Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication
draft-ietf-netconf-rfc5539bis-07
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 | 2014-12-11 | ||
| 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-07
NETCONF Working Group M. Badra
Internet-Draft Zayed University
Obsoletes: 5539 (if approved) A. Luchuk
Intended status: Standards Track SNMP Research, Inc.
Expires: June 11, 2015 J. Schoenwaelder
Jacobs University Bremen
December 8, 2014
Using the NETCONF Protocol over Transport Layer Security (TLS) with
Mutual X.509 Authentication
draft-ietf-netconf-rfc5539bis-07
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 with mutual X.509 authentication to secure the exchange of
NETCONF messages. This revision of RFC 5539 documents the new
message framing used by 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 June 11, 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
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carefully, as they describe your rights and restrictions with respect
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. Connection Initiation . . . . . . . . . . . . . . . . . . . . 3
3. Message Framing . . . . . . . . . . . . . . . . . . . . . . . 3
4. Connection Closure . . . . . . . . . . . . . . . . . . . . . 3
5. Certificate Validation . . . . . . . . . . . . . . . . . . . 4
6. Server Identity . . . . . . . . . . . . . . . . . . . . . . . 4
7. Client Identity . . . . . . . . . . . . . . . . . . . . . . . 4
8. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . 5
9. Security Considerations . . . . . . . . . . . . . . . . . . . 6
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7
12. Contributor's Address . . . . . . . . . . . . . . . . . . . . 7
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
13.1. Normative References . . . . . . . . . . . . . . . . . . 7
13.2. Informative References . . . . . . . . . . . . . . . . . 8
Appendix A. Changes from RFC 5539 . . . . . . . . . . . . . . . 8
Appendix B. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 9
B.1. draft-ietf-netconf-rfc5539bis-07 . . . . . . . . . . . . 9
B.2. draft-ietf-netconf-rfc5539bis-06 . . . . . . . . . . . . 9
B.3. draft-ietf-netconf-rfc5539bis-05 . . . . . . . . . . . . 9
B.4. draft-ietf-netconf-rfc5539bis-04 . . . . . . . . . . . . 9
B.5. draft-ietf-netconf-rfc5539bis-03 . . . . . . . . . . . . 9
B.6. draft-ietf-netconf-rfc5539bis-02 . . . . . . . . . . . . 10
B.7. 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]. Implementations MUST
support mutual TLS certificate-based authentication [RFC5246]. This
assures the NETCONF server of the identity of the principal who
wishes to manipulate the management information. It assures the
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NETCONF client of the identity of the server for which it wishes to
manipulate the management information.
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. 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 connections. The well-known
TCP port number 6513 is used by NETCONF servers to listen for TCP
connections established by NETCONF over TLS clients. The TLS client
MUST 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 is done before the NETCONF <hello> message is sent.
This means that the identity verification is completed before the
NETCONF session is started.
3. 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 NETCONF <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.
4. 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
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respond and close the TLS session as described in Section 7.2.1 of
[RFC5246].
5. Certificate Validation
Both peers use X.509 certificate path validation [RFC5280] to verify
the integrity of the certificate presented by the peer. presented
X.509 certificate may also be considered valid if it matches a
locally configured certificate fingerprint. If X.509 certificate
path validation fails and the presented X.509 certificate does not
match a locally configured certificate fingerprint, the connection
MUST be terminated as defined in [RFC5246].
6. Server Identity
The NETCONF client MUST carefully examine the certificate presented
by the NETCONF 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.
7. 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.
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 following algorithm is used by the NETCONF
server to derive a NETCONF username from a certificate:
The server maintains an ordered list of mappings of certificates
to names. The username is derived by considering each list entry
in order. The fingerprint member of a list entry determines
whether the list entry is a match:
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1. If the list entry's fingerprint value matches that of the
presented certificate, then consider the list entry as a
successful match.
2. If the list entry's fingerprint value matches that of a
locally held copy of a trusted CA certificate, and that CA
certificate was part of the CA certificate chain to the
presented certificate, then consider the list entry as a
successful match.
Once a matching list entry has been found, the map-type member of
the list entry is used to determine how the name associated with
the certificate should be determined. Possible options are:
A. The username is explicitly configured.
B. The subjectAltName's rfc822Name is mapped to a username.
C. The subjectAltName's dNSName is mapped to a username.
D. The subjectAltName's iPAddress is mapped to a username.
E. Any of the subjectAltName's rfc822Name, dNSName, iPAddress is
mapped to a username.
F. The certificate's CommonName is mapped to a username.
If it is impossible to determine a name from the cert-to-name list
entry's data combined with the data presented in the certificate,
then additional cert-to-name list entries MUST be searched looking
for another potential match.
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.
8. Cipher Suites
Implementations MUST support TLS 1.2 [RFC5246] and are REQUIRED to
support the mandatory-to-implement cipher suite. Implementations MAY
implement additional TLS cipher suites that provide mutual
authentication [RFC5246] and confidentiality as required by NETCONF
[RFC6241]. Implementations SHOULD follow the recommendations given
in [I-D.ietf-uta-tls-bcp].
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9. 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 TLS connection with an unknown, unexpected,
or incorrect identity on the opposite side. This document does not
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 3) is used for the rest of
the NETCONF session, to avoid injection attacks.
10. 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. Below is
the registration template following the rules in [RFC6335].
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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
11. Acknowledgements
The authors like to acknowledge Martin Bjorklund, Olivier Coupelon,
Mehmet Ersue, Miao Fuyou, David Harrington, Alfred Hoenes, Simon
Josefsson, Tom Petch, 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.
12. Contributor's Address
Ibrahim Hajjeh
Ineovation
France
EMail: ibrahim.hajjeh@ineovation.fr
13. References
13.1. Normative References
[I-D.ietf-uta-tls-bcp]
Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of TLS and DTLS", draft-
ietf-uta-tls-bcp-07 (work in progress), November 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.
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[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.
13.2. 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 and restructured the text.
o Added a high-level description how NETCONF usernames are extracted
from certificates.
o Removed the reference to BEEP.
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Appendix B. Change Log (to be removed by RFC Editor before publication)
B.1. draft-ietf-netconf-rfc5539bis-07
o Limited the scope of the document to TLS with mutual X.509
authentication.
o Added a high-level description how NETCONF usernames are extracted
from certificates.
o Editorial changes
B.2. draft-ietf-netconf-rfc5539bis-06
o Removed all call-home related text.
o Removed redundant text as discussed at the Toronto IETF meeting.
B.3. 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.4. 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.
B.5. 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.
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o Creating an extensible set of YANG (sub)modules for NETCONF
following the (sub)module structure of the SNMP configuration
model.
B.6. 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.
o Updated author's addresses.
B.7. 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
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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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