Use cases for DDoS Open Threat Signaling
Arbor Networks
30 Raffles Place
Level 17 Chevron House
Singapore 048622
Singapore
rdobbins@arbor.net
stefan.fouant@copperriverit.com
Ericsson
8400 boulevard Decarie
Montreal
QC
H4P 2N2
Canada
+1 514-452-2160
daniel.migault@ericsson.com
HTT Consulting
Oak Park
MI
48237
USA
rgm@labs.htt-consult.com
Verisign Inc
12061 Bluemont Way
Reston
VA
20190
USA
+44 791 763 5384
nteague@verisign.com
Huawei
No. 101, Software Avenue, Yuhuatai District
Nanjing
China
Frank.xialiang@huawei.com
NTT Communications
GranPark 16F 3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
kaname@nttv6.jp
Security Area
DOTS WG
RFC
Request for Comments
I-D
Internet-Draft
The DDoS Open Threat Signaling (DOTS) effort is intended to provide
a protocol that facilitates interoperability between multivendor
solutions/services. This document presents use cases to evaluate the
interactions expected between the DOTS components as well as the DOTS
exchanges. The purpose of the use cases is to identify the interacting
DOTS component, how they collaborate and what are the types of
information to be exchanged.
Currently, distributed denial-of-service (DDoS) attack mitigation
solutions/services are largely based upon siloed, proprietary
communications paradigms which result in vendor/service lock-in. As a
side-effect, this makes the configuration, provisioning, operation, and
activation of these solutions a highly manual and often time- consuming
process. Additionally, coordination of multiple DDoS mitigation
solutions/services simultaneously engaged in defending the same
organization against DDoS attacks is fraught with both technical and
process-related hurdles. This greatly increase operational complexity
and often results in suboptimal DDoS attack mitigation efficacy.
The DDoS Open Threat Signaling (DOTS) effort is intended to provide a
protocol that facilitates interoperability between multivendor DDoS
mitigation solutions/services. As DDoS solutions/services are broadly
heterogeneous among different vendors, the primary goal for DOTS is to
provide a high level interaction with these DDoS solutions/services such
as initiating or terminating DDoS mitigation assistance.
It should be noted that DOTS is not in and of itself intended to
perform orchestration functions duplicative of the functionality being
developed by the [I2NSF] WG; rather, DOTS is intended to allow devices,
services, and applications to request DDoS attack mitigation assistance
and receive mitigation status updates from systems of this nature.
The use cases presented in the document are intended to provide
examples of communications interactions DOTS-enabled nodes in both
inter- and intra-organizational DDoS mitigation scenarios. These use
cases are expected to provide inputs for the design of the DOTS
protocol(s).
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 RFC 2119.
This document makes use of the same terminology and definitions as
, except where noted.
Inter-organizational: a DOTS communications relationship between
distinct organizations with separate spans of administrative control.
Typical inter-organizational DOTS communication relationships would be
between a DDoS mitigation service provider and an end-customer
organizational which requires DDoS mitigation assistance; between
multiple DDoS mitigation service providers coordinating mutual defense
of a mutual end-customer; or between DDoS mitigation service providers
which are requesting additional DDoS mitigation assistance in for
attacks which exceed their inherent DDoS mitigation capacities and/or
capabilities.
Intra-organizational: a DOTS communications relationship between
various elements within a single span of administrative control. A
typical intra-organizational DOTS communications relationship would be
between DOTS clients, DOTS gateways, and DOTS servers within the same
organization.
This section provides a high-level description of scenarios addressed
by DOTS. In both sections, the scenarios are provided in order to
illustrate the use of DOTS in typical DDoS attack scenarios. They are
not definitive, and other use cases are expected to emerge with
widespread DOTS deployment.
All scenarios present a coordination between the targeted
organization, the DDoS attack telemetry and the mitigator. The
coordination and communication between these entity depends, for example
on the characteristic or functionality of the equipment, the reliability
of the information provided by DDoS attack telemetry, and the business
relationship between the DDoS target domain and the mitigator.
More explicitly, in some cases, the DDoS attack telemetry may simply
activate a DDoS mitigation, whereas in other cases, it may collaborate
by providing some information about an attack. In some cases, the DDoS
mitigation may be orchestrated, which includes selecting a specific
appliance as well as starting/ending a mitigation.
In this scenario, an enterprise network with self-hosted
Internet-facing properties such as Web servers, authoritative DNS
servers, and VoIP PBXes has an intelligent DDoS mitigation system (IDMS)
deployed to protect those servers and applications from DDoS attacks.
In addition to their on-premise DDoS defense capability, they have
contracted with their Internet transit provider for DDoS mitigation
services which threaten to overwhelm their transit link bandwidth.
The IDMS is configured such that if the incoming Internet traffic
volume exceeds 50% of the provisioned upstream Internet transit link
capacity, the IDMS will request DDoS mitigation assistance from the
upstream transit provider.
The communication to trigger, manage, and finalize a DDoS mitigation
between the enterprise IDMS and the transit provider is performed using
DOTS. The enterprise IDMS implements a DOTS client while the transit
provider implements a DOTS server.
When the IDMS detects an inbound DDoS attack targeting the enterprise
servers and applications, it immediately begins mitigating the attack.
During the course of the attack, the inbound traffic volume exceeds
the 50% threshold; the IDMS DOTS client signals the DOTS server on the
upstream transit provider network to initiate DDoS mitigation. The DOTS
server signals the DOTS client that it can service this request, and
mitigation is initiated on the transit provider network.
Over the course of the attack, the DOTS server on the transit
provider network periodically signals the DOTS client on the enterprise
IDMS in order to provide mitigation status information, statistics
related to DDoS attack traffic mitigation, and related information. Once
the DDoS attack has ended, the DOTS server signals the enterprise IDMS
DOTS client that the attack has subsided.
The enterprise IDMS then requests that DDoS mitigation services on
the upstream transit provider network be terminated. The DOTS server on
the transit provider network receives this request, communicates with
the transit provider orchestration system controlling its DDoS
mitigation system to terminate attack mitigation, and once the
mitigation has ended, confirms the end of upstream DDoS mitigation
service to the enterprise IDMS DOTS client.
This use case details an enterprise that has a local DDoS detection
and classification capability and may or may not have a mitigation
capability. The enterprise is contracted with a cloud DDoS mitigation
provider who can redirect (offramp) traffic away from the enterprise,
provide scrubbing services and return clean traffic back to the
enterprise (onramp) on an ad-hoc, on demand basis.
The enterprise may, either by hard coding or on a case by case basis,
determine thresholds at which a request for mitigation is triggered
indicating to the cloud provider that traffic should be redirected and
scrubbed.
The communication to trigger, manage, and finalize a DDoS mitigation
between the enterprise and the Cloud provider is performed using DOTS.
The enterprise implements a DOTS client while the Cloud Provider
implements a DOTS server.
The enterprise detection and classification systems encompass a DOTS
client and the cloud provider a DOTS server.
When an attack is detected an automated or manual DOTS mitigation request
will be generatd and sent to the cloud
provider. The cloud provider will assess the request for validity and
if passed a mitigation action may then be initiated. This
action will usually involve the offramp of all traffic destined to the
target for further scrutiny and filtering by the cloud provider. This
should not only result in an alleviation of pressure on the enterprise
network but also on its upstream provider and peers.
The cloud provider should signal via DOTS to the enterprise that a
mitigation request has been received and acted upon and should also
include a basic situational status of the attack. The cloud provider
may respond periodically with additional updates on the status to enable
the enterprise to make an informed decision on whether to maintain or
cancel the mitigation. An alternative approach would be for the DOTS
client mitigation request to include a time to live (ttl) for the
mitigation which may be extended by the client should the attack still
be ongoing as the ttl reaches expiration.
A variation of this use case may be that the enterprise is providing
a flow based monitoring and analysis service to customers whose networks
may be protected by any one of a number of 3rd party providers. The
enterprise in question may integrate with these 3rd party providers
using DOTS and signal accordingly when a customer is attacked - the
enterprise may then manage the life-cycle of the attack on behalf of the
enterprise.
In this use case home networks or small businesses networks (SOHO),
subscribe with their upstream ISP a DDoS mitigation service.
Home networks run with limited bandwidth as well as limited routing
resources, while they are expected to provide services reachable from
the outside . This makes such organizations some
easy targets to DDoS attacks. In addition, these DDoS attacks might even
not be noticed by the upstream ISP.
This scenario is considered as an intra-domain as ISPs have a
specific relationship with these customers. The ISP is the connectivity
provider, and in some cases, they even provides the CPE with a set of
associated services. Moreover, in case of any connectivity issue the
customer is likely to call the hotline. In order to improve the QoS of
the connectivity as well as to automate the request for DDoS mitigation,
ISP is likely to consider a standard mean for CPEs to notify when they
are under a suspected DDoS. Such notification may be triggered
automatically or manually. As the ISP and the customer share a common
interest in mitigating the DDoS attack, this slightly differs from cases
where a contract is negotiated with a third party, such as in the
inter-domain use cases.
In most cases, CPEs are unlikely to diagnose whether an DDoS attack
is ongoing or not and simply rely on the upstream equipment provided by the ISP
for detection and potential mitigation.
The DDoS Mitigation service of the ISP may be hard coded or may be
configured by the customer manually or automatically while the CPE is
being connected to the Internet -- eventually the DHCP server may
provide the DDoS Mitigation service via specific DHCP options.
The communication to trigger a DDoS mitigation between the home
network and the ISP is performed using DOTS. The home network CPE
implements a DOTS client while the ISP implements a DOTS server.
The DOTS Client on the CPE monitors the status of CPE's resource
and link bandwidth usage. If something unusual happens based on preconfigured
throughput or some heuristics methods, the DOTS Client sends a DOTS mitigation
request to the ISP DOTS Server. Typically, a default configuration with no additional
information associated to the DOTS mitigation request is expected. The ISP
derives traffic to mitigate from the CPE IP address.
In some cases, the DOTS mitigation request contains options such as
some IP addresses or prefixes that belongs to a whitelist or
respectively to a blacklist. In this case, the white and black lists are
not associated to some analysis performed by the CPE -- as the CPE is
clearly not expected to analyze such attacks. Instead these are part of
some configuration parameters. For example, in the case of small
business, one may indicate specific legitimate IP addresses such as
those used for VPNs, or third party services the company is likely to
set a session. Similarly, the CPE may provides the IP addresses of the
assets to be protected inside the network. Such options may include the
IP address as well as a service description. Similarly to the previous
blacklist and whitelist, such information are not derived from a traffic
analysis performed by the CPE, but instead are more related to
configuration parameters.
Upon receiving the DOTS mitigation request, the ISP acknowledges its
reception and confirms DDoS mitigation starts or not. Such feed back is
mostly to avoid retransmission of the request.
Note that the ISP is connected to multiple CPEs and as such the CPE
can potentially perform DDoS attack to the DOTS server. ISP may use relays to absorbs the
traffic. In addition, such attack may be triggered by a large scale DDoS
attack, which is expected to be detected and mitigated by the upstream
architecture.
ISP may activate mitigation for the traffic associated to the CPE
sending the alert or instead to the traffic associated to all CPE. Such
decisions are not part of DOTS, but instead depend on the policies of
the ISP network administrator.
It is unlikely the CPE will follow the status of the mitigation. The
ISP is only expected to inform the CPE the mitigation has been
stopped.
Upon receipt of such notification the CPE may re-activate the
monitoring jobs and thus is likely to provide some further DOTS
alert.
In this use case, one or multiple telemetry systems or monitoring
devices like a flow collector monitor a network -- typically an ISP
network. Upon detection of a DDoS attack, these telemetry systems alert
an orchestrator in charge of coordinating the various DDoS mitigation
systems within the domain. The telemetry systems may be configured to
provide some necessary or useful pieces of informations, such as a
preliminary analysis of the observation to the orchestrator.
The orchestrator analyses the various information it receives from
specialized equipements, and elaborates one or multiple DDoS mitigation
strategies. In some case, a manual confirmation may also be required to
chose a proposed strategy or to start the DDoS mitigation.
The DDoS mitigation may consists in multiple steps such as configuring
the network, the various hardware or already instantiated DDoS
mitigation functions. In some cases, some specific virtual DDoS
mitigation functions need to be instantiated and properly chained
between each other. Eventually, the coordination of the mitigation may
involved external DDoS resources such as a transit provider or a cloud provider .
The communication to trigger a DDoS mitigation between the telemetry
and monitoring systems and the orchestrator is performed using DOTS. The
telemetry systems implements a DOTS client while the Orchestrator
implements a DOTS server.
The communication between to select a DDoS strategy by a network
administrator and the orchestrator is also performed using DOTS. The
network administrator via its web interfaces implements a DOTS client
while the Orchestrator implements a DOTS server.
The communication between the Orchestrator and the DDoS mitigation
systems is performed using DOTS. The Orchestrator implements a DOTS
client while the DDoS mitigation systems implement a DOTS server.
The configuration aspects of each DDoS mitigation systems, as well as
the instantiations of DDoS mitigation functions or network configuration
is not part of DOTS. Similarly the discovery of the available DDoS
mitigation functions is not pat of DOTS.
The Telemetry or monitoring systems monitors each various traffic
network and each performs their measurement tasks. They are configure so
that when an event or some measurements reach a predefined level to
report a DOTS mitigation request to the orchestrator. The DOTS
mitigation request may be associated with some element such as specific
reporting, or analysis.
Upon receipt of the DOTS mitigation request from the telemetry
system, the orchestrator responds with an acknowledgement, to avoid
retransmission of the request for mitigation. The status of the DDoS
mitigation indicates the orchestrator is in an analysing phase. The
orchestrator begins collecting various informations from various
telemetry systems on the network in order to correlate the measurements
and provide an analyse of the event. Eventually, the orchestrator may
ask additional informations to the telemetry system that just sent the
DOTS request, however, the collection of these information is performed
outside DOTS.
The orchestrator may be configured to start a DDoS mitigation upon
approval from a network administrator. The analysis from the
orchestrator is reported to the network administrator via a web
interface. If the network administrator decides to start the mitigation,
she order through her web interface a DOTS client to send a request for
DDoS mitigation. This request is expected to be associated with a
context that identifies the DDoS mitigation selected.
Upon receiving the DOTS request for DDoS mitigation from the network
administrator, the orchestrator orchestrates the DDoS mitigation
according to the specified strategy. It status first indicates the DDoS
mitigation is starting while not effective. In fact the orchestrator is
expected to proceed to a significant number of configurations.
Orchestration of the DDoS mitigation systems works similarly as
described in or . The orchestrator indicates with its status the
DDoS Mitigation is effective.
When the DDoS mitigation is finished on the DDoS mitigation systems,
the orchestrator indicates to the Telemetry systems as well as to the
network administrator the DDoS mitigation is finished.
DOTS is at risk from three primary attacks: DOTS agent
impersonation, traffic injection, and 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 to anything new in this area. One consideration could be to
minimize the security technologies in use at any one time. The more
needed, the greater the risk of failures coming from assumptions on one
technology providing protection that it does not in the presence of
another technology.
Additional details of DOTS security requirements may be found in
.
No IANA considerations exist for this document at this time.
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