draft-ietf-dots-requirements-08.txt   draft-ietf-dots-requirements-09.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 8, 2018 Huawei Expires: June 22, 2018 Huawei
T. Reddy T. Reddy
McAfee, Inc. McAfee, Inc.
December 05, 2017 December 19, 2017
Distributed Denial of Service (DDoS) Open Threat Signaling Requirements Distributed Denial of Service (DDoS) Open Threat Signaling Requirements
draft-ietf-dots-requirements-08 draft-ietf-dots-requirements-09
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 8, 2018. This Internet-Draft will expire on June 22, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these 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
described in the Simplified BSD License. described in the Simplified BSD License.
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 . . . . . . . . . . . . . . . . 12 2.3. Data Channel Requirements . . . . . . . . . . . . . . . . 12
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 . . . . . . . . . . . . . . . . . 18
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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
flows. The filter will typically have a policy associated with flows. The filter will typically have a policy associated with
it, e.g., rate-limiting or discarding matching traffic. it, e.g., rate-limiting or discarding matching traffic [RFC4949].
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
indicating sources from which traffic should always be allowed, indicating sources from which traffic should always be allowed,
regardless of contradictory data gleaned in a detected attack. regardless of contradictory data gleaned in a detected 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 protocols.
DOTS is an advisory protocol. An active DDoS attack against the The DOTS protocols enable and manage mitigation on behalf of a
entity controlling the DOTS client need not be present before network domain or resource which is or may become the focus of a DDoS
establishing a communication channel between DOTS agents. Indeed, attack. An active DDoS attack against the entity controlling the
establishing a relationship with peer DOTS agents during normal DOTS client need not be present before establishing a communication
network conditions provides the foundation for more rapid attack channel between DOTS agents. Indeed, establishing a relationship
response against future attacks, as all interactions setting up DOTS, with peer DOTS agents during normal network conditions provides the
including any business or service level agreements, are already foundation for more rapid attack response against future attacks, as
complete. Peer DOTS agents are provisioned to a DOTS client using a all interactions setting up DOTS, including any business or service
variety of manual or dynamic methods. level agreements, are already complete. Reachability information of
peer DOTS agents is 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. Multi-homed DOTS clients must be local to the DOTS clients' domain. Multi-homed DOTS clients must be
able to select the appropriate DOTS server(s) to which a mitigation able to select the appropriate DOTS server(s) to which a mitigation
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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 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 the 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 listen 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
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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 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 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;
exchange of incident reports; and other hinting or configuration exchange of incident reports; and other hinting or configuration
supplementing attack response. supplementing attack response.
As the resilience requirements for the DOTS signal channel mandate As the resilience requirements for the DOTS signal channel mandate
small signal message size, a separate, secure data channel small signal message size, a separate, secure data channel
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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.
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 timeout period has elapsed. Because after a mutually agreed upon retransmission procedure has been
heartbeat loss is much more likely during volumetric attack, DOTS exhausted. Because heartbeat loss is much more likely during
agents SHOULD avoid signal channel termination when mitigation is volumetric attack, DOTS agents SHOULD avoid signal channel
active and heartbeats are not received by either DOTS agent for an termination when mitigation is active and heartbeats are not
extended period. In such circumstances, DOTS clients MAY attempt received by either DOTS agent for an extended period. In such
to reestablish the signal channel. DOTS servers SHOULD monitor circumstances, DOTS clients MAY attempt to reestablish the signal
the attack, using feedback from the mitigator and other available channel, but SHOULD continue to send heartbeats so that the DOTS
sources, and MAY use the absence of attack traffic and lack of server knows the session is still partially alive. DOTS servers
client heartbeats as an indication the signal channel is defunct. 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.
Due to the increased likelihood of packet loss caused by link Due to the increased likelihood of packet loss caused by link
congestion during an attack, DOTS servers SHOULD NOT redirect congestion during an attack, DOTS servers SHOULD NOT redirect
while mitigation is enabled during an active attack against a while mitigation is enabled during an active attack against a
target in the DOTS client's domain. target in the DOTS client's domain.
SIG-005 Mitigation Requests and Status: Authorized DOTS clients MUST SIG-005 Mitigation Requests and Status: Authorized DOTS clients MUST
be able to request scoped mitigation from DOTS servers. DOTS be able to request scoped mitigation from DOTS servers. DOTS
servers MUST send mitigation request status in response to DOTS servers MUST send mitigation request status in response to granted
clients requests for mitigation, and SHOULD accept scoped DOTS clients requests for mitigation. If a DOTS server rejects an
mitigation requests from authorized DOTS clients. DOTS servers authorized request for mitigation, the DOTS server MUST include a
MAY reject authorized requests for mitigation, but MUST include a
reason for the rejection in the status message sent to the client. reason for the rejection in the status message sent to the client.
Due to the higher likelihood of packet loss during a DDoS attack, Due to the higher likelihood of packet loss during a DDoS attack,
DOTS servers SHOULD regularly send mitigation status to authorized DOTS servers SHOULD regularly send mitigation status to authorized
DOTS clients which have requested and been granted mitigation, DOTS clients which have requested and been granted mitigation,
regardless of client requests for mitigation status. regardless of client requests for mitigation status.
When DOTS client-requested mitigation is active, DOTS server When DOTS client-requested mitigation is active, DOTS server
status messages SHOULD include the following mitigation metrics: status messages SHOULD include the following mitigation metrics:
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When DOTS client-requested mitigation is active, DOTS server When DOTS client-requested mitigation is active, DOTS server
status messages SHOULD include the following mitigation metrics: status messages SHOULD include the following mitigation metrics:
* Total number of packets blocked by the mitigation * Total number of packets blocked by the mitigation
* Current number of packets per second blocked * Current number of packets per second blocked
* Total number of bytes blocked * Total number of bytes blocked
* Current number of bytes per second blocked * Current number of bytes per second blocked
DOTS clients MAY take these metrics into account when determining DOTS clients MAY take these metrics into account when determining
whether to ask the DOTS server to cease mitigation. whether to ask the DOTS server to cease mitigation.
Once a DOTS client requests mitigation, the client MAY withdraw A DOTS client MAY withdraw a mitigation request at any time,
that request at any time, regardless of whether mitigation is regardless of whether mitigation is currently active. The DOTS
currently active. The DOTS server MUST immediately acknowledge a server MUST immediately acknowledge a DOTS client's request to
DOTS client's request to stop mitigation. 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 initial active-but-terminating period is implementation- The initial active-but-terminating period is implementation- and
specific, but SHOULD be sufficiently long to absorb latency deployment- specific, but SHOULD be sufficiently long to absorb
incurred by route propagation. If the client requests mitigation latency incurred by route propagation. If the client requests
again before the initial active-but-terminating period elapses, mitigation again before the initial active-but-terminating period
the DOTS server MAY exponentially increase the active-but- elapses, the DOTS server MAY exponentially increase the active-
terminating period up to a maximum of 300 seconds (5 minutes). 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
clients to extend mitigation as necessary for the duration of an clients to extend mitigation as necessary for the duration of an
attack. attack.
DOTS servers MUST treat a mitigation terminated due to lifetime DOTS servers MUST treat a mitigation terminated due to lifetime
expiration exactly as if the DOTS client originating the expiration exactly as if the DOTS client originating the
mitigation had asked to end the mitigation, including the active- mitigation had asked to end the mitigation, including the active-
but-terminating period, as described above in SIG-005. but-terminating period, as described above in SIG-005.
DOTS clients SHOULD include a mitigation lifetime in all DOTS clients MUST include a mitigation lifetime in all mitigation
mitigation requests. If a DOTS client does not include a requests.
mitigation lifetime in requests for help sent to the DOTS server,
the DOTS server will use a reasonable default as defined by the
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 clients MUST be prepared to not be requesting protection. DOTS clients MUST be prepared to not be
granted mitigations with indefinite lifetimes. DOTS servers MAY granted mitigations with indefinite lifetimes. DOTS servers MAY
refuse mitigations with indefinite lifetimes, for policy reasons. refuse mitigations with indefinite lifetimes, for policy reasons.
The reasons themselves are out of scope. If the DOTS server does The reasons themselves are out of scope. If the DOTS server does
not grant a mitigation request with an indefinite mitigation not grant a mitigation request with an indefinite mitigation
lifetime, it MUST set the lifetime to a value that is configured lifetime, it MUST set the lifetime to a value that is configured
locally. That value MUST be returned in a reply to the requesting locally. That value MUST be returned in a reply to the requesting
DOTS client. 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 prefixes in CIDR notation [RFC4632] * IPv4 prefixes in CIDR notation [RFC4632]
* IPv6 addresses [RFC4291][RFC5952]
* 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
name resolution is managed on the DOTS 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
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 mitigation requests. DOTS clients MAY also include
attack details. Such supplemental information is OPTIONAL, and additional attack details. DOTS servers MAY ignore such
DOTS servers MAY ignore it when enabling countermeasures on the supplemental information when enabling countermeasures on the
mitigator. mitigator.
As an active attack evolves, clients MUST be able to adjust as As an active attack evolves, DOTS clients MUST be able to adjust
necessary the scope of requested mitigation by refining the scope as necessary the scope of requested mitigation by refining the
of resources requiring mitigation. scope of resources requiring mitigation.
The DOTS client may obtain the mitigation scope through direct A DOTS client may obtain the mitigation scope through direct
provisioning or through implementation-specific methods of provisioning or through implementation-specific methods of
discovery. DOTS clients MUST support at least one mechanism to discovery. DOTS clients MUST support at least one mechanism to
obtain mitigiation scope. obtain mitigation scope.
SIG-008 Mitigation Efficacy: When a mitigation request by a DOTS SIG-008 Mitigation Efficacy: When a mitigation request is active,
client is active, DOTS clients SHOULD transmit a metric of DOTS clients SHOULD transmit a metric of perceived mitigation
perceived mitigation efficacy to the DOTS server. DOTS servers efficacy to the DOTS server. DOTS servers MAY use the efficacy
MAY use the efficacy metric to adjust countermeasures activated on metric to adjust countermeasures activated on a mitigator on
a mitigator on behalf of a DOTS client. 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 pools 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 in the same administrative domain attempting to honor DOTS servers in the same administrative domain attempting to honor
conflicting requests may flap network route or DNS information, conflicting requests may flap network route or DNS information,
degrading the networks attempting to participate in attack degrading the networks attempting to participate in attack
response with the DOTS clients. DOTS servers in a single response with the DOTS clients. DOTS servers in a single
administrative domain SHALL detect such conflicting requests, and administrative domain SHALL detect such conflicting requests, and
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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
data exchange, a reliable transport is required in order for DOTS data exchange, a reliable transport is required in order for DOTS
agents to detect data delivery success or failure. agents to detect data delivery success or failure.
The data channel must be extensible. We anticipate the data channel The DOTS data channel protocol MUST be extensible. We anticipate the
will be used for such purposes as configuration or resource data channel will be used for such purposes as configuration or
discovery. For example, a DOTS client may submit to the DOTS server resource discovery. For example, a DOTS client may submit to a DOTS
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
sensitive content sent between DOTS agents requires extra precautions sensitive content sent between DOTS agents requires extra precautions
to ensure data privacy and authenticity. to ensure data privacy and authenticity.
DATA-001 Reliable transport: Messages sent over the data channel DATA-001 Reliable transport: Messages sent over the data channel
MUST be delivered reliably, in order sent. MUST be delivered reliably, in order sent.
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information leaks or malicious transactions on behalf of the information leaks or malicious transactions on behalf of the
sending agent (see Section 4 below). Consequently data sent over sending agent (see Section 4 below). Consequently data sent over
the data channel MUST be encrypted and authenticated using current the data channel MUST be encrypted and authenticated using current
industry best practices. DOTS servers MUST enable means to industry best practices. DOTS servers MUST enable means to
prevent leaking operationally or privacy-sensitive data. Although prevent leaking operationally or privacy-sensitive data. Although
administrative entities participating in DOTS may detail what data administrative entities participating in DOTS may detail what data
may be revealed to third-party DOTS agents, such considerations may be revealed to third-party DOTS agents, such considerations
are not in scope for this document. are not in scope for this document.
DATA-003 Resource Configuration: To help meet the general and signal DATA-003 Resource Configuration: To help meet the general and signal
channel requirements in this document, DOTS server implementations channel requirements in Section 2.2, DOTS server implementations
MUST provide an interface to configure resource identifiers, as MUST provide an interface to configure resource identifiers, as
described in SIG-007. DOTS server implementations MAY expose described in SIG-007. DOTS server implementations MAY expose
additional configurability. Additional configurability is additional configurability. Additional configurability is
implementation-specific. implementation-specific.
DATA-004 Black- and whitelist management: DOTS servers MUST provide DATA-004 Black- and whitelist management: DOTS servers MUST provide
methods for DOTS clients to manage black- and white-lists of methods for DOTS clients to manage black- and white-lists of
traffic destined for resources belonging to a client. traffic destined for resources belonging to a client.
For example, a DOTS client should be able to create a black- or For example, a DOTS client should be able to create a black- or
whitelist entry; retrieve a list of current entries from either whitelist entry, retrieve a list of current entries from either
list; update the content of either list; and delete entries as list, update the content of either list, and delete entries as
necessary. necessary.
How the DOTS server authorizes DOTS client management of black- How a DOTS server authorizes DOTS client management of black- and
and white-list entries is implementation-specific. white-list entries is implementation-specific.
2.4. Security requirements 2.4. Security Requirements
DOTS must operate within a particularly strict security context, as DOTS must operate within a particularly strict security context, as
an insufficiently protected signal or data channel may be subject to an insufficiently protected signal or data channel may be subject to
abuse, enabling or supplementing the very attacks DOTS purports to abuse, enabling or supplementing the very attacks DOTS purports to
mitigate. mitigate.
SEC-001 Peer Mutual Authentication: DOTS agents MUST authenticate SEC-001 Peer Mutual Authentication: DOTS agents MUST authenticate
each other before a DOTS signal or data channel is considered each other before a DOTS signal or data channel is considered
valid. The method of authentication is not specified, but should valid. The method of authentication is not specified, but should
follow current industry best practices with respect to any follow current industry best practices with respect to any
skipping to change at page 15, line 10 skipping to change at page 15, line 12
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 threat of DDoS attack to request aid networks or domains under threat of DDoS attack to request aid
mitigating the effects of any such attack. A well-structured DOTS mitigating the effects of any such attack. A well-structured DOTS
data model is therefore critical to the development of a successful data model is therefore critical to the development of successful
DOTS protocol. DOTS protocols.
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. How the protocols
number of the initial data model SHALL be 1. Each published represent data model versions is not defined in this document.
change to the initial published DOTS data model SHALL increment
the data model version by 1.
How the protocol represents data model versions is not defined in
this document.
DM-003: Mitigation Status Representation: The data model MUST DM-003: Mitigation Status Representation: The data model MUST
provide the ability to represent a request for mitigation and the provide the ability to represent a request for mitigation and the
withdrawal of such a request. The data model MUST also support a withdrawal of such a request. The data model MUST also support a
representation of currently requested mitigation status, including representation of currently requested mitigation status, including
failures and their causes. failures and their causes.
DM-004: Mitigation Scope Representation: The data model MUST support DM-004: Mitigation Scope Representation: The data model MUST support
representation of a requested mitigation's scope. As mitigation representation of a requested mitigation's scope. As mitigation
scope may be represented in several different ways, per SIG-007 scope may be represented in several different ways, per SIG-007
skipping to change at page 19, line 34 skipping to change at page 19, line 34
[RFC7092] Kaplan, H. and V. Pascual, "A Taxonomy of Session [RFC7092] Kaplan, H. and V. Pascual, "A Taxonomy of Session
Initiation Protocol (SIP) Back-to-Back User Agents", Initiation Protocol (SIP) Back-to-Back User Agents",
RFC 7092, DOI 10.17487/RFC7092, December 2013, RFC 7092, DOI 10.17487/RFC7092, December 2013,
<https://www.rfc-editor.org/info/rfc7092>. <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,
<https://www.rfc-editor.org/info/rfc4732>. <https://www.rfc-editor.org/info/rfc4732>.
[RFC4949] Shirey, R., "Internet Security Glossary, Version 2",
FYI 36, RFC 4949, DOI 10.17487/RFC4949, August 2007,
<https://www.rfc-editor.org/info/rfc4949>.
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
Huawei 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
Email: TirumaleswarReddy_Konda@McAfee.com Email: TirumaleswarReddy_Konda@McAfee.com
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