draft-ietf-netconf-tls-03.txt   draft-ietf-netconf-tls-04.txt 
NETCONF Working Group Mohamad Badra NETCONF Working Group Mohamad Badra
Internet Draft LIMOS Laboratory Internet Draft LIMOS Laboratory
Intended status: Standards Track June 5, 2008 Intended status: Standards Track September 2, 2008
Expires: December 2008
NETCONF over Transport Layer Security (TLS) NETCONF over Transport Layer Security (TLS)
draft-ietf-netconf-tls-03.txt draft-ietf-netconf-tls-04.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on December 5, 2008. This Internet-Draft will expire on March 2, 2009.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
Abstract Abstract
The Network Configuration Protocol (NETCONF) provides mechanisms to The Network Configuration Protocol (NETCONF) provides mechanisms to
install, manipulate, and delete the configuration of network devices. install, manipulate, and delete the configuration of network devices.
This document describes how to use the Transport Layer Protocol (TLS) This document describes how to use the Transport Layer Protocol (TLS)
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Table of Contents Table of Contents
1. Introduction...................................................3 1. Introduction...................................................3
1.1. Conventions used in this document.........................3 1.1. Conventions used in this document.........................3
2. NETCONF over TLS...............................................3 2. NETCONF over TLS...............................................3
2.1. Connection Initiation.....................................3 2.1. Connection Initiation.....................................3
2.2. Connection Closure........................................4 2.2. Connection Closure........................................4
3. Endpoint Authentication and Identification.....................4 3. Endpoint Authentication and Identification.....................4
3.1. Server Identity...........................................5 3.1. Server Identity...........................................5
3.2. Client Identity...........................................6 3.2. Client Identity...........................................6
3.3. Password-Based Authentication.............................6 3.3. Pre-shared key Authentication.............................6
4. Cipher Suite Requirements......................................7 4. Cipher Suite Requirements......................................7
5. Security Considerations........................................7 5. Security Considerations........................................7
6. IANA Considerations............................................8 6. IANA Considerations............................................7
7. Acknowledgments................................................8 7. Acknowledgments................................................7
A. Appendix - Test Vectors for the PSK Derivation Function........9 8. References.....................................................8
Normative References..............................................9 8.1. Normative References......................................8
Authors' Addresses...............................................10
Intellectual Property Statement..................................10
Disclaimer of Validity...........................................11
1. Introduction 1. Introduction
The NETCONF protocol [RFC4741] defines a simple mechanism through The NETCONF protocol [RFC4741] defines a simple mechanism through
which a network device can be managed. NETCONF is connection- which a network device can be managed. NETCONF is connection-
oriented, requiring a persistent connection between peers. This oriented, requiring a persistent connection between peers. This
connection must provide reliable, sequenced data delivery, integrity connection must provide reliable, sequenced data delivery, integrity
and confidentiality and peers authentication. This document and confidentiality and peers authentication. This document
describes how to use TLS [RFC4346] to secure NETCONF connections. describes how to use TLS [RFC5246] to secure NETCONF connections.
Throughout this document, the terms "client" and "server" are used to Throughout this document, the terms "client" and "server" are used to
refer to the two ends of the TLS connection. The client actively refer to the two ends of the TLS connection. The client actively
opens the TLS connection, and the server passively listens for the opens the TLS connection, and the server passively listens for the
incoming TLS connection. The terms "manager" and "agent" are used to incoming TLS connection. The terms "manager" and "agent" are used to
refer to the two ends of the NETCONF protocol session. The manager refer to the two ends of the NETCONF protocol session. The manager
issues NETCONF remote procedure call (RPC) commands, and the agent issues NETCONF remote procedure call (RPC) commands, and the agent
replies to those commands. When NETCONF is run over TLS using the replies to those commands. When NETCONF is run over TLS using the
mapping defined in this document, the client is always the manager, mapping defined in this document, the client is always the manager,
and the server is always the agent. and the server is always the agent.
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The peer acting as the NETCONF manager MUST also act as the TLS The peer acting as the NETCONF manager MUST also act as the TLS
client. It MUST connect to the server that passively listens for the client. It MUST connect to the server that passively listens for the
incoming TLS connection on the IANA-to-be-assigned TCP port <TBA>. incoming TLS connection on the IANA-to-be-assigned TCP port <TBA>.
It MUST therefore send the TLS ClientHello to begin the TLS It MUST therefore send the TLS ClientHello to begin the TLS
handshake. Once the TLS handshake has been finished, the client and handshake. Once the TLS handshake has been finished, the client and
the server MAY then send their NETCONF exchanges. In particular, the the server MAY then send their NETCONF exchanges. In particular, the
client will send complete XML documents to the server containing client will send complete XML documents to the server containing
<rpc> elements, and the server will respond with complete XML <rpc> elements, and the server will respond with complete XML
documents containing <rpc-reply> elements. The client MAY indicate documents containing <rpc-reply> elements. The client MAY indicate
interest in receiving event notifications from a NETCONF server by interest in receiving event notifications from a NETCONF server by
creating a subscription to receive event notifications [I-D.ietf- creating a subscription to receive event notifications [RFC5277], in
netconf-notification], in which the NETCONF server replies to which the NETCONF server replies to indicate whether the subscription
indicate whether the subscription request was successful and, if it request was successful and, if it was successful, begins sending the
was successful, begins sending the event notifications to the NETCONF event notifications to the NETCONF client as the events occur within
client as the events occur within the system. All these elements are the system. All these elements are encapsulated into TLS records of
encapsulated into TLS records of type "application data". These type "application data". These records are protected using the TLS
records are protected using the TLS material keys. material keys.
Current NETCONF messages don't include a message's length. This Current NETCONF messages don't include a message's length. This
document uses consequently the same delimiter sequence defined in document uses consequently the same delimiter sequence defined in
[RFC4742] and therefore the special character sequence, ]]>]]>, to [RFC4742] and therefore the special character sequence, ]]>]]>, to
delimit XML documents. delimit XML documents.
2.2. Connection Closure 2.2. Connection Closure
Either NETCONF peer MAY stop the NETCONF connection at any time and Either NETCONF peer MAY stop the NETCONF connection at any time and
therefore notify the other NETCONF peer that no more data on this therefore notify the other NETCONF peer that no more data on this
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from a connection for a long time, where the application decides what from a connection for a long time, where the application decides what
"long" means. "long" means.
TLS has the ability for secure connection closure using the Alert TLS has the ability for secure connection closure using the Alert
protocol. When the NETCONF peer closes the NETCONF connection, it protocol. When the NETCONF peer closes the NETCONF connection, it
MUST send a TLS close_notify alert before closing the TCP connection. MUST send a TLS close_notify alert before closing the TCP connection.
Any data received after a closure alert is ignored. Any data received after a closure alert is ignored.
Unless a fatal error has occurred, each party is required to send a Unless a fatal error has occurred, each party is required to send a
close_notify alert before closing the write side of the connection close_notify alert before closing the write side of the connection
[RFC4346]. The other party MUST respond with a close_notify alert of [RFC5246]. The other party MUST respond with a close_notify alert of
its own and close down the connection immediately, discarding any its own and close down the connection immediately, discarding any
pending writes. It is not required for the initiator of the close to pending writes. It is not required for the initiator of the close to
wait for the responding close_notify alert before closing the read wait for the responding close_notify alert before closing the read
side of the connection. side of the connection.
3. Endpoint Authentication and Identification 3. Endpoint Authentication and Identification
NETCONF requires that its transport provide mutual authentication of NETCONF requires that its transport provide mutual authentication of
client and server, so cipher suites that are anonymous or which only client and server, so cipher suites that are anonymous or which only
authenticate the server to the client MUST NOT be used with NETCONF. authenticate the server to the client MUST NOT be used with NETCONF.
This document specifies how to use TLS with endpoint authentication, This document specifies how to use TLS with endpoint authentication,
which can be based on either preshared keys [RFC4279] or public key which can be based on either preshared keys [RFC4279] or public key
certificates [RFC4346]. Some cipher suites (e.g. certificates [RFC5246]. Some cipher suites (e.g.
TLS_RSA_PSK_WITH_AES_128_CBC_SHA) use both. Section 3.1 describes TLS_RSA_PSK_WITH_AES_128_CBC_SHA) use both. Section 3.1 describes
how the client authenticates the server if public key certificates how the client authenticates the server if public key certificates
are provided by the server, section 3.2 describes how the server are provided by the server, section 3.2 describes how the server
authenticates the client if public key certificates are provided by authenticates the client if public key certificates are provided by
the client, and section 3.3 describes how the client and server the client, and section 3.3 describes how the client and server
mutually authenticate one another using a password. mutually authenticate one another using a pre-shared key (PSK).
3.1. Server Identity 3.1. Server Identity
During the TLS negotiation, the client MUST carefully examine the During the TLS negotiation, the client MUST carefully examine the
certificate presented by the server to determine if it meets their certificate presented by the server to determine if it meets their
expectations. Particularly, the client MUST check its understanding expectations. Particularly, the client MUST check its understanding
of the server hostname against the server's identity as presented in of the server hostname against the server's identity as presented in
the server Certificate message, in order to prevent man-in-the-middle the server Certificate message, in order to prevent man-in-the-middle
attacks. attacks.
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the server, the hostname check MAY be omitted. the server, the hostname check MAY be omitted.
3.2. Client Identity 3.2. Client Identity
Typically, the server has no external knowledge of what the client's Typically, the server has no external knowledge of what the client's
identity ought to be and so checks (other than that the client has a identity ought to be and so checks (other than that the client has a
certificate chain rooted in an appropriate CA) are not possible. If certificate chain rooted in an appropriate CA) are not possible. If
a server has such knowledge (typically from some source external to a server has such knowledge (typically from some source external to
NETCONF or TLS) it MUST check the identity as described above. NETCONF or TLS) it MUST check the identity as described above.
3.3. Password-Based Authentication 3.3. Pre-shared key Authentication
[RFC4279] supports authentication based on pre-shared keys (PSKs). [RFC4279] supports authentication based on pre-shared keys (PSKs).
These pre-shared keys are symmetric keys, shared in advance among the These pre-shared keys are symmetric keys, shared in advance among the
communicating parties. communicating parties.
The PSK can be generated in many ways and its length is variable. The PSK can be generated in many ways and its length is variable. It
Implementation of this document MAY rely on [RFC4279] to enable is RECOMMENDED that implementations that allow the administrator to
password based user authentication. In this case, the password is manually configure the PSK also provide functionality for generating
used to generate the PSK. It is RECOMMENDED that implementations a new random PSK, taking [RFC4086] into account.
that allow the administrator to manually configure the password also
provide functionality for generating a new random password, taking
[RFC4086] into account.
This document generates the PSK from the password as follow:
PSK = SHA-1(SHA-1(psk_identity + "Key Pad for Netconf" + password) +
psk_identity_hint)
Where + means concatenation.
The label "Key Pad for Netconf" is an ASCII string.
The psk_identity_hint is initially defined in section 5.1 of If both the client and the server agree on using the pre-shared key
[RFC4279]. The psk_identity_hint can do double duty and also provide authentication, the server can provide a "PSK identity hint" in the
a form of server authentication in the case where the user has the ServerKeyExchange message. If a hint is provided, the
same password on a number of NETCONF servers. If a hint is provided, psk_identity_hint is encoded in the same way as in [RFC4279] and
the psk_identity_hint is encoded in the same way as in [RFC4279] and
should be a string representation of the name of the server should be a string representation of the name of the server
recognizable to the administrator or his software. In the case where recognizable to the administrator or his software. In the case where
the user types a server name to connect to, it should be that string. the user types a server name to connect to, it should be that string.
If the string the user enters differs from the one returned as If the string the user enters differs from the one returned as
psk_identity_hint, the software could display the server's name and psk_identity_hint, the software could display the server's name and
ask the user to confirm. For automated scripts, the names could be ask the user to confirm. For automated scripts, the names could be
expected to match. It is highly recommended that implementations set expected to match. It is highly recommended that implementations set
the psk_identity_hint to the DNS name of the NETCONF server (i.e., the psk_identity_hint to the DNS name of the NETCONF server (i.e.,
the TLS server). the TLS server).
It is RECOMMENDED that users choose different passwords for the It is RECOMMENDED that users choose different PSKs for the different
different servers they manage. servers they manage.
Note 1: The NETCONF over TLS implementation need not store the
password in clear text, but rather can store the value of the
inner SHA-1, (SHA-1(psk_identity + "Key Pad for Netconf" +
password)), which could not be used as a password equivalent for
applications other than NETCONF. Deriving the PSK from a password
is not secure. This construction is used because it is
anticipated that people will do it anyway.
Note 2: [RFC4279] defines some conformance requirements for the [RFC4279] defines some conformance requirements for the PSK, for the
PSK, for the PSK identity encoding and for the identity hint. The PSK identity encoding and for the identity hint. Moreover, it
same requirements apply here as well; in particular on the describes the management interface requirements for entering the PSK
password. Moreover, the management interface by which the and/or PSK identity (See Section 5 of [RFC4279] for a more detailed
password is provided MUST accept ASCII strings of at least 64 description of these requirements). Those same requirements apply
octets and MUST NOT add a null terminator before using them as here as well.
shared secrets. It MUST also accept a HEX encoding of the
password. The management interface MAY accept other encodings if
the algorithm for translating the encoding to a binary string is
specified.
4. Cipher Suite Requirements 4. Cipher Suite Requirements
A compliant implementation of the protocol specified in this document A compliant implementation of the protocol specified in this document
MUST implement the cipher suite TLS_DHE_PSK_WITH_AES_128_CBC_SHA and MUST implement the cipher suite TLS_DHE_PSK_WITH_AES_128_CBC_SHA and
MAY implement any TLS cipher suite that provides mutual MAY implement any TLS cipher suite that provides mutual
authentication. authentication.
5. Security Considerations 5. Security Considerations
The security considerations described throughout [RFC4346] and The security considerations described throughout [RFC5246] and
[RFC4279] apply here as well. [RFC4279] apply here as well.
This document in its current version doesn't support third party This document in its current version doesn't support third party
authentication due to the fact that TLS doesn't specify this way of authentication due to the fact that TLS doesn't specify this way of
authentication and that NETCONF depends on the transport protocol for authentication and that NETCONF depends on the transport protocol for
the authentication service. If third party authentication is needed, the authentication service. If third party authentication is needed,
BEEP or SSH transport can be used. BEEP or SSH transport can be used.
As with all schemes involving shared keys and passwords, special care As with all schemes involving shared keys, special care should be
should be taken to protect the shared values and passwords as well as taken to protect the shared secret as well as to limit its exposure
to limit their exposure over time. Alternatively, using certificates over time. Alternatively, using certificates would provide better
would provide better protection. protection.
6. IANA Considerations 6. IANA Considerations
IANA is requested to assign a TCP port number that will be the IANA is requested to assign a TCP port number that will be the
default port for NETCONF over TLS sessions as defined in this default port for NETCONF over TLS sessions as defined in this
document. document.
IANA has assigned port <TBA> for this purpose. IANA has assigned port <TBA> for this purpose.
7. Acknowledgments 7. Acknowledgments
A significant amount of the text in Section 3.1 was lifted from A significant amount of the text in Section 3.1 was lifted from
[RFC4642]. [RFC4642].
The author would like to acknowledge David Harrington, Miao Fuyou, The author would like to acknowledge David Harrington, Miao Fuyou,
Eric Rescorla, Juergen Schoenwaelder, Simon Josefsson, Olivier Eric Rescorla, Juergen Schoenwaelder, Simon Josefsson, Olivier
Coupelon and the NETCONF mailing list members for their comments on Coupelon and the NETCONF mailing list members for their comments on
the document. The author appreciates also Bert Wijnen, Mehmet Ersue the document. The author appreciates also Bert Wijnen, Mehmet Ersue
and Dan Romascanu for their efforts on issues resolving discussion, and Dan Romascanu for their efforts on issues resolving discussion,
and Charlie Kaufman for the thorough review of this document and for and Charlie Kaufman, Pasi Eronen and Tim Polk for the thorough review
the helpful comments on the password-based authentication. of this document.
A. Appendix - Test Vectors for the PSK Derivation Function
The test vectors for the PSK derivation function in this document
have been cross-verified by two independent implementations. An
implementation that concurs with the results provided in this
document should be interoperable with other similar implementations.
password = password
psk_identity = psk_identity
psk_identity_hint = psk_identity_hint
The inner SHA-1 value (in hex):
inner := SHA-1(psk_identity + "Key Pad for Netconf" + password)
== SHA-1("psk_identityKey Pad for Netconfpassword")
=> 6d6eeb6a b8d0466b 45245d07 47d86726 b41b868c
The outer SHA-1 value (in hex):
outer := SHA-1(inner + psk_identity_hint) 8. References
=> 88f3824b 3e5659f5 2d00e959 bacab954 b6540344
Normative References 8.1. Normative References
[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.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
[RFC4086] Eastlake, D., 3rd, Schiller, J., and S. Crocker, [RFC4086] Eastlake, D., 3rd, Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086, "Randomness Requirements for Security", BCP 106, RFC 4086,
June 2005. June 2005.
[RFC4279] Eronen, P. and H. Tschofenig., "Pre-Shared Key Ciphersuites [RFC4279] Eronen, P. and H. Tschofenig., "Pre-Shared Key Ciphersuites
for Transport Layer Security (TLS)", RFC 4279, December for Transport Layer Security (TLS)", RFC 4279, December
2005. 2005.
[RFC4346] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol 1.1", RFC 4346, April 2006.
[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J., [RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
and T. Wright, "Transport Layer Security (TLS) Extensions", and T. Wright, "Transport Layer Security (TLS) Extensions",
RFC 4366, April 2006. RFC 4366, April 2006.
[RFC4642] Murchison, K., Vinocur, J., Newman, C., "Using Transport [RFC4642] Murchison, K., Vinocur, J., Newman, C., "Using Transport
Layer Security (TLS) with Network News Transfer Protocol Layer Security (TLS) with Network News Transfer Protocol
(NNTP)", RFC 4642, October 2006 (NNTP)", RFC 4642, October 2006
[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741, [RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006. December 2006.
[RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF [RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF
Configuration Protocol over Secure Shell (SSH)", RFC 4742, Configuration Protocol over Secure Shell (SSH)", RFC 4742,
December 2006. December 2006.
[I-D.ietf-netconf-notification] [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
Chisholm, S. and H. Trevino, "NETCONF Event Notifications", (TLS) Protocol 1.2", RFC5246, August 2008.
draft-ietf-netconf-notification-13.txt, (work in progress),
May 2008.
Authors' Addresses [RFC5277] Chisholm, S. and H. Trevino, "NETCONF Event Notifications",
RFC 5277, July 2008.
[RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S.,
Housley, R., and W. Polk, "Internet X.509 Public Key
Infrastructure Certificate and Certificate Revocation List
(CRL) Profile", RFC 5280, May 2008.
Author's Addresses
Mohamad Badra Mohamad Badra
LIMOS Laboratory - UMR6158, CNRS LIMOS Laboratory - UMR6158, CNRS
France France
Email: badra@isima.fr Email: badra@isima.fr
Contributors Contributors
Ibrahim Hajjeh Ibrahim Hajjeh
INEOVATION INEOVATION
France France
Email: hajjeh@ineovation.com Email: hajjeh@ineovation.com
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
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 Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights 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 might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 11, line 12 skipping to change at line 387
attempt made to obtain a general license or permission for the use of attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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rights that may cover technology that may be required to implement rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at this standard. Please address the information to the IETF at
ietf-ipr@ietf.org. ietf-ipr@ietf.org.
Disclaimer of Validity
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.
Copyright Statement
Copyright (C) The IETF Trust (2008).
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.
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
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