draft-ietf-netconf-tls-04.txt   draft-ietf-netconf-tls-05.txt 
NETCONF Working Group Mohamad Badra NETCONF Working Group Mohamad Badra
Internet Draft LIMOS Laboratory Internet Draft LIMOS Laboratory
Intended status: Standards Track September 2, 2008 Intended status: Standards Track October 17, 2008
NETCONF over Transport Layer Security (TLS) NETCONF over Transport Layer Security (TLS)
draft-ietf-netconf-tls-04.txt draft-ietf-netconf-tls-05.txt
Status of this Memo Status of this Memo
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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 Security (TLS)
to secure NETCONF exchanges. protocol to secure NETCONF exchanges.
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.....................5
3.1. Server Identity...........................................5 3.1. Server Identity...........................................5
3.2. Client Identity...........................................6 3.2. Client Identity...........................................6
3.3. Pre-shared key Authentication.............................6 4. Security Considerations........................................6
4. Cipher Suite Requirements......................................7 5. IANA Considerations............................................6
5. Security Considerations........................................7 6. Acknowledgments................................................7
6. IANA Considerations............................................7 7. References.....................................................7
7. Acknowledgments................................................7 7.1. Normative References......................................7
8. References.....................................................8 Author's Addresses................................................8
8.1. Normative References......................................8 Intellectual Property and Copyright Statement.....................8
1. Introduction 1. Introduction
The NETCONF protocol [RFC4741] defines a simple mechanism through The NETCONF protocol [RFC4741] defines a mechanism through which a
which a network device can be managed. NETCONF is connection- network device can be managed. NETCONF is connection-oriented,
oriented, requiring a persistent connection between peers. This requiring a persistent connection between peers. This connection
connection must provide reliable, sequenced data delivery, integrity must provide reliable, sequenced data delivery, integrity and
and confidentiality and peers authentication. This document confidentiality and peers authentication.
describes how to use TLS [RFC5246] to secure NETCONF connections.
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 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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1.1. Conventions used in this document 1.1. Conventions used in this document
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].
2. NETCONF over TLS 2. NETCONF over TLS
Since TLS is application protocol-independent, NETCONF can operate on Since TLS is application protocol-independent, NETCONF can operate on
top of the TLS protocol transparently. This document defines how top of the TLS protocol transparently. This document defines how
NETCONF can be used within a Transport Layer Security (TLS) session. NETCONF can be used within a TLS session.
2.1. Connection Initiation 2.1. Connection Initiation
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 TCP port <IANA-to-be-assigned>. (Note
It MUST therefore send the TLS ClientHello to begin the TLS to RFC Editor: please replace <IANA-to-be-assigned> with the IANA-
handshake. Once the TLS handshake has been finished, the client and assigned value, and remove this note). It MUST therefore send the
the server MAY then send their NETCONF exchanges. In particular, the TLS ClientHello to begin the TLS handshake. Once the TLS handshake
client will send complete XML documents to the server containing has finished, the client and the server MAY begin to exchange NETCONF
<rpc> elements, and the server will respond with complete XML data. In particular, the client will send complete XML documents to
documents containing <rpc-reply> elements. The client MAY indicate the server containing <rpc> elements, and the server will respond
interest in receiving event notifications from a NETCONF server by with complete XML documents containing <rpc-reply> elements. The
creating a subscription to receive event notifications [RFC5277], in client MAY indicate interest in receiving event notifications from a
which the NETCONF server replies to indicate whether the subscription server by creating a subscription to receive event notifications
request was successful and, if it was successful, begins sending the [RFC5277], in which the server replies to indicate whether the
event notifications to the NETCONF client as the events occur within subscription request was successful and, if it was successful, begins
the system. All these elements are encapsulated into TLS records of sending the event notifications to the client as the events occur
type "application data". These records are protected using the TLS within the system.
material keys.
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 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 Implementation of the protocol specified in this document MAY
implement any TLS cipher suite that provides certificate-based mutual
authentication [RFC5246].
Either NETCONF peer MAY stop the NETCONF connection at any time and Implementations MUST support TLS 1.2 [RFC5246] and are REQUIRED to
therefore notify the other NETCONF peer that no more data on this support the mandatory to implement cipher suite, which is
channel will be sent and that any data received after a closure TLS_RSA_WITH_AES_128_CBC_SHA. This document is assumed to apply to
request will be ignored. This MAY happen when no data is received future versions of TLS, in which case the mandatory to implement
from a connection for a long time, where the application decides what cipher suite for the implemented version MUST be supported.
"long" means.
TLS has the ability for secure connection closure using the Alert 2.2. Connection Closure
protocol. When the NETCONF peer closes the NETCONF connection, it
MUST send a TLS close_notify alert before closing the TCP connection.
Any data received after a closure alert is ignored.
Unless a fatal error has occurred, each party is required to send a A TLS client (NETCONF manager) MUST close the associated TLS
close_notify alert before closing the write side of the connection connection if the connection is not expected to issues any NETCONF
[RFC5246]. The other party MUST respond with a close_notify alert of RPC commands later. It MUST send a TLS close_notify alert before
its own and close down the connection immediately, discarding any closing the connection. The TLS client MAY choose to not wait for
pending writes. It is not required for the initiator of the close to the TLS server (NETCONF agent) close_notify alert and simply close
wait for the responding close_notify alert before closing the read the connection, thus generating an incomplete close on the TLS server
side of the connection. 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).
3. Endpoint Authentication and Identification 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.
NETCONF requires that its transport provide mutual authentication of 3. Endpoint Authentication and Identification
client and server, so cipher suites that are anonymous or which only
authenticate the server to the client MUST NOT be used with NETCONF.
This document specifies how to use TLS with endpoint authentication,
which can be based on either preshared keys [RFC4279] or public key
certificates [RFC5246]. Some cipher suites (e.g.
TLS_RSA_PSK_WITH_AES_128_CBC_SHA) use both. Section 3.1 describes
how the client authenticates the server if public key certificates
are provided by the server, section 3.2 describes how the server
authenticates the client if public key certificates are provided by
the client, and section 3.3 describes how the client and server
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.
Matching is performed according to these rules [RFC4642]: Matching is performed according to the rules below (following the
example of [RFC4642]):
- The client MUST use the server hostname it used to open the - The client MUST use the server hostname it used to open the
connection (or the hostname specified in TLS "server_name" connection (or the hostname specified in TLS "server_name"
extension [RFC4366]) as the value to compare against the server extension [RFC4366]) as the value to compare against the server
name as expressed in the server certificate. The client MUST name as expressed in the server certificate. The client MUST
NOT use any form of the server hostname derived from an NOT use any form of the server hostname derived from an
insecure remote source (e.g., insecure DNS lookup). CNAME insecure remote source (e.g., insecure DNS lookup). CNAME
canonicalization is not done. canonicalization is not done.
- If a subjectAltName extension of type dNSName is present in the - If a subjectAltName extension of type dNSName is present in the
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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. Pre-shared key Authentication 4. Security Considerations
[RFC4279] supports authentication based on pre-shared keys (PSKs).
These pre-shared keys are symmetric keys, shared in advance among the
communicating parties.
The PSK can be generated in many ways and its length is variable. It
is RECOMMENDED that implementations that allow the administrator to
manually configure the PSK also provide functionality for generating
a new random PSK, taking [RFC4086] into account.
If both the client and the server agree on using the pre-shared key
authentication, the server can provide a "PSK identity hint" in the
ServerKeyExchange message. If a hint is provided, 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
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.
If the string the user enters differs from the one returned as
psk_identity_hint, the software could display the server's name and
ask the user to confirm. For automated scripts, the names could be
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 TLS server).
It is RECOMMENDED that users choose different PSKs for the different
servers they manage.
[RFC4279] defines some conformance requirements for the PSK, for the
PSK identity encoding and for the identity hint. Moreover, it
describes the management interface requirements for entering the PSK
and/or PSK identity (See Section 5 of [RFC4279] for a more detailed
description of these requirements). Those same requirements apply
here as well.
4. Cipher Suite Requirements
A compliant implementation of the protocol specified in this document
MUST implement the cipher suite TLS_DHE_PSK_WITH_AES_128_CBC_SHA and
MAY implement any TLS cipher suite that provides mutual
authentication.
5. Security Considerations
The security considerations described throughout [RFC5246] and The security considerations described throughout [RFC5246] apply here
[RFC4279] apply here as well. 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, special care should be 5. IANA Considerations
taken to protect the shared secret as well as to limit its exposure
over time. Alternatively, using certificates would provide better
protection.
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 in the "Registered Port
default port for NETCONF over TLS sessions as defined in this Numbers" range with the name "netconf-tls". This port will be the
document. default port for NETCONF over TLS, as defined in this document.
IANA has assigned port <TBA> for this purpose. Registration Contact: Mohamad Badra, badra@isima.fr.
Transport Protocol: TCP.
Port Number: TBA-by-IANA (if possible, please assign 6513).
Broadcast, Multicast or Anycast: Anycast.
Port Name: netconf-tls.
Service Name: netconf.
Reference: draft-ietf-netconf-tls-05.
7. Acknowledgments 6. Acknowledgments
A significant amount of the text in Section 3.1 was lifted from A significant amount of the text in Section 3 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, Pasi Eronen and Tim Polk for the thorough review and Charlie Kaufman, Pasi Eronen and Tim Polk for the thorough review
of this document. of this document.
8. References 7. References
8.1. Normative References 7.1. 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.
[RFC4086] Eastlake, D., 3rd, Schiller, J., and S. Crocker,
"Randomness Requirements for Security", BCP 106, RFC 4086,
June 2005.
[RFC4279] Eronen, P. and H. Tschofenig., "Pre-Shared Key Ciphersuites
for Transport Layer Security (TLS)", RFC 4279, December
2005.
[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.
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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: Ibrahim.hajjeh@ineovation.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
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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
copyrights, patents or patent applications, or other proprietary copyrights, patents or patent applications, or other proprietary
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.
Acknowledgment
Funding for the RFC Editor function is provided by the IETF
Administrative Support Activity (IASA).
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