draft-ietf-dots-requirements-06.txt   draft-ietf-dots-requirements-07.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: January 4, 2018 HTT Consulting Expires: May 3, 2018 Huawei
T. Reddy T. Reddy
McAfee, Inc. McAfee, Inc.
July 03, 2017 October 30, 2017
Distributed Denial of Service (DDoS) Open Threat Signaling Requirements Distributed Denial of Service (DDoS) Open Threat Signaling Requirements
draft-ietf-dots-requirements-06 draft-ietf-dots-requirements-07
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
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on January 4, 2018. This Internet-Draft will expire on May 3, 2018.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Context and Motivation . . . . . . . . . . . . . . . . . 2 1.1. Context and Motivation . . . . . . . . . . . . . . . . . 2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5 2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. General Requirements . . . . . . . . . . . . . . . . . . 7 2.1. General Requirements . . . . . . . . . . . . . . . . . . 7
2.2. Signal Channel Requirements . . . . . . . . . . . . . . . 7 2.2. Signal Channel Requirements . . . . . . . . . . . . . . . 8
2.3. Data Channel Requirements . . . . . . . . . . . . . . . . 11 2.3. Data Channel Requirements . . . . . . . . . . . . . . . . 12
2.4. Security requirements . . . . . . . . . . . . . . . . . . 13 2.4. Security requirements . . . . . . . . . . . . . . . . . . 13
2.5. Data Model Requirements . . . . . . . . . . . . . . . . . 14 2.5. Data Model Requirements . . . . . . . . . . . . . . . . . 15
3. Congestion Control Considerations . . . . . . . . . . . . . . 15 3. Congestion Control Considerations . . . . . . . . . . . . . . 16
3.1. Signal Channel . . . . . . . . . . . . . . . . . . . . . 15 3.1. Signal Channel . . . . . . . . . . . . . . . . . . . . . 16
3.2. Data Channel . . . . . . . . . . . . . . . . . . . . . . 15 3.2. Data Channel . . . . . . . . . . . . . . . . . . . . . . 16
4. Security Considerations . . . . . . . . . . . . . . . . . . . 15 4. Security Considerations . . . . . . . . . . . . . . . . . . . 16
5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 16 5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 17
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 17
7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 16 7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.1. 04 revision . . . . . . . . . . . . . . . . . . . . . . . 16 7.1. 04 revision . . . . . . . . . . . . . . . . . . . . . . . 17
7.2. 03 revision . . . . . . . . . . . . . . . . . . . . . . . 17 7.2. 03 revision . . . . . . . . . . . . . . . . . . . . . . . 18
7.3. 02 revision . . . . . . . . . . . . . . . . . . . . . . . 17 7.3. 02 revision . . . . . . . . . . . . . . . . . . . . . . . 18
7.4. 01 revision . . . . . . . . . . . . . . . . . . . . . . . 17 7.4. 01 revision . . . . . . . . . . . . . . . . . . . . . . . 18
7.5. 00 revision . . . . . . . . . . . . . . . . . . . . . . . 18 7.5. 00 revision . . . . . . . . . . . . . . . . . . . . . . . 19
7.6. Initial revision . . . . . . . . . . . . . . . . . . . . 18 7.6. Initial revision . . . . . . . . . . . . . . . . . . . . 19
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 18 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Normative References . . . . . . . . . . . . . . . . . . 18 8.1. Normative References . . . . . . . . . . . . . . . . . . 19
8.2. Informative References . . . . . . . . . . . . . . . . . 19 8.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
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.
skipping to change at page 3, line 9 skipping to change at page 3, line 9
agencies. 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 its own interface for subscribers to request attack service offers a proprietary invocation interface for subscribers to
mitigation, tying subscribers to proprietary signaling request attack mitigation, tying subscribers to proprietary signaling
implementations while also limiting the subset of network elements implementations while also limiting the subset of network elements
capable of participating in the attack response. As a result of capable of participating in the attack mitigation. As a result of
signaling interface incompatibility, attack responses may be signaling interface incompatibility, attack responses may be
fragmentary or otherwise incomplete, leaving key players in the fragmentary or otherwise incomplete, leaving key players in the
attack path unable to assist in the defense. attack path unable to assist in the defense.
The lack of a common method to coordinate a real-time response among The lack of a common method to coordinate a real-time response among
involved actors and network domains inhibits the speed and involved actors and network domains inhibits the speed and
effectiveness of DDoS attack mitigation. This document describes the effectiveness of DDoS attack mitigation. This document describes the
required characteristics of a protocol enabling requests for DDoS required characteristics of protocols enabling requests for DDoS
attack mitigation, reducing attack impact and leading to more attack mitigation, reducing attack impact and leading to more
efficient defensive strategies. efficient defensive strategies.
DOTS communicates the need for defensive action in anticipation of or DDoS Open Threat Signaling (DOTS) communicates the need for defensive
in response to an attack, but does not dictate the form any defensive action in anticipation of or in response to an attack, but does not
action takes. DOTS supplements calls for help with pertinent details dictate the form any defensive action takes. DOTS supplements calls
about the detected attack, allowing entities participating in DOTS to for help with pertinent details about the detected attack, allowing
form ad hoc, adaptive alliances against DDoS attacks as described in entities participating in DOTS to form ad hoc, adaptive alliances
the DOTS use cases [I-D.ietf-dots-use-cases]. The requirements in against DDoS attacks as described in the DOTS use cases
this document are derived from those use cases and [I-D.ietf-dots-use-cases]. The requirements in this document are
[I-D.ietf-dots-architecture]. derived from those use cases and [I-D.ietf-dots-architecture].
1.2. Terminology 1.2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
This document adopts the following terms: This document adopts the following terms:
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 network focus of a DDoS attack. Potential targets include (but not
elements, network links, servers, and services. limited to) network elements, network links, servers, and
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.
Mitigation: A set of countermeasures enforced against traffic Mitigation: A set of countermeasures enforced against traffic
destined for the target or targets of a detected or reported DDoS destined for the target or targets of a detected or reported DDoS
attack, where countermeasure enforcement is managed by an entity attack, where countermeasure enforcement is managed by an entity
in the network path between attack sources and the attack target. in the network path between attack sources and the attack target.
Mitigation methodology is out of scope for this document. Mitigation methodology is out of scope for this document.
Mitigator: An entity, typically a network element, capable of Mitigator: An entity, typically a network element, capable of
performing mitigation of a detected or reported DDoS attack. For performing mitigation of a detected or reported DDoS attack. For
the purposes of this document, this entity is a black box capable the purposes of this document, this entity is a black box capable
of mitigation, making no assumptions about availability or design of mitigation, making no assumptions about availability or design
of countermeasures, nor about the programmable interface between of countermeasures, nor about the programmable interface(s)
this entity and other network elements. The mitigator and DOTS between this entity and other network elements. The mitigator and
server are assumed to belong to the same administrative entity. invoked DOTS server are assumed to belong to the same
administrative entity.
DOTS client: A DOTS-aware software module responsible for requesting DOTS client: A DOTS-aware software module responsible for requesting
attack response coordination with other DOTS-aware elements. attack response coordination with other DOTS-aware elements.
DOTS server: A DOTS-aware software module handling and responding to DOTS server: A DOTS-aware software module handling and responding to
messages from DOTS clients. The DOTS server SHOULD enable messages from DOTS clients. The DOTS server enables mitigation on
mitigation on behalf of the DOTS client, if requested, by behalf of the DOTS client, if requested, by communicating the DOTS
communicating the DOTS client's request to the mitigator and client's request to the mitigator and returning selected mitigator
returning selected mitigator feedback to the requesting DOTS feedback to the requesting DOTS client. A DOTS server may also be
client. A DOTS server MAY also be 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. in a DOTS signal or data channel. It can be a DOTS client, DOTS
server, or, as a logical agent, a DOTS gateway.
DOTS gateway: A logical DOTS agent resulting from the logical DOTS gateway: A DOTS-aware software module resulting from the
concatenation of a DOTS server and a DOTS client, analogous to a logical concatenation of a DOTS server and a DOTS client,
SIP Back-to-Back User Agent (B2BUA) [RFC3261]. DOTS gateways are analogous to a Session Initiation Protocol (SIP) [RFC3261] Back-
discussed in detail in [I-D.ietf-dots-architecture]. to-Back User Agent (B2BUA) [RFC7092]. Client-side DOTS gateways
are DOTS gateways that are in the DOTS client's domain, while
server-side DOTS gateways denote DOTS gateways that are in the
DOTS server's domain. DOTS gateways are discussed in detail in
[I-D.ietf-dots-architecture].
Signal channel: A bidirectional, mutually authenticated Signal channel: A bidirectional, mutually authenticated
communication channel between 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 client's need
for mitigation, as well as to convey the status of any requested for mitigation, as well as to convey the status of any requested
mitigation. 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.
Client signal: A message sent from a DOTS client to a DOTS server Data channel: A secure communication layer between two DOTS agents
over the signal channel, indicating the DOTS client's need for used for infrequent bulk exchange of data not easily or
mitigation, as well as the scope of any requested mitigation, appropriately communicated through the signal channel under attack
optionally including additional attack details to supplement conditions.
server-initiated mitigation.
Server signal: A message sent from a DOTS server to a DOTS client
over the signal channel. Note that a server signal is not a
response to client signal, but a DOTS server-initiated status
message sent to DOTS clients with which the server has established
signal channels.
Data channel: A secure communication layer between DOTS clients and
DOTS servers used for infrequent bulk exchange of data not easily
or appropriately communicated through the signal channel under
attack conditions.
Filter: A policy matching a network traffic flow or set of flows and Filter: A specification of a matching network traffic flow or set of
rate-limiting or discarding matching traffic. flows. The filter will typically have a policy associated with
it, e.g., rate-limiting or discarding matching traffic.
Blacklist: A filter list of addresses, prefixes and/or other Blacklist: A filter list of addresses, prefixes, and/or other
identifiers indicating sources from which traffic should be identifiers indicating sources from which traffic should be
blocked, regardless of traffic content. blocked, regardless of traffic content.
Whitelist: A list of addresses, prefixes and/or other identifiers Whitelist: A list of addresses, prefixes, and/or other identifiers
from indicating sources from which traffic should always be indicating sources from which traffic should always be allowed,
allowed, regardless of contradictory data gleaned in a detected regardless of contradictory data gleaned in a detected attack.
attack.
Multi-homed DOTS client: A DOTS client exchanging messages with Multi-homed DOTS client: A DOTS client exchanging messages with
multiple DOTS servers, each in a separate administrative domain. multiple DOTS servers, each in a separate administrative domain.
2. Requirements 2. Requirements
This section describes the required features and characteristics of This section describes the required features and characteristics of
the DOTS protocol. the DOTS protocol.
DOTS is an advisory protocol. An active DDoS attack against the DOTS is an advisory protocol. An active DDoS attack against the
entity controlling the DOTS client need not be present before entity controlling the DOTS client need not be present before
establishing a communication channel between DOTS agents. Indeed, establishing a communication channel between DOTS agents. Indeed,
establishing a relationship with peer DOTS agents during normal establishing a relationship with peer DOTS agents during normal
network conditions provides the foundation for more rapid attack network conditions provides the foundation for more rapid attack
response against future attacks, as all interactions setting up DOTS, response against future attacks, as all interactions setting up DOTS,
including any business or service level agreements, are already including any business or service level agreements, are already
complete. complete. Peer DOTS agents are provisioned to a DOTS client using a
variety of manual or dynamic methods.
The DOTS protocol must at a minimum make it possible for a DOTS The DOTS protocol must at a minimum make it possible for a DOTS
client to request a mitigator's aid mounting a defense, coordinated client to request a mitigator's aid mounting a defense, coordinated
by a DOTS server, against a suspected attack, signaling within or by a DOTS server, against a suspected attack, signaling within or
between domains as requested by local operators. DOTS clients should between domains as requested by local operators. DOTS clients should
similarly be able to withdraw aid requests. DOTS requires no similarly be able to withdraw aid requests. DOTS requires no
justification from DOTS clients for requests for help, nor do DOTS justification from DOTS clients for requests for help, nor do DOTS
clients need to justify withdrawing help requests: the decision is clients need to justify withdrawing help requests: the decision is
local to the DOTS clients' domain. local to the DOTS clients' domain. Multi-homed DOTS clients must be
able to select the appropriate DOTS server(s) to which a mitigation
request is to be sent. Further multi-homing considerations are out
of scope.
Regular feedback between DOTS clients and DOTS server supplement the Regular feedback between DOTS clients and DOTS servers supplement the
defensive alliance by maintaining a common understanding of DOTS defensive alliance by maintaining a common understanding of the DOTS
agent health and activity. Bidirectional communication between DOTS agents' health and activity. Bidirectional communication between
clients and DOTS servers is therefore critical. DOTS clients and DOTS servers is therefore critical.
DOTS protocol implementations face competing operational goals when DOTS protocol implementations face competing operational goals when
maintaining this bidirectional communication stream. On the one maintaining this bidirectional communication stream. On the one
hand, the protocol must be resilient under extremely hostile network hand, the protocol must be resilient under extremely hostile network
conditions, providing continued contact between DOTS agents even as conditions, providing continued contact between DOTS agents even as
attack traffic saturates the link. Such resiliency may be developed attack traffic saturates the link. Such resiliency may be developed
several ways, but characteristics such as small message size, several ways, but characteristics such as small message size,
asynchronous, redundant message delivery and minimal connection asynchronous, redundant message delivery and minimal connection
overhead (when possible given local network policy) will tend to overhead (when possible given local network policy) will tend to
contribute to the robustness demanded by a viable DOTS protocol. contribute to the robustness demanded by a viable DOTS protocol.
Operators of peer DOTS-enabled domains may enable quality- or class- Operators of peer DOTS-enabled domains may enable quality- or class-
of-service traffic tagging to increase the probability of successful of-service traffic tagging to increase the probability of successful
DOTS signal delivery, but DOTS requires no such policies be in place. DOTS signal delivery, but DOTS does not require such policies be in
The DOTS solution indeed must be viable especially in their absence. place. The DOTS solution indeed must be viable especially in their
absence.
On the other hand, DOTS must include protections ensuring message On the other hand, DOTS must include protections ensuring message
confidentiality, integrity and authenticity to keep the protocol from confidentiality, integrity and authenticity to keep the protocol from
becoming another vector for the very attacks it's meant to help fight becoming another vector for the very attacks it's meant to help fight
off. DOTS clients must be able to authenticate DOTS servers, and off. DOTS clients must be able to authenticate DOTS servers, and
vice versa, to avoid exposing new attack surfaces when deploying vice versa, to avoid exposing new attack surfaces when deploying
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 proteection, 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 the mitigator, as defining the scope of any mitigation performed by the mitigator, as
well as making adjustments to other commonly configurable features, well as making adjustments to other commonly configurable features,
such as listen ports, exchanging black- and white-lists, and so on. such as listen port numbers, exchanging black- and white-lists, and
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
operational and proprietary DDoS defenses. Future extensions MUST operational and proprietary DDoS defenses. Future extensions MUST
be backward compatible. DOTS protocols MUST use a version number be backward compatible. DOTS protocols MUST use a version number
system to distinguish protocol revisions. Implementations of system to distinguish protocol revisions. Implementations of
older protocol versions SHOULD ignore information added to DOTS older protocol versions SHOULD ignore information added to DOTS
messages as part of newer protocol versions. messages as part of newer protocol versions.
GEN-002 Resilience and Robustness: The signaling protocol MUST be GEN-002 Resilience and Robustness: The signaling protocol MUST be
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 signaling protocol robustness, DOTS message delivery. In support of signaling protocol robustness,
signals SHOULD be conveyed over a transport not susceptible to DOTS signals SHOULD be conveyed over a transport not susceptible
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 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 agents. delivery, enabling asynchronous notifications between agents.
skipping to change at page 8, line 22 skipping to change at page 8, line 30
transport- or message-level security. transport- or message-level security.
DOTS agents SHOULD attempt to learn the PMTU through mechanisms DOTS agents SHOULD attempt to learn the PMTU through mechanisms
such as Path MTU Discovery [RFC1191] or Packetization Layer Path such as Path MTU Discovery [RFC1191] or Packetization Layer Path
MTU Discovery [RFC4821]. If the PMTU cannot be discovered, DOTS MTU Discovery [RFC4821]. If the PMTU cannot be discovered, DOTS
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: Peer DOTS agents MUST regularly SIG-003 Channel Health Monitoring: DOTS agents MUST support exchange
send heartbeats to each other after mutual authentication in order of heartbeat messages over the signal channel to monitor channel
to keep the DOTS signal channel active. A signal channel MUST be health. Peer DOTS agents SHOULD regularly send heartbeats to each
other while a mitigation request is active. The heartbeat
interval during active mitigation is not specified, but SHOULD be
frequent enough to maintain any on-path NAT bindings during
mitigation.
To support scenarios in which loss of heartbeat is used to trigger
mitigation, and to keep the channel active, DOTS clients MAY
solicit heartbeat exchanges after successful mutual
authentication. When DOTS agents are exchanging heartbeats and no
mitigation request is active, either agent MAY request changes to
the heartbeat rate. For example, a DOTS server might want to
delay or cease heartbeat exchanges when an active DOTS client has
not requested mitigation, in order to control load.
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 timeout period has elapsed. after a mutually agreed upon timeout period has elapsed. Because
heartbeat loss is much more likely during volumetric attack, DOTS
agents SHOULD avoid signal channel termination when mitigation is
active and heartbeats are not received by either DOTS agent for an
extended period. In such circumstances, DOTS clients MAY attempt
to reestablish the signal channel. DOTS servers SHOULD monitor
the attack, using feedback from the mitigator and other available
sources, and MAY use the absence of attack traffic and lack of
client heartbeats as an indication the signal channel is 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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DOTS client's request to stop mitigation. DOTS client's request to stop mitigation.
To protect against route or DNS flapping caused by a client To protect against route or DNS flapping caused by a client
rapidly toggling mitigation, and to dampen the effect of rapidly toggling mitigation, and to dampen the effect of
oscillating attacks, DOTS servers MAY allow mitigation to continue oscillating attacks, DOTS servers MAY allow mitigation to continue
for a limited period after acknowledging a DOTS client's for a limited period after acknowledging a DOTS client's
withdrawal of a mitigation request. During this period, DOTS withdrawal of a mitigation request. During this period, DOTS
server status messages SHOULD indicate that mitigation is active server status messages SHOULD indicate that mitigation is active
but terminating. but terminating.
The active-but-terminating period is initially 30 seconds. If the The initial active-but-terminating period is implementation-
client requests mitigation again before that 30 second window specific, but SHOULD be sufficiently long to absorb latency
elapses, the DOTS server MAY exponentially increase the active- incurred by route propagation. If the client requests mitigation
but-terminating period up to a maximum of 240 seconds (4 minutes). again before the initial active-but-terminating period elapses,
the DOTS server MAY exponentially increase the active-but-
terminating period up to a maximum of 300 seconds (5 minutes).
After the active-but-terminating period elapses, the DOTS server After the active-but-terminating period elapses, the DOTS server
MUST treat the mitigation as terminated, as the DOTS client is no MUST treat the mitigation as terminated, as the DOTS client is no
longer responsible for the mitigation. For example, if there is a longer responsible for the mitigation. For example, if there is a
financial relationship between the DOTS client and server domains, financial relationship between the DOTS client and server domains,
the DOTS client ceases incurring cost at this point. the DOTS client ceases incurring cost at this point.
SIG-006 Mitigation Lifetime: DOTS servers MUST support mitigation SIG-006 Mitigation Lifetime: DOTS servers MUST support mitigation
lifetimes, and MUST terminate a mitigation when the lifetime lifetimes, and MUST terminate a mitigation when the lifetime
elapses. DOTS servers also MUST support renewal of mitigation elapses. DOTS servers also MUST support renewal of mitigation
lifetimes in mitigation requests from DOTS clients, allowing lifetimes in mitigation requests from DOTS clients, allowing
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DOTS clients SHOULD include a mitigation lifetime in all DOTS clients SHOULD include a mitigation lifetime in all
mitigation requests. If a DOTS client does not include a mitigation requests. If a DOTS client does not include a
mitigation lifetime in requests for help sent to the DOTS server, mitigation lifetime in requests for help sent to the DOTS server,
the DOTS server will use a reasonable default as defined by the the DOTS server will use a reasonable default as defined by the
protocol. protocol.
DOTS servers SHOULD support indefinite mitigation lifetimes, DOTS servers SHOULD support indefinite mitigation lifetimes,
enabling architectures in which the mitigator is always in the enabling architectures in which the mitigator is always in the
traffic path to the resources for which the DOTS client is traffic path to the resources for which the DOTS client is
requesting protection. DOTS servers MAY refuse mitigations with requesting protection. DOTS clients MUST be prepared to not be
indefinite lifetimes, for policy reasons. The reasons themselves granted mitigations with indefinite lifetimes. DOTS servers MAY
are out of scope for this document, but MUST be included in the refuse mitigations with indefinite lifetimes, for policy reasons.
mitigation rejection message from the server, per SIG-005. The reasons themselves are out of scope. If the DOTS server does
not grant a mitigation request with an indefinite mitigation
lifetime, it MUST set the lifetime to a value that is configured
locally. That value MUST be returned in a reply to the requesting
DOTS client.
SIG-007 Mitigation Scope: DOTS clients MUST indicate desired SIG-007 Mitigation Scope: DOTS clients MUST indicate desired
mitigation scope. The scope type will vary depending on the mitigation scope. The scope type will vary depending on the
resources requiring mitigation. All DOTS agent implementations resources requiring mitigation. All DOTS agent implementations
MUST support the following required scope types: MUST support the following required scope types:
* IPv4 addresses in dotted quad format * IPv4 addresses in dotted quad format
* IPv4 prefixes in CIDR notation [RFC4632] * IPv4 prefixes in CIDR notation [RFC4632]
skipping to change at page 10, line 44 skipping to change at page 11, line 31
* 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 agents MUST support mitigation scope aliases, allowing DOTS DOTS agents MUST support mitigation scope aliases, allowing DOTS
client and server 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
of any requested attack response, such as targeted port range, of any requested attack response, such as targeted port range,
protocol, or service, DOTS clients SHOULD include that information protocol, or service, DOTS clients SHOULD include that information
in client signals. DOTS clients MAY also include additional in client signals. DOTS clients MAY also include additional
attack details. Such supplemental information is OPTIONAL, and attack details. Such supplemental information is OPTIONAL, and
DOTS servers MAY ignore it when enabling countermeasures on the DOTS servers MAY ignore it when enabling countermeasures on the
mitigator. mitigator.
As an active attack evolves, clients MUST be able to adjust as As an active attack evolves, clients MUST be able to adjust as
necessary the scope of requested mitigation by refining the scope necessary the scope of requested mitigation by refining the scope
of resources requiring mitigation. of resources requiring mitigation.
The DOTS client may obtain the mitigation scope through direct
provisioning or through implementation-specific methods of
discovery. DOTS clients MUST support at least one mechanism to
obtain mitigiation scope.
SIG-008 Mitigation Efficacy: When a mitigation request by a DOTS SIG-008 Mitigation Efficacy: When a mitigation request by a DOTS
client is active, DOTS clients SHOULD transmit a metric of client is active, DOTS clients SHOULD transmit a metric of
perceived mitigation efficacy to the DOTS server. DOTS servers perceived mitigation efficacy to the DOTS server. DOTS servers
MAY use the efficacy metric to adjust countermeasures activated on MAY use the efficacy metric to adjust countermeasures activated on
a mitigator on behalf of a DOTS client. a mitigator on behalf of a DOTS client.
SIG-009 Conflict Detection and Notification: Multiple DOTS clients SIG-009 Conflict Detection and Notification: Multiple DOTS clients
controlled by a single administrative entity may send conflicting controlled by a single administrative entity may send conflicting
mitigation requests for pool of protected resources , as a result mitigation requests for pools of protected resources as a result
of misconfiguration, operator error, or compromised DOTS clients. of misconfiguration, operator error, or compromised DOTS clients.
DOTS servers attempting to honor conflicting requests may flap DOTS servers in the same administrative domain attempting to honor
network route or DNS information, degrading the networks conflicting requests may flap network route or DNS information,
attempting to participate in attack response with the DOTS degrading the networks attempting to participate in attack
clients. DOTS servers SHALL detect such conflicting requests, and response with the DOTS clients. DOTS servers in a single
administrative domain SHALL detect such conflicting requests, and
SHALL notify the DOTS clients in conflict. The notification SHALL notify the DOTS clients in conflict. The notification
SHOULD indicate the nature and scope of the conflict, for example, SHOULD indicate the nature and scope of the conflict, for example,
the overlapping prefix range in a conflicting mitigation request. the overlapping prefix range in a conflicting mitigation request.
SIG-010: Network Address Translator Traversal: DOTS clients may be SIG-010: Network Address Translator Traversal: DOTS clients may be
deployed behind a Network Address Translator (NAT), and need to deployed behind a Network Address Translator (NAT), and need to
communicate with DOTS servers through the NAT. DOTS protocols communicate with DOTS servers through the NAT. DOTS protocols
MUST therefore be capable of traversing NATs. MUST therefore be capable of traversing NATs.
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 [RFC5405] 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 packet
loss, the data channel is not expected to be constructed to deal with loss, the data channel is not expected to be constructed to deal with
attack conditions. As the primary function of the data channel is attack conditions. As the primary function of the data channel is
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Likewise, DOTS servers MUST refuse to allow creation, modification Likewise, DOTS servers MUST refuse to allow creation, modification
or deletion of scope aliases and black-/white-lists when the DOTS or deletion of scope aliases and black-/white-lists when the DOTS
client is unauthorized. client is unauthorized.
The modes of authorization are implementation-specific. The modes of authorization are implementation-specific.
2.5. Data Model Requirements 2.5. Data Model Requirements
The value of DOTS is in standardizing a mechanism to permit elements, The value of DOTS is in standardizing a mechanism to permit elements,
networks or domains under or under threat of DDoS attack to request networks or domains under threat of DDoS attack to request aid
aid mitigating the effects of any such attack. A well-structured mitigating the effects of any such attack. A well-structured DOTS
DOTS data model is therefore critical to the development of a data model is therefore critical to the development of a successful
successful DOTS protocol. DOTS protocol.
DM-001: Structure: The data model structure for the DOTS protocol DM-001: Structure: The data model structure for the DOTS protocol
may be described by a single module, or be divided into related may be described by a single module, or be divided into related
collections of hierarchical modules and sub-modules. If the data collections of hierarchical modules and sub-modules. If the data
model structure is split across modules, those distinct modules model structure is split across modules, those distinct modules
MUST allow references to describe the overall data model's MUST allow references to describe the overall data model's
structural dependencies. structural dependencies.
DM-002: Versioning: To ensure interoperability between DOTS protocol DM-002: Versioning: To ensure interoperability between DOTS protocol
implementations, data models MUST be versioned. The version implementations, data models MUST be versioned. The version
skipping to change at page 18, line 30 skipping to change at page 19, line 24
7.6. Initial revision 7.6. Initial revision
2015-09-24 Andrew Mortensen 2015-09-24 Andrew Mortensen
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, [RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768,
DOI 10.17487/RFC0768, August 1980, DOI 10.17487/RFC0768, August 1980,
<http://www.rfc-editor.org/info/rfc768>. <https://www.rfc-editor.org/info/rfc768>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981, DOI 10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>. <https://www.rfc-editor.org/info/rfc791>.
[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, [RFC0793] Postel, J., "Transmission Control Protocol", STD 7,
RFC 793, DOI 10.17487/RFC0793, September 1981, RFC 793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>. <https://www.rfc-editor.org/info/rfc793>.
[RFC1035] Mockapetris, P., "Domain names - implementation and [RFC1035] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, DOI 10.17487/RFC1035, specification", STD 13, RFC 1035, DOI 10.17487/RFC1035,
November 1987, <http://www.rfc-editor.org/info/rfc1035>. November 1987, <https://www.rfc-editor.org/info/rfc1035>.
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts - [RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122, Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989, DOI 10.17487/RFC1122, October 1989,
<http://www.rfc-editor.org/info/rfc1122>. <https://www.rfc-editor.org/info/rfc1122>.
[RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191, [RFC1191] Mogul, J. and S. Deering, "Path MTU discovery", RFC 1191,
DOI 10.17487/RFC1191, November 1990, DOI 10.17487/RFC1191, November 1990,
<http://www.rfc-editor.org/info/rfc1191>. <https://www.rfc-editor.org/info/rfc1191>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<http://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>. 2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation (CIDR): The Internet Address Assignment and Aggregation
Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August
2006, <http://www.rfc-editor.org/info/rfc4632>. 2006, <https://www.rfc-editor.org/info/rfc4632>.
[RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU
Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007,
<http://www.rfc-editor.org/info/rfc4821>. <https://www.rfc-editor.org/info/rfc4821>.
[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines [RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
for Application Designers", RFC 5405, for Application Designers", RFC 5405,
DOI 10.17487/RFC5405, November 2008, DOI 10.17487/RFC5405, November 2008,
<http://www.rfc-editor.org/info/rfc5405>. <https://www.rfc-editor.org/info/rfc5405>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6 [RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952, Address Text Representation", RFC 5952,
DOI 10.17487/RFC5952, August 2010, DOI 10.17487/RFC5952, August 2010,
<http://www.rfc-editor.org/info/rfc5952>. <https://www.rfc-editor.org/info/rfc5952>.
8.2. Informative References 8.2. Informative References
[I-D.ietf-dots-architecture] [I-D.ietf-dots-architecture]
Mortensen, A., Andreasen, F., Reddy, T., Mortensen, A., Andreasen, F., Reddy, T.,
christopher_gray3@cable.comcast.com, c., Compton, R., and christopher_gray3@cable.comcast.com, c., Compton, R., and
N. Teague, "Distributed-Denial-of-Service Open Threat N. Teague, "Distributed-Denial-of-Service Open Threat
Signaling (DOTS) Architecture", draft-ietf-dots- Signaling (DOTS) Architecture", draft-ietf-dots-
architecture-03 (work in progress), June 2017. architecture-04 (work in progress), July 2017.
[I-D.ietf-dots-use-cases] [I-D.ietf-dots-use-cases]
Dobbins, R., Fouant, S., Migault, D., Moskowitz, R., Dobbins, R., Migault, D., Fouant, S., Moskowitz, R.,
Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS
Open Threat Signaling (DDoS) Open Threat Signaling", Open Threat Signaling", draft-ietf-dots-use-cases-07 (work
draft-ietf-dots-use-cases-05 (work in progress), May 2017. in progress), July 2017.
[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston, [RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E. A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261, Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002, DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>. <https://www.rfc-editor.org/info/rfc3261>.
[RFC7092] Kaplan, H. and V. Pascual, "A Taxonomy of Session
Initiation Protocol (SIP) Back-to-Back User Agents",
RFC 7092, DOI 10.17487/RFC7092, December 2013,
<https://www.rfc-editor.org/info/rfc7092>.
[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet [RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
Denial-of-Service Considerations", RFC 4732, Denial-of-Service Considerations", RFC 4732,
DOI 10.17487/RFC4732, December 2006, DOI 10.17487/RFC4732, December 2006,
<http://www.rfc-editor.org/info/rfc4732>. <https://www.rfc-editor.org/info/rfc4732>.
Authors' Addresses Authors' Addresses
Andrew Mortensen Andrew Mortensen
Arbor Networks Arbor Networks
2727 S. State St 2727 S. State St
Ann Arbor, MI 48104 Ann Arbor, MI 48104
United States United States
Email: amortensen@arbor.net Email: amortensen@arbor.net
Robert Moskowitz Robert Moskowitz
HTT Consulting Huawei
Oak Park, MI 42837 Oak Park, MI 42837
United States United States
Email: rgm@htt-consult.com Email: rgm@htt-consult.com
Tirumaleswar Reddy Tirumaleswar Reddy
McAfee, Inc. McAfee, Inc.
Embassy Golf Link Business Park Embassy Golf Link Business Park
Bangalore, Karnataka 560071 Bangalore, Karnataka 560071
India India
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