draft-ietf-dots-requirements-09.txt   draft-ietf-dots-requirements-10.txt 
DOTS A. Mortensen DOTS A. Mortensen
Internet-Draft Arbor Networks Internet-Draft Arbor Networks
Intended status: Informational R. Moskowitz Intended status: Informational R. Moskowitz
Expires: June 22, 2018 Huawei Expires: July 6, 2018 Huawei
T. Reddy T. Reddy
McAfee, Inc. McAfee, Inc.
December 19, 2017 January 02, 2018
Distributed Denial of Service (DDoS) Open Threat Signaling Requirements Distributed Denial of Service (DDoS) Open Threat Signaling Requirements
draft-ietf-dots-requirements-09 draft-ietf-dots-requirements-10
Abstract Abstract
This document defines the requirements for the Distributed Denial of This document defines the requirements for the Distributed Denial of
Service (DDoS) Open Threat Signaling (DOTS) protocols coordinating Service (DDoS) Open Threat Signaling (DOTS) protocols coordinating
attack response against DDoS attacks. attack response against DDoS attacks.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 22, 2018. This Internet-Draft will expire on July 6, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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2.4. Security Requirements . . . . . . . . . . . . . . . . . . 13 2.4. Security Requirements . . . . . . . . . . . . . . . . . . 13
2.5. Data Model Requirements . . . . . . . . . . . . . . . . . 15 2.5. Data Model Requirements . . . . . . . . . . . . . . . . . 15
3. Congestion Control Considerations . . . . . . . . . . . . . . 16 3. Congestion Control Considerations . . . . . . . . . . . . . . 16
3.1. Signal Channel . . . . . . . . . . . . . . . . . . . . . 16 3.1. Signal Channel . . . . . . . . . . . . . . . . . . . . . 16
3.2. Data Channel . . . . . . . . . . . . . . . . . . . . . . 16 3.2. Data Channel . . . . . . . . . . . . . . . . . . . . . . 16
4. Security Considerations . . . . . . . . . . . . . . . . . . . 16 4. Security Considerations . . . . . . . . . . . . . . . . . . . 16
5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 17 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.1. Normative References . . . . . . . . . . . . . . . . . . 17 7.1. Normative References . . . . . . . . . . . . . . . . . . 17
7.2. Informative References . . . . . . . . . . . . . . . . . 18 7.2. Informative References . . . . . . . . . . . . . . . . . 19
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 19
1. Introduction 1. Introduction
1.1. Context and Motivation 1.1. Context and Motivation
Distributed Denial of Service (DDoS) attacks continue to plague Distributed Denial of Service (DDoS) attacks continue to plague
network operators around the globe, from Tier-1 service providers on network operators around the globe, from Tier-1 service providers on
down to enterprises and small businesses. Attack scale and frequency down to enterprises and small businesses. Attack scale and frequency
similarly have continued to increase, in part as a result of software similarly have continued to increase, in part as a result of software
vulnerabilities leading to reflection and amplification attacks. vulnerabilities leading to reflection and amplification attacks.
Once-staggering attack traffic volume is now the norm, and the impact High-volume attacks saturating inbound links are now common, and the
of larger-scale attacks attract the attention of international press impact of larger-scale attacks attract the attention of international
agencies. press agencies.
The greater impact of contemporary DDoS attacks has led to increased The greater impact of contemporary DDoS attacks has led to increased
focus on coordinated attack response. Many institutions and focus on coordinated attack response. Many institutions and
enterprises lack the resources or expertise to operate on-premises enterprises lack the resources or expertise to operate on-premises
attack mitigation solutions themselves, or simply find themselves attack mitigation solutions themselves, or simply find themselves
constrained by local bandwidth limitations. To address such gaps, constrained by local bandwidth limitations. To address such gaps,
security service providers have begun to offer on-demand traffic security service providers have begun to offer on-demand traffic
scrubbing services, which aim to separate the DDoS traffic from scrubbing services, which aim to separate the DDoS traffic from
legitimate traffic and forward only the latter. Today each such legitimate traffic and forward only the latter. Today each such
service offers a proprietary invocation interface for subscribers to service offers a proprietary invocation interface for subscribers to
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DDoS: A distributed denial-of-service attack, in which traffic DDoS: A distributed denial-of-service attack, in which traffic
originating from multiple sources are directed at a target on a originating from multiple sources are directed at a target on a
network. DDoS attacks are intended to cause a negative impact on network. DDoS attacks are intended to cause a negative impact on
the availability of servers, services, applications, and/or other the availability of servers, services, applications, and/or other
functionality of an attack target. Denial-of-service functionality of an attack target. Denial-of-service
considerations are discussed in detail in [RFC4732]. considerations are discussed in detail in [RFC4732].
DDoS attack target: A network connected entity with a finite set of DDoS attack target: A network connected entity with a finite set of
resources, such as network bandwidth, memory or CPU, that is the resources, such as network bandwidth, memory or CPU, that is the
focus of a DDoS attack. Potential targets include (but not target of a DDoS attack. Potential targets include (but are not
limited to) network elements, network links, servers, and limited to) network elements, network links, servers, and
services. services.
DDoS attack telemetry: Collected measurements and behavioral DDoS attack telemetry: Collected measurements and behavioral
characteristics defining the nature of a DDoS attack. characteristics defining the nature of a DDoS attack.
Countermeasure: An action or set of actions taken to recognize and Countermeasure: An action or set of actions taken to recognize and
filter out DDoS attack traffic while passing legitimate traffic to filter out DDoS attack traffic while passing legitimate traffic to
the attack target. the attack target.
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feedback to the requesting DOTS client. A DOTS server may also be feedback to the requesting DOTS client. A DOTS server may also be
colocated with a mitigator. colocated with a mitigator.
DOTS agent: Any DOTS-aware software module capable of participating DOTS agent: Any DOTS-aware software module capable of participating
in a DOTS signal or data channel. It can be a DOTS client, DOTS in a DOTS signal or data channel. It can be a DOTS client, DOTS
server, or, as a logical agent, a DOTS gateway. server, or, as a logical agent, a DOTS gateway.
DOTS gateway: A DOTS-aware software module resulting from the DOTS gateway: A DOTS-aware software module resulting from the
logical concatenation of a DOTS server and a DOTS client, logical concatenation of a DOTS server and a DOTS client,
analogous to a Session Initiation Protocol (SIP) [RFC3261] Back- analogous to a Session Initiation Protocol (SIP) [RFC3261] Back-
to-Back User Agent (B2BUA) [RFC7092]. Client-side DOTS gateways to-Back User Agent (B2BUA) [RFC7092]. A DOTS gateway has a
are DOTS gateways that are in the DOTS client's domain, while client-facing side, which behaves as a DOTS server for downstream
server-side DOTS gateways denote DOTS gateways that are in the clients, and a server-facing side, which performs the role of DOTS
DOTS server's domain. DOTS gateways are discussed in detail in client to upstream DOTS servers. Client-domain DOTS gateways are
DOTS gateways that are in the DOTS client's domain, while server-
domain DOTS gateways denote DOTS gateways that are in the DOTS
server's domain. DOTS gateways are described further in
[I-D.ietf-dots-architecture]. [I-D.ietf-dots-architecture].
Signal channel: A bidirectional, mutually authenticated Signal channel: A bidirectional, mutually authenticated
communication channel between two DOTS agents characterized by communication channel between two DOTS agents characterized by
resilience even in conditions leading to severe packet loss, such resilience even in conditions leading to severe packet loss, such
as a volumetric DDoS attack causing network congestion. as a volumetric DDoS attack causing network congestion.
DOTS signal: A concise authenticated status/control message DOTS signal: A concise authenticated status/control message
transmitted between DOTS agents, used to indicate client's need transmitted between DOTS agents, used to indicate the client's
for mitigation, as well as to convey the status of any requested need for mitigation, as well as to convey the status of any
mitigation. requested mitigation.
Heartbeat: A message transmitted between DOTS agents over the signal Heartbeat: A message transmitted between DOTS agents over the signal
channel, used as a keep-alive and to measure peer health. channel, used as a keep-alive and to measure peer health.
Data channel: A secure communication layer between two DOTS agents Data channel: A secure communication layer between two DOTS agents
used for infrequent bulk exchange of data not easily or used for infrequent bulk exchange of data not easily or
appropriately communicated through the signal channel under attack appropriately communicated through the signal channel under attack
conditions. conditions.
Filter: A specification of a matching network traffic flow or set of Filter: A specification of a matching network traffic flow or set of
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DOTS; specifically, to prevent DDoS mitigation in response to DOTS DOTS; specifically, to prevent DDoS mitigation in response to DOTS
signaling from becoming a new form of attack. In order to provide signaling from becoming a new form of attack. In order to provide
this level of protection, DOTS agents must have a way to negotiate this level of protection, DOTS agents must have a way to negotiate
and agree upon the terms of protocol security. Attacks against the and agree upon the terms of protocol security. Attacks against the
transport protocol should not offer a means of attack against the transport protocol should not offer a means of attack against the
message confidentiality, integrity and authenticity. message confidentiality, integrity and authenticity.
The DOTS server and client must also have some common method of The DOTS server and client must also have some common method of
defining the scope of any mitigation performed by a mitigator, as defining the scope of any mitigation performed by a mitigator, as
well as making adjustments to other commonly configurable features, well as making adjustments to other commonly configurable features,
such as listen port numbers, exchanging black- and white-lists, and such as targeted port numbers, exchanging black- and white-lists, and
so on. so on.
Finally, DOTS should be sufficiently extensible to meet future needs Finally, DOTS should be sufficiently extensible to meet future needs
in coordinated attack defense, although this consideration is in coordinated attack defense, although this consideration is
necessarily superseded by the other operational requirements. necessarily superseded by the other operational requirements.
2.1. General Requirements 2.1. General Requirements
GEN-001 Extensibility: Protocols and data models developed as part GEN-001 Extensibility: Protocols and data models developed as part
of DOTS MUST be extensible in order to keep DOTS adaptable to of DOTS MUST be extensible in order to keep DOTS adaptable to
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designed to maximize the probability of signal delivery even under designed to maximize the probability of signal delivery even under
the severely constrained network conditions imposed by particular the severely constrained network conditions imposed by particular
attack traffic. The protocol MUST be resilient, that is, continue attack traffic. The protocol MUST be resilient, that is, continue
operating despite message loss and out-of-order or redundant operating despite message loss and out-of-order or redundant
message delivery. In support of signaling protocol robustness, message delivery. In support of signaling protocol robustness,
DOTS signals SHOULD be conveyed over a transport not susceptible DOTS signals SHOULD be conveyed over a transport not susceptible
to Head of Line Blocking. to Head of Line Blocking.
GEN-003 Bidirectionality: To support peer health detection, to GEN-003 Bidirectionality: To support peer health detection, to
maintain an open signal channel, and to increase the probability maintain an open signal channel, and to increase the probability
of signal delivery during attack, the signal channel MUST be of signal delivery during an attack, the signal channel MUST be
bidirectional, with client and server transmitting signals to each bidirectional, with client and server transmitting signals to each
other at regular intervals, regardless of any client request for other at regular intervals, regardless of any client request for
mitigation. Unidirectional messages MUST be supported within the mitigation. Unidirectional messages MUST be supported within the
bidirectional signal channel to allow for unsolicited message bidirectional signal channel to allow for unsolicited message
delivery, enabling asynchronous notifications between DOTS agents. delivery, enabling asynchronous notifications between DOTS agents.
GEN-004 Bulk Data Exchange: Infrequent bulk data exchange between GEN-004 Bulk Data Exchange: Infrequent bulk data exchange between
DOTS agents can also significantly augment attack response DOTS agents can also significantly augment attack response
coordination, permitting such tasks as population of black- or coordination, permitting such tasks as population of black- or
white-listed source addresses; address or prefix group aliasing; white-listed source addresses; address or prefix group aliasing;
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agents SHOULD assume a PMTU of 1280 bytes. If IPv4 support on agents SHOULD assume a PMTU of 1280 bytes. If IPv4 support on
legacy or otherwise unusual networks is a consideration and PMTU legacy or otherwise unusual networks is a consideration and PMTU
is unknown, DOTS implementations MAY rely on a PMTU of 576 bytes, is unknown, DOTS implementations MAY rely on a PMTU of 576 bytes,
as discussed in [RFC0791] and [RFC1122]. as discussed in [RFC0791] and [RFC1122].
SIG-003 Channel Health Monitoring: DOTS agents MUST support exchange SIG-003 Channel Health Monitoring: DOTS agents MUST support exchange
of heartbeat messages over the signal channel to monitor channel of heartbeat messages over the signal channel to monitor channel
health. Peer DOTS agents SHOULD regularly send heartbeats to each health. Peer DOTS agents SHOULD regularly send heartbeats to each
other while a mitigation request is active. The heartbeat other while a mitigation request is active. The heartbeat
interval during active mitigation is not specified, but SHOULD be interval during active mitigation is not specified, but SHOULD be
frequent enough to maintain any on-path NAT bindings during frequent enough to maintain any on-path NAT or Firewall bindings
mitigation. during mitigation.
To support scenarios in which loss of heartbeat is used to trigger To support scenarios in which loss of heartbeat is used to trigger
mitigation, and to keep the channel active, DOTS clients MAY mitigation, and to keep the channel active, DOTS clients MAY
solicit heartbeat exchanges after successful mutual solicit heartbeat exchanges after successful mutual
authentication. When DOTS agents are exchanging heartbeats and no authentication. When DOTS agents are exchanging heartbeats and no
mitigation request is active, either agent MAY request changes to mitigation request is active, either agent MAY request changes to
the heartbeat rate. For example, a DOTS server might want to the heartbeat rate. For example, a DOTS server might want to
reduce heartbeat frequency or cease heartbeat exchanges when an reduce heartbeat frequency or cease heartbeat exchanges when an
active DOTS client has not requested mitigation, in order to active DOTS client has not requested mitigation, in order to
control load. control load.
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Following mutual authentication, a signal channel MUST be Following mutual authentication, a signal channel MUST be
considered active until a DOTS agent explicitly ends the session, considered active until a DOTS agent explicitly ends the session,
or either DOTS agent fails to receive heartbeats from the other or either DOTS agent fails to receive heartbeats from the other
after a mutually agreed upon retransmission procedure has been after a mutually agreed upon retransmission procedure has been
exhausted. Because heartbeat loss is much more likely during exhausted. Because heartbeat loss is much more likely during
volumetric attack, DOTS agents SHOULD avoid signal channel volumetric attack, DOTS agents SHOULD avoid signal channel
termination when mitigation is active and heartbeats are not termination when mitigation is active and heartbeats are not
received by either DOTS agent for an extended period. In such received by either DOTS agent for an extended period. In such
circumstances, DOTS clients MAY attempt to reestablish the signal circumstances, DOTS clients MAY attempt to reestablish the signal
channel, but SHOULD continue to send heartbeats so that the DOTS channel, but SHOULD continue to send heartbeats so that the DOTS
server knows the session is still partially alive. DOTS servers server knows the session is still alive. DOTS servers SHOULD
SHOULD monitor the attack, using feedback from the mitigator and monitor the attack, using feedback from the mitigator and other
other available sources, and MAY use the absence of attack traffic available sources, and MAY use the absence of attack traffic and
and lack of client heartbeats as an indication the signal channel lack of client heartbeats as an indication the signal channel is
is defunct. defunct.
SIG-004 Channel Redirection: In order to increase DOTS operational SIG-004 Channel Redirection: In order to increase DOTS operational
flexibility and scalability, DOTS servers SHOULD be able to flexibility and scalability, DOTS servers SHOULD be able to
redirect DOTS clients to another DOTS server at any time. DOTS redirect DOTS clients to another DOTS server at any time. DOTS
clients MUST NOT assume the redirection target DOTS server shares clients MUST NOT assume the redirection target DOTS server shares
security state with the redirecting DOTS server. DOTS clients MAY security state with the redirecting DOTS server. DOTS clients MAY
attempt abbreviated security negotiation methods supported by the attempt abbreviated security negotiation methods supported by the
protocol, such as DTLS session resumption, but MUST be prepared to protocol, such as DTLS session resumption, but MUST be prepared to
negotiate new security state with the redirection target DOTS negotiate new security state with the redirection target DOTS
server. server.
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* IPv4 prefixes in CIDR notation [RFC4632] * IPv4 prefixes in CIDR notation [RFC4632]
* IPv6 prefixes [RFC4291][RFC5952] * IPv6 prefixes [RFC4291][RFC5952]
* Domain names [RFC1035] * Domain names [RFC1035]
The following mitigation scope types are OPTIONAL: The following mitigation scope types are OPTIONAL:
* Uniform Resource Identifiers [RFC3986] * Uniform Resource Identifiers [RFC3986]
DOTS servers MUST be able to resolve domain names and URIs. How DOTS servers MUST be able to resolve domain names and (when
name resolution is managed on the DOTS server is implementation- supported) URIs. How name resolution is managed on the DOTS
specific. server is implementation-specific.
DOTS agents MUST support mitigation scope aliases, allowing DOTS DOTS agents MUST support mitigation scope aliases, allowing DOTS
clients and servers to refer to collections of protected resources clients and servers to refer to collections of protected resources
by an opaque identifier created through the data channel, direct by an opaque identifier created through the data channel, direct
configuration, or other means. Domain name and URI mitigation configuration, or other means. Domain name and URI mitigation
scopes may be thought of as a form of scope alias, in which the scopes may be thought of as a form of scope alias, in which the
addresses to which the domain name or URI resolve represent the addresses to which the domain name or URI resolve represent the
full scope of the mitigation. full scope of the mitigation.
If there is additional information available narrowing the scope If there is additional information available narrowing the scope
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If UDP is used as the transport for the DOTS signal channel, all If UDP is used as the transport for the DOTS signal channel, all
considerations in "Middlebox Traversal Guidelines" in [RFC8085] considerations in "Middlebox Traversal Guidelines" in [RFC8085]
apply to DOTS. Regardless of transport, DOTS protocols MUST apply to DOTS. Regardless of transport, DOTS protocols MUST
follow established best common practices (BCPs) for NAT traversal. follow established best common practices (BCPs) for NAT traversal.
2.3. Data Channel Requirements 2.3. Data Channel Requirements
The data channel is intended to be used for bulk data exchanges The data channel is intended to be used for bulk data exchanges
between DOTS agents. Unlike the signal channel, which must operate between DOTS agents. Unlike the signal channel, which must operate
nominally even when confronted with signal degradation due to packet nominally even when confronted with signal degradation due to
loss, the data channel is not expected to be constructed to deal with significant packet loss, the data channel is not expected to be
attack conditions. As the primary function of the data channel is constructed to deal with attack conditions. As the primary function
data exchange, a reliable transport is required in order for DOTS of the data channel is data exchange, a reliable transport is
agents to detect data delivery success or failure. required in order for DOTS agents to detect data delivery success or
failure.
The DOTS data channel protocol MUST be extensible. We anticipate the The DOTS data channel protocol MUST be extensible. We anticipate the
data channel will be used for such purposes as configuration or data channel will be used for such purposes as configuration or
resource discovery. For example, a DOTS client may submit to a DOTS resource discovery. For example, a DOTS client may submit to a DOTS
server a collection of prefixes it wants to refer to by alias when server a collection of prefixes it wants to refer to by alias when
requesting mitigation, to which the server would respond with a requesting mitigation, to which the server would respond with a
success status and the new prefix group alias, or an error status and success status and the new prefix group alias, or an error status and
message in the event the DOTS client's data channel request failed. message in the event the DOTS client's data channel request failed.
The transactional nature of such data exchanges suggests a separate The transactional nature of such data exchanges suggests a separate
set of requirements for the data channel, while the potentially set of requirements for the data channel, while the potentially
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in cryptanalysis and traffic analysis, DOTS agents MUST be able to in cryptanalysis and traffic analysis, DOTS agents MUST be able to
negotiate the terms and mechanisms of protocol security, subject negotiate the terms and mechanisms of protocol security, subject
to the interoperability and signal message size requirements to the interoperability and signal message size requirements
above. above.
While the interfaces between downstream DOTS server and upstream While the interfaces between downstream DOTS server and upstream
DOTS client within a DOTS gateway are implementation-specific, DOTS client within a DOTS gateway are implementation-specific,
those interfaces nevertheless MUST provide security equivalent to those interfaces nevertheless MUST provide security equivalent to
that of the signal channels bridged by gateways in the signaling that of the signal channels bridged by gateways in the signaling
path. For example, when a DOTS gateway consisting of a DOTS path. For example, when a DOTS gateway consisting of a DOTS
server and DOTS client is running on the same logical device, they server and DOTS client is running on the same logical device, the
must be within the same process security boundary. two DOTS agents could be implemented within the same process
security boundary.
SEC-003 Message Replay Protection: To prevent a passive attacker SEC-003 Message Replay Protection: To prevent a passive attacker
from capturing and replaying old messages, and thereby potentially from capturing and replaying old messages, and thereby potentially
disrupting or influencing the network policy of the receiving DOTS disrupting or influencing the network policy of the receiving DOTS
agent's domain, DOTS protocols MUST provide a method for replay agent's domain, DOTS protocols MUST provide a method for replay
detection and prevention. detection and prevention.
Within the signal channel, messages MUST be uniquely identified Within the signal channel, messages MUST be uniquely identified
such that replayed or duplicated messages may be detected and such that replayed or duplicated messages can be detected and
discarded. Unique mitigation requests MUST be processed at most discarded. Unique mitigation requests MUST be processed at most
once. once.
SEC-004 Authorization: DOTS servers MUST authorize all messages from SEC-004 Authorization: DOTS servers MUST authorize all messages from
DOTS clients which pertain to mitigation, configuration, DOTS clients which pertain to mitigation, configuration,
filtering, or status. filtering, or status.
DOTS servers MUST reject mitigation requests with scopes which the DOTS servers MUST reject mitigation requests with scopes which the
DOTS client is not authorized to manage. DOTS client is not authorized to manage.
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