draft-ietf-detnet-security-12.txt   draft-ietf-detnet-security-13.txt 
Internet Engineering Task Force E. Grossman, Ed. Internet Engineering Task Force E. Grossman, Ed.
Internet-Draft DOLBY Internet-Draft DOLBY
Intended status: Informational T. Mizrahi Intended status: Informational T. Mizrahi
Expires: April 5, 2021 HUAWEI Expires: June 14, 2021 HUAWEI
A. Hacker A. Hacker
MISTIQ MISTIQ
October 2, 2020 December 11, 2020
Deterministic Networking (DetNet) Security Considerations Deterministic Networking (DetNet) Security Considerations
draft-ietf-detnet-security-12 draft-ietf-detnet-security-13
Abstract Abstract
A DetNet (deterministic network) provides specific performance A DetNet (deterministic network) provides specific performance
guarantees to its data flows, such as extremely low data loss rates guarantees to its data flows, such as extremely low data loss rates
and bounded latency. As a result, securing a DetNet requires that in and bounded latency (including bounded latency variation, i.e.
addition to the best practice security measures taken for any "jitter"). As a result, securing a DetNet requires that in addition
mission-critical network, additional security measures may be needed to the best practice security measures taken for any mission-critical
to secure the intended operation of these novel service properties. network, additional security measures may be needed to secure the
intended operation of these novel service properties.
This document addresses DetNet-specific security considerations from This document addresses DetNet-specific security considerations from
the perspectives of both the DetNet system-level designer and the perspectives of both the DetNet system-level designer and
component designer. System considerations include a threat model, component designer. System considerations include a threat model,
taxonomy of relevant attacks, and associations of threats versus use taxonomy of relevant attacks, and associations of threats versus use
cases and service properties. Component-level considerations include cases and service properties. Component-level considerations include
ingress filtering and packet arrival time violation detection. This ingress filtering and packet arrival time violation detection.
document also addresses DetNet security considerations specific to
the IP and MPLS data plane technologies thereby complementing the This document also addresses security considerations specific to the
Security Considerations sections of the various DetNet Data Plane IP and MPLS data plane technologies, thereby complementing the
(and other) DetNet documents. Security Considerations sections of those documents.
Status of This Memo Status of This Memo
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This Internet-Draft will expire on June 14, 2021.
This Internet-Draft will expire on April 5, 2021.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Abbreviations and Terminology . . . . . . . . . . . . . . . . 6 2. Abbreviations and Terminology . . . . . . . . . . . . . . . . 6
3. Security Considerations for DetNet Component Design . . . . . 6 3. Security Considerations for DetNet Component Design . . . . . 7
3.1. Resource Allocation . . . . . . . . . . . . . . . . . . . 7 3.1. Resource Allocation . . . . . . . . . . . . . . . . . . . 7
3.2. Explicit Routes . . . . . . . . . . . . . . . . . . . . . 7 3.2. Explicit Routes . . . . . . . . . . . . . . . . . . . . . 8
3.3. Redundant Path Support . . . . . . . . . . . . . . . . . 8 3.3. Redundant Path Support . . . . . . . . . . . . . . . . . 8
3.4. Timing (or other) Violation Reporting . . . . . . . . . . 9 3.4. Timing (or other) Violation Reporting . . . . . . . . . . 9
4. DetNet Security Considerations Compared With DiffServ 4. DetNet Security Considerations Compared With DiffServ
Security Considerations . . . . . . . . . . . . . . . . . . . 9 Security Considerations . . . . . . . . . . . . . . . . . . . 10
5. Security Threats . . . . . . . . . . . . . . . . . . . . . . 10 5. Security Threats . . . . . . . . . . . . . . . . . . . . . . 11
5.1. Threat Model . . . . . . . . . . . . . . . . . . . . . . 11 5.1. Threat Model . . . . . . . . . . . . . . . . . . . . . . 11
5.2. Threat Analysis . . . . . . . . . . . . . . . . . . . . . 12 5.2. Threat Analysis . . . . . . . . . . . . . . . . . . . . . 12
5.2.1. Delay . . . . . . . . . . . . . . . . . . . . . . . . 12 5.2.1. Delay . . . . . . . . . . . . . . . . . . . . . . . . 12
5.2.2. DetNet Flow Modification or Spoofing . . . . . . . . 12 5.2.2. DetNet Flow Modification or Spoofing . . . . . . . . 12
5.2.3. Resource Segmentation (Inter-segment Attack) . . . . 12 5.2.3. Resource Segmentation (Inter-segment Attack) . . . . 12
5.2.4. Packet Replication and Elimination . . . . . . . . . 12 5.2.4. Packet Replication and Elimination . . . . . . . . . 13
5.2.4.1. Replication: Increased Attack Surface . . . . . . 12 5.2.4.1. Replication: Increased Attack Surface . . . . . . 13
5.2.4.2. Replication-related Header Manipulation . . . . . 12 5.2.4.2. Replication-related Header Manipulation . . . . . 13
5.2.5. Controller Plane . . . . . . . . . . . . . . . . . . 13 5.2.5. Controller Plane . . . . . . . . . . . . . . . . . . 14
5.2.5.1. Path Choice Manipulation . . . . . . . . . . . . 13 5.2.5.1. Path Choice Manipulation . . . . . . . . . . . . 14
5.2.5.2. Compromised Controller . . . . . . . . . . . . . 14 5.2.5.2. Compromised Controller . . . . . . . . . . . . . 14
5.2.6. Reconnaissance . . . . . . . . . . . . . . . . . . . 14 5.2.6. Reconnaissance . . . . . . . . . . . . . . . . . . . 14
5.2.7. Time Synchronization Mechanisms . . . . . . . . . . . 14 5.2.7. Time Synchronization Mechanisms . . . . . . . . . . . 15
5.3. Threat Summary . . . . . . . . . . . . . . . . . . . . . 14 5.3. Threat Summary . . . . . . . . . . . . . . . . . . . . . 15
6. Security Threat Impacts . . . . . . . . . . . . . . . . . . . 15 6. Security Threat Impacts . . . . . . . . . . . . . . . . . . . 16
6.1. Delay-Attacks . . . . . . . . . . . . . . . . . . . . . . 18 6.1. Delay-Attacks . . . . . . . . . . . . . . . . . . . . . . 19
6.1.1. Data Plane Delay Attacks . . . . . . . . . . . . . . 18 6.1.1. Data Plane Delay Attacks . . . . . . . . . . . . . . 19
6.1.2. Controller Plane Delay Attacks . . . . . . . . . . . 19 6.1.2. Controller Plane Delay Attacks . . . . . . . . . . . 20
6.2. Flow Modification and Spoofing . . . . . . . . . . . . . 19 6.2. Flow Modification and Spoofing . . . . . . . . . . . . . 20
6.2.1. Flow Modification . . . . . . . . . . . . . . . . . . 19 6.2.1. Flow Modification . . . . . . . . . . . . . . . . . . 20
6.2.2. Spoofing . . . . . . . . . . . . . . . . . . . . . . 19 6.2.2. Spoofing . . . . . . . . . . . . . . . . . . . . . . 20
6.2.2.1. Dataplane Spoofing . . . . . . . . . . . . . . . 19 6.2.2.1. Dataplane Spoofing . . . . . . . . . . . . . . . 20
6.2.2.2. Controller Plane Spoofing . . . . . . . . . . . . 20 6.2.2.2. Controller Plane Spoofing . . . . . . . . . . . . 21
6.3. Segmentation Attacks (injection) . . . . . . . . . . . . 20 6.3. Segmentation Attacks (injection) . . . . . . . . . . . . 21
6.3.1. Data Plane Segmentation . . . . . . . . . . . . . . . 20 6.3.1. Data Plane Segmentation . . . . . . . . . . . . . . . 21
6.3.2. Controller Plane Segmentation . . . . . . . . . . . . 20 6.3.2. Controller Plane Segmentation . . . . . . . . . . . . 21
6.4. Replication and Elimination . . . . . . . . . . . . . . . 21 6.4. Replication and Elimination . . . . . . . . . . . . . . . 22
6.4.1. Increased Attack Surface . . . . . . . . . . . . . . 21 6.4.1. Increased Attack Surface . . . . . . . . . . . . . . 22
6.4.2. Header Manipulation at Elimination Routers . . . . . 21 6.4.2. Header Manipulation at Elimination Routers . . . . . 22
6.5. Control or Signaling Packet Modification . . . . . . . . 21 6.5. Control or Signaling Packet Modification . . . . . . . . 22
6.6. Control or Signaling Packet Injection . . . . . . . . . . 21 6.6. Control or Signaling Packet Injection . . . . . . . . . . 22
6.7. Reconnaissance . . . . . . . . . . . . . . . . . . . . . 21 6.7. Reconnaissance . . . . . . . . . . . . . . . . . . . . . 22
6.8. Attacks on Time Sync Mechanisms . . . . . . . . . . . . . 22 6.8. Attacks on Time Synchronization Mechanisms . . . . . . . 23
6.9. Attacks on Path Choice . . . . . . . . . . . . . . . . . 22 6.9. Attacks on Path Choice . . . . . . . . . . . . . . . . . 23
7. Security Threat Mitigation . . . . . . . . . . . . . . . . . 22 7. Security Threat Mitigation . . . . . . . . . . . . . . . . . 23
7.1. Path Redundancy . . . . . . . . . . . . . . . . . . . . . 22 7.1. Path Redundancy . . . . . . . . . . . . . . . . . . . . . 23
7.2. Integrity Protection . . . . . . . . . . . . . . . . . . 22 7.2. Integrity Protection . . . . . . . . . . . . . . . . . . 24
7.3. DetNet Node Authentication . . . . . . . . . . . . . . . 23 7.3. DetNet Node Authentication . . . . . . . . . . . . . . . 25
7.4. Dummy Traffic Insertion . . . . . . . . . . . . . . . . . 24 7.4. Dummy Traffic Insertion . . . . . . . . . . . . . . . . . 26
7.5. Encryption . . . . . . . . . . . . . . . . . . . . . . . 24 7.5. Encryption . . . . . . . . . . . . . . . . . . . . . . . 26
7.5.1. Encryption Considerations for DetNet . . . . . . . . 24 7.5.1. Encryption Considerations for DetNet . . . . . . . . 27
7.6. Control and Signaling Message Protection . . . . . . . . 25 7.6. Control and Signaling Message Protection . . . . . . . . 28
7.7. Dynamic Performance Analytics . . . . . . . . . . . . . . 26 7.7. Dynamic Performance Analytics . . . . . . . . . . . . . . 28
7.8. Mitigation Summary . . . . . . . . . . . . . . . . . . . 27 7.8. Mitigation Summary . . . . . . . . . . . . . . . . . . . 30
8. Association of Attacks to Use Cases . . . . . . . . . . . . . 28 8. Association of Attacks to Use Cases . . . . . . . . . . . . . 32
8.1. Association of Attacks to Use Case Common Themes . . . . 28 8.1. Association of Attacks to Use Case Common Themes . . . . 32
8.1.1. Sub-Network Layer . . . . . . . . . . . . . . . . . . 28 8.1.1. Sub-Network Layer . . . . . . . . . . . . . . . . . . 32
8.1.2. Central Administration . . . . . . . . . . . . . . . 29 8.1.2. Central Administration . . . . . . . . . . . . . . . 33
8.1.3. Hot Swap . . . . . . . . . . . . . . . . . . . . . . 29 8.1.3. Hot Swap . . . . . . . . . . . . . . . . . . . . . . 33
8.1.4. Data Flow Information Models . . . . . . . . . . . . 30 8.1.4. Data Flow Information Models . . . . . . . . . . . . 34
8.1.5. L2 and L3 Integration . . . . . . . . . . . . . . . . 30 8.1.5. L2 and L3 Integration . . . . . . . . . . . . . . . . 34
8.1.6. End-to-End Delivery . . . . . . . . . . . . . . . . . 30 8.1.6. End-to-End Delivery . . . . . . . . . . . . . . . . . 34
8.1.7. Replacement for Proprietary Fieldbuses and Ethernet- 8.1.7. Replacement for Proprietary Fieldbuses and Ethernet-
based Networks . . . . . . . . . . . . . . . . . . . 31 based Networks . . . . . . . . . . . . . . . . . . . 35
8.1.8. Deterministic vs Best-Effort Traffic . . . . . . . . 31 8.1.8. Deterministic vs Best-Effort Traffic . . . . . . . . 35
8.1.9. Deterministic Flows . . . . . . . . . . . . . . . . . 32 8.1.9. Deterministic Flows . . . . . . . . . . . . . . . . . 36
8.1.10. Unused Reserved Bandwidth . . . . . . . . . . . . . . 32 8.1.10. Unused Reserved Bandwidth . . . . . . . . . . . . . . 36
8.1.11. Interoperability . . . . . . . . . . . . . . . . . . 32 8.1.11. Interoperability . . . . . . . . . . . . . . . . . . 36
8.1.12. Cost Reductions . . . . . . . . . . . . . . . . . . . 32 8.1.12. Cost Reductions . . . . . . . . . . . . . . . . . . . 37
8.1.13. Insufficiently Secure Devices . . . . . . . . . . . . 33 8.1.13. Insufficiently Secure Components . . . . . . . . . . 37
8.1.14. DetNet Network Size . . . . . . . . . . . . . . . . . 33 8.1.14. DetNet Network Size . . . . . . . . . . . . . . . . . 37
8.1.15. Multiple Hops . . . . . . . . . . . . . . . . . . . . 34 8.1.15. Multiple Hops . . . . . . . . . . . . . . . . . . . . 38
8.1.16. Level of Service . . . . . . . . . . . . . . . . . . 34 8.1.16. Level of Service . . . . . . . . . . . . . . . . . . 38
8.1.17. Bounded Latency . . . . . . . . . . . . . . . . . . . 34 8.1.17. Bounded Latency . . . . . . . . . . . . . . . . . . . 39
8.1.18. Low Latency . . . . . . . . . . . . . . . . . . . . . 35 8.1.18. Low Latency . . . . . . . . . . . . . . . . . . . . . 39
8.1.19. Bounded Jitter (Latency Variation) . . . . . . . . . 35 8.1.19. Bounded Jitter (Latency Variation) . . . . . . . . . 39
8.1.20. Symmetrical Path Delays . . . . . . . . . . . . . . . 35 8.1.20. Symmetrical Path Delays . . . . . . . . . . . . . . . 39
8.1.21. Reliability and Availability . . . . . . . . . . . . 35 8.1.21. Reliability and Availability . . . . . . . . . . . . 40
8.1.22. Redundant Paths . . . . . . . . . . . . . . . . . . . 36 8.1.22. Redundant Paths . . . . . . . . . . . . . . . . . . . 40
8.1.23. Security Measures . . . . . . . . . . . . . . . . . . 36 8.1.23. Security Measures . . . . . . . . . . . . . . . . . . 40
8.2. Summary of Attack Types per Use Case Common Theme . . . . 36 8.2. Summary of Attack Types per Use Case Common Theme . . . . 41
8.3. Security Considerations for OAM Traffic . . . . . . . . . 39 8.3. Security Considerations for OAM Traffic . . . . . . . . . 43
9. DetNet Technology-Specific Threats . . . . . . . . . . . . . 39 9. DetNet Technology-Specific Threats . . . . . . . . . . . . . 43
9.1. IP . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 9.1. IP . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
9.2. MPLS . . . . . . . . . . . . . . . . . . . . . . . . . . 41 9.2. MPLS . . . . . . . . . . . . . . . . . . . . . . . . . . 45
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 42 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 46
11. Security Considerations . . . . . . . . . . . . . . . . . . . 42 11. Security Considerations . . . . . . . . . . . . . . . . . . . 46
12. Privacy Considerations . . . . . . . . . . . . . . . . . . . 42 12. Privacy Considerations . . . . . . . . . . . . . . . . . . . 46
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 42 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 46
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 43 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 47
14.1. Normative References . . . . . . . . . . . . . . . . . . 43 14.1. Normative References . . . . . . . . . . . . . . . . . . 47
14.2. Informative References . . . . . . . . . . . . . . . . . 44 14.2. Informative References . . . . . . . . . . . . . . . . . 48
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 47 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction 1. Introduction
A deterministic network is one that can carry data flows for real- A DetNet is one that can carry data flows for real-time applications
time applications with extremely low data loss rates and bounded with extremely low data loss rates and bounded latency. The bounds
latency. Deterministic networks have been successfully deployed in on latency defined by DetNet
real-time Operational Technology (OT) applications for some years. ([I-D.ietf-detnet-flow-information-model]) include both worst case
However, such networks are typically isolated from external access, latency (Maximum Latency, Section 5.9.2) and worst case jitter
and thus the security threat from external attackers is low. IETF (Maximum Latency Variation, Section 5.9.3). Deterministic networks
Deterministic Networking (DetNet, [RFC8655]) specifies a set of have been successfully deployed in real-time Operational Technology
technologies that enable creation of deterministic networks on IP- (OT) applications for some years, however such networks are typically
based networks of potentially wide area (on the scale of a corporate isolated from external access, and thus the security threat from
network) potentially bringing the OT network into contact with external attackers is low. IETF Deterministic Networking (DetNet,
Information Technology (IT) traffic and security threats that lie [RFC8655]) specifies a set of technologies that enable creation of
outside of a tightly controlled and bounded area (such as the deterministic flows on IP-based networks of potentially wide area (on
internals of an aircraft). the scale of a corporate network), potentially bringing the OT
network into contact with Information Technology (IT) traffic and
security threats that lie outside of a tightly controlled and bounded
area (such as the internals of an aircraft).
These DetNet technologies have not previously been deployed together These DetNet (OT-type) technologies may not have previously been
on a wide area IP-based network, and thus can present security deployed on a wide area IP-based network that also carries IT
considerations that may be new to IP-based wide area network traffic, and thus can present security considerations that may be new
designers; this document provides insight into such system-level to IP-based wide area network designers; this document provides
security considerations. In addition, designers of DetNet components insight into such system-level security considerations. In addition,
(such as routers) face new security-related challenges in providing designers of DetNet components (such as routers) face new security-
DetNet services, for example maintaining reliable isolation between related challenges in providing DetNet services, for example
traffic flows in an environment where IT traffic co-mingles with maintaining reliable isolation between traffic flows in an
critical reserved-bandwidth OT traffic; this document also examines environment where IT traffic co-mingles with critical reserved-
security implications internal to DetNet components. bandwidth OT traffic; this document also examines security
implications internal to DetNet components.
Security is of particularly high importance in DetNet networks Security is of particularly high importance in DetNet because many of
because many of the use cases which are enabled by DetNet [RFC8578] the use cases which are enabled by DetNet [RFC8578] include control
include control of physical devices (power grid components, of physical devices (power grid devices, industrial controls,
industrial controls, building controls) which can have high building controls) which can have high operational costs for failure,
operational costs for failure, and present potentially attractive and present potentially attractive targets for cyber-attackers.
targets for cyber-attackers.
This situation is even more acute given that one of the goals of This situation is even more acute given that one of the goals of
DetNet is to provide a "converged network", i.e. one that includes DetNet is to provide a "converged network", i.e. one that includes
both IT traffic and OT traffic, thus exposing potentially sensitive both IT traffic and OT traffic, thus exposing potentially sensitive
OT devices to attack in ways that were not previously common (usually OT devices to attack in ways that were not previously common (usually
because they were under a separate control system or otherwise because they were under a separate control system or otherwise
isolated from the IT network, for example [ARINC664P7]). Security isolated from the IT network, for example [ARINC664P7]). Security
considerations for OT networks are not a new area, and there are many considerations for OT networks are not a new area, and there are many
OT networks today that are connected to wide area networks or the OT networks today that are connected to wide area networks or the
Internet; this document focuses on the issues that are specific to Internet; this document focuses on the issues that are specific to
skipping to change at page 5, line 29 skipping to change at page 5, line 35
and controller plane; this is the assumed starting point for the and controller plane; this is the assumed starting point for the
considerations discussed herein. Such assumptions also depend on the considerations discussed herein. Such assumptions also depend on the
network components themselves upholding the security-related network components themselves upholding the security-related
properties that are to be assumed by DetNet system-level designers; properties that are to be assumed by DetNet system-level designers;
for example, the assumption that network traffic associated with a for example, the assumption that network traffic associated with a
given flow can never affect traffic associated with a different flow given flow can never affect traffic associated with a different flow
is only true if the underlying components make it so. Such is only true if the underlying components make it so. Such
properties, which may represent new challenges to component properties, which may represent new challenges to component
designers, are also considered herein. designers, are also considered herein.
In this context we view the network design and management aspects of In this context we view the "traditional" (i.e. non-time-sensitive)
network security as being primarily concerned with denial-of service network design and management aspects of network security as being
prevention by ensuring that DetNet traffic goes where it's supposed primarily concerned with denial-of service prevention, i.e. they must
to and that an external attacker can't inject traffic that disrupts ensure that DetNet traffic goes where it's supposed to and that an
the DetNet's delivery timing assurance. The time-specific aspects of external attacker can't inject traffic that disrupts the delivery
DetNet security presented here take up where the design and timing assurance of the DetNet. The time-specific aspects of DetNet
security presented here take up where those "traditional" design and
management aspects leave off. management aspects leave off.
The exact security requirements for any given DetNet network are However note that "traditional" methods for mitigating (among all the
necessarily specific to the use cases handled by that network. Thus others) denial-of service attack (such as throttling) can only be
the reader is assumed to be familiar with the specific security effectively used in a DetNet when their use does not compromise the
requirements of their use cases, for example those outlined in the required time-sensitive or behavioral properties required for the OT
DetNet Use Cases [RFC8578] and the Security Considerations sections flows on the network. For example, a "retry" protocol is typically
of the DetNet documents applicable to the network technologies in not going to be compatible with a low-latency (worst-case maximum
use, for example [I-D.ietf-detnet-ip]). A general introduction to latency) requirement, however if in a specific use case and
the DetNet architecture can be found in [RFC8655] and it is also implementation such a retry protocol is able to meet the timing
recommended to be familiar with the DetNet Data Plane constraints, then it may well be used in that context. Similarly if
[I-D.ietf-detnet-data-plane-framework] and Flow Information Model common security protocols such as TLS/DTLS or IPsec are to be used,
it must be verified that their implementations are able to meet the
timing and behavioral requirements of the time-sensitive network as
implemented for the given use case. An example of "behavioral
properties" might be that dropping of more than a specific number of
packets in a row is not acceptable according to the service level
agreement.
The exact security requirements for any given DetNet are necessarily
specific to the use cases handled by that network. Thus the reader
is assumed to be familiar with the specific security requirements of
their use cases, for example those outlined in the DetNet Use Cases
[RFC8578] and the Security Considerations sections of the DetNet
documents applicable to the network technologies in use, for example
[RFC8939]). Readers can find a general introduction to the DetNet
Architecture in [RFC8655], the DetNet Data Plane in [RFC8938], and
the Flow Information Model in
[I-D.ietf-detnet-flow-information-model]. [I-D.ietf-detnet-flow-information-model].
The DetNet technologies include ways to: The DetNet technologies include ways to:
o Assign data plane resources for DetNet flows in some or all of the o Assign data plane resources for DetNet flows in some or all of the
intermediate nodes (routers) along the path of the flow intermediate nodes (routers) along the path of the flow
o Provide explicit routes for DetNet flows that do not dynamically o Provide explicit routes for DetNet flows that do not dynamically
change with the network topology in ways that affect the quality change with the network topology in ways that affect the quality
of service received by the affected flow(s) of service received by the affected flow(s)
o Distribute data from DetNet flow packets over time and/or space to o Distribute data from DetNet flow packets over time and/or space to
ensure delivery of each packet's data' in spite of the loss of a ensure delivery of the data in each packet in spite of the loss of
path a path.
This document includes sections considering DetNet component design This document includes sections considering DetNet component design
as well as system design. The latter includes threat modeling and as well as system design. The latter includes threat modeling and
analysis, threat impact and mitigation, and the association of analysis, threat impact and mitigation, and the association of
attacks with use cases (based on the Use Case Common Themes section attacks with use cases (based on the Use Case Common Themes section
of the DetNet Use Cases [RFC8578]). of the DetNet Use Cases [RFC8578]).
The structure of the threat model and threat analysis sections were The structure of the threat model and threat analysis sections were
originally derived from [RFC7384], which also considers time-related originally derived from [RFC7384], which also considers time-related
security considerations in IP networks. security considerations in IP networks.
2. Abbreviations and Terminology 2. Abbreviations and Terminology
IT Information Technology (the application of computers to IT: Information Technology (the application of computers to store,
store, study, retrieve, transmit, and manipulate data or information, study, retrieve, transmit, and manipulate data or information, often
often in the context of a business or other enterprise - [IT_DEF]). in the context of a business or other enterprise - [IT_DEF]).
OT Operational Technology (the hardware and software OT: Operational Technology (the hardware and software dedicated to
dedicated to detecting or causing changes in physical processes detecting or causing changes in physical processes through direct
through direct monitoring and/or control of physical devices such as monitoring and/or control of physical devices such as valves, pumps,
valves, pumps, etc. - [OT_DEF]) etc. - [OT_DEF])
Component A component of a DetNet system - used here to refer Component: A component of a DetNet system - used here to refer to any
to any hardware or software element of a DetNet network which hardware or software element of a DetNet which implements DetNet-
implements DetNet-specific functionality, for example all or part of specific functionality, for example all or part of a router, switch,
a router, switch, or end system. or end system.
Resource Segmentation Used as a more general form for Network Device: Used here to refer to a physical entity controlled by the
DetNet, for example a motor.
Resource Segmentation Used as a more general form for Network
Segmentation (the act or practice of splitting a computer network Segmentation (the act or practice of splitting a computer network
into subnetworks, each being a network segment - [RS_DEF]) into subnetworks, each being a network segment - [RS_DEF])
3. Security Considerations for DetNet Component Design 3. Security Considerations for DetNet Component Design
As noted above, DetNet provides resource allocation, explicit routes As noted above, DetNet provides resource allocation, explicit routes
and redundant path support. Each of these has associated security and redundant path support. Each of these has associated security
implications, which are discussed in this section, in the context of implications, which are discussed in this section, in the context of
component design. Detection, reporting and appropriate action in the component design. Detection, reporting and appropriate action in the
case of packet arrival time violations are also discussed. case of packet arrival time violations are also discussed.
skipping to change at page 7, line 24 skipping to change at page 7, line 49
different manufacturer. From a security standpoint, this is a different manufacturer. From a security standpoint, this is a
critical assumption, for example when designing against DOS attacks. critical assumption, for example when designing against DOS attacks.
It is the responsibility of the component designer to ensure that It is the responsibility of the component designer to ensure that
this condition is met; this implies protection against excess traffic this condition is met; this implies protection against excess traffic
from adjacent flows, and against compromises to the resource from adjacent flows, and against compromises to the resource
allocation/deallocation process, for example through the use of allocation/deallocation process, for example through the use of
traffic shaping and policing. traffic shaping and policing.
As an example, consider the implementation of Flow Aggregation for As an example, consider the implementation of Flow Aggregation for
DetNet flows (as discussed in DetNet flows (as discussed in [RFC8938]). In this example say there
[I-D.ietf-detnet-data-plane-framework]). In this example say there
are N flows that are to be aggregated, thus the bandwidth resources are N flows that are to be aggregated, thus the bandwidth resources
of the aggregate flow must be sufficient to contain the sum of the of the aggregate flow must be sufficient to contain the sum of the
bandwidth reservation for the N flows. However if one of those flows bandwidth reservation for the N flows. However if one of those flows
were to consume more than its individually allocated BW, this could were to consume more than its individually allocated bandwidth, this
cause starvation of the other flows. Thus simply providing and could cause starvation of the other flows. Thus simply providing and
enforcing the calculated aggregate bandwidth may not be a complete enforcing the calculated aggregate bandwidth may not be a complete
solution - the bandwidth for each individual flow must still be solution - the bandwidth for each individual flow must still be
guaranteed, for example via ingress policing of each flow (i.e. guaranteed, for example via ingress policing of each flow (i.e.
before it is aggregated). Alternatively, if by some other means each before it is aggregated). Alternatively, if by some other means each
flow to be aggregated can be trusted not to exceed its allocated flow to be aggregated can be trusted not to exceed its allocated
bandwidth, the same goal can be achieved. bandwidth, the same goal can be achieved.
3.2. Explicit Routes 3.2. Explicit Routes
The DetNet-specific purpose for constraining the network's ability to The DetNet-specific purpose for constraining the ability of the
re-route OT traffic is to maintain the specified service parameters DetNet to re-route OT traffic is to maintain the specified service
(such as upper and lower latency boundaries) for a given flow. For parameters (such as upper and lower latency boundaries) for a given
example if the network were to re-route a flow (or some part of a flow. For example if the network were to re-route a flow (or some
flow) based exclusively on statistical path usage metrics, or due to part of a flow) based exclusively on statistical path usage metrics,
malicious activity, it is possible that the new path would have a or due to malicious activity, it is possible that the new path would
latency that is outside the required latency bounds which were have a latency that is outside the required latency bounds which were
designed into the original TE-designed path, thereby violating the designed into the original TE-designed path, thereby violating the
quality of service for the affected flow (or part of that flow). quality of service for the affected flow (or part of that flow).
However, it is acceptable for the network to re-route OT traffic in However, it is acceptable for the network to re-route OT traffic in
such a way as to maintain the specified latency bounds (and any other such a way as to maintain the specified latency bounds (and any other
specified service properties) for any reason, for example in response specified service properties) for any reason, for example in response
to a runtime component or path failure. From a security standpoint, to a runtime component or path failure. From a security standpoint,
the system designer relies on the premise that the packets will be the system designer relies on the premise that the packets will be
delivered with the specified latency boundaries; thus any component delivered with the specified latency boundaries; thus any component
that is involved in controlling or implementing any change of the that is involved in controlling or implementing any change of the
skipping to change at page 8, line 36 skipping to change at page 9, line 13
component designer to ensure that the relevant PREOF operations are component designer to ensure that the relevant PREOF operations are
executed reliably and securely, to avoid potentially catastrophic executed reliably and securely, to avoid potentially catastrophic
situations for the operational technology relying on them. situations for the operational technology relying on them.
However, note that not all PREOF operations are necessarily However, note that not all PREOF operations are necessarily
implemented in every network; for example a packet re-ordering implemented in every network; for example a packet re-ordering
function may not be necessary if the packets are either not required function may not be necessary if the packets are either not required
to be in order, or if the ordering is performed in some other part of to be in order, or if the ordering is performed in some other part of
the network. the network.
Ideally a redundant path could be specified from end to end of the Ideally a redundant path for a flow could be specified from end to
flow's path, however given that this is not always possible (as end, however given that this is not always possible (as described in
described in [RFC8655]) the system designer will need to consider the [RFC8655]) the system designer will need to consider the resulting
resulting end-to-end reliability and security resulting from any end-to-end reliability and security resulting from any given
given arrangment of network segments along the path, each of which arrangment of network segments along the path, each of which provides
provides its individual PREOF implementation and thus its individual its individual PREOF implementation and thus its individual level of
level of reliabiilty and security. reliabiilty and security.
At the data plane the implementation of PREOF depends on the correct At the data plane the implementation of PREOF depends on the correct
assignment and interpretation of packet sequence numbers, as well as assignment and interpretation of packet sequence numbers, as well as
the actions taken based on them, such as elimination (including the actions taken based on them, such as elimination (including
elimination of packets with spurious sequence numbers). Thus the elimination of packets with spurious sequence numbers). Thus the
integrity of these values must be maintained by the component as they integrity of these values must be maintained by the component as they
are assigned by the DetNet Data Plane's Service sub-layer, and are assigned by the DetNet Data Plane Service sub-layer, and
transported by the Forwarding sub-layer. This is no different than transported by the Forwarding sub-layer. This is no different than
the integrity of the values in any header used by the DetNet (or any the integrity of the values in any header used by the DetNet (or any
other) data plane, and is not unique to redundant paths. From the other) data plane, and is not unique to redundant paths. The
integrity protection of header values is technology-dependent; for
example, in Layer 2 networks the integrity of the header fields can
be protected by using MACsec [IEEE802.1AE-2018]. Similary, from the
sequence number injection perspective, it is no different from any sequence number injection perspective, it is no different from any
other protocols that use sequence numbers. other protocols that use sequence numbers.
3.4. Timing (or other) Violation Reporting 3.4. Timing (or other) Violation Reporting
Another fundamental assumption of a secure DetNet is that in any case Another fundamental assumption of a secure DetNet is that in any case
in which an incoming packet arrives with any timing or bandwidth in which an incoming packet arrives with any timing or bandwidth
violation, something can be done about it which doesn't cause damage violation, something can be done about it which doesn't cause damage
to the system. For example having the network shut down a link if a to the system. For example having the network shut down a link if a
packet arrives outside of its prescribed time window may serve the packet arrives outside of its prescribed time window may serve the
attacker better than it serves the network. That means that the attacker better than it serves the network. That means that the data
component's data plane must be able to detect and act on a variety of plane of the component must be able to detect and act on a variety of
such violations, at least alerting the controller plane. Any action such violations, at least alerting the controller plane. Any action
apart from that needs to be carefully considered in the context of apart from that needs to be carefully considered in the context of
the specific system. Some possible violations that warrant detection the specific system. Some possible violations that warrant detection
include cases where a packet arrives: include cases where a packet arrives:
o Outside of its prescribed time window o Outside of its prescribed time window
o Within its time window but with a compromised time stamp that o Within its time window but with a compromised time stamp that
makes it appear that it is not within its window makes it appear that it is not within its window
o Exceeding the reserved flow bandwidth o Exceeding the reserved flow bandwidth
Logging of such issues is unlikely to be adequate, since a delay in Logging of such issues is unlikely to be adequate, since a delay in
response to the situation could result in material damage, for response to the situation could result in material damage, for
example to mechanical devices controlled by the network. Given that example to mechanical devices controlled by the network. Given that
the data plane component probably has no knowledge of the use case of the data plane component probably has no knowledge of the use case of
the network, or its applications and end systems, it would seem the network, or its applications and end systems, it would seem
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o Exceeding the reserved flow bandwidth o Exceeding the reserved flow bandwidth
Logging of such issues is unlikely to be adequate, since a delay in Logging of such issues is unlikely to be adequate, since a delay in
response to the situation could result in material damage, for response to the situation could result in material damage, for
example to mechanical devices controlled by the network. Given that example to mechanical devices controlled by the network. Given that
the data plane component probably has no knowledge of the use case of the data plane component probably has no knowledge of the use case of
the network, or its applications and end systems, it would seem the network, or its applications and end systems, it would seem
useful for a data plane component to allow the system designer to useful for a data plane component to allow the system designer to
configure its actions in the face of such violations. configure its actions in the face of such violations.
Possible direct actions that may be taken at the data plane include Some possible direct actions that may be taken at the data plane
dropping the packet and/or shutting down the link; however if any include traffic policing and shaping functions (e.g., those described
such actions are configured to be taken, the system designer must in [RFC2475]), separating flows into per-flow rate-limited queues,
ensure that such actions do not compromise the continued safe and potentially applying active queue management [RFC7567]. However
operation of the system. For example, the controller plane should if those (or any other) actions are to be taken, the system designer
must ensure that the results of such actions do not compromise the
continued safe operation of the system. For example, the network
(i.e. the controller plane and data plane working together) must
mitigate in a timely fashion any potential adverse effect on mitigate in a timely fashion any potential adverse effect on
mechanical devices controlled by the network. mechanical devices controlled by the network.
4. DetNet Security Considerations Compared With DiffServ Security 4. DetNet Security Considerations Compared With DiffServ Security
Considerations Considerations
DetNet is designed to be compatible with DiffServ [RFC2474] as DetNet is designed to be compatible with DiffServ [RFC2474] as
applied to IT traffic in the DetNet. DetNet also incorporates the applied to IT traffic in the DetNet. DetNet also incorporates the
use of the 6-bit value of the DSCP field of the TOS field of the IP use of the 6-bit value of the DSCP field of the TOS field of the IP
header for flow identification for OT traffic, however the DetNet header for flow identification for OT traffic, however the DetNet
interpretation of the DSCP value for OT traffic is not equivalent to interpretation of the DSCP value for OT traffic is not equivalent to
the PHB selection behavior as defined by DiffServ. the PHB selection behavior as defined by DiffServ.
Thus security consideration for DetNet have some aspects in common Thus security consideration for DetNet have some aspects in common
with DiffServ, in fact overlapping 100% with respect to IP IT with DiffServ, in fact overlapping 100% with respect to IP IT
traffic. Security considerations for these aspects are part of the traffic. Security considerations for these aspects are part of the
existing literature on IP network security, specifically the Security existing literature on IP network security, specifically the Security
sections of [RFC2474] and [RFC2475]. However DetNet also introduces Considerations sections of [RFC2474] and [RFC2475]. However DetNet
timing and other considerations which are not present in DiffServ, so also introduces timing and other considerations which are not present
the DiffServ security considerations are necessary but not sufficient in DiffServ, so the DiffServ security considerations are necessary
for DetNet. but not sufficient for DetNet.
In the case of DetNet OT traffic, the DSCP value, although In the case of DetNet OT traffic, the DSCP value is interpreted
interpreted differently than in DiffServ, does contribute to differently than in DiffServ and contribute to determination of the
determination of the service provided to the packet. Thus in DetNet service provided to the packet. In DetNet, there are similar
there are similar consequences to DiffServ for lack of detection of, consequences to DiffServ for lack of detection of, or incorrect
or incorrect handling of, packets with mismarked DSCP values, and handling of, packets with mismarked DSCP values, and many of the
thus many of the points made in the DiffServ draft Security points made in the DiffServ Security discussions ([RFC2475] Sec. 6.1
discussions are also relevant to DetNet OT traffic, though perhaps in , [RFC2474] Sec. 7 and [RFC6274] Sec 3.3.2.1) are also relevant to
modified form. For example, in DetNet the effect of an undetected or DetNet OT traffic, though perhaps in modified form. For example, in
incorrectly handled maliciously mismarked DSCP field in an OT packet DetNet the effect of an undetected or incorrectly handled maliciously
is not identical to affecting that packet's PHB, since DetNet does mismarked DSCP field in an OT packet is not identical to affecting
not use the PHB concept for OT traffic, but nonetheless the service the PHB of that packet, since DetNet does not use the PHB concept for
provided to the packet could be affected, so mitigation measures OT traffic; but nonetheless the service provided to the packet could
analogous to those prescribed by DiffServ would be appropriate for be affected, so mitigation measures analogous to those prescribed by
DetNet. For example, mismarked DSCP values should not cause failure DiffServ would be appropriate for DetNet. For example, mismarked
of network nodes, and any internal link that cannot be adequately DSCP values should not cause failure of network nodes. The remarks
secured against modification of DSCP values should be treated as a
boundary link (and hence any arriving traffic on that link is treated
as if it were entering the domain at an ingress node). The remarks
in [RFC2474] regarding IPsec and Tunnelling Interactions are also in [RFC2474] regarding IPsec and Tunnelling Interactions are also
relevant (though this is not to say that other sections are less relevant (though this is not to say that other sections are less
relevant). relevant).
5. Security Threats 5. Security Threats
This section presents a threat model, and analyzes the possible This section presents a threat model, and analyzes the possible
threats in a DetNet-enabled network. The threats considered in this threats in a DetNet-enabled network. The threats considered in this
section are independent of any specific technologies used to section are independent of any specific technologies used to
implement the DetNet; Section 9 considers attacks that are associated implement the DetNet; Section 9 considers attacks that are associated
with the DetNet technologies encompassed by with the DetNet technologies encompassed by [RFC8938].
[I-D.ietf-detnet-data-plane-framework].
We distinguish controller plane threats from data plane threats. The We distinguish controller plane threats from data plane threats. The
attack surface may be the same, but the types of attacks as well as attack surface may be the same, but the types of attacks as well as
the motivation behind them, are different. For example, a delay the motivation behind them, are different. For example, a delay
attack is more relevant to data plane than to controller plane. attack is more relevant to data plane than to controller plane.
There is also a difference in terms of security solutions: the way There is also a difference in terms of security solutions: the way
you secure the data plane is often different than the way you secure you secure the data plane is often different than the way you secure
the controller plane. the controller plane.
5.1. Threat Model 5.1. Threat Model
The threat model used in this memo employs organizational elements of The threat model used in this document employs organizational
the threat models of [RFC7384] and [RFC7835] . This model classifies elements of the threat models of [RFC7384] and [RFC7835]. This model
attackers based on two criteria: classifies attackers based on two criteria:
o Internal vs. external: internal attackers either have access to a o Internal vs. external: internal attackers either have access to a
trusted segment of the network or possess the encryption or trusted segment of the network or possess the encryption or
authentication keys. External attackers, on the other hand, do authentication keys. External attackers, on the other hand, do
not have the keys and have access only to the encrypted or not have the keys and have access only to the encrypted or
authenticated traffic. authenticated traffic.
o On-path vs. off-path: on-path attackers are located in a position o On-path vs. off-path: on-path attackers are located in a position
that allows interception and modification of in-flight protocol that allows interception and modification of in-flight protocol
packets, whereas off-path attackers can only attack by generating packets, whereas off-path attackers can only attack by generating
skipping to change at page 11, line 37 skipping to change at page 12, line 18
(explored further in Section 5.2, Threat Analysis). Most of the (explored further in Section 5.2, Threat Analysis). Most of the
direct threats to DetNet are active attacks (i.e. attacks that modify direct threats to DetNet are active attacks (i.e. attacks that modify
DetNet traffic), but it is highly suggested that DetNet application DetNet traffic), but it is highly suggested that DetNet application
developers take appropriate measures to protect the content of the developers take appropriate measures to protect the content of the
DetNet flows from passive attacks (i.e. attacks that observe but do DetNet flows from passive attacks (i.e. attacks that observe but do
not modify DetNet traffic) for example through the use of TLS or not modify DetNet traffic) for example through the use of TLS or
DTLS. DTLS.
DetNet-Service, one of the service scenarios described in DetNet-Service, one of the service scenarios described in
[I-D.varga-detnet-service-model], is the case where a service [I-D.varga-detnet-service-model], is the case where a service
connects DetNet networking islands, i.e. two or more otherwise connects DetNet islands, i.e. two or more otherwise independent
independent DetNet network domains are connected via a link that is DetNets are connected via a link that is not intrinsically part of
not intrinsically part of either network. This implies that there either network. This implies that there could be DetNet traffic
could be DetNet traffic flowing over a non-DetNet link, which may flowing over a non-DetNet link, which may provide an attacker with an
provide an attacker with an advantageous opportunity to tamper with advantageous opportunity to tamper with DetNet traffic. The security
DetNet traffic. The security properties of non-DetNet links are properties of non-DetNet links are outside of the scope of DetNet
outside of the scope of DetNet Security, but it should be noted that Security, but it should be noted that use of non-DetNet services to
use of non-DetNet services to interconnect DetNet networks merits interconnect DetNets merits security analysis to ensure the integrity
security analysis to ensure the integrity of the DetNet networks of the networks involved.
involved.
5.2. Threat Analysis 5.2. Threat Analysis
5.2.1. Delay 5.2.1. Delay
An attacker can maliciously delay DetNet data flow traffic. By An attacker can maliciously delay DetNet data flow traffic. By
delaying the traffic, the attacker can compromise the service of delaying the traffic, the attacker can compromise the service of
applications that are sensitive to high delays or to high delay applications that are sensitive to high delays or to high delay
variation. The delay may be constant or modulated. variation. The delay may be constant or modulated.
skipping to change at page 14, line 11 skipping to change at page 14, line 32
increased attack surface. Thus, when the attack described in the increased attack surface. Thus, when the attack described in the
previous subsection is implemented, it may increase the potential of previous subsection is implemented, it may increase the potential of
other attacks to be performed. other attacks to be performed.
5.2.5.2. Compromised Controller 5.2.5.2. Compromised Controller
An attacker can subvert a controller, or enable a compromised An attacker can subvert a controller, or enable a compromised
controller to falsely represent itself as a controller so that the controller to falsely represent itself as a controller so that the
network nodes believe it to be authorized to instruct them. network nodes believe it to be authorized to instruct them.
Presence of compromised nodes in a DetNet is not a "new" threat that Presence of compromised nodes in a DetNet is not a new threat that
arises as a result of determinism or time sensitivity; the same arises as a result of determinism or time sensitivity; the same
techniques used to prevent or mitigate against compromised nodes in techniques used to prevent or mitigate against compromised nodes in
any network are equally applicable in the DetNet case. However this any network are equally applicable in the DetNet case. However this
underscores the requirement for careful system security design in a underscores the requirement for careful system security design in a
DetNet, given that the effects of even one bad actor on the network DetNet, given that the effects of even one bad actor on the network
can be potentially catastrophic. can be potentially catastrophic.
Security concerns specific to any given controller plane technology Security concerns specific to any given controller plane technology
used in DetNet will be addressed by the DetNet documents associated used in DetNet will be addressed by the DetNet documents associated
with that technology. with that technology.
5.2.6. Reconnaissance 5.2.6. Reconnaissance
A passive eavesdropper can identify DetNet flows and then gather A passive eavesdropper can identify DetNet flows and then gather
information about en route DetNet flows, e.g., the number of DetNet information about en route DetNet flows, e.g., the number of DetNet
flows, their bandwidths, their schedules, or other temporal flows, their bandwidths, their schedules, or other temporal
properties. The gathered information can later be used to invoke properties. The gathered information can later be used to invoke
other attacks on some or all of the flows. other attacks on some or all of the flows.
Note that in some cases DetNet flows may be identified based on an DetNet flows are typically uniquely identified by their 6-tuple, i.e.
explicit DetNet header, but in some cases the flow identification may fields within the IP header, however in some implementations the flow
be based on fields from the L3/L4 headers. If L3/L4 headers are ID may also be augmented by additional per-flow attributes known to
involved, for the purposes of this document we assume they are the system, e.g. above the IP-layer. For the purpose of this
document we assume any such additional fields used for flow ID are
encrypted and/or integrity-protected from external attackers. encrypted and/or integrity-protected from external attackers.
5.2.7. Time Synchronization Mechanisms 5.2.7. Time Synchronization Mechanisms
An attacker can use any of the attacks described in [RFC7384] to An attacker can use any of the attacks described in [RFC7384] to
attack the synchronization protocol, thus affecting the DetNet attack the synchronization protocol, thus affecting the DetNet
service. service.
5.3. Threat Summary 5.3. Threat Summary
A summary of the attacks that were discussed in this section is A summary of the attacks that were discussed in this section is
presented in Figure 1. For each attack, the table specifies the type presented in Figure 1. For each attack, the table specifies the type
of attackers that may invoke the attack. In the context of this of attackers that may invoke the attack. In the context of this
summary, the distinction between internal and external attacks is summary, the distinction between internal and external attacks is
under the assumption that a corresponding security mechanism is being under the assumption that a corresponding security mechanism is being
used, and that the corresponding network equipment takes part in this used, and that the corresponding network equipment takes part in this
mechanism. mechanism.
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
| Attack | Attacker Type | | Attack | Attacker Type |
| +---------+---------+ | +----------+----------+
| |Internal |External | | | Internal | External |
| |On-P|Off-P|On-P|Off-P| | |On-P|Off-P|On-P|Off-P|
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Delay attack | + | + | + | + | |Delay attack | + | + | + | + |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|DetNet Flow Modification or Spoofing | + | + | | | |DetNet Flow Modification or Spoofing | + | + | | |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Inter-segment Attack | + | + | | | |Inter-segment Attack | + | + | + | + |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Replication: Increased Attack Surface | + | + | + | + | |Replication: Increased Attack Surface | + | + | + | + |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Replication-related Header Manipulation | + | | | | |Replication-related Header Manipulation | + | | | |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Path Manipulation | + | + | | | |Path Manipulation | + | + | | |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Path Choice: Increased Attack Surface | + | + | + | + | |Path Choice: Increased Attack Surface | + | + | + | + |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Control or Signaling Packet Modification | + | | | | |Control or Signaling Packet Modification | + | | | |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Control or Signaling Packet Injection | | + | | | |Control or Signaling Packet Injection | + | + | | |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Reconnaissance | + | | + | | |Reconnaissance | + | | + | |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
|Attacks on Time Sync Mechanisms | + | + | + | + | |Attacks on Time Synchronization Mechanisms | + | + | + | + |
+-----------------------------------------+----+----+----+----+ +-------------------------------------------+----+-----+----+-----+
Figure 1: Threat Analysis Summary Figure 1: Threat Analysis Summary
6. Security Threat Impacts 6. Security Threat Impacts
This section describes and rates the impact of the attacks described This section describes and rates the impact of the attacks described
in Section 5, Security Threats. In this section, the impacts as in Section 5, Security Threats. In this section, the impacts as
described assume that the associated mitigation is not present or has described assume that the associated mitigation is not present or has
failed. Mitigations are discussed in Section 7, Security Threat failed. Mitigations are discussed in Section 7, Security Threat
Mitigation. Mitigation.
In computer security, the impact (or consequence) of an incident can In computer security, the impact (or consequence) of an incident can
be measured in loss of confidentiality, integrity or availability of be measured in loss of confidentiality, integrity or availability of
information. In the case of time sensitive networks, the impact of a information. In the case of time sensitive networks, the impact of a
network exploit can also include failure or malfunction of mechanical network exploit can also include failure or malfunction of mechanical
and/or other OT systems. and/or other OT systems.
DetNet raises these stakes significantly for OT applications, DetNet raises these stakes significantly for OT applications,
particularly those which may have been designed to run in an OT-only particularly those which may have been designed to run in an OT-only
environment and thus may not have been designed for security in an IT environment and thus may not have been designed for security in an IT
environment with its associated devices, services and protocols. environment with its associated components, services and protocols.
The severity of various components of the impact of a successful The extent of impact of a successful vulnerability exploit varies
vulnerability exploit to use cases by industry is available in more considerably by use case and by industry; additional insights
detail in the DetNet Use Cases [RFC8578]. Each of these use cases is regarding the individual use cases is available from [RFC8578],
represented in the table below, including Pro Audio, Electrical DetNet Use Cases. Each of those use cases is represented in
Utilities, Industrial M2M (split into two areas, M2M Data Gathering Figure 2, including Pro Audio, Electrical Utilities, Industrial M2M
and M2M Control Loop), and others. (split into two areas, M2M Data Gathering and M2M Control Loop), and
others.
Components of Impact (left column) include Criticality of Failure, Aspects of Impact (left column) include Criticality of Failure,
Effects of Failure, Recovery, and DetNet Functional Dependence. Effects of Failure, Recovery, and DetNet Functional Dependence.
Criticality of failure summarizes the seriousness of the impact. The Criticality of failure summarizes the seriousness of the impact. The
impact of a resulting failure can affect many different metrics that impact of a resulting failure can affect many different metrics that
vary greatly in scope and severity. In order to reduce the number of vary greatly in scope and severity. In order to reduce the number of
variables, only the following were included: Financial, Health and variables, only the following were included: Financial, Health and
Safety, People well being (People WB), Affect on a single Safety, People well being (People WB), Affect on a single
organization, and affect on multiple organizations. Recovery organization, and affect on multiple organizations. Recovery
outlines how long it would take for an affected use case to get back outlines how long it would take for an affected use case to get back
to its pre-failure state (Recovery time objective, RTO), and how much to its pre-failure state (Recovery time objective, RTO), and how much
of the original service would be lost in between the time of service of the original service would be lost in between the time of service
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DetNet flow have strict deterministic requirements. DetNet flow have strict deterministic requirements.
For a single path scenario, disruption is a real possibility, whereas For a single path scenario, disruption is a real possibility, whereas
in a multipath scenario, large delays or instabilities in one DetNet in a multipath scenario, large delays or instabilities in one DetNet
flow can lead to increased buffer and processor resources at the flow can lead to increased buffer and processor resources at the
eliminating router. eliminating router.
A data-plane delay attack on a system controlling substantial moving A data-plane delay attack on a system controlling substantial moving
devices, for example in industrial automation, can cause physical devices, for example in industrial automation, can cause physical
damage. For example, if the network promises a bounded latency of damage. For example, if the network promises a bounded latency of
2ms for a flow, yet the machine receives it with 5ms latency, the 2ms for a flow, yet the machine receives it with 5ms latency, control
machine's control loop can become unstable. loop of the machine can become unstable.
6.1.2. Controller Plane Delay Attacks 6.1.2. Controller Plane Delay Attacks
In and of itself, this is not directly a threat to the DetNet In and of itself, this is not directly a threat to the DetNet
service, but the effects of delaying control messages can have quite service, but the effects of delaying control messages can have quite
adverse effects later. adverse effects later.
o Delayed tear-down can lead to resource leakage, which in turn can o Delayed tear-down can lead to resource leakage, which in turn can
result in failure to allocate new DetNet flows, finally giving result in failure to allocate new DetNet flows, finally giving
rise to a denial of service attack. rise to a denial of service attack.
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adverse effects. It can do virtually anything from: adverse effects. It can do virtually anything from:
o modifying existing DetNet flows by changing the available o modifying existing DetNet flows by changing the available
bandwidth bandwidth
o add or remove endpoints from a DetNet flow o add or remove endpoints from a DetNet flow
o drop DetNet flows completely o drop DetNet flows completely
o falsely create new DetNet flows (exhaust the systems resources, or o falsely create new DetNet flows (exhaust the systems resources, or
to enable DetNet flows that are outside the Network Engineer's to enable DetNet flows that are outside the control of the Network
control) Engineer)
6.3. Segmentation Attacks (injection) 6.3. Segmentation Attacks (injection)
6.3.1. Data Plane Segmentation 6.3.1. Data Plane Segmentation
Injection of false messages in a DetNet flow could lead to exhaustion Injection of false messages in a DetNet flow could lead to exhaustion
of the available bandwidth for that flow if the routers attribute of the available bandwidth for that flow if the routers attribute
these false messages to that flow's budget. these false messages to the resource budget of that flow.
In a multipath scenario, injected messages will cause increased In a multipath scenario, injected messages will cause increased
processor utilization in elimination routers. If enough paths are processor utilization in elimination routers. If enough paths are
subject to malicious injection, the legitimate messages can be subject to malicious injection, the legitimate messages can be
dropped. Likewise it can cause an increase in buffer usage. In dropped. Likewise it can cause an increase in buffer usage. In
total, it will consume more resources in the routers than normal, total, it will consume more resources in the routers than normal,
giving rise to a resource exhaustion attack on the routers. giving rise to a resource exhaustion attack on the routers.
If a DetNet flow is interrupted, the end application will be affected If a DetNet flow is interrupted, the end application will be affected
by what is now a non-deterministic flow. by what is now a non-deterministic flow.
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The flow-id in the header of the data plane messages gives an The flow-id in the header of the data plane messages gives an
attacker a very reliable identifier for DetNet traffic, and this attacker a very reliable identifier for DetNet traffic, and this
traffic has a high probability of going to lucrative targets. traffic has a high probability of going to lucrative targets.
Applications which are ported from a private OT network to the higher Applications which are ported from a private OT network to the higher
visibility DetNet environment may need to be adapted to limit visibility DetNet environment may need to be adapted to limit
distinctive flow properties that could make them susceptible to distinctive flow properties that could make them susceptible to
reconnaissance. reconnaissance.
6.8. Attacks on Time Sync Mechanisms 6.8. Attacks on Time Synchronization Mechanisms
Attacks on time sync mechanisms are addressed in [RFC7384]. Attacks on time synchronization mechanisms are addressed in
[RFC7384].
6.9. Attacks on Path Choice 6.9. Attacks on Path Choice
This is covered in part in Section 6.3, Segmentation Attacks, and as This is covered in part in Section 6.3, Segmentation Attacks, and as
with Replication and Elimination (Section 6.4), this is relevant for with Replication and Elimination ( Section 6.4), this is relevant for
DataPlane messages. DataPlane messages.
7. Security Threat Mitigation 7. Security Threat Mitigation
This section describes a set of measures that can be taken to This section describes a set of measures that can be taken to
mitigate the attacks described in Section 5, Security Threats. These mitigate the attacks described in Section 5, Security Threats. These
mitigations should be viewed as a toolset that includes several mitigations should be viewed as a toolset that includes several
different and diverse tools. Each application or system will different and diverse tools. Each application or system will
typically use a subset of these tools, based on a system-specific typically use a subset of these tools, based on a system-specific
threat analysis. threat analysis.
Some of the technology-specific security considerations and
mitigation approaches are further discussed in the DETNET data plane
solution documents, such as [RFC8939], [RFC8938],
[I-D.ietf-detnet-mpls-over-udp-ip], and
[I-D.ietf-detnet-ip-over-mpls].
7.1. Path Redundancy 7.1. Path Redundancy
Description Description
A DetNet flow that can be forwarded simultaneously over multiple A DetNet flow that can be forwarded simultaneously over multiple
paths. Path replication and elimination [RFC8655] provides paths. Path replication and elimination [RFC8655] provides
resiliency to dropped or delayed packets. This redundancy resiliency to dropped or delayed packets. This redundancy
improves the robustness to failures and to on-path attacks. Note: improves the robustness to failures and to on-path attacks. Note:
At the time of this writing, PREOF is not defined for the IP data At the time of this writing, PREOF is not defined for the IP data
plane. plane.
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source of an on-path attacker. source of an on-path attacker.
A delay modulation attack could result in extensively exercising A delay modulation attack could result in extensively exercising
parts of the code that wouldn't normally be extensively exercised parts of the code that wouldn't normally be extensively exercised
and thus might expose flaws in the system that might otherwise not and thus might expose flaws in the system that might otherwise not
be exposed. be exposed.
7.2. Integrity Protection 7.2. Integrity Protection
Description Description
An integrity protection mechanism, such as a hash-based Message
Authentication Code (MAC) can be used to mitigate modification
attacks on IP packets. Such MAC usage needs to be part of a
security association that is established and managed by a security
association protocol (such as IKEv2 for IPsec security
associations). Integrity protection in the controller plane is
discussed in Section 7.6.
Packet Sequence Number Integrity Considerations Integrity Protection in the scope of DetNet is the ability to
detect if a header has been modified (either maliciously or by
chance) and propagate a warning to a responsible monitoring agent.
An integrity protection mechanism is designed to counteract header
modification attacks where a Message Authentication Code (MAC) is
the most common. The MAC can be distributed either in-line
(included in the same packet) or via a side channel. Due to the
nature of DetNet traffic. Note: a sideband approach may yield too
high overhead and complexity and should only be used as a very
last resort if in-line approaches are not viable.
There are different levels of security available for integrity
protection, ranging from the basic ability to detect if a header
has been corrupted in transit (no malicious attack) to stopping a
skilled and determined attacker capable of both subtly modifying
fields in the headers as well as updating an unsigned MAC. Common
for all are the 2 steps that need to be performed in both ends.
The first is computing the checksum or MAC. The corresponding
verification step must perform the same steps before comparing the
provided with the computed value. Only then can the receiver be
reasonably sure that the header is authentic.
The most basic protection mechanism consists of computing a simple
checksum of the header fields and provide it to the next entity in
the packets path for verification. Using a MAC combined with a
secret key provides the best protection against modification and
replication attacks (see Section 5.2.2 and Section 5.2.4). This
MAC usage needs to be part of a security association that is
established and managed by a security association protocol (such
as IKEv2 for IPsec security associations). Integrity protection
in the controller plane is discussed in Section 7.6. The secret
key, regardless of MAC used, must be protected from falling into
the hands of unauthorized users.
DetNet system- and/or component- level designers need to be aware
of these distinctions and enforce appropriate integrity protection
mechanisms as needed based on a threat analysis. Note that adding
integrity protection mechanisms may introduce latency, thus many
of the same considerations in Section 7.5.1 also apply here.
Packet Sequence Number Integrity Considerations
The use of PREOF in a DetNet implementation implies the use of a The use of PREOF in a DetNet implementation implies the use of a
sequence number for each packet. There is a trust relationship sequence number for each packet. There is a trust relationship
between the device that adds the sequence number and the device between the component that adds the sequence number and the
that removes the sequence number. The sequence number may be end- component that removes the sequence number. The sequence number
to-end source to destination, or may be added/deleted by network may be end-to-end source to destination, or may be added/deleted
edge devices. The adder and remover(s) have the trust by network edge components. The adder and remover(s) have the
relationship because they are the ones that ensure that the trust relationship because they are the ones that ensure that the
sequence numbers are not modifiable. Between those two points, sequence numbers are not modifiable. Thus, sequence numbers can
there may or may not be replication and elimination functions. be protected by using encryption, or by a MAC without using
The elimination functions must be able to see the sequence encryption. Between the adder and remover there may or may not be
numbers. Therefore any encryption that is done between adders and replication and elimination functions. The elimination functions
removers must not obscure the sequence number. If the sequence must be able to see the sequence numbers. Therefore, if
removers and the eliminators are in the same physical device, it encryption is done between adders and removers it must not obscure
may be possible to obscure the sequence number, however that is a the sequence number. If the sequence removers and the eliminators
layer violation, and is not recommended practice. Note: At the are in the same physical component, it may be possible to obscure
time of this writing, PREOF is not defined for the IP data plane. the sequence number, however that is a layer violation, and is not
recommended practice. Note: At the time of this writing, PREOF is
not defined for the IP data plane.
Related attacks Related attacks
Integrity protection mitigates attacks related to modification and Integrity protection mitigates attacks related to modification and
tampering, including the attacks described in Section 5.2.2 and tampering, including the attacks described in Section 5.2.2 and
Section 5.2.4. Section 5.2.4.
7.3. DetNet Node Authentication 7.3. DetNet Node Authentication
Description Description
Authentication verifies the identity of DetNet nodes (including Authentication verifies the identity of DetNet nodes (including
DetNet Controller Plane nodes), enabling mitigation of spoofing DetNet Controller Plane nodes), and this enables mitigation of
attacks. Note that while integrity protection (Section 7.2) spoofing attacks. While integrity protection ( Section 7.2)
prevents intermediate nodes from modifying information, prevents intermediate nodes from modifying information,
authentication (such as provided by IPsec or MACsec) can provide authentication (such as IPsec [RFC4301] or MACsec
traffic origin verification, i.e. to verify that each packet in a [IEEE802.1AE-2018]) can provide traffic origin verification, i.e.
DetNet flow is from a trusted source. to verify that each packet in a DetNet flow is from a known
source.
Related attacks Related attacks
DetNet node authentication is used to mitigate attacks related to DetNet node authentication is used to mitigate attacks related to
spoofing, including the attacks of Section 5.2.2, and spoofing, including the attacks of Section 5.2.2, and
Section 5.2.4. Section 5.2.4.
7.4. Dummy Traffic Insertion 7.4. Dummy Traffic Insertion
Description Description
With some queueing methods such as [IEEE802.1Qch-2017] it is With some queueing methods such as [IEEE802.1Qch-2017] it is
possible to introduce dummy traffic in order to regularize the possible to introduce dummy traffic in order to regularize the
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Description Description
With some queueing methods such as [IEEE802.1Qch-2017] it is With some queueing methods such as [IEEE802.1Qch-2017] it is
possible to introduce dummy traffic in order to regularize the possible to introduce dummy traffic in order to regularize the
timing of packet transmission. timing of packet transmission.
Related attacks Related attacks
Removing distinctive temporal properties of individual packets or Removing distinctive temporal properties of individual packets or
flows can be used to mitigate against reconnaissance attacks flows can be used to mitigate against reconnaissance attacks
Section 5.2.6. Section 5.2.6. For example, dummy traffic can be used to
synthetically maintain constant traffic rate even when no user
data is transmitted, thus making it difficult to collect
information about the times at which users are active, and the
times at which DETNET flows are added or removed.
7.5. Encryption 7.5. Encryption
Description Description
DetNet flows can in principle be forwarded in encrypted form at Reconnaissance attacks (Section 5.2.6) can be mitigated by using
the DetNet layer, however, regarding encryption of IP headers see encryption. Specific encryption protocols will depend on the
Section 9. lower layers that DetNet is forwarded over. For example, IP flows
may be forwarded over IPsec [RFC4301], and Ethernet flows may be
secured using MACsec [IEEE802.1AE-2018].
DetNet nodes do not have any need to inspect the payload of any DetNet nodes do not have any need to inspect the payload of any
DetNet packets, making them data-agnostic. This means that end- DetNet packets, making them data-agnostic. This means that end-
to- end encryption at the application layer is an acceptable way to-end encryption at the application layer is an acceptable way to
to protect user data. protect user data.
Encryption can also be applied at the subnet layer, for example Note that reconnaissance is a threat that is not specific to
for Ethernet using MACSec, as noted in Section 9. DetNet flows, and therefore reconnaissance mitigation will
typically be analyzed and addressed by a network operator
regardless of whether DetNet flows are deployed. Thus, encryption
requirements will typically not be defined in DetNet technology-
specific specifications, but considerations of using DetNet in
encrypted environments will be discussed in these specifications.
For example, Section 5.1.2.3. of [RFC8939] discusses flow
identification of DetNet flows running over IPsec.
Related attacks Related attacks
Encryption can be used to mitigate recon attacks (Section 5.2.6). As noted above, encryption can be used to mitigate reconnaissance
However, for a DetNet network to give differentiated quality of attacks ( Section 5.2.6). However, for a DetNet to provide
service on a flow-by-flow basis, the network must be able to differentiated quality of service on a flow-by-flow basis, the
identify the flows individually. This implies that in a recon network must be able to identify the flows individually. This
attack the attacker may also be able to track individual flows to implies that in a reconnaissance attack the attacker may also be
learn more about the system. able to track individual flows to learn more about the system.
7.5.1. Encryption Considerations for DetNet 7.5.1. Encryption Considerations for DetNet
Any compute time which is required for encryption and decryption Any compute time which is required for encryption and decryption
processing ('crypto') must be included in the flow latency processing ('crypto') must be included in the flow latency
calculations. Thus, crypto algorithms used in a DetNet must have calculations. Thus, crypto algorithms used in a DetNet must have
bounded worst-case execution times, and these values must be used in bounded worst-case execution times, and these values must be used in
the latency calculations. the latency calculations.
Some crypto algorithms are symmetric in encode/decode time (such as Some crypto algorithms are symmetric in encode/decode time (such as
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timing implications of crypto for DetNet; it is assumed that timing implications of crypto for DetNet; it is assumed that
integrity considerations are covered elsewhere in the literature. integrity considerations are covered elsewhere in the literature.
Asymmetrical crypto is typically not used in networks on a packet-by- Asymmetrical crypto is typically not used in networks on a packet-by-
packet basis due to its computational cost. For example, if only packet basis due to its computational cost. For example, if only
endpoint checks or checks at a small number of intermediate points endpoint checks or checks at a small number of intermediate points
are required, asymmetric crypto can be used to authenticate are required, asymmetric crypto can be used to authenticate
distribution or exchange of a secret symmetric crypto key; a distribution or exchange of a secret symmetric crypto key; a
successful check based on that key will provide traffic origin successful check based on that key will provide traffic origin
verification, as long as the key is kept secret by the participants. verification, as long as the key is kept secret by the participants.
TLS and IKE (for IPsec) are examples of this for endpoint checks. TLS (v1.3 [RFC8446], in particular section 4.1 "Key exchange") and
IKEv2 [RFC6071]) are examples of this for endpoint checks.
However, if secret symmetrical keys are used for this purpose the key However, if secret symmetric keys are used for this purpose the key
must be given to all relays, which increases the probability of a must be given to all relays, which increases the probability of a
secret key being leaked. Also, if any relay is compromised or secret key being leaked. Also, if any relay is compromised or faulty
misbehaving it may inject traffic into the flow. then it may inject traffic into the flow. Group key management
protocols can be used to automate management of such symmetric keys;
for an example in the context of IPsec, see
[I-D.ietf-ipsecme-g-ikev2].
Alternatively, asymmetric crypto can provide traffic origin Alternatively, asymmetric crypto can provide traffic origin
verification at every intermediate node. For example, a DetNet flow verification at every intermediate node. For example, a DetNet flow
can be associated with an (asymmetric) keypair, such that the private can be associated with an (asymmetric) keypair, such that the private
key is available to the source of the flow and the public key is key is available to the source of the flow and the public key is
distributed with the flow information, allowing verification at every distributed with the flow information, allowing verification at every
node for every packet. However, this is more computationally node for every packet. However, this is more computationally
expensive. expensive.
In either case, origin verification also requires replay detection as In either case, origin verification also requires replay detection as
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forwarding resources. forwarding resources.
If crypto keys are to be regenerated over the duration of the flow If crypto keys are to be regenerated over the duration of the flow
then the time required to accomplish this must be accounted for in then the time required to accomplish this must be accounted for in
the latency calculations. the latency calculations.
7.6. Control and Signaling Message Protection 7.6. Control and Signaling Message Protection
Description Description
Control and sigaling messages can be protected using Control and signaling messages can be protected through the use of
authentication and integrity protection mechanisms. any or all of encryption, authentication, and integrity protection
mechanisms.
Related attacks Related attacks
These mechanisms can be used to mitigate various attacks on the These mechanisms can be used to mitigate various attacks on the
controller plane, as described in Section 5.2.5, Section 5.2.7 and controller plane, as described in Section 5.2.5, Section 5.2.7 and
Section 5.2.5.1. Section 5.2.5.1.
7.7. Dynamic Performance Analytics 7.7. Dynamic Performance Analytics
Description Description
The expectation is that the network will have a way to monitor to Incorporating Dynamic Performance Analytics ("DPA") implies that
detect if timing guarantees are not being met, and a way to alert the DetNet design includes a performance monitoring system to
the controller plane in that event. Information about the network validate that timing guarantees are being met and to detect timing
performance can be gathered in real-time in order to detect violations or other anomalies that may be the symptom of a
anomalies and unusual behavior that may be the symptom of a security attack or system malfunction. If this monitoring system
security attack. The gathered information can be based, for detects unexpected behavior, it must then cause action to be
example, on per-flow counters, bandwidth measurement, and initiated to address the situation in an appropriate and timely
monitoring of packet arrival times. Unusual behavior or manner, either at the data plane or controller plane, or both in
potentially malicious nodes can be reported to a management concert.
system, or can be used as a trigger for taking corrective actions.
The information can be tracked by DetNet end systems and transit
nodes, and exported to a management system, for example using
YANG.
If the monitoring or reporting mechanism itself is attacked or The overall DPA system can thus be decomposed into the "detection"
subverted, this can result in malfunction of the network. The and "notification" functions. Although the time-specific DPA
design of the monitoring system needs to take this into account performance indicators and their implementation will likely be
based on the specifics of the monitoring or reporting system being specific to a given DetNet, and as such are nascent technology at
considered. the time of this writing, DPA is commonly used in existing
networks so we can make some observations on how such a system
might be implemented for a DetNet, given that it would need to be
adapted to address the time-specific performance indicators.
Detection Mechanisms
Measurement of timing performance can be done via "passive" or
"active" monitoring, as discussed below.
Examples of passive monitoring strategies include
* Monitoring of queue and buffer levels, e.g. via Active Queue
Management (e.g. [RFC7567]
* Monitoring of per-flow counters
* Measurement of link statistics such as traffic volume,
bandwidth, and QoS
* Detection of dropped packets
* Use of commercially available Network Monitoring tools
Examples of active monitoring include
* In-band timing measurements (such as packet arrival times) e.g.
by timestamping and packet inspection
* Use of OAM. For DetNet-specific OAM considerations see
[I-D.ietf-detnet-ip-oam], [I-D.ietf-detnet-mpls-oam]. Note: At
the time of this writing, specifics of DPA have not been
developed for the DetNet OAM, but could be a subject for future
investigation
* For OAM for Ethernet specifically, see also Connectivity Fault
Management (CFM, [IEEE802.1Q]) which defines protocols and
practices for OAM for paths through 802.1 bridges and LANs
* Out-of-band detection. following the data path or parts of a
data path, for example Bidirectional Forwarding Detection (BFD,
e.g. [RFC5880])
Note that for some measurements (e.g. packet delay) it may be
necessary to make and reconcile measurements from more than one
physical location (e.g. a source and destination), possibly in
both directions, in order to arrive at a given performance
indicator value.
Notification Mechanisms
Making DPA measurement results available at the right place(s) and
time(s) to effect timely response can be challenging. Two
notification mechanisms that are in general use are Netconf/YANG
Notifications (e.g. [RFC5880]) and the proprietary local
telemetry interfaces provided with components from some vendors.
At the time of this writing YANG Notifications are not addressed
by the DetNet YANG drafts, however this may be a topic for future
work. It is possible that some of the passive mechanisms could be
covered by notifications from non-DetNet-specific YANG modules;
for example if there is OAM or other performance monitoring that
can monitor delay bounds then that could have its own associated
YANG model which could be relevant to DetNet, for example some
"threshold" values for timing measurement notifications.
At the time of this writing there is an IETF Working Group for
network/performance monitoring (IP Performance Measurement, ippm).
See also previous work by the completed Remote Network Monitoring
Working Group (rmonmib). See also [RFC6632], An Overview of the
IETF Network Management Standards.
Vendor-specific local telemetry may be available on some
commercially available systems, whereby the system can be
programmed (via a proprietary dedicated port and API) to monitor
and report on specific conditions, based on both passive and
active measurements.
Related attacks Related attacks
Performance analytics can be used to mitigate various attacks, Performance analytics can be used to mitigate various attacks,
including the ones described in Section 5.2.1 (Delay Attack), including the ones described in Section 5.2.1 (Delay Attack),
Section 5.2.3 (Resource Segmentation Attack), and Section 5.2.7 Section 5.2.3 (Resource Segmentation Attack), and Section 5.2.7
(Time Sync Attack). (Time Synchronization Attack).
For example, in the case of data plane delay attacks, one possible For example, in the case of data plane delay attacks, one possible
mitigation is to timestamp the data at the source, and timestamp mitigation is to timestamp the data at the source, and timestamp
it again at the destination, and if the resulting latency exceeds it again at the destination, and if the resulting latency exceeds
the promised bound, discard that data and warn the operator (and/ the promised bound, take appropriate action. Note that DetNet
or enter a fail-safe mode). Note that DetNet specifies packet specifies packet sequence numbering, however it does not specify
sequence numbering, however it does not specify use of packet use of packet timestamps, although they may be used by the
timestamps, although they may be used by the underlying transport underlying transport (for example TSN, [IEEE802.1BA]) to provide
(for example TSN) to provide the service. the service.
7.8. Mitigation Summary 7.8. Mitigation Summary
The following table maps the attacks of Section 5, Security Threats, The following table maps the attacks of Section 5, Security Threats,
to the impacts of Section 6, Security Threat Impacts, and to the to the impacts of Section 6, Security Threat Impacts, and to the
mitigations of the current section. Each row specifies an attack, mitigations of the current section. Each row specifies an attack,
the impact of this attack if it is successfully implemented, and the impact of this attack if it is successfully implemented, and
possible mitigation methods. possible mitigation methods.
+----------------------+---------------------+---------------------+ +----------------------+---------------------+---------------------+
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| |-Non-deterministic | | | |-Non-deterministic | |
| | delay | | | | delay | |
| |-Data disruption | | | |-Data disruption | |
+----------------------+---------------------+---------------------+ +----------------------+---------------------+---------------------+
|Control or Signaling |-Increased resource |-Control message | |Control or Signaling |-Increased resource |-Control message |
|Packet Injection | consumption | protection | |Packet Injection | consumption | protection |
| |-Non-deterministic | | | |-Non-deterministic | |
| | delay | | | | delay | |
| |-Data disruption | | | |-Data disruption | |
+----------------------+---------------------+---------------------+ +----------------------+---------------------+---------------------+
|Attacks on Time Sync |-Non-deterministic |-Path redundancy | |Attacks on Time |-Non-deterministic |-Path redundancy |
|Mechanisms | delay |-Control message | |Synchronization | delay |-Control message |
| |-Increased resource | protection | |Mechanisms |-Increased resource | protection |
| | consumption |-Performance | | | consumption |-Performance |
| |-Data disruption | analytics | | |-Data disruption | analytics |
+----------------------+---------------------+---------------------+ +----------------------+---------------------+---------------------+
Figure 3: Mapping Attacks to Impact and Mitigations Figure 3: Mapping Attacks to Impact and Mitigations
8. Association of Attacks to Use Cases 8. Association of Attacks to Use Cases
Different attacks can have different impact and/or mitigation Different attacks can have different impact and/or mitigation
depending on the use case, so we would like to make this association depending on the use case, so we would like to make this association
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A DetNet network can be controlled by a centralized network A DetNet network can be controlled by a centralized network
configuration and control system. Such a system may be in a single configuration and control system. Such a system may be in a single
central location, or it may be distributed across multiple control central location, or it may be distributed across multiple control
entities that function together as a unified control system for the entities that function together as a unified control system for the
network. network.
All attacks named in this document which are relevant to controller All attacks named in this document which are relevant to controller
plane packets (and the controller itself) are relevant to this theme, plane packets (and the controller itself) are relevant to this theme,
including Path Manipulation, Path Choice, Control Packet Modification including Path Manipulation, Path Choice, Control Packet Modification
or Injection, Reconaissance and Attacks on Time Sync Mechanisms. or Injection, Reconaissance and Attacks on Time Synchronization
Mechanisms.
8.1.3. Hot Swap 8.1.3. Hot Swap
A DetNet network is not expected to be "plug and play" - it is A DetNet network is not expected to be "plug and play" - it is
expected that there is some centralized network configuration and expected that there is some centralized network configuration and
control system. However, the ability to "hot swap" components (e.g. control system. However, the ability to "hot swap" components (e.g.
due to malfunction) is similar enough to "plug and play" that this due to malfunction) is similar enough to "plug and play" that this
kind of behavior may be expected in DetNet networks, depending on the kind of behavior may be expected in DetNet networks, depending on the
implementation. implementation.
An attack surface related to Hot Swap is that the DetNet network must An attack surface related to Hot Swap is that the DetNet network must
at least consider input at runtime from devices that were not part of at least consider input at runtime from components that were not part
the initial configuration of the network. Even a "perfect" (or of the initial configuration of the network. Even a "perfect" (or
"hitless") replacement of a device at runtime would not necessarily "hitless") replacement of a component at runtime would not
be ideal, since presumably one would want to distinguish it from the necessarily be ideal, since presumably one would want to distinguish
original for OAM purposes (e.g. to report hot swap of a failed it from the original for OAM purposes (e.g. to report hot swap of a
device). failed component).
This implies that an attack such as Flow Modification, Spoofing or This implies that an attack such as Flow Modification, Spoofing or
Inter-segment (which could introduce packets from a "new" device Inter-segment (which could introduce packets from a "new" component,
(i.e. one heretofore unknown on the network) could be used to exploit i.e. one heretofore unknown on the network) could be used to exploit
the need to consider such packets (as opposed to rejecting them out the need to consider such packets (as opposed to rejecting them out
of hand as one would do if one did not have to consider introduction of hand as one would do if one did not have to consider introduction
of a new device). of a new component).
To mitigate this situation, deployments should provide a method for
dynamic and secure registration of new components, and (possibly
manual) deregistration of retired components. This would avoid the
situation in which the network must accommodate potentially insecure
packet flows from unknown components.
Similarly if the network was designed to support runtime replacement Similarly if the network was designed to support runtime replacement
of a clock device, then presence (or apparent presence) and thus of a clock component, then presence (or apparent presence) and thus
consideration of packets from a new such device could affect the consideration of packets from a new such component could affect the
network, or the time sync of the network, for example by initiating a network, or the time synchronization of the network, for example by
new Best Master Clock selection process. Thus attacks on time sync initiating a new Best Master Clock selection process. These types of
should be considered when designing hot swap type functionality (see attacks should therefore be considered when designing hot swap type
[RFC7384]). functionality (see [RFC7384]).
8.1.4. Data Flow Information Models 8.1.4. Data Flow Information Models
Data Flow YANG models specific to DetNet networks are specified by DetNet specifies new YANG models which may present new attack
DetNet, and thus are 'new' and thus potentially present a new attack surfaces. Per IETF guidelines, security considerations for any YANG
surface. model are expected to be part of the YANG model specification, as
described in [IETF_YANG_SEC].
8.1.5. L2 and L3 Integration 8.1.5. L2 and L3 Integration
A DetNet network integrates Layer 2 (bridged) networks (e.g. AVB/TSN A DetNet network integrates Layer 2 (bridged) networks (e.g. AVB/TSN
LAN) and Layer 3 (routed) networks via the use of well-known LAN) and Layer 3 (routed) networks (e.g. IP) via the use of well-
protocols such as IP, MPLS Pseudowire, and Ethernet. known protocols such as IP, MPLS Pseudowire, and Ethernet. Various
DetNet drafts address many specific aspects of Layer 2 and Layer 3
integration within a DetNet, and these are not individually
referenced here; security considerations for those aspects are
covered within those drafts or within the related subsections of the
present document.
There are no specific entries in the mapping table Figure 4, however Please note that although there are no entries in the L2 and L3
that does not imply that there could be no relevant attacks related Integration line of the Mapping Between Themes and Attacks table
to L2-L3 integration. Figure 4, this does not imply that there could be no relevant attacks
related to L2-L3 integration.
8.1.6. End-to-End Delivery 8.1.6. End-to-End Delivery
Packets sent over DetNet are not to be dropped by the network due to Packets sent over DetNet are not to be dropped by the network due to
congestion. (Packets may however intentionally be dropped for congestion. (Packets may however intentionally be dropped for
intended reasons, e.g. per security measures). intended reasons, e.g. per security measures).
A data plane attack may force packets to be dropped, for example a A data plane attack may force packets to be dropped, for example a
"long" Delay or Replication/Elimination or Flow Modification attack. "long" Delay or Replication/Elimination or Flow Modification attack.
The same result might be obtained by a controller plane attack, e.g. The same result might be obtained by a controller plane attack, e.g.
Path Manipulation or Signaling Packet Modification. Path Manipulation or Signaling Packet Modification.
It may be that such attacks are limited to Internal on-path It may be that such attacks are limited to Internal on-path
attackers, but other possibilities should be considered. attackers, but other possibilities should be considered.
An attack may also cause packets that should not be delivered to be An attack may also cause packets that should not be delivered to be
delivered, such as by forcing packets from one (e.g. replicated) path delivered, such as by forcing packets from one (e.g. replicated) path
to be preferred over another path when they should not be to be preferred over another path when they should not be
(Replication attack), or by Flow Modification, or by Path Choice or (Replication attack), or by Flow Modification, or by Path Choice or
Packet Injection. A Time Sync attack could cause a system that was Packet Injection. A Time Synchronization attack could cause a system
expecting certain packets at certain times to accept unintended that was expecting certain packets at certain times to accept
packets based on compromised system time or time windowing in the unintended packets based on compromised system time or time windowing
scheduler. in the scheduler.
8.1.7. Replacement for Proprietary Fieldbuses and Ethernet-based 8.1.7. Replacement for Proprietary Fieldbuses and Ethernet-based
Networks Networks
There are many proprietary "field buses" used in today's industrial There are many proprietary "field buses" used in Industrial and other
and other industries, as well as proprietary non-interoperable industries, as well as proprietary non-interoperable deterministic
deterministic Ethernet-based networks. DetNet is intended to provide Ethernet-based networks. DetNet is intended to provide an open-
an open-standards-based alternative to such buses/networks. In cases standards-based alternative to such buses/networks. In cases where a
where a DetNet intersects with such fieldbuses/networks or their DetNet intersects with such fieldbuses/networks or their protocols,
protocols, such as by protocol emulation or access via a gateway, new such as by protocol emulation or access via a gateway, new attack
attack surfaces can be opened. surfaces can be opened.
For example an Inter-Segment or Controller plane attack such as Path For example an Inter-Segment or Controller plane attack such as Path
Manipulation, Path Choice or Control Packet Modification/Injection Manipulation, Path Choice or Control Packet Modification/Injection
could be used to exploit commands specific to such a protocol, or could be used to exploit commands specific to such a protocol, or
that are interpreted differently by the different protocols or that are interpreted differently by the different protocols or
gateway. gateway.
8.1.8. Deterministic vs Best-Effort Traffic 8.1.8. Deterministic vs Best-Effort Traffic
Most of the themes described in this document address OT (reserved) Most of the themes described in this document address OT (reserved)
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open Internet, however this aspect of DetNet security should not be open Internet, however this aspect of DetNet security should not be
underestimated. underestimated.
An Inter-segment attack can flood the network with IT-type traffic An Inter-segment attack can flood the network with IT-type traffic
with the intent of disrupting handling of IT traffic, and/or the goal with the intent of disrupting handling of IT traffic, and/or the goal
of interfering with OT traffic. Presumably if the DetNet flow of interfering with OT traffic. Presumably if the DetNet flow
reservation and isolation of the DetNet is well-designed (better- reservation and isolation of the DetNet is well-designed (better-
designed than the attack) then interference with OT traffic should designed than the attack) then interference with OT traffic should
not result from an attack that floods the network with IT traffic. not result from an attack that floods the network with IT traffic.
However the DetNet's handling of IT traffic may not (by design) be as However the handling of IT traffic by the DetNet may not (by design)
resilient to DOS attack, and thus designers must be otherwise be as resilient to DOS attack, and thus designers must be otherwise
prepared to mitigate DOS attacks on IT traffic in a DetNet. prepared to mitigate DOS attacks on IT traffic in a DetNet.
The network design as a whole also needs to consider possible
application-level dependencies of "OT"-type applications on services
provided by the "IT part" of the network; for example, does the OT
application depend on IT network services such as DNS or OAM? If
such dependencies exist, how are malicious packet flows handled?
Such considerations are typically outside the scope of DetNet proper,
but nonetheless need to be addressed in the overall DetNet network
design for a given use case.
8.1.9. Deterministic Flows 8.1.9. Deterministic Flows
Reserved bandwidth data flows (deterministic flows) must provide the Reserved bandwidth data flows (deterministic flows) must provide the
allocated bandwidth, and must be isolated from each other. allocated bandwidth, and must be isolated from each other.
A Spoofing or Inter-segment attack which adds packet traffic to a A Spoofing or Inter-segment attack which adds packet traffic to a
bandwidth-reserved DetNet flow could cause that flow to occupy more bandwidth-reserved DetNet flow could cause that flow to occupy more
bandwidth than it was allocated, resulting in interference with other bandwidth than it was allocated, resulting in interference with other
DetNet flows. DetNet flows.
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associated bandwidth is not used at any point in time, that bandwidth associated bandwidth is not used at any point in time, that bandwidth
is made available on the network for best-effort traffic. However, is made available on the network for best-effort traffic. However,
note that security considerations for best-effort traffic on a DetNet note that security considerations for best-effort traffic on a DetNet
network is out of scope of the present document, provided that such network is out of scope of the present document, provided that such
an attack does not affect performance for DetNet OT traffic. an attack does not affect performance for DetNet OT traffic.
8.1.11. Interoperability 8.1.11. Interoperability
The DetNet network specifications are intended to enable an ecosystem The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus in which multiple vendors can create interoperable products, thus
promoting device diversity and potentially higher numbers of each promoting component diversity and potentially higher numbers of each
device manufactured. component manufactured.
The security mechanisms and protocols that are discussed in this
document also require interoperability. It is expected that DETNET
network specifications that define security measures and protocols
will be defined in a way that allows interoperability.
Given that the DetNet specifications are unambiguously written and Given that the DetNet specifications are unambiguously written and
that the implementations are accurate, then this should not in and of that the implementations are accurate, then this should not in and of
itself cause a security concern; however, in the real world, it could itself cause a security concern; however, in the real world, it could
be. The network operator can mitigate this through sufficient be. The network operator can mitigate this through sufficient
interoperability testing. interoperability testing.
8.1.12. Cost Reductions 8.1.12. Cost Reductions
The DetNet network specifications are intended to enable an ecosystem The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus in which multiple vendors can create interoperable products, thus
promoting higher numbers of each device manufactured, promoting cost promoting higher numbers of each component manufactured, promoting
reduction and cost competition among vendors. cost reduction and cost competition among vendors.
This envisioned breadth of DetNet-enabled products is in general a This envisioned breadth of DetNet-enabled products is in general a
positive factor, however implementation flaws in any individual positive factor, however implementation flaws in any individual
component can present an attack surface. In addition, implementation component can present an attack surface. In addition, implementation
differences between components from different vendors can result in differences between components from different vendors can result in
attack surfaces (resulting from their interaction) which may not attack surfaces (resulting from their interaction) which may not
exist in any individual component. exist in any individual component.
Network operators can mitigate such concerns through sufficient Network operators can mitigate such concerns through sufficient
product and interoperability testing. product and interoperability testing.
8.1.13. Insufficiently Secure Devices 8.1.13. Insufficiently Secure Components
The DetNet network specifications are intended to enable an ecosystem The DetNet network specifications are intended to enable an ecosystem
in which multiple vendors can create interoperable products, thus in which multiple vendors can create interoperable products, thus
promoting device diversity and potentially higher numbers of each promoting component diversity and potentially higher numbers of each
device manufactured. However this raises the possibility that a component manufactured. However this raises the possibility that a
vendor might repurpose for DetNet applications a hardware or software vendor might repurpose for DetNet applications a hardware or software
component that was originally designed for operation in an isolated component that was originally designed for operation in an isolated
OT network, and thus may not have been designed to be sufficiently OT network, and thus may not have been designed to be sufficiently
secure, or secure at all. Deployment of such a device on a DetNet secure, or secure at all. Deployment of such a component on a DetNet
network that is intended to be highly secure may present an attack network that is intended to be highly secure may present an attack
surface. surface.
The DetNet network operator may need to take specific actions to The DetNet network operator may need to take specific actions to
protect such devices, such as implementing a dedicated security layer protect such components, such as implementing a dedicated security
around the device. layer around the component.
8.1.14. DetNet Network Size 8.1.14. DetNet Network Size
DetNet networks range in size from very small, e.g. inside a single DetNet networks range in size from very small, e.g. inside a single
industrial machine, to very large, for example a Utility Grid network industrial machine, to very large, for example a Utility Grid network
spanning a whole country. spanning a whole country.
The size of the network might be related to how the attack is The size of the network might be related to how the attack is
introduced into the network, for example if the entire network is introduced into the network, for example if the entire network is
local, there is a threat that power can be cut to the entire network. local, there is a threat that power can be cut to the entire network.
If the network is large, perhaps only a part of the network is If the network is large, perhaps only a part of the network is
attacked. attacked.
A Delay attack might be as relevant to a small network as to a large A Delay attack might be as relevant to a small network as to a large
network, although the amount of delay might be different. network, although the amount of delay might be different.
Attacks sourced from IT traffic might be more likely in large Attacks sourced from IT traffic might be more likely in large
networks, since more people might have access to the network, networks, since more people might have access to the network,
presenting a larger attack surface. Similarly Path Manipulation, presenting a larger attack surface. Similarly Path Manipulation,
Path Choice and Time Sync attacks seem more likely relevant to large Path Choice and Time Synchronization attacks seem more likely
networks. relevant to large networks.
8.1.15. Multiple Hops 8.1.15. Multiple Hops
Large DetNet networks (e.g. a Utility Grid network) may involve many Large DetNet networks (e.g. a Utility Grid network) may involve many
"hops" over various kinds of links for example radio repeaters, "hops" over various kinds of links for example radio repeaters,
microwave links, fiber optic links, etc. microwave links, fiber optic links, etc.
An attack that takes advantage of flaws (or even normal operation) in An attack that takes advantage of flaws (or even normal operation) in
the device drivers for the various links (through internal knowledge the device drivers for the various links (through internal knowledge
of how the individual driver or firmware operates) could take of how the individual driver or firmware operates) could take
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latency for a given path or DetNet flow, and so on. It is an latency for a given path or DetNet flow, and so on. It is an
expected case that the network cannot provide a given requested expected case that the network cannot provide a given requested
service level. In such cases the network control system should reply service level. In such cases the network control system should reply
that the requested service level is not available (as opposed to that the requested service level is not available (as opposed to
accepting the parameter but then not delivering the desired accepting the parameter but then not delivering the desired
behavior). behavior).
Controller plane attacks such as Signaling Packet Modification and Controller plane attacks such as Signaling Packet Modification and
Injection could be used to modify or create control traffic that Injection could be used to modify or create control traffic that
could interfere with the process of a user requesting a level of could interfere with the process of a user requesting a level of
service and/or the network's reply. service and/or the reply from the network.
Reconnaissance could be used to characterize flows and perhaps target Reconnaissance could be used to characterize flows and perhaps target
specific flows for attack via the controller plane as noted in specific flows for attack via the controller plane as noted in
Section 6.7. Section 6.7.
8.1.17. Bounded Latency 8.1.17. Bounded Latency
DetNet provides the expectation of guaranteed bounded latency. DetNet provides the expectation of guaranteed bounded latency.
Delay attacks can cause packets to miss their agreed-upon latency Delay attacks can cause packets to miss their agreed-upon latency
boundaries. boundaries.
Time Sync attacks can corrupt the system's time reference, resulting Time Synchronization attacks can corrupt the time reference of the
in missed latency deadlines (with respect to the "correct" time system, resulting in missed latency deadlines (with respect to the
reference). "correct" time reference).
8.1.18. Low Latency 8.1.18. Low Latency
Applications may require "extremely low latency" however depending on Applications may require "extremely low latency" however depending on
the application these may mean very different latency values; for the application these may mean very different latency values; for
example "low latency" across a Utility grid network is on a different example "low latency" across a Utility grid network is on a different
time scale than "low latency" in a motor control loop in a small time scale than "low latency" in a motor control loop in a small
machine. The intent is that the mechanisms for specifying desired machine. The intent is that the mechanisms for specifying desired
latency include wide ranges, and that architecturally there is latency include wide ranges, and that architecturally there is
nothing to prevent arbitrarily low latencies from being implemented nothing to prevent arbitrarily low latencies from being implemented
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the jitter specification. the jitter specification.
8.1.20. Symmetrical Path Delays 8.1.20. Symmetrical Path Delays
Some applications would like to specify that the transit delay time Some applications would like to specify that the transit delay time
values be equal for both the transmit and return paths. values be equal for both the transmit and return paths.
Delay attacks can cause path delays to materially differ between Delay attacks can cause path delays to materially differ between
paths. paths.
Time Sync attacks can corrupt the system's time reference, resulting Time Synchronization attacks can corrupt the time reference of the
in path delays that may be perceived to be different (with respect to system, resulting in path delays that may be perceived to be
the "correct" time reference) even if they are not materially different (with respect to the "correct" time reference) even if they
different. are not materially different.
8.1.21. Reliability and Availability 8.1.21. Reliability and Availability
DetNet based systems are expected to be implemented with essentially DetNet based systems are expected to be implemented with essentially
arbitrarily high availability (for example 99.9999% up time, or even arbitrarily high availability (for example 99.9999% up time, or even
12 nines). The intent is that the DetNet designs should not make any 12 nines). The intent is that the DetNet designs should not make any
assumptions about the level of reliability and availability that may assumptions about the level of reliability and availability that may
be required of a given system, and should define parameters for be required of a given system, and should define parameters for
communicating these kinds of metrics within the network. communicating these kinds of metrics within the network.
Any attack on the system, of any type, can affect its overall Any attack on the system, of any type, can affect its overall
reliability and availability, thus in the mapping table Figure 4 we reliability and availability, thus in the mapping table Figure 4 we
have marked every attack. Since every DetNet depends to a greater or have marked every attack. Since every DetNet depends to a greater or
lesser degree on reliability and availability, this essentially means lesser degree on reliability and availability, this essentially means
that all networks have to mitigate all attacks, which to a greater or that all networks have to mitigate all attacks, which to a greater or
lesser degree defeats the purpose of associating attacks with use lesser degree defeats the purpose of associating attacks with use
cases. It also underscores the difficulty of designing "extremely cases. It also underscores the difficulty of designing "extremely
high reliability" networks. high reliability" networks.
In practice, network designers can adopt a risk-based approach, in
which only those attacks are mitigated whose potential cost is higher
than the cost of mitigation.
8.1.22. Redundant Paths 8.1.22. Redundant Paths
DetNet based systems are expected to be implemented with essentially DetNet based systems are expected to be implemented with essentially
arbitrarily high reliability/availability. A strategy used by DetNet arbitrarily high reliability/availability. A strategy used by DetNet
for providing such extraordinarily high levels of reliability is to for providing such extraordinarily high levels of reliability is to
provide redundant paths that can be seamlessly switched between, all provide redundant paths that can be seamlessly switched between, all
the while maintaining the required performance of that system. the while maintaining the required performance of that system.
Replication-related attacks are by definition applicable here. Replication-related attacks are by definition applicable here.
Controller plane attacks can also interfere with the configuration of Controller plane attacks can also interfere with the configuration of
redundant paths. redundant paths.
8.1.23. Security Measures 8.1.23. Security Measures
A DetNet network must be made secure against devices failures, A DetNet network must be made sufficiently secure against problematic
attackers, misbehaving component, and so on. If the security component or traffic behavior, whether malicious or incidental, and
mechanisms protecting the DetNet are attacked or subverted, this can whether affecting a single component or multiple components. If any
result in malfunction of the network. The design of the security of the security mechanisms which protect the DetNet from such
system itself needs to take this into account based on the specifics problems are attacked or subverted, this can result in malfunction of
of the security system being considered. The general topic of the network. Thus the design of the security system itself needs to
protection of security mechanisms is not unique to DetNet; it is be robust against attacks.
identical to the case of securing any security mechanism for any
network. The text of this document addresses these concerns to the The general topic of protection of security mechanisms is not unique
extent that they are relevant to DetNet. to DetNet; it is identical to the case of securing any security
mechanism for any network. This document addresses these concerns
only to the extent that they are unique to DetNet.
8.2. Summary of Attack Types per Use Case Common Theme 8.2. Summary of Attack Types per Use Case Common Theme
The List of Attacks table Figure 4 lists the attacks of Section 5, The List of Attacks table Figure 4 lists the attacks of Section 5,
Security Threats, assigning a number to each type of attack. That Security Threats, assigning a number to each type of attack. That
number is then used as a short form identifier for the attack in number is then used as a short form identifier for the attack in
Figure 5, Mapping Between Themes and Attacks. Figure 5, Mapping Between Themes and Attacks.
+----+----------------------------------------+ +----+-------------------------------------------+
| | Attack | | | Attack |
+----+----------------------------------------+ +----+-------------------------------------------+
| 1 |Delay Attack | | 1 |Delay Attack |
+----+----------------------------------------+ +----+-------------------------------------------+
| 2 |DetNet Flow Modification or Spoofing | | 2 |DetNet Flow Modification or Spoofing |
+----+----------------------------------------+ +----+-------------------------------------------+
| 3 |Inter-Segment Attack | | 3 |Inter-Segment Attack |
+----+----------------------------------------+ +----+-------------------------------------------+
| 4 |Replication: Increased attack surface | | 4 |Replication: Increased attack surface |
+----+----------------------------------------+ +----+-------------------------------------------+
| 5 |Replication-related Header Manipulation | | 5 |Replication-related Header Manipulation |
+----+----------------------------------------+ +----+-------------------------------------------+
| 6 |Path Manipulation | | 6 |Path Manipulation |
+----+----------------------------------------+ +----+-------------------------------------------+
| 7 |Path Choice: Increased Attack Surface | | 7 |Path Choice: Increased Attack Surface |
+----+----------------------------------------+ +----+-------------------------------------------+
| 8 |Control or Signaling Packet Modification| | 8 |Control or Signaling Packet Modification |
+----+----------------------------------------+ +----+-------------------------------------------+
| 9 |Control or Signaling Packet Injection | | 9 |Control or Signaling Packet Injection |
+----+----------------------------------------+ +----+-------------------------------------------+
| 10 |Reconnaissance | | 10 |Reconnaissance |
+----+----------------------------------------+ +----+-------------------------------------------+
| 11 |Attacks on Time Sync Mechanisms | | 11 |Attacks on Time Synchronization Mechanisms |
+--+----------------------------------------+ +----+-------------------------------------------+
Figure 4: List of Attacks Figure 4: List of Attacks
The Mapping Between Themes and Attacks table Figure 5 maps the use The Mapping Between Themes and Attacks table Figure 5maps the use
case themes of [RFC8578] (as also enumerated in this document) to the case themes of [RFC8578] (as also enumerated in this document) to the
attacks of Figure 4. Each row specifies a theme, and the attacks attacks of Figure 4. Each row specifies a theme, and the attacks
relevant to this theme are marked with a '+'. The row items which relevant to this theme are marked with a '+'. The row items which
have no threats associated with them are included in the table for have no threats associated with them are included in the table for
completeness of the list of Use Case Common Themes, and do not have completeness of the list of Use Case Common Themes, and do not have
DetNet-specific threats associated with them. DetNet-specific threats associated with them.
+----------------------------+--------------------------------+ +----------------------------+--------------------------------+
| Theme | Attack | | Theme | Attack |
| +--+--+--+--+--+--+--+--+--+--+--+ | +--+--+--+--+--+--+--+--+--+--+--+
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+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Deterministic Flows | | +| +| | +| +| | +| | | | |Deterministic Flows | | +| +| | +| +| | +| | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Unused Reserved Bandwidth | | +| +| | | | | +| +| | | |Unused Reserved Bandwidth | | +| +| | | | | +| +| | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Interoperability | | | | | | | | | | | | |Interoperability | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Cost Reductions | | | | | | | | | | | | |Cost Reductions | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Insufficiently Secure | | | | | | | | | | | | |Insufficiently Secure | | | | | | | | | | | |
|Devices | | | | | | | | | | | | |Components | | | | | | | | | | | |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|DetNet Network Size | +| | | | | +| +| | | | +| |DetNet Network Size | +| | | | | +| +| | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Multiple Hops | +| +| | | | +| +| | | | +| |Multiple Hops | +| +| | | | +| +| | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Level of Service | | | | | | | | +| +| +| | |Level of Service | | | | | | | | +| +| +| |
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Bounded Latency | +| | | | | | | | | | +| |Bounded Latency | +| | | | | | | | | | +|
+----------------------------+--+--+--+--+--+--+--+--+--+--+--+ +----------------------------+--+--+--+--+--+--+--+--+--+--+--+
|Low Latency | +| | | | | | | +| +| +| +| |Low Latency | +| | | | | | | +| +| +| +|
skipping to change at page 39, line 47 skipping to change at page 44, line 12
specifically related to the IP- and MPLS-specific aspects of DetNet specifically related to the IP- and MPLS-specific aspects of DetNet
implementations. implementations.
The primary security considerations for the data plane specifically The primary security considerations for the data plane specifically
are to maintain the integrity of the data and the delivery of the are to maintain the integrity of the data and the delivery of the
associated DetNet service traversing the DetNet network. associated DetNet service traversing the DetNet network.
The primary relevant differences between IP and MPLS implementations The primary relevant differences between IP and MPLS implementations
are in flow identification and OAM methodologies. are in flow identification and OAM methodologies.
As noted in [RFC8655], DetNet operates at the IP layer As noted in [RFC8655], DetNet operates at the IP layer ( [RFC8939])
([I-D.ietf-detnet-ip]) and delivers service over sub-layer and delivers service over sub-layer technologies such as MPLS
technologies such as MPLS ([I-D.ietf-detnet-mpls]) and IEEE 802.1 ([RFC8938]) and IEEE 802.1 Time-Sensitive Networking (TSN)
Time-Sensitive Networking (TSN) ([I-D.ietf-detnet-ip-over-tsn]). ([I-D.ietf-detnet-ip-over-tsn]). Application flows can be protected
Application flows can be protected through whatever means are through whatever means are provided by the layer and sub-layer
provided by the layer and sub-layer technologies. For example, technologies. For example, technology-specific encryption may be
technology-specific encryption may be used, such as that provided by used, for example for IP flows, IPSec [RFC4301]. For IP over
IPSec [RFC4301] for IP flows and/or by an underlying sub-net using Ethernet (Layer 2) flows using an underlying sub-net, MACSec
MACSec [IEEE802.1AE-2018] for IP over Ethernet (Layer-2) flows. [IEEE802.1AE-2018] may be appropriate. For some use cases packet
integrity protection without encryption may be sufficient.
However, if the DetNet nodes cannot decrypt IPsec traffic, IPSec may However, if the DetNet nodes cannot decrypt IPsec traffic, then
not be a valid option; this is because the DetNet IP Data Plane DetNet flow identification for encrypted IP traffic flows must be
identifies flows via a 6-tuple that consists of two IP addresses, the performed in a different way than it would be for unencrypted IP
transport protocol ID, two transport protocol port numbers and the DetNet flows. The DetNet IP Data Plane identifies unencrypted flows
DSCP in the IP header. When IPsec is used, the transport header is via a 6-tuple that consists of two IP addresses, the transport
encrypted and the next protocol ID is an IPsec protocol, usually ESP, protocol ID, two transport protocol port numbers and the DSCP in the
and not a transport protocol (e.g., neither TCP nor UDP, etc.) IP header. When IPsec is used, the transport header is encrypted and
leaving only three components of the 6-tuple, which are the two IP the next protocol ID is an IPsec protocol, usually ESP, and not a
addresses and the DSCP, which are in general not sufficient to transport protocol, leaving only three components of the 6-tuple,
identify a DetNet flow. which are the two IP addresses and the DSCP. Identification of
DetNet flows over IPsec is further discussed in Section 5.1.2.3. of
[RFC8939].
Sections below discuss threats specific to IP and MPLS in more Sections below discuss threats specific to IP and MPLS in more
detail. detail.
9.1. IP 9.1. IP
The IP protocol has a long history of security considerations and The IP protocol has a long history of security considerations and
architectural protection mechanisms. From a data plane perspective architectural protection mechanisms. From a data plane perspective
DetNet does not add or modify any IP header information, so the DetNet does not add or modify any IP header information, so the
carriage of DetNet traffic over an IP data plane does not introduce carriage of DetNet traffic over an IP data plane does not introduce
skipping to change at page 41, line 6 skipping to change at page 45, line 22
Another way to look at DetNet IP security is to consider it in the Another way to look at DetNet IP security is to consider it in the
light of VPN security; as an industry we have a lot of experience light of VPN security; as an industry we have a lot of experience
with VPNs running through networks with other VPNs, it is well known with VPNs running through networks with other VPNs, it is well known
how to secure the network for that. However for a DetNet we have the how to secure the network for that. However for a DetNet we have the
additional subtlety that any possible interaction of one packet with additional subtlety that any possible interaction of one packet with
another can have a potentially deleterious effect on the time another can have a potentially deleterious effect on the time
properties of the flows. So the network must provide sufficient properties of the flows. So the network must provide sufficient
isolation between flows, for example by protecting the forwarding isolation between flows, for example by protecting the forwarding
bandwidth and related resources so that they are available to detnet bandwidth and related resources so that they are available to detnet
traffic, by whatever means are appropriate for that network's data traffic, by whatever means are appropriate for the data plane of that
plane, for example through the use of queueing mechanisms. network, for example through the use of queueing mechanisms.
In a VPN, bandwidth is generally guaranteed over a period of time, In a VPN, bandwidth is generally guaranteed over a period of time,
whereas in DetNet it is not aggregated over time. This implies that whereas in DetNet it is not aggregated over time. This implies that
any VPN-type protection mechanism must also maintain the DetNet any VPN-type protection mechanism must also maintain the DetNet
timing constraints. timing constraints.
9.2. MPLS 9.2. MPLS
An MPLS network carrying DetNet traffic is expected to be a "well- An MPLS network carrying DetNet traffic is expected to be a "well-
managed" network. Given that this is the case, it is difficult for managed" network. Given that this is the case, it is difficult for
skipping to change at page 41, line 40 skipping to change at page 46, line 8
operation of DetNet over some types of MPLS network. operation of DetNet over some types of MPLS network.
[RFC5921] introduces to MPLS new Operations, Administration, and [RFC5921] introduces to MPLS new Operations, Administration, and
Maintenance (OAM) capabilities, a transport-oriented path protection Maintenance (OAM) capabilities, a transport-oriented path protection
mechanism, and strong emphasis on static provisioning supported by mechanism, and strong emphasis on static provisioning supported by
network management systems. network management systems.
The operation of DetNet over an MPLS network is modeled on the The operation of DetNet over an MPLS network is modeled on the
operation of multi-segment pseudowires (MS-PW). Thus for guidance on operation of multi-segment pseudowires (MS-PW). Thus for guidance on
securing the DetNet elements of DetNet over MPLS the reader is securing the DetNet elements of DetNet over MPLS the reader is
referred to the MS-PW security mechanisms as defined in [RFC4447], referred to the MS-PW security mechanisms as defined in [RFC8077],
[RFC3931], [RFC3985], [RFC6073], and [RFC6478]. [RFC3931], [RFC3985], [RFC6073], and [RFC6478].
Having attended to the conventional aspects of network security it is Having attended to the conventional aspects of network security it is
necessary to attend to the dynamic aspects. The closest experience necessary to attend to the dynamic aspects. The closest experience
that the IETF has with securing protocols that are sensitive to that the IETF has with securing protocols that are sensitive to
manipulation of delay are the two way time transfer protocols (TWTT), manipulation of delay are the two way time transfer protocols (TWTT),
which are NTP [RFC5905] and Precision Time Protocol [IEEE1588]. The which are NTP [RFC5905] and Precision Time Protocol [IEEE1588]. The
security requirements for these are described in [RFC7384]. security requirements for these are described in [RFC7384].
One particular problem that has been observed in operational tests of One particular problem that has been observed in operational tests of
skipping to change at page 42, line 14 skipping to change at page 46, line 30
synchronized flows to beat and cause a sudden phase hit to one of the synchronized flows to beat and cause a sudden phase hit to one of the
flows. This can be mitigated by the careful use of a scheduling flows. This can be mitigated by the careful use of a scheduling
system in the underlying packet transport. system in the underlying packet transport.
Further consideration of protection against dynamic attacks is work Further consideration of protection against dynamic attacks is work
in progress. New work on MPLS security may also be applicable, for in progress. New work on MPLS security may also be applicable, for
example [I-D.ietf-mpls-opportunistic-encrypt]. example [I-D.ietf-mpls-opportunistic-encrypt].
10. IANA Considerations 10. IANA Considerations
This memo includes no requests from IANA. This document includes no requests from IANA.
11. Security Considerations 11. Security Considerations
The security considerations of DetNet networks are presented The security considerations of DetNet networks are presented
throughout this document. throughout this document.
12. Privacy Considerations 12. Privacy Considerations
Privacy in the context of DetNet is maintained by the base Privacy in the context of DetNet is maintained by the base
technologies specific to the DetNet and user traffic. For example technologies specific to the DetNet and user traffic. For example
skipping to change at page 43, line 6 skipping to change at page 47, line 6
transport protocol-provided methods e.g. TLS and DTLS. MPLS transport protocol-provided methods e.g. TLS and DTLS. MPLS
typically uses L2/L3 VPNs combined with the previously mentioned typically uses L2/L3 VPNs combined with the previously mentioned
privacy methods. privacy methods.
13. Contributors 13. Contributors
The Editor would like to recognize the contributions of the following The Editor would like to recognize the contributions of the following
individuals to this draft. individuals to this draft.
Subir Das (Applied Communication Sciences) Subir Das (Applied Communication Sciences)
150 Mount Airy Road, Basking Ridge 150 Mount Airy Road, Basking Ridge, New Jersey, 07920, USA
New Jersey, 07920, USA
email sdas@appcomsci.com email sdas@appcomsci.com
John Dowdell (Airbus Defence and Space) John Dowdell (Airbus Defence and Space)
Celtic Springs, Newport, NP10 8FZ, United Kingdom Celtic Springs, Newport, NP10 8FZ, United Kingdom
email john.dowdell.ietf@gmail.com email john.dowdell.ietf@gmail.com
Henrik Austad (SINTEF Digital) Henrik Austad (SINTEF Digital)
Klaebuveien 153, Trondheim, 7037, Norway Klaebuveien 153, Trondheim, 7037, Norway
email henrik@austad.us email henrik@austad.us
Norman Finn Norman Finn (Huawei)
3101 Rio Way, Spring Valley, California 91977, USA
email nfinn@nfinnconsulting.com email nfinn@nfinnconsulting.com
Stewart Bryant Stewart Bryant (Futurewei Technologies)
Futurewei Technologies
email: stewart.bryant@gmail.com email: stewart.bryant@gmail.com
David Black David Black (Dell EMC)
Dell EMC
176 South Street, Hopkinton, MA 01748, USA 176 South Street, Hopkinton, MA 01748, USA
email: david.black@dell.com email: david.black@dell.com
Carsten Bormann Carsten Bormann (Universitat Bremen TZI)
Postfach 330440, D-28359 Bremen, Germany
email: cabo@tzi.org
14. References 14. References
14.1. Normative References 14.1. Normative References
[I-D.ietf-detnet-ip]
Varga, B., Farkas, J., Berger, L., Fedyk, D., and S.
Bryant, "DetNet Data Plane: IP", draft-ietf-detnet-ip-07
(work in progress), July 2020.
[I-D.ietf-detnet-mpls]
Varga, B., Farkas, J., Berger, L., Malis, A., Bryant, S.,
and J. Korhonen, "DetNet Data Plane: MPLS", draft-ietf-
detnet-mpls-12 (work in progress), September 2020.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas, [RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655, "Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019, DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>. <https://www.rfc-editor.org/info/rfc8655>.
[RFC8938] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane
Framework", RFC 8938, DOI 10.17487/RFC8938, November 2020,
<https://www.rfc-editor.org/info/rfc8938>.
[RFC8939] Varga, B., Ed., Farkas, J., Berger, L., Fedyk, D., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane:
IP", RFC 8939, DOI 10.17487/RFC8939, November 2020,
<https://www.rfc-editor.org/info/rfc8939>.
14.2. Informative References 14.2. Informative References
[ARINC664P7] [ARINC664P7]
ARINC, "ARINC 664 Aircraft Data Network, Part 7, Avionics ARINC, "ARINC 664 Aircraft Data Network, Part 7, Avionics
Full-Duplex Switched Ethernet Network", 2009. Full-Duplex Switched Ethernet Network", 2009.
[I-D.ietf-detnet-data-plane-framework]
Varga, B., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "DetNet Data Plane Framework", draft-ietf-detnet-
data-plane-framework-06 (work in progress), May 2020.
[I-D.ietf-detnet-flow-information-model] [I-D.ietf-detnet-flow-information-model]
Varga, B., Farkas, J., Cummings, R., Jiang, Y., and D. Varga, B., Farkas, J., Cummings, R., Jiang, Y., and D.
Fedyk, "DetNet Flow Information Model", draft-ietf-detnet- Fedyk, "DetNet Flow Information Model", draft-ietf-detnet-
flow-information-model-10 (work in progress), May 2020. flow-information-model-12 (work in progress), December
2020.
[I-D.ietf-detnet-ip-oam]
Mirsky, G., Chen, M., and D. Black, "Operations,
Administration and Maintenance (OAM) for Deterministic
Networks (DetNet) with IP Data Plane", draft-ietf-detnet-
ip-oam-00 (work in progress), September 2020.
[I-D.ietf-detnet-ip-over-mpls]
Varga, B., Berger, L., Fedyk, D., Bryant, S., and J.
Korhonen, "DetNet Data Plane: IP over MPLS", draft-ietf-
detnet-ip-over-mpls-09 (work in progress), October 2020.
[I-D.ietf-detnet-ip-over-tsn] [I-D.ietf-detnet-ip-over-tsn]
Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet
Data Plane: IP over IEEE 802.1 Time Sensitive Networking Data Plane: IP over IEEE 802.1 Time Sensitive Networking
(TSN)", draft-ietf-detnet-ip-over-tsn-03 (work in (TSN)", draft-ietf-detnet-ip-over-tsn-04 (work in
progress), June 2020. progress), November 2020.
[I-D.ietf-detnet-mpls-oam]
Mirsky, G. and M. Chen, "Operations, Administration and
Maintenance (OAM) for Deterministic Networks (DetNet) with
MPLS Data Plane", draft-ietf-detnet-mpls-oam-01 (work in
progress), July 2020.
[I-D.ietf-detnet-mpls-over-udp-ip]
Varga, B., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "DetNet Data Plane: MPLS over UDP/IP", draft-ietf-
detnet-mpls-over-udp-ip-07 (work in progress), October
2020.
[I-D.ietf-ipsecme-g-ikev2]
Smyslov, V. and B. Weis, "Group Key Management using
IKEv2", draft-ietf-ipsecme-g-ikev2-01 (work in progress),
July 2020.
[I-D.ietf-mpls-opportunistic-encrypt] [I-D.ietf-mpls-opportunistic-encrypt]
Farrel, A. and S. Farrell, "Opportunistic Security in MPLS Farrel, A. and S. Farrell, "Opportunistic Security in MPLS
Networks", draft-ietf-mpls-opportunistic-encrypt-03 (work Networks", draft-ietf-mpls-opportunistic-encrypt-03 (work
in progress), March 2017. in progress), March 2017.
[I-D.varga-detnet-service-model] [I-D.varga-detnet-service-model]
Varga, B. and J. Farkas, "DetNet Service Model", draft- Varga, B. and J. Farkas, "DetNet Service Model", draft-
varga-detnet-service-model-02 (work in progress), May varga-detnet-service-model-02 (work in progress), May
2017. 2017.
skipping to change at page 44, line 47 skipping to change at page 49, line 25
[IEEE1588] [IEEE1588]
IEEE, "IEEE 1588 Standard for a Precision Clock IEEE, "IEEE 1588 Standard for a Precision Clock
Synchronization Protocol for Networked Measurement and Synchronization Protocol for Networked Measurement and
Control Systems Version 2", 2008. Control Systems Version 2", 2008.
[IEEE802.1AE-2018] [IEEE802.1AE-2018]
IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC IEEE Standards Association, "IEEE Std 802.1AE-2018 MAC
Security (MACsec)", 2018, Security (MACsec)", 2018,
<https://ieeexplore.ieee.org/document/8585421>. <https://ieeexplore.ieee.org/document/8585421>.
[IEEE802.1BA]
IEEE Standards Association, "IEEE Standard for Local and
Metropolitan Area Networks -- Audio Video Bridging (AVB)
Systems", 2011,
<https://ieeexplore.ieee.org/document/6032690>.
[IEEE802.1Q]
IEEE Standards Association, "IEEE Standard for Local and
metropolitan area networks--Bridges and Bridged Networks -
Annex J - Connectivity Fault Management", 2014,
<https://ieeexplore.ieee.org/document/6991462>.
[IEEE802.1Qbv-2015] [IEEE802.1Qbv-2015]
IEEE Standards Association, "IEEE Standard for Local and IEEE Standards Association, "IEEE Standard for Local and
metropolitan area networks -- Bridges and Bridged Networks metropolitan area networks -- Bridges and Bridged Networks
- Amendment 25: Enhancements for Scheduled Traffic", 2015, - Amendment 25: Enhancements for Scheduled Traffic", 2015,
<https://ieeexplore.ieee.org/document/8613095>. <https://ieeexplore.ieee.org/document/8613095>.
[IEEE802.1Qch-2017] [IEEE802.1Qch-2017]
IEEE Standards Association, "IEEE Standard for Local and IEEE Standards Association, "IEEE Standard for Local and
metropolitan area networks--Bridges and Bridged Networks-- metropolitan area networks--Bridges and Bridged Networks--
Amendment 29: Cyclic Queuing and Forwarding", 2017, Amendment 29: Cyclic Queuing and Forwarding", 2017,
<https://ieeexplore.ieee.org/document/7961303>. <https://ieeexplore.ieee.org/document/7961303>.
[IETF_YANG_SEC]
IETF, "YANG Module Security Considerations", 2018,
<https://trac.ietf.org/trac/ops/wiki/yang-security-
guidelines>.
[IT_DEF] Wikipedia, "IT Definition", 2020, [IT_DEF] Wikipedia, "IT Definition", 2020,
<https://en.wikiquote.org/wiki/Information_technology>. <https://en.wikiquote.org/wiki/Information_technology>.
[OT_DEF] Wikipedia, "OT Definition", 2020, [OT_DEF] Wikipedia, "OT Definition", 2020,
<https://en.wikipedia.org/wiki/Operational_technology>. <https://en.wikipedia.org/wiki/Operational_technology>.
[RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black, [RFC2474] Nichols, K., Blake, S., Baker, F., and D. Black,
"Definition of the Differentiated Services Field (DS "Definition of the Differentiated Services Field (DS
Field) in the IPv4 and IPv6 Headers", RFC 2474, Field) in the IPv4 and IPv6 Headers", RFC 2474,
DOI 10.17487/RFC2474, December 1998, DOI 10.17487/RFC2474, December 1998,
skipping to change at page 45, line 47 skipping to change at page 50, line 41
[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation [RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985, Edge-to-Edge (PWE3) Architecture", RFC 3985,
DOI 10.17487/RFC3985, March 2005, DOI 10.17487/RFC3985, March 2005,
<https://www.rfc-editor.org/info/rfc3985>. <https://www.rfc-editor.org/info/rfc3985>.
[RFC4301] Kent, S. and K. Seo, "Security Architecture for the [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, DOI 10.17487/RFC4301, Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
December 2005, <https://www.rfc-editor.org/info/rfc4301>. December 2005, <https://www.rfc-editor.org/info/rfc4301>.
[RFC4447] Martini, L., Ed., Rosen, E., El-Aawar, N., Smith, T., and [RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
G. Heron, "Pseudowire Setup and Maintenance Using the (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
Label Distribution Protocol (LDP)", RFC 4447, <https://www.rfc-editor.org/info/rfc5880>.
DOI 10.17487/RFC4447, April 2006,
<https://www.rfc-editor.org/info/rfc4447>.
[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
"Network Time Protocol Version 4: Protocol and Algorithms "Network Time Protocol Version 4: Protocol and Algorithms
Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
<https://www.rfc-editor.org/info/rfc5905>. <https://www.rfc-editor.org/info/rfc5905>.
[RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS [RFC5920] Fang, L., Ed., "Security Framework for MPLS and GMPLS
Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010, Networks", RFC 5920, DOI 10.17487/RFC5920, July 2010,
<https://www.rfc-editor.org/info/rfc5920>. <https://www.rfc-editor.org/info/rfc5920>.
[RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau, [RFC5921] Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau,
L., and L. Berger, "A Framework for MPLS in Transport L., and L. Berger, "A Framework for MPLS in Transport
Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010, Networks", RFC 5921, DOI 10.17487/RFC5921, July 2010,
<https://www.rfc-editor.org/info/rfc5921>. <https://www.rfc-editor.org/info/rfc5921>.
[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>.
[RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M. [RFC6073] Martini, L., Metz, C., Nadeau, T., Bocci, M., and M.
Aissaoui, "Segmented Pseudowire", RFC 6073, Aissaoui, "Segmented Pseudowire", RFC 6073,
DOI 10.17487/RFC6073, January 2011, DOI 10.17487/RFC6073, January 2011,
<https://www.rfc-editor.org/info/rfc6073>. <https://www.rfc-editor.org/info/rfc6073>.
[RFC6274] Gont, F., "Security Assessment of the Internet Protocol
Version 4", RFC 6274, DOI 10.17487/RFC6274, July 2011,
<https://www.rfc-editor.org/info/rfc6274>.
[RFC6478] Martini, L., Swallow, G., Heron, G., and M. Bocci, [RFC6478] Martini, L., Swallow, G., Heron, G., and M. Bocci,
"Pseudowire Status for Static Pseudowires", RFC 6478, "Pseudowire Status for Static Pseudowires", RFC 6478,
DOI 10.17487/RFC6478, May 2012, DOI 10.17487/RFC6478, May 2012,
<https://www.rfc-editor.org/info/rfc6478>. <https://www.rfc-editor.org/info/rfc6478>.
[RFC6632] Ersue, M., Ed. and B. Claise, "An Overview of the IETF
Network Management Standards", RFC 6632,
DOI 10.17487/RFC6632, June 2012,
<https://www.rfc-editor.org/info/rfc6632>.
[RFC6941] Fang, L., Ed., Niven-Jenkins, B., Ed., Mansfield, S., Ed., [RFC6941] Fang, L., Ed., Niven-Jenkins, B., Ed., Mansfield, S., Ed.,
and R. Graveman, Ed., "MPLS Transport Profile (MPLS-TP) and R. Graveman, Ed., "MPLS Transport Profile (MPLS-TP)
Security Framework", RFC 6941, DOI 10.17487/RFC6941, April Security Framework", RFC 6941, DOI 10.17487/RFC6941, April
2013, <https://www.rfc-editor.org/info/rfc6941>. 2013, <https://www.rfc-editor.org/info/rfc6941>.
[RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in
Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384, Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384,
October 2014, <https://www.rfc-editor.org/info/rfc7384>. October 2014, <https://www.rfc-editor.org/info/rfc7384>.
[RFC7567] Baker, F., Ed. and G. Fairhurst, Ed., "IETF
Recommendations Regarding Active Queue Management",
BCP 197, RFC 7567, DOI 10.17487/RFC7567, July 2015,
<https://www.rfc-editor.org/info/rfc7567>.
[RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID [RFC7835] Saucez, D., Iannone, L., and O. Bonaventure, "Locator/ID
Separation Protocol (LISP) Threat Analysis", RFC 7835, Separation Protocol (LISP) Threat Analysis", RFC 7835,
DOI 10.17487/RFC7835, April 2016, DOI 10.17487/RFC7835, April 2016,
<https://www.rfc-editor.org/info/rfc7835>. <https://www.rfc-editor.org/info/rfc7835>.
[RFC8077] Martini, L., Ed. and G. Heron, Ed., "Pseudowire Setup and
Maintenance Using the Label Distribution Protocol (LDP)",
STD 84, RFC 8077, DOI 10.17487/RFC8077, February 2017,
<https://www.rfc-editor.org/info/rfc8077>.
[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>.
[RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases", [RFC8578] Grossman, E., Ed., "Deterministic Networking Use Cases",
RFC 8578, DOI 10.17487/RFC8578, May 2019, RFC 8578, DOI 10.17487/RFC8578, May 2019,
<https://www.rfc-editor.org/info/rfc8578>. <https://www.rfc-editor.org/info/rfc8578>.
[RS_DEF] Wikipedia, "RS Definition", 2020, [RS_DEF] Wikipedia, "RS Definition", 2020,
<https://en.wikipedia.org/wiki/Network_segmentation>. <https://en.wikipedia.org/wiki/Network_segmentation>.
Authors' Addresses Authors' Addresses
Ethan Grossman (editor) Ethan Grossman (editor)
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