NETCONF Working Group                                           M. Badra
Internet-Draft                                          LIMOS Laboratory
Obsoletes: 5539 (if approved)                                  A. Luchuk
Intended status: Standards Track                     SNMP Research Research, Inc.
Expires: April August 25, 2013                                J. Schoenwaelder
                                                Jacobs University Bremen
                                                        October 22, 2012
                                                       February 21, 2013

     Using the NETCONF Over Protocol over Transport Layer Security (TLS)
                    draft-ietf-netconf-rfc5539bis-01
                    draft-ietf-netconf-rfc5539bis-02

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 NETCONF exchanges.  This document 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 August 25, 2013.

Copyright Notice

   Copyright (c) 2012 2013 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
   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 . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Conventions Used in This Document  . . . . . . . . . . . .  3
   2.  NETCONF over TLS . . . . . . . . . . . . . . . . . . . . . . .  3
     2.1.  Connection Initiation  . . . . . . . . . . . . . . . . . .  3
     2.2.  Connection Closure . . . . . . . . . . . . . . . . . . . .  4
   3.  Endpoint Authentication, Identification and Authorization  . .  4
     3.1.  Server Identity  . . . . . . . . . . . . . . . . . . . . .  4
     3.2.  Client Identity  . . . . . . . . . . . . . . . . . . . . .  5
       3.2.1.  Deriving NETCONF Usernames From NETCONF Client
               Certificates . . . . . . . . . . . . . . . . . . . . .  5
       3.2.2.  Deriving NETCONF Usernames From PSK identities Identities . . . .  7
       3.2.3.  Remote Configuration
   4.  Data Model . . . . . . . . . . . . . . . . . . . . . . . . . .  7
   4.
     4.1.  Data Model Overview  . . . . . . . . . . . . . . . . . . .  7
     4.2.  YANG Module  . . . . . . . . . . . . . . . . . . . . . . .  7
   5.  Usage Examples . . . . . . . . . . . . . . . . . . . . . . . . 15
     5.1.  Certificate Mapping Configuration Example  . . . . . . . . 15
     5.2.  PSK Mapping Configuration Example  . . . . . . . . . . . . 15
   6.  Security Considerations  . . . . . . . . . . . . . . . . . . . 14
   5. 15
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 15
   6. 16
   8.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 16
   7. 17
   9.  Contributor's Address  . . . . . . . . . . . . . . . . . . . . 16
   8. 17
   10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
     8.1. 17
     10.1. Normative References . . . . . . . . . . . . . . . . . . . 16
     8.2. 17
     10.2. Informative References . . . . . . . . . . . . . . . . . . 17 18
   Appendix A.  Change Log (to be removed by RFC Editor before
                publication)  . . . . . . . . . . . . . . . . . . . . 17 18
     A.1.  Open Issues  . . . . . . . . . . . . . . . . . . . . . . . 18
     A.2.  From draft-ietf-netconf-rfc5539bis-00 to draft-ietf-netconf-rfc5539bis-01 to
           draft-ietf-netconf-rfc5539bis-02 . . . . . . . . . . . . . 17
     A.2. 19
     A.3.  From draft-badra-netconf-rfc5539bis-02 to
           draft-ietf-netconf-rfc5539bis-00 . . . . . . . . . . . . . 17 19
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17 19

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 "NETCONF over TLS", which includes support for
   certificate and pre-shared key (PSK)-based 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].

1.1.  Conventions Used in This Document

   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 also 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.  It  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 data.  In particular,
   the client will send complete XML documents to the server containing
   <rpc> elements,
   messages.  Client and the server will respond with complete XML
   documents containing <rpc-reply> elements.  The client MAY indicate
   interest identity verification (as described in receiving event notifications from a server by creating a
   subscription to receive event notifications [RFC5277].  In this case,
   Section 3) is done before the server replies to indicate whether <hello> message is sent; for the subscription request was
   successful and, if it was successful,
   server, this means the server begins sending the
   event notifications to the client as the events occur within identity verification is completed before the
   system.
   NETCONF session has started.

   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 same framing
   sequence defined in [RFC6242], [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, and at the
   same time be compatible with existing implementations, this document
   uses the framing protocol defined in [RFC6242] as following:

   The <hello> message MUST be followed by the character sequence
   ]]>]]>.  Upon reception of the <hello> message, the receiving peer's
   TLS Transport layer conceptually passes the <hello> message to the
   Messages layer.  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.

   Implementation

   Implementations of the protocol specified in this document MAY
   implement any TLS cipher suite that provides mutual authentication
   [RFC5246].

   Implementations  However, implementations MUST support TLS 1.2 [RFC5246]
   and are REQUIRED to support the mandatory-to-implement cipher suite,
   which is TLS_RSA_WITH_AES_128_CBC_SHA.  This document is assumed to
   apply to future versions of TLS; in which case, the mandatory-to-implement mandatory-to-
   implement cipher suite for the implemented version MUST be supported.

2.2.  Connection Closure

   Exiting NETCONF is accomplished using the <close-session> operation.
   A NETCONF server will process NETCONF messages from the NETCONF
   client in the order in which they are received.  When the NETCONF
   server processes a <close-session> operation, the NETCONF server
   SHALL respond and close the TLS session channel. session.  The NETCONF server MUST NOT
   process any NETCONF messages received after the <close-
   session> <close-session>
   operation.  The TLS session is closed as described in
   [RFC6242] [RFC5246]
   Section 7.2.1.

3.  Endpoint 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.

3.1.  Server Identity

   If the server's presented certificate has passed certification path
   validation [RFC5280] to a configured trust anchor, the client MUST
   carefully examine the certificate presented by the server to
   determine if it meets the client's expectations.  Particularly, the
   client MUST check its understanding of the server hostname against
   the server's identity as presented in the server Certificate message,
   in order to prevent man- in-the-middle man-in-the-middle attacks.

   Matching is performed according to the rules and guidelines defined
   in [RFC6125].

   If the match fails, the client MUST either ask for explicit user
   confirmation or terminate the connection and indicate the server's
   identity is suspect.

   Additionally, clients MUST verify the binding between the identity of
   the servers to which they connect and the public keys presented by
   those servers.  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 server certificate
   against a local store of already-verified certificates and identity
   bindings).

   If the client has external information as to the expected identity of
   the server, the hostname check MAY be omitted.

3.2.  Client Identity

   The server MUST verify the identity of the client to ensure that the
   incoming client request 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 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 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.

   Algorithms for mapping certificates or PSK identities (sent by the
   client) to NETCONF usernames are described below.

3.2.1.  Deriving NETCONF Usernames From NETCONF Client Certificates

   The algorithm for deriving NETCONF usernames from TLS certificates is
   patterned after the algorithm for deriving tmSecurityNames from TLS
   certificates specified in the Transport Layer Security (TLS)
   Transport Model for the Simple Network Management Protocol (SNMP)
   [RFC6353].  The NETCONF server MUST implement the algorithms for
   deriving NETCONF usernames from presented certificates that are
   documented in the ietf-netconf-tls YANG module, defined in
   Section 3.2.3. 4.2.  This YANG module lets the NETCONF security
   administrator configure how the NETCONF server derives NETCONF
   usernames from presented certificates.  It also lets different
   certificate-to-username derivation algorithms be used for different
   certificates.

   When a NETCONF server accepts a TLS connection from a NETCONF client,
   the NETCONF server attempts to derive a NETCONF username from the
   certificate presented by the NETCONF client.  If the NETCONF server
   cannot derive a valid NETCONF username from the client's presented
   certificate, then the NETCONF server MUST close the TLS connection,
   and MUST NOT accept NETCONF messages over it.  The NETCONF server
   uses one of the following algorithms to produce a NETCONF username
   from the certificate presented by the NETCONF client:

   o  Map a certificate directly to a specified, pre-configured, NETCONF
      username;

   o  Extract the subjectAltName's rfc822Name from the certificate, then
      use the extracted rfc822Name as the NETCONF username;

   o  Extract the subjectAltName's dnsName from the certificate, then
      use the extracted dnsName as the NETCONF username;

   o  Extract the subjectAltName's iPAddress from the certificate, then
      use the extracted iPAddress as the NETCONF username;

   o  Examine the subjectAltName's rfc822Name, dnsName, and iPAddress
      fields in a pre-defined order.  Return the value from the first
      subjectAltName field that is examined, defined, and populated with
      a non-empty value.  If no subjectAltName field of a specific type
      is defined, then the examination skips that field and proceeds to
      examine the next field type.  If a subjectAltName field is
      defined, but the value is not populated, or is populated by an
      empty value, then the examination skips that field and proceeds to
      examine the next field type.

   The NETCONF server MUST implement all of these algorithms, and allow
   the deployer to choose the algorithm used.  The cert-map list in the
   ietf-netconf-tls YANG module specifies how a NETCONF server
   transforms a certificate into a NETCONF username.

   If the fingerprint of locally held copy of a trusted CA certificate
   is configured in the cert-map list in the ietf-netconf-tls YANG
   module, and that CA certificate is used to validate the certificate
   presented by the client, then the NETCONF server uses that cert-map
   list entry to produce the NETCONF username.  This allows multiple
   client certificates (all signed by the same trusted CA certificate)
   to be mapped to a NETCONF username by a single entry in the cert-map
   list.

3.2.2.  Deriving NETCONF Usernames From PSK identities Identities

   Implementations MAY optionally support TLS Pre-Shared Key (PSK)
   authentication [RFC4279].  RFC4279 describes pre-shared key
   ciphersuites for TLS.  The description of the psk-maps container in
   the ietf-netconf-tls YANG module, defined in section 3.2.3, Section 4.2, specifies
   how a NETCONF server transforms a TLS pre-shared key into a NETCONF
   username.

3.2.3.  Remote Configuration

4.  Data Model

4.1.  Data Model Overview

   The YANG module "ietf-netconf-tls", which defines configuration
   parameters for mapping TLS parameters to NETCONF usernames, has the
   following structure.  Square brackets are used to enclose a list's
   keys, and "?" means that the node is optional.  Choice and case nodes
   are enclosed in parenthesis, and a case node is marked with a colon
   (":").

   module: ietf-netconf-tls
      +--rw netconf-tls
         +--rw cert-maps
         |  +--rw cert-to-security-name [id]
         |     +--rw id                              uint32
         |     +--rw fingerprint                     tls-fingerprint
         |     +--rw map-type                        identityref
         |     +--rw cert-specified-security-name    nacm:user-name-type
         +--rw psk-maps
            +--rw psk-map [psk-identity]
               +--rw psk-identity        string
               +--rw user-name           nacm:user-name-type
               +--rw valid-not-before?   yang:date-and-time
               +--rw valid-not-after?    yang:date-and-time
               +--rw key                 string

4.2.  YANG Module

   The ietf-netconf-tls YANG module defines objects for remotely
   configuring the mapping of TLS certficates and of PSK Identities to
   NETCONF usernames.

   <CODE BEGINS> file "ietf-netconf-tls@2013-02-19.yang"

   module ietf-netconf-tls {

     namespace "urn:ietf:params:xml:ns:yang:ietf-netconf-tls";

     prefix "nctls";

     import ietf-yang-types {
       prefix yang;
     }

     import ietf-netconf-acm {
       prefix nacm;
     }

     organization
      "IETF NETCONF (Network Configuration) Working Group";

     contact
      "WG Web:   <http://tools.ietf.org/wg/netconf/>
       WG List:  <mailto:netconf@ietf.org>

       WG Chair: Mehmet Ersue
                 <mailto:mehmet.ersue@nsn.com>

       WG Chair: Bert Wijnen
                 <mailto:bertietf@bwijnen.net>

       Editor:   Mohamad Badra
             <mailto:mbadra@gmail.com>";
                 <mailto:mbadra@gmail.com>

                 Alan Luchuk
                 <mailto:luchuk@snmp.com>

                 Juergen Schoenwaelder
                 <mailto:j.schoenwaelder@jacobs-university.de>";

     description
      "This module applies to NETCONF over TLS.  It specifies how
       NETCONF servers transform X.509 certificates presented by clients
       into NETCONF usernames.  It also specifies how NETCONF servers
       transform pre-shared TLS keys into NETCONF usernames.

       The cert-maps container in this YANG module is patterned after
       parts of the SNMP-TLS-TM-MIB defined in RFC 6353.  Much of the
       description text has been copied directly from the
       SNMP-TLS-TM-MIB, and modified as necessary.

       Copyright (c) 2012 2013 IETF Trust and the persons identified as
       authors of the code. All rights reserved.

       Redistribution and use in source and binary forms, with or
       without modification, is permitted pursuant to, and subject
       to the license terms contained in, the Simplified BSD
       License set forth in Section 4.c of the IETF Trust's
       Legal Provisions Relating to IETF Documents
       (http://trustee.ietf.org/license-info).

       This version of this YANG module is part of RFC XXXX; see
       the RFC itself for full legal notices.";
     // RFC Ed.: replace XXXX with actual RFC number and
     // remove this note

     // RFC Ed.: please update the date to the date of publication

     revision "2012-02-13" "2013-02-19" {
       description
        "Initial version";
       reference
        "RFC XXXX: NETCONF over Transport Layer Security (TLS)";
     }

     feature map-certificates {
       description
        "The map-certificates feature indicates that the server
         implements mapping X.509 certificates to NETCONF user names.";
     }

     feature map-pre-shared-keys {
       description
        "The map-pre-shared-keys feature indicates that the server
         implements mapping TLS pre-shared keys to NETCONF user names.";
     }

     // [DISCUSS] This definition of tls-fingerprint is the same as
     //           the one in draft-ietf-netmod-snmp-cfg-01.txt; can
     //           we avoid this duplication?

     typedef tls-fingerprint-type tls-fingerprint {
       type string yang:hex-string {
         pattern '([0-9a-fA-F]){2}(:([0-9a-fA-F]){2})*'; '([0-9a-fA-F]){2}(:([0-9a-fA-F]){2}){0,254}';
       }
       description
        "A cryptographic signature (fingerprint) fingerprint value that can be used to uniquely reference
         other data of potentially arbitrary length."; length.

         An tls-fingerprint value is composed of a 1-octet hashing
         algorithm identifier followed by the fingerprint value.  The
         octet value encoded is taken from the IANA TLS HashAlgorithm
         Registry (RFC 5246).  The remaining octets are filled using
         the results of the hashing algorithm.

         The corresponding TEXTUAL-CONVENTION allows a zero-length
         value to be used for objects that are optional.  In the YANG
         data models, such objects are represented as optional leafs.";
       reference "SNMP-TLS-TM-MIB.SnmpTLSFingerprint";
     }

 container netconf-config

     /* Identities */

     // [DISCUSS] The definitions of identities is the same as
     //           the those in draft-ietf-netmod-snmp-cfg-01.txt; can
     //           we avoid this duplication?

     identity cert-to-tm-security-name {
     }

     identity specified {
       base cert-to-tm-security-name;
       reference "SNMP-TLS-TM-MIB.snmpTlstmCertSpecified";
     }

     identity san-rfc822-name {
       base cert-to-tm-security-name;
       reference "SNMP-TLS-TM-MIB.snmpTlstmCertSANRFC822Name";
     }

     identity san-dns-name {
       base cert-to-tm-security-name;
       reference "SNMP-TLS-TM-MIB.snmpTlstmCertSANDNSName";
     }

     identity san-ip-address {
       base cert-to-tm-security-name;
       reference "SNMP-TLS-TM-MIB.snmpTlstmCertSANIpAddress";
     }

     identity san-any {
       base cert-to-tm-security-name;
       reference "SNMP-TLS-TM-MIB.snmpTlstmCertSANAny";
     }

     identity common-name {
       base cert-to-tm-security-name;
       reference "SNMP-TLS-TM-MIB.snmpTlstmCertCommonName";
     }

     container tls netconf-tls {

       //
 // Objects related to deriving NETCONF usernames from X.509
       // certificates.
 //

       container cert-maps {
         if-feature map-certificates;
    config true;
         description
          "The cert-maps container is used by a NETCONF server to
           map the NETCONF client's presented X.509 certificate to
           a NETCONF username.

           On an incoming TLS connection, the client's presented
           certificate MUST either be validated based on an established
           trust anchor, or it MUST directly match a fingerprint in the
           'cert-map' list.  This module does not provide any mechanisms
           for configuring the trust anchors; the transfer of any needed
           trusted certificates for certificate chain validation is
           expected to occur through an out-of-band transfer.

           Once the certificate has been found acceptable (either by
           certificate chain validation or directly matching a
           fingerprint in the cert-map list), the cert-map list is
           consulted to determine the appropriate NETCONF username to
           associate with the remote connection.  This is done by
           considering each cert-map cert-to-security-name list entry in order.
           The cert-map cert-to-security-name entry's fingerprint determines
           whether the list entry is a match for the incoming
           connection:

           1) If the cert-map cert-to-security-name list entry's fingerprint
              value matches that of the presented certificate, then
              consider the list entry as a successful match.

           2) If the cert-map cert-to-security-name 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 cert-map cert-to-security-name list entry has been
           found, the NETCONF server uses the map-type list to determine how
           the NETCONF username associated with the session should be
           determined.  See the map-
       type map-type leaf's description for details
           on determining the NETCONF username value.  If it is
           impossible to determine a NETCONF username from the cert-map
           cert-to-security-name list entry's data combined with the
           data presented in the certificate, then additional cert-map
           cert-to-tm-security-name list entries MUST be searched
           looking for another potential match.  If a resulting
           NETCONF username mapped from a given cert-map cert-to-security-name
           list entry is not compatible with the needed requirements
           of a NETCONF username, then it MUST be considered an invalid
           match and additional cert-map cert-to-security-name list entries MUST
           be searched looking for another potential match.

           If no matching and valid cert-map cert-to-security-name list entry can
           be found, then the NETCONF server MUST close the connection,
           and MUST NOT accept NETCONF messages over it.

           Security administrators are encouraged to make use of
           certificates with subjectAltName fields that can be used as
           NETCONF usernames so that a single root CA certificate can
           allow all child certificate's subjectAltName to map directly
           to a NETCONF usernames via a 1:1 transformation.";

         list cert-map cert-to-security-name {
           key "key";
      ordered-by user; id;
           description
        "A single
            "This list entry that specifies a mapping for an incoming
        TLS certificate defines how certificates are mapped to a NETCONF username.";
             security names.";
           reference "SNMP-TLS-TM-MIB.snmpTlstmCertToTSNEntry";

           leaf key id {
             type string;
        nacm:default-deny-all; uint32;
             description
              "The key associated with id specifies the cert-map list.";
      } order in which the entries in the
               cert-to-security-name container fingerprint {
        choice algorithm-and-hash {
          mandatory true;
          leaf md5 {
            type tls-fingerprint-type;
          }
          leaf sha1 {
            type tls-fingerprint-type;
          }
          leaf sha224 {
            type tls-fingerprint-type;
          }
          leaf sha256 {
            type tls-fingerprint-type;
          }
          leaf sha384 {
            type tls-fingerprint-type; are searched.  Entries
               with lower numbers are searched first.";
             reference "SNMP-TLS-TM-MIB.snmpTlstmCertToTSNID";
           }
           leaf sha512 fingerprint {
             type tls-fingerprint-type;
          } tls-fingerprint;
             mandatory true;
             description
              "Specifies a value with which the signature algorithm and cryptographic
             signature (fingerprint) used to identify an X.509
             certificate.

             Implementations of this YANG module MAY, but are not
             required to, implement all of these cryptographic signature
             algorithms.  Implementations fingerprint of this YANG module MUST
             implement at least one the
               certificate presented by the peer is compared.  If the
               fingerprint of these cryptographic signature
             algorithms.

             The available choices may be extended in the future as
             stronger cryptographic signature algorithms become
             available certificate presented by the peer does
               not match the fingerprint configured, then the entry is
               skipped and are deemed necessary."; the search for a match continues.";
             reference
            "RFC 5246: The Transport Layer Security (TLS) Protocol
             Version 1.2; Section 7.4.1.4.1,  Signature Algorithms";
        }  // choice algorithm-and-hash "SNMP-TLS-TM-MIB.snmpTlstmCertToTSNFingerprint";
           }    // container fingerprint

      choice map-type {
           leaf specified map-type {
             type nacm:user-name-type; identityref {
               base cert-to-tm-security-name;
             }
             mandatory true;
             description
            "Directly specifies
              "Specifies the NETCONF username to be algorithm used for this
             certificate.";
        }
        leaf-list from-certificate {
          ordered-by user;
          type enumeration {
            enum rfc822Name {
              description
                "Maps a subjectAltName's rfc822Name to a NETCONF username.
                 The local part of map the rfc822Name is passed unaltered but certificate
               presented by the domain-part of peer to the name MUST be passed in lowercase.
                 This mapping results in a 1:1 correspondence between
                 equivalent subjectAltName rfc822Name values and NETCONF
                 username values except username.

               Mappings that use the domain-part of the name
                 MUST be passed in lowercase.

                 Example rfc822Name Field:  FooBar@Example.COM
                 is mapped to NETCONF username: FooBar@example.com.";
            }
            enum dNSName {
              description
                "Maps a subjectAltName's dNSName to a NETCONF username after
                 first converting it to all lowercase (RFC 5280 does not
                 specify converting snmpTlstmCertToTSNData column
               need to lowercase so this involves an extra
                 step).  This mapping results in a 1:1 correspondence between
                 subjectAltName dNSName values and augment the NETCONF username
                 values.

                 reference:  RFC 5280 - Internet X.509 Public Key
                             Infrastructure Certificate and Certificate
                             Revocation List (CRL) Profile.";
            }
            enum ipAddress {
              description
                "Maps a subjectAltName's iPAddress 'cert-to-tm-security-name' list
               with additional configuration objects corresponding
               to a NETCONF username by
                 transforming the binary encoded address as follows:

                 1) for IPv4, the value is converted into a
                    decimal-dotted quad address (e.g., '192.0.2.1').

                 2) for IPv6 addresses, snmpTlstmCertToTSNData value.  Such objects
               should use the value is converted into a
                    32-character all lowercase hexadecimal string
                    without any colon separators.

                    This mapping results in a 1:1 correspondence between
                    subjectAltName iPAddress values and 'when' statement to make them
               conditional based on the NETCONF username
                    values.";
            }
          } 'map-type'.";
             reference "SNMP-TLS-TM-MIB.snmpTlstmCertToTSNMapType";
           }   // leaf-list from-certificate
           leaf cert-specified-security-name {
             when "../map-type = 'snmp:specified'";
             type nacm:user-name-type;
             mandatory true;
             description
          "Specifies
              "Directly specifies the algorithm for deriving a NETCONF username from
           a certificate.  If a mapping succeeds, then it will return a
           NETCONF username.

           If when the resulting mapped value
               'map-type' is not compatible with the
           needed requirements of a NETCONF username, then subsequent
           cert-map list entries MUST be searched for additional
           matches to look for a mapping that succeeds."; 'specified'.";
             reference "SNMP-TLS-TM-MIB.snmpTlstmCertToTSNData";
           }   // choice map-type
         }  // list cert-map cert-to-security-name
       }    // container cert-maps

      //
 //  Objects related to deriving NETCONF usernames from TLS pre-shared
      //  pre-shared keys.
 //

      container psk-maps {
        if-feature map-pre-shared-keys;
        description
         "During the TLS Handshake, the client indicates which key to
          use by including a PSK identity in the TLS ClientKeyExchange
          message. On the server side, this PSK identity is used to
          look up an entry in the psk-map list.  If such an entry is
          found, and the pre-shared keys match, then the client is
          authenticated. The server uses the value from the user-name
          leaf in the psk-map list as the NETCONF username.  If the
          server cannot find an entry in the psk-map list, or if the
          pre-shared keys do not match, then the server terminates
          the connection.  For details on how the PSK identity MAY be encoded
       in UTF-8, see section 5.1. of RFC 4279."; connection.";
        reference
         "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer
                    Security (TLS)";

        list psk-map {
          key psk-identity;

          leaf psk-identity {
            type string;
            description
             "The PSK identity encoded as a UTF-8 string."; string. For details on
              how the PSK identity MAY be encoded in UTF-8, see section
              5.1. of RFC 4279.";
            reference
             "RFC 4279: Pre-Shared Key Ciphersuites for Transport Layer
                        Security (TLS)";
          }
          leaf user-name {
            type nacm:user-name-type;
            mandatory true;
            description
             "The NETCONF username associated with this PSK identity.";
          }
          leaf valid-not-before {
            type yang:date-and-time;
            description
             "This PSK identity is not valid before the given data
              and time.";
          }
          leaf valid-not-after {
            type yang:date-and-time;
            description
             "This PSK identity is not valid before the given date
              and time.";
          }
          leaf key {
            type string {
              pattern '([0-9a-fA-F]){2}(:([0-9a-fA-F]){2})*';
            }
            mandatory true;
            nacm:default-deny-all;
            description
             "The key associated with the PSK identity";
      }
    }   // list psk-map
   }    // container psk-maps

  }     // container tls
 }      // container netconf-config
}

4. associated with the PSK identity";
          }
        }  // list psk-map
      }  // container psk-maps

     }  // container netconf-tls
   }

   <CODE ENDS>

5.  Usage Examples

5.1.  Certificate Mapping Configuration Example

   The following XML shows an example of parameters for mapping an X.509
   certificate to a NETCONF username:

     <netconf-tls
          xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-tls">
       <cert-maps>
         <cert-to-security-name>
           <id>10</id>
           <fingerprint>de:ad:be:ef</fingerprint>  <!-- Not valid -->
           <map-type>specified</map-type>
           <cert-specified-security-name>
              admin
           </cert-specified-security-name>
         </cert-to-security-name>
       </cert-maps>
     </netconf-tls>

5.2.  PSK Mapping Configuration Example

   The following XML shows an example of parameters for mapping a pre-
   shared key to a NETCONF username:

    <netconf-tls
        xmlns="urn:ietf:params:xml:ns:yang:ietf-netconf-tls">
      <psk-maps>
        <psk-map>
          <psk-identity>a8gc8]klh59</psk-identity>
          <user-name>admin</user-name>
          <valid-not-before>2013-01-01T00:00:00-00:00</valid-not-before>
          <valid-not-after>2014-01-01T00:00:00-00:00</valid-not-after>
        </psk-map>
      </psk-maps>
    </netconf-tls>

6.  Security Considerations

   The security considerations described throughout [RFC5246] and
   [RFC6241] apply here as well.

   This document in its current version 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, SSH transport can be used.

   An attacker might be able to inject arbitrary NETCONF messages via
   some application that does not carefully check exchanged messages.
   When the :base:1.1 capability is not advertised by both peers, an
   attacker might be able to deliberately insert the delimiter sequence
   ]]>]]> in a NETCONF message to create a DoS attack.  If the :base:1.1
   capability is not advertised by both peers, applications and NETCONF
   APIs MUST ensure that the delimiter sequence ]]>]]> never appears in
   NETCONF messages; otherwise, those messages can be dropped, garbled,
   or misinterpreted.  More specifically, if the delimiter sequence is
   found in a NETCONF message by the sender side, a robust
   implementation of this document SHOULD warn the user that illegal
   characters have been discovered.  If the delimiter sequence is found
   in a NETCONF message by the receiver side (including any XML
   attribute values, XML comments, or processing instructions), a robust
   implementation of this document MUST silently discard the message
   without further processing and then stop the NETCONF session.

   Finally, this document does not introduce any new security
   considerations compared to [RFC6242].

5.

7.  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 name "netconf-tls".  This port will be the default
   port for NETCONF over TLS, as defined in this document.

      Registration Contact:  Mohamad Badra, mbadra@gmail.com.
      Transport Protocol:  TCP.
      Port Number:  6513
      Broadcast, Multicast or Anycast: No.
      Port Name:  netconf-tls.
      Service Name: netconf.
      Reference: RFC 5539

6.

8.  Acknowledgements

   A significant amount of the text in Section 3 was lifted from
   [RFC4642].

   The author would like to acknowledge David Harrington, Miao Fuyou,
   Eric Rescorla, Simon Josefsson, Olivier Coupelon, Alfred Hoenes, and
   the NETCONF mailing list members for their comments on the document.
   The author also appreciates Bert Wijnen, Mehmet Ersue, and Dan
   Romascanu for their efforts on issues resolving discussion; and
   Charlie Kaufman, Pasi Eronen, and Tim Polk for the thorough review of
   previous versions of this document.

7.

   Juergen Schoenwaelder and was partly funded by Flamingo, a Network of
   Excellence project (ICT-318488) supported by the European Commission
   under its Seventh Framework Programme.

9.  Contributor's Address

   Ibrahim Hajjeh
   Ineovation
   France

   EMail: ibrahim.hajjeh@ineovation.fr

   Martin Bjorklund
   Tail-f Systems

   Email: mbj@tail-f.com

8.

10.  References

8.1.

10.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC4279]  Eronen, P. and H. Tschofenig, "Pre-Shared Key Ciphersuites
              for Transport Layer Security (TLS)", RFC 4279,
              December 2005.

   [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.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, June 2011.

   [RFC6353]  Hardaker, W., "Transport Layer Security (TLS) Transport
              Model for the Simple Network Management Protocol (SNMP)",
              RFC 6353, July 2011.

8.2.

10.2.  Informative References

   [RFC4642]  Murchison, K., Vinocur, J., and C. Newman, "Using
              Transport Layer Security (TLS) with Network News Transfer
              Protocol (NNTP)", RFC 4642, October 2006.

   [RFC5277]  Chisholm, S.

   [RFC4742]  Wasserman, M. and H. Trevino, "NETCONF Event
              Notifications", T. Goddard, "Using the NETCONF
              Configuration Protocol over Secure SHell (SSH)", RFC 5277, July 2008. 4742,
              December 2006.

   [RFC5539]  Badra, M., "NETCONF over Transport Layer Security (TLS)",
              RFC 5539, May 2009.

   [RFC6241]  Enns, R., Bjorklund, M., Schoenwaelder, J., and A.
              Bierman, "Network Configuration Protocol (NETCONF)",
              RFC 6241, June 2011.

Appendix A.  Change Log (to be removed by RFC Editor before publication)

A.1.  From draft-ietf-netconf-rfc5539bis-00  Open Issues

   o  The identities etc. have been essentially copied from the SNMP
      configuration model.  Are we really happy with this reuse by
      copying?  If so, do we keep the SNMP configuration model names or
      adapt them to
      draft-ietf-netconf-rfc5539bis-01 the NETCONF context?

   o  Update Section 3.2  Right now, the YANG module focuses on the username mapping only.
      There are certainly more configuration objects for the TLS
      transport, e.g., which ports to listen on, which CERT to use etc.

   o  Shall we add support for call home, i.e., a device, after
      initiating and address some issues raised during WGLC establishing a TCP connection and executing the TLS
      handshake, would switch role and subsequently act as a NETCONF
      server.  (This would likely also include new port numbers.)

A.2.  From draft-ietf-netconf-rfc5539bis-01 to
      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.

A.3.  From draft-badra-netconf-rfc5539bis-02 to
      draft-ietf-netconf-rfc5539bis-00

   o  Remove the reference to BEEP

   o  Rename  rename host-part to domain-part in the description of RFC822.

Authors' Addresses

   Mohamad Badra
   LIMOS Laboratory

   Email: mbadra@gmail.com

   Alan Luchuk
   SNMP Research Research, Inc.
   3001 Kimberlin Heights Road
   Knoxville, TN  37920
   US

   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/