--- 1/draft-ietf-detnet-security-08.txt 2020-03-18 19:13:14.321577933 -0700 +++ 2/draft-ietf-detnet-security-09.txt 2020-03-18 19:13:14.405580067 -0700 @@ -1,176 +1,192 @@ Internet Engineering Task Force T. Mizrahi Internet-Draft HUAWEI Intended status: Informational E. Grossman, Ed. -Expires: August 6, 2020 DOLBY - A. Hacker - MISTIQ - S. Das - Applied Communication Sciences - J. Dowdell - Airbus Defence and Space - H. Austad - SINTEF Digital - N. Finn - HUAWEI - February 3, 2020 +Expires: September 19, 2020 DOLBY + March 18, 2020 Deterministic Networking (DetNet) Security Considerations - draft-ietf-detnet-security-08 + draft-ietf-detnet-security-09 Abstract - A deterministic network is one that can carry data flows for real- - time applications with extremely low data loss rates and bounded - latency. Deterministic networks have been successfully deployed in - real-time operational technology (OT) applications for some years. - However, such networks are typically isolated from external access, - and thus the security threat from external attackers is low. IETF - Deterministic Networking (DetNet) specifies a set of technologies - that enable creation of deterministic networks on IP-based networks - of potentially wide area (on 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 on a wide area IP-based network, and thus can - present security considerations that may be new to IP-based wide area - network designers. This document, intended for use by DetNet network - designers, provides insight into these security considerations. + A DetNet (deterministic network) provides specific performance + guarantees to its data flows, such as extremely low data loss rates + and bounded latency. As a result, securing a DetNet implies that in + addition to the best practice security measures taken for any + mission-critical network, additional security measures may be needed + whose purpose is exclusively to secure the intended operation of + these novel service properties. This document addresses specifically + those security considerations, with the assumption that the reader is + already familiar with network security best practices for the data + plane technologies underlying a given DetNet implementation. This + document defines a threat model and a taxonomy of relevant attacks, + including their potential impacts and mitigations. + + A given DetNet may require securing only certain aspects of DetNet + performance, for example extremely low data loss rates but not + necessarily bounded latency. Therefore this document provides an + association of threats against various use cases by industry, and + also against the individual service properties as defined in the + DetNet Use Cases. + + This document also addresses common DetNet security considerations + related to the IP and MPLS data plane technologies (the first to be + identified as supported by DetNet), thereby complementing the + Security Considerations sections of the various DetNet Data Plane + (and other) DetNet documents. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on August 6, 2020. + This Internet-Draft will expire on September 19, 2020. Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4 - 2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 5 + 2. Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Security Threats . . . . . . . . . . . . . . . . . . . . . . 6 3.1. Threat Model . . . . . . . . . . . . . . . . . . . . . . 6 3.2. Threat Analysis . . . . . . . . . . . . . . . . . . . . . 7 3.2.1. Delay . . . . . . . . . . . . . . . . . . . . . . . . 7 3.2.1.1. Delay Attack . . . . . . . . . . . . . . . . . . 7 3.2.2. DetNet Flow Modification or Spoofing . . . . . . . . 7 3.2.3. Resource Segmentation or Slicing . . . . . . . . . . 7 - 3.2.3.1. Inter-segment Attack . . . . . . . . . . . . . . 7 + 3.2.3.1. Inter-segment Attack . . . . . . . . . . . . . . 8 3.2.4. Packet Replication and Elimination . . . . . . . . . 8 3.2.4.1. Replication: Increased Attack Surface . . . . . . 8 3.2.4.2. Replication-related Header Manipulation . . . . . 8 - 3.2.5. Path Choice . . . . . . . . . . . . . . . . . . . . . 8 - 3.2.5.1. Path Manipulation . . . . . . . . . . . . . . . . 8 + 3.2.5. Path Choice . . . . . . . . . . . . . . . . . . . . . 9 + 3.2.5.1. Path Manipulation . . . . . . . . . . . . . . . . 9 3.2.5.2. Path Choice: Increased Attack Surface . . . . . . 9 - 3.2.6. Control Plane . . . . . . . . . . . . . . . . . . . . 9 + 3.2.6. Controller Plane . . . . . . . . . . . . . . . . . . 9 3.2.6.1. Control or Signaling Packet Modification . . . . 9 3.2.6.2. Control or Signaling Packet Injection . . . . . . 9 3.2.7. Scheduling or Shaping . . . . . . . . . . . . . . . . 9 3.2.7.1. Reconnaissance . . . . . . . . . . . . . . . . . 9 - 3.2.8. Time Synchronization Mechanisms . . . . . . . . . . . 9 - 3.3. Threat Summary . . . . . . . . . . . . . . . . . . . . . 9 + 3.3. Threat Summary . . . . . . . . . . . . . . . . . . . . . 10 4. Security Threat Impacts . . . . . . . . . . . . . . . . . . . 10 4.1. Delay-Attacks . . . . . . . . . . . . . . . . . . . . . . 13 4.1.1. Data Plane Delay Attacks . . . . . . . . . . . . . . 13 - 4.1.2. Control Plane Delay Attacks . . . . . . . . . . . . . 14 + 4.1.2. Controller Plane Delay Attacks . . . . . . . . . . . 14 4.2. Flow Modification and Spoofing . . . . . . . . . . . . . 14 4.2.1. Flow Modification . . . . . . . . . . . . . . . . . . 14 4.2.2. Spoofing . . . . . . . . . . . . . . . . . . . . . . 14 4.2.2.1. Dataplane Spoofing . . . . . . . . . . . . . . . 14 - 4.2.2.2. Control Plane Spoofing . . . . . . . . . . . . . 15 + 4.2.2.2. Controller Plane Spoofing . . . . . . . . . . . . 15 4.3. Segmentation attacks (injection) . . . . . . . . . . . . 15 4.3.1. Data Plane Segmentation . . . . . . . . . . . . . . . 15 - 4.3.2. Control Plane segmentation . . . . . . . . . . . . . 15 + 4.3.2. Controller Plane Segmentation . . . . . . . . . . . . 15 4.4. Replication and Elimination . . . . . . . . . . . . . . . 16 4.4.1. Increased Attack Surface . . . . . . . . . . . . . . 16 - 4.4.2. Header Manipulation at Elimination Bridges . . . . . 16 + 4.4.2. Header Manipulation at Elimination Routers . . . . . 16 4.5. Control or Signaling Packet Modification . . . . . . . . 16 4.6. Control or Signaling Packet Injection . . . . . . . . . . 16 4.7. Reconnaissance . . . . . . . . . . . . . . . . . . . . . 16 4.8. Attacks on Time Sync Mechanisms . . . . . . . . . . . . . 17 4.9. Attacks on Path Choice . . . . . . . . . . . . . . . . . 17 5. Security Threat Mitigation . . . . . . . . . . . . . . . . . 17 5.1. Path Redundancy . . . . . . . . . . . . . . . . . . . . . 17 5.2. Integrity Protection . . . . . . . . . . . . . . . . . . 17 5.3. DetNet Node Authentication . . . . . . . . . . . . . . . 18 - 5.4. Dummy Traffic Insertion . . . . . . . . . . . . . . . . . 18 + 5.4. Dummy Traffic Insertion . . . . . . . . . . . . . . . . . 19 5.5. Encryption . . . . . . . . . . . . . . . . . . . . . . . 19 5.5.1. Encryption Considerations for DetNet . . . . . . . . 19 5.6. Control and Signaling Message Protection . . . . . . . . 20 5.7. Dynamic Performance Analytics . . . . . . . . . . . . . . 21 5.8. Mitigation Summary . . . . . . . . . . . . . . . . . . . 21 6. Association of Attacks to Use Cases . . . . . . . . . . . . . 23 6.1. Use Cases by Common Themes . . . . . . . . . . . . . . . 23 - 6.1.1. Network Layer - AVB/TSN Ethernet . . . . . . . . . . 23 + 6.1.1. Sub-Network Layer . . . . . . . . . . . . . . . . . . 23 6.1.2. Central Administration . . . . . . . . . . . . . . . 24 6.1.3. Hot Swap . . . . . . . . . . . . . . . . . . . . . . 24 6.1.4. Data Flow Information Models . . . . . . . . . . . . 25 6.1.5. L2 and L3 Integration . . . . . . . . . . . . . . . . 25 6.1.6. End-to-End Delivery . . . . . . . . . . . . . . . . . 25 - 6.1.7. Proprietary Deterministic Ethernet Networks . . . . . 25 + 6.1.7. Proprietary Deterministic Ethernet Networks . . . . . 26 6.1.8. Replacement for Proprietary Fieldbuses . . . . . . . 26 6.1.9. Deterministic vs Best-Effort Traffic . . . . . . . . 26 6.1.10. Deterministic Flows . . . . . . . . . . . . . . . . . 27 6.1.11. Unused Reserved Bandwidth . . . . . . . . . . . . . . 27 6.1.12. Interoperability . . . . . . . . . . . . . . . . . . 27 - 6.1.13. Cost Reductions . . . . . . . . . . . . . . . . . . . 27 + 6.1.13. Cost Reductions . . . . . . . . . . . . . . . . . . . 28 6.1.14. Insufficiently Secure Devices . . . . . . . . . . . . 28 6.1.15. DetNet Network Size . . . . . . . . . . . . . . . . . 28 - 6.1.16. Multiple Hops . . . . . . . . . . . . . . . . . . . . 28 + 6.1.16. Multiple Hops . . . . . . . . . . . . . . . . . . . . 29 6.1.17. Level of Service . . . . . . . . . . . . . . . . . . 29 6.1.18. Bounded Latency . . . . . . . . . . . . . . . . . . . 29 6.1.19. Low Latency . . . . . . . . . . . . . . . . . . . . . 30 6.1.20. Bounded Jitter (Latency Variation) . . . . . . . . . 30 6.1.21. Symmetrical Path Delays . . . . . . . . . . . . . . . 30 - 6.1.22. Reliability and Availability . . . . . . . . . . . . 30 + 6.1.22. Reliability and Availability . . . . . . . . . . . . 31 6.1.23. Redundant Paths . . . . . . . . . . . . . . . . . . . 31 6.1.24. Security Measures . . . . . . . . . . . . . . . . . . 31 6.2. Attack Types by Use Case Common Theme . . . . . . . . . . 31 6.3. Security Considerations for OAM Traffic . . . . . . . . . 34 7. DetNet Technology-Specific Threats . . . . . . . . . . . . . 34 7.1. IP . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 7.2. MPLS . . . . . . . . . . . . . . . . . . . . . . . . . . 36 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 37 9. Security Considerations . . . . . . . . . . . . . . . . . . . 37 - 10. Informative References . . . . . . . . . . . . . . . . . . . 37 - Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 39 + 10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 37 + 11. Informative References . . . . . . . . . . . . . . . . . . . 37 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 40 1. Introduction + A deterministic network is one that can carry data flows for real- + time applications with extremely low data loss rates and bounded + latency. Deterministic networks have been successfully deployed in + real-time operational technology (OT) applications for some years. + However, such networks are typically isolated from external access, + and thus the security threat from external attackers is low. IETF + Deterministic Networking (DetNet) specifies a set of technologies + that enable creation of deterministic networks on IP-based networks + of potentially wide area (on 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 on a wide area IP-based network, and thus can + present security considerations that may be new to IP-based wide area + network designers. This document, intended for use by DetNet network + designers, provides insight into these security considerations. + Security is of particularly high importance in DetNet networks because many of the use cases which are enabled by DetNet [RFC8578] include control of physical devices (power grid components, industrial controls, building controls) which can have high operational costs for failure, and present potentially attractive targets for cyber-attackers. 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 both IT traffic and OT traffic, thus exposing potentially sensitive @@ -178,96 +194,87 @@ because they were under a separate control system or otherwise isolated from the IT network, for example [ARINC664P7]). Security 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 Internet; this document focuses on the issues that are specific to the DetNet technologies and use cases. Given the above considerations, securing a DetNet starts with a scrupulously well-designed and well-managed engineered network following industry best practices for security at both the data plane - and control plane; this is the assumed starting point for the + and controller plane; this is the assumed starting point for the considerations discussed herein. In this context we view the network design and managment aspects of network security as being primarily concerned with denial-of service prevention by ensuring that DetNet traffic goes where it's supposed to and that an external attacker can't inject traffic that disrupts the DetNet's delivery timing assurance. The time-specific aspects of DetNet security presented here take up where the design and management aspects leave off. - The security requirements for any given DetNet network are + The exact security requirements for any given DetNet network 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 [I-D.ietf-detnet-ip]). + use, for example [I-D.ietf-detnet-ip]). A general introduction to + the DetNet architecture can be found in [RFC8655] and it is also + recommended to be familiar with the Data Plane model + [I-D.ietf-detnet-data-plane-framework] and Flow Information Model + [I-D.ietf-detnet-flow-information-model]. The DetNet technologies include ways to: - o Reserve data plane resources for DetNet flows in some or all of - the intermediate nodes (e.g. bridges or routers) along the path of - the flow + o Assign data plane resources for DetNet flows in some or all of the + intermediate nodes (routers) along the path of the flow o Provide explicit routes for DetNet flows that do not rapidly change with the network topology 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 path This document includes sections on threat modeling and analysis, threat impact and mitigation, and the association of attacks with use cases based on the Use Case Common Themes section of the DetNet Use - Cases [RFC8578]. + Cases. 2. Abbreviations IT Information technology (the application of computers to store, study, retrieve, transmit, and manipulate data or information, often in the context of a business or other enterprise - Wikipedia). OT Operational Technology (the hardware and software dedicated to detecting or causing changes in physical processes through direct monitoring and/or control of physical devices such as valves, pumps, etc. - Wikipedia) MITM Man in the Middle - SN Sequence Number - - STRIDE Addresses risk and severity associated with threat - categories: Spoofing identity, Tampering with data, Repudiation, - Information disclosure, Denial of service, Elevation of privilege. - - DREAD Compares and prioritizes risk represented by these threat - categories: Damage potential, Reproducibility, Exploitability, how - many Affected users, Discoverability. - - PTP Precision Time Protocol [IEEE1588] - 3. Security Threats This section presents a threat model, and analyzes the possible threats in a DetNet-enabled network. The threats considered in this section are independent of any specific technologies used to implement the DetNet; Section 7) considers attacks that are associated with the DetNet technologies encompassed by [I-D.ietf-detnet-data-plane-framework]. - We distinguish control 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 the motivation behind them, are different. For example, a delay - attack is more relevant to data plane than to control plane. 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 the - control plane. + attack is more relevant to data plane than to controller plane. + 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 + the controller plane. 3.1. Threat Model The threat model used in this memo is based on the threat model of Section 3.1 of [RFC7384]. This model classifies attackers based on two criteria: o Internal vs. external: internal attackers either have access to a trusted segment of the network or possess the encryption or authentication keys. External attackers, on the other hand, do @@ -276,23 +283,23 @@ o Man in the Middle (MITM) vs. packet injector: MITM attackers are located in a position that allows interception and modification of in-flight protocol packets, whereas a traffic injector can only attack by generating protocol packets. Care has also been taken to adhere to Section 5 of [RFC3552], both with respect to which attacks are considered out-of-scope for this document, but also which are considered to be the most common threats (explored further in Section 3.2. Most of the direct threats to - DetNet are Active attacks, but it is highly suggested that DetNet + DetNet are active attacks, but it is highly suggested that DetNet application developers take appropriate measures to protect the - content of the streams from passive attacks. + content of the DetNet flows from passive attacks. DetNet-Service, one of the service scenarios described in [I-D.varga-detnet-service-model], is the case where a service connects DetNet networking islands, i.e. two or more otherwise independent DetNet network domains are connected via a link that is not intrinsically part of either network. This implies that there could be DetNet traffic flowing over a non-DetNet link, which may provide an attacker with an advantageous opportunity to tamper with DetNet traffic. The security properties of non-DetNet links are outside of the scope of DetNet Security, but it should be noted that @@ -315,28 +322,27 @@ An attacker can modify some header fields of en route packets in a way that causes the DetNet flow identification mechanisms to misclassify the flow. Alternatively, the attacker can inject traffic that is tailored to appear as if it belongs to a legitimate DetNet flow. The potential consequence is that the DetNet flow resource allocation cannot guarantee the performance that is expected when the flow identification works correctly. 3.2.3. Resource Segmentation or Slicing - 3.2.3.1. Inter-segment Attack - An attacker can inject traffic, consuming network device resources, - thereby affecting DetNet flows. This can be performed using non- - DetNet traffic that affects DetNet traffic, or by using DetNet - traffic from one DetNet flow that affects traffic from different - DetNet flows. + An attacker can inject traffic that will consume network resources + such that it affects DetNet flows. This can be performed using non- + DetNet traffic that indirectly affects DetNet traffic (hardware + resource exhaustion), or by using DetNet traffic from one DetNet flow + that directly affects traffic from different DetNet flows. 3.2.4. Packet Replication and Elimination 3.2.4.1. Replication: Increased Attack Surface Redundancy is intended to increase the robustness and survivability of DetNet flows, and replication over multiple paths can potentially mitigate an attack that is limited to a single path. However, the fact that packets are replicated over multiple paths increases the attack surface of the network, i.e., there are more points in the @@ -357,40 +363,42 @@ access to a single path can cause packets from other paths to be dropped, thus compromising some of the advantage of path redundancy. o Flow hijacking - an attacker can hijack a DetNet flow with access to a single path by systematically replacing the SNs on the given path with higher SN values. For example, an attacker can replace every SN value S with a higher value S+C, where C is a constant integer. Thus, the attacker creates a false illusion that the attacked path has the lowest delay, causing all packets from other - paths to be eliminated. Once the flow is hijacked the attacker - can either replace en route packets with malicious packets, or + paths to be eliminated in favor of the attacked path. Once the + flow from the compromised path is favored by the elminating + bridge, the flow is hijacked by the attacker. It is now posible + to either replace en route packets with malicious packets, or simply injecting errors, causing the packets to be dropped at their destination. 3.2.5. Path Choice 3.2.5.1. Path Manipulation An attacker can maliciously change, add, or remove a path, thereby affecting the corresponding DetNet flows that use the path. 3.2.5.2. Path Choice: Increased Attack Surface One of the possible consequences of a path manipulation attack is an increased attack surface. Thus, when the attack described in the previous subsection is implemented, it may increase the potential of other attacks to be performed. -3.2.6. Control Plane +3.2.6. Controller Plane 3.2.6.1. Control or Signaling Packet Modification An attacker can maliciously modify en route control packets in order to disrupt or manipulate the DetNet path/resource allocation. 3.2.6.2. Control or Signaling Packet Injection An attacker can maliciously inject control packets in order to disrupt or manipulate the DetNet path/resource allocation. @@ -593,145 +601,149 @@ 4.1. Delay-Attacks 4.1.1. Data Plane Delay Attacks Note that 'delay attack' also includes the possibility of a 'negative delay' or early arrival of a packet, or possibly adversely changing the timestamp value. Delayed messages in a DetNet link can result in the same behavior as dropped messages in ordinary networks as the services attached to the - stream has strict deterministic requirements. + DetNet flow have strict deterministic requirements. For a single path scenario, disruption is a real possibility, whereas - in a multipath scenario, large delays or instabilities in one stream - can lead to increased buffer and CPU resources on the elimination - bridge. + in a multipath scenario, large delays or instabilities in one DetNet + flow can lead to increased buffer and processor resources at the + eliminating router. A data-plane delay attack on a system controlling substantial moving devices, for example in industrial automation, can cause physical damage. For example, if the network promises a bounded latency of 2ms for a flow, yet the machine receives it with 5ms latency, the machine's control loop can become unstable. -4.1.2. Control Plane Delay Attacks +4.1.2. Controller Plane Delay Attacks In and of itself, this is not directly a threat to the DetNet service, but the effects of delaying control messages can have quite adverse effects later. o Delayed tear-down can lead to resource leakage, which in turn can - result in failure to allocate new streams finally giving rise to a - denial of service attack. + result in failure to allocate new DetNet flows, finally giving + rise to a denial of service attack. - o Failure to deliver, or severely delaying, signalling messages - adding an end-point to a multicast-group will prevent the new EP - from receiving expected frames thus disrupting expected behavior. + o Failure to deliver, or severely delaying, controller plane + messages adding an endpoint to a multicast-group will prevent the + new endpoint from receiving expected frames thus disrupting + expected behavior. - o Delaying messages removing an EP from a group can lead to loss of - privacy as the EP will continue to receive messages even after it - is supposedly removed. + o Delaying messages removing an endpoint from a group can lead to + loss of privacy as the endpoint will continue to receive messages + even after it is supposedly removed. 4.2. Flow Modification and Spoofing 4.2.1. Flow Modification If the contents of a packet header or body can be modified by the attacker, this can cause the packet to be routed incorrectly or dropped, or the payload to be corrupted or subtly modified. 4.2.2. Spoofing 4.2.2.1. Dataplane Spoofing Spoofing dataplane messages can result in increased resource - consumptions on the bridges throughout the network as it will - increase buffer usage and CPU utilization. This can lead to resource - exhaustion and/or increased delay. + consumptions on the routers throughout the network as it will + increase buffer usage and processor utilization. This can lead to + resource exhaustion and/or increased delay. If the attacker manages to create valid headers, the false messages can be forwarded through the network, using part of the allocated bandwidth. This in turn can cause legitimate messages to be dropped - when the budget has been exhausted. + when the resource budget has been exhausted. Finally, the endpoint will have to deal with invalid messages being delivered to the endpoint instead of (or in addition to) a valid message. -4.2.2.2. Control Plane Spoofing +4.2.2.2. Controller Plane Spoofing - A successful control plane spoofing-attack will potentionally have + A successful controller plane spoofing-attack will potentionally have adverse effects. It can do virtually anything from: - o modifying existing streams by changing the available bandwidth + o modifying existing DetNet flows by changing the available + bandwidth - o add or remove endpoints from a stream + o add or remove endpoints from a DetNet flow - o drop streams completly + o drop DetNet flows completely - o falsely create new streams (exhaust the systems resources, or to - enable streams outside the Network engineer's control) + o falsely create new DetNet flows (exhaust the systems resources, or + to enable DetNet flows that are outside the Network Engineer's + control) 4.3. Segmentation attacks (injection) 4.3.1. Data Plane Segmentation - Injection of false messages in a DetNet stream could lead to - exhaustion of the available bandwidth for a stream if the bridges - accounts false messages to the stream's budget. - - In a multipath scenario, injected messages will cause increased CPU - utilization in elimination bridges. If enough paths are subject to - malicious injection, the legitimate messages can be dropped. - Likewise it can cause an increase in buffer usage. In total, it will - consume more resources in the bridges than normal, giving rise to a - resource exhaustion attack on the bridges. + Injection of false messages in a DetNet flow could lead to exhaustion + of the available bandwidth for that flow if the routers attribute + these false messages to that flow's budget. - If a stream is interrupted, the end application will be affected by - what is now a non-deterministic stream. + In a multipath scenario, injected messages will cause increased + processor utilization in elimination routers. If enough paths are + subject to malicious injection, the legitimate messages can be + dropped. Likewise it can cause an increase in buffer usage. In + total, it will consume more resources in the routers than normal, + giving rise to a resource exhaustion attack on the routers. -4.3.2. Control Plane segmentation + If a DetNet flow is interrupted, the end application will be affected + by what is now a non-deterministic flow. - A successful Control Plane segmentation attack control messages to be - interpreted by nodes in the network, unbeknownst to the central - controller or the network engineer. This has the potential to create +4.3.2. Controller Plane Segmentation - o new streams (exhausting resources) + In a successful controller plane segmentation attack, control + messages are acted on by nodes in the network, unbeknownst to the + central controller or the network engineer. This has the potential + to: - o drop existing (denial of service) + o create new DetNet flows (exhausting resources) + o drop existing DetNet flows (denial of service) o add/remove end-stations to a multicast group (loss of privacy) - o modify the stream attributes (affecting available bandwidth + o modify the DetNet flow attributes (affecting available bandwidth 4.4. Replication and Elimination The Replication and Elimination is relevant only to Data Plane - messages as Signalling is not subject to multipath routing. + messages as controller plane messages are not subject to multipath + routing. 4.4.1. Increased Attack Surface Covered briefly in Section 4.3 -4.4.2. Header Manipulation at Elimination Bridges +4.4.2. Header Manipulation at Elimination Routers Covered briefly in Section 4.3 4.5. Control or Signaling Packet Modification - If the control plane packets are subject to manipulation undetected, - the network can be severely compromised. + If control packets are subject to manipulation undetected, the + network can be severely compromised. 4.6. Control or Signaling Packet Injection - If an attacker can inject control plane packets undetected, the - network can be severely compromised. + If an attacker can inject control packets undetected, the network can + be severely compromised. 4.7. Reconnaissance Of all the attacks, this is one of the most difficult to detect and counter. Often, an attacker will start out by observing the traffic going through the network and use the knowledge gathered in this phase to mount future attacks. The attacker can, at their leisure, observe over time all aspects of the messaging and signalling, learning the intent and purpose of all @@ -784,25 +796,24 @@ locate the source of a MITM attacker. A delay modulation attack could result in extensively exercising parts of the code that wouldn't normally be extensively exercised and thus might expose flaws in the system that might otherwise not be exposed. 5.2. Integrity Protection Description - An integrity protection mechanism, such as a Hash-based Message Authentication Code (HMAC) can be used to mitigate modification - attacks on IP packets. Integrity protection in the control plane - is discussed in Section 5.6. + attacks on IP packets. Integrity protection in the controller + plane is discussed in Section 5.6. Packet Sequence Number Integrity Considerations The use of PREOF in a DetNet implementation implies the use of a sequence number for each packet. There is a trust relationship between the device that adds the sequence number and the device that removes the sequence number. The sequence number may be end- to-end source to destination, or may be added/deleted by network edge devices. The adder and remover(s) have the trust relationship because they are the ones that ensure that the @@ -858,20 +870,23 @@ DetNet flows can in principle be forwarded in encrypted form at the DetNet layer, however, regarding encryption of IP headers see Section 7. Alternatively, if the payload is end-to-end encrypted at the application layer, the DetNet nodes should not have any need to inspect the payload itself, and thus the DetNet implementation can be data-agnostic. + Encryption can also be applied at the subnet layer, for example + for Ethernet using MACSec, as noted in Section 7. + Related attacks Encryption can be used to mitigate recon attacks (Section 3.2.7). However, for a DetNet network to give differentiated quality of service on a flow-by-flow basis, the network must be able to identify the flows individually. This implies that in a recon attack the attacker may also be able to track individual flows to learn more about the system. 5.5.1. Encryption Considerations for DetNet @@ -921,42 +936,41 @@ the latency calculations. 5.6. Control and Signaling Message Protection Description Control and sigaling messages can be protected using authentication and integrity protection mechanisms. Related attacks - These mechanisms can be used to mitigate various attacks on the - control plane, as described in Section 3.2.6, Section 3.2.8 and + controller plane, as described in Section 3.2.6, Section 3.2.8 and Section 3.2.5. 5.7. Dynamic Performance Analytics Description The expectation is that the network will have a way to monitor to detect if timing guarantees are not being met, and a way to alert - the control plane in that event. Information about the network + the controller plane in that event. Information about the network performance can be gathered in real-time in order to detect anomalies and unusual behavior that may be the symptom of a security attack. The gathered information can be based, for example, on per-flow counters, bandwidth measurement, and monitoring of packet arrival times. Unusual behavior or potentially malicious nodes can be reported to a management 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 - NETCONF. + YANG. Related attacks Performance analytics can be used to mitigate various attacks, including the ones described in Section 3.2.1 (Delay Attack), Section 3.2.3 (Resource Segmentation Attack), and Section 3.2.8 (Time Sync Attack). For example, in the case of data plane delay attacks, one possible mitigation is to timestamp the data at the source, and timestamp @@ -967,25 +981,20 @@ timestamps, although they may be used by the underlying transport (for example TSN) to provide the service. 5.8. Mitigation Summary The following table maps the attacks of Section 3 to the impacts of Section 4, and to the mitigations of the current section. Each row specifies an attack, the impact of this attack if it is successfully implemented, and possible mitigation methods. - Editor's note: Is this tabular summary of the above information - useful or necessary in this draft? If we opt to maintain the tables - then the WG needs to validate them for completeness and correctness - after all other draft comments have been addressed. - +----------------------+---------------------+---------------------+ | Attack | Impact | Mitigations | +----------------------+---------------------+---------------------+ |Delay Attack |-Non-deterministic |-Path redundancy | | | delay |-Performance | | |-Data disruption | analytics | | |-Increased resource | | | | consumption | | +----------------------+---------------------+---------------------+ |Reconnaissance |-Enabler for other |-Encryption | @@ -1049,53 +1058,54 @@ by industry. 6.1. Use Cases by Common Themes In this section we review each theme and discuss the attacks that are applicable to that theme, as well as anything specific about the impact and mitigations for that attack with respect to that theme. The table Figure 5 then provides a summary of the attacks that are applicable to each theme. -6.1.1. Network Layer - AVB/TSN Ethernet +6.1.1. Sub-Network Layer DetNet is expected to run over various transmission mediums, with - Ethernet being explicitly supported. Attacks such as Delay or + Ethernet being the first identified. Attacks such as Delay or Reconnaissance might be implemented differently on a different transmission medium, however the impact on the DetNet as a whole would be essentially the same. We thus conclude that all attacks and impacts that would be applicable to DetNet over Ethernet (i.e. all those named in this document) would also be applicable to DetNet over other transmission mediums. With respect to mitigations, some methods are specific to the Ethernet medium, for example time-aware scheduling using 802.1Qbv can protect against excessive use of bandwidth at the ingress - for other mediums, other mitigations would have to be implemented to provide analogous protection. 6.1.2. Central Administration - A DetNet network is expected to be controlled by a centralized - network configuration and control system (CNC). Such a system may be - in a single central location, or it may be distributed across - multiple control entities that function together as a unified control - system for the network. + A DetNet network can be controlled by a centralized network + configuration and control system. Such a system may be in a single + central location, or it may be distributed across multiple control + entities that function together as a unified control system for the + network. - In this document we distinguish between attacks on the DetNet Control - plane vs. Data plane. But is an attack affecting control plane - packets synonymous with an attack on the CNC itself? For purposes of - this document let us consider an attack on the CNC itself to be out - of scope, and consider all attacks named in this document which are - relevant to control plane packets to be relevant to this theme, - including Path Manipulation, Path Choice, Control Packet Modification - or Injection, Reconaissance and Attacks on Time Sync Mechanisms. + In this document we distinguish between attacks on the DetNet + Controller plane vs. Data plane. But is an attack affecting control + plane packets synonymous with an attack on the control plane itself? + For purposes of this document let us consider an attack on the + control system itself to be out of scope, and consider all attacks + named in this document which are relevant to controller plane packets + to be relevant to this theme, including Path Manipulation, Path + Choice, Control Packet Modification or Injection, Reconaissance and + Attacks on Time Sync Mechanisms. 6.1.3. Hot Swap A DetNet network is not expected to be "plug and play" - it is expected that there is some centralized network configuration and control system. However, the ability to "hot swap" components (e.g. due to malfunction) is similar enough to "plug and play" that this kind of behavior may be expected in DetNet networks, depending on the implementation. @@ -1117,44 +1127,44 @@ Similarly if the network was designed to support runtime replacement of a clock device, then presence (or apparent presence) and thus consideration of packets from a new such device could affect the network, or the time sync of the network, for example by initiating a new Best Master Clock selection process. Thus attacks on time sync should be considered when designing hot swap type functionality (see [RFC7384]). 6.1.4. Data Flow Information Models - Data Flow Information Models specific to DetNet networks are - specified by DetNet, and thus are 'new' and thus potentially present - a new attack surface. + Data Flow YANG models specific to DetNet networks are specified by + DetNet, and thus are 'new' and thus potentially present a new attack + surface. 6.1.5. L2 and L3 Integration A DetNet network integrates Layer 2 (bridged) networks (e.g. AVB/TSN LAN) and Layer 3 (routed) networks via the use of well-known protocols such as IP, MPLS-PW, and Ethernet. There are no specific entries in our table, however that does not imply that there could be no relevant attacks related to L2,L3 integration. 6.1.6. End-to-End Delivery Packets sent over DetNet are not to be dropped by the network due to congestion. (Packets may however intentionally be dropped for intended reasons, e.g. per security measures). A Data plane attack may force packets to be dropped, for example a "long" Delay or Replication/Elimination or Flow Modification attack. - The same result might be obtained by a Control plane attack, e.g. + The same result might be obtained by a controller plane attack, e.g. Path Manipulation or Signaling Packet Modification. It may be that such attacks are limited to Internal MITM attackers, but other possibilities should be considered. 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 to be preferred over another path when they should not be (Replication attack), or by Flow Modification, or by Path Choice or Packet Injection. A Time Sync attack could cause a system that was @@ -1167,91 +1177,91 @@ 6.1.7. Proprietary Deterministic Ethernet Networks There are many proprietary non-interoperable deterministic Ethernet- based networks currently available; DetNet is intended to provide an open-standards-based alternative to such networks. In cases where a DetNet intersects with remnants of such networks or their protocols, such as by protocol emulation or access to such a network via a gateway, new attack surfaces can be opened. - For example an Inter-Segment or Control 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 could be used to exploit commands specific to such a protocol, or that are interpreted differently by the different protocols or gateway. 6.1.8. Replacement for Proprietary Fieldbuses There are many proprietary "field buses" used in today's industrial and other industries; DetNet is intended to provide an open- standards-based alternative to such buses. In cases where a DetNet intersects with such fieldbuses or their protocols, such as by protocol emulation or access via a gateway, new attack surfaces can be opened. - For example an Inter-Segment or Control 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 could be used to exploit commands specific to such a protocol, or that are interpreted differently by the different protocols or gateway. 6.1.9. Deterministic vs Best-Effort Traffic Most of the themes described in this document address OT (reserved) - streams - this item is intended to address issues related to IT + DetNet flows - this item is intended to address issues related to IT traffic on a DetNet. DetNet is intended to support coexistence of time-sensitive operational (OT, deterministic) traffic and information (IT, "best effort") traffic on the same ("unified") network. With DetNet, this coexistance will become more common, and mitigations will need to be established. The fact that the IT traffic on a DetNet is limited to a corporate controlled network makes this a less difficult problem compared to being exposed to the open Internet, however this aspect of DetNet security should not be underestimated. 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 - of interfering with OT traffic. Presumably if the stream reservation - and isolation of the DetNet is well-designed (better-designed than - the attack) then interference with OT traffic should not result from - an attack that floods the network with IT traffic. + of interfering with OT traffic. Presumably if the DetNet flow + reservation and isolation of the DetNet is well-designed (better- + designed than the attack) then interference with OT traffic should + 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 resilient to DOS attack, and thus designers must be otherwise prepared to mitigate DOS attacks on IT traffic in a DetNet. 6.1.10. Deterministic Flows Reserved bandwidth data flows (deterministic flows) must provide the allocated bandwidth, and must be isolated from each other. A Spoofing or Inter-segment attack which adds packet traffic to a - bandwidth-reserved stream could cause that stream to occupy more - bandwidth than it is allocated, resulting in interference with other - deterministic flows. + bandwidth-reserved DetNet flow could cause that flow to occupy more + bandwidth than it was allocated, resulting in interference with other + DetNet flows. A Flow Modification or Spoofing or Header Manipulation or Control Packet Modification attack could cause packets from one flow to be directed to another flow, thus breaching isolation between the flows. 6.1.11. Unused Reserved Bandwidth - If bandwidth reservations are made for a stream but the associated - bandwidth is not used at any point in time, that bandwidth is made - available on the network for best-effort traffic. However, note that - security considerations for best-effort traffic on a DetNet network - is out of scope of the present document, provided that such an attack - does not affect performance for DetNet OT traffic. + If bandwidth reservations are made for a DetNet flow but the + associated bandwidth is not used at any point in time, that bandwidth + is made available on the network for best-effort traffic. However, + note that security considerations for best-effort traffic on a DetNet + network is out of scope of the present document, provided that such + an attack does not affect performance for DetNet OT traffic. 6.1.12. Interoperability The DetNet network specifications are intended to enable an ecosystem in which multiple vendors can create interoperable products, thus promoting device diversity and potentially higher numbers of each device manufactured. Given that the DetNet specifications are unambiguously written and that the implementations are accurate, then this should not in and of @@ -1326,34 +1336,35 @@ in the implementations which have not been wrung out by extensive use, particularly in the case of early adopters. Of the attacks we have defined, the ones identified above as relevant to "large" networks seem to be most relevant. 6.1.17. Level of Service A DetNet is expected to provide means to configure the network that include querying network path latency, requesting bounded latency for - a given stream, requesting worst case maximum and/or minimum latency - for a given path or stream, and so on. It is an expected case that - the network cannot provide a given requested service level. In such - cases the network control system should reply that the requested - service level is not available (as opposed to accepting the parameter - but then not delivering the desired behavior). + a given DetNet flow, requesting worst case maximum and/or minimum + latency for a given path or DetNet flow, and so on. It is an + expected case that the network cannot provide a given requested + service level. In such cases the network control system should reply + that the requested service level is not available (as opposed to + accepting the parameter but then not delivering the desired + behavior). - Control 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 could interfere with the process of a user requesting a level of service and/or the network's reply. Reconnaissance could be used to characterize flows and perhaps target - specific flows for attack via the Control plane as noted above. + specific flows for attack via the controller plane as noted above. 6.1.18. Bounded Latency DetNet provides the expectation of guaranteed bounded latency. Delay attacks can cause packets to miss their agreed-upon latency boundaries. Time Sync attacks can corrupt the system's time reference, resulting in missed latency deadlines (with respect to the "correct" time @@ -1363,21 +1374,21 @@ Applications may require "extremely low latency" however depending on the application these may mean very different latency values; for 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 machine. The intent is that the mechanisms for specifying desired latency include wide ranges, and that architecturally there is nothing to prevent arbitrarily low latencies from being implemented in a given network. - Attacks on the Control plane (as described in the Level of Service + Attacks on the controller plane (as described in the Level of Service theme) and Delay and Time attacks (as described in the Bounded Latency theme) both apply here. 6.1.20. Bounded Jitter (Latency Variation) DetNet is expected to provide bounded jitter (packet to packet latency variation). Delay attacks can cause packets to vary in their arrival times, resulting in packet to packet latency variation, thereby violating @@ -1416,44 +1427,39 @@ 6.1.23. Redundant Paths DetNet based systems are expected to be implemented with essentially arbitrarily high reliability/availability. A strategy used by DetNet for providing such extraordinarily high levels of reliability is to provide redundant paths that can be seamlessly switched between, all the while maintaining the required performance of that system. Replication-related attacks are by definition applicable here. - Control plane attacks can also interfere with the configuration of + Controller plane attacks can also interfere with the configuration of redundant paths. 6.1.24. Security Measures A DetNet network must be made secure against devices failures, attackers, misbehaving devices, and so on. Does the threat affect such security measures themselves, e.g. by attacking SW designed to protect against device failure? This is TBD, thus there are no specific entries in our table, however that does not imply that there could be no relevant attacks. 6.2. Attack Types by Use Case Common Theme The following table lists the attacks of Section 3, assigning a number to each type of attack. That number is then used as a short form identifier for the attack in Figure 5. - Editor's note: Is this tabular summary of the above information - useful or necessary in this draft? If we opt to maintain the tables - then the WG needs to validate them for completeness and correctness - after all other draft comments have been addressed. - +--+----------------------------------------+----------------------+ | | Attack | Section | +--+----------------------------------------+----------------------+ | 1|Delay Attack | Section 3.2.1 | +--+----------------------------------------+----------------------+ | 2|DetNet Flow Modification or Spoofing | Section 3.2.2 | +--+----------------------------------------+----------------------+ | 3|Inter-Segment Attack | Section 3.2.3 | +--+----------------------------------------+----------------------+ | 4|Replication: Increased attack surface | Section 3.2.4.1 | @@ -1669,64 +1675,96 @@ Having attended to the conventional aspects of network security it is necessary to attend to the dynamic aspects. The closest experience that the IETF has with securing protocols that are sensitive to manipulation of delay are the two way time transfer protocols (TWTT), which are NTP [RFC5905] and Precision Time Protocol [IEEE1588]. The security requirements for these are described in [RFC7384]. One particular problem that has been observed in operational tests of TWTT protocols is the ability for two closely but not completely - synchronized streams to beat and cause a sudden phase hit to one of - the streams. This can be mitigated by the careful use of a - scheduling system in the underlying packet transport. + 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 + system in the underlying packet transport. Further consideration of protection against dynamic attacks is work in progress. 8. IANA Considerations This memo includes no requests from IANA. 9. Security Considerations The security considerations of DetNet networks are presented throughout this document. -10. Informative References +10. Contributors + + The Editor would like to recognize the contributions of the following + individuals to this draft. + + Andrew J. Hacker (MistIQ Technologies, Inc) + Harrisburg, PA, USA + email ajhacker@mistiqtech.com, + web http://www.mistiqtech.com + + Subir Das (Applied Communication Sciences) + 150 Mount Airy Road, Basking Ridge + New Jersey, 07920, USA + email sdas@appcomsci.com + + John Dowdell (Airbus Defence and Space) + Celtic Springs, Newport, NP10 8FZ, United Kingdom + email john.dowdell.ietf@gmail.com + + Henrik Austad (SINTEF Digital) + Klaebuveien 153, Trondheim, 7037, Norway + email henrik@austad.us + + Norman Finn + email nfinn@nfinnconsulting.com + + Carsten Bormann + +11. Informative References [ARINC664P7] ARINC, "ARINC 664 Aircraft Data Network, Part 7, Avionics Full-Duplex Switched Ethernet Network", 2009. [I-D.ietf-detnet-data-plane-framework] - Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A., - Bryant, S., and J. Korhonen, "DetNet Data Plane - Framework", draft-ietf-detnet-data-plane-framework-03 - (work in progress), October 2019. + Varga, B., Farkas, J., Berger, L., Malis, A., and S. + Bryant, "DetNet Data Plane Framework", draft-ietf-detnet- + data-plane-framework-04 (work in progress), February 2020. + + [I-D.ietf-detnet-flow-information-model] + Farkas, J., Varga, B., Cummings, R., Jiang, Y., and D. + Fedyk, "DetNet Flow Information Model", draft-ietf-detnet- + flow-information-model-07 (work in progress), March 2020. [I-D.ietf-detnet-ip] Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A., - Bryant, S., and J. Korhonen, "DetNet Data Plane: IP", - draft-ietf-detnet-ip-04 (work in progress), November 2019. + and S. Bryant, "DetNet Data Plane: IP", draft-ietf-detnet- + ip-05 (work in progress), February 2020. [I-D.ietf-detnet-ip-over-tsn] Varga, B., Farkas, J., Malis, A., and S. Bryant, "DetNet Data Plane: IP over IEEE 802.1 Time Sensitive Networking - (TSN)", draft-ietf-detnet-ip-over-tsn-01 (work in - progress), October 2019. + (TSN)", draft-ietf-detnet-ip-over-tsn-02 (work in + progress), March 2020. [I-D.ietf-detnet-mpls] Varga, B., Farkas, J., Berger, L., Fedyk, D., Malis, A., Bryant, S., and J. Korhonen, "DetNet Data Plane: MPLS", - draft-ietf-detnet-mpls-04 (work in progress), November - 2019. + draft-ietf-detnet-mpls-05 (work in progress), February + 2020. [I-D.varga-detnet-service-model] Varga, B. and J. Farkas, "DetNet Service Model", draft- varga-detnet-service-model-02 (work in progress), May 2017. [IEEE1588] IEEE, "IEEE 1588 Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems Version 2", 2008. @@ -1739,25 +1777,20 @@ [IEEE802.1Qch-2017] IEEE Standards Association, "IEEE Standard for Local and metropolitan area networks--Bridges and Bridged Networks-- Amendment 29: Cyclic Queuing and Forwarding", 2017, . [MIRAI] krebsonsecurity.com, "https://krebsonsecurity.com/2016/10/ hacked-cameras-dvrs-powered-todays-massive-internet- outage/", 2016. - [RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., - and W. Weiss, "An Architecture for Differentiated - Services", RFC 2475, DOI 10.17487/RFC2475, December 1998, - . - [RFC3552] Rescorla, E. and B. Korver, "Guidelines for Writing RFC Text on Security Considerations", BCP 72, RFC 3552, DOI 10.17487/RFC3552, July 2003, . [RFC3931] Lau, J., Ed., Townsley, M., Ed., and I. Goyret, Ed., "Layer Two Tunneling Protocol - Version 3 (L2TPv3)", RFC 3931, DOI 10.17487/RFC3931, March 2005, . @@ -1817,57 +1850,20 @@ "Deterministic Networking Architecture", RFC 8655, DOI 10.17487/RFC8655, October 2019, . Authors' Addresses Tal Mizrahi Huawei Network.IO Innovation Lab Email: tal.mizrahi.phd@gmail.com + Ethan Grossman (editor) Dolby Laboratories, Inc. 1275 Market Street San Francisco, CA 94103 USA Phone: +1 415 645 4726 Email: ethan.grossman@dolby.com URI: http://www.dolby.com - - Andrew J. Hacker - MistIQ Technologies, Inc - - Harrisburg, PA - USA - - Phone: - Email: ajhacker@mistiqtech.com - URI: http://www.mistiqtech.com - - Subir Das - Applied Communication Sciences - 150 Mount Airy Road, Basking Ridge - New Jersey, 07920 - USA - - Email: sdas@appcomsci.com - - John Dowdell - Airbus Defence and Space - Celtic Springs - Newport NP10 8FZ - United Kingdom - - Email: john.dowdell.ietf@gmail.com - - Henrik Austad - SINTEF Digital - Klaebuveien 153 - Trondheim 7037 - Norway - - Email: henrik@austad.us - Norman Finn - Huawei - - Email: norman.finn@mail01.huawei.com