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Versions: (RFC 5539) 00 01 02 draft-ietf-netconf-rfc5539bis

NETCONF Working Group                                           M. Badra
Internet-Draft                                         Dhofar University
Obsoletes: 5539 (if approved)                             April 28, 2012
Intended status: Standards Track
Expires: October 30, 2012


              NETCONF Over Transport Layer Security (TLS)
                   draft-badra-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 October 30, 2012.

Copyright Notice

   Copyright (c) 2012 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



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   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
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . . 16
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 16
   6.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 17
   7.  Contributor's Address  . . . . . . . . . . . . . . . . . . . . 17
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 18
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 18
     8.2.  Informative References . . . . . . . . . . . . . . . . . . 18
   Appendix A.  Change Log (to be removed by RFC Editor before
                publication)  . . . . . . . . . . . . . . . . . . . . 19
     A.1.  From -01 to -02  . . . . . . . . . . . . . . . . . . . . . 19
     A.2.  From -00 to -01  . . . . . . . . . . . . . . . . . . . . . 19
     A.3.  From RFC5539 to draft-badra-netconf-rfc5539bis-00  . . . . 19
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 19























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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 client actively opens the TLS connection and the server
   passively listens for the incoming TLS connection on the TCP port
   6513.  It 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, and the server will respond with complete XML
   documents containing <rpc-reply> elements.  The client MAY indicate
   interest in receiving event notifications from a server by creating a
   subscription to receive event notifications [RFC5277].  In this case,
   the server replies to indicate whether the subscription request was
   successful and, if it was successful, the server begins sending the
   event notifications to the client as the events occur within the
   system.

   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



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   records.

   The previous version [RFC5539] of this document used the same framing
   sequence defined in [RFC6242], 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 of the protocol specified in this document MAY
   implement any TLS cipher suite that provides mutual authentication
   [RFC5246].

   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
   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.  The NETCONF server
   MUST NOT process any NETCONF messages received after the <close-
   session> operation.  The TLS session is closed as described in
   [RFC6242] Section 7.2.1.


3.  Endpoint Authentication, Identification and Authorization

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



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   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 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 any configuration or
   state data is sent to or received from the client.

   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



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   certificates specified in 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.  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 MAY
   use any of the following algorithms to produce the 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 certificate-to-
   username-transforms container in the ietf-netconf-tls YANG module
   specifies how a NETCONF server transforms a certificate into a
   NETCONF username.





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3.2.1.1.  Identifying a Certificate

   A client certificate has an identity: the certificate.  The TLS and
   corresponding protocols provide an identity.  The identity shows that
   "this client certificate has shown that it, indeed, is on the other
   side of the connection".  With a complete certificate, the
   certificate receiver can be certain that for someone or something on
   the other side to use that certificate successfully, it has the
   associated private key.

   The problem with using the entire certificates as the identity is
   that they are difficult for people to use.  It is generally accepted
   that a fingerprint of a certificate is not likely to come up with a
   collision against a fingerprint of another (different) certificate.
   Thus, assuming a good hash algorithm, a fingerprint can be a safe
   short-hand for identifying a certificate.

   If a locally held copy of a trusted CA certificate is configured in
   the transformation container, and that CA certificate was used to
   validate the path to the presented certificate, then the NETCONF
   server SHOULD use that list entry in the transformation container.
   All presented certificates validated by the configured CA certificate
   will be transformed to NETCONF usernames using the same
   transformation algorithm.

3.2.1.2.  Deriving NETCONF Usernames From PSK identities

   Implementations MAY optionally support TLS Pre-Shared Key (PSK)
   authentication [RFC4279].  RFC4279 describes pre-shared key
   ciphersuites for TLS.  During the TLS Handshake, the client indicates
   which key to use by including a "PSK identity" in the TLS
   ClientKeyExchange message [RFC4279].  On the server side, this PSK
   identity is used to look up the key corresponding to the presented
   PSK identity.  If the selected pre-shared keys match and the key is
   valid, then the client is authenticated and the NETCONF username
   associated with the PSK identity.  For details on how the PSK
   identity MAY be encoded in UTF-8, see section 5.1. of RFC [RFC6241].

3.2.1.3.  Remote Configuration

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



 module ietf-netconf-tls {




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  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>";

  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.

    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 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).




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    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 "2012-04-11" {
   description
     "Incorporates comments on draft-badra-netconf-rfc5539bis-01.txt.";
   reference
     "RFC XXXX: NETCONF over Transport Layer Security (TLS)";
  }

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


  feature map-certificates {
   description
     "The :map-certificates capability implements mapping X.509
      certificates to NETCONF user names.";
  }


  feature map-pre-shared-keys {
   description
     "The :map-pre-shared-keys capability implements mapping TLS
      pre-shared keys to NETCONF user names.";
  }


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


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



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  //  certificates.
  //

  container cert-mappings {
   if-feature map-certificates;
   config true;
   description
     "This 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 this container.  This
      container 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 this container), this container is consulted to determine the
      appropriate NETCONF username to associate with the remote
      connection.  This is done by considering each list entry from
      this container in prioritized order according to its index value.
      Each list entry's fingerprint value determines whether the list
      entry is a match for the incoming connection:

          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.

             This feature lets the NETCONF server derive NETCONF
             usernames from all certificates signed by the trusted
             CA certificate.  The NETCONF server will derive all
             NETCONF usernames using the same derivation algorithm.
             The NETCONF server requires only a single list entry
             to configure this behavior.

      Once a matching list entry has been found, the NETCONF server
      uses the map-type value to determine how the NETCONF username
      associated with the session should be determined.  See the map-
      type leaf's description for details on determining the NETCONF



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      username value.  If it is impossible to determine a NETCONF
      username from the list entry's data combined with the data
      presented in the certificate, then additional list entries MUST
      be searched looking for another potential match.  If a resulting
      NETCONF username mapped from a given list entry is not compatible
      with the needed requirements of a NETCONF username, then it MUST
      be considered an invalid match and additional list entries MUST
      be searched looking for another potential match.

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

      Non-consecutive values of index are acceptable and implementations
      should continue to the next highest numbered list entry.  It is
      recommended that administrators skip index values to leave room
      for the insertion of future list entries (for example, use values
      of 10 and 20 when creating initial list entries).

      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.  However, this container is
      flexible to allow for situations where existing deployed
      certificate infrastructures do not provide adequate subjectAltName
      values for use as NETCONF usernames.";


   list cert-map {
     key "index";
     description
       "A single list entry that specifies a mapping for an incoming
       TLS certificate to a NETCONF username.";

     leaf index {
       type uint32 {
         range "1..4294967295";
       }
       description
         "A unique, prioritized index for the given entry.  Lower
         numbers indicate a higher priority.";
     }

     container fingerprint {
       choice algorithm-and-hash {
         leaf md5 {
           type tls-fingerprint-type;



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         }
         leaf sha1 {
           type tls-fingerprint-type;
         }
         leaf sha224 {
           type tls-fingerprint-type;
         }
         leaf sha256 {
           type tls-fingerprint-type;
         }
         leaf sha384 {
           type tls-fingerprint-type;
         }
         leaf sha512 {
           type tls-fingerprint-type;
         }
         description
           "Specifies 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 of this YANG module MUST
            implement at least one of these cryptographic signature
            algorithms.

            The available choices may be extended in the future as
            stronger cryptographic signature algorithms become
            available and are deemed necessary.";

         reference
           "RFC 5246: The Transport Layer Security (TLS) Protocol
            Version 1.2; Section 7.4.1.4.1,  Signature Algorithms";
       }  // choice algorithm-and-hash
     }    // container fingerprint


     leaf map-type {
       type enumeration {
         enum specified                     { value 1;  }
         enum rfc822Name                    { value 2;  }
         enum dnsName                       { value 3;  }
         enum ipAddress                     { value 4;  }
         enum rfc822Name-dnsName-ipAddress  { value 5;  }
       }

       description



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         "Specifies the algorithm for deriving a NETCONF username from
         a certificate.  If a mapping succeeds, then it will return a
         NETCONF username.

         If the resulting mapped value is not compatible with the
         needed requirements of a NETCONF username, then subsequent
         list entries MUST be searched for additional NETCONF username
         matches to look for a mapping that succeeds.

         For each enumerated value listed above, the NETCONF server
         derives the NETCONF from the presented client certificate
         as described:

         specified

           Directly specifies the NETCONF username to be used for
           this certificate.  The value of the NETCONF username
           to use is specified in the data leaf of the list.  The
           data leaf MUST contain a non-zero length value or the
           mapping described in this list entry MUST be considered a
           failure.

         rfc822Name

           Maps a subjectAltName's rfc822Name to a NETCONF username.
           The local part of the rfc822Name is passed unaltered but
           the host-part of 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 that the host-part of the name
           MUST be passed in lowercase.

           Example rfc822Name Field:  FooBar@Example.COM
           is mapped to NETCONF username: FooBar@example.com.

         dnsName

           Maps a subjectAltName's dNSName to a NETCONF username after
           first converting it to all lowercase (RFC 5280 does not
           specify converting to lowercase so this involves an extra
           step).  This mapping results in a 1:1 correspondence between
           subjectAltName dNSName values and the NETCONF username
           values.

           reference:  RFC 5280 - Internet X.509 Public Key
                       Infrastructure Certificate and Certificate
                       Revocation List (CRL) Profile.




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         ipAddress

           Maps a subjectAltName's iPAddress 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, 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 the NETCONF username
              values.

         rfc822Name-dnsName-ipAddress

           The NETCONF server derives the NETCONF username from the
           subjectAltName fields rfc822Name, dnsName, and ipAddress,
           as described in sections above.  This enumeration specifies
           the NETCONF server first examines the rfc822Name, then
           examines the dnsName, then finally examines the ipAddress.
           The first matching subjectAltName value found in the
           certificate MUST be used when deriving the NETCONF username.

           These mappings result in a 1:1 correspondence between
           subjectAltName values and NETCONF username values.  The
           sub-mapping algorithms produced by these combined algorithms
           cannot produce conflicting results between themselves.";
     }  //  leaf map-type

     leaf data {
       type string {
         length "1..max";
       }
       description
         "Auxiliary data used as optional configuration information for
         a given mapping specified by the map-type leaf.  Only some
         mapping systems will make use of this leaf.  When the NETCONF
         server derives the NETCONF username from the client's presented
         certificate, the value in this leaf MUST be ignored for any
         mapping type that does not require data present in this leaf.";
     }
   }  // list cert-map
  }    // container cert-mappings





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

  container psk-map {
   if-feature map-pre-shared-keys;
   list psk {
     key psk-identity;

     leaf psk-identity {
       type string;
       description
         "The PSK identity encoded as a UTF-8 string.";
       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 data
          and time.";
     }

     leaf key {
       type string;
       pattern '([0-9a-fA-F]){2}(:([0-9a-fA-F]){2})*';
       nacm:default-deny-all;
       description
         "The key associated with the PSK identity";
     }
   }



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  }    // container psk-map
 }




4.  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, BEEP or 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.  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.






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      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.  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, Juergen Schoenwaelder, 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.  Contributor's Address

   Ibrahim Hajjeh
   Ineovation
   France

   EMail: ibrahim.hajjeh@ineovation.fr

   Alan Luchuk
   SNMP Research, Inc.
   3001 Kimberlin Heights Road
   Knoxville, TN  37920-9716

   EMail: luchuk@snmp.com

   Juergen Schoenwaelder
   Jacobs University Bremen
   Campus Ring 1
   28725 Bremen
   Germany

   EMail: j.schoenwaelder@jacobs-university.de





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8.  References

8.1.  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.  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. and H. Trevino, "NETCONF Event
              Notifications", RFC 5277, July 2008.

   [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.




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

A.1.  From -01 to -02

   o  Update the server identity check and add rfc6125

   o  Update the closure session and remove text related to close_notify
      alert specified by TLS

   o  Update YANG Module

A.2.  From -00 to -01

   o  Move RFC5539 to informative references and remove RFC4742.

   o  Shorten the YANG object names;

   o  Extend the YANG module to support configuration of PSK;

A.3.  From RFC5539 to draft-badra-netconf-rfc5539bis-00

   o  Added text on how the generation of a NETCONF username is done.

   o  Added text on how does this document fulfill the requirements in
      6241 for the format of the username.

   o  Removed unneeded wording about client/server, and changed use of
      client/server, manager/agent to TLS client/server and NETCONF
      client/server.

   o  Added text to Security Considerations about EOM issues.

   o  Added option for the chunked encoding described in RFC6242.

   o  Added 1.1 capability to enable the chunked encoding described in
      RFC6242.


Author's Address

   Mohamad Badra
   Dhofar University

   Email: mbadra@gmail.com







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