RFC8241: Interface to the Routing System (I2RS) Security-Related Requirements

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Internet Engineering Task Force (IETF)                          S. Hares
Request for Comments: 8241                                        Huawei
Category: Informational                                       D. Migault
ISSN: 2070-1721                                               J. Halpern
                                                                Ericsson
                                                          September 2017


  Interface to the Routing System (I2RS) Security-Related Requirements

Abstract

   This document presents security-related requirements for the
   Interface to the Routing System (I2RS) protocol, which provides a new
   interface to the routing system described in the I2RS architecture
   document (RFC 7921).  The I2RS protocol is implemented by reusing
   portions of existing IETF protocols and adding new features to them.
   One such reuse is of the security features of a secure transport
   (e.g., Transport Layer Security (TLS), Secure SHell (SSH) Protocol,
   Datagram TLS (DTLS)) such as encryption, message integrity, mutual
   peer authentication, and anti-replay protection.  The new I2RS
   features to consider from a security perspective are as follows: a
   priority mechanism to handle multi-headed write transactions, an
   opaque secondary identifier that identifies an application using the
   I2RS client, and an extremely constrained read-only non-secure
   transport.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8241.









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Copyright Notice

   Copyright (c) 2017 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
   (https://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
   2. Terminology and Concepts ........................................4
      2.1. Requirements Language ......................................4
      2.2. Security Terminology .......................................4
      2.3. I2RS-Specific Terminology ..................................5
      2.4. Concepts ...................................................5
   3. Security Features and Protocols: Reused and New .................6
      3.1. Security Protocols Reused by the I2RS Protocol .............6
      3.2. New Features Related to Security ...........................7
      3.3. I2RS Protocol Security Requirements vs. IETF
           Management Protocols .......................................8
   4. Security-Related Requirements ..................................10
      4.1. I2RS Peer (Agent and Client) Identity Authentication ......10
      4.2. Identity Validation before Role-Based Message Actions .....11
      4.3. Peer Identity, Priority, and Client Redundancy ............12
      4.4. Multi-Channel Transport: Secure and Non-Secure ............13
      4.5. Management Protocol Security ..............................15
      4.6. Role-Based Data Model Security ............................16
      4.7. Security of the Environment ...............................17
   5. IANA Considerations ............................................17
   6. Security Considerations ........................................17
   7. References .....................................................18
      7.1. Normative References ......................................18
      7.2. Informative References ....................................18
   Acknowledgements ..................................................20
   Authors' Addresses ................................................20








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1.  Introduction

   The Interface to the Routing System (I2RS) protocol provides read and
   write access to information and state within the routing system.  An
   I2RS client interacts with one or more I2RS agents to collect
   information from network routing systems.  [RFC7921] describes the
   architecture of this interface, and this document assumes the reader
   is familiar with this architecture and its definitions.

   The I2RS interface is instantiated by the I2RS protocol connecting an
   I2RS client and an I2RS agent associated with a routing system.  The
   I2RS protocol is implemented by reusing portions of existing IETF
   protocols and adding new features to them.  As a reuse protocol, it
   can be considered a higher-layer protocol because it can be
   instantiated in multiple management protocols (e.g., NETCONF
   [RFC6241] or RESTCONF [RFC8040]) operating over a secure transport.
   These protocols are what provide its security.

   This document is part of a suite of documents outlining requirements
   for the I2RS protocol, which also includes the following:

   o  "An Architecture for the Interface to the Routing System"
      [RFC7921]

   o  "I2RS Ephemeral State Requirements" [RFC8242]

   o  "Interface to the Routing System (I2RS) Traceability: Framework
      and Information Model" (which discusses traceability) [RFC7923]

   o  "Requirements for Subscription to YANG Datastores" (which
      highlights the publication/subscription requirements) [RFC7922]

   Since the I2RS "higher-layer" protocol changes the interface to the
   routing systems, it is important that implementers understand the new
   security requirements for the environment the I2RS protocol operates
   in.  A summary of the I2RS protocol security environment is found in
   the I2RS architecture [RFC7921].

   I2RS reuses the secure transport protocols (TLS, SSH, DTLS) that
   support encryption, message integrity, peer authentication, and key
   distribution protocols.  Optionally, implementers may utilize
   Authentication, Authorization, and Accounting (AAA) protocols (Radius
   over TLS or Diameter over TLS) to securely distribute identity
   information.

   Section 2 highlights some of the terminology and concepts that the
   reader is required to be familiar with.




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   Section 3 provides an overview of security features and protocols
   being reused (Section 3.1), lists the new security features being
   required (Section 3.2), and explores how existing and new security
   features and protocols would be paired with existing IETF management
   protocols (Section 3.3).

   The new features I2RS extends to these protocols are a priority
   mechanism to handle multi-headed writes, an opaque secondary
   identifier to allow traceability of an application utilizing a
   specific I2RS client to communicate with an I2RS agent, and non-
   secure transport constrained to be used only for read-only data,
   which may include publicly available data (e.g., public BGP events,
   public telemetry information, web service availability) and some
   legacy data.

   Section 4 provides the I2RS protocol security requirements of several
   security features.  Protocols designed to be I2RS higher-layer
   protocols need to fulfill these security requirements.

2.  Terminology and Concepts

2.1.  Requirements Language

   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.

2.2.  Security Terminology

   This document uses the terminology found in [RFC4949] and [RFC7921].
   Specifically, this document reuses the following terms from
   [RFC4949]:

   o  access control
   o  authentication
   o  data confidentiality
   o  data integrity
   o  data privacy
   o  identity
   o  identifier
   o  mutual authentication
   o  role
   o  role-based access control
   o  security audit trail
   o  trust




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   [RFC7922] describes traceability for the I2RS interface and the I2RS
   protocol.  Traceability is not equivalent to a security audit trail
   or simple logging of information.  A security audit trail may utilize
   traceability information.

2.3.  I2RS-Specific Terminology

   This document discusses the security of the multiple I2RS
   communication channels that operate over the higher-layer I2RS
   protocol.  The higher-layer I2RS protocol combines a secure transport
   and I2RS contextual information, and it reuses IETF protocols and
   data models to create the secure transport and the contextual
   information driven by the I2RS data model.  To describe how the I2RS
   higher-layer protocol combines other protocols, the following terms
   are used:

   I2RS component protocols

      Protocols that are reused and combined to create the I2RS higher-
      layer protocol.

   I2RS secure transport component protocols (required)

      Secure transport protocols that combine to support the I2RS
      higher-layer protocol.

   I2RS management component protocols (required)

      Management protocols that combine to provide the management-
      information context for the I@RS higher-layer protocol.

   I2RS AAA component protocols (optional)

      AAA protocols supporting the I2RS higher-layer protocol.

2.4.  Concepts

   The reader should be familiar with the pervasive security
   requirements in [RFC7258].

   This document uses the following concepts from the I2RS architecture
   [RFC7921] listed below with their respective section numbers from
   said RFC:

   o  I2RS client, agent, and protocol (Section 2)

   o  I2RS higher-layer protocol (Section 7.2)




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   o  scope: read, notification, identity, and write (Section 2)

   o  identity and secondary identity (Section 2)

   o  roles or security rules (Section 2)

   o  routing system/subsystem (Section 2)

   o  I2RS assumed security environment (Section 4)

   o  I2RS identity and authentication (Section 4.1)

   o  scope of Authorization in I2RS client and agent (Section 4.2)

   o  client redundancy with a single client identity (Section 4.3),

   o  restrictions on I2RS in personal devices (Section 4.4)

   o  communication channels and I2RS higher-layer protocol
      (Section 7.2)

   o  active communication versus connectivity (Section 7.5)

   o  multi-headed control (Section 7.8)

   o  transaction, message, multi-message atomicity (Section 7.9)

3.  Security Features and Protocols: Reused and New

3.1.  Security Protocols Reused by the I2RS Protocol

   I2RS requires a secure transport protocol and key distribution
   protocols.  The secure transport for I2RS requires one to provide
   peer authentication.  In addition, the features required for I2RS
   messages are confidentiality, authentication, and replay protection.
   According to [RFC8095], the secure transport protocols that support
   peer authentication, confidentiality, data integrity, and replay
   protection are the following:

   1.  TLS [RFC5246] over TCP or Stream Control Transmission Protocol
       (SCTP)

   2.  DTLS over UDP with replay detection and an anti-DoS stateless
       cookie mechanism required for the I2RS protocol and the DTLS
       options of record-size negotiation and conveyance of the Don't
       Fragment (DF) bit are set for IPv4, or no fragmentation extension
       headers for IPv6 to be optional in deployments are allowed by the
       I2RS protocol



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   3.  HTTP over TLS (over TCP or SCTP)

   4.  HTTP over DTLS (with the requirements and optional features
       specified above in item 2)

   As detailed in Section 3.3, the following protocols would need to be
   extended to provide confidentiality, data integrity, peer
   authentication, and key distribution and to run over a secure
   transport (TLS or DTLS):

   o  IP Flow Information Export (IPFIX) over SCTP, TCP, or UDP

   o  Forwarding and Control Element Separation (ForCES) Transport
      Mapping Layer (TML) over SCTP

   The specific type of key management protocols an I2RS secure
   transport uses depends on the transport.  Key management protocols
   utilized for the I2RS protocols SHOULD support automatic rotation.

   An I2RS implementer may use AAA protocols over secure transport to
   distribute the identities for the I2RS client, I2RS agent, and role-
   authorization information.  Two AAA protocols are as follows:
   Diameter [RFC6733] and Radius [RFC2865].  To provide I2RS peer
   identities with the best security, the AAA protocols MUST be run over
   a secure transport (Diameter over secure transport (TLS over TCP)
   [RFC6733]), Radius over a secure transport (TLS) [RFC6614]).

3.2.  New Features Related to Security

   The new features are priority, an opaque secondary identifier, and a
   non-secure protocol for read-only data constrained to specific
   standard usages.  The I2RS protocol allows multi-headed control by
   several I2RS clients.  This multi-headed control is based on the
   assumption that the operator deploying the I2RS clients, I2RS agents,
   and the I2RS protocol will coordinate the read, write, and
   notification scope so the I2RS clients will not contend for the same
   write scope.  However, just in case there is an unforeseen overlap of
   I2RS clients attempting to write a particular piece of data, the I2RS
   architecture [RFC7921] provides the concept of each I2RS client
   having a priority.  The I2RS client with the highest priority will
   have its write succeed.  This document specifies requirements for
   this new concept of priority (see Section 4.3).

   The opaque secondary identifier identifies an application that uses
   communication from the I2RS client to I2RS agent to manage the
   routing system.  The secondary identifier is opaque to the I2RS
   protocol.  In order to protect personal privacy, the secondary
   identifier should not contain identifiable personal information.



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   The last new feature related to I2RS security is the ability to allow
   nonconfidential data to be transferred over a non-secure transport.
   It is expected that most I2RS data models will describe information
   that will be transferred with confidentiality.  Therefore, any model
   that transfers data over a non-secure transport is marked.  The use
   of a non-secure transport is optional, and an implementer SHOULD
   create knobs that allow data marked as nonconfidential to be sent
   over a secure transport.

   Nonconfidential data can only be data with read-scope or
   notification-scope transmission of events.  Nonconfidential data
   cannot have write-scope or notification-scope configuration.
   Examples of nonconfidential data would be the telemetry information
   that is publicly known (e.g., BGP route-views data or website status
   data) or some legacy data (e.g., interface) that cannot be
   transported using secure transport.  The IETF I2RS data models MUST
   indicate (in the model) the specific data that is nonconfidential.

   Most I2RS data models will expect that the information described in
   the model will be transferred with confidentiality.

3.3.  I2RS Protocol Security Requirements vs. IETF Management Protocols

   Figure 1 provides a partial list of the candidate management
   protocols.  It also lists the secure transports each protocol
   supports.  The column on the right of the table indicates whether or
   not the transport protocol will need I2RS security extensions.
























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     Management                         I2RS Security
     Protocol   Transport Protocol      Extensions
     =========  =====================   =================
     NETCONF     TLS over TCP (*1)      None required (*2)

     RESTCONF    HTTP over TLS with     None required (*2)
                 X.509v3 certificates,
                 certificate validation,
                 mutual authentication:
                 1) authenticated
                    server identity,
                 2) authenticated
                    client identity
                (*1)

      ForCES    TML over SCTP           Needs an extension to
                (*1)                    TML to run TML over
                                        TLS over SCTP, or
                                        DTLS with options for
                                        replay protection
                                        and anti-DoS stateless
                                        cookie mechanism.
                                        (DTLS record size
                                        negotiation and conveyance
                                        of DF bits are optional).
                                        The IPsec mechanism is
                                        not sufficient for
                                        I2RS traveling over
                                        multiple hops
                                        (router + link) (*2)

      IPFIX     SCTP, TCP, UDP          Needs an extension
                TLS or DTLS for         to support TLS or DTLS with
                secure client (*1)      options for replay protection
                                        and anti-DoS stateless
                                        cookie mechanism.
                                        (DTLS record size
                                        negotiation and conveyance
                                        of DF bits are optional)


       *1 - Key management protocols MUST support appropriate key
            rotation.

       *2 - Identity and role authorization distributed by Diameter or
            Radius MUST use Diameter over TLS or Radius over TLS.

   Figure 1: Candidate Management Protocols and Their Secure Transports



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4.  Security-Related Requirements

   This section discusses security requirements based on the following
   security functions:

   o  peer identity authentication (Section 4.1)

   o  Peer Identity validation before role-based message actions
      (Section 4.2)

   o  peer identity and client redundancy (Section 4.3)

   o  multi-channel transport requirements: Secure transport and non-
      secure Transport (Section 4.4)

   o  management protocol security requirements (Section 4.5)

   o  role-based security (Section 4.6)

   o  security environment (Section 4.7)

   The I2RS protocol depends upon a secure transport layer for peer
   authentication, data integrity, confidentiality, and replay
   protection.  The optional non-secure transport can only be used for a
   restricted set of data available publicly (events or information) or
   a select set of legacy data.  Data passed over the non-secure
   transport channel MUST NOT contain any data that identifies a person.

4.1.  I2RS Peer (Agent and Client) Identity Authentication

   Requirements:

      SEC-REQ-01: All I2RS clients and agents MUST have an identity and
      at least one unique identifier for each party in the I2RS protocol
      context.

      SEC-REQ-02: The I2RS protocol MUST utilize these identifiers for
      mutual identification of the I2RS client and agent.

      SEC-REQ-03: Identifier distribution and the loading of these
      identifiers into the I2RS agent and client SHOULD occur outside
      the I2RS protocol prior to the I2RS protocol establishing a
      connection between I2RS client and agent.  AAA protocols MAY be
      used to distribute these identifiers, but other mechanism can be
      used.






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   Explanation:

   These requirements are for I2RS peer (I2RS agent and client)
   authentication.  A secure transport (e.g., TLS) will authenticate
   based on these identities, but these identities are for the I2RS
   management layer.  A AAA protocol distributing I2RS identity
   information SHOULD transport its information over a secure transport.

4.2.  Identity Validation before Role-Based Message Actions

   Requirements:

      SEC-REQ-04: An I2RS agent receiving a request from an I2RS client
      MUST confirm that the I2RS client has a valid identity.

      SEC-REQ-05: An I2RS client receiving an I2RS message over a secure
      transport MUST confirm that the I2RS agent has a valid identifier.

      SEC-REQ-06: An I2RS agent receiving an I2RS message over a non-
      secure transport MUST confirm that the content is suitable for
      transfer over such a transport.

   Explanation:

   Each I2RS client has a scope based on its identity and the security
   roles (read, write, or events) associated with that identity, and
   that scope must be considered in processing an I2RS message sent on a
   communication channel.  An I2RS communication channel may utilize
   multiple transport sessions or establish a transport session and then
   close the transport session.  Therefore, it is important that the
   I2RS peers operate utilizing valid peer identities when a message is
   processed rather than checking if a transport session exists.

   During the time period when a secure transport session is active, the
   I2RS agent SHOULD assume that the I2RS client's identity remains
   valid.  Similarly, while a secure connection exists that included
   validating the I2RS agent's identity and a message is received via
   that connection, the I2RS client SHOULD assume that the I2RS agent's
   identity remains valid.

   The definition of what constitutes a valid identity or a valid
   identifier MUST be defined by the I2RS protocol.









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4.3.  Peer Identity, Priority, and Client Redundancy

   Requirements:

      SEC-REQ-07: Each I2RS identifier MUST be associated with just one
      priority.

      SEC-REQ-08: Each identifier is associated with one secondary
      identifier during a particular I2RS transaction (e.g., read/write
      sequence), but the secondary identifier may vary during the time a
      connection between the I2RS client and I2RS agent is active.

   Explanation:

   The I2RS architecture also allows multiple I2RS clients with unique
   identities to connect to an I2RS agent (see Section 7.8 of
   [RFC7921]).  The I2RS deployment using multiple clients SHOULD
   coordinate this multi-headed control of I2RS agents by I2RS clients
   so no conflict occurs in the write scope.  However, in the case of
   conflict on a write-scope variable, the error resolution mechanisms
   defined by the I2RS architecture multi-headed control (Section 7.8 of
   [RFC7921]) allow the I2RS agent to deterministically choose one I2RS
   client.  The I2RS client with highest priority is given permission to
   write the variable, and the second client receives an error message.

   A single I2RS client may be associated with multiple applications
   with different tasks (e.g., weekly configurations or emergency
   configurations).  The secondary identity is an opaque value that the
   I2RS client passes to the I2RS agent so that this opaque value can be
   placed in the tracing file or event stream to identify the
   application using the communication from I2RS client to agent.  The
   I2RS client is trusted to simply assert the secondary identifier.

   One example of the use of the secondary identity is the situation
   where an operator of a network has two applications that use an I2RS
   client.  The first application is a weekly configuration application
   that uses the I2RS protocol to change configurations.  The second
   application allows operators to makes emergency changes to routers in
   the network.  Both of these applications use the same I2RS client to
   write to an I2RS agent.  In order for traceability to determine which
   application (weekly configuration or emergency) wrote some
   configuration changes to a router, the I2RS client sends a different
   opaque value for each of the applications.  The weekly configuration
   secondary opaque value could be "xzzy-splot" and the emergency
   secondary opaque value could be "splish-splash".






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   A second example is if the I2RS client is used for the monitoring of
   critical infrastructure.  The operator of a network using the I2RS
   client may desire I2RS client redundancy where the monitoring
   application with the I2RS client is deployed on two different boxes
   with the same I2RS client identity (see Section 4.3 of [RFC7921]).
   These two monitoring applications pass to the I2RS client whether the
   application is the primary or back-up application, and the I2RS
   client passes this information in the I2RS secondary identifier, as
   the figure below shows.  The primary application's secondary
   identifier is "primary-monitoring", and the back-up application
   secondary identifier is "backup-monitoring".  The I2RS tracing
   information will include the secondary identifier information along
   with the transport information in the tracing file in the agent.

   Application A--I2RS client--Secure transport(#1)
    [I2RS identity 1, secondary identifier: "primary-monitoring"]-->

   Application B--I2RS client--Secure transport(#2)
    [I2RS identity 1, secondary identifier: "backup-monitoring"]-->

         Figure 2: Primary and Back-Up Application for Monitoring
                       Identification Sent to Agent

4.4.  Multi-Channel Transport: Secure and Non-Secure

   Requirements:

      SEC-REQ-09: The I2RS protocol MUST be able to transfer data over a
      secure transport and optionally MAY be able to transfer data over
      a non-secure transport.  The default transport is a secure
      transport, and this secure transport is mandatory to implement in
      all I2RS agents and in any I2RS client that a) performs a write
      scope transaction that is sent to the I2RS agent or b) configures
      an Event Scope transaction.  This secure transport is mandatory to
      use on any I2RS client's Write transaction or the configuration of
      an Event Scope transaction.

      SEC-REQ-10: The secure transport MUST provide data
      confidentiality, data integrity, and practical replay prevention.

      SEC-REQ-11: The I2RS client and I2RS agent SHOULD implement
      mechanisms that mitigate DoS attacks.  This means the secure
      transport must support DoS prevention.  For the non-secure
      transport, the I2RS higher-layer protocol MUST contain a transport
      management layer that considers the detection of DoS attacks and
      provides a warning over a secure transport channel.





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      SEC-REQ-12: A secure transport MUST be associated with a key
      management solution that can guarantee that only the entities
      having sufficient privileges can get the keys to encrypt/decrypt
      the sensitive data.

      SEC-REQ-13: A machine-readable mechanism to indicate that a data
      model contains nonconfidential data MUST be provided.  A non-
      secure transport MAY be used to publish only read-scope or
      notification-scope data if the associated data model indicates
      that the data in question is nonconfidential.

      SEC-REQ-14: The I2RS protocol MUST be able to support multiple
      secure transport sessions providing protocol and data
      communication between an I2RS agent and client.  However, a single
      connection between I2RS agent and client MAY elect to use a single
      secure transport session or a single non-secure transport session
      conforming to the requirements above.

      SEC-REQ-15: Deployment configuration knobs SHOULD be created to
      allow operators to send "nonconfidential" read scope (data or
      event streams) over a secure transport.

      SEC-REQ-16: The I2RS protocol makes use of both secure and non-
      secure transports, but this use MUST NOT be done in any way that
      weakens the secure transport protocol used in the I2RS protocol or
      other contexts that do not have this requirement for mixing secure
      and non-secure modes of operation.

   Explanation:

   The I2RS architecture defines three scopes: read, write, and
   notification.  Non-secure data can only be used for read and
   notification scopes of "nonconfidential data".  The configuration of
   ephemeral data in the I2RS agent uses write scope either for data or
   for configuration of event notification streams.  The requirement to
   use secure transport for configuration prevents accidental or
   malevolent entities from altering the I2RS routing system through the
   I2RS agent.

   It is anticipated that the passing of most I2RS ephemeral state
   operational statuses SHOULD be done over a secure transport.

   In most circumstances, the secure transport protocol will be
   associated with a key management system.  Most deployments of the
   I2RS protocol will allow for automatic key management systems.  Since
   the data models for the I2RS protocol will control key routing
   functions, it is important that deployments of I2RS use automatic key
   management systems.



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   Per BCP 107 [RFC4107], while key management systems SHOULD be
   automatic, the systems MAY be manual in the following scenarios:

   a)  The environment has limited bandwidth or high round-trip times.

   b)  The information being protected has low value.

   c)  The total volume of traffic over the entire lifetime of the long-
       term session key will be very low.

   d)  The scale of the deployment is limited.

   Operators deploying the I2RS protocol selecting manual key management
   SHOULD consider both short- and medium-term plans.  Deploying
   automatic systems initially may save effort in the long term.

4.5.  Management Protocol Security

   Requirements:

      SEC-REQ-17: In a critical infrastructure, certain data within
      routing elements is sensitive and read/write operations on such
      data SHOULD be controlled in order to protect its confidentiality.
      To achieve this, higher-layer protocols MUST utilize a secure
      transport, and they SHOULD provide access-control functions to
      protect confidentiality of the data.

      SEC-REQ-18: An integrity protection mechanism for I2RS MUST be
      provided that will be able to ensure the following:

      1)  the data being protected is not modified without detection
          during its transportation,

      2)  the data is actually from where it is expected to come from,
          and

      3)  the data is not repeated from some earlier interaction the
          higher-layer protocol (best effort).

      The I2RS higher-layer protocol operating over a secure transport
      provides this integrity.  The I2RS higher-layer protocol operating
      over a non-secure transport SHOULD provide some way for the client
      receiving nonconfidential read-scoped or event-scoped data over
      the non-secure connection to detect when the data integrity is
      questionable; and in the event of a questionable data integrity,
      the I2RS client should disconnect the non-secure transport
      connection.




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      SEC-REQ-19: The I2RS higher-layer protocol MUST provide a
      mechanism for message traceability (requirements in [RFC7922])
      that supports the tracking higher-layer functions run across
      secure connection or a non-secure transport.

   Explanation:

   Most carriers do not want a router's configuration and data-flow
   statistics to be known by hackers or their competitors.  While
   carriers may share peering information, most carriers do not share
   configuration and traffic statistics.  To achieve this, the I2RS
   higher-layer protocol (e.g., NETCONF) requires access control
   (NETCONF Access Control Model [RFC6536]) for sensitive data needs to
   be provided; and the confidentiality protection on such data during
   transportation needs to be enforced.

   Integrity of data is important even if the I2RS protocol is sending
   nonconfidential data over a non-secure connection.  The ability to
   trace I2RS protocol messages that enact I2RS transactions provides a
   minimal aid to helping operators check how messages enact
   transactions on a secure or non-secure transport.  Contextual checks
   on specific nonconfidential data sent over a non-secure connection
   may indicate the data has been modified.

4.6.  Role-Based Data Model Security

   In order to make access control more manageable, the I2RS
   architecture [RFC7921] specifies a "role" to categorize users into a
   group (rather than handling them individually) for access-control
   purposes (role-based access control).  Therefore, an I2RS role
   specifies the access control for a group as being read, write, or
   notification.

      SEC-REQ-20: The rules around what I2RS security role is permitted
      to access and manipulate what information over a secure transport
      (which protects the data in transit) SHOULD ensure that data of
      any level of sensitivity is reasonably protected from being
      observed by those without permission to view it, so that privacy
      requirements are met.

      SEC-REQ-21: Role security MUST work when multiple transport
      connections are being used between the I2RS client and agent as
      the I2RS architecture [RFC7921] describes.

      Sec-REQ-22: If an I2RS agent or client is tightly correlated with
      a person, then the I2RS protocol and data models SHOULD provide
      additional security that protects the person's privacy.




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   Explanation:

   An I2RS higher-layer protocol uses a management protocol (e.g.,
   NETCONF, RESTCONF) to pass messages in order to enact I2RS
   transactions.  Role security must secure data (sensitive and normal
   data) in a router even when it is operating over multiple connections
   at the same time.  NETCONF can run over TLS (over TCP or SCTP) or
   SSH.  RESTCONF runs over HTTP over a secure transport (TLS).  SCTP
   [RFC4960] provides security for multiple streams plus end-to-end
   transport of data.  Some I2RS functions may wish to operate over DTLS
   [RFC6347], which runs over UDP ([RFC768]) and SCTP ([RFC5764]).

   Please note the security of the connection between application and
   I2RS client is outside of the I2RS protocol or I2RS interface.

   While I2RS clients are expected to be related to network devices and
   not individual people, if an I2RS client ran on a person's phone,
   then privacy protection to anonymize any data relating to a person's
   identity or location would be needed.

   A variety of forms of management may set policy on roles: "operator-
   applied knobs", roles that restrict personal access, data models with
   specific "privacy roles", and access filters.

4.7.  Security of the Environment

   The security for the implementation of a protocol also considers the
   protocol environment.  Implementers should review the summary of the
   I2RS security environment in [RFC7921].

5.  IANA Considerations

   This document does not require any IANA actions.

6.  Security Considerations

   This is a document about security requirements for the I2RS protocol
   and data models.  Security considerations for the I2RS protocol
   include both the protocol and the security environment.












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7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4107]  Bellovin, S. and R. Housley, "Guidelines for Cryptographic
              Key Management", BCP 107, RFC 4107, DOI 10.17487/RFC4107,
              June 2005, <https://www.rfc-editor.org/info/rfc4107>.

   [RFC4949]  Shirey, R., "Internet Security Glossary, Version 2",
              FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
              <https://www.rfc-editor.org/info/rfc4949>.

   [RFC7258]  Farrell, S. and H. Tschofenig, "Pervasive Monitoring Is an
              Attack", BCP 188, RFC 7258, DOI 10.17487/RFC7258, May
              2014, <https://www.rfc-editor.org/info/rfc7258>.

   [RFC7921]  Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
              Nadeau, "An Architecture for the Interface to the Routing
              System", RFC 7921, DOI 10.17487/RFC7921, June 2016,
              <https://www.rfc-editor.org/info/rfc7921>.

   [RFC7922]  Clarke, J., Salgueiro, G., and C. Pignataro, "Interface to
              the Routing System (I2RS) Traceability: Framework and
              Information Model", RFC 7922, DOI 10.17487/RFC7922, June
              2016, <https://www.rfc-editor.org/info/rfc7922>.

   [RFC7923]  Voit, E., Clemm, A., and A. Gonzalez Prieto, "Requirements
              for Subscription to YANG Datastores", RFC 7923,
              DOI 10.17487/RFC7923, June 2016,
              <https://www.rfc-editor.org/info/rfc7923>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

7.2.  Informative References

   [RFC768]   Postel, J., "User Datagram Protocol", STD 6, RFC 768,
              DOI 10.17487/RFC0768, August 1980,
              <https://www.rfc-editor.org/info/rfc768>.






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   [RFC2865]  Rigney, C., Willens, S., Rubens, A., and W. Simpson,
              "Remote Authentication Dial In User Service (RADIUS)",
              RFC 2865, DOI 10.17487/RFC2865, June 2000,
              <https://www.rfc-editor.org/info/rfc2865>.

   [RFC4960]  Stewart, R., Ed., "Stream Control Transmission Protocol",
              RFC 4960, DOI 10.17487/RFC4960, September 2007,
              <https://www.rfc-editor.org/info/rfc4960>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [RFC5764]  McGrew, D. and E. Rescorla, "Datagram Transport Layer
              Security (DTLS) Extension to Establish Keys for the Secure
              Real-time Transport Protocol (SRTP)", RFC 5764,
              DOI 10.17487/RFC5764, May 2010,
              <https://www.rfc-editor.org/info/rfc5764>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [RFC6347]  Rescorla, E. and N. Modadugu, "Datagram Transport Layer
              Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
              January 2012, <https://www.rfc-editor.org/info/rfc6347>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012,
              <https://www.rfc-editor.org/info/rfc6536>.

   [RFC6614]  Winter, S., McCauley, M., Venaas, S., and K. Wierenga,
              "Transport Layer Security (TLS) Encryption for RADIUS",
              RFC 6614, DOI 10.17487/RFC6614, May 2012,
              <https://www.rfc-editor.org/info/rfc6614>.

   [RFC6733]  Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
              Ed., "Diameter Base Protocol", RFC 6733,
              DOI 10.17487/RFC6733, October 2012,
              <https://www.rfc-editor.org/info/rfc6733>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/info/rfc8040>.




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   [RFC8095]  Fairhurst, G., Ed., Trammell, B., Ed., and M. Kuehlewind,
              Ed., "Services Provided by IETF Transport Protocols and
              Congestion Control Mechanisms", RFC 8095,
              DOI 10.17487/RFC8095, March 2017,
              <https://www.rfc-editor.org/info/rfc8095>.

   [RFC8242]  Haas, J. and S. Hares, "Interface to the Routing System
              (I2RS) Ephemeral State Requirements", RFC 8242,
              DOI 10.17487/RFC8242, September 2017,
              <http://www.rfc-editor.org/info/rfc8242>.

Acknowledgements

   The authors would like to thank Wes George, Ahmed Abro, Qin Wu, Eric
   Yu, Joel Halpern, Scott Brim, Nancy Cam-Winget, Dacheng Zhang, Alia
   Atlas, and Jeff Haas for their contributions to the I2RS security
   requirements discussion and this document.  The authors would like to
   thank Bob Moskowitz, Kathleen Moriarty, Stephen Farrell, Radia
   Perlman, Alvaro Retana, Ben Campbell, and Alissa Cooper for their
   review of these requirements.

Authors' Addresses

   Susan Hares
   Huawei
   7453 Hickory Hill
   Saline, MI  48176
   United States of America

   Email: shares@ndzh.com


   Daniel Migault
   Ericsson
   8275 Trans Canada Route
   Saint Laurent, QC  H4S
   Canada

   Email: daniel.migault@ericsson.com


   Joel Halpern
   Ericsson
   United States of America

   Email: joel.halpern@ericsson.com





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