Using the NETCONF Protocol over Transport Layer Security (TLS)
draft-ietf-netconf-rfc5539bis-06
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft that was ultimately published as RFC 7589.
|
|
|---|---|---|---|
| Authors | Mohamad Badra , Alan Luchuk , Jürgen Schönwälder | ||
| Last updated | 2014-09-30 | ||
| Replaces | draft-badra-netconf-rfc5539bis | ||
| RFC stream | Internet Engineering Task Force (IETF) | ||
| Formats | |||
| Reviews | |||
| Additional resources | Mailing list discussion | ||
| Stream | WG state | WG Document | |
| Document shepherd | (None) | ||
| IESG | IESG state | Became RFC 7589 (Proposed Standard) | |
| Consensus boilerplate | Unknown | ||
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-ietf-netconf-rfc5539bis-06
NETCONF Working Group M. Badra
Internet-Draft Zayed University
Obsoletes: 5539 (if approved) A. Luchuk
Intended status: Standards Track SNMP Research, Inc.
Expires: April 3, 2015 J. Schoenwaelder
Jacobs University Bremen
September 30, 2014
Using the NETCONF Protocol over Transport Layer Security (TLS)
draft-ietf-netconf-rfc5539bis-06
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 the exchange of NETCONF messages. This revision
of RFC 5539 documents the new message framing for NETCONF 1.1 and it
obsoletes RFC 5539.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 3, 2015.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
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to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. NETCONF over TLS . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Connection Initiation . . . . . . . . . . . . . . . . . . 3
2.2. Message Framing . . . . . . . . . . . . . . . . . . . . . 3
2.3. Connection Closure . . . . . . . . . . . . . . . . . . . 4
2.4. X.509-based Authentication, Identification and
Authorization . . . . . . . . . . . . . . . . . . . . . . 4
2.4.1. Server Identity . . . . . . . . . . . . . . . . . . . 4
2.4.2. Client Identity . . . . . . . . . . . . . . . . . . . 4
2.4.3. Deriving NETCONF Usernames from X.509 Certificates . 5
2.5. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . 5
3. Security Considerations . . . . . . . . . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. Contributor's Address . . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Changes from RFC 5539 . . . . . . . . . . . . . . . 8
Appendix B. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 8
B.1. draft-ietf-netconf-rfc5539bis-06 . . . . . . . . . . . . 8
B.2. draft-ietf-netconf-rfc5539bis-05 . . . . . . . . . . . . 8
B.3. draft-ietf-netconf-rfc5539bis-04 . . . . . . . . . . . . 8
B.4. draft-ietf-netconf-rfc5539bis-03 . . . . . . . . . . . . 9
B.5. draft-ietf-netconf-rfc5539bis-02 . . . . . . . . . . . . 9
B.6. draft-ietf-netconf-rfc5539bis-00 . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
The NETCONF protocol [RFC6241] 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 integrity, confidentiality, peer authentication, and
reliable, sequenced data delivery.
This document defines how NETCONF messages can be exchanged over
Transport Layer Security (TLS) [RFC5246]. The TLS protocol provides
support for certificate-based mutual authentication, key derivation,
protected ciphersuite negotiation, and key management capabilities.
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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 [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 client MUST act as the TLS client.
The TLS client actively opens the TLS connection and the TLS server
passively listens for the incoming TLS connection on the TCP port
6513. The TLS client 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 messages. Client
and server identity verification (as described in Section 2.4) is
done before the <hello> message is sent. This means that the
identity verification is completed before the NETCONF session has
started.
The well-known port number 6513 is used by NETCONF servers to listen
for connections established by NETCONF clients. NETCONF clients
connect to the server on the server port 6513 in order to send
NETCONF messages to the NETCONF server.
2.2. Message Framing
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.
The previous version [RFC5539] of this document used the framing
sequence defined in [RFC4742], under the assumption that it could not
be found in well-formed XML documents. However, this assumption is
not correct [RFC6242]. In order to solve this problem, this document
adopts the framing protocol defined in [RFC6242] as follows:
The <hello> message MUST be followed by the character sequence
]]>]]>. Upon reception of the <hello> message, the peers inspect the
announced capabilities. If the :base:1.1 capability is advertised by
both peers, the chunked framing mechanism defined in Section 4.2 of
[RFC6242] is used for the remainder of the NETCONF session.
Otherwise, the old end-of-message-based mechanism (see Section 4.3 of
[RFC6242]) is used.
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2.3. Connection Closure
A NETCONF server will process NETCONF messages from the NETCONF
client in the order in which they are received. A NETCONF session is
closed using the <close-session> operation. When the NETCONF server
processes a <close-session> operation, the NETCONF server SHALL
respond and close the TLS session as described in Section 7.2.1 of
[RFC5246].
2.4. X.509-based Authentication, Identification and Authorization
Implementations MAY optionally support TLS certificate-based
authentication [RFC5246]. If the implementation supports TLS
certificate-based authentication, then the following sections apply.
2.4.1. Server Identity
If the certificate presented by a NETCONF server has passed
certification path validation [RFC5280] to a configured trust anchor,
the NETCONF client MUST carefully examine the certificate presented
by the server to determine if it meets the client's expectations. If
the NETCONF client has external information as to the expected
identity of the NETCONF server, the hostname check MAY be omitted.
Otherwise, the NETCONF client MUST check its understanding of the
NETCONF 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 and guidelines defined
in [RFC6125]. If the match fails, the NETCONF client MUST either ask
for explicit user confirmation or terminate the connection and
indicate the NETCONF server's identity is suspect.
Additionally, NETCONF clients MUST verify the binding between the
identity of the NETCONF servers to which they connect and the public
keys presented by those servers. NETCONF 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 NETCONF server certificate against a local store of
already-verified certificates and identity bindings).
2.4.2. Client Identity
The NETCONF server MUST verify the identity of the NETCONF client to
ensure that the incoming request to establish a NETCONF session is
legitimate before the NETCONF session is started.
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The NETCONF protocol [RFC6241] requires that the transport protocol's
authentication process MUST result in an authenticated NETCONF client
identity whose permissions are known to the server. The
authenticated identity of a client is commonly referred to as the
NETCONF username.
The username provided by the NETCONF over TLS implementation will be
made available to the NETCONF message layer as the NETCONF username
without modification. If the username does not comply to the NETCONF
requirements on usernames [RFC6241], i.e., the username is not
representable in XML, the TLS session MUST be dropped.
2.4.3. Deriving NETCONF Usernames from X.509 Certificates
After completing the TLS handshake, the NETCONF server attempts to
derive a NETCONF username from the X.509 certificate presented by the
NETCONF client. If the NETCONF server cannot derive a valid NETCONF
username from the presented certificate, then the NETCONF server MUST
close the TLS connection, and MUST NOT accept NETCONF messages over
it. The NETCONF server uses the algorithm defined in
[I-D.ietf-netconf-server-model] to extract a NETCONF username from
the X.509 certificate presented by the NETCONF client.
2.5. Cipher Suites
Implementations of the protocol specified in this document MAY
implement any TLS cipher suite that provides mutual authentication
[RFC5246]. However, implementations MUST support TLS 1.2 [RFC5246]
and are REQUIRED to support the mandatory-to-implement cipher suite.
3. Security Considerations
NETCONF is used to access configuration and state information and to
modify configuration information, so the ability to access this
protocol should be limited to users and systems that are authorized
to view the NETCONF server's configuration and state or to modify the
NETCONF server's configuration.
Configuration or state data may include sensitive information, such
as usernames or security keys. So, NETCONF requires communications
channels that provide strong encryption for data privacy. This
document defines a NETCONF over TLS mapping that provides for support
of strong encryption and authentication. The security considerations
for TLS [RFC5246] and NETCONF [RFC6241] apply here as well.
NETCONF over TLS requires mutual authentication. Neither side should
establish a NETCONF over SSH connection with an unknown, unexpected,
or incorrect identity on the opposite side. This document does not
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support third-party authentication (e.g., backend Authentication,
Authorization, and Accounting (AAA) servers) due to the fact that TLS
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, the SSH transport can be used.
RFC 5539 assumes that the end-of-message (EOM) sequence, ]]>]]>,
cannot appear in any well-formed XML document, which turned out to be
mistaken. The EOM sequence can cause operational problems and open
space for attacks if sent deliberately in NETCONF messages. It is
however believed that the associated threat is not very high. This
document still uses the EOM sequence for the initial <hello> message
to avoid incompatibility with existing implementations. When both
peers implement base:1.1 capability, a proper framing protocol
(chunked framing mechanism; see Section 2.2) is used for the rest of
the NETCONF session, to avoid injection attacks.
4. IANA Considerations
Based on the previous version of this document, RFC 5539, IANA has
assigned a TCP port number (6513) in the "Registered Port Numbers"
range with the service name "netconf-tls". This port will be the
default port for NETCONF over TLS, as defined in Section 2.1. Below
is the registration template following the rules in [RFC6335].
Service Name: netconf-tls
Transport Protocol(s): TCP
Assignee: IESG <iesg@ietf.org>
Contact: IETF Chair <chair@ietf.org>
Description: NETCONF over TLS
Reference: RFC XXXX
Port Number: 6513
5. Acknowledgements
The authors like to acknowledge Martin Bjorklund, Olivier Coupelon,
Mehmet Ersue, Miao Fuyou, David Harrington, Alfred Hoenes, Simon
Josefsson, Eric Rescorla, Dan Romascanu, Kent Watsen, Bert Wijnen and
the NETCONF mailing list members for their comments on this document.
Charlie Kaufman, Pasi Eronen, and Tim Polk provided a thorough review
of previous versions of this document.
Juergen Schoenwaelder was partly funded by Flamingo, a Network of
Excellence project (ICT-318488) supported by the European Commission
under its Seventh Framework Programme.
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6. Contributor's Address
Ibrahim Hajjeh
Ineovation
France
EMail: ibrahim.hajjeh@ineovation.fr
7. References
7.1. Normative References
[I-D.ietf-netconf-server-model]
Watsen, K. and J. Schoenwaelder, "NETCONF Server
Configuration Model", draft-ietf-netconf-server-model-03
(work in progress), September 2014.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 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.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, March 2011.
[RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
Bierman, "Network Configuration Protocol (NETCONF)", RFC
6241, June 2011.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, June 2011.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165, RFC
6335, August 2011.
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7.2. Informative References
[RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF
Configuration Protocol over Secure SHell (SSH)", RFC 4742,
December 2006.
[RFC5539] Badra, M., "NETCONF over Transport Layer Security (TLS)",
RFC 5539, May 2009.
Appendix A. Changes from RFC 5539
This section lists major changes between this document and RFC 5539.
o Documented that NETCONF uses the new message framing if both peers
support the base:1.1 capability.
o Removed redundant text that can be found in the TLS and NETCONF
specifications.
o Merged sections 2 and 3 into a new section 2 and restructured the
text.
o Removed the reference to BEEP.
Appendix B. Change Log (to be removed by RFC Editor before publication)
B.1. draft-ietf-netconf-rfc5539bis-06
o Removed all call-home related text.
o Removed redundant text as discussed at the Toronto IETF meeting.
B.2. draft-ietf-netconf-rfc5539bis-05
o Removed the YANG configuration data model since it became a
separate document.
o Added reference to RFC 3234 plus editorial updates.
B.3. draft-ietf-netconf-rfc5539bis-04
o Added the applicability statement proposed by Stephen Hanna.
o Added call-home configuration objects and a tls-call-home feature.
o Rewrote the text such that the role swap happens right after the
TCP connection has been established.
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B.4. draft-ietf-netconf-rfc5539bis-03
o Added support for call home (allocation of a new port number,
rewrote text to allow a NETCONF client to be a TLS server and a
NETCONF server to be a TLS client).
o Merged sections 2 and 3 into a new section 2 and restructured the
text.
o Extended the IANA considerations section.
o Using the cert-to-name mapping grouping from the SNMP
configuration data model and updated the examples.
o Creating an extensible set of YANG (sub)modules for NETCONF
following the (sub)module structure of the SNMP configuration
model.
B.5. draft-ietf-netconf-rfc5539bis-02
o Addressed remaining issues identified at IETF 85
* Harmonized the cert-maps container of the YANG module in this
draft with the tlstm container in the ietf-snmp-tls sub-module
specified in draft-ietf-netmod-snmp-cfg. Replaced the children
of the cert-maps container with the children copied from the
tlstm container of the ietf-snmp-tls sub-module.
* Added an overview of data model in the ietf-netconf-tls YANG
module.
* Added example configurations.
o Addessed issues posted on NETCONF WG E-mail list.
o Deleted the superfluous tls container that was directly below the
netconf-config container.
o Added a statement to the text indicating that support for mapping
X.509 certificates to NETCONF usernames is optional. This is
analogous to existing text indicating that support for mapping
pre-shared keys to NETCONF usernames is optional. Resource-
constrained systems now can omit support for mapping X.509
certificates to NETCONF usernames and still comply with this
specification.
o Clarified the document structure by promoting the sections of the
document related to the data model.
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o Updated author's addresses.
B.6. draft-ietf-netconf-rfc5539bis-00
o Remove the reference to BEEP.
o Rename host-part to domain-part in the description of RFC822.
Authors' Addresses
Mohamad Badra
Zayed University
Email: mbadra@gmail.com
Alan Luchuk
SNMP Research, Inc.
3001 Kimberlin Heights Road
Knoxville, TN 37920
USA
Phone: +1 865 573 1434
Email: luchuk@snmp.com
URI: http://www.snmp.com/
Juergen Schoenwaelder
Jacobs University Bremen
Campus Ring 1
28759 Bremen
Germany
Phone: +49 421 200 3587
Email: j.schoenwaelder@jacobs-university.de
URI: http://www.jacobs-university.de/
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