I2NSF R. Marin-Lopez
Internet-Draft G. Lopez-Millan
Intended status: Standards Track University of Murcia
Expires: February 6, 2020 F. Pereniguez-Garcia
University Defense Center
August 5, 2019
Software-Defined Networking (SDN)-based IPsec Flow Protection
draft-ietf-i2nsf-sdn-ipsec-flow-protection-07
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.
The document focuses on the NSF Facing Interface by providing models
for configuration and state data 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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This Internet-Draft will expire on February 6, 2020.
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements Language . . . . . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. Objectives . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. SDN-based IPsec management description . . . . . . . . . . . 6
5.1. IKE case: IKE/IPsec in the NSF . . . . . . . . . . . . . 6
5.1.1. Interface Requirements for IKE case . . . . . . . . . 7
5.2. IKE-less case: IPsec (no IKEv2) in the NSF. . . . . . . . 7
5.2.1. Interface Requirements for IKE-less case . . . . . . 8
5.3. IKE case vs IKE-less case . . . . . . . . . . . . . . . . 9
5.3.1. Rekeying process. . . . . . . . . . . . . . . . . . . 10
5.3.2. NSF state loss. . . . . . . . . . . . . . . . . . . . 12
5.3.3. NAT Traversal . . . . . . . . . . . . . . . . . . . . 12
5.3.4. NSF Discovery . . . . . . . . . . . . . . . . . . . . 13
6. YANG configuration data models . . . . . . . . . . . . . . . 13
6.1. IKE case model . . . . . . . . . . . . . . . . . . . . . 14
6.2. IKE-less case model . . . . . . . . . . . . . . . . . . . 17
7. Use cases examples . . . . . . . . . . . . . . . . . . . . . 20
7.1. Host-to-host or gateway-to-gateway under the same
Security Controller . . . . . . . . . . . . . . . . . . . 20
7.2. Host-to-host or gateway-to-gateway under different
Security Controllers . . . . . . . . . . . . . . . . . . 24
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 26
9. Security Considerations . . . . . . . . . . . . . . . . . . . 27
9.1. IKE case . . . . . . . . . . . . . . . . . . . . . . . . 28
9.2. IKE-less case . . . . . . . . . . . . . . . . . . . . . . 29
9.3. YANG modules . . . . . . . . . . . . . . . . . . . . . . 29
10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 31
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 31
11.1. Normative References . . . . . . . . . . . . . . . . . . 31
11.2. Informative References . . . . . . . . . . . . . . . . . 32
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Appendix A. Appendix A: Common YANG model for IKE and IKE-less
cases . . . . . . . . . . . . . . . . . . . . . . . 35
Appendix B. Appendix B: YANG model for IKE case . . . . . . . . 48
Appendix C. Appendix C: YANG model for IKE-less case . . . . . . 67
Appendix D. Example of IKE case, tunnel mode (gateway-to-
gateway) with X.509 certificate authentication. . . 77
Appendix E. Example of IKE-less case, transport mode (host-to-
host). . . . . . . . . . . . . . . . . . . . . . . . 81
Appendix F. Examples of notifications. . . . . . . . . . . . . . 85
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 86
1. Introduction
Software-Defined Networking (SDN) is an architecture that enables
users to directly program, orchestrate, control and manage network
resources through software. The SDN paradigm relocates the control
of network resources to a dedicated network element, namely SDN
Controller. The SDN controller (or Security Controller in the
context of this document) 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].
Recently, several network scenarios are considering a centralized way
of managing different security aspects. For example, Software-
Defined WANs (SD-WAN), an 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 such as IPsec SA management 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 following the SDN
paradigm.
IPsec architecture [RFC4301] defines 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 and centralized entity: the
Security Controller.
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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 Security 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, IKE case requires the provision of SPD and
PAD entries, the IKE credential and information related with the IKE
negotiation (e.g. IKE_SA_INIT). 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, Appendix B and Appendix C). Examples of the usage
of these models can found in Appendix D, Appendix E and Appendix F.
This document considers two typical scenarios to manage autonomously
IPsec SAs: gateway-to-gateway and host-to-host [RFC6071]. In these
cases, hosts, 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. The analysis of the host-to-gateway
(roadwarrior) scenario is out of scope of this document.
Finally, this work pays attention to the challenge "Lack of Mechanism
for Dynamic Key Distribution to NSFs" defined in [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 [RFC8192].
2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in RFC
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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. An entity 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 fall 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. raw RSA/ECDSA keys or X.509
certificates), Diffie-Hellman (DH) groups, IPsec SAs parameters
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
(traffic selectors information), inbound and outboud IPsec SAs,
etc.
o Security Associations Database (SAD). It includes information
about IPsec SAs, such as SPI, destination addresses,
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authentication and encryption algorithms and keys to protect IP
flows.
o Peer Authorization Database (PAD). It provides the link between
the SPD and a security association management protocol. It is
used when the NSF deploys IKE implementation (IKE case).
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, in
order to protect specific data flows.
o To define the interfaces required to manage and monitor the IPsec
Security Associations (SA) 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, depending on
whether the NSF ships an IKEv2 implementation or not: IKE case and
IKE-less case.
5.1. 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 IPsec connection information (determining which nodes need
to start an IKE/IPsec session, deriving and delivering IKE
Credentials such as a pre-shared key, certificates, etc.), and
applying other IKE configuration parameters (e.g. cryptographic
algorithms for establishing an IKE SA) 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, [RFC8192]), and the Security
Controller translates these 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.
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+-------------------------------------------+
|IPsec Management/Orchestration Application | Client or
| I2NSF Client | App Gateway
+-------------------------------------------+
| Client Facing Interface
+-------------------------------------------+
Vendor | Application Support |
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: IKE case: IKE/IPsec in the NSF
5.1.1. Interface Requirements for IKE case
SDN-based IPsec flow protection services provide dynamic and flexible
management of IPsec SAs in flow-based NSFs. In order to support this
capability in IKE case, the following interface requirements need to
be met:
o A YANG data model for IKEv2, SPD and PAD configuration data, and
for IKE state data.
o In scenarios where multiple Security 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 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 NSFs. That
is, the may need to agree on whether IKEv2 authentication will be
based on raw public keys, pre-shared keys, etc. In case of using
pre-shared keys they will have to agree in the PSK.
5.2. 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
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management of IPsec SAs by populating and managing the SPD and the
SAD.
+-----------------------------------------+
| IPsec Management Application | Client or
| I2NSF Client | App Gateway
+-----------------------------------------+
| Client Facing Interface
+-----------------------------------------+
Vendor| Application Support |
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: 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 these 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 IKE-less case
In order to support the IKE-less case, the following requirements
need to be met:
o A YANG data model for configuration data for SPD and SAD and for
state data for 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 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.
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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 the same key.
o Generation of pseudo-random cryptographic keys for the IPsec SAs.
o Rekey of the IPsec SAs based on notifications from the NSF (i.e.
expire).
o Generation of the IPsec SAs when required based on notifications
(i.e. sadb-acquire) from the NSF.
o NAT Traversal discovery and management.
Additionally to these functions, another set of tasks must be
performed by the Security Controller (non-exhaustive list):
o IPsec SA's SPI random generation.
o Cryptographic algorithm/s selection.
o Usage of extended sequence numbers.
o Establishment of proper traffic selectors.
5.3. IKE case vs IKE-less case
In principle, IKE case is easier to deploy than 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 internal interface so that
the IKE configuration sent by the Security Controller can be enforced
in runtime.
Alternatively, 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 and managing
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 in comparison with IKE case.
For example, the Security Controller have to deal with the latency
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existing in the path between the Security Controller and the NSF in
order to solve tasks such as, rekey or creation and installation of
new IPsec SAs. However, this is not specific to our contribution but
a general aspect in any SDN-based network. In summary, this overload
may create some scalability and performance issues when the number of
NSFs is high.
Nevertheless, literature around SDN-based network management using a
centralized Security Controller is aware about scalability and
performance issues and solutions have been already provided and
discussed (e.g. hierarchical Security Controllers; having multiple
replicated Security Controllers, dedicated high-speed management
networks, etc). In the context of SDN-based IPsec management, one
way to reduce the latency and alleviate some performance issues can
be the installation of the IPsec policies and IPsec SAs at the same
time (proactive mode, as described in Section 7.1) instead of waiting
for notifications (e.g. a notification sadb-acquire when a new IPsec
SA is required) to proceed with the IPsec SA installations (reactive
mode). Another way to reduce the overhead and the potential
scalability and performance issues in the Security Controller is to
apply the 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 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 rekey 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 9. The main
reason is that the NSFs are generating the session keys and not the
Security Controller.
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. Therefore, connections
will live unless something different is required by the administrator
or the Security Controller detects something wrong.
Traditionally, during a rekey process of the IPSec SA using IKE, a
bundle of inbound and outbound IPsec SAs is taken into account from
the perspective of one of the NSFs. For example, if the inbound
IPsec SA expires both the inbound and outbound IPsec SA are rekeyed
at the same time in that NSF. However, when IKE is not used, we have
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followed a different approach to avoid any packet loss during rekey:
the Security Controller installs first the new inbound SAs in both
NSFs and then, the outbound IPsec SAs.
In other words, for the 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 NSFs A and B, let
assume that SPIa1 identifies the inbound IPsec SA in A, and SPIb1 the
inbound IPsec SA in B. The rekeying process will take the following
steps:
1. The Security Controller chooses two random values as SPI for the
new inbound IPsec 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 Security Controller creates an inbound IPsec SA
with SPIa2 in A and another inbound IPsec SA in B with SPIb2. It
can send this information simultaneously to A and B.
2. Once the Security Controller receives confirmation from A and B,
the controller knows that the inbound IPsec A are correctly
installed. Then it proceeds to send in parallel to A and B, the
outbound IPsec SAs: it sends the outbound IPsec SA to A with
SPIb2 and the outbound IPsec SA to B with SPIa2. At this point
the new IPsec SAs are ready.
3. Once the Security Controller receives confirmation from A and B
that the outbound IPsec SAs have been installed, the Security
Controller, in parallel, deletes the old IPsec SAs from A
(inbound SPIa1 and outbound SPIb1) and B (outbound SPIa1 and
inbound SPIb1).
If some of the operations in step 1 fail (e.g. the NSF A reports an
error when the Security Controller is trying to install a new inbound
IPsec SA) the Security Controller must perform rollback operations by
removing any new inbound SA that had been successfully installed
during step 1.
If step 1 is successful but some of the operations in step 2 fails
(e.g. the NSF A reports an error when the Security Controller is
trying to install the new outbound IPsec SA), the Security Controller
must perform a rollback operation by deleting any new outbound SA
that had been successfully installed during step 2 and by deleting
the inbound SAs created in step 1.
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If the steps 1 an 2 are successful and the step 3 fails the Security
Controller will avoid any rollback of the operations carried out in
step 1 and step 2 since new and valid IPsec SAs were created and are
functional. The Security Controller may reattempt to remove the old
inbound and outbound SAs in NSF A and NSF B several times until it
receives a success or it gives up. In the last case, the old IPsec
SAs will be removed when the hard lifetime is reached.
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 the IKE case, and SPD and SAD
information in IKE-less case.
In both cases, the Security Controller is aware of the affected NSF
(e.g. the NETCONF/TCP connection is broken with the affected NSF, the
Security Controller is receiving sadb-bad-spi notification from a
particular NSF, etc.). Moreover, the Security Controller has a
register about all the NSFs that have IPsec SAs with the affected
NSF. Therefore, it knows the affected IPsec SAs.
In 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 for authentication) to the NSFs
which have IKEv2 SAs and IPsec SAs with the affected NSF. Finally,
the Security Controller will instruct the affected NSF to start the
IKEv2 negotiation with the new configuration.
In IKE-less case, if the Security Controller detects that a NSF has
lost the IPsec SAs it will delete the old IPsec SAs on the non-failed
nodes, established with the failed node (step 1). This prevents the
non-failed nodes from leaking plaintext. If the affected node comes
to live, the Security Controller will configure the new inbound IPsec
SAs between the affected node and all the nodes it was talking to
(step 2). After these inbound IPsec SAs have been established, the
Security Controller can configure the outbound IPsec SAs in parallel
(step 3).
Nevertheless other more optimized options can be considered (e.g.
making the IKEv2 configuration permanent between reboots).
5.3.3. NAT Traversal
In the IKE case, IKEv2 already provides 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
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the usage of UDP or TCP/TLS encapsulation for ESP packets ([RFC3948],
[RFC8229]). Note that the usage of IPsec transport mode when NAT is
required MUST NOT be used in this specification.
On the contrary, the IKE-less case 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 under its control. This view is built
either requesting information to the NSFs under its control, or
because these NSFs inform 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
[RFC8512] a data model for NAT management. The Security Controller
can use this NETCONF module with a NSF to collect NAT information or
even configure a NAT network. In any case, if this NETCONF module is
not available in the NSF and the Security Controller does not have a
mechanism to know whether a host is behind a NAT or not, then the IKE
case should be the right choice and not the IKE-less case.
5.3.4. NSF Discovery
The assumption in this document is that, for both cases, before a NSF
can operate in this system, it MUST be registered in the Security
Controller. In this way, when the NSF comes to live and establishes
a connection to the Security Controller, it knows that the NSF is
valid for joining the system.
Either during this registration process or when the NSF connects with
the Security Controller, the Security Controller MUST discover
certain capabilities of this NSF, such as what is the cryptographic
suite supported, authentication method, the support of the IKE case
or the IKE-less case, etc. This discovery process is out of the
scope of this document.
6. YANG configuration data models
In order to support the IKE and IKE-less cases we have modeled the
different parameters and values that must be configured to manage
IPsec SAs. Specifically, IKE requires modeling IKEv2, SPD and PAD,
while IKE-less case requires configuration models for the SPD and
SAD. We have defined three models: ietf-ipsec-common (Appendix A),
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ietf-ipsec-ike (Appendix B, IKE case), ietf-ipsec-ikeless
(Appendix C, IKE-less case). Since the model ietf-ipsec-common has
only typedef and groupings common to the other modules, we only show
a simplified view of the ietf-ipsec-ike and ietf-ipsec-ikeless
models.
6.1. IKE case model
The model related to IKEv2 has been extracted from reading IKEv2
standard in [RFC7296], and observing some open source
implementations, such as Strongswan [strongswan] or Libreswan
[libreswan].
The definition of the PAD model has been extracted from the
specification in section 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 ipsec-ike
+--rw pad
| +--rw pad-entry* [name]
| +--rw name string
| +--rw (identity)
| | +--:(ipv4-address)
| | | +--rw ipv4-address? inet:ipv4-address
| | +--:(ipv6-address)
| | | +--rw ipv6-address? inet:ipv6-address
| | +--:(fqdn-string)
| | | +--rw fqdn-string? inet:domain-name
| | +--:(rfc822-address-string)
| | | +--rw rfc822-address-string? string
| | +--:(dnx509)
| | | +--rw dnx509? string
| | +--:(gnx509)
| | | +--rw gnx509? string
| | +--:(id-key)
| | | +--rw id-key? string
| | +--:(id-null)
| | +--rw id-null? empty
| +--rw auth-protocol? auth-protocol-type
| +--rw peer-authentication
| +--rw auth-method? auth-method-type
| +--rw eap-method
| | +--rw eap-type uint8
| +--rw pre-shared
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| | +--rw secret? yang:hex-string
| +--rw digital-signature
| +--rw ds-algorithm? uint8
| +--rw (public-key)
| | +--:(raw-public-key)
| | | +--rw raw-public-key? binary
| | +--:(cert-data)
| | +--rw cert-data? ct:x509
| +--rw private-key? binary
| +--rw ca-data* ct:x509
| +--rw crl-data? ct:crl
| +--rw crl-uri? inet:uri
| +--rw oscp-uri? inet:uri
+--rw conn-entry* [name]
| +--rw name string
| +--rw autostartup? autostartup-type
| +--rw initial-contact? boolean
| +--rw version? auth-protocol-type
| +--rw fragmentation? boolean
| +--rw ike-sa-lifetime-soft
| | +--rw rekey-time? uint32
| | +--rw reauth-time? uint32
| +--rw ike-sa-lifetime-hard
| | +--rw over-time? uint32
| +--rw authalg* ic:integrity-algorithm-type
| +--rw encalg* ic:encryption-algorithm-type
| +--rw dh-group? pfs-group
| +--rw half-open-ike-sa-timer? uint32
| +--rw half-open-ike-sa-cookie-threshold? uint32
| +--rw local
| | +--rw local-pad-entry-name? string
| +--rw remote
| | +--rw remote-pad-entry-name? string
| +--rw encapsulation-type
| | +--rw espencap? esp-encap
| | +--rw sport? inet:port-number
| | +--rw dport? inet:port-number
| | +--rw oaddr* inet:ip-address
| +--rw spd
| | +--rw spd-entry* [name]
| | +--rw name string
| | +--rw ipsec-policy-config
| | +--rw anti-replay-window? uint64
| | +--rw traffic-selector
| | | +--rw local-subnet inet:ip-prefix
| | | +--rw remote-subnet inet:ip-prefix
| | | +--rw inner-protocol? ipsec-inner-protocol
| | | +--rw local-ports* [start end]
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| | | | +--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 processing-info
| | | +--rw action? ipsec-spd-action
| | | +--rw ipsec-sa-cfg
| | | +--rw pfp-flag? boolean
| | | +--rw ext-seq-num? boolean
| | | +--rw seq-overflow? boolean
| | | +--rw stateful-frag-check? boolean
| | | +--rw mode? ipsec-mode
| | | +--rw protocol-parameters? ipsec-protocol-parameters
| | | +--rw esp-algorithms
| | | | +--rw integrity* integrity-algorithm-type
| | | | +--rw encryption* encryption-algorithm-type
| | | | +--rw tfc-pad? boolean
| | | +--rw tunnel
| | | +--rw local inet:ip-address
| | | +--rw remote inet:ip-address
| | | +--rw df-bit? enumeration
| | | +--rw bypass-dscp? boolean
| | | +--rw dscp-mapping? yang:hex-string
| | | +--rw ecn? boolean
| | +--rw spd-mark
| | +--rw mark? uint32
| | +--rw mask? yang:hex-string
| +--rw child-sa-info
| | +--rw pfs-groups* pfs-group
| | +--rw child-sa-lifetime-soft
| | | +--rw time? uint32
| | | +--rw bytes? uint32
| | | +--rw packets? uint32
| | | +--rw idle? uint32
| | | +--rw action? ic:lifetime-action
| | +--rw child-sa-lifetime-hard
| | +--rw time? uint32
| | +--rw bytes? uint32
| | +--rw packets? uint32
| | +--rw idle? uint32
| +--ro state
| +--ro initiator? boolean
| +--ro initiator-ikesa-spi? ike-spi
| +--ro responder-ikesa-spi? ike-spi
| +--ro nat-local? boolean
| +--ro nat-remote? boolean
| +--ro encapsulation-type
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| | +--ro espencap? esp-encap
| | +--ro sport? inet:port-number
| | +--ro dport? inet:port-number
| | +--ro oaddr* inet:ip-address
| +--ro established? uint64
| +--ro current-rekey-time? uint64
| +--ro current-reauth-time? uint64
+--ro number-ike-sas
+--ro total? uint64
+--ro half-open? uint64
+--ro half-open-cookies? uint64
Appendix D shows an example of IKE case configuration for a NSF, in
tunnel mode (gateway-to-gateway), with NSFs authentication based on
X.509 certificates.
6.2. IKE-less case model
For this case, the definition of the SPD model has been mainly
extracted from the specification in section 4.4.1 and Appendix D in
[RFC4301], though with some simplications. For example, each IPsec
policy (spd-entry) contains one traffic selector, instead a list of
them. The reason is that we have observed real kernel
implementations only admit a traffic selector per IPsec policy.
The definition of the SAD model has been extracted from the
specification in section 4.4.2 in [RFC4301]. Note that this model
not only allows to associate an IPsec SA with its corresponding
policy through the specific traffic selector but also an identifier
(reqid).
The notifications model has been defined using as reference the
PF_KEYv2 standard in [RFC2367].
module: ietf-ipsec-ikeless
+--rw ipsec-ikeless
+--rw spd
| +--rw spd-entry* [name]
| +--rw name string
| +--rw direction? ic:ipsec-traffic-direction
| +--rw reqid? uint64
| +--rw ipsec-policy-config
| +--rw anti-replay-window? uint64
| +--rw traffic-selector
| | +--rw local-subnet inet:ip-prefix
| | +--rw remote-subnet inet:ip-prefix
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| | +--rw inner-protocol? ipsec-inner-protocol
| | +--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 processing-info
| | +--rw action? ipsec-spd-action
| | +--rw ipsec-sa-cfg
| | +--rw pfp-flag? boolean
| | +--rw ext-seq-num? boolean
| | +--rw seq-overflow? boolean
| | +--rw stateful-frag-check? boolean
| | +--rw mode? ipsec-mode
| | +--rw protocol-parameters?
| | +--rw esp-algorithms
| | | +--rw integrity* integrity-algorithm-type
| | | +--rw encryption* encryption-algorithm-type
| | | +--rw tfc-pad? boolean
| | +--rw tunnel
| | +--rw local inet:ip-address
| | +--rw remote inet:ip-address
| | +--rw df-bit? enumeration
| | +--rw bypass-dscp? boolean
| | +--rw dscp-mapping? yang:hex-string
| | +--rw ecn? boolean
| +--rw spd-mark
| +--rw mark? uint32
| +--rw mask? yang:hex-string
+--rw sad
+--rw sad-entry* [name]
+--rw name string
+--rw reqid? uint64
+--rw ipsec-sa-config
| +--rw spi uint32
| +--rw ext-seq-num? boolean
| +--rw seq-number-counter? uint64
| +--rw seq-overflow? boolean
| +--rw anti-replay-window? uint32
| +--rw traffic-selector
| | +--rw local-subnet inet:ip-prefix
| | +--rw remote-subnet inet:ip-prefix
| | +--rw inner-protocol? ipsec-inner-protocol
| | +--rw local-ports* [start end]
| | | +--rw start inet:port-number
| | | +--rw end inet:port-number
| | +--rw remote-ports* [start end]
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| | +--rw start inet:port-number
| | +--rw end inet:port-number
| +--rw protocol-parameters? ic:ipsec-protocol-parameters
| +--rw mode? ic:ipsec-mode
| +--rw esp-sa
| | +--rw encryption
| | | +--rw encryption-algorithm? ic:encryption-algorithm-type
| | | +--rw key? yang:hex-string
| | | +--rw iv? yang:hex-string
| | +--rw integrity
| | +--rw integrity-algorithm? ic:integrity-algorithm-type
| | +--rw key? yang:hex-string
| +--rw sa-lifetime-hard
| | +--rw time? uint32
| | +--rw bytes? uint32
| | +--rw packets? uint32
| | +--rw idle? uint32
| +--rw sa-lifetime-soft
| | +--rw time? uint32
| | +--rw bytes? uint32
| | +--rw packets? uint32
| | +--rw idle? uint32
| | +--rw action? ic:lifetime-action
| +--rw tunnel
| | +--rw local inet:ip-address
| | +--rw remote inet:ip-address
| | +--rw df-bit? enumeration
| | +--rw bypass-dscp? boolean
| | +--rw dscp-mapping? yang:hex-string
| | +--rw ecn? boolean
| +--rw encapsulation-type
| +--rw espencap? esp-encap
| +--rw sport? inet:port-number
| +--rw dport? inet:port-number
| +--rw oaddr* inet:ip-address
+--ro ipsec-sa-state
+--ro sa-lifetime-current
| +--ro time? uint32
| +--ro bytes? uint32
| +--ro packets? uint32
| +--ro idle? uint32
+--ro replay-stats
+--ro replay-window? uint64
+--ro packet-dropped? uint64
+--ro failed? uint32
+--ro seq-number-counter? uint64
notifications:
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+---n sadb-acquire
| +--ro ipsec-policy-name string
| +--ro traffic-selector
| +--ro local-subnet inet:ip-prefix
| +--ro remote-subnet inet:ip-prefix
| +--ro inner-protocol? ipsec-inner-protocol
| +--ro local-ports* [start end]
| | +--ro start inet:port-number
| | +--ro end inet:port-number
| +--ro remote-ports* [start end]
| +--ro start inet:port-number
| +--ro end inet:port-number
+---n sadb-expire
| +--ro ipsec-sa-name string
| +--ro soft-lifetime-expire? boolean
| +--ro lifetime-current
| +--ro time? uint32
| +--ro bytes? uint32
| +--ro packets? uint32
| +--ro idle? uint32
+---n sadb-seq-overflow
| +--ro ipsec-sa-name string
+---n sadb-bad-spi
+--ro spi uint32
Appendix E shows an example of IKE-less case configuration for a NSF,
in transport mode (host-to-host), with NSFs authentication based on
shared secrets. For the IKE-less case, Appendix F shows examples of
IPsec SA expire, acquire, sequence number overflow and bad SPI
notifications.
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 or gateway-to-gateway under the same Security
Controller
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+----------------------------------------+
| Security Controller |
| |
(1)| +--------------+ (2)+--------------+ |
Flow-based ------> |Translate into|--->| South. Prot. | |
Security. Pol. | |IPsec Policies| | | |
| +--------------+ +--------------+ |
| | | |
| | | |
+--------------------------|-----|-------+
| |
| (3) |
|-------------------------+ +---|
V V
+----------------------+ +----------------------+
| NSF A |<=======>| NSF B |
|IKEv2/IPsec(SPD/PAD) | |IKEv2/IPsec(SPD/PAD) |
+----------------------+ (4) +----------------------+
Figure 3: Host-to-host / gateway-to-gateway single Security
Controller for the IKE case.
Figure 3 describes the IKE case:
1. The administrator defines general flow-based security policies.
The Security Controller looks for the NSFs involved (NSF A and
NSF B).
2. The Security Controller generates IKEv2 credentials for them and
translates the policies into SPD and PAD entries.
3. The Security Controller inserts an IKEv2 configuration that
includes the SPD and PAD entries in both NSF A and NSF B. If
some of operations with NSF A and NSF B fail the Security
Controller will stop the process and perform a rollback operation
by deleting any IKEv2, SPD and PAD configuration that had been
successfully installed in NSF A or B.
4. If the previous step is successful, the flow is protected by
means of the IPsec SA established with IKEv2.
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+----------------------------------------+
| (1) Security Controller |
Flow-based | |
Security -----------| |
Policy | V |
| +---------------+ (2)+-------------+ |
| |Translate into |--->| South. Prot.| |
| |IPsec policies | | | |
| +---------------+ +-------------+ |
| | | |
| | | |
+-------------------------| --- |--------+
| |
| (3) |
|----------------------+ +--|
V V
+------------------+ +------------------+
| NSF A |<=====>| NSF B |
|IPsec(SPD/SAD) | 4) |IPsec(SPD/SAD) |
+------------------+ +------------------+
Figure 4: Host-to-host / gateway-to-gateway single Security
Controller for IKE-less case.
In the IKE-less case, flow-based security policies defined by the
administrator are 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, the Security Controller does not run any IKEv2
implementation (neither the NSFs), 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 Security
Controller.
Figure 4 describes the IKE-less case, when a data packet needs to be
protected in the path between the NSF A and NSF B:
1. The administrator establishes the flow-based security policies,
and 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 these entries in both NSF A and
NSF B IPsec databases (SPD and SAD). The following text
describes how this happens between two NSFs A and B:
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* The Security Controller chooses two random values as SPIs: for
example, SPIa1 for NSF A and SPIb1 for NSF B. These numbers
MUST NOT be in conflict with any IPsec SA in NSF A or NSF B.
It also generates fresh cryptographic material for the new
inbound/outbound IPsec SAs and their parameters and send
simultaneously the new inbound IPsec SA with SPIa1 and new
outbound IPsec SAs with SPIb1 to NSF A; and the new inbound
IPsec SA with SPIb1 and new outbound IPsec SAs with SPIa1 to
B, together with the corresponding IPsec policies.
* Once the Security Controller receives confirmation from NSF A
and NSF B, the controller knows that the IPsec SAs are
correctly installed and ready.
If some of the operations described above fails (e.g. the NSF A
reports an error when the Security Controller is trying to
install the SPD entry, the new inbound and outbound IPsec SAs)
the Security Controller must perform rollback operations by
deleting any new inbound or outbound SA and SPD entry that had
been successfully installed in any of the NSFs (e.g NSF B) and
stop the process (NOTE: the Security Controller may retry several
times before giving up). Other alternative to this operation is:
the Security Controller sends first the IPsec policies and new
inbound IPsec SAs to A and B and once it obtains a successful
confirmation of these operations from NSF A and NSF B, it
proceeds with installing to the new outbound IPsec SAs. However,
this may increase the latency to complete the process. As an
advantage, no traffic is sent over the network until the IPsec
SAs are completely operative. In any case other alternatives may
be possible. Finally, it is worth mentioning that the Security
Controller associates a lifetime to the new 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.
Instead of installing IPsec policies in the SPD and IPsec SAs in the
SAD in step 3 (proactive mode), it is also possible that the Security
Controller only installs the SPD entries in step 3 (reactive mode).
In such a case, when a data packet requires to be protected with
IPsec, the NSF that saw first the data packet will send a sadb-
acquire notification that informs the Security Controller that needs
SAD entries with the IPsec SAs to process the data packet. In such
as reactive mode, since IPsec policies are already installed in the
SPD, the Security Controller installs first the new IPsec SAs in NSF
A and B with the operations described in step 3 but without sending
any IPsec policies. Again, if some of the operations installing the
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new inbound/outbound IPsec SAs fail, the Security Controller stops
the process and performs a rollback operation by deleting any new
inbound/outbound SAs that had been successfully installed.
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),
for example, within an enterprise that needs to protect the traffic
between 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, 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) and providing VPN solutions for virtualized networks
(gateway-to-gateway).
In general (for IKE and IKE-less cases), this system has various
advantages:
1. It allows to create IPsec SAs among two NSFs, based only on the
application of 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.
2. Any NSF deployed in the system does not need manual
configuration, therefore allowing its deployment in an automated
manner.
7.2. Host-to-host or gateway-to-gateway under different Security
Controllers
It is also possible that two NSFs (i.e. NSF A and NSF B) 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.
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+-------------+ +-------------+
| | | |
Flow-based| Security |<=========>| Security <--Flow-based
Sec. Pol.--> Controller | (3) | Controller | Sec. Pol.
(1) | A | | B | (2)
+-------------+ +-------------+
| |
| (4) (4) |
V V
+--------------------+ +--------------------+
| NSF A |<=======>| NSF B |
|IKEv2/IPsec(SPD/PAD)| |IKEv2/IPsec(SPD/PAD)|
+--------------------+ (5) +--------------------+
Figure 5: Different Security Controllers in the IKE case.
Figure 5 describes IKE case when two 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 NSF A and NSF B, but the NSF B 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,
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.
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+--------------+ +--------------+
| | | |
Flow-based. ---> | | <---Flow-based
Prot. | Security |<===========>| Security |Sec.
Pol.(1)| Controller | (3) | Controller |Pol. (2)
| A | | B |
+--------------+ +--------------+
| |
| (4) (4) |
V V
+--------------+ (5) +--------------+
| NSF A |<==============>| NSF B |
|IPsec(SPD/SAD)| |IPsec(SPD/SAD)|
+--------------+ +--------------+
Figure 6: Different Security Controllers in the IKE-less case.
Figure 6 describes IKE-less case when two 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 NSF B
and NSF B MUST be protected. Nevertheless, it notices that NSF B
is under the control of another Security Controller B, 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 the 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. IANA Considerations
This document registers three URIs in the "ns" subregistry of the
IETF XML Registry [RFC3688]. Following the format in [RFC3688], the
following registrations are requested:
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URI: urn:ietf:params:xml:ns:yang:ietf-ipsec-common
Registrant Contact: The I2NSF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-ipsec-ike
Registrant Contact: The I2NSF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless
Registrant Contact: The I2NSF WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers three YANG modules in the "YANG Module Names"
registry [RFC6020]. Following the format in [RFC6020], the following
registrations are requested:
Name: ietf-ipsec-common
Namespace: urn:ietf:params:xml:ns:yang:ietf-ipsec-common
Prefix: ic
Reference: RFC XXXX
Name: ietf-ipsec-ike
Namespace: urn:ietf:params:xml:ns:yang:ietf-ipsec-ike
Prefix: ike
Reference: RFC XXXX
Name: ietf-ipsec-ikeless
Namespace: urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless
Prefix: ikeless
Reference: RFC XXXX
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, when NETCONF is used as southbound protocol between the
Security Controller and the NSFs, it is defined that TLS or SSH
security association MUST be established between both entities.
On the other hand, if encryption is mandatory for all traffic of a
NSF, its default policy MUST be to drop (DISCARD) packets to prevent
cleartext packet leaks. This default policy MUST be in the startup
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configuration datastore in the NSF before the NSF contacts with the
Security Controller. Moreover, the startup configuration datastore
MUST be pre-configured with the required ALLOW policies that allow to
communicate the NSF with the Security Controller once the NSF is
deployed. This pre-configuration step is not carried out by the
Security Controller but by some other entity before the NSF
deployment. In this manner, when the NSF starts/reboots, it will
always apply first the configuration in the startup configuration
before contacting the Security Controller.
Finally, we have divided this section in two parts in order to
analyze different security considerations for both cases: NSF with
IKEv2 (IKE case) and NSF without IKEv2 (IKE-less case). In general,
the Security Controller, as typically in the SDN paradigm, is a
target for different type of attacks. Thus, the Security Controller
is a key entity in the infrastructure and MUST be protected
accordingly. In particular, 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
case the attack occurs. The impact is different depending on the IKE
case or IKE-less case.
9.1. IKE case
In 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 MUST NOT 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
to return always the same value (i.e. all 0s) if a read operation is
carried out. If the attacker has access to the Security Controller
during the period of time that key material is generated, it might
have access to the key material. 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 MUST remove the PSK immediately
after generating and distributing it. Moreover, the PSK MUST have a
proper length (e.g. minimum 128 bit length) and strength. When
public/private keys are used, the Security Controller MAY generate
both public key and private key. In such a case, the Security
Controller MUST remove the associated private key immediately after
distributing them to the NSFs. Alternatively, the NSF could generate
the private key and export only the public key to the Security
Controller. If certificates are used, the NSF MAY generate the
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private key and exports the public key for certification to the
Security Controller. How the NSF generates these cryptographic
material (public key/private keys) and export the public key, or it
is instructed to do so, it is out of the scope of this document.
9.2. IKE-less case
In the IKE-less case, the Security Controller sends the IPsec SA
information to the NSF's SAD that includes the private session keys
required for integrity and encryption. The general recommendation is
that it MUST NOT store the keys after distributing them. Moreover,
the NSFs receiving private key material MUST NOT allow the reading of
these values by any other entity (including the Security Controller
itself) once they have been applied (i.e. write only operations) into
the NSFs. Nevertheless, if the attacker has access to the Security
Controller during the period of time that key material is generated,
it may obtain these values. In other words, the attacker might be
able to observe the IPsec traffic and decrypt, or even modify and re-
encrypt the traffic between peers.
9.3. YANG modules
The YANG module specified in this document defines a schema for data
that is designed to be accessed via network management protocols such
as NETCONF [RFC6241] or RESTCONF [RFC8040]. The lowest NETCONF layer
is the secure transport layer, and the mandatory-to-implement secure
transport is Secure Shell (SSH) [RFC6242]. The lowest RESTCONF layer
is HTTPS, and the mandatory-to-implement secure transport is TLS
[RFC8446].
The Network Configuration Access Control Model (NACM) [RFC8341]
provides the means to restrict access for particular NETCONF or
RESTCONF users to a preconfigured subset of all available NETCONF or
RESTCONF protocol operations and content.
There are a number of data nodes defined in these YANG modules that
are writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., edit-config)
to these data nodes without proper protection can have a negative
effect on network operations. These are the subtrees and data nodes
and their sensitivity/vulnerability:
The YANG modules describe configuration data for the IKE case (ietf-
ipsec-ike) and IKE-less case (ietf-ipsec-ikeless). There is a common
module (ietf-ipsec-common) used in both cases.
For the IKE case (ietf-ipsec-ike):
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/ipsec-ike: The entire container in this module is sensitive to
write operations. An attacker may add/modify the credentials
to be used for the authentication (e.g. to impersonate a NSF),
the trust root (e.g. changing the trusted CA certificates),
the cryptographic algorithms (allowing a downgrading attack),
the IPsec policies (e.g. by allowing leaking of data traffic by
changing to a allow policy), and in general changing the IKE SA
conditions and credentials between any NSF.
For the IKE-less case (ietf-ipsec-ikeless):
/ipsec-ikeless: The entire container in this module is
sensitive to write operations. An attacker may add/modify/
delete any IPsec policies (e.g. by allowing leaking of data
traffic by changing to a allow policy) in the /ipsec-ikeless/
spd container, and add/modify/delete any IPsec SAs between two
NSF by means of /ipsec-ikeless/sad container and, in general
changing any IPsec SAs and IPsec policies between any NSF.
Some of the readable data nodes in this YANG module may be considered
sensitive or vulnerable in some network environments. It is thus
important to control read access (e.g., via get, get-config, or
notification) to these data nodes. These are the subtrees and data
nodes and their sensitivity/vulnerability:
For the IKE case (ietf-ipsec-ike):
/ipsec-ike/pad: This container includes sensitive information
to read operations. This information should never be returned
to a client. For example, cryptographic material configured in
the NSFs: peer-authentication/pre-shared/secret and peer-
authentication/digital-signature/private-key are already
protected by the NACM extension "default-deny-all" in this
document.
For the IKE-less case (ietf-ipsec-ikeless):
/ipsec-ikeless/sad/ipsec-sa-config/esp-sa: This container
includes symmetric keys for the IPsec SAs. For example,
encryption/key contains a ESP encryption key value and
encryption/iv contains a initialization vector value.
Similarly, integrity/key has ESP integrity key value. Those
values must not be read by anyone and are protected by the NACM
extension "default-deny-all" in this document.
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10. Acknowledgements
Authors want to thank Paul Wouters, Valery Smyslov, Sowmini Varadhan,
David Carrel, Yoav Nir, Tero Kivinen, Martin Bjorklund, Graham
Bartlett, Sandeep Kampati, Linda Dunbar, Carlos J. Bernardos,
Alejandro Perez-Mendez, Alejandro Abad-Carrascosa, Ignacio Martinez
and Ruben Ricart for their valuable comments.
11. References
11.1. 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>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<https://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<https://www.rfc-editor.org/info/rfc6242>.
[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>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
[RFC8341] Bierman, A. and M. Bjorklund, "Network Configuration
Access Control Model", STD 91, RFC 8341,
DOI 10.17487/RFC8341, March 2018,
<https://www.rfc-editor.org/info/rfc8341>.
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[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
11.2. 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-terminology]
Hares, S., Strassner, J., Lopez, D., Xia, L., and H.
Birkholz, "Interface to Network Security Functions (I2NSF)
Terminology", draft-ietf-i2nsf-terminology-08 (work in
progress), July 2019.
[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.
[libreswan]
The Libreswan Project, "Libreswan VPN software", August
2019.
[netconf-vpn]
Stefan Wallin, "Tutorial: NETCONF and YANG", January 2014.
[ONF-OpenFlow]
ONF, "OpenFlow Switch Specification (Version 1.4.0)",
October 2013.
[ONF-SDN-Architecture]
"SDN Architecture", June 2014.
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[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>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[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>.
[RFC7426] Haleplidis, E., Ed., Pentikousis, K., Ed., Denazis, S.,
Hadi Salim, J., Meyer, D., and O. Koufopavlou, "Software-
Defined Networking (SDN): Layers and Architecture
Terminology", RFC 7426, DOI 10.17487/RFC7426, January
2015, <https://www.rfc-editor.org/info/rfc7426>.
[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>.
[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>.
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[RFC8512] Boucadair, M., Ed., Sivakumar, S., Jacquenet, C.,
Vinapamula, S., and Q. Wu, "A YANG Module for Network
Address Translation (NAT) and Network Prefix Translation
(NPT)", RFC 8512, DOI 10.17487/RFC8512, January 2019,
<https://www.rfc-editor.org/info/rfc8512>.
[strongswan]
CESNET, "StrongSwan: the OpenSource IPsec-based VPN
Solution", August 2019.
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Appendix A. Appendix A: Common YANG model for IKE and IKE-less cases
<CODE BEGINS> file "ietf-ipsec-common@2019-08-05.yang"
module ietf-ipsec-common {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-ipsec-common";
prefix "ipsec-common";
import ietf-inet-types { prefix inet; }
import ietf-yang-types { prefix yang; }
organization "IETF I2NSF Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/i2nsf/about/>
WG List: <mailto:i2nsf@ietf.org>
Author: Rafael Marin-Lopez
<mailto:rafa@um.es>
Author: Gabriel Lopez-Millan
<mailto:gabilm@um.es>
Author: Fernando Pereniguez-Garcia
<mailto:fernando.pereniguez@cud.upct.es>
";
description
"Common Data model for the IKE and IKE-less cases
defined by the SDN-based IPsec flow protection service.
Copyright (c) 2019 IETF Trust and the persons
identified as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with
or without modification, is permitted pursuant to, and
subject to the license terms contained in, the
Simplified BSD License set forth in Section 4.c of the
IETF Trust's Legal Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX;;
see the RFC itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
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'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this
document are to be interpreted as described in BCP 14
(RFC 2119) (RFC 8174) when, and only when, they appear
in all capitals, as shown here.";
revision "2019-08-05" {
description "Revision 06";
reference "RFC XXXX: YANG Groupings and typedef
for IKE and IKE-less case";
}
typedef encryption-algorithm-type {
type uint16;
description
"The encryption algorithm is specified with a 16-bit
number extracted from IANA Registry. The acceptable
values MUST follow the requirement levels for
encryption algorithms for ESP and IKEv2.";
reference
"IANA Registry- Transform Type 1 - Encryption
Algorithm Transform IDs. RFC 8221 - Cryptographic
Algorithm Implementation Requirements and Usage
Guidance for Encapsulating Security Payload (ESP)
and Authentication Header (AH) and RFC 8247 -
Algorithm Implementation Requirements and Usage
Guidance for the Internet Key Exchange Protocol
Version 2 (IKEv2).";
}
typedef integrity-algorithm-type {
type uint16;
description
"The integrity algorithm is specified with a 16-bit
number extracted from IANA Registry.
The acceptable values MUST follow the requirement
levels for encryption algorithms for ESP and IKEv2.";
reference
"IANA Registry- Transform Type 3 - Integrity
Algorithm Transform IDs. RFC 8221 - Cryptographic
Algorithm Implementation Requirements and Usage
Guidance for Encapsulating Security Payload (ESP)
and Authentication Header (AH) and RFC 8247 -
Algorithm Implementation Requirements and Usage
Guidance for the Internet Key Exchange Protocol
Version 2 (IKEv2).";
}
typedef ipsec-mode {
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type enumeration {
enum transport {
description
"IPsec transport mode. No Network Address
Translation (NAT) support.";
}
enum tunnel {
description "IPsec tunnel mode.";
}
}
description
"Type definition of IPsec mode: transport or
tunnel.";
reference
"Section 3.2 in RFC 4301.";
}
typedef esp-encap {
type enumeration {
enum espintcp {
description
"ESP in TCP encapsulation.";
reference
"RFC 8229 - TCP Encapsulation of IKE and
IPsec Packets.";
}
enum espintls {
description
"ESP in TCP encapsulation using TLS.";
reference
"RFC 8229 - TCP Encapsulation of IKE and
IPsec Packets.";
}
enum espinudp {
description
"ESP in UDP encapsulation.";
reference
"RFC 3948 - UDP Encapsulation of IPsec ESP
Packets.";
}
enum none {
description
"NOT ESP encapsulation.";
}
}
description
"Types of ESP encapsulation when Network Address
Translation (NAT) is present between two NSFs.";
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reference
"RFC 8229 - TCP Encapsulation of IKE and IPsec
Packets and RFC 3948 - UDP Encapsulation of IPsec
ESP Packets.";
}
typedef ipsec-protocol-parameters {
type enumeration {
enum esp { description "IPsec ESP protocol."; }
}
description
"Only the Encapsulation Security Protocol (ESP) is
supported but it could be extended in the future.";
reference
"RFC 4303- IP Encapsulating Security Payload
(ESP).";
}
typedef lifetime-action {
type enumeration {
enum terminate-clear {
description
"Terminates the IPsec SA and allows the
packets through.";
}
enum terminate-hold {
description
"Terminates the IPsec SA and drops the
packets.";
}
enum replace {
description
"Replaces the IPsec SA with a new one:
rekey. ";
}
}
description
"When the lifetime of an IPsec SA expires an action
needs to be performed over the IPsec SA that
reached the lifetime. There are three posible
options: terminate-clear, terminate-hold and
replace.";
reference
"Section 4.5 in RFC 4301.";
}
typedef ipsec-traffic-direction {
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type enumeration {
enum inbound {
description "Inbound traffic.";
}
enum outbound {
description "Outbound traffic.";
}
}
description
"IPsec traffic direction is defined in two
directions: inbound and outbound. From a NSF
perspective inbound means the traffic that enters
the NSF and outbound is the traffic that is sent
from the NSF.";
reference
"Section 5 in RFC 4301.";
}
typedef ipsec-spd-action {
type enumeration {
enum protect {
description
"PROTECT the traffic with IPsec.";
}
enum bypass {
description
"BYPASS the traffic. The packet is forwarded
without IPsec protection.";
}
enum discard {
description
"DISCARD the traffic. The IP packet is
discarded.";
}
}
description
"The action when traffic matches an IPsec security
policy. According to RFC 4301 there are three
possible values: BYPASS, PROTECT AND DISCARD";
reference
"Section 4.4.1 in RFC 4301.";
}
typedef ipsec-inner-protocol {
type union {
type uint8;
type enumeration {
enum any {
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value 256;
description
"Any IP protocol number value.";
}
}
}
default any;
description
"IPsec protection can be applied to specific IP
traffic and layer 4 traffic (TCP, UDP, SCTP, etc.)
or ANY protocol in the IP packet payload. We
specify the IP protocol number with an uint8 or
ANY defining an enumerate with value 256 to
indicate the protocol number.";
reference
"Section 4.4.1.1 in RFC 4301.
IANA Registry - Protocol Numbers.";
}
grouping encap {
description
"This group of nodes allows to define the type of
encapsulation in case NAT traversal is
required and port information.";
leaf espencap {
type esp-encap;
description
"ESP in TCP, ESP in UDP or ESP in TLS.";
}
leaf sport {
type inet:port-number;
default 4500;
description
"Encapsulation source port.";
}
leaf dport {
type inet:port-number;
default 4500;
description
"Encapsulation destination port.";
}
leaf-list oaddr {
type inet:ip-address;
description
"If required, this is the original address that
was used before NAT was applied over the Packet.
";
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}
reference
"RFC 3947 and RFC 8229.";
}
grouping lifetime {
description
"Different lifetime values limited to an IPsec SA.";
leaf time {
type uint32;
default 0;
description
"Time in seconds since the IPsec SA was added.
For example, if this value is 180 seconds it
means the IPsec SA expires in 180 seconds since
it was added. The value 0 implies infinite.";
}
leaf bytes {
type uint32;
default 0;
description
"If the IPsec SA processes the number of bytes
expressed in this leaf, the IPsec SA expires and
should be rekeyed. The value 0 implies
infinite.";
}
leaf packets {
type uint32;
default 0;
description
"If the IPsec SA processes the number of packets
expressed in this leaf, the IPsec SA expires and
should be rekeyed. The value 0 implies
infinite.";
}
leaf idle {
type uint32;
default 0;
description
"When a NSF stores an IPsec SA, it
consumes system resources. In an idle NSF this
is a waste of resources. If the IPsec SA is idle
during this number of seconds the IPsec SA
should be removed. The value 0 implies
infinite.";
}
reference
"Section 4.4.2.1 in RFC 4301.";
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}
grouping port-range {
description
"This grouping defines a port range, such as
expressed in RFC 4301. For example: 1500 (Start
Port Number)-1600 (End Port Number). A port range
is used in the Traffic Selector.";
leaf start {
type inet:port-number;
description
"Start port number.";
}
leaf end {
type inet:port-number;
description
"End port number.";
}
reference "Section 4.4.1.2 in RFC 4301.";
}
grouping tunnel-grouping {
description
"The parameters required to define the IP tunnel
endpoints when IPsec SA requires tunnel mode. The
tunnel is defined by two endpoints: the local IP
address and the remote IP address.";
leaf local {
type inet:ip-address;
mandatory true;
description
"Local IP address' tunnel endpoint.";
}
leaf remote {
type inet:ip-address;
mandatory true;
description
"Remote IP address' tunnel endpoint.";
}
leaf df-bit {
type enumeration {
enum clear {
description
"Disable the DF (Don't Fragment) bit
from the outer header. This is the
default value.";
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}
enum set {
description
"Enable the DF bit in the outer header.";
}
enum copy {
description
"Copy the DF bit to the outer header.";
}
}
default clear;
description
"Allow configuring the DF bit when encapsulating
tunnel mode IPsec traffic. RFC 4301 describes
three options to handle the DF bit during
tunnel encapsulation: clear, set and copy from
the inner IP header.";
reference
"Section 8.1 in RFC 4301.";
}
leaf bypass-dscp {
type boolean;
default true;
description
"If DSCP (Differentiated Services Code Point)
values in the inner header have to be used to
select one IPsec SA among several that match
the traffic selectors for an outbound packet";
reference
"Section 4.4.2.1. in RFC 4301.";
}
leaf dscp-mapping {
type yang:hex-string;
description
"DSCP values allowed for packets carried over
this IPsec SA.";
reference
"Section 4.4.2.1. in RFC 4301.";
}
leaf ecn {
type boolean;
default false;
description
"Explicit Congestion Notification (ECN). If true
copy CE bits to inner header.";
reference
"Section 5.1.2 and Annex C in RFC 4301.";
}
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}
grouping selector-grouping {
description
"This grouping contains the definition of a Traffic
Selector, which is used in the IPsec policies and
IPsec SAs.";
leaf local-subnet {
type inet:ip-prefix;
mandatory true;
description
"Local IP address subnet.";
}
leaf remote-subnet {
type inet:ip-prefix;
mandatory true;
description
"Remote IP address subnet.";
}
leaf inner-protocol {
type ipsec-inner-protocol;
default any;
description
"Inner Protocol that is going to be
protected with IPsec.";
}
list local-ports {
key "start end";
uses port-range;
description
"List of local ports. When the inner
protocol is ICMP this 16 bit value represents
code and type.";
}
list remote-ports {
key "start end";
uses port-range;
description
"List of remote ports. When the upper layer
protocol is ICMP this 16 bit value represents
code and type.";
}
reference
"Section 4.4.1.2 in RFC 4301.";
}
grouping ipsec-policy-grouping {
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description
"Holds configuration information for an IPsec SPD
entry.";
leaf anti-replay-window {
type uint64;
default 32;
description
"A 64-bit counter used to determine whether an
inbound ESP packet is a replay.";
reference
"Section 4.4.2.1 in RFC 4301.";
}
container traffic-selector {
description
"Packets are selected for
processing actions based on the IP and inner
protocol header information, selectors,
matched against entries in the SPD.";
uses selector-grouping;
reference
"Section 4.4.4.1 in RFC 4301.";
}
container processing-info {
description
"SPD processing. If the required processing
action is protect, it contains the required
information to process the packet.";
leaf action {
type ipsec-spd-action;
default discard;
description
"If bypass or discard, container
ipsec-sa-cfg is empty.";
}
container ipsec-sa-cfg {
when "../action = 'protect'";
description
"IPSec SA configuration included in the SPD
entry.";
leaf pfp-flag {
type boolean;
default false;
description
"Each selector has a Populate From
Packet (PFP) flag. If asserted for a
given selector X, the flag indicates
that the IPSec SA to be created should
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take its value (local IP address,
remote IP address, Next Layer
Protocol, etc.) for X from the value
in the packet. Otherwise, the IPsec SA
should take its value(s) for X from
the value(s) in the SPD entry.";
}
leaf ext-seq-num {
type boolean;
default false;
description
"True if this IPsec SA is using extended
sequence numbers. True 64 bit counter,
False 32 bit.";
}
leaf seq-overflow {
type boolean;
default false;
description
"The flag indicating whether
overflow of the sequence number
counter should prevent transmission
of additional packets on the IPsec
SA (false) and, therefore needs to
be rekeyed, or whether rollover is
permitted (true). If Authenticated
Encryption with Associated Data
(AEAD) is used this flag MUST be
false.";
}
leaf stateful-frag-check {
type boolean;
default false;
description
"Indicates whether (true) or not (false)
stateful fragment checking applies to
the IPsec SA to be created.";
}
leaf mode {
type ipsec-mode;
default transport;
description
"IPsec SA has to be processed in
transport or tunnel mode.";
}
leaf protocol-parameters {
type ipsec-protocol-parameters;
default esp;
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description
"Security protocol of the IPsec SA:
Only ESP is supported but it could be
extended in the future.";
}
container esp-algorithms {
when "../protocol-parameters = 'esp'";
description
"Configuration of Encapsulating
Security Payload (ESP) parameters and
algorithms.";
leaf-list integrity {
type integrity-algorithm-type;
default 0;
ordered-by user;
description
"Configuration of ESP authentication
based on the specified integrity
algorithm. With AEAD algorithms,
the integrity node is not
used.";
reference
"Section 3.2 in RFC 4303.";
}
leaf-list encryption {
type encryption-algorithm-type;
default 20;
ordered-by user;
description
"Configuration of ESP encryption
algorithms. The default value is
20 (ENCR_AES_GCM_16).";
reference
"Section 3.2 in RFC 4303.";
}
leaf tfc-pad {
type boolean;
default false;
description
"If Traffic Flow Confidentiality
(TFC) padding for ESP encryption
can be used (true) or not (false)";
reference
"Section 2.7 in RFC 4303.";
}
reference
"RFC 4303.";
}
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container tunnel {
when "../mode = 'tunnel'";
uses tunnel-grouping;
description
"IPsec tunnel endpoints definition.";
}
}
reference
"Section 4.4.1.2 in RFC 4301.";
}
container spd-mark {
description
"The Mark to set for the IPsec SA of this
connection. This option is only available
on linux NETKEY/XFRM kernels. It can be
used with iptables to create custom
iptables rules using CONNMARK. It can also
be used with Virtual Tunnel Interfaces
(VTI) to direct marked traffic to
specific vtiXX devices.";
leaf mark {
type uint32;
default 0;
description
"Mark used to match XFRM policies and
states.";
}
leaf mask {
type yang:hex-string;
default 00:00:00:00;
description
"Mask used to match XFRM policies and
states.";
}
}
}
}
<CODE ENDS>
Appendix B. Appendix B: YANG model for IKE case
<CODE BEGINS> file "ietf-ipsec-ike@2019-08-05.yang"
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module ietf-ipsec-ike {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-ipsec-ike";
prefix "ike";
import ietf-inet-types { prefix inet; }
import ietf-yang-types { prefix yang; }
import ietf-crypto-types {
prefix ct;
reference
"draft-ietf-netconf-crypto-types-10:
Common YANG Data Types for Cryptography.";
}
import ietf-ipsec-common {
prefix ic;
reference
"RFC XXXX: module ietf-ipsec-common, revision
2019-08-05.";
}
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control
Model.";
}
organization "IETF I2NSF Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/i2nsf/about/>
WG List: <mailto:i2nsf@ietf.org>
Author: Rafael Marin-Lopez
<mailto:rafa@um.es>
Author: Gabriel Lopez-Millan
<mailto:gabilm@um.es>
Author: Fernando Pereniguez-Garcia
<mailto:fernando.pereniguez@cud.upct.es>
";
description
"This module contains IPSec IKE case model for the SDN-based
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IPsec flow protection service. An NSF will implement this
module.
Copyright (c) 2019 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this
document are to be interpreted as described in BCP 14
(RFC 2119) (RFC 8174) when, and only when, they appear
in all capitals, as shown here.";
revision "2019-08-05" {
description "Revision 6";
reference
"RFC XXXX: YANG model for IKE case.";
}
typedef ike-spi {
type uint64 { range "0..max"; }
description
"Security Parameter Index (SPI)'s IKE SA.";
reference
"Section 2.6 in RFC 7296.";
}
typedef autostartup-type {
type enumeration {
enum add {
description
"IKE/IPsec configuration is only loaded into
IKE implementation but IKE/IPsec SA is not
started.";
}
enum on-demand {
description
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"IKE/IPsec configuration is loaded
into IKE implementation. The IPsec policies
are transferred to the NSF's kernel but the
IPsec SAs are not established immediately.
The IKE implementation will negotiate the
IPsec SAs when the NSF's kernel requests it
(i.e. through an ACQUIRE notification).";
}
enum start {
description "IKE/IPsec configuration is loaded
and transferred to the NSF's kernel, and the
IKEv2 based IPsec SAs are established
immediately without waiting any packet.";
}
}
description
"Different policies to set IPsec SA configuration
into NSF's kernel when IKEv2 implementation has
started.";
}
typedef pfs-group {
type uint16;
description
"DH groups for IKE and IPsec SA rekey.";
reference
"Section 3.3.2 in RFC 7296. Transform Type 4 -
Diffie-Hellman Group Transform IDs in IANA Registry
- Internet Key Exchange Version 2 (IKEv2)
Parameters.";
}
typedef auth-protocol-type {
type enumeration {
enum ikev2 {
value 2;
description
"IKEv2 authentication protocol. It is the
only defined right now. An enum is used for
further extensibility.";
}
}
description
"IKE authentication protocol version specified in the
Peer Authorization Database (PAD). It is defined as
enumerate to allow new IKE versions in the
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future.";
reference
"RFC 7296.";
}
typedef auth-method-type {
type enumeration {
enum pre-shared {
description
"Select pre-shared key as the
authentication method.";
reference
"RFC 7296.";
}
enum eap {
description
"Select EAP as the authentication method.";
reference
"RFC 7296.";
}
enum digital-signature {
description
"Select digital signature method.";
reference
"RFC 7296 and RFC 7427.";
}
enum null {
description
"Null authentication.";
reference
"RFC 7619.";
}
}
description
"Peer authentication method specified in the Peer
Authorization Database (PAD).";
}
container ipsec-ike {
description
"IKE configuration for a NSF. It includes PAD
parameters, IKE connections information and state
data.";
container pad {
description
"Configuration of Peer Authorization Database
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(PAD). The PAD contains information about IKE
peer (local and remote). Therefore, the Security
Controller also stores authentication
information for this NSF and can include
several entries for the local NSF not only
remote peers. Storing local and remote
information makes possible to specify that this
NSF with identity A will use some particular
authentication with remote NSF with identity B
and what are the authentication mechanisms
allowed to B.";
list pad-entry {
key "name";
ordered-by user;
description
"Peer Authorization Database (PAD) entry. It
is a list of PAD entries ordered by the
Security Controller.";
leaf name {
type string;
description
"PAD unique name to identify this
entry.";
}
choice identity {
mandatory true;
description
"A particular IKE peer will be
identified by one of these identities.
This peer can be a remote peer or local
peer (this NSF).";
reference
"Section 4.4.3.1 in RFC 4301.";
case ipv4-address{
leaf ipv4-address {
type inet:ipv4-address;
description
"Specifies the identity as a
single four (4) octet.";
}
}
case ipv6-address{
leaf ipv6-address {
type inet:ipv6-address;
description
"Specifies the identity as a
single sixteen (16) octet IPv6
address. An example is
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2001:DB8:0:0:8:800:200C:417A.";
}
}
case fqdn-string {
leaf fqdn-string {
type inet:domain-name;
description
"Specifies the identity as a
Fully-QualifiedDomain Name
(FQDN) string. An example is:
example.com. The string MUST
NOT contain any terminators
(e.g., NULL, CR, etc.).";
}
}
case rfc822-address-string {
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.).";
reference
"RFC 822.";
}
}
case dnx509 {
leaf dnx509 {
type string;
description
"Specifies the identity as a
ASN.1 X.500 Distinguished
Name. An example is
C=US,O=Example
Organisation,CN=John Smith.";
reference
"RFC 2247.";
}
}
case gnx509 {
leaf gnx509 {
type string;
description
"ASN.1 X.509 GeneralName. RFC
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3280.";
}
}
case id-key {
leaf id-key {
type string;
description
"Opaque octet stream that may be
used to pass vendor-specific
information for proprietary
types of identification.";
reference
"Section 3.5 in RFC 7296.";
}
}
case id-null {
leaf id-null {
type empty;
description
"ID_NULL identification used
when IKE identification payload
is not used." ;
reference
"RFC 7619.";
}
}
}
leaf auth-protocol {
type auth-protocol-type;
default ikev2;
description
"Only IKEv2 is supported right now but
other authentication protocols may be
supported in the future.";
}
container peer-authentication {
description
"This container allows the Security
Controller to configure the
authentication method (pre-shared key,
eap, digitial-signature, null) that
will use a particular peer and the
credentials, which will depend on the
selected authentication method.";
leaf auth-method {
type auth-method-type;
default pre-shared;
description
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"Type of authentication method
(pre-shared, eap, digital signature,
null).";
reference
"Section 2.15 in RFC 7296.";
}
container eap-method {
when "../auth-method = 'eap'";
leaf eap-type {
type uint8;
mandatory true;
description
"EAP method type. This
information provides the
particular EAP method to be
used. Depending on the EAP
method, pre-shared keys or
certificates may be used.";
}
description
"EAP method description used when
authentication method is 'eap'.";
reference
"Section 2.16 in RFC 7296.";
}
container pre-shared {
when
"../auth-method[.='pre-shared' or
.='eap']";
leaf secret {
nacm:default-deny-all;
type yang:hex-string;
description
"Pre-shared secret value. The
NSF has to prevent read access
to this value for security
reasons.";
}
description
"Shared secret value for PSK or
EAP method authentication based on
PSK.";
}
container digital-signature {
when
"../auth-method[.='digital-signature'
or .='eap']";
leaf ds-algorithm {
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type uint8;
description
"The digital signature
algorithm is specified with a
value extracted from the IANA
Registry. Depending on the
algorithm, the following leafs
must contain information. For
example if digital signature
involves a certificate then leaf
'cert-data' and 'private-key'
will contain this information.";
reference
"IKEv2 Authentication Method -
IANA Registry - Internet Key
Exchange Version 2 (IKEv2)
Parameters.";
}
choice public-key {
mandatory true;
leaf raw-public-key {
type binary;
description
"A binary that contains the
value of the public key. The
interpretation of the content
is defined by the digital
signature algorithm. For
example, an RSA key is
represented as RSAPublicKey as
defined in RFC 8017, and an
Elliptic Curve Cryptography
(ECC) key is represented
using the 'publicKey'
described in RFC 5915.";
reference
"RFC XXX: Common YANG Data
Types for Cryptography.";
}
leaf cert-data {
type ct:x509;
description
"X.509 certificate data -
PEM4.";
reference
"RFC XXX: Common YANG Data
Types for Cryptography.";
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}
description
"If the Security Controller
knows that the NSF
already owns a private key
associated to this public key
(the NSF generated the pair
public key/private key out of
band), it will only configure
one of the leaf of this
choice. The NSF, based on
the public key value can know
the private key to be used.";
}
leaf private-key {
nacm:default-deny-all;
type binary;
description
"A binary that contains the
value of the private key. The
interpretation of the content
is defined by the digital
signature algorithm. For
example, an RSA key is
represented as RSAPrivateKey as
defined in RFC 8017, and an
Elliptic Curve Cryptography
(ECC) key is represented as
ECPrivateKey as defined in RFC
5915.";
reference
"RFC XXX: Common YANG Data
Types for Cryptography.";
}
leaf-list ca-data {
type ct:x509;
description
"List of trusted Certification
Authorities (CA) certificates
encoded using ASN.1
distinguished encoding rules
(DER).";
reference
"RFC XXX: Common YANG Data
Types for Cryptography.";
}
leaf crl-data {
type ct:crl;
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description
"A CertificateList structure, as
specified in RFC 5280,
encoded using ASN.1
distinguished encoding rules
(DER),as specified in ITU-T
X.690.";
reference
"RFC XXX: Common YANG Data Types
for Cryptography.";
}
leaf crl-uri {
type inet:uri;
description
"X.509 CRL certificate URI.";
}
leaf oscp-uri {
type inet:uri;
description
"OCSP URI.";
}
description
"Digital Signature container.";
} /*container digital-signature*/
} /*container peer-authentication*/
}
}
list conn-entry {
key "name";
description
"IKE peer connection information. This list
contains the IKE connection for this peer
with other peers. This will be translated in
real time by IKE Security Associations
established with these nodes.";
leaf name {
type string;
mandatory true;
description
"Identifier for this connection
entry.";
}
leaf autostartup {
type autostartup-type;
default add;
description
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"By-default: Only add configuration
without starting the security
association.";
}
leaf initial-contact {
type boolean;
default false;
description
"The goal of this value is to deactivate the
usage of INITIAL_CONTACT notification
(true). If this flag remains to false it
means the usage of the INITIAL_CONTACT
notification will depend on the IKEv2
implementation.";
}
leaf version {
type auth-protocol-type;
default ikev2;
description
"IKE version. Only version 2 is supported
so far.";
}
leaf fragmentation {
type boolean;
default false;
description
"Whether or not to enable IKE
fragmentation as per RFC 7383 (true or
false).";
reference
"RFC 7383.";
}
container ike-sa-lifetime-soft {
description
"IKE SA lifetime soft. Two lifetime values
can be configured: either rekey time of the
IKE SA or reauth time of the IKE SA. When
the rekey lifetime expires a rekey of the
IKE SA starts. When reauth lifetime
expires a IKE SA reauthentication starts.";
leaf rekey-time {
type uint32;
default 0;
description
"Time in seconds between each IKE SA
rekey.The value 0 means infinite.";
}
leaf reauth-time {
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type uint32;
default 0;
description
"Time in seconds between each IKE SA
reauthentication. The value 0 means
infinite.";
}
reference
"Section 2.8 in RFC 7296.";
}
container ike-sa-lifetime-hard {
description
"Hard IKE SA lifetime. When this
time is reached the IKE SA is removed.";
leaf over-time {
type uint32;
default 0;
description
"Time in seconds before the IKE SA is
removed. The value 0 means infinite.";
}
reference
"RFC 7296.";
}
leaf-list authalg {
type ic:integrity-algorithm-type;
default 12;
ordered-by user;
description
"Authentication algorithm for establishing
the IKE SA. This list is ordered following
from the higher priority to lower priority.
First node of the list will be the algorithm
with higher priority. If this list is empty
the default integrity algorithm value assumed
is NONE.";
}
leaf-list encalg {
type ic:encryption-algorithm-type;
default 12;
ordered-by user;
description
"Encryption or AEAD algorithm for the IKE
SAs. This list is ordered following
from the higher priority to lower priority.
First node of the list will be the algorithm
with higher priority. If this list is empty
the default encryption value assumed is
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NULL.";
}
leaf dh-group {
type pfs-group;
default 14;
description
"Group number for Diffie-Hellman
Exponentiation used during IKE_SA_INIT
for the IKE SA key exchange.";
}
leaf half-open-ike-sa-timer {
type uint32;
description
"Set the half-open IKE SA timeout
duration.";
reference
"Section 2 in RFC 7296.";
}
leaf half-open-ike-sa-cookie-threshold {
type uint32;
description
"Number of half-open IKE SAs that activate
the cookie mechanism." ;
reference
"Section 2.6 in RFC 7296.";
}
container local {
leaf local-pad-entry-name {
type string;
description
"Local peer authentication information.
This node points to a specific entry in
the PAD where the authorization
information about this particular local
peer is stored. It MUST match a
pad-entry-name.";
}
description
"Local peer authentication information.";
}
container remote {
leaf remote-pad-entry-name {
type string;
description
"Remote peer authentication information.
This node points to a specific entry in
the PAD where the authorization
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information about this particular
remote peer is stored. It MUST match a
pad-entry-name.";
}
description
"Remote peer authentication information.";
}
container encapsulation-type
{
uses ic:encap;
description
"This container carries configuration
information about the source and destination
ports of encapsulation that IKE should use
and the type of encapsulation that
should use when NAT traversal is required.
However, this is just a best effort since
the IKE implementation may need to use a
different encapsulation as
described in RFC 8229.";
reference
"RFC 8229.";
}
container spd {
description
"Configuration of the Security Policy
Database (SPD). This main information is
placed in the grouping
ipsec-policy-grouping.";
list spd-entry {
key "name";
ordered-by user;
leaf name {
type string;
mandatory true;
description
"SPD entry unique name to identify
the IPsec policy.";
}
container ipsec-policy-config {
description
"This container carries the
configuration of a IPsec policy.";
uses ic:ipsec-policy-grouping;
}
description
"List of entries which will constitute
the representation of the SPD. Since we
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have IKE in this case, it is only
required to send a IPsec policy from
this NSF where 'local' is this NSF and
'remote' the other NSF. The IKE
implementation will install IPsec
policies in the NSF's kernel in both
directions (inbound and outbound) and
their corresponding IPsec SAs based on
the information in this SPD entry.";
}
reference
"Section 2.9 in RFC 7296.";
}
container child-sa-info {
leaf-list pfs-groups {
type pfs-group;
default 0;
ordered-by user;
description
"If non-zero, it is required perfect
forward secrecy when requesting new
IPsec SA. The non-zero value is
the required group number. This list is
ordered following from the higher
priority to lower priority. First node
of the list will be the algorithm
with higher priority.";
}
container child-sa-lifetime-soft {
description
"Soft IPsec SA lifetime soft.
After the lifetime the action is
defined in this container
in the leaf action.";
uses ic:lifetime;
leaf action {
type ic:lifetime-action;
default replace;
description
"When the lifetime of an IPsec SA
expires an action needs to be
performed over the IPsec SA that
reached the lifetime. There are
three possible options:
terminate-clear, terminate-hold and
replace.";
reference
"Section 4.5 in RFC 4301 and Section 2.8
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in RFC 7296.";
}
}
container child-sa-lifetime-hard {
description
"IPsec SA lifetime hard. The action will
be to terminate the IPsec SA.";
uses ic:lifetime;
reference
"Section 2.8 in RFC 7296.";
}
description
"Specific information for IPsec SAs
SAs. It includes PFS group and IPsec SAs
rekey lifetimes.";
}
container state {
config false;
leaf initiator {
type boolean;
description
"It is acting as initiator for this
connection.";
}
leaf initiator-ikesa-spi {
type ike-spi;
description
"Initiator's IKE SA SPI.";
}
leaf responder-ikesa-spi {
type ike-spi;
description
"Responder's IKE SA SPI.";
}
leaf nat-local {
type boolean;
description
"True, if local endpoint is behind a
NAT.";
}
leaf nat-remote {
type boolean;
description
"True, if remote endpoint is behind
a NAT.";
}
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container encapsulation-type
{
uses ic:encap;
description
"This container provides information
about the source and destination
ports of encapsulation that IKE is
using, and the type of encapsulation
when NAT traversal is required.";
reference
"RFC 8229.";
}
leaf established {
type uint64;
description
"Seconds since this IKE SA has been
established.";
}
leaf current-rekey-time {
type uint64;
description
"Seconds before IKE SA must be rekeyed.";
}
leaf current-reauth-time {
type uint64;
description
"Seconds before IKE SA must be
re-authenticated.";
}
description
"IKE state data for a particular
connection.";
} /* ike-sa-state */
} /* ike-conn-entries */
container number-ike-sas {
config false;
leaf total {
type uint64;
description
"Total number of active IKE SAs.";
}
leaf half-open {
type uint64;
description
"Number of half-open active IKE SAs.";
}
leaf half-open-cookies {
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type uint64;
description
"Number of half open active IKE SAs with
cookie activated.";
}
description
"General information about the IKE SAs. In
particular, it provides the current number of
IKE SAs.";
}
} /* container ipsec-ike */
}
<CODE ENDS>
Appendix C. Appendix C: YANG model for IKE-less case
<CODE BEGINS> file "ietf-ipsec-ikeless@2019-08-05.yang"
module ietf-ipsec-ikeless {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless";
prefix "ikeless";
import ietf-yang-types { prefix yang; }
import ietf-ipsec-common {
prefix ic;
reference
"Common Data model for SDN-based IPSec
configuration.";
}
import ietf-netconf-acm {
prefix nacm;
reference
"RFC 8341: Network Configuration Access Control
Model.";
}
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organization "IETF I2NSF Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/i2nsf/about/>
WG List: <mailto:i2nsf@ietf.org>
Author: Rafael Marin-Lopez
<mailto:rafa@um.es>
Author: Gabriel Lopez-Millan
<mailto:gabilm@um.es>
Author: Fernando Pereniguez-Garcia
<mailto:fernando.pereniguez@cud.upct.es>
";
description
"Data model for IKE-less case in the SDN-base IPsec flow
protection service.
Copyright (c) 2019 IETF Trust and the persons
identified as authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with
or without modification, is permitted pursuant to, and
subject to the license terms contained in, the
Simplified BSD License set forth in Section 4.c of the
IETF Trust's Legal Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX;;
see the RFC itself for full legal notices.
The key words 'MUST', 'MUST NOT', 'REQUIRED', 'SHALL',
'SHALL NOT', 'SHOULD', 'SHOULD NOT', 'RECOMMENDED',
'NOT RECOMMENDED', 'MAY', and 'OPTIONAL' in this
document are to be interpreted as described in BCP 14
(RFC 2119) (RFC 8174) when, and only when, they appear
in all capitals, as shown here.";
revision "2019-08-05" {
description "Revision 06";
reference "RFC XXXX: YANG model for IKE case.";
}
container ipsec-ikeless {
description
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"Container for configuration of the IKE-less
case. The container contains two additional
containers: 'spd' and 'sad'. The first allows the
Security Controller to configure IPsec policies in
the Security Policy Database SPD, and the second
allows to configure IPsec Security Associations
(IPsec SAs) in the Security Association Database
(SAD).";
reference "RFC 4301.";
container spd {
description
"Configuration of the Security Policy Database
(SPD.)";
reference "Section 4.4.1.2 in RFC 4301.";
list spd-entry {
key "name";
ordered-by user;
leaf name {
type string;
mandatory true;
description
"SPD entry unique name to identify this
entry.";
}
leaf direction {
type ic:ipsec-traffic-direction;
description
"Inbound traffic or outbound
traffic. In the IKE-less case the
Security Controller needs to
specify the policy direction to be
applied in the NSF. In the IKE case
this direction does not need to be
specified since IKE
will determine the direction that
IPsec policy will require.";
}
leaf reqid {
type uint64;
default 0;
description
"This value allows to link this
IPsec policy with IPsec SAs with the
same reqid. It is only required in
the IKE-less model since, in the IKE
case this link is handled internally
by IKE.";
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}
container ipsec-policy-config {
description
"This container carries the
configuration of a IPsec policy.";
uses ic:ipsec-policy-grouping;
}
description
"The SPD is represented as a list of SPD
entries, where each SPD entry represents an
IPsec policy.";
} /*list spd-entry*/
} /*container spd*/
container sad {
description
"Configuration of the IPSec Security Association
Database (SAD)";
reference "Section 4.4.2.1 in RFC 4301.";
list sad-entry {
key "name";
ordered-by user;
leaf name {
type string;
description
"SAD entry unique name to identify this
entry.";
}
leaf reqid {
type uint64;
default 0;
description
"This value allows to link this
IPsec SA with an IPsec policy with
the same reqid.";
}
container ipsec-sa-config {
description
"This container allows configuring
details of an IPsec SA.";
leaf spi {
type uint32 { range "0..max"; }
mandatory true;
description
"Security Parameter Index (SPI)'s
IPsec SA.";
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}
leaf ext-seq-num {
type boolean;
default true;
description
"True if this IPsec SA is using
extended sequence numbers. True 64
bit counter, FALSE 32 bit.";
}
leaf seq-number-counter {
type uint64;
default 0;
description
"A 64-bit counter when this IPsec
SA is using Extended Sequence
Number or 32-bit counter when it
is not. It used to generate the
initial Sequence Number field
in ESP headers.";
}
leaf seq-overflow {
type boolean;
default false;
description
"The flag indicating whether
overflow of the sequence number
counter should prevent transmission
of additional packets on the IPsec
SA (false) and, therefore needs to
be rekeyed, or whether rollover is
permitted (true). If Authenticated
Encryption with Associated Data
(AEAD) is used this flag MUST BE
false.";
}
leaf anti-replay-window {
type uint32;
default 32;
description
"A 32-bit counter and a bit-map (or
equivalent) used to determine
whether an inbound ESP packet is a
replay. If set to 0 no anti-replay
mechanism is performed.";
}
container traffic-selector {
uses ic:selector-grouping;
description
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"The IPsec SA traffic selector.";
}
leaf protocol-parameters {
type ic:ipsec-protocol-parameters;
default esp;
description
"Security protocol of IPsec SA: Only
ESP so far.";
}
leaf mode {
type ic:ipsec-mode;
description
"Tunnel or transport mode.";
}
container esp-sa {
when "../protocol-parameters =
'esp'";
description
"In case the IPsec SA is
Encapsulation Security Payload
(ESP), it is required to specify
encryption and integrity
algorithms, and key material.";
container encryption {
description
"Configuration of encryption or
AEAD algorithm for IPSec
Encapsulation Security Payload
(ESP).";
leaf encryption-algorithm {
type ic:encryption-algorithm-type;
description
"Configuration of ESP
encryption. With AEAD
algorithms, the integrity
node is not used.";
}
leaf key {
nacm:default-deny-all;
type yang:hex-string;
description
"ESP encryption key value.";
}
leaf iv {
nacm:default-deny-all;
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type yang:hex-string;
description
"ESP encryption IV value.";
}
}
container integrity {
description
"Configuration of integrity for
IPSec Encapsulation Security
Payload (ESP). This container
allows to configure integrity
algorithm when no AEAD
algorithms are used, and
integrity is required.";
leaf integrity-algorithm {
type ic:integrity-algorithm-type;
description
"Message Authentication Code
(MAC) algorithm to provide
integrity in ESP.";
}
leaf key {
nacm:default-deny-all;
type yang:hex-string;
description
"ESP integrity key value.";
}
}
} /*container esp-sa*/
container sa-lifetime-hard {
description
"IPsec SA hard lifetime. The action
associated is terminate and
hold.";
uses ic:lifetime;
}
container sa-lifetime-soft {
description
"IPSec SA soft lifetime.";
uses ic:lifetime;
leaf action {
type ic:lifetime-action;
description
"Action lifetime:
terminate-clear,
terminate-hold or replace.";
}
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}
container tunnel {
when "../mode = 'tunnel'";
uses ic:tunnel-grouping;
description
"Endpoints of the IPsec tunnel.";
}
container encapsulation-type
{
uses ic:encap;
description
"This container carries
configuration information about
the source and destination ports
which will be used for ESP
encapsulation that ESP packets the
type of encapsulation when NAT
traversal is in place.";
}
} /*ipsec-sa-config*/
container ipsec-sa-state {
config false;
description
"Container describing IPsec SA state
data.";
container sa-lifetime-current {
uses ic:lifetime;
description
"SAD lifetime current.";
}
container replay-stats {
description
"State data about the anti-replay
window.";
leaf replay-window {
type uint64;
description
"Current state of the replay
window.";
}
leaf packet-dropped {
type uint64;
description
"Packets detected out of the
replay window and dropped
because they are replay
packets.";
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}
leaf failed {
type uint32;
description
"Number of packets detected out
of the replay window.";
}
leaf seq-number-counter {
type uint64;
description
"A 64-bit counter when this
IPsec SA is using Extended
Sequence Number or 32-bit
counter when it is not.
Current value of sequence
number.";
}
} /* container replay-stats*/
} /*ipsec-sa-state*/
description
"List of SAD entries that conforms the SAD.";
} /*list sad-entry*/
} /*container sad*/
}/*container ipsec-ikeless*/
/* Notifications */
notification sadb-acquire {
description
"An IPsec SA is required. The traffic-selector
container contains information about the IP packet
that triggers the acquire notification.";
leaf ipsec-policy-name {
type string;
mandatory true;
description
"It contains the SPD entry name (unique) of
the IPsec policy that hits the IP packet
required IPsec SA. It is assumed the
Security Controller will have a copy of the
information of this policy so it can
extract all the information with this
unique identifier. The type of IPsec SA is
defined in the policy so the Security
Controller can also know the type of IPsec
SA that must be generated.";
}
container traffic-selector {
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description
"The IP packet that triggered the acquire
and requires an IPsec SA. Specifically it
will contain the IP source/mask and IP
destination/mask; protocol (udp, tcp,
etc...); and source and destination
ports.";
uses ic:selector-grouping;
}
}
notification sadb-expire {
description "An IPsec SA expiration (soft or hard).";
leaf ipsec-sa-name {
type string;
mandatory true;
description
"It contains the SAD entry name (unique) of
the IPsec SA that has expired. It is assumed
the Security Controller will have a copy of the
IPsec SA information (except the cryptographic
material and state data) indexed by this name
(unique identifier) so it can know all the
information (crypto algorithms, etc.) about
the IPsec SA that has expired in order to
perform a rekey (soft lifetime) or delete it
(hard lifetime) with this unique identifier.";
}
leaf soft-lifetime-expire {
type boolean;
default true;
description
"If this value is true the lifetime expired is
soft. If it is false is hard.";
}
container lifetime-current {
description
"IPsec SA current lifetime. If
soft-lifetime-expired is true this container is
set with the lifetime information about current
soft lifetime.";
uses ic:lifetime;
}
}
notification sadb-seq-overflow {
description "Sequence overflow notification.";
leaf ipsec-sa-name {
type string;
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mandatory true;
description
"It contains the SAD entry name (unique) of
the IPsec SA that is about to have sequence
number overflow and rollover is not permitted.
It is assumed the Security Controller will have
a copy of the IPsec SA information (except the
cryptographic material and state data) indexed
by this name (unique identifier) so the it can
know all the information (crypto algorithms,
etc.) about the IPsec SA that has expired in
order to perform a rekey of the IPsec SA.";
}
}
notification sadb-bad-spi {
description
"Notify when the NSF receives a packet with an
incorrect SPI (i.e. not present in the SAD).";
leaf spi {
type uint32 { range "0..max"; }
mandatory true;
description
"SPI number contained in the erroneous IPsec
packet.";
}
}
}/*module ietf-ipsec*/
<CODE ENDS>
Appendix D. Example of IKE case, tunnel mode (gateway-to-gateway) with
X.509 certificate authentication.
This example shows a XML configuration file sent by the Security
Controller to establish a IPsec Security Association between two NSFs
in tunnel mode (gateway-to-gateway) with ESP, and authentication
based on X.509 certificates using IKEv2.
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Security Controller
|
/---- Southbound interface -----\
/ \
/ \
/ \
/ \
nsf_h1 nsf_h2
h1---- (:1/:100)===== IPsec_ESP_Tunnel_mode =====(:200/:1)-------h2
2001:DB8:1:/64 (2001:DB8:123:/64) 2001:DB8:2:/64
Figure 7: IKE case, tunnel mode , X.509 certicate authentication.
<ipsec-ike xmlns="urn:ietf:params:xml:ns:yang:ietf-ipsec-ike"
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
<pad>
<pad-entry>
<name>nsf_h1_pad</name>
<ipv6-address>2001:DB8:123::100</ipv6-address>
<peer-authentication>
<auth-method>digital-signature</auth-method>
<digital-signature>
<cert-data>base64encodedvalue==</cert-data>
<private-key>base64encodedvalue==</private-key>
<ca-data>base64encodedvalue==</ca-data>
</digital-signature>
</peer-authentication>
</pad-entry>
<pad-entry>
<name>nsf_h2_pad</name>
<ipv6-address>2001:DB8:123::200</ipv6-address>
<auth-protocol>ikev2</auth-protocol>
<peer-authentication>
<auth-method>digital-signature</auth-method>
<digital-signature>
<!-- RSA Digital Signature -->
<ds-algorithm>1</ds-algorithm>
<cert-data>base64encodedvalue==</cert-data>
<ca-data>base64encodedvalue==</ca-data>
</digital-signature>
</peer-authentication>
</pad-entry>
</pad>
<conn-entry>
<name>nsf_h1-nsf_h2</name>
<autostartup>start</autostartup>
<version>ikev2</version>
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<initial-contact>false</initial-contact>
<fragmentation>true</fragmentation>
<ike-sa-lifetime-soft>
<rekey-time>60</rekey-time>
<reauth-time>120</reauth-time>
</ike-sa-lifetime-soft>
<ike-sa-lifetime-hard>
<over-time>3600</over-time>
</ike-sa-lifetime-hard>
<authalg>7</authalg>
<!--AUTH_HMAC_SHA1_160-->
<encalg>3</encalg>
<!--ENCR_3DES -->
<dh-group>18</dh-group>
<!--8192-bit MODP Group-->
<half-open-ike-sa-timer>30</half-open-ike-sa-timer>
<half-open-ike-sa-cookie-threshold>
15
</half-open-ike-sa-cookie-threshold>
<local>
<local-pad-entry-name>nsf_h1_pad</local-pad-entry-name>
</local>
<remote>
<remote-pad-entry-name>nsf_h2_pad</remote-pad-entry-name>
</remote>
<spd>
<spd-entry>
<name>nsf_h1-nsf_h2</name>
<ipsec-policy-config>
<anti-replay-window>32</anti-replay-window>
<traffic-selector>
<local-subnet>2001:DB8:1::0/64</local-subnet>
<remote-subnet>2001:DB8:2::0/64</remote-subnet>
<inner-protocol>any</inner-protocol>
<local-ports>
<start>0</start>
<end>0</end>
</local-ports>
<remote-ports>
<start>0</start>
<end>0</end>
</remote-ports>
</traffic-selector>
<processing-info>
<action>protect</action>
<ipsec-sa-cfg>
<pfp-flag>false</pfp-flag>
<ext-seq-num>true</ext-seq-num>
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<seq-overflow>false</seq-overflow>
<stateful-frag-check>false</stateful-frag-check>
<mode>tunnel</mode>
<protocol-parameters>esp</protocol-parameters>
<esp-algorithms>
<!-- AUTH_HMAC_SHA1_96 -->
<integrity>2</integrity>
<!-- ENCR_AES_CBC -->
<encryption>12</encryption>
<tfc-pad>false</tfc-pad>
</esp-algorithms>
<tunnel>
<local>2001:DB8:123::100</local>
<remote>2001:DB8:123::200</remote>
<df-bit>clear</df-bit>
<bypass-dscp>true</bypass-dscp>
<ecn>false</ecn>
</tunnel>
</ipsec-sa-cfg>
</processing-info>
</ipsec-policy-config>
</spd-entry>
</spd>
<child-sa-info>
<!--8192-bit MODP Group -->
<pfs-groups>18</pfs-groups>
<child-sa-lifetime-soft>
<bytes>1000000</bytes>
<packets>1000</packets>
<time>30</time>
<idle>60</idle>
<action>replace</action>
</child-sa-lifetime-soft>
<child-sa-lifetime-hard>
<bytes>2000000</bytes>
<packets>2000</packets>
<time>60</time>
<idle>120</idle>
</child-sa-lifetime-hard>
</child-sa-info>
</conn-entry>
</ipsec-ike>
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Appendix E. Example of IKE-less case, transport mode (host-to-host).
This example shows a XML configuration file sent by the Security
Controller to establish a IPsec Security association between two NSFs
in transport mode (host-to-host) with ESP.
Security Controller
|
/---- Southbound interface -----\
/ \
/ \
/ \
/ \
nsf_h1 nsf_h2
(:100)===== IPsec_ESP_Transport_mode =====(:200)
(2001:DB8:123:/64)
Figure 8: IKE-less case, transport mode.
<ipsec-ikeless
xmlns="urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless"
xmlns:nc="urn:ietf:params:xml:ns:netconf:base:1.0">
<spd>
<spd-entry>
<name>
in/trans/2001:DB8:123::200/2001:DB8:123::100
</name>
<direction>inbound</direction>
<reqid>1</reqid>
<ipsec-policy-config>
<traffic-selector>
<local-subnet>2001:DB8:123::200/128</local-subnet>
<remote-subnet>2001:DB8:123::100/128</remote-subnet>
<inner-protocol>any</inner-protocol>
<local-ports>
<start>0</start>
<end>0</end>
</local-ports>
<remote-ports>
<start>0</start>
<end>0</end>
</remote-ports>
</traffic-selector>
<processing-info>
<action>protect</action>
<ipsec-sa-cfg>
<ext-seq-num>true</ext-seq-num>
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<seq-overflow>true</seq-overflow>
<mode>transport</mode>
<protocol-parameters>esp</protocol-parameters>
<esp-algorithms>
<!--AUTH_HMAC_SHA1_96-->
<integrity>2</integrity>
<!--ENCR_AES_CBC -->
<encryption>12</encryption>
</esp-algorithms>
</ipsec-sa-cfg>
</processing-info>
</ipsec-policy-config>
</spd-entry>
<spd-entry>
<name>out/trans/2001:DB8:123::100/2001:DB8:123::200</name>
<direction>outbound</direction>
<reqid>1</reqid>
<ipsec-policy-config>
<traffic-selector>
<local-subnet>2001:DB8:123::100/128</local-subnet>
<remote-subnet>2001:DB8:123::200/128</remote-subnet>
<inner-protocol>any</inner-protocol>
<local-ports>
<start>0</start>
<end>0</end>
</local-ports>
<remote-ports>
<start>0</start>
<end>0</end>
</remote-ports>
</traffic-selector>
<processing-info>
<action>protect</action>
<ipsec-sa-cfg>
<ext-seq-num>true</ext-seq-num>
<seq-overflow>true</seq-overflow>
<mode>transport</mode>
<protocol-parameters>esp</protocol-parameters>
<esp-algorithms>
<!-- AUTH_HMAC_SHA1_96 -->
<integrity>2</integrity>
<!-- ENCR_AES_CBC -->
<encryption>12</encryption>
</esp-algorithms>
</ipsec-sa-cfg>
</processing-info>
</ipsec-policy-config>
</spd-entry>
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</spd>
<sad>
<sad-entry>
<name>out/trans/2001:DB8:123::100/2001:DB8:123::200</name>
<reqid>1</reqid>
<ipsec-sa-config>
<spi>34501</spi>
<ext-seq-num>true</ext-seq-num>
<seq-number-counter>100</seq-number-counter>
<seq-overflow>true</seq-overflow>
<anti-replay-window>32</anti-replay-window>
<traffic-selector>
<local-subnet>2001:DB8:123::100/128</local-subnet>
<remote-subnet>2001:DB8:123::200/128</remote-subnet>
<inner-protocol>any</inner-protocol>
<local-ports>
<start>0</start>
<end>0</end>
</local-ports>
<remote-ports>
<start>0</start>
<end>0</end>
</remote-ports>
</traffic-selector>
<protocol-parameters>esp</protocol-parameters>
<mode>transport</mode>
<esp-sa>
<encryption>
<!-- //ENCR_AES_CBC -->
<encryption-algorithm>12</encryption-algorithm>
<key>01:23:45:67:89:AB:CE:DF</key>
<iv>01:23:45:67:89:AB:CE:DF</iv>
</encryption>
<integrity>
<!-- //AUTH_HMAC_SHA1_96 -->
<integrity-algorithm>2</integrity-algorithm>
<key>01:23:45:67:89:AB:CE:DF</key>
</integrity>
</esp-sa>
</ipsec-sa-config>
</sad-entry>
<sad-entry>
<name>in/trans/2001:DB8:123::200/2001:DB8:123::100</name>
<reqid>1</reqid>
<ipsec-sa-config>
<spi>34502</spi>
<ext-seq-num>true</ext-seq-num>
<seq-number-counter>100</seq-number-counter>
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<seq-overflow>true</seq-overflow>
<anti-replay-window>32</anti-replay-window>
<traffic-selector>
<local-subnet>2001:DB8:123::200/128</local-subnet>
<remote-subnet>2001:DB8:123::100/128</remote-subnet>
<inner-protocol>any</inner-protocol>
<local-ports>
<start>0</start>
<end>0</end>
</local-ports>
<remote-ports>
<start>0</start>
<end>0</end>
</remote-ports>
</traffic-selector>
<protocol-parameters>esp</protocol-parameters>
<mode>transport</mode>
<esp-sa>
<encryption>
<!-- //ENCR_AES_CBC -->
<encryption-algorithm>12</encryption-algorithm>
<key>01:23:45:67:89:AB:CE:DF</key>
<iv>01:23:45:67:89:AB:CE:DF</iv>
</encryption>
<integrity>
<!-- //AUTH_HMAC_SHA1_96 -->
<integrity-algorithm>2</integrity-algorithm>
<key>01:23:45:67:89:AB:CE:DF</key>
</integrity>
</esp-sa>
<sa-lifetime-hard>
<bytes>2000000</bytes>
<packets>2000</packets>
<time>60</time>
<idle>120</idle>
</sa-lifetime-hard>
<sa-lifetime-soft>
<bytes>1000000</bytes>
<packets>1000</packets>
<time>30</time>
<idle>60</idle>
<action>replace</action>
</sa-lifetime-soft>
</ipsec-sa-config>
</sad-entry>
</sad>
</ipsec-ikeless>
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Appendix F. Examples of notifications.
Below we show several XML files that represent different types of
notifications defined in the IKE-less YANG model, which are sent by
the NSF to the Security Controller. The notifications happen in the
IKE-less case.
<sadb-expire xmlns="urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless">
<ipsec-sa-name>in/trans/2001:DB8:123::200/2001:DB8:123::100
</ipsec-sa-name>
<soft-lifetime-expire>true</soft-lifetime-expire>
<lifetime-current>
<bytes>1000000</bytes>
<packets>1000</packets>
<time>30</time>
<idle>60</idle>
</lifetime-current>
</sadb-expire>
Figure 9: Example of sadb-expire notification.
<sadb-acquire xmlns="urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless">
<ipsec-policy-name>in/trans/2001:DB8:123::200/2001:DB8:123::100
</ipsec-policy-name>
<traffic-selector>
<local-subnet>2001:DB8:123::200/128</local-subnet>
<remote-subnet>2001:DB8:123::100/128</remote-subnet>
<inner-protocol>any</inner-protocol>
<local-ports>
<start>0</start>
<end>0</end>
</local-ports>
<remote-ports>
<start>0</start>
<end>0</end>
</remote-ports>
</traffic-selector>
</sadb-acquire>
Figure 10: Example of sadb-acquire notification.
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<sadb-seq-overflow
xmlns="urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless">
<ipsec-sa-name>in/trans/2001:DB8:123::200/2001:DB8:123::100
</ipsec-sa-name>
</sadb-seq-overflow>
Figure 11: Example of sadb-seq-overflow notification.
<sadb-bad-spi
xmlns="urn:ietf:params:xml:ns:yang:ietf-ipsec-ikeless">
<spi>666</spi>
</sadb-bad-spi>
Figure 12: Example of sadb-bad-spi notification.
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
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