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Optimizing BFD Authentication
draft-ietf-bfd-optimizing-authentication-16

Document Type Active Internet-Draft (bfd WG)
Authors Mahesh Jethanandani , Ashesh Mishra , Ankur Saxena , Manav Bhatia , Jeffrey Haas
Last updated 2024-06-05 (Latest revision 2024-05-05)
Replaces draft-mahesh-bfd-authentication
RFC stream Internet Engineering Task Force (IETF)
Intended RFC status Proposed Standard
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Document shepherd Reshad Rahman
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Send notices to Reshad Rahman <rrahman@cisco.com>
draft-ietf-bfd-optimizing-authentication-16
Network Working Group                                    M. Jethanandani
Internet-Draft                                            Kloud Services
Updates: 5880 (if approved)                                    A. Mishra
Intended status: Standards Track                    Aalyria Technologies
Expires: 6 November 2024                                       A. Saxena
                                                       Ciena Corporation
                                                               M. Bhatia
                                                                  Google
                                                                 J. Haas
                                                        Juniper Networks
                                                              5 May 2024

                     Optimizing BFD Authentication
              draft-ietf-bfd-optimizing-authentication-16

Abstract

   This document describes an optimization to BFD Authentication as
   described in Section 6.7 of BFD RFC 5880.  This document updates RFC
   5880.

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 https://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 6 November 2024.

Copyright Notice

   Copyright (c) 2024 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

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   and restrictions with respect to this document.  Code Components
   extracted from this document must include Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   4
     1.2.  Note to RFC Editor  . . . . . . . . . . . . . . . . . . .   4
     1.3.  Terminology . . . . . . . . . . . . . . . . . . . . . . .   4
   2.  Authentication Mode . . . . . . . . . . . . . . . . . . . . .   5
   3.  Signaling Optimized Authentication  . . . . . . . . . . . . .   6
     3.1.  Error Handling  . . . . . . . . . . . . . . . . . . . . .   7
   4.  Optimized Authentication Operations . . . . . . . . . . . . .   7
   5.  Optimizing Authentication YANG Model  . . . . . . . . . . . .   8
     5.1.  Data Model Overview . . . . . . . . . . . . . . . . . . .   8
     5.2.  Tree Diagram  . . . . . . . . . . . . . . . . . . . . . .   8
     5.3.  The YANG Model  . . . . . . . . . . . . . . . . . . . . .   9
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  14
     6.1.  Auth Type . . . . . . . . . . . . . . . . . . . . . . . .  14
     6.2.  IETF XML Registry . . . . . . . . . . . . . . . . . . . .  15
     6.3.  The YANG Module Names Registry  . . . . . . . . . . . . .  15
     6.4.  Updated IANA Module . . . . . . . . . . . . . . . . . . .  15
   7.  Security Considerations . . . . . . . . . . . . . . . . . . .  15
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  16
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  16
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  16
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  18
   Appendix A.  Updated BFD IANA Module  . . . . . . . . . . . . . .  19
   Appendix B.  Examples . . . . . . . . . . . . . . . . . . . . . .  23
     B.1.  Single Hop BFD Configuration  . . . . . . . . . . . . . .  23
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  25

1.  Introduction

   Authenticating every BFD [RFC5880] control packet with MD5
   Message-Digest Algorithm [RFC1321], or Secure Hash Algorithm (SHA-1)
   is a computationally intensive process.  This makes it difficult, if
   not impossible to authenticate every packet - particularly at faster
   rates.  Also, the recent escalating series of attacks on MD5 and
   SHA-1 described in Finding Collisions in the Full SHA-1
   [SHA-1-attack1] and New Collision Search for SHA-1 [SHA-1-attack2]
   raise concerns about their remaining useful lifetime as outlined in
   Updated Security Considerations for the MD5 Message-Digest and the
   HMAC-MD5 Algorithm [RFC6151] and Security Considerations for the
   SHA-0 and SHA-1 Message-Digest Algorithm [RFC6194].  If replaced by
   stronger algorithms, the computational overhead, will make the task

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   of authenticating every packet even more difficult to achieve.

   This document proposes that BFD control packets that signal a state
   change, a demand mode change (to D bit), a poll sequence change (P or
   F bit change) be categorized as a significant change.  Control
   packets that do not require a poll sequence, such as
   bfd.RequiredMinRxInterval or bfd.RequiredMinTxInterval, are also
   considered as a significant change.  In other words, the contents of
   an Up packet MUST NOT change aside from the authentication section
   without stronger authentication to take advantage of the method
   described in this document.

   In the Up state, most packets that are transmitted and received have
   no state change associated with them.  Limiting authentication to
   packets that affect a BFD session's state allows more sessions to be
   supported with this optimized method of authentication.

   Once the session has reached the Up state, the session can choose a
   less computationally intensive Auth Type.  Currently, this includes:

   *  Meticulous Keyed ISAAC authentication as described in
      [I-D.ietf-bfd-secure-sequence-numbers].  This authentication type
      prevents the attack when the Up packets do not change, because
      only the paired devices know the shared secret, key, and sequence
      number to select the ISAAC result.

   To detect an on-path attacker attack when the session is in the Up
   state, implementations have two options.  They can choose to use:

   *  Test periodic strong authentication using a Poll sequence.  To
      perform a strong authentication, a Poll sequence SHOULD be
      initiated by the sender.  If a Fin is not received within the
      Detect Interval, the session has been compromised, and should be
      brought down.  The interval for initiating a Poll sequence can be
      configured depending on the capability of the system.

   *  Meticulous Keyed ISAAC as defined in
      [I-D.ietf-bfd-secure-sequence-numbers].

   Most packets transmitted on a BFD session are BFD Up packets.
   Strongly authenticating a small subset of these packets with a Poll
   sequence as described above, for example every one minute,
   significantly reduces the computational demand for the system while
   maintaining security of the session across the configured interval.

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1.1.  Requirements Language

   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 BCP 14 [RFC2119]
   [RFC8174] when, and only when, they appear in all capitals, as shown
   here.

1.2.  Note to RFC Editor

   This document uses several placeholder values throughout the
   document.  Please replace them as follows and remove this note before
   publication.

   RFC XXXX, where XXXX is the number assigned to this document at the
   time of publication.

   2024-05-05 with the actual date of the publication of this document.

1.3.  Terminology

   The following terms used in this document have been defined in BFD
   [RFC5880].

   *  Detect Multiplier

   *  Detection Time

   The following terms are introduced in this document.

      +=============+==============================================+
      | Term        | Meaning                                      |
      +=============+==============================================+
      | significant | State change, a demand mode change (to D     |
      | change      | bit) or a poll sequence change (P or F bit). |
      |             | Control packets that do not require a poll   |
      |             | sequence, such as bfd.RequiredMinRxInterval  |
      |             | bfd.RequiredMinTxInterval, or bfd.DetectMult |
      |             | are also considered as a significant change. |
      +-------------+----------------------------------------------+
      | configured  | Interval at which BFD control packets are    |
      | interval    | retried with a stronger authentication.      |
      +-------------+----------------------------------------------+

                                 Table 1

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2.  Authentication Mode

   The cryptographic authentication mechanisms specified in BFD
   [RFC5880] describes enabling and disabling of authentication as a one
   time operation.  As a security precaution, it mentions that
   authentication state be allowed to change at most once.  Once
   enabled, every packet must have Authentication Bit set and the
   associated Authentication Type appended.  In addition, it states that
   an implementation SHOULD NOT allow the authentication state to be
   changed based on the receipt of a BFD control packet.

   This document proposes that an authentication mode that permits both
   a strong authentication mode and a less expensive "optimized" mode to
   be used within the same BFD session.  This pairing of a strong and an
   optimized mode of authentication is carried in new BFD authentication
   types representing a given authentication type pairing.

   The proposal outlines which BFD control packets are required to be
   strongly authenticated.  A BFD control packet that fails
   authentication is discarded, or a BFD control packet that was
   supposed to be strongly authenticated, but was not; e.g. a
   significant change packet, is discarded.  However, there is no change
   to the state machine for BFD, as the decision of a significant change
   is still decided by how many valid consecutive packets were received.

   The following table summarizes when the Auth Type should be set with
   a Auth (strongly authenticated) or an OPT ("optimized")
   authentication type.  The table should be read with the column
   indicating the BFD state the receiver is currently in, and the row
   indicating the BFD state the receiver might transition to based on
   the BFD control packet received.  The intersection of the two
   indicates whether the received BFD control packet should have the
   Auth Type set to either Auth, or OPT.  The BFD state refers to the
   states in BFD state machine described in Section 6.2 of BFD
   [RFC5880].

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                Read   : On state change from <column> to <row>
                Auth   : Strongly authenticated BFD control packet
                OPT    : "Optimized" authentiation, as configured.
                n/a    : Invalid state transition.
                Select : Most packets "optimized" authentication.
                         Selective (periodic) packets strongly
                         authenticated.
               +--------+--------+--------+--------+
               |        | DOWN   | INIT   | UP     |
               +--------+--------+--------+--------+
               | DOWN   |  OPT   |  Auth  |  Auth  |
               +--------+--------+--------+--------+
               | INIT   |  Auth  |  OPT   |  n/a   |
               +--------+--------+--------+--------+
               | UP     |  Auth  |  Auth  | Select |
               +--------+--------+--------+--------+

                   Figure 1: Optimized Authentication Map

   In other words, the contents of an Up packet MUST NOT change aside
   from the authentication section without stronger authentication.

3.  Signaling Optimized Authentication

   When the Authentication Present (A) bit is set and the Auth Type is a
   type supporting Optimized BFD Authentication, the Auth Type signals a
   pairing of a strong authentication type and an optimized
   authentication type.  This pairing is advertised in a single Auth
   Type value in order to permit implementations to be aware that:

   *  Optimized BFD procedures will be in use.

   *  The pairing of the strong and optimized authentication mechanisms
      will be used for that session.

   *  The current strong or optimized mode will be carried as described
      below:

        0                   1                   2                   3
        0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |   Auth Type   |   Auth Len    |  Auth Key ID  |  Optimized    |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                   Authentication Specific Data                ~
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              Figure 2: Common BFD Authentication Section

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   The Meticulous Keyed MD5, Meticulous Keyed SHA-1, and Meticulous
   Keyed ISAAC authentication sections define the fourth octet as
   "Reserved".  This document repurposes the "Reserved" field as the
   "Optimized" field when used for authentication types for optimized
   BFD procedures.

   Optimized:

   1.  When using the strong authentication type for optimized BFD Auth
       Types.

   2.  When using the optimized authentication type for optimized BFD
       Auth Types.

   Authentication Specific Data: When using the strong authentication
   type, the remainder of the authentication section carries that type's
   data.

   For example, for Auth Type "Optimized MD5 Meticulous Keyed ISAAC
   Authentication" (type TBD):

   When Optimized is 1, the format of the authentication section is the
   same as Section 4.3 of [RFC5880], excepting that Auth Type is still
   TBD and that Reserved is set to 1.

   When Optimized is 2, the format of the authentication section is the
   same as Section 5 of [I-D.ietf-bfd-secure-sequence-numbers],
   excepting that Auth Type is still TBD and that Reserved is set to 2.

3.1.  Error Handling

   If the received BFD Control packet contains an optimized
   authentication type using these procedures and the Optimized field is
   not 1 or 2, then the received packet MUST be discarded.

4.  Optimized Authentication Operations

   As noted in Section 2, when using optimized BFD procedures, strong
   authentication is used in the BFD state machine to bring a BFD
   session to the Up state or to make any change of the BFD parameters
   as carried in the BFD Control packet when in the Up state.

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   Once the BFD session has reached the Up state, the BFD Up state MUST
   be signaled to the remote BFD system using the strong authentication
   for at least Detect Mult packets before switching to the optimized
   authentication mode.  This is to permit mechanisms such as Meticulous
   Keyed ISAAC for BFD Authentication
   [I-D.ietf-bfd-secure-sequence-numbers] to be bootstrapped before
   switching to optimized authentication.

   It is RECOMMENDED that when using optimized authentication that
   implementations switch from strong authentication to optimized
   authentication after sending at least Detect Mult packets.  In the
   circumstances where a BFD session successfully reaches the Up state
   with strong authentication, but there is problems with the optimized
   authentication, this will permit the remote system to tear down the
   session as quickly as possible.

   BFD sessions using optimized authentication that succeed in reaching
   the Up state using strong authentication and fail using the optimized
   authentication SHOULD bring the issue to the attention of the
   operator.  Further, implementations MAY wish to throttle session
   restarts.

   It is further RECOMMENDED that BFD implementations using optimized
   authentication defer notifying their client that the session has
   reached the Up state until it has transitioned to using the optimized
   authentication mode.  In the event where optimized authentication is
   failing in the protocol, this avoids propagating the failed
   transitions to optimized mode to the clients.

5.  Optimizing Authentication YANG Model

5.1.  Data Model Overview

   The YANG 1.1 [RFC7950] model defined in this document augments the
   "ietf-bfd" module to add configuration relevant to the management of
   the feature defined in this document.  In particular, it adds crypto
   algorithms that are described in this model, and in Meticulous Keyed
   ISAAC for BFD Authentication [I-D.ietf-bfd-secure-sequence-numbers].
   It adds a feature statement to enable optimized authentication.
   Finally, it adds a flag to enable optimized authentication, an
   interval value that specifies how often the BFD session should be re-
   authenticated once it is in the Up state, and the key chain that
   should be used in the Up state.

5.2.  Tree Diagram

   The tree diagram for the YANG modules defined in this document use
   annotations defined in YANG Tree Diagrams.  [RFC8340].

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   module: ietf-bfd-opt-auth

     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh
               /bfd-ip-sh:sessions/bfd-ip-sh:session
               /bfd-ip-sh:authentication:
       +--rw reauth-interval?   uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh
               /bfd-ip-mh:session-groups/bfd-ip-mh:session-group
               /bfd-ip-mh:authentication:
       +--rw reauth-interval?   uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-lag:lag
               /bfd-lag:sessions/bfd-lag:session/bfd-lag:authentication:
       +--rw reauth-interval?   uint32
     augment /rt:routing/rt:control-plane-protocols
               /rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls
               /bfd-mpls:session-groups/bfd-mpls:session-group
               /bfd-mpls:authentication:
       +--rw reauth-interval?   uint32

5.3.  The YANG Model

   This YANG module imports YANG Key Chain [RFC8177], A YANG Data Model
   for Routing Management (NMDA version) [RFC8349], and YANG Data Model
   for Bidirectional Forwarding Detection (BFD) [RFC9314].

   <CODE BEGINS> file "ietf-bfd-opt-auth@2024-05-05.yang"
   module ietf-bfd-opt-auth {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth";
     prefix "bfdoa";

     import ietf-routing {
       prefix "rt";
       reference
         "RFC 8349: A YANG Data Model for Routing Management
          (NMDA version)";
     }

     import ietf-bfd {
       prefix bfd;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
          Forwarding Detection.";
     }

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     import ietf-bfd-ip-sh {
       prefix bfd-ip-sh;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
          Forwarding Detection.";
     }

     import ietf-bfd-ip-mh {
       prefix bfd-ip-mh;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
          Forwarding Detection.";
     }

     import ietf-bfd-lag {
       prefix bfd-lag;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
          Forwarding Detection.";
     }

     import ietf-bfd-mpls {
       prefix bfd-mpls;
       reference
         "RFC 9314: YANG Data Model for Bidirectional
          Forwarding Detection.";
     }

     import ietf-key-chain {
       prefix key-chain;
       reference
         "RFC 8177: YANG Key Chain.";
     }

     organization
       "IETF BFD Working Group";

     contact
       "WG Web:   <http://tools.ietf.org/wg/bfd>
        WG List:  <rtg-bfd@ietf.org>

        Authors: Mahesh Jethanandani (mjethanandani@gmail.com)
                 Ashesh Mishra (mishra.ashesh@gmail.com)
                 Ankur Saxena (ankurpsaxena@gmail.com)
                 Manav Bhatia (mnvbhatia@google.com).";

     description

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       "This YANG module augments the base BFD YANG model to add
        attributes related to BFD Optimized Authentication.

        Copyright (c) 2024 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 Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC XXXX
        (https://www.rfc-editor.org/info/rfcXXXX); see the RFC itself
        for full legal notices.

        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 (RFC 2119) (RFC 8174) when, and only when,
        they appear in all capitals, as shown here.";

     revision "2024-05-05" {
       description
         "Initial Version.";
       reference
         "RFC XXXX: Optimizing BFD Authentication.";
     }

     feature optimized-auth {
       description
         "When enabled, this implementation supports optimized
          authentication as described in this document.";
     }

     identity null-auth {
       base key-chain:crypto-algorithm;
       description
         "BFD Null Auth type defined in this draft.";
       reference
         "RFC XXXX: BFD Stability.";
     }

     identity optimized-md5-meticulous-keyed-isaac {
       base key-chain:crypto-algorithm;
       description
         "BFD Optimized Authentication using Meticulous Keyed MD5 as the

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          strong authentication and Meticulous Keyed ISAAC Keyed as the
          'optimized' authentication.";
       reference
         "I-D.ietf-bfd-optimizing-authentication:
            Meticulous Keyed ISAAC for BFD Authentication.
          I-D.ietf-bfd-secure-sequence-numbers:
            Meticulous Keyed ISAAC for BFD Authentication.";
     }

     identity optimized-sha1-meticulous-keyed-isaac {
       base key-chain:crypto-algorithm;
       description
         "BFD Optimized Authentication using Meticulous Keyed SHA-1 as
         the strong authentication and Meticulous Keyed ISAAC Keyed as
         the 'optimized' authentication.";
       reference
         "I-D.ietf-bfd-optimizing-authentication:
            Meticulous Keyed ISAAC for BFD Authentication.
          I-D.ietf-bfd-secure-sequence-numbers:
            Meticulous Keyed ISAAC for BFD Authentication.";
     }

     augment "/rt:routing/rt:control-plane-protocols" +
             "/rt:control-plane-protocol/bfd:bfd/bfd-ip-sh:ip-sh" +
             "/bfd-ip-sh:sessions/bfd-ip-sh:session" +
             "/bfd-ip-sh:authentication" {
       leaf reauth-interval {
         type uint32;
         units "seconds";
         default "60";
         description
           "Interval of time after which a strong authentication
            should be enabled to prevent an on-path-attacker attack.
            Default is 1 minute.

            A value of zero means that we do not do periodic
            re-authorization using strong authentication.

            This value SHOULD have jitter applied to it to avoid
            self-synchronization during expensive authentication
            operations.";
       }

       description
         "Augment the 'authentication' container in BFD module to
          add attributes related to BFD optimized authentication.";
     }

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     augment "/rt:routing/rt:control-plane-protocols/" +
             "rt:control-plane-protocol/bfd:bfd/bfd-ip-mh:ip-mh/" +
             "bfd-ip-mh:session-groups/bfd-ip-mh:session-group/" +
             "bfd-ip-mh:authentication" {
       leaf reauth-interval {
         type uint32;
         units "seconds";
         default "60";
         description
           "Interval of time after which a strong authentication
            should be enabled to prevent an on-path attacker attack.
            Default is 1 minute.

            A value of zero means that we do not do periodic
            re-authorization using strong authentication.

            This value SHOULD have jitter applied to it to avoid
            self-synchronization during expensive authentication
            operations.";
       }

       description
         "Augment the 'authentication' container in BFD module to
          add attributes related to BFD optimized authentication.";
     }

     augment "/rt:routing/rt:control-plane-protocols/" +
             "rt:control-plane-protocol/bfd:bfd/bfd-lag:lag/" +
             "bfd-lag:sessions/bfd-lag:session/" +
             "bfd-lag:authentication" {
       leaf reauth-interval {
         type uint32;
         units "seconds";
         default "60";
         description
           "Interval of time after which a strong authentication
            should be enabled to prevent an on-path attacker attack.
            Default is 1 minute.

            A value of zero means that we do not do periodic
            re-authorization using strong authentication.

            This value SHOULD have jitter applied to it to avoid
            self-synchronization during expensive authentication
            operations.";
       }

       description

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         "Augment the 'authentication' container in BFD module to
          add attributes related to BFD optimized authentication.";
     }

     augment "/rt:routing/rt:control-plane-protocols/" +
             "rt:control-plane-protocol/bfd:bfd/bfd-mpls:mpls/" +
             "bfd-mpls:session-groups/bfd-mpls:session-group/" +
             "bfd-mpls:authentication" {
       leaf reauth-interval {
         type uint32;
         units "seconds";
         default "60";
         description
           "Interval of time after which a strong authentication
            should be enabled to prevent an on-path attacker attack.
            Default is 1 minute.

            A value of zero means that we do not do periodic
            re-authorization using strong authentication.

            This value SHOULD have jitter applied to it to avoid
            self-synchronization during expensive authentication
            operations.";
       }

       description
         "Augment the 'authentication' container in BFD module to
          add attributes related to BFD optimized authentication.";
     }
   }
   <CODE ENDS>

6.  IANA Considerations

   This documents requests two new authentication types, one URI, one
   YANG model, and an update to an existing IANA YANG model.

6.1.  Auth Type

   This document requests an update to the registry titled "BFD
   Authentication Types".  IANA is requested to assign two new BFD
   AuthType:

   *  Optimized MD5 Meticulous Keyed ISAAC Authentication
      [I-D.ietf-bfd-secure-sequence-numbers] (Part
      meticulous-keyed-isaac-authentication), with a suggested value of
      7.

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   *  Optimized SHA-1 Meticulous Keyed ISAAC Authentication
      [I-D.ietf-bfd-secure-sequence-numbers] (Part
      meticulous-keyed-isaac-authentication), with a suggested value of
      8.

6.2.  IETF XML Registry

   This document registers one URIs in the "ns" subregistry of the "IETF
   XML" registry [RFC3688].  Following the format in [RFC3688], the
   following registration is requested:

   URI: urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth
   Registrant Contact: The IESG
   XML: N/A, the requested URI is an XML namespace.

6.3.  The YANG Module Names Registry

   This document registers one YANG modules in the "YANG Module Names"
   registry [RFC6020].  Following the format in [RFC6020], the following
   registrations are requested:

   name:         ietf-bfd-opt-auth
   namespace:    urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth
   prefix:       bfdoa
   reference:    RFC XXXX

6.4.  Updated IANA Module

   This document also requests an update to an existing IANA YANG module
   described in Updated BFD IANA Module (Appendix A)

7.  Security Considerations

   The YANG module specified in this document defines a schema for data
   that is designed to be accessed via network management protocols such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].  The NETCONF Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

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   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., edit-config)
   to these data nodes without proper protection can have a negative
   effect on network operations.  Some of the subtrees and data nodes
   and their sensitivity/vulnerability are described here.

   *  'reauth-interval' specifies the interval in Up state, after which
      a strong authentication SHOULD be performed to prevent a Person-
      In-The-Middle (PITM) attack.  If this interval is set very low, or
      very high, then it will make optimization worthless.

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.

   There are no read-only data nodes defined in this model.

   Some of the RPC operations in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control access to these operations.

   There are no RPC operations defined in this model.

   The approach described in this document enhances the ability to
   authenticate a BFD session by taking away the onerous requirement
   that every BFD control packet be authenticated.  By authenticating
   packets that affect the state of the session, the security of the BFD
   session is maintained.  In this mode, packets that are a significant
   change but are not authenticated, are dropped by the system.
   Therefore, a malicious user that tries to inject a non-authenticated
   packet; e.g. with a Down state to take a session down will fail.
   That combined with the proposal of using sequence number defined in
   Meticulous Keyed ISAAC for BFD Authentication
   [I-D.ietf-bfd-secure-sequence-numbers] further enhances the security
   of BFD sessions.

8.  Contributors

   The authors of this document would like to acknowledge Reshad Rehman
   as a contributor to this document.

9.  References

9.1.  Normative References

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   [I-D.ietf-bfd-secure-sequence-numbers]
              DeKok, A., Jethanandani, M., Agarwal, S., Mishra, A., and
              A. Saxena, "Meticulous Keyed ISAAC for BFD
              Authentication", Work in Progress, Internet-Draft, draft-
              ietf-bfd-secure-sequence-numbers-13, 4 February 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-bfd-
              secure-sequence-numbers-13>.

   [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>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/info/rfc3688>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [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>.

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/info/rfc7950>.

   [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>.

   [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>.

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   [RFC8177]  Lindem, A., Ed., Qu, Y., Yeung, D., Chen, I., and J.
              Zhang, "YANG Data Model for Key Chains", RFC 8177,
              DOI 10.17487/RFC8177, June 2017,
              <https://www.rfc-editor.org/info/rfc8177>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/info/rfc8340>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/info/rfc8341>.

   [RFC8349]  Lhotka, L., Lindem, A., and Y. Qu, "A YANG Data Model for
              Routing Management (NMDA Version)", RFC 8349,
              DOI 10.17487/RFC8349, March 2018,
              <https://www.rfc-editor.org/info/rfc8349>.

   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/info/rfc8446>.

   [RFC9127]  Rahman, R., Ed., Zheng, L., Ed., Jethanandani, M., Ed.,
              Pallagatti, S., and G. Mirsky, "YANG Data Model for
              Bidirectional Forwarding Detection (BFD)", RFC 9127,
              DOI 10.17487/RFC9127, October 2021,
              <https://www.rfc-editor.org/info/rfc9127>.

   [RFC9314]  Jethanandani, M., Ed., Rahman, R., Ed., Zheng, L., Ed.,
              Pallagatti, S., and G. Mirsky, "YANG Data Model for
              Bidirectional Forwarding Detection (BFD)", RFC 9314,
              DOI 10.17487/RFC9314, September 2022,
              <https://www.rfc-editor.org/info/rfc9314>.

9.2.  Informative References

   [RFC1321]  Rivest, R., "The MD5 Message-Digest Algorithm", RFC 1321,
              DOI 10.17487/RFC1321, April 1992,
              <https://www.rfc-editor.org/info/rfc1321>.

   [RFC6151]  Turner, S. and L. Chen, "Updated Security Considerations
              for the MD5 Message-Digest and the HMAC-MD5 Algorithms",
              RFC 6151, DOI 10.17487/RFC6151, March 2011,
              <https://www.rfc-editor.org/info/rfc6151>.

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   [RFC6194]  Polk, T., Chen, L., Turner, S., and P. Hoffman, "Security
              Considerations for the SHA-0 and SHA-1 Message-Digest
              Algorithms", RFC 6194, DOI 10.17487/RFC6194, March 2011,
              <https://www.rfc-editor.org/info/rfc6194>.

   [SHA-1-attack1]
              Wang, X., Yin, Y., and H. Yu, "Finding Collisions in the
              Full SHA-1", 2005.

   [SHA-1-attack2]
              Wang, X., Yao, A., and F. Yao, "New Collision Search for
              SHA-1", 2005.

Appendix A.  Updated BFD IANA Module

   This section carries the updated IANA BFD Module, iana-bfd-types.yang
   module, first defined in YANG Data Model for Bidirectional Forward
   Detection (BFD) [RFC9127].  The updated module carries three new
   authentication type enum definitions, 'null' with a suggested value
   of 6, and 'optimized-md5-meticulous-keyed-isaac' with a suggested
   value of 7, and 'optimized-sha1-meticulous-keyed-isaac' with a
   suggested value of 8.  This module should replace the version that
   currently exists in the IANA registry.

   <CODE BEGINS> file "iana-bfd-types@2024-05-05.yang"
   module iana-bfd-types {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:iana-bfd-types";
     prefix iana-bfd-types;

     organization
       "IANA";
     contact
       "Internet Assigned Numbers Authority

        Postal: ICANN
                12025 Waterfront Drive, Suite 300
                Los Angeles, CA 90094-2536
                United States of America
        Tel:    +1 310 301 5800
        <mailto:iana@iana.org>";
     description
       "This module defines YANG data types for IANA-registered
        BFD parameters.

        This YANG module is maintained by IANA and reflects the
        'BFD Diagnostic Codes' and 'BFD Authentication Types'
        registries.

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        Copyright (c) 2021 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
        (https://trustee.ietf.org/license-info).

        This version of this YANG module is part of RFC 9127; see the
        RFC itself for full legal notices.";
     reference
       "RFC 9127: YANG Data Model for Bidirectional Forwarding
        Detection (BFD)";

     revision 2024-05-05 {
       description
         "Add NULL and Meticulous ISAAC authentication type.";
       reference
         "I-D.ietf-bfd-optimized-auth: Optimizing BFD Authentication.";
     }

     revision 2021-10-21 {
       description
         "Initial revision.";
       reference
         "RFC 9127: YANG Data Model for Bidirectional Forwarding
          Detection (BFD)";
     }

     /*
      * Type definitions
      */

     typedef diagnostic {
       type enumeration {
         enum none {
           value 0;
           description
             "No Diagnostic.";
         }
         enum control-expiry {
           value 1;
           description
             "Control Detection Time Expired.";
         }
         enum echo-failed {

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           value 2;
           description
             "Echo Function Failed.";
         }
         enum neighbor-down {
           value 3;
           description
             "Neighbor Signaled Session Down.";
         }
         enum forwarding-reset {
           value 4;
           description
             "Forwarding Plane Reset.";
         }
         enum path-down {
           value 5;
           description
             "Path Down.";
         }
         enum concatenated-path-down {
           value 6;
           description
             "Concatenated Path Down.";
         }
         enum admin-down {
           value 7;
           description
             "Administratively Down.";
         }
         enum reverse-concatenated-path-down {
           value 8;
           description
             "Reverse Concatenated Path Down.";
         }
         enum mis-connectivity-defect {
           value 9;
           description
             "Mis-connectivity defect.";
           reference
             "RFC 5880: Bidirectional Forwarding Detection (BFD)
              RFC 6428: Proactive Connectivity Verification, Continuity
              Check, and Remote Defect Indication for the MPLS
              Transport Profile";
         }
       }
       description
         "BFD diagnostic codes as defined in RFC 5880.  Values are
          maintained in the 'BFD Diagnostic Codes' IANA registry.

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          Range is 0 to 31.";
       reference
         "RFC 5880: Bidirectional Forwarding Detection (BFD)";
     }

     typedef auth-type {
       type enumeration {
         enum reserved {
           value 0;
           description
             "Reserved.";
         }
         enum simple-password {
           value 1;
           description
             "Simple Password.";
         }
         enum keyed-md5 {
           value 2;
           description
             "Keyed MD5.";
         }
         enum meticulous-keyed-md5 {
           value 3;
           description
             "Meticulous Keyed MD5.";
         }
         enum keyed-sha1 {
           value 4;
           description
             "Keyed SHA1.";
         }
         enum meticulous-keyed-sha1 {
           value 5;
           description
             "Meticulous Keyed SHA1.";
         }
         enum null {
           value 6;
           description
             "NULL Auth.";
         }
         enum optimized-md5-meticulous-keyed-isaac {
           value 7;
           description
             "BFD Optimized Authentication using Meticulous Keyed
              MD5 as the strong authentication and Meticulous Keyed
              ISAAC as the 'optimized' authentication.";

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         }
         enum optimized-sha1-meticulous-keyed-isaac {
           value 8;
           description
             "BFD Optimized Authentication using Meticulous Keyed
              SHA-1 as the strong authentication and Meticulous Keyed
              ISAAC as the 'optimized' authentication.";
         }
       }
       description
         "BFD authentication type as defined in RFC 5880.  Values are
          maintained in the 'BFD Authentication Types' IANA registry.
          Range is 0 to 255.";
       reference
         "RFC 5880: Bidirectional Forwarding Detection (BFD)";
     }
   }
   <CODE ENDS>

Appendix B.  Examples

   This section tries to show some examples in how the model can be
   configured.

B.1.  Single Hop BFD Configuration

   This example demonstrates how a Single Hop BFD session can be
   configured for optimized authentication.

   =============== NOTE: '\' line wrapping per RFC 8792 ===============

   <?xml version="1.0" encoding="UTF-8"?>
   <key-chains
       xmlns="urn:ietf:params:xml:ns:yang:ietf-key-chain">
     <key-chain>
       <name>bfd-auth-config</name>
       <description>"An example for BFD Optimized Auth configuration."\
   </description>
       <key>
         <key-id>55</key-id>
         <lifetime>
           <send-lifetime>
             <start-date-time>2017-01-01T00:00:00Z</start-date-time>
             <end-date-time>2017-02-01T00:00:00Z</end-date-time>
           </send-lifetime>
           <accept-lifetime>
             <start-date-time>2016-12-31T23:59:55Z</start-date-time>
             <end-date-time>2017-02-01T00:00:05Z</end-date-time>

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           </accept-lifetime>
         </lifetime>
         <crypto-algorithm xmlns:opt-auth=
         "urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth">opt-auth:opti\
   mized-sha1-meticulous-keyed-isaac</crypto-algorithm>
         <key-string>
           <keystring>testvector</keystring>
         </key-string>
       </key>
     </key-chain>
   </key-chains>
   <interfaces
       xmlns="urn:ietf:params:xml:ns:yang:ietf-interfaces"
       xmlns:if-type="urn:ietf:params:xml:ns:yang:iana-if-type">
     <interface>
       <name>eth0</name>
       <type>if-type:ethernetCsmacd</type>
     </interface>
   </interfaces>
   <routing
       xmlns="urn:ietf:params:xml:ns:yang:ietf-routing"
       xmlns:bfd-types="urn:ietf:params:xml:ns:yang:ietf-bfd-types"
       xmlns:iana-bfd-types="urn:ietf:params:xml:ns:yang:iana-bfd-type\
   s"
       xmlns:opt-auth="urn:ietf:params:xml:ns:yang:ietf-bfd-opt-auth">
     <control-plane-protocols>
       <control-plane-protocol>
         <type>bfd-types:bfdv1</type>
         <name>name:BFD</name>
         <bfd xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd">
           <ip-sh xmlns="urn:ietf:params:xml:ns:yang:ietf-bfd-ip-sh">
             <sessions>
               <session>
                 <interface>eth0</interface>
                 <dest-addr>2001:db8:0:113::101</dest-addr>
                 <desired-min-tx-interval>10000</desired-min-tx-interv\
   al>
                 <required-min-rx-interval>
                   10000
                 </required-min-rx-interval>
                 <authentication>
                   <opt-auth:reauth-interval>30</opt-auth:reauth-inter\
   val>
                 </authentication>
               </session>
             </sessions>
           </ip-sh>
         </bfd>

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       </control-plane-protocol>
     </control-plane-protocols>
   </routing>

Authors' Addresses

   Mahesh Jethanandani
   Kloud Services
   United States of America
   Email: mjethanandani@gmail.com

   Ashesh Mishra
   Aalyria Technologies
   Email: ashesh@aalyria.com

   Ankur Saxena
   Ciena Corporation
   3939 N 1st Street
   San Jose, CA 95134
   United States of America
   Email: ankurpsaxena@gmail.com

   Manav Bhatia
   Google
   Doddanekkundi
   Bangalore 560048
   India
   Email: mnvbhatia@google.com

   Jeffrey Haas
   Juniper Networks
   Email: jhaas@pfrc.org

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