wdiff draft-ietf-netconf-tls-06.txt draft-ietf-netconf-tls-07.txt

NETCONF Working Group Mohamad M. Badra
Internet Draft LIMOS
Internet-Draft CNRS/LIMOS Laboratory
Intended status: Standards Track October 22, 2008 February 24, 2009
Expires: April August 28, 2009

NETCONF over Over Transport Layer Security (TLS)
draft-ietf-netconf-tls-06.txt
draft-ietf-netconf-tls-07.txt

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Abstract

The Network Configuration Protocol (NETCONF) provides mechanisms to
install, manipulate, and delete the configuration of network devices.
This document describes how to use the Transport Layer Security (TLS)
protocol to secure NETCONF exchanges.

Table of Contents

1. Introduction...................................................3 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Conventions used Used in this document.........................3 Document . . . . . . . . . . . . . 3
2. NETCONF over TLS...............................................3 TLS . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Connection Initiation.....................................3 Initiation . . . . . . . . . . . . . . . . . . . 3
2.2. Connection Closure........................................4 Closure . . . . . . . . . . . . . . . . . . . . 4
3. Endpoint Authentication and Identification.....................5 Identification . . . . . . . . . . 5
3.1. Server Identity...........................................5 Identity . . . . . . . . . . . . . . . . . . . . . . 5
3.2. Client Identity...........................................6 Identity . . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations........................................6 Considerations . . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations............................................6 Considerations . . . . . . . . . . . . . . . . . . . . . . 7
6. Acknowledgments................................................7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
7. References.....................................................7
7.1. Contributor's Address . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References......................................7 References . . . . . . . . . . . . . . . . . . . . . 7
Appendix A. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . . 8
A.1. 06-07 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
A.2. 05-06 . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
A.3. 04-05 . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Author's Addresses................................................8
Intellectual Property and Copyright Statement.....................8 Address . . . . . . . . . . . . . . . . . . . . . . . . . 9

1. Introduction

The NETCONF protocol [RFC4741] defines a mechanism through which a
network device can be managed. NETCONF is connection-oriented,
requiring a persistent connection between peers. This connection
must provide reliable, sequenced data delivery, integrity and
confidentiality and peers authentication.

This document defines "NETCONF over TLS", which includes support for
certificate-based mutual authentication and key derivation, utilizing
the protected ciphersuite negotiation, mutual authentication and key
management capabilities of the TLS (Transport Layer Security)
protocol, described in [RFC5246].

Throughout this document, the terms "client" and "server" are used to
refer to the two ends of the TLS connection. The client actively
opens the TLS connection, and the server passively listens for the
incoming TLS connection. The terms "manager" and "agent" are used to
refer to the two ends of the NETCONF protocol session. The manager
issues NETCONF remote procedure call (RPC) commands, and the agent
replies to those commands. When NETCONF is run over TLS using the
mapping defined in this document, the client is always the manager,
and the server is always the agent.

1.1. Conventions used Used in this document Document

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC-2119 [RFC2119].

2. NETCONF over TLS

Since TLS is application protocol-independent, NETCONF can operate on
top of the TLS protocol transparently. This document defines how
NETCONF can be used within a TLS session.

2.1. Connection Initiation

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
incoming TLS connection on the TCP port <IANA-to-be-assigned>. (Note
to RFC Editor: please replace <IANA-to-be-assigned> with the IANA-
assigned value, and remove this note). It MUST therefore send the
TLS ClientHello message to begin the TLS handshake. Once the TLS
handshake has finished, the client and the server MAY begin to
exchange NETCONF data. In particular, the client will send complete
XML documents to the server containing <rpc> elements, and the server
will respond with complete XML documents containing <rpc-reply>
elements. The client MAY indicate interest in receiving event
notifications from a server by creating a subscription to receive
event notifications [RFC5277], in which case the server replies to
indicate whether the subscription request was successful and, if it
was successful, begins sending the event notifications to the client
as the events occur within the system.

All NETCONF messages MUST be sent as TLS "application data". It is
possible that multiple NETCONF messages be contained in one TLS
record, or that a NETCONF message be transferred in multiple TLS
records.

Current NETCONF messages don't include a message's length.

This document uses consequently the same delimiter sequence ("]]>]]>") defined in
[RFC4742]
[RFC4742], which MUST be sent by both the client and therefore the special server after
each XML document in the NETCONF exchange. Since this character sequence, ]]>]]>, to
delimit
sequence can legally appear in plain XML documents. in attribute values,
comments, and processing instructions, implementations of this
document MUST ensure that this character sequence is never part of a
NETCONF message.

Implementation of the protocol specified in this document MAY
implement any TLS cipher suite that provides certificate-based mutual
authentication [RFC5246].

Implementations MUST support TLS 1.2 [RFC5246] and are REQUIRED to
support the mandatory to implement cipher suite, which is
TLS_RSA_WITH_AES_128_CBC_SHA. This document is assumed to apply to
future versions of TLS, in which case the mandatory to implement
cipher suite for the implemented version MUST be supported.

2.2. Connection Closure

A TLS client (NETCONF manager) MUST close the associated TLS
connection if the connection is not expected to issues issue any NETCONF RPC
commands later. It MUST send a TLS close_notify alert before closing
the connection. The TLS client MAY choose to not wait for the TLS
server (NETCONF agent) close_notify alert and simply close the
connection, thus generating an incomplete close on the TLS server
side. Once the TLS server gets a close_notify from the TLS client,
it MUST reply with a close_notify unless it becomes aware that the
connection has already been closed by the TLS client (e.g., the
closure was indicated by TCP).

When no data is received from a connection for a long time (where the
application decides what "long" means), a NETCONF peer MAY close the
connection. The NETCONF peer MUST attempt to initiate an exchange of
close_notify alerts with the other NETCONF peer before closing the
connection. The close_notify's sender that is unprepared to receive
any more data MAY close the connection after sending the close_notify
alert, thus generating an incomplete close on the close_notify's
receiver side.

3. Endpoint Authentication and Identification

3.1. Server Identity

During the TLS negotiation, the client MUST carefully examine the
certificate presented by the server to determine if it meets their
expectations. Particularly, the client MUST check its understanding
of the server hostname against the server's identity as presented in
the server Certificate message, in order to prevent man-in-the-middle
attacks.

Matching is performed according to the rules below (following the
example of [RFC4642]):

o The client MUST use the server hostname it used to open the
connection (or the hostname specified in TLS "server_name"
extension [RFC4366]) [RFC5246]) as the value to compare against the server
name as expressed in the server certificate. The client MUST NOT
use any form of the server hostname derived from an insecure
remote source (e.g., insecure DNS lookup). CNAME canonicalization
is not done.

o If a subjectAltName extension of type dNSName is present in the
certificate, it MUST be used as the source of the server's
identity.

o Matching is case-insensitive.

o A "*" wildcard character MAY be used as the leftmost name
component in the certificate. For example, *.example.com would
match a.example.com, foo.example.com, etc., but would not match
example.com.

o If the certificate contains multiple names (e.g., more than one
dNSName field), then a match with any one of the fields is
considered acceptable.

If the match fails, the client MUST either ask for explicit user
confirmation or terminate the connection and indicate the server's
identity is suspect.

Additionally, clients MUST verify the binding between the identity of
the servers to which they connect and the public keys presented by
those servers. Clients SHOULD implement the algorithm in Section 6
of [RFC5280] for general certificate validation, but MAY supplement
that algorithm with other validation methods that achieve equivalent
levels of verification (such as comparing the server certificate
against a local store of already-verified certificates and identity
bindings).

If the client has external information as to the expected identity of
the server, the hostname check MAY be omitted.

3.2. Client Identity

Typically, the

The server has may have no external knowledge of what the on client's identity ought to be and so
identity checks (other than that might not be possible (unless the client has a
certificate chain rooted in an appropriate CA) are not possible. CA). If a server has such
knowledge on client's identity (typically from some source external
to NETCONF or TLS) it MUST check the identity as described above.

4. Security Considerations

The security considerations described throughout [RFC5246] and
[RFC4741] apply here as well.

This document in its current version doesn't does not support third party
authentication due to the fact that TLS doesn't does not specify this way of
authentication and that NETCONF depends on the transport protocol for
the authentication service. If third party authentication is needed,
BEEP or SSH transport can be used.

An attacker might be able to inject arbitrary NETCONF messages via
some application that does not carefully check exchanged messages or
deliberately insert the delimiter sequence in a NETCONF message to
create a DoS attack. Hence, applications and NETCONF APIs MUST
ensure that the delimiter sequence defined in Section 2.1 never
appears in NETCONF messages; otherwise, those messages can be
dropped, garbled or mis-interpreted. If the delimiter sequence is
found in a NETCONF message by the sender side, a robust
implementation of this document should warn the user that illegal
characters have been discovered. If the delimiter sequence is found
in a NETCONF message by the receiver side (including any XML
attribute values, XML comments or processing instructions) a robust
implementation of this document must silently discard the message
without further processing and then stop the NETCONF session.

Finally, this document does not introduce any new security
considerations compared to [RFC4742].

5. IANA Considerations

IANA is requested to assign a TCP port number in the "Registered Port
Numbers" range with the name "netconf-tls". This port will be the
default port for NETCONF over TLS, as defined in this document.

Registration Contact: Mohamad Badra, badra@isima.fr.
Transport Protocol: TCP.
Port Number: TBA-by-IANA (if possible, please assign 6513).
Broadcast, Multicast or Anycast: No.
Port Name: netconf-tls.
Service Name: netconf.
Reference: draft-ietf-netconf-tls-05. draft-ietf-netconf-tls-07.

6. Acknowledgments Acknowledgements

A significant amount of the text in Section 3 was lifted from
[RFC4642].

The author would like to acknowledge David Harrington, Miao Fuyou,
Eric Rescorla, Juergen Schoenwaelder, Simon Josefsson, Olivier
Coupelon, Alfred Hoenes and the NETCONF mailing list members for
their comments on the document. The author appreciates also Bert
Wijnen, Mehmet Ersue and Dan Romascanu for their efforts on issues
resolving discussion, and Charlie Kaufman, Pasi Eronen and Tim Polk
for the thorough review of this document.

7. References

7.1. Contributor's Address

Ibrahim Hajjeh
Ineovation
France

E-mail: ibrahim.hajjeh@ineovation.fr

8. Normative References

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.

[RFC4366] Blake-Wilson, S., Nystrom, M., Hopwood, D., Mikkelsen, J.,
and T. Wright, "Transport Layer Security (TLS) Extensions",
RFC 4366, April 2006.

[RFC4642] Murchison, K., Vinocur, J., and C. Newman, C., "Using
Transport Layer Security (TLS) with Network News Transfer
Protocol (NNTP)", RFC 4642, October 2006 2006.

[RFC4741] Enns, R., "NETCONF Configuration Protocol", RFC 4741,
December 2006.

[RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF
Configuration Protocol over Secure Shell SHell (SSH)", RFC 4742,
December 2006.

[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC5246, RFC 5246, August 2008.

[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
LIMOS Laboratory - UMR6158, CNRS
France

Email: badra@isima.fr

Contributors

Ibrahim Hajjeh
INEOVATION
France

Email: Ibrahim.hajjeh@ineovation.com

Full Copyright Statement

This document is subject

Appendix A. Change Log (to be removed by RFC Editor before publication)

A.1. 06-07

New trust boilerplate introduced.

Section 2.1: reworded the text related to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.

This document delimiter sequence 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

The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights
highlighted 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 implementations MUST ensure that it has
made delimiter sequence
is never part of a NETCONF message.

Section 2.2: Obselete RFC4366 is replaced with RFC5246.

Section 2.2: s/to issues any independent effort to identify NETCONF commands/to issue any such rights. Information
on NETCONF
commands/

Section 3.2: "Typically, the procedures server has no external knowledge" is
replaced with respect "The server may have no external knowledge"

Section 4 : text added to rights in RFC documents can be
found in BCP 78 the Security Considerations section to
describe security threads and BCP 79.

Copies of IPR disclosures made to give recommendations on the IETF Secretariat sender
and any
assurances of licenses to be made available, or receiver behaviour in case they detect the result of an
attempt made to obtain delimiter sequence in
between 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 NETCONF message.

A.2. 05-06

Section 5 (IANA Considerations Section): "Anycast" is replaced with
"No".

A.3. 04-05

Removed any interested party text related to bring PSK based authentication.

Revised to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required TLS with certificate-based mutual authentication.

Removed Cipher Suite Requirements section which was redundant with
TLS.

Added small clarifications to implement
this standard. Please address the information "Introduction" and "Endpoint
Authentication and Identification" sections.

Section 2.1: Included mandatory to implement cipher suites that
track future versions of the IETF at
ietf-ipr@ietf.org.

Acknowledgment

Funding for TLS.

Section 2.2: Revised the RFC Editor function is provided by connection closure session with regards to
TLS 1.2.

Section 5: Revised to help IANA with the IETF
Administrative Support Activity (IASA). port assignment.

Section 8: Removed RFC4086 and RFC4279 from the reference section

Author's Address

Mohamad Badra
CNRS/LIMOS Laboratory
Campus de cezeaux, Bat. ISIMA
Aubiere, 63170
Fance

Email: badra@isima.fr