applicability
+
+ This option came into existence because server administrators found
+ it useful to configure the prefix and suffix of the config file path
+ separately. A group of different PXE booting clients may use the
+ same path prefix, but different filenames, or vice versa.
+
+ The 'shortcut' this represents is worthwhile, but it is questionable
+ whether that needs to manifest itself on the protocol wire.
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 7]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+ It only becomes interesting from a protocol standpoint if other
+ options are adopted that prefix this value as well -- performing a
+ kind of string compression is highly beneficial to the limited
+ available DHCP option space.
+
+ But it's clearly inapplicable to any current use of, e.g., the
+ FILENAME header contents or the DHCP Boot File Name option (#67).
+ Use of these fields is encoded on firmware of thousands of devices
+ that can't or are not likely to be upgraded. Altering any behaviour
+ here is likely to cause severe compatibility problems.
+
+ Although compression of the TFTP-loaded configuration file contents
+ is not a compelling factor, contrived configurations using these
+ values may also exist: where each of a large variety of different
+ clients load the same configuration file, with the same contents, but
+ due to a differently configured path prefix actually load different
+ images. Whether this sort of use is truly needed remains unproven.
+
+5.4. Response to RFC 3942
+
+ The code 210 will be adopted for this purpose.
+
+5.5. Client and Server Behaviour
+
+ The Path Prefix option MUST be supplied by the DHCP server if it
+ appears on the Parameter Request List, but MUST also be supplied if
+ the server administrator believed it would later be useful to the
+ client (such as because the server is configured to offer a second-
+ stage boot image that they know will make use of it). The option
+ MUST NOT be supplied if no value has been configured for it, or if a
+ value of zero length has been configured.
+
+ The DHCP client MUST only cache this option in a location where the
+ second-stage bootloader may access it.
+
+ The second-stage bootloader MUST prepend this option's value, if any,
+ to the contents of the ConfigFile option prior to obtaining the
+ resulting value via TFTP, or the default 'Config File Search Path',
+ which the second-stage bootloader iterates in the absence of a Config
+ File Option. The client MAY prepend the value to other configuration
+ directives within that file once it has been loaded. The client MUST
+ NOT prepend this option's value to any other DHCP option contents or
+ field, unless explicitly stated in a document describing that option
+ or field.
+
+
+
+
+
+
+
+Hankins Informational [Page 8]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+6. Reboot Time Option
+
+6.1. Description
+
+ Should PXELINUX be executed, and then for some reason, be unable to
+ reach its TFTP server to continue bootstrapping, the client will, by
+ default, reboot itself after 300 seconds have passed. This may be
+ too long, too short, or inappropriate behaviour entirely, depending
+ on the environment.
+
+ By configuring a non-zero value in this option, admins can inform
+ PXELINUX of which specific timeout is desired. The client will
+ reboot itself if it fails to achieve its configured network resources
+ within the specified number of seconds.
+
+ This reboot will run through the system's normal boot-time execution
+ path, most likely leading it back to PXE and therefore PXELINUX. So,
+ in the general case, this is akin to returning the client to the DHCP
+ INIT state.
+
+ By configuring zero, the feature is disabled, and instead the client
+ chooses to remove itself from the network and wait indefinitely for
+ operator intervention.
+
+ It should be stressed that this is in no way related to configuring a
+ lease time. The perceived transition to INIT state is due to client
+ running state -- reinitializing itself -- not due to lease timer
+ activity. That is, it is not safe to assume that a PXELINUX client
+ will abandon its lease when this timer expires.
+
+6.2. Packet Format
+
+ The Reboot Time Option format is as follows:
+
+ Code Length
+ +--------+--------+--------+--------+--------+--------+
+ | 211 | 4 | Reboot Time |
+ +--------+--------+--------+--------+--------+--------+
+
+ The code for this option is 211. The length is always four. The
+ Reboot Time is a 32-bit (4 byte) integer in network byte order.
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 9]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+6.3. Applicability
+
+ Any network bootstrap program in any sufficiently complex networking
+ environment could conceivably enter into such a similar condition,
+ either due to having its IP address stolen out from under it by a
+ rogue client on the network, by being moved between networks where
+ its PXE-derived DHCP lease is no longer valid, or any similar means.
+
+ It seems desirable for any network bootstrap agent to implement an
+ ultimate timeout for it to start over.
+
+ The client may, for example, get different working configuration
+ parameters from a different DHCP server upon restarting.
+
+6.4. Response to RFC 3942
+
+ The code 211 will be adopted for this purpose.
+
+6.5. Client and Server Behaviour
+
+ The Reboot Time Option MUST be supplied by the DHCP server if it
+ appears on the Parameter Request List, but MUST also be supplied if
+ the server administrator believed it would later be useful to the
+ client (such as because the server is configured to offer a second-
+ stage boot image that they know will make use of it). The option
+ MUST NOT be supplied if no value has been configured for it, or if it
+ contains a value of zero length.
+
+ The DHCP client MUST only cache this option in a location the second-
+ stage bootloader may access.
+
+ If the value of this option is nonzero, the second-stage bootloader
+ MUST schedule a timeout: after a number of seconds equal to this
+ option's value have passed, the second-stage bootloader MUST reboot
+ the system, ultimately returning the path of execution back to the
+ first-stage bootloader. It MUST NOT reboot the system once the
+ thread of execution has been passed to the host operating system (at
+ which point, this timeout is effectively obviated).
+
+ If the value of this option is zero, the second-stage bootloader MUST
+ NOT schedule such a timeout at all. Any second-stage bootloader that
+ finds it has encountered excessive timeouts attempting to obtain its
+ host operating system SHOULD disconnect itself from the network to
+ wait for operator intervention, but MAY continue to attempt to
+ acquire the host operating system indefinitely.
+
+
+
+
+
+
+Hankins Informational [Page 10]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+7. Specification Conformance
+
+ To conform to this specification, clients and servers MUST implement
+ the Configuration File, Path Prefix, and Reboot Time options as
+ directed.
+
+ The MAGIC option MAY NOT be implemented, as it has been deprecated.
+
+8. Security Considerations
+
+ PXE and PXELINUX allow any entity acting as a DHCP server to execute
+ arbitrary code upon a system. At present, no PXE implementation is
+ known to implement authentication mechanisms [7] so that PXE clients
+ can be sure they are receiving configuration information from the
+ correct, authoritative DHCP server.
+
+ The use of TFTP by PXE and PXELINUX also lacks any form of
+ cryptographic signature -- so a 'Man in the Middle' attack may lead
+ to an attacker's code being executed on the client system. Since
+ this is not an encrypted channel, any of the TFTP loaded data may
+ also be exposed (such as in loading a "RAMDISK" image, which contains
+ /etc/passwd or similar information).
+
+ The use of the Ethernet MAC Address as the client's unique identity
+ may allow an attacker who takes on that identity to gain
+ inappropriate access to a client system's network resources by being
+ given by the DHCP server whatever 'keys' are required, in fact, to be
+ the target system (to boot up as though it were the target).
+
+ Great care should be taken to secure PXE and PXELINUX installations,
+ such as by using IP firewalls, to reduce or eliminate these concerns.
+
+ A nearby attacker might feed a "Reboot Time" option value of 1 second
+ to a mass of unsuspecting clients, to effect a Denial Of Service
+ (DoS) upon the DHCP server, but then again it may just as easily
+ supply these clients with rogue second-stage bootloaders that simply
+ transmit a flood of packets.
+
+ This document in and by itself provides no security, nor does it
+ impact existing DCHP security as described in RFC 2131 [3].
+
+9. IANA Considerations
+
+ IANA has done the following:
+
+ 1. Moved DHCPv4 Option code 208 from 'Tentatively Assigned' to
+ 'Assigned', referencing this document. IANA has marked this same
+ option code, 208, as Deprecated.
+
+
+
+Hankins Informational [Page 11]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+ 2. Moved DHCPv4 Option code 209 from 'Tentatively Assigned' to
+ 'Assigned', referencing this document.
+
+ 3. Moved DHCPv4 Option code 210 from 'Tentatively Assigned' to
+ 'Assigned', referencing this document.
+
+ 4. Moved DHCPv4 Option code 211 from 'Tentatively Assigned' to
+ 'Assigned', referencing this document.
+
+10. Acknowledgements
+
+ These options were designed and implemented for the PXELINUX project
+ by H. Peter Anvin, and he was instrumental in producing this
+ document. Shane Kerr has also provided feedback that has improved
+ this document.
+
+11. References
+
+11.1. Normative References
+
+ [1] Postel, J. and J. Reynolds, "Telnet Protocol Specification",
+ STD 8, RFC 854, May 1983.
+
+ [2] Bradner, S., "Key words for use in RFCs to Indicate Requirement
+ Levels", BCP 14, RFC 2119, March 1997.
+
+ [3] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
+ March 1997.
+
+ [4] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
+ Extensions", RFC 2132, March 1997.
+
+ [5] Droms, R., "Procedures and IANA Guidelines for Definition of New
+ DHCP Options and Message Types", BCP 43, RFC 2939,
+ September 2000.
+
+11.2. Informative References
+
+ [6] Sollins, K., "The TFTP Protocol (Revision 2)", STD 33, RFC 1350,
+ July 1992.
+
+ [7] Droms, R. and W. Arbaugh, "Authentication for DHCP Messages",
+ RFC 3118, June 2001.
+
+ [8] Volz, B., "Reclassifying Dynamic Host Configuration Protocol
+ version 4 (DHCPv4) Options", RFC 3942, November 2004.
+
+
+
+
+
+Hankins Informational [Page 12]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+Author's Address
+
+ David W. Hankins
+ Internet Systems Consortium, Inc.
+ 950 Charter Street
+ Redwood City, CA 94063
+ US
+
+ Phone: +1 650 423 1307
+ EMail: David_Hankins@isc.org
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 13]
+
+RFC 5071 PXELINUX Options December 2007
+
+
+Full Copyright Statement
+
+ Copyright (C) The IETF Trust (2007).
+
+ This document is subject to the rights, licenses and restrictions
+ contained in BCP 78, and except as set forth therein, the authors
+ retain all their rights.
+
+ This document and the information contained herein are provided on an
+ "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
+ OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
+ THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
+ OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
+ THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
+ WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
+
+Intellectual Property
+
+ The IETF takes no position regarding the validity or scope of any
+ Intellectual Property Rights or other rights that might be claimed to
+ pertain to the implementation or use of the technology described in
+ this document or the extent to which any license under such rights
+ might or might not be available; nor does it represent that it has
+ made any independent effort to identify any such rights. Information
+ on the procedures with respect to rights in RFC documents can be
+ found in BCP 78 and BCP 79.
+
+ Copies of IPR disclosures made to the IETF Secretariat and any
+ assurances of licenses to be made available, or the result of an
+ attempt made to obtain a general license or permission for the use of
+ such proprietary rights by implementers or users of this
+ specification can be obtained from the IETF on-line IPR repository at
+ http://www.ietf.org/ipr.
+
+ The IETF invites any interested party to bring to its attention any
+ copyrights, patents or patent applications, or other proprietary
+ rights that may cover technology that may be required to implement
+ this standard. Please address the information to the IETF at
+ ietf-ipr@ietf.org.
+
+
+
+
+
+
+
+
+
+
+
+
+Hankins Informational [Page 14]
+