wdiff draft-ietf-dots-requirements-00.txt draft-ietf-dots-requirements-01.txt

DOTS A. Mortensen
Internet-Draft Arbor Networks, Inc.
Intended status: Informational R. Moskowitz
Expires: April 21, September 19, 2016 HTT Consulting
T. Reddy
Cisco Systems, Inc.
October 19, 2015

DDoS
March 18, 2016

Distributed Denial of Service (DDoS) Open Threat Signaling Requirements
draft-ietf-dots-requirements-00
draft-ietf-dots-requirements-01

Abstract

This document defines the requirements for the DDoS Distributed Denial of
Service (DDoS) Open Threat Signaling (DOTS) protocols coordinating
attack response against
Distributed Denial of Service (DDoS) DDoS attacks.

Status of This Memo

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provisions of BCP 78 and BCP 79.

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This Internet-Draft will expire on April 21, September 19, 2016.

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Table of Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Overview . . . . . . . Context and Motivation . . . . . . . . . . . . . . . . . 2
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements . . . . . . . . . . . . . . . . . . . . . . . . 5
2.1. General Requirements . . . . . . . . . . . . . . . . . . 6
2.2. Operational requirements Requirements . . . . . . . . . . . . . . . . 7
2.3. Data channel requirements Channel Requirements . . . . . . . . . . . . . . . . 9 10
2.4. Data model Security requirements . . . . . . . . . . . . . . . . . 10 . 11
3. Congestion Control Considerations . . . . . . . . . . . . . . 10 12
4. Security Considerations . . . . . . . . . . . . . . . . . . . 10 12
5. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 12
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.1. 13
7.1. 01 revision . . . . . . . . . . . . . . . . . . . . . . . 13
7.2. 00 revision . . . . . . . . . . . . . . . . . . . . . . . 11
5.2. 13
7.3. Initial revision . . . . . . . . . . . . . . . . . . . . 11
6. 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 11
6.1. 14
8.1. Normative References . . . . . . . . . . . . . . . . . . 11
6.2. 14
8.2. Informative References . . . . . . . . . . . . . . . . . 11 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 15

1. Introduction

1.1. Overview Context and Motivation

Distributed Denial of Service (DDoS) attacks continue to plague
networks around the globe, from Tier-1 service providers on down to
enterprises and small businesses. Attack scale and frequency
similarly have continued to increase, thanks to in part as a result of software
vulnerabilities leading to reflection and amplification attacks.
Once staggering attack traffic volume is now the norm, and the impact
of larger-scale attacks attract the attention of international press
agencies.

The higher profile and greater impact of contemporary DDoS attacks has led to increased
focus on coordinated attack response. Many institutions and
enterprises lack the resources or expertise to operate on-premise
attack prevention solutions themselves, or simply find themselves
constrained by local bandwidth limitations. To address such gaps,
security service providers have begun to offer on-
demand on-demand traffic
scrubbing services. Each service offers its own interface for
subscribers to request attack mitigation, tying subscribers to
proprietary implementations while also limiting the subset of network
elements capable of participating in the attack response. As a
result of incompatibility across services, attack
response responses may be
fragmentary or otherwise incomplete, leaving key players in the
attack path unable to assist in the defense.

There are many ways to respond to an ongoing DDoS attack, some of
them better than others, but the

The lack of a common method to coordinate a real-time response across layers among
involved actors and network domains inhibits the speed and
effectiveness of DDoS attack mitigation. This document describes the
required characteristics of DOTS was formed protocols that would mitigate
contemporary DDoS attack impact and lead to address this lack. The more efficient defensive
strategies.

DOTS protocols are
therefore not is less concerned with the form of response, but rather defensive action than with
communicating the need for a response, supplementing the call that action. DOTS supplements calls for
help with pertinent details about the detected attack. To achieve
this aim, the protocol must permit the attack, allowing
entities participating in DOTS client to request or
withdraw a request for coordinated mitigation; to set the scope of
mitigation, restricted to the client's network space; and to supply
summarized attack information and additional hints form ad hoc, adaptive alliances
against DDoS attacks as described in the DOTS server
elements can use to increase the accuracy and speed of the attack
response. cases
[I-D.ietf-dots-use-cases]. The protocol must also continue to operate even in extreme network
conditions. It must be resilient enough to ensure a high probability
of signal delivery in spite of high packet loss rates. As such,
elements should be requirements in regular, bidirectional contact to measure peer
health, provide mitigation-related feedback, and allow for active
mitigation adjustments.

Lastly, the protocol must take care to ensure the confidentiality,
integrity and authenticity of messages passed between peers to
prevent the protocol from being repurposed to contribute to the very
attacks it's meant to deflect.

Drawing on the DOTS use cases [I-D.ietf-dots-use-cases] for
reference, this document details the requirements for protocols
achieving the DOTS goal of standards-based open threat signaling. are
derived from those use cases.

1.2. Terminology

The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].

The

This document adopts the following terms terms:

DDoS: A distributed denial-of-service attack, in which of traffic
originating from multiple sources are used directed at a target on a
network. DDoS attacks are intended to define relationships between
elements, cause a negative impact on
the data they exchange, and methods availability of communication among
them: servers, services, applications, and/or other
functionality of an attack target. Denial-of-service
considerations are discussed in detail in [RFC4732].

DDoS attack target: A networked server, network service or
application that is the focus of a DDoS attack.

DDoS attack telemetry: collected Collected network traffic characteristics
defining the nature of a DDoS attack.

mitigation: This document makes no
assumptions regarding telemetry collection methodology.

Countermeasure: An action or set of actions taken to recognize and
filter out DDoS attack traffic while passing legitimate traffic to
the attack target.

Mitigation: A defensive response set of countermeasures enforced against traffic
destined for the target or targets of a detected or reported DDoS
attack,
performed where countermeasure enforcement is managed by an entity
in the network path between attack sources and the attack target, either through inline deployment or some
form of traffic diversion. The form mitigation takes target.
Mitigation methodology is out of scope for this document.

mitigator: A

Mitigator: An entity, typically a network element element, capable of
performing mitigation of a detected or reported DDoS attack. For
the purposes of this document, this entity is a black box capable
of mitigation, making no assumptions about availability or design
of countermeasures, nor about the programmable interface between
this entity and other network elements. The mitigator and DOTS
server are assumed to belong to the same administrative entity.

DOTS client: A DOTS-aware network element software module responsible for requesting
attack response coordination with another other DOTS-aware element, with the expectation
that the remote element is capable of helping fend off the attack
against the client. elements.

DOTS server: A DOTS-aware network element software module handling and responding to
messages from a DOTS client. clients. The DOTS server MAY enable mitigation
on behalf of the DOTS client, if requested, by communicating the
DOTS client's request to the mitigator and relaying any mitigator
feedback to the requesting DOTS client. A DOTS server may also be
a mitigator.

DOTS relay: A DOTS-aware network element software module positioned between a DOTS
server and a DOTS client. A DOTS client in the signaling path. A DOTS relay
receives messages from a DOTS client and relays them to a DOTS
server, and similarly passes messages from the DOTS server to the
DOTS client. A DOTS relay acts as a proxy or bridge between
stateful and stateless transport signaling, and may also aggregate
signaling from multiple downstream DOTS clients into a single
session with an upstream DOTS server or DOTS relay.

DOTS agents: A collective term for Any DOTS functional element, including DOTS clients,
DOTS servers and DOTS relays.

signal

Signal channel: A bidirectional, mutually authenticated
communication layer between DOTS agents characterized by
resilience even in conditions leading to severe packet loss, such
as a volumetric DDoS attack causing network congestion.

DOTS signal: A concise authenticated status/control message
transmitted between DOTS agents, used to indicate client's need
for mitigation, as well as to convey the status of any requested
mitigation.

heartbeat:

Heartbeat: A keep-alive message transmitted between DOTS agents over the signal
channel, used as a keep-alive and to measure peer health. Heartbeat
functionality is not required to be distinct from signal.

client

Client signal: A message sent from a DOTS client to a DOTS server or
DOTS relay over the signal channel, possibly traversing a DOTS relay, indicating the DOTS client's
need for mitigation, as well as the scope of any requested
mitigation, optionally including detected additional attack telemetry details to
supplement server-initiated mitigation.

server

Server signal: A message sent from a DOTS server to a DOTS client or
DOTS relay 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 the DOTS client, clients with which the server has
established signaling sessions, containing information about the
status of any requested DOTS client-requested mitigation and its efficacy.

data

Data channel: A secure communication layer between client DOTS clients and server
DOTS servers used for infrequent bulk exchange of data not easily
or appropriately communicated through the signal channel under
attack conditions.

blacklist: a

Blacklist: A list of source addresses or addresses, prefixes and/or other identifiers
indicating sources from which traffic should be blocked.

whitelist: a blocked,
regardless of traffic content.

Whitelist: A list of source addresses or addresses, prefixes and/or other
identifiersfrom indicating sources from which traffic should
always be allowed, regardless of contradictory data gleaned in a
detected attack.

Multi-homed DOTS client: A DOTS client exchanging messages with
multiple DOTS servers, each in a separate administrative domain.

2. Requirements

This section describes the required features and characteristics of
the DOTS protocols. The requirements are informed by

DOTS is an advisory protocol. An active DDoS attack against the use cases
described in [I-D.ietf-dots-use-cases].
entity controlling the DOTS client need not be present before
establishing DOTS communication between DOTS agents. Indeed,
establishing a relationship with peer DOTS agents during nominal
network conditions provides the foundation for more rapid attack
response against future attacks, as all interactions setting up DOTS,
including any business or service level agreements, are already
complete.

DOTS must at a minimum make it possible for a DOTS client to request
a DOTS server's aid in mounting a coordinated defense against a
detected attack, by signaling inter- or intra-domain using the DOTS
protocol. as requested by
local operators. DOTS clients should similarly be able to withdraw
aid requests. DOTS requires no justification from DOTS clients for
requests arbitrarily. for help, nor must DOTS clients justify withdrawing help
requests: the decision is local to the entity owning the DOTS
clients. Regular feedback between DOTS client clients and DOTS server
supplement the defensive alliance by maintaining a common
understanding of DOTS peer health and activity. Bidirectional
communication between DOTS client clients and server DOTS servers is therefore
critical.

Yet the DOTS protocol must also work with a set of competing operational goals.
On the one hand, the protocol must be resilient under extremely
hostile network conditions, providing continued contact between DOTS
agents even as attack traffic saturates the link. Such resiliency
may be developed several ways, but characteristics such as small
message size, asynchronous, redundant message delivery and minimal
connection overhead (when possible given local network policy) with a given network will
tend to contribute to the robustness demanded by a viable DOTS
protocol. Operators of peer DOTS-enabled domains may enable quality-
or class-of-service traffic tagging to increase the probability of
successful DOTS signal delivery, but DOTS requires no such policies
be in place. The DOTS solution indeed must be viable especially in
their absence.

On the other hand, DOTS must have adequate include protections ensuring message
confidentiality, integrity and authenticity to keep the protocol from
becoming another vector for the very attacks it's meant to help fight
off. The DOTS
client clients must be authenticated able to the authenticate DOTS server, servers, and
vice versa, for DOTS to operate safely, meaning the DOTS agents must
have a way to negotiate and agree upon the terms of protocol
security. Attacks against the transport protocol should not offer a
means of attack against the message confidentiality, integrity and
authenticity.

The DOTS server and client must also have some common method of
defining the scope of any mitigation performed by the mitigator, as
well as making adjustments to other commonly configurable features,
such as listen ports, exchanging black- and white-lists, and so on.

Finally, DOTS should provide sufficient extensibility to meet local,
vendor or future needs in coordinated attack defense, although this
consideration is necessarily superseded by the other operational
requirements.

2.1. General Requirements

G-001 Interoperability: DOTS's objective is to develop a standard
mechanism for signaling detected ongoing DDoS attacks. That
objective is unattainable without well-defined specifications for
any protocols or data models emerging from DOTS. All protocols,
data models and interfaces MUST be detailed enough to ensure
interoperable implementations.

G-002

GEN-001 Extensibility: Any protocols or Protocols and data models developed as part
of DOTS MUST be designed extensible in order to support future extensions. Provided
they do not undermine the interoperability and backward
compatibility requirements, extensions are a critical part of
keeping keep DOTS adaptable to changing
operational and proprietary
needs to keep pace with evolving DDoS attack methods.

G-003 Resilience: defenses. Future extensions MUST
be backward compatible.

GEN-002 Resilience and Robustness: The signaling protocol MUST be
designed to maximize the probability of signal delivery even under
the severely constrained network conditions imposed by the particular
attack traffic. The protocol SHOULD MUST be resilient, that is, continue
operating despite message loss and out-of-order or redundant
signal delivery.

G-004

GEN-003 Bidirectionality: To support peer health detection, to
maintain an open signal channel, and to increase the probability
of signal delivery during attack, the signal channel MUST be
bidirectional, with client and server transmitting signals to each
other at regular intervals, regardless of any client request for
mitigation.

G-005 Unidirectional messages MUST be supported within the
bidirectional signal channel to allow for unsolicited message
delivery, enabling asynchronous notifications between agents.

GEN-004 Sub-MTU Message Size: To avoid message fragmentation and the
consequently decreased probability of message delivery, signaling
protocol message size MUST be kept under signaling path Maximum
Transmission Unit (MTU), including the byte overhead of any
encapsulation, transport headers, and transport- or message-level
security.

G-006 Message Integrity: DOTS protocols MUST take steps to protect
the confidentiality, integrity and authenticity of messages sent
between client and server. While specific transport- and message-
level security options are not specified, the protocols MUST
follow current industry best practices for encryption and message
authentication.

In order for DOTS protocols to remain secure despite advancements
in cryptanalysis, DOTS agents MUST be able to negotiate the terms
and mechanisms of protocol security, subject to the
interoperability and signal message size requirements above.

G-007 Message Replay Protection: In order to prevent a passive
attacker from capturing and replaying old messages, DOTS protocols
MUST provide a method for replay detection, such as including a
timestamp or sequence number in every heartbeat and signal sent
between DOTS agents.

G-008

GEN-005 Bulk Data Exchange: Infrequent bulk data exchange between
DOTS
client and server agents can also significantly augment attack response
coordination, permitting such tasks as population of black- or
white-listed source addresses; address or prefix group aliasing;
exchange of incident reports; and other hinting or configuration
supplementing attack response.

As the resilience requirements for the DOTS signal channel mandate
small signal message size, a separate, secure data channel
utilizing an established reliable transport protocol SHOULD MUST be used
for bulk data exchange. The mechanism for bulk data exchange is not yet
specified, but the nature of the data involved suggests use of a
reliable, adaptable protocol with established and configurable
conventions for authentication and authorization.

2.2. Operational requirements Requirements

OP-001 Use of Common Transports: Transport Protocols: DOTS MUST operate over
common widely deployed and standardized transport protocols.
While the protocol resilience
requirement strongly RECOMMENDS the use of connectionless
protocols, in particular the User Datagram Protocol (UDP)
[RFC0768], use of a standardized, connection-oriented protocol
like [RFC0768] SHOULD be used
for the signal channel, the Transmission Control Protocol (TCP)
[RFC0793] MAY be used if necessary due to network policy or middleware limitations.

OP-002 Peer Mutual Authentication:
middlebox capabilities or configurations. The client and server data channel MUST
authenticate each other before a DOTS session is considered
active. The method of authentication is not specified, but should
follow current industry best practices with respect to any
cryptographic mechanisms to authenticate the remote peer.

OP-003
use TCP; see Section 2.3 below.

OP-002 Session Health Monitoring: The client and server Peer DOTS agents MUST regularly
send heartbeats to each other after mutual authentication in order
to keep the DOTS session open. A session MUST be considered
active until a client or server DOTS agent explicitly ends the session, or either
DOTS agent fails to receive heartbeats from the other after a
mutually negotiated timeout period has elapsed.

OP-004 Mitigation Capability Opacity:

OP-003 Session Redirection: In order to increase DOTS is a threat signaling
protocol. The server operational
flexibility and mitigator MUST NOT make scalability, DOTS servers SHOULD be able to
redirect DOTS clients to another DOTS server or relay at any assumption
about time.
Due to the attack detection, classification, or mitigation
capabilities decreased probability of the client. While the DOTS server and mitigator MAY
take hints from any signal delivery
due to link congestion, it is RECOMMENDED DOTS servers avoid
redirecting while mitigation is enabled during an active attack telemetry included
against a target in client signals, the server and mitigator cannot depend on DOTS client's domain. Either the client for
authoritative attack classification. Similarly, DOTS
servers have to fate-share the mitigator
cannot assume security state, the client can or will mitigate attack traffic on
its own.

The client likewise MUST NOT make any assumptions about the
capabilities of the server or mitigator
have separate security state with respect each potential redirectable
server, or be able to detection,
classification, and mitigation of DDoS attacks. The form negotiate new state as part of any
attack response undertaken by the mitigator is not in scope.

OP-005 redirection.

OP-004 Mitigation Status: DOTS MUST provide a means to report the
status of an action requested by a DOTS client. In particular,
DOTS clients MUST be able to request or withdraw a request for
mitigation from the DOTS server. The DOTS server MUST acknowledge
a DOTS client's request to withdraw from coordinated attack
response in subsequent signals, and MUST cease mitigation activity
as quickly as possible. However, a DOTS client rapidly toggling
active mitigation may result in undesirable side-effects for the
network path, such as route or DNS [RFC1034] flapping. A DOTS
server therefore MAY continue mitigating for a mutually negotiated
period after receiving the DOTS client's request to stop.

A server MAY refuse to engage in coordinated attack response with
a client. To make the status of a client's request clear, the
server MUST indicate in server signals whether client-initiated
mitigation is active. When a client-initiated mitigation is
active, and threat handling details such as mitigation scope and
statistics are available to the server, the server SHOULD include
those details in server signals sent to the client. DOTS clients
SHOULD take mitigation statistics into account when deciding
whether to request the DOTS server cease mitigation.

OP-006

OP-005 Mitigation Scope: Lifetime: A DOTS clients MUST client SHOULD indicate the
desired
address space coverage lifetime of any mitigation, for example by using
Classless Internet Domain Routing (CIDR) [RFC1518],[RFC1519]
prefixes, [RFC2373] for IPv6 prefixes, the length/prefix
convention established in mitigation requested from the DOTS server.
As DDoS attack duration is unpredictable, the DOTS client SHOULD
be able to extend mitigation lifetime with periodic renewed
requests for help. When the mitigation lifetime comes to an end,
the DOTS server SHOULD delay session termination for a protocol-
defined grace period to allow for delivery of delayed mitigation
renewals over the signal channel. After the grace period elapses,
the DOTS server MAY terminate the session at any time.

If a DOTS client does not include a mitigation lifetime in
requests for help sent to the DOTS server, the DOTS server will
use a reasonable default as defined by the protocol. As above,
the DOTS client MAY extend a current mitigation request's lifetime
trivially with renewed requests for help.

A DOTS client MAY also request an indefinite mitigation lifetime,
enabling architectures in which the mitigator is always in the
traffic path to the resources for which the DOTS client is
requesting protection. DOTS servers MAY refuse such requests for
any reason. The reasons themselves are not in scope.

OP-006 Mitigation Scope: DOTS clients MUST indicate the desired
address or prefix space coverage of any mitigation, for example by
using Classless Internet Domain Routing (CIDR) [RFC1518],[RFC1519]
prefixes, [RFC2373] for IPv6 [RFC2460] prefixes, the length/prefix
convention established in the Border Gateway Protocol (BGP)
[RFC4271], SIP URIs [RFC3261], E.164 numbers, DNS names, or by a
prefix group alias agreed upon with the server through the data
channel.

If there is additional information available narrowing the scope
of any requested attack response, such as targeted port range,
protocol, or service, DOTS clients SHOULD include that information
in client signals. DOTS clients MAY also include additional
attack details. Such supplemental information is OPTIONAL, and
DOTS servers MAY ignore it when enabling countermeasures on the
mitigator.

As an active attack evolves, clients MUST be able to adjust as
necessary the scope of requested mitigation by refining the
address space requiring intervention.

OP-007 Mitigation Efficacy: When a mitigation request by a DOTS
client is active, DOTS clients SHOULD transmit a metric of
perceived mitigation efficacy to the DOTS server, per "Automatic
or Operator-Assisted CPE or PE Mitigators Request Upstream DDoS
Mitigation Services" in [I-D.ietf-dots-use-cases]. DOTS servers
MAY use the efficacy metric to adjust countermeasures activated on
a mitigator on behalf of a DOTS client.

OP-008 Conflict Detection and Notification: Multiple DOTS clients
controlled by a single administrative entity may send conflicting
mitigation requests for pool of protected resources, as a result
of misconfiguration, operator error, or compromised DOTS clients.

DOTS servers attempting to honor conflicting requests may flap
network route or DNS information, degrading the networks
attempting to participate in attack response with the DOTS
clients. DOTS servers SHALL detect such conflicting requests, and
SHALL notify the DOTS clients in conflict. The notification
SHOULD indicate the nature and scope of the conflict, for example,
the overlapping prefix range in a conflicting mitigation request.

OP-009: Lookup Caching: DOTS agents SHOULD cache resolved names, PKI
validation chains, and similarly queried data as necessary.
Network-based lookups and validation may be inhibited or
unavailable during an active attack due to link congestion. For
example, DOTS agents SHOULD cache resolved names and addresses of
peer DOTS agents, and SHOULD refer to those agents by IPv4
[RFC0791] or IPv6 address for all communications following initial
name resolution.

OP-010: Network Address Translator Traversal: The DOTS protocol MUST
operate over networks in which Network Address Translation (NAT)
is deployed. As UDP is the recommended transport for DOTS, all
considerations in "Middlebox Traversal Guidelines" in [RFC5405]
apply to DOTS. Regardless of transport, DOTS protocols MUST
follow established best common practices (BCPs) for NAT traversal.

2.3. Data channel requirements Channel Requirements

The data channel is intended to be used for bulk data exchanges
between DOTS agents. Unlike the signal channel, which must operate
nominally even when confronted with despite signal degradation due to
packet loss, the data channel is not expected to be constructed to
deal with attack conditions. As the primary function of the data
channel is data exchange, a reliable transport is required in order
for DOTS agents to detect data delivery success or failure.

The data channel should must be adaptable and extensible. We anticipate the data channel
will be used for such purposes as configuration or resource
discovery. For example, a DOTS client may submit to the DOTS server
a collection of prefixes it wants to refer to by alias when
requesting mitigation, to which the server would respond with a
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.
The transactional nature of such data exchanges suggests a separate
set of requirements for the data channel, while the potentially
sensitive content sent between DOTS agents requires extra precautions
to ensure data privacy and authenticity.

DATA-001 Reliable transport: Transmissions over the data channel may
MUST be transactional, requiring reliable, in-order packet
delivery.

DATA-002 Data privacy and integrity: Transmissions over the data
channel may is likely to contain sensitive operationally or privacy-sensitive
information or instructions from the remote DOTS agent. Theft or
modification of data channel transmissions could lead to
information leaks or malicious transactions on behalf of the
sending agent. (See Security
Considerations below.) agent (see Section 4 below). Consequently data sent over
the data channel MUST be encrypted and authenticated using current
industry best practices.

DATA-003 Mutual authentication: DOTS agents servers and relays MUST mutually
authenticate each other before enable
means to prevent leaking operationally or privacy-sensitive data.
Although administrative entities participating in DOTS may detail
what data may be exchanged over the data
channel. DOTS agents MAY take additional steps revealed to authorize data
exchange, as third-party DOTS agents, such
considerations are not in the prefix group example above, before accepting
data over the data channel. The form of authentication and
authorization is unspecified.

DATA-004 scope for this document.

DATA-003 Black- and whitelist management: DOTS servers SHOULD
provide methods for DOTS clients to manage black- and white-lists
of source addresses of traffic destined for addresses belonging addresses belonging to
a client.

For example, a DOTS client should be able to create a black- or
whitelist entry; retrieve a list of current entries from either
list; update the content of either list; and delete entries as
necessary.

How the DOTS server determines client ownership of address space
is not in scope.

2.4. Security requirements

DOTS must operate within a particularly strict security context, as
an insufficiently protected signal or data channel may be subject to
abuse, enabling or supplementing the very attacks DOTS purports to
mitigate.

SEC-001 Peer Mutual Authentication: DOTS agents MUST authenticate
each other before a DOTS session is considered valid. The method
of authentication is not specified, but should follow current
industry best practices with respect to any cryptographic
mechanisms to authenticate the remote peer.

SEC-002 Message Confidentiality, Integrity and Authenticity: DOTS
protocols MUST take steps to protect the confidentiality,
integrity and authenticity of messages sent between client and
server. While specific transport- and message-level security
options are not specified, the protocols MUST follow current
industry best practices for encryption and message authentication.

In order for DOTS protocols to
a client.

For example, a remain secure despite advancements
in cryptanalysis and traffic analysis, DOTS client should agents MUST be able to create a black- or
whitelist entry; retrieve a list of current entries from either
list; update
negotiate the content of either list; terms and delete entries as
necessary.

How the DOTS server determines client ownership mechanisms of address space
is not in scope.

2.4. Data model protocol security, subject
to the interoperability and signal message size requirements

TODO
above.

SEC-003 Message Replay Protection: In order to prevent a passive
attacker from capturing and replaying old messages, DOTS protocols
MUST provide a method for replay detection.

3. Congestion Control Considerations

The DOTS signal channel will not contribute measurably to link
congestion, as the protocol's transmission rate will be negligible
regardless of network conditions. Bulk data transfers are performed
over the data channel, which should use a reliable transport with
built-in congestion control mechanisms, such as TCP.

4. Security Considerations

DOTS is at risk from three primary attacks:

o DOTS agent impersonation,
traffic injection, and signaling blocking. impersonation

o Traffic injection

o Signaling blocking

The DOTS protocol MUST be designed for minimal data transfer to
address the blocking risk. Impersonation and traffic injection
mitigation can be managed through current secure communications best
practices. DOTS is not subject See Section 2.4 above for a detailed discussion.

5. Contributors

Med Boucadair

6. Acknowledgments

Thanks to
anything new in this area. One consideration could be Roman Danyliw and Matt Richardson for careful reading and
feedback.

7. Change Log

7.1. 01 revision

2016-03-21

o Reconciled terminology with -00 revision of
[I-D.ietf-dots-use-cases].

o Terminology clarification based on working group feedback.

o Moved security-related requirements to minimize separate section.

o Made resilience/robustness primary general requirement to align
with charter.

o Clarified support for unidirectional communication within the security technologies
bidirection signal channel.

o Added proposed operational requirement to support session
redirection.

o Added proposed operational requirement to support conflict
notification.

o Added proposed operational requirement to support mitigation
lifetime in use at any one time. The more needed,
the greater the risk of failures coming mitigation requests.

o Added proposed operational requirement to support mitigation
efficacy reporting from assumptions on one
technology providing protection that it does not in the presence DOTS clients.

o Added proposed operational requirement to cache lookups of
another technology.

5. Change Log

5.1. all
kinds.

o Added proposed operational requirement regarding NAT traversal.

o Removed redundant mutual authentication requirement from data
channel requirements.

7.2. 00 revision

2015-10-15

5.2.

7.3. Initial revision

2015-09-24 Andrew Mortensen

8. References

6.1.

8.1. Normative References

[RFC0768] Postel, J., "User Datagram Protocol", STD 6, RFC 768, DOI
10.17487/RFC0768, August 1980,
<http://www.rfc-editor.org/info/rfc768>.

[RFC0793] Postel, J., "Transmission Control Protocol", STD 7, RFC
793, DOI 10.17487/RFC0793, September 1981,
<http://www.rfc-editor.org/info/rfc793>.

[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/
RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.

6.2.

[RFC5405] Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
for Application Designers", BCP 145, RFC 5405, DOI
10.17487/RFC5405, November 2008,
<http://www.rfc-editor.org/info/rfc5405>.

8.2. Informative References

[I-D.ietf-dots-use-cases]
Dobbins, R., Fouant, S., Migault, D., Moskowitz, R.,
Teague, N., and L. Xia, "Use cases for DDoS Open Threat
Signaling", draft-ietf-dots-use-cases-00 (work in
progress), October 2015.

[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, DOI
10.17487/RFC0791, September 1981,
<http://www.rfc-editor.org/info/rfc791>.

[RFC1034] Mockapetris, P., "Domain names - concepts and facilities",
STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987,
<http://www.rfc-editor.org/info/rfc1034>.

[RFC1518] Rekhter, Y. and T. Li, "An Architecture for IP Address
Allocation with CIDR", RFC 1518, DOI 10.17487/RFC1518,
September 1993, <http://www.rfc-editor.org/info/rfc1518>.

[RFC1519] Fuller, V., Li, T., Yu, J., and K. Varadhan, "Classless
Inter-Domain Routing (CIDR): an Address Assignment and
Aggregation Strategy", RFC 1519, DOI 10.17487/RFC1519,
September 1993, <http://www.rfc-editor.org/info/rfc1519>.

[RFC2373] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, DOI 10.17487/RFC2373, July 1998,
<http://www.rfc-editor.org/info/rfc2373>.

[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.

[RFC3261] Rosenberg, J., Schulzrinne, H., Camarillo, G., Johnston,
A., Peterson, J., Sparks, R., Handley, M., and E.
Schooler, "SIP: Session Initiation Protocol", RFC 3261,
DOI 10.17487/RFC3261, June 2002,
<http://www.rfc-editor.org/info/rfc3261>.

[RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
Border Gateway Protocol 4 (BGP-4)", RFC 4271, DOI
10.17487/RFC4271, January 2006,
<http://www.rfc-editor.org/info/rfc4271>.

[RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet
Denial-of-Service Considerations", RFC 4732, DOI 10.17487/
RFC4732, December 2006,
<http://www.rfc-editor.org/info/rfc4732>.

Authors' Addresses

Andrew Mortensen
Arbor Networks, Inc.
2727 S. State St
Ann Arbor, MI 48104
United States

Email: amortensen@arbor.net

Robert Moskowitz
HTT Consulting
Oak Park, MI 42837
United States

Email: rgm@htt-consult.com
Tirumaleswar Reddy
Cisco Systems, Inc.
Cessna Business Park, Varthur Hobli
Sarjapur Marathalli Outer Ring Road
Bangalore, Karnataka 560103
India

Email: tireddy@cisco.com