I2NSF                                                     R. Marin-Lopez
Internet-Draft                                           G. Lopez-Millan
Intended status: Standards Track                    University of Murcia
Expires: April 25, September 12, 2019                         F. Pereniguez-Garcia
                                               University Defense Center
                                                          March 11, 2019                                 October 22, 2018

     Software-Defined Networking (SDN)-based IPsec Flow Protection
             draft-ietf-i2nsf-sdn-ipsec-flow-protection-03
             draft-ietf-i2nsf-sdn-ipsec-flow-protection-04

Abstract

   This document describes how providing IPsec-based flow protection by
   means of a Software-Defined Network (SDN) controller (aka.  Security
   Controller) and establishes the requirements to support this service.
   It considers two main well-known scenarios in IPsec: (i) gateway-to-
   gateway and (ii) host-to-host.  The SDN-based service described in
   this document allows the distribution and monitoring of IPsec
   information from a Security Controller to one or several flow-based
   Network Security Function (NSF).  The NSFs implement IPsec to protect
   data traffic between network resources with IPsec.

   The document focuses in the NSF Facing Interface by providing models
   for Configuration and State data model required to allow the Security
   Controller to configure the IPsec databases (SPD, SAD, PAD) and IKEv2
   to establish security associations with a reduced intervention of the
   network administrator.

Status of This Memo

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Requirements Language . . . . . . . . . . . . . . . . . . . .   4
   3.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   5   4
   4.  Objectives  . . . . . . . . . . . . . . . . . . . . . . . . .   6
   5.  SDN-based IPsec management description  . . . . . . . . . . .   6
     5.1.  Case 1:  IKE case: IKE/IPsec in the NSF  . . . . . . . . . . . . . .   6
       5.1.1.  Interface Requirements for Case 1 . IKE case . . . . . . . . .   7
     5.2.  Case 2:  IKE-less case: IPsec (no IKEv2) in the NSF  . . . . . . . . . . .   7   8
       5.2.1.  Interface Requirements for Case 2 . . . . IKE-less case  . . . . . .   8
     5.3.  Case 1  IKE case vs Case 2  . . . . IKE-less case . . . . . . . . . . . . . . . .   8   9
       5.3.1.  Rekeying process  . . . . . . . . . . . . . . . . . .   9  10
       5.3.2.  NSF state loss  . . . . . . . . . . . . . . . . . . .  10  11
       5.3.3.  NAT Traversal . . . . . . . . . . . . . . . . . . . .  10  12
   6.  YANG configuration data models  . . . . . . . . . . . . . . .  11  12
     6.1.  Security Policy Database (SPD) Model  IKE case model  . . . . . . . . . .  11
     6.2.  Security Association Database (SAD) Model . . . . . . . .  13
     6.3.  Peer Authorization Database (PAD) Model . . .  13
     6.2.  IKE-less case model . . . . . . . .  16
     6.4.  Internet Key Exchange (IKEv2) Model . . . . . . . . . . .  17  16
   7.  Use cases examples  . . . . . . . . . . . . . . . . . . . . .  19  21
     7.1.  Host-to-Host  Host-to-host or Gateway-to-gateway gateway-to-gateway under the same
           controller  . . . . . . . . . . . . . . . . . . . . . . .  19  21
     7.2.  Host-to-Host  Host-to-host or Gateway-to-gateway gateway-to-gateway under different
           Security
           security controllers  . . . . . . . . . . . . . . . . . .  22  23
   8.  Implementation notes  Security Considerations . . . . . . . . . . . . . . . . . . .  25
     8.1.  IKE case  . .  24
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  25
     9.1.  Case 1 . . .  26
     8.2.  IKE-less case . . . . . . . . . . . . . . . . . . . . . .  26
     9.2.  Case 2
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  27
   10. References  . . .  26
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . .  27
   11.
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  27
     10.2.  Informative References . . . . . . . . .  27
     11.1.  Normative References . . . . . . . .  28
   Appendix A.  Appendix A: Common YANG model for IKE and IKEless
                cases  . . . . . . . . . . . . .  27
     11.2.  Informative References . . . . . . . . . .  31
   Appendix B.  Appendix B: YANG model for IKE case  . . . . . . .  27 .  37
   Appendix A. C.  Appendix A: C: YANG model IPsec Configuration data for IKE-less case . . . .  30 . .  43
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  48  49

1.  Introduction

   Software-Defined Networking (SDN) is an architecture that enables
   users to directly program, orchestrate, control and manage network
   resources through software.  SDN paradigm relocates the control of
   network resources to a dedicated network element, namely SDN
   controller.  The SDN controller manages and configures the
   distributed network resources and provides an abstracted view of the
   network resources to the SDN applications.  The SDN application can
   customize and automate the operations (including management) of the
   abstracted network resources in a programmable manner via this
   interface [RFC7149][ITU-T.Y.3300]
   [ONF-SDN-Architecture][ONF-OpenFlow].

   Typically, traditional IPsec VPN concentrators and, in general,
   entities (i.e. hosts or security gateways) supporting IKE/IPsec, must
   be configured directly by the administrator.  This makes the IPsec
   security association (SA) management difficult and generates

   Recently, several network scenarios are considering a lack
   of flexibility, specially if the number centralized way
   of managing different security policies and SAs aspects.  For example, Software-
   Defined WANs (SD-WAN) advocates to handle is high.  With manage IPsec SAs from a
   centralized point.  Therefore, with the growth of SDN-based scenarios
   where network resources are deployed in an autonomous manner, a
   mechanism to manage IPsec SAs according to the SDN architecture
   becomes more relevant.  Thus, the SDN-based service described in this
   document will autonomously deal with IPsec SAs management. management following a
   SDN paradigm.

   An example of usage can be the notion of Software Defined WAN (SD-
   WAN), SDN extension providing a software abstraction to create secure
   network overlays over traditional WAN and branch networks.  SD-WAN is
   based on IPsec as underlying security protocol and aims to provide
   flexible, automated, fast deployment and on-demand security network
   services.

   IPsec architecture [RFC4301] defines a clear separation between the
   processing to provide security services to IP packets and the key
   management procedures to establish the IPsec security associations.
   In this document, we define a service where the key management
   procedures can be carried by an external entity: the Security
   Controller.

   First, this document exposes the requirements to support the
   protection of data flows using IPsec [RFC4301].  We have considered
   two general cases:

   1)  IKE case.  The Network Security Function (NSF) implements the
       Internet Key Exchange (IKE) protocol and the IPsec databases: the
       Security Policy Database (SPD), the Security Association Database
       (SAD) and the Peer Authorization Database (PAD).  The Security
       Controller is in charge of provisioning the NSF with the required
       information to IKE, the SPD and the PAD.

   2)  IKE-less case.  The NSF only implements the IPsec databases (no
       IKE implementation).  The Security Controller will provide the
       required parameters to create valid entries in the SPD and the
       SAD into the NSF.  Therefore, the NSF will have only support for
       IPsec while automated key management functionality is moved to
       the controller.

   In both cases, an interface/protocol is required to carry out this
   provisioning in a secure manner between the Security Controller and
   the NSF.  In particular, Case 1 IKE case requires the provision of SPD and
   PAD entries and the IKE credential and information related with the
   IKE negotiation (e.g.  IKE_SA_INIT);  IKE_SA_INIT), and Case 2 IKE-less case requires the
   management of SPD and SAD entries.  Based on YANG models in
   [netconf-vpn] and [I-D.tran-ipsecme-yang], RFC 4301 [RFC4301] and RFC
   7296 [RFC7296] this document defines the required interfaces with a
   YANG model for configuration and state data for IKE, PAD, SPD and SAD
   (see Appendix A. A, Appendix B and Appendix C).

   This document considers two typical scenarios to manage autonomously
   IPsec SAs: gateway-to-gateway and host-to-host [RFC6071].  The
   analysis of the host-to-gateway (roadwarrior) scenario is TBD. out of
   scope of this document.  In these cases, host or gateways or both may
   act as NSFs.  Finally, it also discusses the situation where two NSFs
   are under the control of two different Security Controllers.

   NOTE: This work pays attention to the challenge "Lack of Mechanism
   for Dynamic Key Distribution to NSFs" defined in
   [I-D.ietf-i2nsf-problem-and-use-cases] [RFC8192] in the
   particular case of the establishment and management of IPsec SAs.  In
   fact, this I-D could be considered as a proper use case for this
   particular challenge in
   [I-D.ietf-i2nsf-problem-and-use-cases]. [RFC8192].

2.  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 RFC 2119 [RFC2119].
   When these words appear in lower case, they have their natural
   language meaning.

3.  Terminology

   This document uses the terminology described in [RFC7149], [RFC4301],
   [ITU-T.Y.3300], [ONF-SDN-Architecture], [ONF-OpenFlow],

   [ITU-T.X.1252], [ITU-T.X.800] and [I-D.ietf-i2nsf-terminology].  In
   addition, the following terms are defined below:

   o  Software-Defined Networking.  A set of techniques enabling to
      directly program, orchestrate, control, and manage network
      resources, which facilitates the design, delivery and operation of
      network services in a dynamic and scalable manner [ITU-T.Y.3300].

   o  Flow/Data Flow.  Set of network packets sharing a set of
      characteristics, for example IP dst/src values or QoS parameters.

   o  Security Controller.  A Controller is a management Component component that
      contains control plane functions to manage and facilitate
      information sharing, as well as execute security functions.  In
      the context of this document, it provides IPsec management
      information.

   o  Network Security Function (NSF).  Software that provides a set of
      security-related services.

   o  Flow-based NSF.  A NSF that inspects network flows according to a
      set of policies intended for enforcing security properties.  The
      NSFs considered in this document falls into this classification.

   o  Flow-based Protection Policy.  The set of rules defining the
      conditions under which a data flow MUST be protected with IPsec,
      and the rules that MUST be applied to the specific flow.

   o  Internet Key Exchange (IKE) v2 Protocol to establish IPsec
      Security Associations (SAs).  It requires information about the
      required authentication method (i.e. preshared keys), raw RSA/ECDSA keys or X.509
      certificates), DH groups, modes and algorithms for IKE SA
      negotiation, etc.

   o  Security Policy Database (SPD).  It includes information about
      IPsec policies direction (in, out), local and remote addresses,
      inbound and outboud SAs, etc.

   o  Security Associations Database (SAD).  It includes information
      about IPsec SAs, such as SPI, destination addresses,
      authentication and encryption algorithms and keys to protect IP
      flow.
      flows.

   o  Peer Authorization Database (PAD).  It provides the link between
      the SPD and a security association management protocol such as IKE
      or the SDN-based solution described in this document.

4.  Objectives

   o  To describe the architecture for the SDN-based IPsec management,
      which implements a security service to allow the establishment and
      management of IPsec security associations from a central point point, in
      order to protect specific data flows.

   o  To define the interfaces required to manage and monitor the IPsec
      Security Associations in the NSF from a Security Controller.  YANG
      models are defined for configuration and state data for IPsec
      management.

5.  SDN-based IPsec management description

   As mentioned in Section 1, two cases are considered:

5.1.  Case 1:  IKE case: IKE/IPsec in the NSF

   In this case the NSF ships an IKEv2 implementation besides the IPsec
   support.  The Security Controller is in charge of managing and
   applying SPD and PAD entries (deriving and delivering IKE Credentials
   such as a pre-shared key, certificates, etc.), and applying other IKE
   configuration parameters (e.g.  IKE_SA_INIT algorithms) to the NSF
   for the IKE negotiation.

   With these entries, the IKEv2 implementation can operate to establish
   the IPsec SAs.  The application (administrator) establishes the IPsec
   requirements and information about the end points information
   (through the Client Facing Interface), Interface, [RFC8192]), and the Security
   Controller translates those requirements into IKE, SPD and PAD
   entries that will be installed into the NSF (through the NSF Facing
   Interface).  With that information, the NSF can just run IKEv2 to
   establish the required IPsec SA (when the data flow needs
   protection).  Figure 1 shows the different layers and corresponding
   functionality.

                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                +-------------------------------------------+
                |IPsec Management/Orchestration Application | Client or
                |          I2NSF Client                     | App Gateway
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                +-------------------------------------------+
                                        |    Client Facing Interface
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                +-------------------------------------------+
       Vendor   |             Application Support           |
       Facing<->+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       Facing<->|-------------------------------------------| Security
       Interface| IKE Credential,PAD and SPD entries Distr. | Controller
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                +-------------------------------------------+
                                        |       NSF Facing Interface
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                +-------------------------------------------+
                |                 I2NSF Agent               |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                |-------------------------------------------| Network
                |   IKE    |      IPsec(SPD,PAD)            | Security
                +-------------------------------------------+
                |-------------------------------------------| Function
                |         Data Protection and Forwarding    |
                +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
                +-------------------------------------------+

                 Figure 1: Case 1: IKE case: IKE/IPsec in the NSF

5.1.1.  Interface Requirements for Case 1 IKE case

   SDN-based IPsec flow protection services provide dynamic and flexible
   management of IPsec SAs in flow-based NSF.  In order to support this
   capability in case 1, IKE case, the following interface requirements are
   to be met:

   o  A YANG data model for Configuration configuration data for IKEv2, SPD and PAD.

   o  A YANG data model for State state data for IKE, SPD, PAD PAD, SPD and SAD (NOTE:
      the SAD entries are created in runtime by IKEv2.)

   o  In scenarios where multiple controllers are implicated, SDN-based
      IPsec management services may require a mechanism to discover
      which Security Controller is managing a specific NSF.  Moreover,
      an east-west interface [RFC7426] is required to exchange IPsec-related IPsec-
      related information.  For example, if two gateways need to
      establish an IPsec SA and both are under the control of two
      different controllers then both Security Controllers need to
      exchange information to properly configure their own gateways.
      That is, the may need to agree on whether IKEv2 authentication
      will be based on raw public keys or pre-shared keys.  In case of
      using pre-shared keys they will have to agree in the PSK.

5.2.  Case 2:  IKE-less case: IPsec (no IKEv2) in the NSF

   In this case, the NSF does not deploy IKEv2 and, therefore, the
   Security Controller has to perform the IKE security functions and
   management of IPsec SAs by populating and monitoring managing the SPD and the
   SAD.

              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

              +-----------------------------------------+
              |   IPsec Management  Application         | Client or
              |               I2NSF Client              | App Gateway
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              +-----------------------------------------+
                                      |   Client Facing Interface
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              +-----------------------------------------+
        Vendor|             Application Support         |
     Facing<->+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     Facing<->|-----------------------------------------| Security
     Interface|      SPD, SAD and PAD Entries Distr.    | Controller
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              +-----------------------------------------+
                                      |   NSF Facing Interface
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              +-----------------------------------------+
              |              I2NSF Agent                | Network
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |-----------------------------------------| Security
              |            IPsec (SPD,SAD)              | Function (NSF)
              +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
              |-----------------------------------------|
              |     Data Protection and Forwarding      |
              +-----------------------------------------+

            Figure 2: Case 2: IKE-less case: IPsec (no IKE) in the NSF

   As shown in Figure 2, applications for flow protection run on the top
   of the Security Controller.  When an administrator enforces flow-
   based protection policies through the Client Facing Interface, the
   Security Controller translates those requirements into SPD and SAD
   entries, which are installed in the NSF.  PAD entries are not
   required since there is no IKEv2 in the NSF.

5.2.1.  Interface Requirements for Case 2 IKE-less case

   In order to support case 2, the IKE-less case, the following requirements are
   to be met:

   o  A YANG data model for Configuration configuration data for SPD and SAD.

   o  A YANG data model for State state data for SPD and SAD.

   o  In scenarios where multiple controllers are implicated, SDN-based
      IPsec management services may require a mechanism to discover
      which Security Controller is managing a specific NSF.  Moreover,
      an east-west interface [RFC7426] is required to exchange IPsec-related IPsec-
      related information.  NOTE: A possible east-west protocol for this
      IKE-less case could be IKEv2.  However, this needs to be explore
      since the IKEv2 peers would be the Security Controllers.

   Specifically, the IKE-less case assumes that the SDN controller has
   to perform some security functions that IKEv2 typically does, namely
   (non-exhaustive):

   o  IV generation.

   o  prevent counter resets for same key.

   o  Generation of pseudo-random cryptographic keys for the IPsec SAs.

   o  Rekey of the IPsec SAs based on notification from the NSF (i.e.
      expire).

   o  Generation of the IPsec SAs when required based on notifications
      (i.e. sadb_acquire).

   o  NAT Traversal discovery and management.

   Additionally to these functions, another set of tasks must be
   performed by the Controller (non-exhaustive list):

   o  SPI random generation.

   o  Cryptographic algorithm/s selection.

   o  Usage of extended sequence numbers.

   o  Establishment of proper traffic selectors.

5.3.  Case 1  IKE case vs Case 2

   Case 1 IKE-less case

   IKE case MAY be easier to deploy than Case 2 IKE-less case because current
   gateways typically have an IKEv2/IPsec implementation.  Moreover
   hosts can install easily an IKE implementation.  As downside, the NSF
   needs more resources to hold IKEv2.  Moreover, the IKEv2
   implementation needs to implement an interface so that the I2NSF
   Agent can interact with them.

   Alternatively, Case 2 IKE-less case allows lighter NSFs (no IKEv2
   implementation), which benefits the deployment in constrained NSFs.
   Moreover, IKEv2 does not need to be performed in gateway-to-gateway
   and host-to-host scenarios under the same Security Controller (see
   Section 7.1).  On the contrary, the overload of creating fresh IPsec
   SAs is shifted to the Security Controller since IKEv2 is not in the
   NSF.  As a consequence, this may result in a more complex
   implementation in the controller side.

5.3.1.  Rekeying process

   For case 1, the rekeying process is carried out by IKEv2, following
   the configuration defined in the SPD.

   For case 2,  This overload may create some
   scalability issues when the Security Controller needs to take care number of NSFs is high.

   In general, literature around SDN-based network management using a
   centralized SDN controller is aware about scalability issues and
   solutions have been already provided (e.g. hierarchical SDN
   controllers; having multiple replicated SDN controllers, etc).  In
   the context of IPsec management, one straight way to reduce the
   overhead and the potential scalability issue in the Security
   Controller is to apply IKE case, described in this document, since
   the IPsec SAs are managed between NSFs without the involvement of the
   Security Controller at all, except by the initial IKE configuration
   provided by the Security Controller.  Other option with IKE-less is
   to use techniques already seen in SDN world such as, for example,
   hierarchical SDN controllers.  Other solutions, such as Controller-
   IKE [I-D.carrel-ipsecme-controller-ike], have proposed that NSFs
   provide their DH public keys to the Security Controller, so that the
   Security Controller distributes all public keys to all peers.  All
   peers can calculate a unique pairwise secret for each other peer and
   there is no inter-NSF messages.  A re-key mechanism is further
   described in [I-D.carrel-ipsecme-controller-ike].

   In terms of security, IKE case provides better security properties
   than IKE-less case, as we discuss in section Section 8.  The main
   reason is that the Security Controller is not able to observe any
   session keys generated for the IPsec SAs because IKEv2 is in charge
   of negotiating the IPsec SAs.

5.3.1.  Rekeying process

   For IKE case, the rekeying process is carried out by IKEv2, following
   the information defined in the SPD and SAD.

   For IKE-less case, the Security Controller needs to take care of the
   rekeying process.  When the IPsec SA is going to expire (e.g.  IPsec
   SA soft lifetime), it has to create a new IPsec SA and remove the old
   one.  This rekeying process starts when the Security Controller
   receives a sadb_expire notification or it decides so, based on
   lifetime state data obtained from the NSF.

   To explain the rekeying process between two IPsec peers A and B, let
   assume that SPIa1 identifies the inbound SA in A and SPIb1 the
   inbound SA in B.

   1.  The Security Controller chooses two random values as SPI for the
       new inbound SAs: for example, SPIa2 for A and SPIb2 for B.  These
       numbers MUST not be in conflict with any IPsec SA in A or B.
       Then,the

       Then, the Security Controller creates an inbound SA with SPIa2 in
       A and another inbound SA in B with SPIb2.  It can send this
       information simultenously simultaneously to A and B.

   2.  Once the Security Controller receives confirmation from A and B,
       inbound SA are correctly installed.  Then it proceeds to send in
       parallel to A and B the outbound SAs: it sends the outbound SA to
       A with SPIb2 and the outbound SA to B with SPIa2.  At this point
       the new IPsec SA is ready.

   3.  The  Once the Security Controller receives confirmation from A and B,
       that the outbound SAs have been installed, the Security
       Controller deletes the old IPsec SAs from A (inbound SPIa1 and
       outbound SPIb1) and B (outbound SPIa1 and inbound SPIb1) in
       parallel.

5.3.2.  NSF state loss

   If one of the NSF restarts, it may lose part or all  It is worth noting that if the IPsec state
   (affected NSF).  By default, implementation
       can itself detect traffic on the new IPsec SA, and it can delete
       the old IPsec SA itself without instruction from the Security
       Controller, then this step 3 is not required.

5.3.2.  NSF state loss

   If one of the NSF restarts, it will lose the IPsec state (affected
   NSF).  By default, the Security Controller can assume that all the
   state has been lost and therefore it will have to send IKEv2, SPD and
   PAD information to the NSF in case 1 IKE case, and SPD and SAD information
   in case 2. IKE-less case.

   In both cases, the Security Controller MUST be is aware of the affected NSF
   (e.g. the NETCONF/TCP connection is broken with the affected NSF,
   it the
   Security Controller is receiving bad_spi sadb_bad-spi notification from a
   particular NSF, etc...). etc.).  Moreover, the Security Controller MUST have has a
   register about all the NSFs that have IPsec SAs with the affected
   NSF.  Therefore, it knows the affected IPsec SAs.

   In Case 1, IKE case, the Security Controller will configure the affected NSF
   with the new IKEv2, SPD and PAD information.  It has also to send new
   parameters (e.g. a new fresh PSK) PSK for authentication) to the NSFs
   which have IKEv2 SAs and IPsec SAs with the affected NSF.  It can
   also instruct the affected NSF to send IKEv2 INITIAL_CONTACT (It is TBD in the model). INITIAL_CONTACT.
   Finally, the Security Controller will instruct the affected NSF to
   start the IKEv2 negotiation with the new configuration.

   In Case 2, IKE-less case, if the Security Controller detects that a NSF has
   lost the IPsec SAs (e.g. it reboots) it will follow similar steps delete the old IPsec SAs
   of the non-failed nodes established with the failed node (step 1).
   This prevents the non-failed nodes from leaking plaintext.  If the
   failed node comes to rekey: live, the steps 1 Security Controller will configure the
   new inbound IPsec SAs between the failed node and 2 remain equal but all the step 3 will be slightly
   different.  For example, if we assume that NSF B has lost its state, nodes the
   failed was talking to (step 2).  After these inbound IPsec SAs have
   been established, the Security Controller MUST only delete can configure the old outbound
   IPsec SAs from A in
   step 3. (step 3).

   Nevertheless other more optimized options can be considered (e.g.
   making iKEv2 IKEv2 configuration permanent between reboots).

5.3.3.  NAT Traversal

   In case 1, IKE case, IKEv2 already owns a mechanism to detect whether some of
   the peers or both are located behind a NAT.  If there is a NAT
   network configured between two peers, it is required to activate the
   usage of UDP or TCP/TLS encapsulation of ESP packets ([RFC3948], [RFC8229])
   [RFC8229]).  Note that the usage of TRANSPORT mode when NAT is
   required is forbidden in this specification.

   On the contrary, IKE-less case 2 does not have any protocol in the NSFs
   to detect whether they are located behind a NAT or not.  However, the
   SDN paradigm generally assumes the Security Controller has a view of
   the network it controls.  This view is built either requesting
   information to the NSFs under its control, or because these NSFs
   inform to the Security Controller.  Based on this information, the
   Security Controller can guess if there is a NAT configured between
   two hosts, and apply the required policies to both NSFs besides
   activating the usage of UDP or TCP/TLS encapsulation of ESP packets
   ([RFC3948], [RFC8229]).

   For example, the Security Controller could directly request the NSF
   for specific data such as networking configuration, NAT support, etc.
   Protocols such as NETCONF or SNMP can be used here.  For example, RFC
   7317 [RFC7317] provides a YANG data model for system management or
   [I-D.sivakumar-yang-nat]
   [I-D.ietf-opsawg-nat-yang] a data model for NAT management.  The
   Security Controller can use this NETCONF module with a gateway to
   collect NAT information or even configure a NAT.  In any case, if
   this NETCONF module is not available and the Security Controller
   cannot know if a host is behind a NAT or not, then IKE case should be
   the right choice and not the IKE-less.

6.  YANG configuration data models

   In order to support IKE case 1 and IKE-less case 2 we have modelled the
   different parameters and values that must be configured to manage
   IPsec SAs.  Specifically, case 1 IKE requires modelling modeling IKEv2, SPD and PAD
   while IKE-less case
   2 requires configuration models for the SPD and
   SAD.  A single YANG file represents
   both cases though some part of the models are selectively activated
   depending a feature  We have defined in the YANG file.  For example, the three models: ietf-ipsec-common (Appendix A),
   ietf-ipsec-ike (Appendix B, IKE
   configuration is not enabled in case 2.

   In case), ietf-ipsec-ikeless
   (Appendix C, IKE-less case).  Since the following, model ietf-ipsec-common has
   only typedef and groupings common to the other modules, in the
   following we summarize, by using only show a tree representation, simplified view of the
   different configuration ietf-ipsec-ike and state data
   ietf-ipsec-ikeless models.

6.1.  IKE case model

   The complete YANG
   configuration data model is related to IKEv2 has been extracted from reading IKEv2
   standard in Appendix A

6.1.  Security Policy Database (SPD) Model [RFC7296], and observing some open source
   implementations, such as Strongswan or Libreswan.

   The definition of this the PAD model has been extracted from the
   specification in section 4.4.1 and Appendix D 4.4.3 in [RFC4301] (NOTE: We have observed
   that many implementations integrate PAD configuration as part of the
   IKEv2 configuration.)

module: ietf-ipsec-ike
  +--rw spd ikev2
     +--rw pad
     |  +--rw spd-entry* [rule-number] pad-entry* [pad-entry-id]
     |     +--rw rule-number pad-entry-id                   uint64
     |     +--rw priority?               uint32 (identity)?
     |     +--rw names* [name]     |  +--:(ipv4-address)
     |  +--rw name-type?   ipsec-spd-name     |  |  +--rw name         string ipv4-address?            inet:ipv4-address
     |     +--rw condition     |  +--:(ipv6-address)
     |  +--rw traffic-selector-list* [ts-number]     |  |  +--rw ts-number              uint32 ipv6-address?            inet:ipv6-address
     |     |     +--rw direction?             ipsec-traffic-direction  +--:(fqdn-string)
     |     |  |  +--rw local-addresses* [start end] fqdn-string?             inet:domain-name
     |     |  +--:(rfc822-address-string)
     |     |  |  +--rw start    inet:ip-address rfc822-address-string?   string
     |     |  +--:(dnX509)
     |  +--rw end      inet:ip-address     |  |  +--rw remote-addresses* [start end] dnX509?                  string
     |     |  +--:(id_key)
     |     |  |  +--rw start    inet:ip-address id_key?                  string
     |     |  +--:(id_null)
     |     |  |  +--rw end      inet:ip-address id_null?                 empty
     |     |  +--:(user_fqdn)
     |     |     +--rw next-layer-protocol*   ipsec-next-layer-proto user_fqdn?               string
     |     +--rw my-identifier                  string
     |     +--rw local-ports* [start end] pad-auth-protocol?             auth-protocol-type
     |     +--rw auth-method
     |        +--rw auth-m?              auth-method-type
     |        +--rw start    inet:port-number eap-method
     |        |  +--rw eap-type?   uint8
     |        +--rw end      inet:port-number pre-shared
     |        |  +--rw remote-ports* [start end] secret?   yang:hex-string
     |        +--rw digital-signature
     |           +--rw ds-algorithm?     signature-algorithm-t
     |           +--rw start    inet:port-number raw-public-key?   yang:hex-string
     |           +--rw key-data?         string
     |           +--rw key-file?         string
     |           +--rw end      inet:port-number ca-data*          string
     |           +--rw ca-file?          string
     |           +--rw selector-priority?     uint32 cert-data?        string
     |           +--rw processing-info cert-file?        string
     |           +--rw crl-data?         string
     |           +--rw action          ipsec-spd-operation crl-file?         string
     |           +--rw oscp-uri?         inet:uri
     +--rw ike-conn-entry* [conn-name]
     |  +--rw ipsec-sa-cfg conn-name                            string
     |  +--rw autostartup                          type-autostartup
     |  +--rw pfp-flag? initial-contact?                     boolean
     |  +--rw version?                             enumeration
     |  +--rw extSeqNum? ike-fragmentation?                   boolean
     |     |  +--rw seqOverflow?         boolean ike-sa-lifetime-hard
     |  |  +--rw statefulfragCheck?   boolean time?      yang:timestamp
     |  |  +--rw security-protocol?   ipsec-protocol idle?      yang:timestamp
     |  |  +--rw mode?                ipsec-mode bytes?     uint32
     |  |  +--rw ah-algorithms packets?   uint32
     |  +--rw ike-sa-lifetime-soft
     |  |  +--rw ah-algorithm*   integrity-algorithm-t time?      yang:timestamp
     |  |  +--rw esp-algorithms
                        | idle?      yang:timestamp
     |  |  +--rw authentication*   integrity-algorithm-t
                        | bytes?     uint32
     |  |  +--rw encryption*       encryption-algorithm-t packets?   uint32
     |  |  +--rw tunnel action?    ic:lifetime-action
     |  +--rw ike-sa-authalg*                      ic:integrity-algorithm-t
     |  +--rw local?          inet:ip-address ike-sa-encalg*                       ic:encryption-algorithm-t
     |  +--rw dh_group                             uint32
     |  +--rw remote?         inet:ip-address half-open-ike-sa-timer?              uint32
     |  +--rw half-open-ike-sa-cookie-threshold?   uint32
     |  +--rw bypass-df?      boolean local
     |  |  +--rw bypass-dscp?    boolean
                        | local-pad-id?   uint64
     |  +--rw dscp-mapping?   yang:hex-string remote
     |  |  +--rw ecn?            boolean remote-pad-id?   uint64
     |  +--rw spd-mark
                        | espencap?                            esp-encap
     |  +--rw mark?   uint32 sport?                               inet:port-number
     |  +--rw dport?                               inet:port-number
     |  +--rw mask?   yang:hex-string oaddr*                               inet:ip-address
     |  +--rw spd-lifetime-hard spd
     |  |  +--rw added?     uint64 spd-entry* [spd-entry-id]
     |  |     +--rw used? spd-entry-id            uint64
     |  |     +--rw bytes? priority?               uint32
     |  |     +--rw packets?   uint32
                        | anti-replay-window?     uint16
     |  +--rw action?    lifetime-action  |     +--rw spd-lifetime-soft
                        | names* [name]
     |  +--rw added?     uint64  |     |  +--rw used?      uint64
                        | name-type?   ipsec-spd-name
     |  +--rw bytes?     uint32  |     |  +--rw packets?   uint32 name         string
     |  |     +--rw action?    lifetime-action
                        |     +--ro spd-lifetime-current
                        |        +--ro added?     uint64 condition
     |        +--ro used?      uint64  |        +--ro bytes?     uint32     |        +--ro packets?   uint32

6.2.  Security Association Database (SAD) Model

   The definition of this model has been extracted from the
   specification in section 4.4.2 in [RFC4301]  +--rw sad traffic-selector-list* [ts-number]
     |  +--rw sad-entry* [spi]  |     +--rw spi                         ipsec-spi     |     +--rw seq-number?                 uint64 ts-number               uint32
     |     +--rw seq-number-overflow-flag?   boolean  |     +--rw anti-replay-window?         uint16     |     +--rw rule-number?                uint32 direction?              ipsec-traffic-direction
     |     +--rw local-addresses* [start end]  |     |     +--rw start    inet:ip-address local-subnet?           inet:ip-prefix
     |  |  +--rw end      inet:ip-address     |     +--rw remote-addresses* [start end]
                        | remote-subnet?          inet:ip-prefix
     |  +--rw start    inet:ip-address  |     |     +--rw end      inet:ip-address upper-layer-protocol*   ipsec-upper-layer-proto
     |  |     +--rw next-layer-protocol*        ipsec-next-layer-proto     |     +--rw local-ports* [start end]
     |  |     |     |  +--rw start    inet:port-number
     |  |     |     |  +--rw end      inet:port-number
     |  |     |     +--rw remote-ports* [start end]
     |  |     |        +--rw start    inet:port-number
     |  |     |        +--rw end      inet:port-number
     |     +--rw security-protocol?          ipsec-protocol
                        |     +--rw ah-sa
                        |  |     +--rw integrity
                        | processing-info
     |     +--rw integrity-algorithm?   integrity-algorithm-t  |     |  +--rw key?                   string action          ipsec-spd-operation
     |     +--rw esp-sa  |     |  +--rw encryption ipsec-sa-cfg
     |  |     |     +--rw encryption-algorithm?   encryption-algorithm-t pfp-flag?            boolean
     |  |     |     +--rw key?                    string extSeqNum?           boolean
     |  |     |     +--rw iv?                     string seqOverflow?         boolean
     |  |     |     +--rw integrity statefulfragCheck?   boolean
     |  |     |     +--rw integrity-algorithm?   integrity-algorithm-t security-protocol?   ipsec-protocol
     |  |     |     +--rw key?                   string mode?                ipsec-mode
     |  |  +--rw combined-enc-intr?   boolean     |     +--rw sad-lifetime-hard ah-algorithms
     |  |  +--rw added?     uint64     |     |  +--rw used?      uint64 ah-algorithm*   integrity-algorithm-t
     |  |  +--rw bytes?     uint32     |     |  +--rw packets? trunc-length?   uint32
     |  |  +--rw action?    lifetime-action     |     +--rw sad-lifetime-soft esp-algorithms
     |  |  +--rw added?     uint64     |     |  +--rw used?      uint64 authentication*   integrity-algorithm-t
     |  |  +--rw bytes?     uint32     |     |  +--rw packets?   uint32 encryption*       encryption-algorithm-t
     |  |  +--rw action?    lifetime-action     |     +--rw mode?                       ipsec-mode     |  +--rw statefulfragCheck?          boolean tfc_pad?          uint32
     |     +--rw dscp?                       yang:hex-string  |     +--rw path-mtu?                   uint16     |     +--rw tunnel
     |  |     |        +--rw local?          inet:ip-address
     |  |     |        +--rw remote?         inet:ip-address
     |  |     |        +--rw bypass-df?      boolean
     |  |     |        +--rw bypass-dscp?    boolean
     |  |     |        +--rw dscp-mapping?   yang:hex-string
     |  |     |        +--rw ecn?            boolean
     |  |     +--rw encap spd-lifetime-soft
     |  |     |  +--rw espencap?   esp-encap time?      yang:timestamp
     |  |     |  +--rw sport?      inet:port-number idle?      yang:timestamp
     |  |     |  +--rw dport?      inet:port-number
                        |     |  +--rw oaddr?      inet:ip-address
                        |     +--ro sad-lifetime-current
                        |     |  +--ro added?     uint64
                        |     |  +--ro used?      uint64
                        |     |  +--ro bytes?     uint32
     |  |  +--ro     |  +--rw packets?   uint32
     |     +--ro state?                      sa-state
                        |     +--ro stats
                        |     |  +--ro replay-window?   uint32  |     |  +--ro replay?          uint32  +--rw action?    lifetime-action
     |  |  +--ro failed?          uint32     +--rw spd-lifetime-hard
     |     +--ro replay_state  |     |  +--ro seq?      uint32  +--rw time?      yang:timestamp
     |  |  +--ro oseq?     uint32     |  +--rw idle?      yang:timestamp
     |  +--ro bitmap?   uint32  |     +--ro replay_state_esn     |        +--ro bmp-len?  +--rw bytes?     uint32
     |        +--ro oseq?            uint32  |        +--ro oseq-hi?         uint32     |        +--ro seq-hi?  +--rw packets?   uint32
     |        +--ro replay-window?   uint32  |     +--ro bmp*             uint32

       rpcs:
       +---x sadb_register
           +---w input
           |  +---w base-list* [version]
           |     +---w version       string
           |     +---w msg_type?     sadb-msg-type spd-lifetime-current
     |     +---w msg_satype?   sadb-msg-satype  |     +---w msg_seq?      uint32
           +--ro output        +--ro base-list* [version] time?      yang:timestamp
     |  +--ro version       string  |        +--ro msg_type?     sadb-msg-type idle?      yang:timestamp
     |  +--ro msg_satype?   sadb-msg-satype  |        +--ro msg_seq? bytes?     uint32
              +--ro algorithm-supported*
                 +--ro authentication
                 |  +--ro name?       integrity-algorithm-t
                 |  +--ro ivlen?      uint8
                 |  +--ro min-bits?   uint16
                 |  +--ro max-bits?   uint16
                 +--ro encryption
                    +--ro name?       encryption-algorithm-t
                    +--ro ivlen?      uint8
                    +--ro min-bits?   uint16
                    +--ro max-bits?   uint16

       notifications:
       +---n spdb_expire
       |  +--ro index?   uint64
       +---n sadb_acquire
       |  +--ro base-list* [version]
       |     +--ro version       string
       |     +--ro msg_type?     sadb-msg-type
     |     +--ro msg_satype?   sadb-msg-satype  |        +--ro msg_seq? packets?   uint32
       +---n sadb_expire
       |  +--ro base-list* [version]
       |
     |  +--ro version       string
       | ike-sa-state
     |     +--ro msg_type?     sadb-msg-type uptime
     |     |  +--ro msg_satype?   sadb-msg-satype running?   yang:date-and-time
     |     |  +--ro msg_seq?      uint32 since?     yang:date-and-time
     |     +--ro spi?                        ipsec-spi initiator?             boolean
     |     +--ro anti-replay-window?         uint16 initiator-ikesa-spi?   uint64
     |     +--ro state?                      sa-state responder-ikesa-spi?   uint64
     |     +--ro encryption-algorithm?       encryption-algorithm-t nat-local?             boolean
     |     +--ro authentication-algorithm?   integrity-algorithm-t nat-remote?            boolean
     |     +--ro sad-lifetime-hard
       | nat-any?               boolean
     |     +--ro added?     uint64
       | espencap?              esp-encap
     |     +--ro used?      uint64
       | sport?                 inet:port-number
     |     +--ro bytes?     uint32
       | dport?                 inet:port-number
     |     +--ro packets?   uint32 oaddr*                 inet:ip-address
     |     +--ro sad-lifetime-soft
       | established?           uint64
     |     +--ro added? rekey-time?            uint64
     |  |     +--ro used? reauth-time?           uint64
     |  |     +--ro bytes?     uint32
       | child-sas* []
     |        +--ro packets?   uint32 spis
     |           +--ro sad-lifetime-current spi-in?    ic:ipsec-spi
     |           +--ro added?     uint64
       | spi-out?   ic:ipsec-spi
     +--ro used?      uint64
       | number-ike-sas
        +--ro bytes? total?               uint32
       |
        +--ro packets? half-open?           uint32
       +---n sadb_bad-spi
        +--ro state    ipsec-spi

6.3.  Peer Authorization Database (PAD) Model half-open-cookies?   uint32

6.2.  IKE-less case model

   The definition of this the SPD model has been mainly extracted from the
   specification in section 4.4.3 4.4.1 and Appendix D in [RFC4301].  Unlike
   existing implementations (e.g.  XFRM), it is worth mentioning that
   this model follows [RFC4301] (NOTE: We have observed and, consequently, each policy (spd-
   entry) consists of one or more traffic selectors.

   The definition of the SAD model has been extracted from the
   specification in section 4.4.2 in [RFC4301].  Note that many implementations integrate PAD configuration as part this model
   not only associates an IPsec SA with its corresponding policy (spd-
   entry-id) but also indicates the specific traffic selector that
   caused its establishment.  In other words, each traffic selector of a
   policy (spd-entry) generates a different IPsec SA (sad-entry).

   The notifications model has been defined using as reference the
   IKEv2 configuration.)
                   +--rw pad {case1}?
                       +--rw pad-entries* [pad-entry-id]
   PF_KEYv2 standard in [RFC2367].

  module: ietf-ipsec-ikeless
    +--rw pad-entry-id             uint64 ietf-ipsec
       +--rw (identity)?
                       |  +--:(ipv4-address)
                       | spd
       |  +--rw ipv4-address?            inet:ipv4-address
                       |  +--:(ipv6-address)
                       | spd-entry* [spd-entry-id]
       |     +--rw ipv6-address?            inet:ipv6-address
                       |  +--:(fqdn-string)
                       | spd-entry-id            uint64
       |     +--rw fqdn-string?             inet:domain-name
                       |  +--:(rfc822-address-string)
                       | priority?               uint32
       |     +--rw rfc822-address-string?   string anti-replay-window?     uint16
       |  +--:(dnX509)     +--rw names* [name]
       |     |  +--rw dnX509?                  string name-type?   ipsec-spd-name
       |  +--:(id_key)     |  +--rw id_key? name         string
                       +--rw pad-auth-protocol?       auth-protocol-type
                       +--rw auth-method
                           +--rw auth-m?          auth-method-type
                           +--rw pre-shared
       |     +--rw secret?   string
                           +--rw rsa-signature
                              +--rw key-data?    string
                              +--rw key-file?    string
                              +--rw ca-data*     string
                              +--rw ca-file?     string
                              +--rw cert-data?   string
                              +--rw cert-file?   string
                              +--rw crl-data?    string
                              +--rw crl-file?    string

6.4.  Internet Key Exchange (IKEv2) Model

   The model related to IKEv2 has been extracted from reading IKEv2
   standard in [RFC7296], and observing some open source
   implementations, such as Strongswan or Libreswan.

                        +--rw ikev2 {case1}? condition
       |     |  +--rw ike-connection traffic-selector-list* [ts-number]
       |     |     +--rw ike-conn-entries* [conn-name] ts-number               uint32
       |     |     +--rw conn-name            string direction?              ipsec-traffic-direction
       |     |     +--rw autostartup          type-autostartup local-subnet?           inet:ip-prefix
       |     |     +--rw nat-traversal?       boolean remote-subnet?          inet:ip-prefix
       |     |     +--rw initial-contact?     boolean upper-layer-protocol*   ipsec-upper-layer-proto
       |     |     +--rw encap local-ports* [start end]
       |     |     |  +--rw espencap?   esp-encap start    inet:port-number
       |     |     |  +--rw sport? end      inet:port-number
       |     |     +--rw remote-ports* [start end]
       |     |        +--rw dport? start    inet:port-number
       |     |        +--rw end      inet:port-number
       |     +--rw oaddr?      inet:ip-address processing-info
       |     |  +--rw version?             enumeration action          ipsec-spd-operation
       |     |  +--rw phase1-lifetime      uint32 ipsec-sa-cfg
       |     |     +--rw phase1-authalg*      integrity-algorithm-t pfp-flag?            boolean
       |     |     +--rw phase1-encalg*       encryption-algorithm-t extSeqNum?           boolean
       |     |     +--rw combined-enc-intr? seqOverflow?         boolean
       |     |     +--rw dh_group             uint32 statefulfragCheck?   boolean
       |     |     +--rw local
                        | security-protocol?   ipsec-protocol
       |     |     +--rw (my-identifier-type)?
                        |  |     |  |  +--:(ipv4)
                        |  |     | mode?                ipsec-mode
       |     |     +--rw ipv4?            inet:ipv4-address
                        |  |     |  |  +--:(ipv6)
                        |  | ah-algorithms
       |     |     |  +--rw ipv6?            inet:ipv6-address
                        |  |     |  |  +--:(fqdn)
                        |  | ah-algorithm*   integrity-algorithm-t
       |     |     |  +--rw fqdn?            inet:domain-name
                        |  |     |  |  +--:(dn)
                        |  |     | trunc-length?   uint32
       |     |     +--rw dn?              string
                        |  | esp-algorithms
       |     |  +--:(user_fqdn)     |  +--rw authentication*   integrity-algorithm-t
       |     |     |  +--rw user_fqdn?       string encryption*       encryption-algorithm-t
       |     |     |  +--rw my-identifier    string tfc_pad?          uint32
       |     |     +--rw remote
                        | tunnel
       |     |        +--rw (my-identifier-type)?
                        |  |     |  |  +--:(ipv4)
                        | local?          inet:ip-address
       |     |        +--rw remote?         inet:ip-address
       |     |        +--rw ipv4?            inet:ipv4-address bypass-df?      boolean
       |     |        +--rw bypass-dscp?    boolean
       |     |  +--:(ipv6)        +--rw dscp-mapping?   yang:hex-string
       |     |        +--rw ecn?            boolean
       |     +--rw spd-lifetime-soft
       |     |  +--rw ipv6?            inet:ipv6-address
                        | time?      yang:timestamp
       |     |  +--rw idle?      yang:timestamp
       |  +--:(fqdn)     |  +--rw bytes?     uint32
       |     |  +--rw packets?   uint32
       |     |  +--rw fqdn?            inet:domain-name action?    lifetime-action
       |     +--rw spd-lifetime-hard
       |     |  +--rw time?      yang:timestamp
       |  +--:(dn)     |  +--rw idle?      yang:timestamp
       |     |  +--rw bytes?     uint32
       |     |  +--rw dn?              string
                        | packets?   uint32
       |     +--ro spd-lifetime-current
       |        +--ro time?      yang:timestamp
       |  +--:(user_fqdn)        +--ro idle?      yang:timestamp
       |        +--ro bytes?     uint32
       |        +--ro packets?   uint32
       +--rw sad
          +--rw sad-entry* [sad-entry-id]
             +--rw sad-entry-id                uint64
             +--rw spi?                        ic:ipsec-spi
             +--rw seq-number?                 uint64
             +--rw seq-number-overflow-flag?   boolean
             +--rw anti-replay-window?         uint16
             +--rw spd-entry-id?               uint64
             +--rw local-subnet?               inet:ip-prefix
             +--rw remote-subnet?              inet:ip-prefix
             +--rw upper-layer-protocol*       ipsec-upper-layer-proto
             +--rw local-ports* [start end]
             |  +--rw start    inet:port-number
             |  +--rw user_fqdn?       string end      inet:port-number
             +--rw remote-ports* [start end]
             |  +--rw start    inet:port-number
             |  +--rw end      inet:port-number
             +--rw security-protocol?          ic:ipsec-protocol
             +--rw sad-lifetime-hard
             |  +--rw my-identifier    string time?      yang:timestamp
             |  +--rw idle?      yang:timestamp
             |  +--rw pfs_group* bytes?     uint32
             |  |  +--rw ipsec-sad-lifetime-hard
                        |  |     | packets?   uint32
             +--rw added?     uint64
                        |  | sad-lifetime-soft
             |  +--rw used?      uint64
                        | time?      yang:timestamp
             |  +--rw idle?      yang:timestamp
             |  +--rw bytes?     uint32
             |  |     |  +--rw packets?   uint32
             |  |     |  +--rw action?    lifetime-action
                        |  |    ic:lifetime-action
             +--rw mode?                       ic:ipsec-mode
             +--rw statefulfragCheck?          boolean
             +--rw dscp?                       yang:hex-string
             +--rw path-mtu?                   uint16
             +--rw ipsec-sad-lifetime-soft tunnel
             |  +--rw local?          inet:ip-address
             |  +--rw remote?         inet:ip-address
             |  +--rw added?     uint64 bypass-df?      boolean
             |  +--rw bypass-dscp?    boolean
             |  +--rw dscp-mapping?   yang:hex-string
             |  +--rw used?      uint64 ecn?            boolean
             +--rw espencap?                   esp-encap
             +--rw sport?                      inet:port-number
             +--rw dport?                      inet:port-number
             +--rw oaddr*                      inet:ip-address
             +--ro sad-lifetime-current
             |  +--ro time?      yang:timestamp
             |  +--ro idle?      yang:timestamp
             |  +--rw  +--ro bytes?     uint32
             |  |     |  +--rw  +--ro packets?   uint32
                        |  |     |  +--rw action?    lifetime-action
                        |  |
             +--ro ike-stats
                        | stats
             |  +--ro uptime replay-window?   uint32
             |  +--ro replay?          uint32
             |  +--ro failed?          uint32
             +--ro replay_state
             |  +--ro running?   yang:date-and-time seq?      uint32
             |  +--ro oseq?     uint32
             |  +--ro bitmap?   uint32
             +--ro replay_state_esn
             |  +--ro since?     yang:date-and-time bmp-len?         uint32
             |  +--ro oseq?            uint32
             |  +--ro initiator?       boolean oseq-hi?         uint32
             |  +--ro seq-hi?          uint32
             |  +--ro initiator-spi?   uint64 replay-window?   uint32
             |  +--ro bmp*             uint32
             +--rw ah-sa
             |  +--rw integrity
             |     +--rw integrity-algorithm?   ic:integrity-algorithm-t
             |     +--rw key?                   string
             +--rw esp-sa
                +--rw encryption
                |  +--rw encryption-algorithm?   ic:encryption-algorithm-t
                |  +--rw key?                    yang:hex-string
                |  +--rw iv?                     yang:hex-string
                +--rw integrity
                |  +--rw integrity-algorithm?   ic:integrity-algorithm-t
                |  +--rw key?                   yang:hex-string
                +--rw combined-enc-intr?   boolean

    notifications:
      +---n spdb_expire
      |  +--ro responder-spi? index?   uint64
      +---n sadb_acquire
      |  +--ro base-list* [version]
      |  |  +--ro nat-local?       boolean version       string
      |  |  +--ro nat-remote?      boolean msg_type?     sadb-msg-type
      |  |  +--ro nat-any?         boolean msg_satype?   sadb-msg-satype
      |  |  +--ro established?     uint64 msg_seq?      uint32
      |  +--ro local-subnet?           inet:ip-prefix
      |  +--ro rekey-time?      uint64 remote-subnet?          inet:ip-prefix
      |  +--ro upper-layer-protocol*   ipsec-upper-layer-proto
      |  +--ro reauth-time?     uint64 local-ports* [start end]
      |  |  +--ro child-sas* start    inet:port-number
      |  |  +--ro spis end      inet:port-number
      |  +--ro remote-ports* [start end]
      |     +--ro spi-in?    ipsec-spi start    inet:port-number
      |     +--ro end      inet:port-number
      +---n sadb_expire
      |  +--ro spi-out?   ipsec-spi base-list* [version]
      |  |  +--ro number-ike-sas version       string
      |  |  +--ro total? msg_type?     sadb-msg-type
      |  |  +--ro msg_satype?   sadb-msg-satype
      |  |  +--ro msg_seq?      uint32
      |  +--ro half-open? spi?                        ic:ipsec-spi
      |  +--ro anti-replay-window?         uint16
      |  +--ro encryption-algorithm?       ic:encryption-algorithm-t
      |  +--ro authentication-algorithm?   ic:integrity-algorithm-t
      |  +--ro sad-lifetime-hard
      |  |  +--ro time?      yang:timestamp
      |  |  +--ro idle?      yang:timestamp
      |  |  +--ro bytes?     uint32
      |  |  +--ro packets?   uint32
      |  +--ro sad-lifetime-soft
      |  |  +--ro time?      yang:timestamp
      |  |  +--ro idle?      yang:timestamp
      |  |  +--ro bytes?     uint32
      |  |  +--ro packets?   uint32
      |  +--ro sad-lifetime-current
      |     +--ro time?      yang:timestamp
      |     +--ro idle?      yang:timestamp
      |     +--ro bytes?     uint32
      |     +--ro packets?   uint32
      +---n sadb_bad-spi
         +--ro state    ic:ipsec-spi

7.  Use cases examples

   This section explains how different traditional configurations, that
   is, host-to-host and gateway-to-gateway are deployed using this SDN-
   based IPsec management service.  In turn, these configurations will
   be typical in modern networks where, for example, virtualization will
   be key.

7.1.  Host-to-Host  Host-to-host or Gateway-to-gateway gateway-to-gateway under the same controller

                      +----------------------------------------+
                      |           Security Controller          |
                      |                                        |
                   (1)|   +--------------+ (2)+--------------+ |
      Flow-based  ------> |Translate into|--->| South. Prot. | |
      Security. Pol.  |   |IPsec Policies|    |              | |
                      |   +--------------+    +--------------+ |
                      |                          |     |       |
                      |                          |     |       |
                      +--------------------------|-----|-------+
                                                 |     |
                                                 | (3) |
                       |-------------------------+     +---|
                       V                                   V
           +----------------------+         +----------------------+
           |    NSF1              |<=======>|   NSF2               |
           |IKEv2/IPsec(SPD/PAD)  |         |IKEv2/IPsec(SPD/PAD)  |
           +----------------------+  (4)    +----------------------+

    Figure 3: Host-to-Host Host-to-host / Gateway-to-Gateway gateway-to-gateway single controller flow
                             for case 1 . the IKE case.

   Figure 3 describes the case 1: IKE case:

   1.  The administrator defines general flow-based security policies.
       The Security Controller looks for the NSFs involved (NSF1 and
       NSF2).

   2.  The Security Controller generates IKEv2 credentials for them and
       translates the policies into SPD and PAD entries.

   3.  The Security Controller inserts the SPD and PAD entries in both
       NSF1 and NSF2.

   4.  The flow is protected with the IPsec SA established with IKEv2.

                        +----------------------------------------+
                        |    (1)     Security Controller         |
            Flow-based  |                                        |
            Security -----------|                                |
            Policy      |       V                                |
                        |  +---------------+ (2)+-------------+  |
                        |  |Translate into |--->| South. Prot.|  |
                        |  |IPsec policies |    |             |  |
                        |  +---------------+    +-------------+  |
                        |                         |     |        |
                        |                         |     |        |
                        +-------------------------| --- |--------+
                                                  |     |
                                                  | (3) |
                           |----------------------+     +--|
                           V                               V
                  +------------------+       +------------------+
                  |    NSF1          |<=====>|   NSF2           |
                  |IPsec(SPD/SAD)    |   4)  |IPsec(SPD/SAD)    |
                  +------------------+       +------------------+

    Figure 4: Host-to-Host Host-to-host / Gateway-to-Gateway gateway-to-gateway single controller flow
                            for case 2. IKE-less case.

   In case 2, IKE-less case, flow-based security policies defined by the
   administrator are also translated into IPsec SPD entries and inserted into
   the corresponding NSFs.  Besides, fresh SAD entries will be also
   generated by the Security Controller and enforced in the NSFs.  In
   this case case, the controller does not run any IKE IKEv2 implementation, and
   it provides the cryptographic material for the IPsec SAs.  These keys
   will be also distributed securely through the southbound interface.
   Note that this is possible because both NSFs are managed by the same
   controller.

   Figure 4 describes the case 2, IKE-less, when a data packet needs to be
   protected in the path between the NSF1 and NSF2:

   1.  The administrator establishes the flow-based security policies.
       The Security Controller looks for the involved NSFs.

   2.  The Security Controller translates the flow-based security
       policies into IPsec SPD and SAD entries.

   3.  The Security Controller inserts the these entries in both NSF1
       and NSF2 IPsec databases.

   4.  The flow is protected with the IPsec  It associates a lifetime to the IPsec
       SAs.  When this lifetime expires, the NSF will send a sadb_expire
       notification to the Security Controller in order to start the
       rekeying process.

   4.  The flow is protected with the IPsec SA established by the
       Security Controller.

   Both NSFs could be two hosts that exchange traffic and require to
   establish an end-to-end security association to protect their
   communications (host-to-host) or two gateways (gateway-to-gateway)), (gateway-to-gateway),
   for example, within an enterprise that needs to protect the traffic
   between, for example, the networks of two branch offices.

   Applicability of these configurations appear in current and new
   networking scenarios.  For example, SD-WAN technologies are providing
   dynamic and on-demand VPN connections between branch offices offices, or
   between branches and SaaS cloud services.  Beside, IaaS services
   providing virtualization environments are deployments solutions based
   on IPsec to provide secure channels between virtual instances (Host-
   to-Host) (host-
   to-host) and providing VPN solutions for virtualized networks
   (Gateway-to-Gateway).
   (gateway-to-gateway).

   In general (for case 1 IKE and case 2), IKE-less case), this system presents has various
   advantages:

   1.  It allows to create IPsec SAs among two NSFs, with only the
       application of more general flow-based security policies at the
       application layer.  Thus, administrators can manage all security
       associations in a centralized point with an abstracted view of
       the network; network.

   2.  All NSFs deployed after the application of the new policies are
       NOT manually configured, therefore allowing its deployment in an
       automated manner.

7.2.  Host-to-Host  Host-to-host or Gateway-to-gateway gateway-to-gateway under different Security security
      controllers

   It is also possible that two NSFs (i.e.  NSF1 and NSF2) are under the
   control of two different Security Controllers.  This may happen, for
   example, when two organizations, namely Enterprise A and Enterprise
   B, have their headquarters interconnected through a WAN connection
   and they both have deployed a SDN-based architecture to provide
   connectivity to all their clients.

                +-------------+                 +-------------+
                |             |                 |             |
      Flow-based|   Security  |<===============>|   Security <--Flow-based
      Sec. Pol.--> Controller |        (3)      |  Controller | Sec. Pol.
            (1) |      A      |                 |      B      |   (2)
                +-------------+                 +-------------+
                     |                                 |
                     | (4)                         (4) |
                     V                                 V
          +----------------------+          +----------------------+
          |    NSF1              |<========>|   NSF2               |
          |IKEv2/IPsec(SPD/PAD)  |          |IKEv2/IPsec(SPD/PAD)  |
          +----------------------+  (5)     +----------------------+

           Figure 5: Different Security Controllers security controllers in Case 1 IKE case

   Figure 5 describes IKE case 1 when two Security Controllers security controllers are
   involved in the process.

   1.  The A's administrator establishes general Flow-based Security
       Policies in Security Controller A.

   2.  The B's administrator establishes general Flow-based Security
       Policies in Security Controller B.

   3.  The Security Controller A realizes that protection is required
       between the NSF1 and NSF2, but the NSF2 is under the control of
       another Security Controller (Security Controller B), so it starts
       negotiations with the other controller to agree on the IPsec SPD
       policies and IKEv2 credentials for their respective NSFs.  NOTE:
       This may require extensions in the East/West interface.

   4.  Then, both Security Controllers enforce the IKEv2 credentials and
       related parameters and the SPD and PAD entries in their
       respective NSFs.

   5.  The flow is protected with the IPsec SAs established with IKEv2
       between both NSFs.

                +--------------+                   +--------------+
                |              |                   |              |
         Flow-based. --->                          |          <--- Flow-based
         Prot.  |   Security   |<=================>|   Security   |Sec.
         Pol.(1)|  Controller  |        (3)        |  Controller  |Pol. (2)
                |       A      |                   |       B      |
                +--------------+                   +--------------+
                        |                               |
                        | (4)                       (4) |
                        V                               V
                +------------------+      (5)       +------------------+
                |    NSF1          |<==============>|    NSF2          |
                |IPsec(SPD/SAD)    |                | IPsec(SPD/SAD)   |
                +------------------+                +------------------+

         Figure 6: Different Security Controllers security controllers in IKE-less case 2

   Figure 5 describes IKE-less case 2 when two Security Controllers security controllers are
   involved in the process.

   1.  The A's administrator establishes general Flow Protection
       Policies in Security Controller A.

   2.  The B's administrator establishes general Flow Protection
       Policies in Security Controller B.

   3.  The Security Controller A realizes that the flow between NSF1 and
       NSF2 MUST be protected.  Nevertheless, the controller notices
       that NSF2 is under the control of another Security Controller, so
       it starts negotiations with the other controller to agree on the
       IPsec SPD and SAD entries that define the IPsec SAs.  NOTE: It
       would worth evaluating IKEv2 as the protocol for the East/West
       interface in this case.

   4.  Once the Security Controllers have agreed on key material and the
       details of the IPsec SAs, they both enforce this information into
       their respective NSFs.

   5.  The flow is protected with the IPsec SAs established by both
       Security Controllers in their respective NSFs.

8.  Implementation notes

   At the time  Security Considerations

   First of writing all, this document, we have implemented a proof-of-
   concept using NETCONF as southbound protocol, and the YANG model
   described in Appendix A.  The netopeer implementation [netopeer] has
   been used for both case 1 and case 2 using host-to-host and gateway-
   to-gateway configuration.  For the case 1, we have used Strongswan
   [strongswan] distribution for the IKE implementation.

   Note that the proposed YANG model provides document shares all the models for SPD, SAD,
   PAD and IKE, but, as describe before, only part security issues of them SDN
   that are required
   depending of the case (1 or 2) been applied.  The Security Controller
   should be able to know the kind of case to be applied specified in the NSF "Security Considerations" section of
   [ITU-T.Y.3300] and
   to select the corresponding models based on [RFC8192].  On the YANG features defines
   for each one.

   Internally one hand, it is important to
   note that there MUST exit a security association between the NSF, the NETCONF server (that implements Security
   Controller and the I2NSF
   Agent) is able NSFs to apply protect of the required critical information
   (cryptographic keys, configuration updating the
   corresponding parameter, etc...) exchanged
   between these entities.  For example, if NETCONF datastores (running, startup, etc.).  Besides,
   it can deal with is used as
   southbound protocol between the SPD and SAD configuration at kernel level,
   through different APIs.  For example, the IETF RFC 2367 (PF_KEYv2)
   [RFC2367] provides a generic key management API that can be used not
   only for IPsec but also for other network security services to manage
   the IPsec SAD.  Besides, as an extension to this API, the document
   [I-D.pfkey-spd] specifies some PF_KEY extensions to maintain the SPD.
   This API is accessed using sockets.

   An alternative key management API based on Netlink socket API
   [RFC3549] is used to configure IPsec on the Linux Operating System.

   To allow the NETCONF server implementation interacts with the IKE
   daemon, we have used the Versatile IKE Configuration Interface (VICI)
   in Strongswan.  This allows changes in the IKE part of the
   configuration data to be applied in the IKE daemon dynamically.

9.  Security Considerations

   First of all, this document shares all the security issues of SDN
   that are specified in the "Security Considerations" section of
   [ITU-T.Y.3300] and [RFC8192].  On the one hand, it is important to
   note that there must exit a security association between the Security
   Controller and the NSFs to protect of the critical information
   (cryptographic keys, configuration parameter, etc...) exchanged
   between these entities.  For example, if NETCONF is used as
   southbound protocol between the Security Controller Security Controller and the NSFs, it
   is defined that TLS or SSH security assocation must association MUST be established
   between both entities.  On the other hand, we have divided this
   section in two parts to analyze different security considerations for
   both cases: NSF with IKEv2 (case 1) (IKE case) and NSF without IKEv2 (case 2). (IKE-less
   case).  In general, the Security Controller, as typically in the SDN
   paradigm, is a target for different type of attacks.  As a
   consequence, the Security Controller is a key entity in the
   infrastructure and MUST be protected accordingly.  In particular,
   according to this document, the Security Controller will handle
   cryptographic material so that the attacker may try to access this
   information.  Although, we can assume this attack will not likely to
   happen due to the assumed security measurements to protect the
   Security Controller, it deserves some analysis in the hypothetical
   the attack occurs.  The impact is different depending on the IKE case 1
   or IKE-less case.

8.1.  IKE case 2.

9.1.  Case 1

   In this case 1, IKE case, the Security Controller sends IKE credentials (PSK,
   public/private keys, certificates, etc...) to the NSFs using the
   security association between Security Controller and NSFs.  The
   general recommendation is that the Security Controller SHOULD NEVER
   store the IKE credentials after distributing them.  Moreover the NSFs
   MUST NOT allow the reading of these values once they have been
   applied by the Security Controller (i.e. write only operations).  One
   option is return always the same value (all 0s).  If the attacker has
   access to the Security Controller during the period of time that key
   material is generated, it may access to these values.  Since these
   values are used during NSF authentication in IKEv2, it may
   impersonate the affected NSFs.  Several recommendations are
   important.  If PSK authentication is used in IKEv2, the Security
   Controller SHOULD remove the PSK immediately after generating and
   distributing it.  Moreover, the PSK MUST have a proper length (e.g.
   minimu, 128 bit length) and strength.  If raw public keys are used,
   the Security Controller SHOULD remove the associated private key
   immediately after generating and distributing them to the NSFs.  If
   certificates are used, the NSF may generate the private key and
   exports the public key for certification in to the Security Controller.

9.2.  Case 2

8.2.  IKE-less case

   In the case 2, IKE-less case, the controller sends the IPsec SA information
   to the SAD that includes the keys for integrity and encryption (when
   ESP is used).  That key material are symmetric keys to protect data
   traffic.  The general recommendation is that the Security Controller
   SHOULD NEVER stores the keys after distributing them.  Moreover  Moreover, the
   NSFs MUST NOT allow the reading of these values once they have been
   applied by the Security Controller (i.e. write only operations).
   Nevertheless, if the attacker has access to the Security Controller
   during the period of time that key material is generated, it may
   access to these values.  In other words, it may have access to the
   key material used in the distributed IPsec SAs and observe the
   traffic between peers.  In any case, some escenarios with special
   secure enviroments environments (e.g. physically isolated data centers) make this
   type of attack difficult.  Moreover, some scenarios such as IoT
   networks with constrained devices, where reducing implementation and
   computation overhead is important, can apply IKE-less case 2 as a
   tradeoff between security and low overhead at the constrained device,
   at the cost of assuming the security impact described above.

10.

9.  Acknowledgements

   Authors want to thank Paul Wouters, Sowmini Varadhan, David Carrel,
   Yoav Nir, Tero Kivinen, Paul Wouters, Graham Bartlett, Sandeep Kampati, Linda
   Dunbar, Carlos J.  Bernardos, Alejandro Perez-Mendez, Fernando
   Pereniguez-Garcia, Alejandro Abad-Carrascosa, Abad-
   Carrascosa, Ignacio Martinez and Ruben Ricart for their valuable
   comments.

11.

10.  References

11.1.

10.1.  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>.

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <https://www.rfc-editor.org/info/rfc4301>.

   [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
              IANA Considerations Section in RFCs", RFC 5226,
              DOI 10.17487/RFC5226, May 2008,
              <https://www.rfc-editor.org/info/rfc5226>.

   [RFC7296]  Kaufman, C., Hoffman, P., Nir, Y., Eronen, P., and T.
              Kivinen, "Internet Key Exchange Protocol Version 2
              (IKEv2)", STD 79, RFC 7296, DOI 10.17487/RFC7296, October
              2014, <https://www.rfc-editor.org/info/rfc7296>.

11.2.  Informative References

   [I-D.ietf-i2nsf-framework]

   [RFC8192]  Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R.,
              and J. Jeong, "Interface to Network Security Functions
              (I2NSF): Problem Statement and Use Cases", RFC 8192,
              DOI 10.17487/RFC8192, July 2017,
              <https://www.rfc-editor.org/info/rfc8192>.

   [RFC8329]  Lopez, D., Lopez, E., Dunbar, L., Strassner, J., and R.
              Kumar, "Framework for Interface to Network Security
              Functions", RFC 8329, DOI 10.17487/RFC8329, February 2018,
              <https://www.rfc-editor.org/info/rfc8329>.

10.2.  Informative References

   [I-D.carrel-ipsecme-controller-ike]
              Carrel, D. and B. Weiss, "IPsec Key Exchange using a
              Controller", draft-carrel-ipsecme-controller-ike-01 (work
              in progress), March 2019.

   [I-D.ietf-i2nsf-framework]
              Lopez, D., Lopez, E., Dunbar, L., Strassner, J., and R.
              Kumar, "Framework for Interface to Network Security
              Functions", draft-ietf-i2nsf-framework-10 (work in
              progress), November 2017.

   [I-D.ietf-i2nsf-problem-and-use-cases]
              Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R.,
              and J. Jeong, "I2NSF Problem Statement and Use cases",
              draft-ietf-i2nsf-problem-and-use-cases-16 (work in
              progress), May 2017.

   [I-D.ietf-i2nsf-terminology]
              Hares, S., Strassner, J., Lopez, D., Xia, L., and H.
              Birkholz, "Interface to Network Security Functions (I2NSF)
              Terminology", draft-ietf-i2nsf-terminology-06 draft-ietf-i2nsf-terminology-07 (work in
              progress), July January 2019.

   [I-D.ietf-opsawg-nat-yang]
              Boucadair, M., Sivakumar, S., Jacquenet, C., Vinapamula,
              S., and Q. Wu, "A YANG Module for Network Address
              Translation (NAT) and Network Prefix Translation (NPT)",
              draft-ietf-opsawg-nat-yang-17 (work in progress),
              September 2018.

   [I-D.jeong-i2nsf-sdn-security-services-05]
              Jeong, J., Kim, H., Park, J., Ahn, T., and S. Lee,
              "Software-Defined Networking Based Security Services using
              Interface to Network Security Functions", draft-jeong-
              i2nsf-sdn-security-services-05 (work in progress), July
              2016.

   [I-D.pfkey-spd]
              Sakane, S., "PF_KEY Extensions for IPsec Policy Management
              in KAME Stack", October 2002.

   [I-D.sivakumar-yang-nat]
              Sivakumar, S., Boucadair, M., and S. Vinapamula, "YANG
              Data Model for Network Address Translation (NAT)", draft-
              sivakumar-yang-nat-07 (work in progress), July 2017.

   [I-D.tran-ipsecme-yang]
              Tran, K., Wang, H., Nagaraj, V., and X. Chen, "Yang Data
              Model for Internet Protocol Security (IPsec)", draft-tran-
              ipsecme-yang-01 (work in progress), June 2015.

   [ITU-T.X.1252]
              "Baseline Identity Management Terms and Definitions",
              April 2010.

   [ITU-T.X.800]
              "Security Architecture for Open Systems Interconnection
              for CCITT Applications", March 1991.

   [ITU-T.Y.3300]
              "Recommendation ITU-T Y.3300", June 2014.

   [netconf-vpn]
              Stefan Wallin, "Tutorial: NETCONF and YANG", January 2014.

   [netopeer]
              CESNET, CESNET., "NETCONF toolset Netopeer", November
              2016.

   [ONF-OpenFlow]
              ONF, "OpenFlow Switch Specification (Version 1.4.0)",
              October 2013.

   [ONF-SDN-Architecture]
              "SDN Architecture", June 2014.

   [RFC2367]  McDonald, D., Metz, C., and B. Phan, "PF_KEY Key
              Management API, Version 2", RFC 2367,
              DOI 10.17487/RFC2367, July 1998,
              <https://www.rfc-editor.org/info/rfc2367>.

   [RFC3549]  Salim, J., Khosravi, H., Kleen, A., and A. Kuznetsov,
              "Linux Netlink as an IP Services Protocol", RFC 3549,
              DOI 10.17487/RFC3549, July 2003,
              <https://www.rfc-editor.org/info/rfc3549>.

   [RFC3948]  Huttunen, A., Swander, B., Volpe, V., DiBurro, L., and M.
              Stenberg, "UDP Encapsulation of IPsec ESP Packets",
              RFC 3948, DOI 10.17487/RFC3948, January 2005,
              <https://www.rfc-editor.org/info/rfc3948>.

   [RFC6071]  Frankel, S. and S. Krishnan, "IP Security (IPsec) and
              Internet Key Exchange (IKE) Document Roadmap", RFC 6071,
              DOI 10.17487/RFC6071, February 2011,
              <https://www.rfc-editor.org/info/rfc6071>.

   [RFC7149]  Boucadair, M. and C. Jacquenet, "Software-Defined
              Networking: A Perspective from within a Service Provider
              Environment", RFC 7149, DOI 10.17487/RFC7149, March 2014,
              <https://www.rfc-editor.org/info/rfc7149>.

   [RFC7317]  Bierman, A. and M. Bjorklund, "A YANG Data Model for
              System Management", RFC 7317, DOI 10.17487/RFC7317, August
              2014, <https://www.rfc-editor.org/info/rfc7317>.

   [RFC8192]  Hares,

   [RFC7426]  Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S., Lopez,
              Hadi Salim, J., Meyer, D., Zarny, M., Jacquenet, C., Kumar, R., and J. Jeong, "Interface to Network Security Functions
              (I2NSF): Problem Statement O. Koufopavlou, "Software-
              Defined Networking (SDN): Layers and Use Cases", Architecture
              Terminology", RFC 8192, 7426, DOI 10.17487/RFC8192, July 2017,
              <https://www.rfc-editor.org/info/rfc8192>. 10.17487/RFC7426, January
              2015, <https://www.rfc-editor.org/info/rfc7426>.

   [RFC8229]  Pauly, T., Touati, S., and R. Mantha, "TCP Encapsulation
              of IKE and IPsec Packets", RFC 8229, DOI 10.17487/RFC8229,
              August 2017, <https://www.rfc-editor.org/info/rfc8229>.

   [strongswan]
              CESNET, CESNET., "StrongSwan: the OpenSource IPsec-based
              VPN Solution", April 2017.

Appendix A.  Appendix A: Common YANG model IPsec Configuration data for IKE and IKEless cases

        <CODE BEGINS> file "ietf-ipsec@2018-10-20.yang" "ietf-ipsec-common@2019-03-11.yang"

        module ietf-ipsec { ietf-ipsec-common{
                yang-version 1.1;
                namespace "urn:ietf:params:xml:ns:yang:ietf-ipsec"; "urn:ietf:params:xml:ns:yang:ietf-ipsec-common";
                prefix "eipsec"; "ipsec-common";

                import ietf-inet-types { prefix inet; }
                import ietf-yang-types { prefix yang; }

                import ietf-crypto-types {
                        prefix ct;
                        reference "draft-ietf-netconf-crypto-types-01: Common YANG Dta Types for Cryptography";
                }

                organization "University of Murcia"; "IETF I2NSF (Interface to Network Security Functions) Working Group";

                contact
                " Rafael Marin Lopez
                Dept. Information and Communications Engineering (DIIC)
                Faculty of Computer Science-University of Murcia
                30100 Murcia - Spain
                Telf: +34868888501
                e-mail: rafa@um.es

                Gabriel Lopez Millan
                Dept. Information and Communications Engineering (DIIC)
                Faculty of Computer Science-University of Murcia
                30100 Murcia - Spain
                Tel: +34 868888504
                email: gabilm@um.es

                Fernando Pereniguez Garcia
                Department of Sciences and Informatics
                University Defense Center (CUD), Spanish Air Force Academy, MDE-UPCT
                30720 San Javier - Spain
                Tel: +34 968189946
                email: fernando.pereniguez@cud.upct.es
                ";

                description "Data "Common Data model for IPSec"; SDN-based IPSec configuration.";

                revision "2018-10-20" "2019-03-11" {
                        description "Revision";
                        reference "";
                }

   feature case1

                typedef encryption-algorithm-t {
                        type ct:encryption-algorithm-ref;
                        description "feature case 1: IKE SPD PAD"; "typedef";
                } // IKE/IPSec in the NSFs
   feature case2

                typedef integrity-algorithm-t {
                        type ct:mac-algorithm-ref;
                        description "feature case 2: SPD SAD"; } // Only IPSec in
                                "This typedef enables importing modules to easily define an
                                identityref to the NSFs 'asymmetric-key-encryption-algorithm'
                                base identity.";
                }

                typedef encryption-algorithm-t ipsec-mode {
                        type enumeration {
                                enum reserved-0 {description "reserved";}
         enum des-iv4 { description "DES IV 4";}
         enum des TRANSPORT { description "DES"; "Transport mode. No NAT support."; }
                                enum 3des TUNNEL { description "3DES"; "Tunnel mode"; }
         enum rc5 {  description "RC5";
                        }
         enum idea {
                        description "IDEA"; "Type definition of IPsec mode";
                }
         enum cast

                typedef esp-encap {  description "CAST"; }
         enum blowfish
                        type enumeration {  description "BlowFish"; }
                                enum 3idea ESPINTCP { description "3IDEA"; } "ESP in TCP encapulation.";}
                                enum des-iv32 ESPINTLS { description "DES-IV32"; } "ESP in TCP encapsulation using TLS.";}
                                enum reserved-10 ESPINUDP { description "reserved-10"; } "ESP in UDP encapsulation. RFC 3948 ";}
                                enum null NONE { description "NULL"; "NOT ESP encapsulation" ; }
         enum aes-cbc {  description "AES-CBC";
                        }
         enum aes-ctr {
                        description "AES-CTR"; "type defining types of ESP encapsulation";
                }
         enum aes-ccm-8 {  description "AES-CCM-8"; }
         enum aes-ccm-12

                grouping encap { /* This is defined by XFRM */
                        description "AES-CCM-12"; }
         enum aes-ccm-16 "Encapsulation container";
                        leaf espencap { type esp-encap; description "AES-CCM-16"; }
         enum reserved-17 { "ESP in TCP, ESP in UDP or ESP in TLS";}
                        leaf sport {type inet:port-number; description "Encapsulation source port";}
                        leaf dport {type inet:port-number; description "reserved-17"; "Encapsulation destination port"; }
         enum aes-gcm-8-icv {
                        leaf-list oaddr {type inet:ip-address; description "AES-GCM-8-ICV"; "Encapsulation Original Address ";}
                }

                typedef ipsec-protocol {
                        type enumeration {
                                enum aes-gcm-12-icv ah { description "AES-GCM-12-ICV"; "AH Protocol"; }
                                enum aes-gcm-16-icv esp { description "AES-GCM-16-ICV"; "ESP Protocol"; }
                        }
         enum null-auth-aes-gmac {
                        description "Null-Auth-AES-GMAC"; "type define of ipsec security protocol";

                }
         enum ieee-p1619-xts-aes

                typedef ipsec-spi {  description "encr-ieee-p1619-xts-aes -&gt; Reserved for IEEE P1619 XTS-AES.";}
         enum camellia-cbc
                        type uint32 {  description "CAMELLIA-CBC"; range "0..max"; }
         enum camellia-ctr {
                        description "CAMELLIA.CTR"; "SPI";
                }
         enum camellia-ccm-8-icv

                typedef lifetime-action {  description "CAMELLIA-CCM-8-ICV"; }
         enum camellia-ccm-12-icv
                        type enumeration {  description "CAMELLIA-CCM-12-ICV"; }
                                enum camellia-ccm-16-icv { description "CAMELLIA-CCM-16-ICV"; } terminate-clear {description "Terminate the IPsec SA and allow the packets through";}
                                enum aes-cbc-128 { description "AES-CBC-128"; } terminate-hold {description "Terminate the IPsec SA and drop the packets";}
                                enum aes-cbc-192 { description "AES-CBC-192"; replace  {description "Replace the IPsec SA with a new one";}
                        }
         enum aes-cbc-256 {
                        description "AES-CBC-256"; "Action when lifetime expiration";
                }
         enum blowfish-128

                /*################## SPD basic groupings ####################*/

                typedef ipsec-traffic-direction {
                        type enumeration { description "BlowFish-128"; }
                                enum blowfish-192 INBOUND { description "BlowFish-192"; "Inbound traffic"; }
                                enum blowfish-256 OUTBOUND { description "BlowFish-256"; "Outbound traffic"; }
                        }
         enum blowfish-448 {
                        description "BlowFish-448"; "IPsec traffic direction";
                }

                typedef ipsec-spd-operation {
                        type enumeration {
                                enum camellia-128 PROTECT { description "CAMELLIA-128"; "PROTECT the traffic with IPsec"; }
                                enum camellia-192 BYPASS { description "CAMELLIA-192"; "BYPASS the traffic"; }
                                enum camellia-256 DISCARD { description "CAMELLIA-256"; "DISCARD the traffic"; }
                        }
                        description "Encryption algorithms -&gt; RFC_5996"; "The operation when traffic matches IPsec security policy";
                }

                typedef integrity-algorithm-t ipsec-upper-layer-proto {
                        type enumeration {
                                enum none TCP { description "NONE"; "TCP traffic"; }
                                enum hmac-md5-96 UDP { description "HMAC-MD5-96"; "UDP traffic"; }
                                enum hmac-sha1-96 SCTP { description "HMAC-SHA1-96"; } "SCTP traffic";}
                                enum des-mac DCCP { description "DES-MAC"; }
         enum kpdk-md5 {description "KPDK-MD5"; } "DCCP traffic";}
                                enum aes-xcbc-96 ICMP { description "AES-XCBC-96"; } "ICMP traffic";}
                                enum hmac-md5-128 IPv6-ICMP { description "HMAC-MD5-128"; } "IPv6-ICMP traffic";}
                                enum hmac-sha1-160 { description "HMAC-SHA1-160"; GRE {description "GRE traffic";}
                        }
         enum aes-cmac-96 {
                        description "AES-CMAC-96"; "Next layer proto on top of IP";
                }
         enum aes-128-gmac
                typedef ipsec-spd-name { description "AES-128-GMAC"; }
         enum aes-192-gmac
                        type enumeration { description "AES-192-GMAC"; }
                                enum aes-256-gmac id_rfc_822_addr { description "AES-256-GMAC"; "Fully qualified user name string."; }
                                enum hmac-sha2-256-128 id_fqdn { description "HMAC-SHA2-256-128"; "Fully qualified DNS name."; }
                                enum hmac-sha2-384-192 id_der_asn1_dn { description "HMAC-SHA2-384-192"; "X.500 distinguished name."; }
                                enum hmac-sha2-512-256 id_key { description "HMAC-SHA2-512-256"; }
         enum hmac-sha2-256-96 { description "HMAC-SHA2-256-096"; "IKEv2 Key ID."; }
                        }
                        description "Integrity Algorithms -&gt; RFC_5996"; "IPsec SPD name type";
                }

   typedef type-autostartup {
      type enumeration {
         enum ALWAYSON

                grouping lifetime {
                        description " ";}
         enum INITIATE-ON-DEMAND {description " ";}
         enum RESPOND-ONLY {description " ";}
      } "lifetime current state data";
                        leaf time {type yang:timestamp; default 0; description "Different types of how IKEv2 starts "Time since the IPsec SAs";
   }

   typedef auth-protocol-type element is added";}
                        leaf idle {type yang:timestamp; default 0; description "Time the element is in idle state";}
                        leaf bytes { type enumeration {
         enum IKEv1 { uint32; default 0; description "Authentication protocol based on IKEv1"; }
         enum IKEv2 { "Lifetime in bytes number";}
                        leaf packets {type uint32; default 0; description "Authentication protocol based on IKEv2"; "Lifetime in packets number";}
                }
         enum KINK

                /*################## SAD and SPD common basic groupings ####################*/

                grouping port-range  {
                        description "Authentication protocol based on KINK"; }
      }
      description "Peer authentication protocols";
   }

   typedef ipsec-mode "Port range grouping";
                        leaf start { type enumeration {
         enum TRANSPORT { inet:port-number; description "Transport mode"; "Start Port Number"; }
         enum TUNNEL
                        leaf end { type inet:port-number; description "Tunnel mode"; "End Port Number"; }
         enum BEET
                }

                grouping tunnel-grouping {
                        description "Bound End-to-End Tunnel (BEET) "Tunnel mode for ESP.";}
         enum RO { grouping";
                        leaf local{ type inet:ip-address; description "Route Optimization mode for Mobile IPv6";}
         enum IN_TRIGGER {description "In trigger mode for Mobile IPv6";} "Local tunnel endpoint"; }
                        leaf remote{ type inet:ip-address; description "type define of ipsec mode"; "Remote tunnel enpoint"; }

   typedef esp-encap
                        leaf bypass-df { type enumeration {
         enum ESPINTCP { description "ESP in TCP encapulation.";}
         enum ESPINTLS { description "ESP in TCP encapsulation using TLS.";}
         enum ESPINUDP { boolean; description "ESP in UDP encapsulation. RFC 3948 ";} "Bypass DF bit"; }
                        leaf bypass-dscp { type boolean; description "type defining types of ESP encapsulation"; "Bypass DSCP"; }

   typedef ipsec-protocol
                        leaf dscp-mapping { type enumeration {
         enum ah { yang:hex-string; description "AH Protocol"; "DSCP mapping"; }
         enum esp
                        leaf ecn { type boolean; description "ESP Protocol"; "Bit ECN"; }
         enum comp /* RFC 4301 ASN1 notation. Annex C*/
                }

                grouping selector-grouping {
                        description "IP Compression";} /*Supported by XFRM*/
         enum route2 "Traffic selector grouping";

                        leaf local-subnet { description "Routing Header type 2. Mobile IPv6";} /*Supported by XFRM*/
         enum hao {description "Home Agent Option";} /*Supported by XFRM*/
      } inet:ip-prefix; description "type define of ipsec security protocol"; "Local IP address subnet"; }

   typedef ipsec-spi
                        leaf remote-subnet { type uint32 { range "0..max"; } inet:ip-prefix; description "SPI"; "Remote IP address subnet"; }

   typedef lifetime-action

                        leaf-list upper-layer-protocol { type enumeration ipsec-upper-layer-proto; description "List of Upper Layer Protocol";}

                        list local-ports {
         enum terminate {description "Terminate the IPsec SA";}
         enum replace  {description "Replace
                                key "start end";
                                uses port-range;
                                description "List of local ports. When the IPsec SA with a new one";} upper-layer-protocol is ICMP this 16 bit value respresents code and type as mentioned in RFC 4301";

                        }

                        list remote-ports {
                                key "start end";
                                uses port-range;
                                description "Action when lifetime expiration"; "List of remote ports. When the upper-layer-protocol is ICMP this 16 bit value respresents code and type as mentioned in RFC 4301";
                        }

   typedef ipsec-traffic-direction
                }

                /*################## SPD ipsec-policy-grouping ####################*/

                grouping ipsec-policy-grouping {

                        description "Holds configuration information for an IPSec SPD entry.";

                        leaf spd-entry-id { type enumeration uint64; description "SPD entry id "; }
                        leaf priority {type uint32; default 0; description "Policy priority";}
                        leaf anti-replay-window {
         enum INBOUND type uint16 { range "0 | 32..1024"; } description "Inbound traffic"; "Anti replay window size"; }
         enum OUTBOUND

                        list names {
                                key "name";
                                leaf name-type { type ipsec-spd-name; description "Outbound traffic"; "SPD name type."; }
         enum FORWARD{
                                leaf name { type string; description "Forwarded traffic"; } "Policy name"; }
                                description "IPsec traffic direction"; "List of policy names";
                        }

   typedef ipsec-spd-operation

                        container condition {
      type enumeration
                                description "SPD condition - RFC4301";
                                list traffic-selector-list {
         enum PROTECT
                                        key "ts-number";
                                        leaf ts-number { type uint32; description "PROTECT the traffic with IPsec"; "Traffic selector number"; }
         enum BYPASS
                                        leaf direction { type ipsec-traffic-direction; description "BYPASS the traffic"; "in/out"; }
         enum DISCARD {
                                        uses selector-grouping;
                                        ordered-by user;
                                        description "DISCARD the traffic"; "List of traffic selectors";
                                }
                        }
      description "The operation when traffic matches IPsec security policy";

   }

   typedef ipsec-next-layer-proto

                        container processing-info {
                                description "SPD processing - RFC4301";
                                leaf action{ type enumeration ipsec-spd-operation; mandatory true; description "Bypass or discard, container ipsec-sa-cfg is empty";}

                                container ipsec-sa-cfg {
         enum TCP
                                        when "../action = 'PROTECT'";

                                        leaf pfp-flag { type boolean; description "PROTECT the traffic "Each selector has with IPsec"; a pfp flag."; }
         enum UDP
                                        leaf extSeqNum { type boolean; description "BYPASS the traffic"; "TRUE 64 bit counter, FALSE 32 bit"; }
         enum SCTP { description "PROTECT the traffic with IPsec";}
         enum DCCP { description "PROTECT the traffic with IPsec";}
         enum ICMP
                                        leaf seqOverflow { type boolean; description "PROTECT the traffic with IPsec";}
         enum IPv6-ICMP "TRUE rekey, FALSE terminare &amp; audit"; }
                                        leaf statefulfragCheck { type boolean; description "PROTECT the traffic with IPsec";}
         enum MH {description "PROTECT the traffic with IPsec";}
         enum GRE {description "PROTECT "Indicates whether (TRUE) or not (FALSE) stateful fragment checking (RFC 4301) applies to the traffic with IPsec";} SA to be created."; }
                                        leaf security-protocol { type ipsec-protocol; description "Next layer proto on top "Security protocol of IP"; IPsec SA: Either AH or ESP."; }

   typedef ipsec-spd-name
                                        leaf mode { type enumeration ipsec-mode; description "transport/tunnel"; }

                                        container ah-algorithms {
         enum id_rfc_822_addr
                                                when "../security-protocol = 'ah'";
                                                leaf-list ah-algorithm { type integrity-algorithm-t; description "Fully qualified user name string."; "Configure Authentication Header (AH)."; }
         enum id_fqdn
                                                leaf trunc-length { type uint32; description "Fully qualified DNS name."; "Truncation value for AH algorithm"; }
         enum id_der_asn1_dn {
                                                description "X.500 distinguished name."; "AH algoritms ";
                                        }
         enum id_key

                                        container esp-algorithms {
                                                when "../security-protocol = 'esp'";
                                                description "IKEv2 Key ID."; }
      } "Configure Encapsulating Security Payload (ESP).";
                                                leaf-list authentication { type integrity-algorithm-t; description "IPsec SPD name type"; "Configure ESP authentication"; }

   typedef auth-method-type {
                                                /* Most implementations also provide XAUTH protocol, others With AEAD algorithms, the authentication node is not used are: BLISS, P12, NTLM, PIN */
      type enumeration {
         enum pre-shared
                                                leaf-list encryption { type encryption-algorithm-t; description "Select pre-shared key message as the authentication method"; "Configure ESP encryption"; }
         enum rsa-signature
                                                leaf tfc_pad { type uint32; default 0; description "Select rsa digital signature as the authentication method"; "TFC padding for ESP encryption"; }
         enum dss-signature { description "Select dss digital signature as the authentication method";
                                        }
         enum eap

                                        container tunnel {
                                                when "../mode = 'TUNNEL'";
                                                uses tunnel-grouping;
                                                description "Select EAP as the authentication method"; }
      }
      description "Peer authentication method"; "tunnel grouping container";
                                        }

   typedef sa-state {
      type enumeration {
         enum Larval { description "SA larval state";}
         enum Mature { description "SA mature state";}
         enum Dying  { description "SA dying state";}
         enum Dead   {

                                        description "SA dead state";} " IPSec SA configuration container";
                                }
        description "Security Association state";
                        }

   grouping lifetime

                        container spd-lifetime-soft {
                                description "lifetime current "SPD lifetime hard state data";
                                uses lifetime;
                                leaf added {type uint64; default 0; description "added time and date";}
      leaf used action {type uint64; default 0; lifetime-action; description "used time and date";}
      leaf bytes "Action lifetime";}
                        }

                        container spd-lifetime-hard { type uint32; default 0;
                                description "current "SPD lifetime bytes";}
      leaf packets {type uint32; default 0; description "current hard state data. The action after the lifetime packets";} is to remove the SPD entry.";
                                uses lifetime;
                        }

   /*################## PAD grouping ####################*/

   grouping auth-method-grouping

                        // State data for an IPsec SPD entry
                        container spd-lifetime-current {
                                uses lifetime;
                                config false;
                                description "Peer authentication method "SPD lifetime current state data";

      container auth-method
                        }
                } /* grouping ipsec-policy-grouping */

        }
    <CODE ENDS>

Appendix B.  Appendix B: YANG model for IKE case

        <CODE BEGINS> file "ietf-ipsec-ike@2019-03-11.yang"

        module ietf-ipsec-ike {
         description "Peer authentication method container";

         leaf auth-m
                yang-version 1.1;
                namespace "urn:ietf:params:xml:ns:yang:ietf-ipsec-ike";
                prefix "ipsec-ike";

                import ietf-inet-types { type auth-method-type; description "Type of authentication method (preshared, rsa, etc.)"; prefix inet; }

         container pre-shared {
            when "../auth-m = 'pre-shared'";
            leaf secret
                import ietf-yang-types { type string; description "Pre-shared secret value";}
            description "Shared secret value"; prefix yang; }

         container rsa-signature

                import ietf-crypto-types {
            when "../auth-m = 'rsa-signature'";
            leaf key-data { type string; description "RSA private key data - PEM";
                        prefix ct;
                        reference "draft-ietf-netconf-crypto-types-01: Common YANG Data Types for Cryptography";
                }
            leaf key-file

                import ietf-ipsec-common { type string; description "RSA private key file name ";
                        prefix ic;
                        reference "Common Data model for SDN-based IPSec configuration";
                }
            leaf-list ca-data { type string; description "List

                organization "IETF I2NSF (Interface to Network Security Functions) Working Group";

                contact
                " Rafael Marin Lopez
                Dept. Information and Communications Engineering (DIIC)
                Faculty of trusted CA certs Computer Science-University of Murcia
                30100 Murcia - PEM"; }
            leaf ca-file { type string; description "List Spain
                Telf: +34868888501
                e-mail: rafa@um.es

                Gabriel Lopez Millan
                Dept. Information and Communications Engineering (DIIC)
                Faculty of trusted CA certs file"; }
            leaf cert-data { type string; description "X.509 certificate data Computer Science-University of Murcia
                30100 Murcia - PEM4"; }
            leaf cert-file { type string; description "X.509 certificate file"; }
            leaf crl-data { type string; description "X.509 CRL certificate data in base64"; }
            leaf crl-file { type string; description " X.509 CRL certificate file"; }
            description "RSA signature container";
         }
      }
   }

   grouping identity-grouping {
      description "Identification type. It is an union identity";
      choice identity {
         description "Choice Spain
                Tel: +34 868888504
                email: gabilm@um.es

                Fernando Pereniguez Garcia
                Department of identity.";

         leaf ipv4-address { type inet:ipv4-address; description "Specifies the identity as a single four (4) octet IPv4 address. An example is, 10.10.10.10. Sciences and Informatics
                University Defense Center (CUD), Spanish Air Force Academy, MDE-UPCT
                30720 San Javier - Spain
                Tel: +34 968189946
                email: fernando.pereniguez@cud.upct.es
                "; }
         leaf ipv6-address { type inet:ipv6-address; description "Specifies the identity as a single sixteen (16) octet IPv6 address. An example is FF01::101, 2001:DB8:0:0:8:800:200C:417A ."; }
         leaf fqdn-string { type inet:domain-name; description "Specifies the identity as a Fully-Qualified Domain Name (FQDN) string. An example is: example.com. The string MUST not contain any terminators (e.g., NULL, CR, etc.)."; }
         leaf rfc822-address-string { type string; description "Specifies the identity as a fully-qualified RFC822 email address string. An example is, jsmith@example.com. The string MUST not contain any terminators (e.g., NULL, CR, etc.)."; }
         leaf dnX509 { type string; description "Specifies the identity as a distinguished name in the X.509 tradition."; }
         leaf id_key { type string; description "Key id";
         } /* From RFC4301 list of id types */
      }
   } /* grouping identity-grouping */

   /*################ end PAD grouping ##################*/

   /*################## SAD and SPD grouping ####################*/

   grouping ip-addr-range {
      description "IP address range grouping";
      leaf start { type inet:ip-address; description "Start IP address"; }
      leaf end { type inet:ip-address; description "End IP address"; }
   }

   grouping port-range  {
      description "Port range grouping";
      leaf start { type inet:port-number; description "Start IP address"; }
      leaf end { type inet:port-number; description "End IP address"; }
   }

   grouping tunnel-grouping {
      description "Tunnel mode grouping";
      leaf local{ type inet:ip-address; description "Local tunnel endpoint"; }
      leaf remote{ type inet:ip-address; description "Remote tunnel enpoint"; }
      leaf bypass-df { type boolean; description "bypass DF bit"; }
      leaf bypass-dscp { type boolean; description "bypass DSCP"; }
      leaf dscp-mapping { type yang:hex-string; description "DSCP mapping"; }
      leaf ecn { type boolean; description "Bit ECN"; } /* RFC 4301 ASN1 notation. Annex C*/
   }

   grouping selector-grouping {
   description "Traffic selector grouping";
      list local-addresses {
         key "start end";
         uses ip-addr-range;
         description "List of local addresses";
      }
      list remote-addresses {
         key "start end";
         uses ip-addr-range;
         description "List of remote addresses";
      }
      leaf-list next-layer-protocol { type ipsec-next-layer-proto; description "List of Next Layer Protocol";}
      list local-ports {
         key "start end";
         uses port-range;
         description "List of local ports";
      }
      list remote-ports {
         key "start end";
         uses port-range;
         description "List of remote ports";
      }
   }

   /*################## SAD grouping ####################*/
   grouping ipsec-sa-grouping {
      description "Configure Security Association (SA). Section 4.4.2.1 in RFC 4301";

      leaf spi { type ipsec-spi;  description "Security Parameter Index";}
      leaf seq-number { type uint64; description "Current sequence number of IPsec packet."; }
      leaf seq-number-overflow-flag { type boolean; description "The flag indicating whether overflow of the sequence number counter should prevent transmission of additional packets on the SA, or whether rollover is permitted."; }
      leaf anti-replay-window { type uint16 { range "0 | 32..1024"; } description "Anti replay window size"; }
      leaf rule-number {type uint32; description "This value links the SA with the SPD entry";}

      uses selector-grouping;

      leaf security-protocol { type ipsec-protocol; description "Security protocol of IPsec SA: Either AH or ESP."; }

      container ah-sa {
         when "../security-protocol = 'ah'";
         description "Configure Authentication Header (AH) for SA";
         container integrity {
            description "Configure integrity for IPSec Authentication Header (AH)";
            leaf integrity-algorithm { type integrity-algorithm-t; description "Configure Authentication Header (AH)."; }
            leaf key { type string; description "AH key value";}
         }
      }

      container esp-sa {
         when "../security-protocol = 'esp'";
         description "Set IPSec Encapsulation Security Payload (ESP)";

         container encryption {
            description "Configure encryption for IPSec Encapsulation Secutiry Payload (ESP)";
            leaf encryption-algorithm { type encryption-algorithm-t; description "Configure ESP encryption"; }
            leaf key { type string; description "ESP encryption key value";}
            leaf iv {type string; description "ESP encryption IV value"; }
         }

         container integrity {
            description "Configure authentication for IPSec Encapsulation Secutiry Payload (ESP)";
            leaf integrity-algorithm { type integrity-algorithm-t; description "Configure Authentication Header (AH)."; }
            leaf key { type string; description "ESP integrity key value";}
         }

         leaf combined-enc-intr { type boolean; description "ESP combined mode algorithms. The algorithm is specified in encryption-algorithm in the container encryption";}
      }

      container sad-lifetime-hard {
         description "SAD lifetime hard state data";
         uses lifetime;
         leaf action {type lifetime-action; description "action lifetime";}
      }

      container sad-lifetime-soft {
         description "SAD lifetime hard state data";
         uses lifetime;
         leaf action {type lifetime-action; description "action lifetime";}
      }

      leaf mode { type ipsec-mode; description "SA Mode"; }
      leaf statefulfragCheck { type boolean; description "TRUE stateful fragment checking, FALSE no stateful fragment checking"; }
      leaf dscp { type yang:hex-string; description "DSCP value"; }
      leaf path-mtu { type uint16; description "Maximum size of an IPsec packet that can be transmitted without fragmentation"; }

      container tunnel {
         when "../mode = 'TUNNEL'";
         uses tunnel-grouping;
         description "Container for tunnel grouping";
      }

      container encap { /* This is defined by XFRM */
         description "Encapsulation container";
         leaf espencap { type esp-encap; description "ESP in TCP, ESP in UDP or ESP in TLS";}
         leaf sport {type inet:port-number; description "Encapsulation source port";}
         leaf dport {type inet:port-number; description "Encapsulation destination port"; }
         leaf oaddr {type inet:ip-address; description "Encapsulation Original Address ";}
      }

      // STATE DATA for SA
      container sad-lifetime-current {
         uses lifetime;
         config false;
         description "SAD lifetime current state data";
      }

      leaf state {type sa-state; config false; description "current state of SA (mature, larval, dying or dead)"; }

      container stats { // xfrm.h
         leaf replay-window {type uint32; default 0; description " "; }
         leaf replay {type uint32; default 0; description "packets detected out of the replay window and dropped because they are replay packets";}
         leaf failed {type uint32; default 0; description "packets detected out of the replay window ";}
         config false;
         description "SAD statistics";
     }

      container replay_state { // xfrm.h

         leaf seq {type uint32; default 0; description "input traffic sequence number when anti-replay-window != 0";}
         leaf oseq {type uint32; default 0; description "output traffic sequence number";}
         leaf bitmap {type uint32; default 0; description "";}
         config false;
         description "Anti-replay Sequence Number state";
      }

      container replay_state_esn { // xfrm.h
         leaf bmp-len {type uint32; default 0; description "bitmap length for ESN"; }
         leaf oseq { type uint32; default 0;

                description "output traffic sequence number"; }
         leaf oseq-hi "Data model for IKE case.";

                revision "2019-03-11" { type uint32; default 0;
                        description "Revision 1.1";
                        reference "";
                }
         leaf seq-hi

                typedef type-autostartup {
                        type uint32; default 0; enumeration {
                                enum ADD {description "IPsec configuration is only loaded but not started.";}
                                enum ON-DEMAND {description "IPsec configuration is loaded and transferred to the NSF's kernel";}
                                enum START { description ""; "IPsec configuration is loaded and transferred to the NSF's kernel, and the IKEv2 based IPsec SAs are established";}
                        }
         leaf replay-window {type uint32; default 0;
                        description ""; "Different policies of when to start an IKEv2 based IPsec SA";
                }
         leaf-list bmp

                typedef auth-protocol-type {
                        type uint32; enumeration {
                                enum IKEv2 { description "bitmaps for ESN (depends "Authentication protocol based on bmp-len) "; IKEv2"; }
         config false;
         description "Anti-replay Extended Sequence Number (ESN) state";
                        }
                        description "IKE authentication protocol version";
                }

/*################## end SAD grouping ##################*/

/*################## SPD grouping ####################*/

   grouping ipsec-policy-grouping

                typedef pfs-group {
                        type enumeration {
                                enum NONE {description "NONE";}
                                enum 768-bit-MODP {description "768-bit MODP Group";}
                                enum 1024-bit-MODP {description "1024-bit MODP Group";}
                                enum 1536-bit-MODP {description "1536-bit MODP Group";}
                                enum 2048-bit-MODP {description "2048-bit MODP Group";}
                                enum 3072-bit-MODP {description "3072-bit MODP Group";}
                                enum 4096-bit-MODP {description "4096-bit MODP Group";}
                                enum 6144-bit-MODP {description "6144-bit MODP Group";}
                                enum 8192-bit-MODP {description "8192-bit MODP Group";}
                        }
                        description "Holds configuration information "PFS group for an IPSec SPD entry.";

      leaf rule-number IPsec rekey";
                }

                /*################## PAD  ####################*/

                typedef auth-method-type { type uint64; description "SPD index. RFC4301 does not mention an index however real
                        /* Most implementations also provide a policy index/or id to refer a policy. "; }
      leaf priority {type uint32; default 0; description "Policy priority";}

      list names XAUTH protocol, others used are: BLISS, P12, NTLM, PIN */
                        type enumeration {
                                enum pre-shared { description "Select pre-shared key "name";
         leaf name-type message as the authentication method"; }
                                enum eap { type ipsec-spd-name; description "SPD name type."; "Select EAP as the authentication method"; }
         leaf name
                                enum digital-signature { description "Select digital signature method";}
                                enum null {description "null authentication";}
                        }
                        description "Peer authentication method";
                }

                typedef signature-algorithm-t {
                        type string; ct:signature-algorithm-ref; // We must reference to "signature-algorithm-ref" but we temporary use hash-algorithm-ref
                        description "Policy name"; "This typedef enables referencing to any digital signature algorithm";
                }

                grouping auth-method-grouping {
                        description "List of policy names";
      } "Peer authentication method data";

                        container condition auth-method {
                                description "SPD condition -&gt; RFC4301";
         list traffic-selector-list {
            key "ts-number"; "Peer authentication method container";

                                leaf ts-number auth-m { type uint32; auth-method-type; description "Traffic selector number"; "Type of authentication method (pre-shared, eap, digital signature, null)"; }

                                container eap-method {
                                        when "../auth-m = 'eap'";
                                        leaf direction eap-type { type ipsec-traffic-direction; uint8; description "in/fwd/out"; "EAP method type"; }
            uses selector-grouping;
            leaf selector-priority {type uint32; default 0;
                                        description "It establishes a priority to the traffic selector";}
            ordered-by user; "EAP method description "List of traffic selectors";
         } used when auth method is eap";
                                }

                                container processing-info pre-shared {
         description "SPD processing -&gt; RFC4301";
                                        when "../auth-m[.='pre-shared' or .='eap']";
                                        leaf action{ secret { type ipsec-spd-operation; mandatory true; yang:hex-string; description "If the action is bypass or discard processing container ipsec-sa-cfg is empty";} "Pre-shared secret value";}
                                        description "Shared secret value";
                                }

                                container ipsec-sa-cfg digital-signature {
                                        when "../action = 'PROTECT'"; "../auth-m[.='digital-signature' or .='eap']";
                                        leaf pfp-flag { type boolean; ds-algorithm {type signature-algorithm-t; description "Each selector has with a pfp flag."; } "Name of the digital signature algorithm";}
                                        leaf extSeqNum { type boolean; raw-public-key {type yang:hex-string; description "TRUE 64 bit counter, FALSE 32 bit"; } "RSA raw public key" ;}
                                        leaf seqOverflow key-data { type boolean; string; description "TRUE rekey, FALSE terminare &amp; audit"; "RSA private key data - PEM"; }
                                        leaf statefulfragCheck key-file { type boolean; string; description "TRUE stateful fragment checking, FALSE no stateful fragment checking"; "RSA private key file name "; }
            leaf security-protocol
                                        leaf-list ca-data { type ipsec-protocol; string; description "Security protocol "List of IPsec SA: Either AH or ESP."; trusted CA certs - PEM"; }
                                        leaf mode ca-file { type ipsec-mode; string; description "transport/tunnel"; "List of trusted CA certs file"; }

            container ah-algorithms {
               when "../security-protocol = 'ah'";
               leaf-list ah-algorithm
                                        leaf cert-data { type integrity-algorithm-t; description "Configure Authentication Header (AH)."; } string; description "AH algoritms "; "X.509 certificate data - PEM4"; }

            container esp-algorithms
                                        leaf cert-file {
               when "../security-protocol = 'esp'"; type string; description "Configure Encapsulating Security Payload (ESP).";
               leaf-list authentication "X.509 certificate file"; }
                                        leaf crl-data { type integrity-algorithm-t; string; description "Configure ESP authentication"; "X.509 CRL certificate data in base64"; }
               leaf-list encryption
                                        leaf crl-file { type encryption-algorithm-t; string; description "Configure ESP encryption"; } " X.509 CRL certificate file"; }

            container tunnel
                                        leaf oscp-uri {
               when "../mode = 'TUNNEL'";
               uses tunnel-grouping; type inet:uri; description "tunnel grouping container";
            } "OCSP URI";}
                                        description " IPSec SA configuration "RSA signature container";
                                }
                        }

      container spd-mark
                }

                grouping identity-grouping {
                        description "Identification type. It is an union identity";
                        choice identity {
                                description "Choice of identity.";
                                leaf ipv4-address { type inet:ipv4-address; description "policy: mark MARK  mask MASK "Specifies the identity as a single four (4) octet IPv4 address. An example is, 10.10.10.10. "; }
                                leaf mark ipv6-address { type uint32; default 0; inet:ipv6-address; description "mark value";} "Specifies the identity as a single sixteen (16) octet IPv6 address. An example is FF01::101, 2001:DB8:0:0:8:800:200C:417A ."; }
                                leaf mask fqdn-string { type yang:hex-string; default 00:00:00:00; inet:domain-name; description "mask value 0x00000000";} "Specifies the identity as a Fully-Qualified Domain Name (FQDN) string. An example is: example.com. The string MUST not contain any terminators (e.g., NULL, CR, etc.)."; }

      container spd-lifetime-hard
                                leaf rfc822-address-string { type string; description "SPD lifetime hard state data";
         uses lifetime; "Specifies the identity as a fully-qualified RFC822 email address string. An example is, jsmith@example.com. The string MUST not contain any terminators (e.g., NULL, CR, etc.)."; }
                                leaf action {type lifetime-action; dnX509 { type string; description "action lifetime";} "Specifies the identity as a distinguished name in the X.509 tradition."; }

      container spd-lifetime-soft
                                leaf id_key { type string; description "SPD lifetime hard state data";
         uses lifetime; "Key id"; }
                                leaf action {type lifetime-action; id_null { type empty; description "action lifetime";} "RFC 7619" ; }
                                leaf user_fqdn { type string; description "User FQDN"; }

      // State data
      container spd-lifetime-current
                        }
                        leaf my-identifier {
         uses lifetime;
         config false; type string; mandatory true; description "SPD lifetime current state data"; "id used for authentication"; }
                } /* grouping ipsec-policy-grouping */

                /*################ end SPD grouping PAD ##################*/

                /*################## IKEv2-grouping ##################*/
                grouping isakmp-proposal ike-proposal {
                        description "ISAKMP "IKEv2 proposal grouping";
         leaf phase1-lifetime

                        container ike-sa-lifetime-hard { type uint32; mandatory true;
                                description "lifetime for IKE Phase 1 SAs";} "IKE SA lifetime hard";
                                uses ic:lifetime;
                        }

                        container ike-sa-lifetime-soft {
                                description "IPsec SA lifetime soft";
                                uses ic:lifetime;
                                leaf action {type ic:lifetime-action; description "Action lifetime";}
                        }

                        leaf-list phase1-authalg ike-sa-authalg { type integrity-algorithm-t; ic:integrity-algorithm-t; description "Auth algorigthm for IKE Phase 1 SAs";} SA";}
                        leaf-list phase1-encalg ike-sa-encalg { type encryption-algorithm-t; ic:encryption-algorithm-t; description "Auth algorigthm for IKE Phase 1 SAs";}
                        leaf combined-enc-intr { type boolean; description "Combined mode algorithms (encryption and integrity).";}
         leaf dh_group { type uint32; mandatory true; description "Group number for Diffie Hellman Exponentiation";}
                        leaf half-open-ike-sa-timer { type uint32; description "Set the half-open IKE SA timeout duration" ; }
                        leaf half-open-ike-sa-cookie-threshold { type uint32; description "Number of half-open IKE SAs that activate the cookie mechanism." ; }
                } /* list isakmp-proposal */

                grouping phase2-info ike-child-sa-info {
                        description "IKE Phase 2 "IPsec SA Information";
                        leaf-list pfs_group pfs_groups { type uint32; pfs-group; description "If non-zero, require perfect forward secrecy when requesting new SA. The non-zero value is the required group number"; }

                        container ipsec-sad-lifetime-hard child-sa-lifetime-soft {
                                description "IPsec SA lifetime hard"; soft";
                                uses lifetime; ic:lifetime;
                                leaf action {type lifetime-action; ic:lifetime-action; description "action lifetime";}
                        }

                        container ipsec-sad-lifetime-soft child-sa-lifetime-hard {
                                description "IPsec SA lifetime soft";
                                 uses lifetime;
                                 leaf hard. The action {type lifetime-action; description "action lifetime";} will be to terminate the IPsec SA.";
                                uses ic:lifetime;
                        }
                }

   grouping local-grouping

                /*################## End IKEv2-grouping ##################*/

                container ikev2 {

                        description "Configure the local peer in an IKE connection"; IKEv2 software";

                        container local pad {
                                description "Local container";
         choice my-identifier-type {
            default ipv4;
            case ipv4 "Configure Peer Authorization Database (PAD)";
                                list pad-entry {
                                        key "pad-entry-id";
                                        ordered-by user;
                                        description "Peer Authorization Database (PAD)";
                                        leaf ipv4 pad-entry-id { type inet:ipv4-address; uint64; description "IPv4 dotted-decimal address"; }
            }
            case ipv6 { "SAD index. ";}
                                        uses identity-grouping;
                                        leaf ipv6 pad-auth-protocol { type inet:ipv6-address; auth-protocol-type; description "numerical IPv6 address"; "IKEv2, etc. ";}
                                        uses auth-method-grouping;
                                }
                        }
            case fqdn

                        list ike-conn-entry {
                                key "conn-name";
                                description "IKE peer connection information";
                                leaf fqdn conn-name  { type inet:domain-name; string; mandatory true; description "Fully Qualifed Domain name "; }
            }
            case dn "Name of IKE connection";}
                                leaf autostartup { type type-autostartup; mandatory true; description "if True: automatically start tunnel at startup; else we do lazy tunnel setup based on trigger from datapath";}
                                leaf initial-contact {type boolean; default false; description "This IKE SA is the only currently active between the authenticated identities";}
                                leaf dn version {
                                        type string; enumeration {
                                                enum ikev2 {value 2; description "Domain name"; "IKE version 2";}
                                        }
                                        description "IKE version";
                                }
            case user_fqdn {

                                leaf user_fqdn ike-fragmentation { type string; boolean; description "User FQDN"; } "Whether to use IKEv2 fragmentation as per RFC 7383 (TRUE or FALSE)"; }
                                uses ike-proposal;

                                container local {
                                        description "Local ID type";
         } peer connection information";
                                        leaf my-identifier local-pad-id { type string; mandatory true; uint64; description "Local id used for authentication";}
      } " ";}
                                } // local-grouping

   grouping remote-grouping {
      description "Configure the remote peer in an IKE connection";

                                container remote {
                                        description "Remote container";
         choice my-identifier-type {
            default ipv4;
            case ipv4 { peer connection information";
                                        leaf ipv4 remote-pad-id { type inet:ipv4-address; uint64; description "IPv4 dotted-decimal address"; } " ";}
                                }
            case ipv6

                                uses ic:encap;

                                container spd {
               leaf ipv6
                                        description "Configure the Security Policy Database (SPD)";
                                        list spd-entry { type inet:ipv6-address;
                                                key "spd-entry-id";
                                                uses ic:ipsec-policy-grouping;
                                                ordered-by user;
                                                description "numerical IPv6 address"; "List of SPD entries";
                                        }
                                }
            case fqdn

                                container ike-sa-state {
                                        container uptime {
                                                description "IKE service uptime";
                                                leaf fqdn running { type inet:domain-name; yang:date-and-time;  description "Fully Qualifed Domain name "; }
            }
            case dn { "Relative uptime";}
                                                leaf dn since   { type string; yang:date-and-time;  description "Domain name"; } "Absolute uptime";}
                                        }
            case user_fqdn {

                                        leaf user_fqdn initiator { type string; boolean; description "User FQDN"; }
            } "It is acting as initiator in this connection";}
                                        leaf initiator-ikesa-spi {type uint64; description "Local ID type";
         } "Initiator's IKE SA SPI";}
                                        leaf my-identifier { type string; mandatory true; responder-ikesa-spi {type uint64; description "Local id used for authentication"; }
      }
   } // remote-grouping

   /*################## End IKEv2-groupingUMU ##################*/

   /*################# Register grouping #################*/

   typedef sadb-msg-type {

      type enumeration {
         enum sadb_reserved { "Responsder's IKE SA SPI";}
                                        leaf nat-local {type boolean; description "SADB_RESERVED";}
         enum sadb_getspi { "YES, if local endpoint is behind a NAT";}
                                        leaf nat-remote {type boolean; description "SADB_GETSPI";}
         enum sadb_update { "YES, if remote endpoint is behind a NAT";}
                                        leaf nat-any {type boolean; description "SADB_UPDATE";}
         enum sadb_add { "YES, if both local and remote endpoints are behind a NAT";}

                                        uses ic:encap;

                                        leaf established {type uint64; description "Seconds the IKE SA has been established";}
                                        leaf rekey-time {type uint64; description "SADB_ADD";}
         enum sadb_delete { "Seconds before IKE SA gets rekeyed";}
                                        leaf reauth-time {type uint64; description "SADB_DELETE"; }
         enum sadb_get "Seconds before IKE SA gets re-authenticated";}
                                        list child-sas {
                                                container spis{
                                                        description "SADB_GET"; }
         enum sadb_acquire { "IPsec SA's SPI '";
                                                        leaf spi-in {type ic:ipsec-spi;  description "SADB_ACQUIRE"; }
         enum sadb_register { "Security Parameter Index for inbound IPsec SA";}
                                                        leaf spi-out {type ic:ipsec-spi;  description "SADB_REGISTER"; "Security Parameter Index for the corresponding outbound IPsec SA";}

                                                }
         enum sadb_expire {
                                                description "SADB_EXPIRE"; "State data about IKE CHILD SAs";
                                        }
         enum sadb_flush {
                                        config false;
                                        description "SADB_FLUSH"; "IKE state data";
                                }
         enum sadb_dump { description "SADB_DUMP"; /* ike-sa-state */
                        }
         enum sadb_x_promisc { /* ike-conn-entries */

                        container number-ike-sas{
                                leaf total {type uint32; description "SADB_X_PROMISC"; }
         enum sadb_x_pchange { "Total number of IKEv2 SAs";}
                                leaf half-open {type uint32; description "SADB_X_PCHANGE"; }
         enum sadb_max{ "Number of half-open IKEv2 SAs";}
                                leaf half-open-cookies {type uint32; description "SADB_MAX"; }
      } "Number of half open IKE SAs with cookie activated" ;}
                                config false;
                                description "PF_KEY base message types"; "Number of IKE SAs";
                        }

   typedef sadb-msg-satype {
      type enumeration {
         enum sadb_satype_unspec { description "SADB_SATYPE_UNSPEC";
                }
         enum sadb_satype_ah { description "SADB_SATYPE_AH";  /* container ikev2 */
        }
         enum sadb_satype_esp

        <CODE ENDS>

Appendix C.  Appendix C: YANG model for IKE-less case

        <CODE BEGINS> file "ietf-ipsec-ikeless@2019-03-11.yang"

        module ietf-ipsec-ikeless { description "SADB_SATYPE_ESP"; }
         enum sadb_satype_rsvp

                yang-version 1.1;
                namespace "urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless";

                prefix "ipsec-ikeless";

                import ietf-yang-types { description "SADB_SATYPE_RSVP"; prefix yang; }
         enum sadb_satype_ospfv2

                import ietf-ipsec-common { description "SADB_SATYPE_OSPFv2";
                        prefix ic;
                        reference "Common Data model for SDN-based IPSec configuration";
                }
         enum sadb_satype_ripv2 {

                organization "IETF I2NSF (Interface to Network Security Functions) Working Group";

                contact
                " Rafael Marin Lopez
                Dept. Information and Communications Engineering (DIIC)
                Faculty of Computer Science-University of Murcia
                30100 Murcia - Spain
                Telf: +34868888501
                e-mail: rafa@um.es

                Gabriel Lopez Millan
                Dept. Information and Communications Engineering (DIIC)
                Faculty of Computer Science-University of Murcia
                30100 Murcia - Spain
                Tel: +34 868888504
                email: gabilm@um.es

                Fernando Pereniguez Garcia
                Department of Sciences and Informatics
                University Defense Center (CUD), Spanish Air Force Academy, MDE-UPCT
                30720 San Javier - Spain
                Tel: +34 968189946
                email: fernando.pereniguez@cud.upct.es
                ";

                description "SADB_SATYPE_RIPv2"; }
         enum sadb_satype_mip "Data model for IKE-less case";

                revision "2019-03-11" {
                        description "SADB_SATYPE_MIP"; "Revision";
                        reference "";
                }
         enum sadb_satype_max

                /*################## SAD grouping ####################*/
                grouping ipsec-sa-grouping {
                        description "SADB_SATYPE_MAX"; }
      }
      description "PF_KEY "Configure Security Association types";
   }

   grouping base-grouping { (SA). Section 4.4.2.1 in RFC 4301";

                        leaf sad-entry-id {type uint64; description "Configuration for "This value identifies a specific entry in the  message header format";
      list base-list {
         key "version"; SAD";}
                        leaf version spi { type string; ic:ipsec-spi;  description "Version of PF_KEY (MUST "Security Parameter Index. This may not be PF_KEY_V2)"; } unique for a particular SA";}
                        leaf msg_type seq-number { type sadb-msg-type; uint64; description "Identifies the type "Current sequence number of message"; IPsec packet."; }
                        leaf msg_satype seq-number-overflow-flag { type sadb-msg-satype; boolean; description "Defines "The flag indicating whether overflow of the type sequence number counter should prevent transmission of Security Association"; additional packets on the SA, or whether rollover is permitted."; }
                        leaf msg_seq anti-replay-window { type uint32; description "Sequence number of this message."; uint16 { range "0 | 32..1024"; } description "Configuration for a specific message header format";
      } "Anti replay window size"; }

     grouping algorithm-grouping {
      description "List of supported authentication and encryptation algorithms";

      container algorithm-supported {
         description "lists of encryption and authentication algorithms";
         list enc-algs {
            key "name";
                        leaf name { type encryption-algorithm-t; spd-entry-id {type uint64; description "Name of encryption algorithm"; } "This value links the SA with the SPD entry";}

                        uses ic:selector-grouping;

                        leaf ivlen security-protocol { type uint8; ic:ipsec-protocol; description "Length "Security protocol of the initialization vector to be used for the algorithm"; IPsec SA: Either AH or ESP."; }
            leaf min-bits

                        container sad-lifetime-hard { type uint16;
                                description "The minimun acceptable key length, in bits"; "SAD lifetime hard state data. The action associated is terminate.";
                                uses ic:lifetime;
                        }
            leaf max-bits
                        container sad-lifetime-soft { type uint16;
                                description "The maximun acceptable key length, in bits"; } "SAD lifetime hard state data";
                                uses ic:lifetime;
                                leaf action {type ic:lifetime-action; description "list of encryption algorithm supported "; "action lifetime";}
                        }
         list auth-algs {
            key "name";

                        leaf name mode { type integrity-algorithm-t; ic:ipsec-mode; description "Name of authentication algorithm";} "SA Mode"; }
                        leaf ivlen statefulfragCheck { type uint8; boolean; description "Length of the initialization vector "Indicates whether (TRUE) or not (FALSE) stateful fragment checking (RFC 4301) applies to be used for the algorithm"; this SA."; }

                        leaf min-bits dscp { type uint16; yang:hex-string; description "The minimun acceptable key length, in bits"; "DSCP value"; }
                        leaf max-bits path-mtu { type uint16; description "The maximun acceptable key length, in bits"; }
            description "list "Maximum size of authentication algorithm supported ";
         }
     } an IPsec packet that can be transmitted without fragmentation"; }
   /*################# End Register grouping #################*/

   /*################## ipsec ##################*/

                        container ietf-ipsec tunnel {
                                when "../mode = 'TUNNEL'";
                                uses ic:tunnel-grouping;
                                description "Main IPsec "Container for tunnel grouping";
                        }

                        uses ic:encap;

                        // STATE DATA for SA
                        container "; sad-lifetime-current {
                                uses ic:lifetime;
                                config false;
                                description "SAD lifetime current state data";
                        }

                        container ikev2 stats {
         if-feature case1; // xfrm.h
                                leaf replay-window {type uint32; default 0; description "Configure " "; }
                                leaf replay {type uint32; default 0; description "packets detected out of the IKEv2"; replay window and dropped because they are replay packets";}
                                leaf failed {type uint32; default 0; description "packets detected out of the replay window ";}
                                config false;
                                description "SAD statistics";
                        }

                        container ike-connection replay_state { // xfrm.h
                                leaf seq {type uint32; default 0; description "IKE connections configuration";

            list ike-conn-entries {
               key "conn-name"; "input traffic sequence number when anti-replay-window != 0";}
                                leaf oseq {type uint32; default 0; description "IKE peer connetion information"; "output traffic sequence number";}
                                leaf conn-name bitmap {type uint32; default 0; description "";}
                                config false;
                                description "Anti-replay Sequence Number state";
                        }

                        container replay_state_esn { type string; mandatory true; // xfrm.h
                                leaf bmp-len {type uint32; default 0; description "Name of IKE connection";} "bitmap length for ESN"; }
                                leaf autostartup oseq { type type-autostartup; mandatory true; uint32; default 0; description "if True: automatically start tunnel at startup; else we do lazy tunnel setup based on trigger from datapath";} "output traffic sequence number"; }
                                leaf nat-traversal oseq-hi { type boolean; uint32; default false; 0; description "Enable/Disable NAT traversal"; ""; }
                                leaf initial-contact seq-hi { type uint32; default 0; description ""; }
                                leaf replay-window {type boolean; uint32; default false; 0; description "This IKE SA is the only currently active between the authenticated identities";}

               container encap ""; }
                                leaf-list bmp {
                  when "../nat-traversal = 'true'"; type uint32; description "Encapsulation container";
                  leaf espencap "bitmaps for ESN (depends on bmp-len) "; }
                                config false;
                                description "Anti-replay Extended Sequence Number (ESN) state";
                        }

                }
                /*################## end SAD grouping ##################*/

                /*################# Register grouping #################*/
                typedef sadb-msg-type {
                        type esp-encap; description "ESP in TCP, ESP in UDP or ESP in TLS";}
                  leaf sport {type inet:port-number; enumeration {
                                enum sadb_acquire { description "Encapsulation source port";}
                  leaf dport {type inet:port-number; "SADB_ACQUIRE"; }
                                enum sadb_expire { description "Encapsulation destination port"; "SADB_EXPIRE"; }
                        }
                  leaf oaddr {type inet:ip-address;
                        description "Encapsulation Original Address ";} "Notifications (PF_KEY message types) that must be forwarded by the NSF to the controller in IKE-less case";
                }

               leaf version

                typedef sadb-msg-satype {
                         type enumeration {
                                enum ikev2 {value 2; sadb_satype_unspec { description "IKE version 2";} "SADB_SATYPE_UNSPEC"; }
                                enum sadb_satype_ah { description "IKE version"; "SADB_SATYPE_AH"; }

               uses isakmp-proposal;
               uses local-grouping;
               uses remote-grouping;
               uses phase2-info;

               container ike-stats {
                     container uptime
                                enum sadb_satype_esp { description "IKE service uptime";
                          leaf running "SADB_SATYPE_ESP"; }
                                enum sadb_satype_rsvp { type yang:date-and-time; description "Relative uptime";}
                          leaf since "SADB_SATYPE_RSVP"; }
                                enum sadb_satype_ospfv2 { type yang:date-and-time; description "Absolute uptime";} "SADB_SATYPE_OSPFv2"; }
                     leaf initiator
                                enum sadb_satype_ripv2 { type boolean; description "It is acting as initiator in this connection";}
                     leaf initiator-spi {type uint64; "SADB_SATYPE_RIPv2"; }
                                enum sadb_satype_mip { description "Initiator's IKE SA SPI";}
                     leaf responder-spi {type uint64; "SADB_SATYPE_MIP"; }
                                enum sadb_satype_max { description "Responsder's IKE SA SPI";}
                     leaf nat-local {type boolean; "SADB_SATYPE_MAX"; }
                        }
                        description "YES, if local endpoint is behind a NAT";}
                     leaf nat-remote {type boolean; "PF_KEY Security Association types";
                }

                grouping base-grouping {
                        description "YES, if remote endpoint is behind a NAT";} "Configuration for the  message header format";
                        list base-list {
                                         key "version";
                                         leaf nat-any {type boolean; version { type string; description "YES, if both local and remote endpoints are behind a NAT";} "Version of PF_KEY (MUST be PF_KEY_V2)"; }
                                         leaf established {type uint64; msg_type { type sadb-msg-type; description "Seconds "Identifies the IKE SA has been established";} type of message"; }
                                         leaf rekey-time {type uint64; msg_satype { type sadb-msg-satype; description "Seconds before IKE SA gets rekeyed";} "Defines the type of Security Association"; }
                                         leaf reauth-time {type uint64; description "Seconds before IKE SA gets re-authenticated";}
                     list child-sas msg_seq {
                          container spis{ type uint32; description "IKE active SA's SPI '";
                              leaf spi-in {type ipsec-spi; "Sequence number of this message."; }
                                         description "Security Parameter Index "Configuration for Inbound a specific message header format";
                        }
                }
                /*################# End Register grouping #################*/

                /*################## IPsec SA";}
                              leaf spi-out {type ipsec-spi; configuration ##################*/
                container ietf-ipsec {
                        description "Security Parameter Index for the corresponding outbound IPsec SA";}
                          } "IPsec configuration";

                        container spd {
                                                description "State data about IKE CHILD SAs";
                    }
                    config false; "Configure the Security Policy Database (SPD)";
                                                list spd-entry {
                                                   key "spd-entry-id";
                                                   uses ic:ipsec-policy-grouping;
                                                   ordered-by user;
                                                   description "IKE state data";
                } /* ike-stats */ "List of SPD entries";
                                                } /* ike-conn-entries */
                        } /*

                        container ike-connection */ sad {
                                description "Configure the IPSec Security Association Database (SAD)";

                                list sad-entry {
                                        key "sad-entry-id";

                                        uses ipsec-sa-grouping;

                                        container number-ike-sas{
            leaf total {type uint32; ah-sa {
                                                when "../security-protocol = 'ah'";
                                                description "Total number of IKEv2 SAs";} "Configure Authentication Header (AH) for SA";
                                                container integrity {
                                                        description "Configure integrity for IPSec Authentication Header (AH)";
                                                        leaf half-open {type uint32; integrity-algorithm { type ic:integrity-algorithm-t; description "Total number of half-open IKEv2 SAs";}
            config false; "Configure Authentication Header (AH)."; }
                                                        leaf key { type string; description "Number of IKE SAs"; "AH key value";}
                                                }
                                        }  /*

                                        container ikev2 */

      container ipsec esp-sa {
                                                when "../security-protocol = 'esp'";
                                                description "Configuration IPsec"; "Set IPSec Encapsulation Security Payload (ESP)";

                                                container spd encryption {
                                                        description "Configure the Security Policy Database (SPD)";
            list spd-entry encryption for IPSec Encapsulation Secutiry Payload (ESP)";
                                                        leaf encryption-algorithm {
               key "rule-number";
               uses ipsec-policy-grouping;
               ordered-by user; type ic:encryption-algorithm-t; description "List of SPD entries";
            } "Configure ESP encryption"; }
         container sad
                                                        leaf key { type yang:hex-string; description "Configure the IPSec Security Association Database (SAD)";
            list sad-entry { "ESP encryption key "spi";
               uses ipsec-sa-grouping; value";}
                                                        leaf iv {type yang:hex-string; description "List of SAD entries"; "ESP encryption IV value"; }
                                                }

                                                container pad integrity {
            if-feature case1;
                                                        description "Configure Peer Authorization Database (PAD)";

            list pad-entries authentication for IPSec Encapsulation Secutiry Payload (ESP)";
                                                        leaf integrity-algorithm {
               key "pad-entry-id";
               ordered-by user; type ic:integrity-algorithm-t; description "Peer Authorization Database (PAD)"; "Configure Authentication Header (AH)."; }
                                                        leaf pad-entry-id key { type uint64; yang:hex-string; description "SAD index. ";}
               uses identity-grouping; "ESP integrity key value";}
                                                }
                                                /* With AEAD algorithms, the integrity node is not used */

                                                leaf pad-auth-protocol combined-enc-intr { type auth-protocol-type; boolean; description "IKEv1, IKEv2, KINK, etc. ";}
               uses auth-method-grouping; "ESP combined mode algorithms. The algorithm is specified in encryption-algorithm";}
                                        }
                                        description "List of SAD entries";
                                }
                        }
                } /* container ietf-ipsec */

                /*################## RPC and Notifications ##################*/

   /* Note: not yet completed */

                // Those These RPCs are needed by a Security Controller in IKEless case 2 */

   rpc sadb_register {
      description "Allows netconf to register its key socket as able to acquire new security associations for the kernel";
      input {
         uses base-grouping;
      }
      output {
         uses base-grouping;
         uses algorithm-grouping;
      }
   }

                notification spdb_expire {
                        description "A SPD entry has expired";
                        leaf index { type uint64; description "SPD index. RFC4301 does not mention an index however real implementations (e.g. XFRM or PFKEY_v2 with KAME extensions provide a policy index to refer a policy. "; }
                }

                notification sadb_acquire {
                        description "A IPsec SA is required ";
                        uses base-grouping;
                        uses ic:selector-grouping; // To indicate the concrete traffic selector of the policy that triggered this acquire.
                }

                notification sadb_expire {
                        description "A IPsec SA expiration (soft or hard)";

                        uses base-grouping;
                        leaf spi { type ipsec-spi; ic:ipsec-spi;  description "Security Parameter Index";}
                        leaf anti-replay-window { type uint16 { range "0 | 32..1024"; } description "Anti replay window"; }

                        leaf state {type sa-state; description "current state of SA (mature, larval, dying or dead)"; }

      leaf encryption-algorithm { type encryption-algorithm-t; ic:encryption-algorithm-t; description "encryption algorithm of the expired SA"; }
                        leaf authentication-algorithm { type integrity-algorithm-t; ic:integrity-algorithm-t; description "authentication algorithm of the expired SA"; }

                        container sad-lifetime-hard {
                                description "SAD lifetime hard state data";
                                uses lifetime; ic:lifetime;
                        }
                        container sad-lifetime-soft {
                                description "SAD lifetime hard soft state data";
                                uses lifetime; ic:lifetime;
                        }

                        container sad-lifetime-current {
                                description "SAD lifetime current state data";
                                uses lifetime; ic:lifetime;
                        }

                }

                notification sadb_bad-spi {
                        description "....."; "Notifiy when the NSF receives a packet with an incorrect SPI (i.e. not present in the SAD)";
                        leaf state { type ipsec-spi; ic:ipsec-spi; mandatory "true"; description "Notify when a SPI"; } "SPI number contained in the erroneous IPsec packet"; }
                }  /*module

        }/*module ietf-ipsec*/

        <CODE ENDS>

Authors' Addresses

   Rafa Marin-Lopez
   University of Murcia
   Campus de Espinardo S/N, Faculty of Computer Science
   Murcia  30100
   Spain

   Phone: +34 868 88 85 01
   EMail: rafa@um.es

   Gabriel Lopez-Millan
   University of Murcia
   Campus de Espinardo S/N, Faculty of Computer Science
   Murcia  30100
   Spain

   Phone: +34 868 88 85 04
   EMail: gabilm@um.es

   Fernando Pereniguez-Garcia
   University Defense Center
   Spanish Air Force Academy, MDE-UPCT
   San Javier (Murcia)  30720
   Spain

   Phone: +34 968 18 99 46
   EMail: fernando.pereniguez@cud.upct.es