Internet-Draft NETCONF over TLS 1.3 June 2022
Turner & Housley Expires 19 December 2022 [Page]
Network Configuration
Intended Status:
Standards Track
S. Turner
R. Housley
Vigil Security

NETCONF over TLS 1.3


RFC 7589 defines how to protect NETCONF messages with TLS 1.2. This document describes how to protect NETCONF messages with TLS 1.3.

Discussion Venues

This note is to be removed before publishing as an RFC.

Discussion of this document takes place on the Network Configuration Working Group mailing list (, which is archived at

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Status of This Memo

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This Internet-Draft will expire on 19 December 2022.

Table of Contents

1. Introduction

[RFC7589] defines how to protect NETCONF messages [RFC6241] with TLS 1.2 [RFC5246]. This document describes defines how to protect NETCONF messages with TLS 1.3 [I-D.ietf-tls-rfc8446bis].

This document addresses cipher suites and the use of early data, which is also known as 0-RTT data. It also updates the "netconf-tls" IANA Registered Port Number entry to refer to this document. All other provisions set forth in [RFC7589] are unchanged, including connection initiation, message framing, connection closure, certificate validation, server identity, and client identity.

2. Conventions and Definitions

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

3. Early Data

Early data (aka 0-RTT data) is a mechanism defined in TLS 1.3 [I-D.ietf-tls-rfc8446bis] that allows a client to send data ("early data") as part of the first flight of messages to a server. Early data is permitted by TLS 1.3 when the client and server share a PSK, either obtained externally or via a previous handshake. The client uses the PSK to authenticate the server and to encrypt the early data.

As noted in Section 2.3 of [I-D.ietf-tls-rfc8446bis], the security properties for early data are weaker than those for subsequent TLS-protected data. In particular, early data is not forward secret, and there are no protection against the replay of early data between connections. Appendix E.5 of [I-D.ietf-tls-rfc8446bis] requires applicaitons not use early data without a profile that defines its use. This document specifies that implementations MUST NOT use early data.

4. Cipher Suites

Implementations MUST support TLS 1.3 [I-D.ietf-tls-rfc8446bis], and implementation are REQUIRED to support the mandatory-to-implement cipher suites listed in Section 9.1 of [I-D.ietf-tls-rfc8446bis].

Implementations MAY implement additional TLS cipher suites that provide mutual authentication and confidentiality, which are required for NETCONF [RFC6241].

Implementations SHOULD follow the recommendations given in [I-D.ietf-uta-rfc7525bis].

So, this is what {{Section 9.1 of I-D.ietf-tls-rfc8446bis}} says:

  A TLS-compliant application MUST implement the TLS_AES_128_GCM_SHA256
  [GCM] cipher suite and SHOULD implement the TLS_AES_256_GCM_SHA384
  [GCM] and TLS_CHACHA20_POLY1305_SHA256 [RFC8439] cipher suites (see
  Appendix B.4).

  A TLS-compliant application MUST support digital signatures with
  rsa_pkcs1_sha256 (for certificates), rsa_pss_rsae_sha256 (for
  CertificateVerify and certificates), and ecdsa_secp256r1_sha256.  A
  TLS-compliant application MUST support key exchange with secp256r1
  (NIST P-256) and SHOULD support key exchange with X25519 [RFC7748].

Is there any reason to narrow the algorithm choices?

My guess is not.  These ought to be available in all TLS libraries.

5. Security Considerations

Please review the Security Considerations in TLS 1.3 [I-D.ietf-tls-rfc8446bis].

Please review the recommendations regarding Diffie-Hellman exponent reuse in Section 7.4 of [I-D.ietf-uta-rfc7525bis].

Please review the Security Considerations in NETCONF [RFC6241].

NETCONF is used to access configuration and state information and to modify configuration information. TLS 1.3 mutual authentication is used to ensure that only authorized users and systems are able to view the NETCONF server's configuration and state or to modify the NETCONF server's configuration. To this end, neither the client nor the server should establish a NETCONF over TLS 1.3 connection with an unknown, unexpected, or incorrect peer identity; see Section 7 of [RFC7589]. If deployments make use of this list of Certification Authority (CA) certificates [RFC5280], then the listed CAs should only issue certificates to parties that are authorized to access the NETCONF servers. Doing otherwise will allow certificates that were issued for other purposes to be inappropriately accepted by a NETCONF server.

Please review [RFC6125] for further details on generic host name validation in the TLS context.

Please review the recommendations regarding certificate revocation checking in Section 7.5 of [I-D.ietf-uta-rfc7525bis].

[RFC5539] 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. While it is possible, the likelihood is believed to be very low. The EOM sequence is used for the initial <hello> message to avoid incompatibility with existing implementations. When the client and server both implement the :base:1.1 capability, a proper framing protocol (see Section 3 of [RFC7589]) is used for the rest of the NETCONF session, to avoid injection attacks.

6. IANA Considerations

IANA is requested to add a reference to this document in the "netconf-tls" entry in the "Registered Port Numbers". The updated registry entry would appear as follows:

 Service Name:           netconf-tls
 Transport Protocol(s):  TCP
 Assignee:               IESG <>
 Contact:                IETF Chair <>
 Description:            NETCONF over TLS
 Reference:              RFC 7589, [THIS RFC]
 Port Number:            6513

7. References

7.1. Normative References

Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", Work in Progress, Internet-Draft, draft-ietf-tls-rfc8446bis-04, , <>.
Sheffer, Y., Saint-Andre, P., and T. Fossati, "Recommendations for Secure Use of Transport Layer Security (TLS) and Datagram Transport Layer Security (DTLS)", Work in Progress, Internet-Draft, draft-ietf-uta-rfc7525bis-07, , <>.
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <>.
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, DOI 10.17487/RFC5280, , <>.
Badra, M., "NETCONF over Transport Layer Security (TLS)", RFC 5539, DOI 10.17487/RFC5539, , <>.
Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, , <>.
Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication", RFC 7589, DOI 10.17487/RFC7589, , <>.
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <>.

7.2. Informative References

Dierks, T. and E. Rescorla, "The Transport Layer Security (TLS) Protocol Version 1.2", RFC 5246, DOI 10.17487/RFC5246, , <>.
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, DOI 10.17487/RFC6125, , <>.


We would like to thank the following people TBD.

Authors' Addresses

Sean Turner
Russ Housley
Vigil Security, LLC
516 Dranesville Road
Herndon, VA, 20170
United States of America