Updates to Using the NETCONF Protocol over Transport Layer Security (TLS) with Mutual X.509 Authentication

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Table of Contents

1. Introduction

[RFC7589] defines how to protect NETCONF messages [RFC6241] with TLS 1.2 [RFC5246]. This document updates [RFC7589] to address support requirements for TLS 1.2 [RFC5246] and TLS 1.3 [I-D.ietf-tls-rfc8446bis] and the use of TLS 1.3's 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. Note that TLS 1.3 can be used without early data as per Appendix F.5 of [I-D.ietf-tls-rfc8446bis]. In fact, early data is permitted by TLS 1.3 only when the client and server share a Pre-Shared Key (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 is no protection against the replay of early data between connections. Appendix E.5 of [I-D.ietf-tls-rfc8446bis] requires applications not use early data without a profile that defines its use. This document specifies that NETCONF implementations that support TLS 1.3 MUST NOT use early data.¶

4. Cipher Suites

Implementations MUST support TLS 1.2 [RFC5246] and are REQUIRED to support the TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 cipher suite [RFC9325].¶

Implementations MAY implement additional TLS 1.2 cipher suites that provide mutual authentication [RFC5246] and confidentiality as required by NETCONF [RFC6241].¶

Implementations SHOULD support TLS 1.3 [I-D.ietf-tls-rfc8446bis] and, if implemented, MUST prefer to negotiate TLS 1.3 over earlier versions of TLS.¶

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

Implementations that support TLS 1.3 MAY implement additional TLS cipher suites that provide mutual authentication and confidentiality, which are required for NETCONF [RFC6241].¶

NETCONF implementations SHOULD follow the recommendations given in [RFC9325].¶

5. Security Considerations

The Security Considerations of [RFC6241], [RFC7589], and [RFC9325] apply here as well.¶

For implementations that support TLS 1.3, the Security Considerations of TLS 1.3 [I-D.ietf-tls-rfc8446bis] apply.¶

The following considerations from [RFC7589] has been modified to also apply to TLS 1.3 [I-D.ietf-tls-rfc8446bis]:¶

• 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 incorrectly identified peer; see Section 7 of [RFC7589]. If deployments make use of a trusted 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.¶

The Security Considerations of [I-D.ietf-uta-rfc6125bis] apply to all implementations when the client checks the identity of the server, as is required in Section 6 of [RFC7589].¶

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 <iesg@ietf.org>
 Contact:                IETF Chair <chair@ietf.org>
 Description:            NETCONF over TLS
 Reference:              RFC 7589, [THIS RFC]
 Port Number:            6513

Acknowledgments

We would like to thank Per Andersson, Jürgen Schönwälder, Jeff Hartley, and Qin Wu for their reviews.¶

Authors' Addresses