< draft-ietf-dots-signal-channel-12.txt   draft-ietf-dots-signal-channel-13.txt >
DOTS T. Reddy DOTS T. Reddy
Internet-Draft McAfee Internet-Draft McAfee
Intended status: Standards Track M. Boucadair Intended status: Standards Track M. Boucadair
Expires: June 9, 2018 Orange Expires: June 16, 2018 Orange
P. Patil P. Patil
Cisco Cisco
A. Mortensen A. Mortensen
Arbor Networks, Inc. Arbor Networks, Inc.
N. Teague N. Teague
Verisign, Inc. Verisign, Inc.
December 6, 2017 December 13, 2017
Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal
Channel Channel
draft-ietf-dots-signal-channel-12 draft-ietf-dots-signal-channel-13
Abstract Abstract
This document specifies the DOTS signal channel, a protocol for This document specifies the DOTS signal channel, a protocol for
signaling the need for protection against Distributed Denial-of- signaling the need for protection against Distributed Denial-of-
Service (DDoS) attacks to a server capable of enabling network Service (DDoS) attacks to a server capable of enabling network
traffic mitigation on behalf of the requesting client. traffic mitigation on behalf of the requesting client.
A companion document defines the DOTS data channel, a separate A companion document defines the DOTS data channel, a separate
reliable communication layer for DOTS management and configuration. reliable communication layer for DOTS management and configuration
purposes.
Editorial Note (To be removed by RFC Editor) Editorial Note (To be removed by RFC Editor)
Please update these statements with the RFC number to be assigned to Please update these statements with the RFC number to be assigned to
this document: this document:
o "This version of this YANG module is part of RFC XXXX;" o "This version of this YANG module is part of RFC XXXX;"
o "RFC XXXX: Distributed Denial-of-Service Open Threat Signaling o "RFC XXXX: Distributed Denial-of-Service Open Threat Signaling
(DOTS) Signal Channel"; (DOTS) Signal Channel";
skipping to change at page 2, line 20 skipping to change at page 2, line 20
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 9, 2018. This Internet-Draft will expire on June 16, 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
skipping to change at page 2, line 45 skipping to change at page 2, line 45
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Notational Conventions and Terminology . . . . . . . . . . . 5 2. Notational Conventions and Terminology . . . . . . . . . . . 5
3. Design Overview . . . . . . . . . . . . . . . . . . . . . . . 6 3. Design Overview . . . . . . . . . . . . . . . . . . . . . . . 6
4. DOTS Signal Channel: Messages & Behaviors . . . . . . . . . . 8 4. DOTS Signal Channel: Messages & Behaviors . . . . . . . . . . 8
4.1. DOTS Server(s) Discovery . . . . . . . . . . . . . . . . 8 4.1. DOTS Server(s) Discovery . . . . . . . . . . . . . . . . 8
4.2. CoAP URIs . . . . . . . . . . . . . . . . . . . . . . . . 8 4.2. CoAP URIs . . . . . . . . . . . . . . . . . . . . . . . . 8
4.3. Happy Eyeballs for DOTS Signal Channel . . . . . . . . . 8 4.3. Happy Eyeballs for DOTS Signal Channel . . . . . . . . . 9
4.4. DOTS Mitigation Methods . . . . . . . . . . . . . . . . . 10 4.4. DOTS Mitigation Methods . . . . . . . . . . . . . . . . . 10
4.4.1. Request Mitigation . . . . . . . . . . . . . . . . . 10 4.4.1. Request Mitigation . . . . . . . . . . . . . . . . . 11
4.4.2. Retrieve Information Related to a Mitigation . . . . 19 4.4.2. Retrieve Information Related to a Mitigation . . . . 20
4.4.3. Efficacy Update from DOTS Clients . . . . . . . . . . 27 4.4.3. Efficacy Update from DOTS Clients . . . . . . . . . . 28
4.4.4. Withdraw a Mitigation . . . . . . . . . . . . . . . . 29 4.4.4. Withdraw a Mitigation . . . . . . . . . . . . . . . . 30
4.5. DOTS Signal Channel Session Configuration . . . . . . . . 31 4.5. DOTS Signal Channel Session Configuration . . . . . . . . 32
4.5.1. Discover Configuration Parameters . . . . . . . . . . 32 4.5.1. Discover Configuration Parameters . . . . . . . . . . 33
4.5.2. Convey DOTS Signal Channel Session Configuration . . 34 4.5.2. Convey DOTS Signal Channel Session Configuration . . 35
4.5.3. Delete DOTS Signal Channel Session Configuration . . 39 4.5.3. Delete DOTS Signal Channel Session Configuration . . 40
4.6. Redirected Signaling . . . . . . . . . . . . . . . . . . 39 4.6. Redirected Signaling . . . . . . . . . . . . . . . . . . 40
4.7. Heartbeat Mechanism . . . . . . . . . . . . . . . . . . . 41 4.7. Heartbeat Mechanism . . . . . . . . . . . . . . . . . . . 42
5. DOTS Signal Channel YANG Module . . . . . . . . . . . . . . . 42 5. DOTS Signal Channel YANG Module . . . . . . . . . . . . . . . 43
5.1. Tree Structure . . . . . . . . . . . . . . . . . . . . . 42 5.1. Tree Structure . . . . . . . . . . . . . . . . . . . . . 43
5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 44 5.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 45
6. Mapping Parameters to CBOR . . . . . . . . . . . . . . . . . 53 6. Mapping Parameters to CBOR . . . . . . . . . . . . . . . . . 55
7. (D)TLS Protocol Profile and Performance Considerations . . . 55 7. (D)TLS Protocol Profile and Performance Considerations . . . 56
7.1. (D)TLS Protocol Profile . . . . . . . . . . . . . . . . . 55 7.1. (D)TLS Protocol Profile . . . . . . . . . . . . . . . . . 56
7.2. (D)TLS 1.3 Considerations . . . . . . . . . . . . . . . . 56 7.2. (D)TLS 1.3 Considerations . . . . . . . . . . . . . . . . 58
7.3. MTU and Fragmentation . . . . . . . . . . . . . . . . . . 57 7.3. MTU and Fragmentation . . . . . . . . . . . . . . . . . . 59
8. Mutual Authentication of DOTS Agents & Authorization of DOTS 8. Mutual Authentication of DOTS Agents & Authorization of DOTS
Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 59 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 61
9.1. DOTS Signal Channel UDP and TCP Port Number . . . . . . . 59 9.1. DOTS Signal Channel UDP and TCP Port Number . . . . . . . 61
9.2. Well-Known 'dots' URI . . . . . . . . . . . . . . . . . . 59 9.2. Well-Known 'dots' URI . . . . . . . . . . . . . . . . . . 61
9.3. CoAP Response Code . . . . . . . . . . . . . . . . . . . 59 9.3. CoAP Response Code . . . . . . . . . . . . . . . . . . . 61
9.4. DOTS Signal Channel CBOR Mappings Registry . . . . . . . 60 9.4. DOTS Signal Channel CBOR Mappings Registry . . . . . . . 62
9.4.1. Registration Template . . . . . . . . . . . . . . . . 60 9.4.1. Registration Template . . . . . . . . . . . . . . . . 62
9.4.2. Initial Registry Contents . . . . . . . . . . . . . . 60 9.4.2. Initial Registry Contents . . . . . . . . . . . . . . 62
9.5. DOTS Signal Channel YANG Module . . . . . . . . . . . . . 66 9.5. DOTS Signal Channel YANG Module . . . . . . . . . . . . . 68
10. Implementation Status . . . . . . . . . . . . . . . . . . . . 66 10. Implementation Status . . . . . . . . . . . . . . . . . . . . 68
10.1. nttdots . . . . . . . . . . . . . . . . . . . . . . . . 67 10.1. nttdots . . . . . . . . . . . . . . . . . . . . . . . . 69
11. Security Considerations . . . . . . . . . . . . . . . . . . . 67 11. Security Considerations . . . . . . . . . . . . . . . . . . . 69
12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 68 12. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 70
13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 68 13. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 70
14. References . . . . . . . . . . . . . . . . . . . . . . . . . 68 14. References . . . . . . . . . . . . . . . . . . . . . . . . . 71
14.1. Normative References . . . . . . . . . . . . . . . . . . 68 14.1. Normative References . . . . . . . . . . . . . . . . . . 71
14.2. Informative References . . . . . . . . . . . . . . . . . 70 14.2. Informative References . . . . . . . . . . . . . . . . . 73
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 76
1. Introduction 1. Introduction
A distributed denial-of-service (DDoS) attack is an attempt to make A distributed denial-of-service (DDoS) attack is an attempt to make
machines or network resources unavailable to their intended users. machines or network resources unavailable to their intended users.
In most cases, sufficient scale can be achieved by compromising In most cases, sufficient scale can be achieved by compromising
enough end-hosts and using those infected hosts to perpetrate and enough end-hosts and using those infected hosts to perpetrate and
amplify the attack. The victim in this attack can be an application amplify the attack. The victim in this attack can be an application
server, a host, a router, a firewall, or an entire network. server, a host, a router, a firewall, or an entire network.
Network applications have finite resources like CPU cycles, number of Network applications have finite resources like CPU cycles, the
processes or threads they can create and use, maximum number of number of processes or threads they can create and use, the maximum
simultaneous connections it can handle, limited resources of the number of simultaneous connections it can handle, the limited
control plane, etc. When processing network traffic, such resources of the control plane, etc. When processing network
applications are supposed to use these resources to offer the traffic, such applications are supposed to use these resources to
intended task in the most efficient fashion. However, a DDoS offer the intended task in the most efficient manner. However, a
attacker may be able to prevent an application from performing its DDoS attacker may be able to prevent an application from performing
intended task by causing the application to exhaust the finite supply its intended task by making the application exhaust its finite
of a specific resource. resources.
TCP DDoS SYN-flood, for example, is a memory-exhaustion attack on the TCP DDoS SYN-flood, for example, is a memory-exhausting attack while
victim and ACK-flood is a CPU exhaustion attack on the victim ACK-flood is a CPU-exhausting attack [RFC4987]. Attacks on the link
[RFC4987]. Attacks on the link are carried out by sending enough are carried out by sending enough traffic so that the link becomes
traffic such that the link becomes excessively congested, and congested, thereby likely causing packet loss for legitimate traffic.
legitimate traffic suffers high packet loss. Stateful firewalls can Stateful firewalls can also be attacked by sending traffic that
also be attacked by sending traffic that causes the firewall to hold causes the firewall to maintain an excessive number of states that
excessive state. The firewall then runs out of memory, and can no may jeopardize the firewall's operation overall, besides like
longer instantiate the state required to pass legitimate flows. performance impacts. The firewall then runs out of memory, and can
Other possible DDoS attacks are discussed in [RFC4732]. no longer instantiate the states required to process legitimate
flows. Other possible DDoS attacks are discussed in [RFC4732].
In many cases, it may not be possible for network administrators to In many cases, it may not be possible for network administrators to
determine the causes of an attack, but instead just realize that determine the cause(s) of an attack. They may instead just realize
certain resources seem to be under attack. This document defines a that certain resources seem to be under attack. This document
lightweight protocol permitting a DOTS client to request mitigation defines a lightweight protocol that allows a DOTS client to request
from one or more DOTS servers for protection against detected, mitigation from one or more DOTS servers for protection against
suspected, or anticipated attacks. This protocol enables cooperation detected, suspected, or anticipated attacks. This protocol enables
between DOTS agents to permit a highly-automated network defense that cooperation between DOTS agents to permit a highly-automated network
is robust, reliable, and secure. defense that is robust, reliable, and secure.
An example of network diagram showing a deployment of DOTS agents is An example of a network diagram that illustrates a deployment of DOTS
shown in Figure 1. In this example, the DOTS server is operating on agents is shown in Figure 1. In this example, a DOTS server is
the access network. The DOTS client is located on the LAN (Local operating on the access network. A DOTS client is located on the LAN
Area Network), while a DOTS gateway is embedded in the CPE (Customer (Local Area Network), while a DOTS gateway is embedded in the CPE
Premises Equipment). (Customer Premises Equipment).
Network Network
Resource CPE router Access network __________ Resource CPE router Access network __________
+-----------+ +--------------+ +-------------+ / \ +-----------+ +--------------+ +-------------+ / \
| |____| |_______| |___ | Internet | | |____| |_______| |___ | Internet |
|DOTS client| | DOTS gateway | | DOTS server | | | |DOTS client| | DOTS gateway | | DOTS server | | |
| | | | | | | | | | | | | | | |
+-----------+ +--------------+ +-------------+ \__________/ +-----------+ +--------------+ +-------------+ \__________/
Figure 1: Sample DOTS Deployment (1) Figure 1: Sample DOTS Deployment (1)
The DOTS server can also be reachable over the Internet, as depicted DOTS servers can also be reachable over the Internet, as depicted in
in Figure 2. Figure 2.
Network DDoS mitigation Network DDoS mitigation
Resource CPE router __________ service Resource CPE router __________ service
+-----------+ +-------------+ / \ +-------------+ +-----------+ +-------------+ / \ +-------------+
| |____| |_______| |___ | | | |____| |_______| |___ | |
|DOTS client| |DOTS gateway | | Internet | | DOTS server | |DOTS client| |DOTS gateway | | Internet | | DOTS server |
| | | | | | | | | | | | | | | |
+-----------+ +-------------+ \__________/ +-------------+ +-----------+ +-------------+ \__________/ +-------------+
Figure 2: Sample DOTS Deployment (2) Figure 2: Sample DOTS Deployment (2)
In typical deployments, the DOTS client belongs to a different In typical deployments, the DOTS client belongs to a different
administrative domain than the DOTS server. For example, the DOTS administrative domain than the DOTS server. For example, the DOTS
client is embedded in a firewall protecting services owned and client is embedded in a firewall protecting services owned and
operated by a domain, while the DOTS server is owned and operated by operated by a domain, while the DOTS server is owned and operated by
a different domain providing DDoS mitigation services. That domain a different domain providing DDoS mitigation services. The latter
providing DDoS mitigation service might, or might not, provide might or might not provide connectivity services to the network
connectivity service to the network hosting the DOTS client. hosting the DOTS client.
The DOTS server may (not) be co-located with the DOTS mitigator. In The DOTS server may (not) be co-located with the DOTS mitigator. In
typical deployments, the DOTS server belongs to the same typical deployments, the DOTS server belongs to the same
administrative domain as the mitigator. The DOTS client can administrative domain as the mitigator. The DOTS client can
communicate directly with a DOTS server or indirectly via a DOTS communicate directly with a DOTS server or indirectly via a DOTS
gateway. gateway.
The document adheres to the DOTS architecture The document adheres to the DOTS architecture
[I-D.ietf-dots-architecture]. The requirements for DOTS signal [I-D.ietf-dots-architecture]. The requirements for DOTS signal
channel protocol are obtained from [I-D.ietf-dots-requirements]. channel protocol are documented in [I-D.ietf-dots-requirements].
This document satisfies all the use cases discussed in This document satisfies all the use cases discussed in
[I-D.ietf-dots-use-cases]. [I-D.ietf-dots-use-cases].
This document focuses on the DOTS signal channel. This is a This document focuses on the DOTS signal channel. This is a
companion document to the DOTS data channel specification companion document of the DOTS data channel specification
[I-D.ietf-dots-data-channel] that defines a configuration and bulk [I-D.ietf-dots-data-channel] that defines a configuration and a bulk
data exchange mechanism supporting the DOTS signal channel. data exchange mechanism supporting the DOTS signal channel.
2. Notational Conventions and Terminology 2. Notational Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
(D)TLS is used for statements that apply to both Transport Layer (D)TLS is used for statements that apply to both Transport Layer
skipping to change at page 6, line 15 skipping to change at page 6, line 15
The reader should be familiar with the terms defined in The reader should be familiar with the terms defined in
[I-D.ietf-dots-architecture]. [I-D.ietf-dots-architecture].
The meaning of the symbols in YANG tree diagrams is defined in The meaning of the symbols in YANG tree diagrams is defined in
[I-D.ietf-netmod-yang-tree-diagrams]. [I-D.ietf-netmod-yang-tree-diagrams].
3. Design Overview 3. Design Overview
The DOTS signal channel is built on top of the Constrained The DOTS signal channel is built on top of the Constrained
Application Protocol (CoAP) [RFC7252], a lightweight protocol Application Protocol (CoAP) [RFC7252], a lightweight protocol
originally designed for constrained devices and networks. CoAP's originally designed for constrained devices and networks. The many
expectation of packet loss, support for asynchronous non-confirmable features of CoAP (expectation of packet loss, support for
messaging, congestion control, small message overhead limiting the asynchronous non-confirmable messaging, congestion control, small
need for fragmentation, use of minimal resources, and support for message overhead limiting the need for fragmentation, use of minimal
(D)TLS make it a good foundation on which to build the DOTS signaling resources, and support for (D)TLS) makes it a good candidate to build
mechanism. the DOTS signaling mechanism from.
The DOTS signal channel is layered on existing standards (Figure 3). The DOTS signal channel is layered on existing standards (Figure 3).
+--------------+ +--------------+
| DOTS | | DOTS |
+--------------+ +--------------+
| CoAP | | CoAP |
+--------------+ +--------------+
| TLS | DTLS | | TLS | DTLS |
+--------------+ +--------------+
| TCP | UDP | | TCP | UDP |
+--------------+ +--------------+
| IP | | IP |
+--------------+ +--------------+
Figure 3: Abstract Layering of DOTS signal channel over CoAP over Figure 3: Abstract Layering of DOTS signal channel over CoAP over
(D)TLS (D)TLS
By default, DOTS signal channel MUST run over port number TBD as By default, a DOTS signal channel MUST run over port number TBD as
defined in Section 9.1, for both UDP and TCP, unless the DOTS server defined in Section 9.1, for both UDP and TCP, unless the DOTS server
has mutual agreement with its DOTS clients to use a port number other has a mutual agreement with its DOTS clients to use a different port
than TBD for DOTS signal channel, or DOTS clients supports means to number. DOTS clients may alternatively support means to dynamically
dynamically discover the ports used by their DOTS servers. In order discover the ports used by their DOTS servers. In order to use a
to use a distinct port number (vs. TBD), DOTS clients and servers distinct port number (as opposed to TBD), DOTS clients and servers
should support a configurable parameter to supply the port number to should support a configurable parameter to supply the port number to
use. The rationale for not using the default port number 5684 use. The rationale for not using the default port number 5684
((D)TLS CoAP) is to allow for differentiated behaviors in deployment ((D)TLS CoAP) is to allow for differentiated behaviors in
contexts where both a DOTS gateway and an IoT gateway (e.g., Figure 3 environments where both a DOTS gateway and an IoT gateway (e.g.,
of [RFC7452]) are present. Figure 3 of [RFC7452]) are present.
The signal channel is initiated by the DOTS client (Section 4.4). The signal channel is initiated by the DOTS client (Section 4.4).
Once the signal channel is established, the DOTS agents periodically Once the signal channel is established, the DOTS agents periodically
send heartbeats to keep the channel active (Section 4.7). At any send heartbeats to keep the channel active (Section 4.7). At any
time, the DOTS client may send a mitigation request message to a DOTS time, the DOTS client may send a mitigation request message to a DOTS
server over the active channel. While mitigation is active, due to server over the active channel. While mitigation is active because
the higher likelihood of packet loss during a DDoS attack, the DOTS of the higher likelihood of packet loss during a DDoS attack, the
server periodically sends status messages to the client, including DOTS server periodically sends status messages to the client,
basic mitigation feedback details. Mitigation remains active until including basic mitigation feedback details. Mitigation remains
the DOTS client explicitly terminates mitigation, or the mitigation active until the DOTS client explicitly terminates mitigation, or the
lifetime expires. mitigation lifetime expires.
DOTS signaling can happen with DTLS [RFC6347] over UDP and TLS DOTS signaling can happen with DTLS [RFC6347] over UDP and TLS
[RFC5246] over TCP. Likewise, DOTS requests may be sent using IPv4 [RFC5246] over TCP. Likewise, DOTS requests may be sent using IPv4
or IPv6 transfer capabilities. A Happy Eyeballs procedure for DOTS or IPv6 transfer capabilities. A Happy Eyeballs procedure for DOTS
signal channel is specified in Section 4.3. signal channel is specified in Section 4.3.
Messages exchanged between DOTS agents are serialized using Concise Messages exchanged between DOTS agents are serialized using Concise
Binary Object Representation (CBOR) [RFC7049], CBOR is a binary Binary Object Representation (CBOR) [RFC7049], CBOR is a binary
encoding designed for small code and message size. CBOR encoded encoding scheme designed for small code and message size. CBOR-
payloads are used to convey signal channel specific payload messages encoded payloads are used to carry signal channel-specific payload
that convey request parameters and response information such as messages which convey request parameters and response information
errors. This specification uses the encoding rules defined in such as errors. In order to allow the use of the same data models,
[I-D.ietf-core-yang-cbor] for representing mitigation scope and DOTS [RFC7951] specifies the JSON encoding of YANG-modeled data. A
signal channel session configuration data defined using YANG similar effort for CBOR is defined in [I-D.ietf-core-yang-cbor].
(Section 5) as CBOR data.
From that standpoint, this document specifies a YANG data model for
representing mitigation scopes and DOTS signal channel session
configuration data (Section 5). Representing these data as CBOR data
is assumed to follow the rules in [I-D.ietf-core-yang-cbor] or those
in [RFC7951] combined with JSON/CBOR conversion rules in [RFC7049].
In order to prevent fragmentation, DOTS agents must follow the In order to prevent fragmentation, DOTS agents must follow the
recommendations in Section 4.6 of [RFC7252]. Refer to Section 7.3 recommendations documented in Section 4.6 of [RFC7252]. Refer to
for more details. Section 7.3 for more details.
DOTS agents MUST support GET, PUT, and DELETE CoAP methods. The DOTS agents MUST support GET, PUT, and DELETE CoAP methods. The
payload included in CoAP responses with 2.xx and 3.xx Response Codes payload included in CoAP responses with 2.xx and 3.xx Response Codes
MUST be of content type "application/cbor" (Section 5.5.1 of MUST be of content type "application/cbor" (Section 5.5.1 of
[RFC7252]). CoAP responses with 4.xx and 5.xx error Response Codes [RFC7252]). CoAP responses with 4.xx and 5.xx error Response Codes
MUST include a diagnostic payload (Section 5.5.2 of [RFC7252]). The MUST include a diagnostic payload (Section 5.5.2 of [RFC7252]). The
Diagnostic Payload may contain additional information to aid Diagnostic Payload may contain additional information to aid
troubleshooting. troubleshooting.
In deployments where multiple DOTS clients are enabled in a network In deployments where multiple DOTS clients are enabled in a network
(owned by the same entity), the DOTS server may detect conflicting (owned and operated by the same entity), the DOTS server may detect
mitigation requests from these clients. This document does not aim conflicting mitigation requests from these clients. This document
to specify a comprehensive list of conditions under which a DOTS does not aim to specify a comprehensive list of conditions under
server will characterize two mitigation requests from distinct DOTS which a DOTS server will characterize two mitigation requests from
clients as conflicting, nor recommend a DOTS server behavior for distinct DOTS clients as conflicting, nor recommend a DOTS server
processing conflicting mitigation requests. Those considerations are behavior for processing conflicting mitigation requests. Those
implementation- and deployment-specific. Nevertheless, the document considerations are implementation- and deployment-specific.
specifies the mechanisms to notify DOTS clients when conflicts occur, Nevertheless, the document specifies the mechanisms to notify DOTS
including the conflict cause (Section 4.4). clients when conflicts occur, including the conflict cause
(Section 4.4).
In deployments where one or more translators (e.g., NAT44, NAT64,
NPTv6) are enabled between the client's network and the DOTS server,
DOTS signal channel messages forwarded to a DOTS server must not
include internal IP addresses/prefixes and/or port numbers; external
addresses/ prefixes and/or port numbers as assigned by the translator
must be used instead. This document does not make any recommendation
about possible translator discovery mechanisms. The following are
some (non-exhaustive) deployment examples that may be considered:
o Port Control Protocol (PCP) [RFC6887] or Session Traversal
Utilities for NAT (STUN) [RFC5389] may be used to retrieve the
external addresses/prefixes and/or port numbers. Information
retrieved by means of PCP will be used to feed the DOTS signal
channel messages that will be sent to a DOTS server.
o A DOTS gateway may be co-located with the translator. The DOTS
gateway will need to update the DOTS messages, based upon the
local translator's binding table.
4. DOTS Signal Channel: Messages & Behaviors 4. DOTS Signal Channel: Messages & Behaviors
4.1. DOTS Server(s) Discovery 4.1. DOTS Server(s) Discovery
This document assumes that DOTS clients are provisioned with the This document assumes that DOTS clients are provisioned with the
reachability information of their DOTS server(s) using a variety of reachability information of their DOTS server(s) using a variety of
means (e.g., local configuration, or dynamic means such as DHCP). means (e.g., local configuration, or dynamic means such as DHCP).
These means are out of scope of this document. These means are out of scope of this document.
Likewise, it is out of scope of this document to specify the behavior Likewise, it is out of scope of this document to specify the behavior
to follow by a DOTS client to place its requests (e.g., contact all of a DOTS client when it sends requests (e.g., contact all servers,
servers, select one server among the list) when multiple DOTS servers select one server among the list) when multiple DOTS servers are
are provisioned. provisioned.
4.2. CoAP URIs 4.2. CoAP URIs
The DOTS server MUST support the use of the path-prefix of "/.well- The DOTS server MUST support the use of the path-prefix of "/.well-
known/" as defined in [RFC5785] and the registered name of "dots". known/" as defined in [RFC5785] and the registered name of "dots".
Each DOTS operation is indicated by a path-suffix that indicates the Each DOTS operation is indicated by a path-suffix that indicates the
intended operation. The operation path (Table 1) is appended to the intended operation. The operation path (Table 1) is appended to the
path-prefix to form the URI used with a CoAP request to perform the path-prefix to form the URI used with a CoAP request to perform the
desired DOTS operation. desired DOTS operation.
skipping to change at page 8, line 40 skipping to change at page 9, line 17
+-----------------------+----------------+-------------+ +-----------------------+----------------+-------------+
| Mitigation | /v1/mitigate | Section 4.4 | | Mitigation | /v1/mitigate | Section 4.4 |
+-----------------------+----------------+-------------+ +-----------------------+----------------+-------------+
| Session configuration | /v1/config | Section 4.5 | | Session configuration | /v1/config | Section 4.5 |
+-----------------------+----------------+-------------+ +-----------------------+----------------+-------------+
Table 1: Operations and their corresponding URIs Table 1: Operations and their corresponding URIs
4.3. Happy Eyeballs for DOTS Signal Channel 4.3. Happy Eyeballs for DOTS Signal Channel
DOTS signaling can happen with DTLS over UDP and TLS over TCP. A DOTS signaling can operate with DTLS over UDP and TLS over TCP. A
DOTS client can use DNS to determine the IP address(es) of a DOTS DOTS client can use DNS to determine the IP address(es) of a DOTS
server or a DOTS client may be provided with the list of DOTS server server or a DOTS client may be provided with the list of the IP
IP addresses. The DOTS client MUST know a DOTS server's domain name; addresses of various DOTS servers. The DOTS client MUST know a DOTS
hard-coding the domain name of the DOTS server into software is NOT server's domain name; hard-coding the domain name of the DOTS server
RECOMMENDED in case the domain name is not valid or needs to change into software is NOT RECOMMENDED in case the domain name is not valid
for legal or other reasons. The DOTS client performs A and/or AAAA or needs to change for legal or other reasons. The DOTS client
record lookup of the domain name and the result will be a list of IP performs A and/or AAAA record lookup of the domain name and the
addresses, each of which can be used to contact the DOTS server using result will be a list of IP addresses, each of which can be used to
UDP and TCP. contact the DOTS server using UDP and TCP.
If an IPv4 path to reach a DOTS server is found, but the DOTS If an IPv4 path to reach a DOTS server is found, but the DOTS
server's IPv6 path is not working, a dual-stack DOTS client can server's IPv6 path is not working, a dual-stack DOTS client can
experience a significant connection delay compared to an IPv4-only experience a significant connection delay compared to an IPv4-only
DOTS client. The other problem is that if a middlebox between the DOTS client. The other problem is that if a middlebox between the
DOTS client and DOTS server is configured to block UDP, the DOTS DOTS client and DOTS server is configured to block UDP traffic, the
client will fail to establish a DTLS session with the DOTS server and DOTS client will fail to establish a DTLS session with the DOTS
will, then, have to fall back to TLS over TCP incurring significant server and , as a consequence, will have to fall back to TLS over
connection delays. [I-D.ietf-dots-requirements] discusses that DOTS TCP, thereby incurring significant connection delays.
agents will have to support both connectionless and connection- [I-D.ietf-dots-requirements] mentions that DOTS agents will have to
oriented protocols. support both connectionless and connection-oriented protocols.
To overcome these connection setup problems, the DOTS client can
attempt to connect to the DOTS server using both IPv6 and IPv4, and
try both DTLS over UDP and TLS over TCP in a manner similar to the
Happy Eyeballs mechanism [RFC6555]. These connection attempts are
performed by the DOTS client when it initializes, and the DOTS client
uses the results of the Happy Eyeballs procedure for sending its
subsequent messages to the DOTS server.
To overcome these connection setup problems, the DOTS client can try
connecting to the DOTS server using both IPv6 and IPv4, and try both
DTLS over UDP and TLS over TCP in a fashion similar to the Happy
Eyeballs mechanism [RFC6555]. These connection attempts are
performed by the DOTS client when its initializes, and the client
uses that information for its subsequent alert to the DOTS server.
In order of preference (most preferred first), it is UDP over IPv6, In order of preference (most preferred first), it is UDP over IPv6,
UDP over IPv4, TCP over IPv6, and finally TCP over IPv4, which UDP over IPv4, TCP over IPv6, and finally TCP over IPv4, which
adheres to address preference order [RFC6724] and the DOTS preference adheres to address preference order [RFC6724] and the DOTS
that UDP be used over TCP (to avoid TCP's head of line blocking). preference, which privileges the use of UDP over TCP (to avoid TCP's
head of line blocking).
DOTS client DOTS server DOTS client DOTS server
| | | |
|--DTLS ClientHello, IPv6 ---->X | |--DTLS ClientHello, IPv6 ---->X |
|--TCP SYN, IPv6-------------->X | |--TCP SYN, IPv6-------------->X |
|--DTLS ClientHello, IPv4 ---->X | |--DTLS ClientHello, IPv4 ---->X |
|--TCP SYN, IPv4----------------------------------------->| |--TCP SYN, IPv4----------------------------------------->|
|--DTLS ClientHello, IPv6 ---->X | |--DTLS ClientHello, IPv6 ---->X |
|--TCP SYN, IPv6-------------->X | |--TCP SYN, IPv6-------------->X |
|<-TCP SYNACK---------------------------------------------| |<-TCP SYNACK---------------------------------------------|
skipping to change at page 9, line 48 skipping to change at page 10, line 29
Figure 4: DOTS Happy Eyeballs Figure 4: DOTS Happy Eyeballs
In reference to Figure 4, the DOTS client sends two TCP SYNs and two In reference to Figure 4, the DOTS client sends two TCP SYNs and two
DTLS ClientHello messages at the same time over IPv6 and IPv4. In DTLS ClientHello messages at the same time over IPv6 and IPv4. In
this example, it is assumed that the IPv6 path is broken and UDP is this example, it is assumed that the IPv6 path is broken and UDP is
dropped by a middlebox but has little impact to the DOTS client dropped by a middlebox but has little impact to the DOTS client
because there is no long delay before using IPv4 and TCP. The DOTS because there is no long delay before using IPv4 and TCP. The DOTS
client repeats the mechanism to discover if DOTS signaling with DTLS client repeats the mechanism to discover if DOTS signaling with DTLS
over UDP becomes available from the DOTS server, so the DOTS client over UDP becomes available from the DOTS server, so the DOTS client
can migrate the DOTS signal channel from TCP to UDP, but such probing can migrate the DOTS signal channel from TCP to UDP. But such
SHOULD NOT be done more frequently than every 24 hours and MUST NOT probing SHOULD NOT be done more frequently than every 24 hours and
be done more frequently than every 5 minutes. MUST NOT be done more frequently than every 5 minutes.
4.4. DOTS Mitigation Methods 4.4. DOTS Mitigation Methods
The following methods are used by a DOTS client to request, withdraw, The following methods are used by a DOTS client to request, withdraw,
or retrieve the status of mitigation requests: or retrieve the status of mitigation requests:
PUT: DOTS clients use the PUT method to request mitigation from a PUT: DOTS clients use the PUT method to request mitigation from a
DOTS server (Section 4.4.1). During active mitigation, DOTS DOTS server (Section 4.4.1). During active mitigation, DOTS
clients may use PUT requests to convey mitigation efficacy clients may use PUT requests to carry mitigation efficacy
updates to the DOTS server (Section 4.4.3). updates to the DOTS server (Section 4.4.3).
GET: DOTS clients may use the GET method to subscribe to DOTS GET: DOTS clients may use the GET method to subscribe to DOTS
server status messages, or to retrieve the list of its server status messages, or to retrieve the list of its
mitigations maintained by a DOTS server (Section 4.4.2). mitigations maintained by a DOTS server (Section 4.4.2).
DELETE: DOTS clients use the DELETE method to withdraw a request for DELETE: DOTS clients use the DELETE method to withdraw a request for
mitigation from a DOTS server (Section 4.4.4). mitigation from a DOTS server (Section 4.4.4).
Mitigation request and response messages are marked as Non- Mitigation request and response messages are marked as Non-
confirmable messages (Section 2.2 of [RFC7252]). confirmable messages (Section 2.2 of [RFC7252]).
DOTS agents SHOULD follow the data transmission guidelines discussed DOTS agents SHOULD follow the data transmission guidelines discussed
in Section 3.1.3 of [RFC8085] and control transmission behavior by in Section 3.1.3 of [RFC8085] and control transmission behavior by
not sending on average more than one UDP datagram per RTT to the peer not sending more than one UDP datagram per RTT to the peer DOTS agent
DOTS agent. on average.
Requests marked by the DOTS client as Non-confirmable messages are Requests marked by the DOTS client as Non-confirmable messages are
sent at regular intervals until a response is received from the DOTS sent at regular intervals until a response is received from the DOTS
server. If the DOTS client cannot maintain an RTT estimate, it server. If the DOTS client cannot maintain an RTT estimate, it
SHOULD NOT send more than one Non-confirmable request every 3 SHOULD NOT send more than one Non-confirmable request every 3
seconds, and SHOULD use an even less aggressive rate when possible seconds, and SHOULD use an even less aggressive rate whenever
(case 2 in Section 3.1.3 of [RFC8085]). possible (case 2 in Section 3.1.3 of [RFC8085]).
4.4.1. Request Mitigation 4.4.1. Request Mitigation
When a DOTS client requires mitigation for any reason, the DOTS When a DOTS client requires mitigation for some reason, the DOTS
client uses CoAP PUT method to send a mitigation request to its DOTS client uses the CoAP PUT method to send a mitigation request to its
server(s) (Figure 5, illustrated in JSON diagnostic notation). If DOTS server(s) (Figure 5, illustrated in JSON diagnostic notation).
this DOTS client is entitled to solicit the DOTS service, the DOTS If this DOTS client is entitled to solicit the DOTS service, the DOTS
server can enable mitigation on behalf of the DOTS client by server can enable mitigation on behalf of the DOTS client by
communicating the DOTS client's request to the mitigator and relaying communicating the DOTS client's request to the mitigator and relaying
selected mitigator feedback to the requesting DOTS client. selected mitigator feedback to the requesting DOTS client.
Header: PUT (Code=0.03) Header: PUT (Code=0.03)
Uri-Host: "host" Uri-Host: "host"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "version" Uri-Path: "version"
Uri-Path: "mitigate" Uri-Path: "mitigate"
Content-Type: "application/cbor" Content-Type: "application/cbor"
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
"string" "string"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": integer, "mitigation-id": integer,
"target-ip": [
"string"
],
"target-prefix": [ "target-prefix": [
"string" "string"
], ],
"target-port-range": [ "target-port-range": [
{ {
"lower-port": integer, "lower-port": integer,
"upper-port": integer "upper-port": integer
} }
], ],
"target-protocol": [ "target-protocol": [
skipping to change at page 11, line 50 skipping to change at page 12, line 47
], ],
"alias-name": [ "alias-name": [
"string" "string"
], ],
"lifetime": integer "lifetime": integer
} }
] ]
} }
} }
Figure 5: PUT to convey DOTS signals Figure 5: PUT to convey DOTS mitigation requests
The parameters are described below: The parameters are described below:
client-identifier: The client identifier MAY be conveyed by the DOTS client-identifier: The client identifier MAY be conveyed by the DOTS
gateway to propagate the DOTS client identity from the gateway's gateway to propagate the DOTS client identity from the gateway's
client-side to the gateway's server-side, and from the gateway's client-side to the gateway's server-side, and from the gateway's
server-side to the DOTS server. This allows the final DOTS server server-side to the DOTS server. This allows the DOTS server to
to accept mitigation requests with scopes which the DOTS client is accept mitigation requests with scopes which the DOTS client is
authorized to manage. authorized to manage.
The 'client-identifier' value MUST be assigned by the DOTS gateway The 'client-identifier' value MUST be assigned by the DOTS gateway
in a manner that ensures that there is no probability that the in a manner that ensures that there is zero probability that the
same value will be assigned to a different DOTS client. The DOTS same value will be assigned to a different DOTS client. The DOTS
gateway MUST obscure potentially sensitive DOTS client identity gateway MUST conceal potentially sensitive DOTS client identity
information. The client-identifier attribute SHOULD NOT to be information. The client-identifier attribute SHOULD NOT be
generated and included by the DOTS client. generated and included by the DOTS client.
This is an optional attribute. This is an optional attribute.
mitigation-id: Identifier for the mitigation request represented mitigation-id: Identifier for the mitigation request represented
using an integer. This identifier MUST be unique for each with an integer. This identifier MUST be unique for each
mitigation request bound to the DOTS client, i.e., the mitigation- mitigation request bound to the DOTS client, i.e., the mitigation-
id parameter value in the mitigation request needs to be unique id parameter value in the mitigation request needs to be unique
relative to the mitigation-id parameter values of active relative to the mitigation-id parameter values of active
mitigation requests conveyed from the DOTS client to the DOTS mitigation requests conveyed from the DOTS client to the DOTS
server. This identifier MUST be generated by the DOTS client. server. This identifier MUST be generated by the DOTS client.
This document does not make any assumption about how this This document does not make any assumption about how this
identifier is generated. identifier is generated.
This is a mandatory attribute. This is a mandatory attribute.
target-ip: A list of IP addresses identifying resources under
attack. This is an optional attribute.
target-prefix: A list of prefixes identifying resources under target-prefix: A list of prefixes identifying resources under
attack. Prefixes are represented using Classless Inter-domain attack. Prefixes are represented using Classless Inter-Domain
Routing (CIDR) notation [RFC4632]. Routing (CIDR) notation [RFC4632].
As a reminder, the prefix length must be less than or equal to 32
(resp. 128) for IPv4 (resp. IPv6).
This is an optional attribute. This is an optional attribute.
target-port-range: A list of port numbers bound to resources under target-port-range: A list of port numbers bound to resources under
attack. attack.
The port range is defined by two bounds, a lower port number The port range is defined by two bounds, a lower port number
(lower-port) and an upper port number (upper-port). When only (lower-port) and an upper port number (upper-port). When only
'lower-port' is present, it represents a single port number. For 'lower-port' is present, it represents a single port number. For
TCP, UDP, Stream Control Transmission Protocol (SCTP) [RFC4960], TCP, UDP, Stream Control Transmission Protocol (SCTP) [RFC4960],
skipping to change at page 14, line 18 skipping to change at page 15, line 12
This is a mandatory attribute. This is a mandatory attribute.
Because of the complexity to handle partial failure cases, this Because of the complexity to handle partial failure cases, this
specification does not allow for including multiple mitigation specification does not allow for including multiple mitigation
requests in the same PUT request. Concretely, a DOTS client MUST NOT requests in the same PUT request. Concretely, a DOTS client MUST NOT
include multiple 'scope' parameters in the same PUT request. include multiple 'scope' parameters in the same PUT request.
The CBOR key values for the parameters are defined in Section 6. The CBOR key values for the parameters are defined in Section 6.
Section 9 defines how the CBOR key values can be allocated to Section 9 defines how the CBOR key values can be allocated to
standards bodies and vendors. standard bodies and vendors.
FQDN and URI mitigation scopes may be thought of as a form of scope FQDN and URI mitigation scopes may be thought of as a form of scope
alias, in which the addresses to which the domain name or URI resolve alias, in which the addresses to which the domain name or URI resolve
represent the full scope of the mitigation. represent the full scope of the mitigation.
In the PUT request at least one of the attributes 'target-ip' or In the PUT request at least one of the attributes 'target-prefix' or
'target-prefix' or 'target-fqdn' or 'target-uri 'or 'alias-name' MUST 'target-fqdn' or 'target-uri 'or 'alias-name' MUST be present. If
be present. If the attribute value is empty, then the attribute MUST the attribute value is empty, then the attribute MUST NOT be present
NOT be present in the request. in the request.
The relative order of two mitigation requests from a DOTS client is The relative order of two mitigation requests from a DOTS client is
determined by comparing their respective 'mitigation-id' values. If determined by comparing their respective 'mitigation-id' values. If
two mitigation requests have overlapping mitigation scopes, the two mitigation requests have overlapping mitigation scopes, the
mitigation request with higher numeric 'mitigation-id' value will mitigation request with the highest numeric 'mitigation-id' value
override the mitigation request with a lower numeric 'mitigation-id' will override the other mitigation request. Two mitigation-ids from
value. Two mitigation-ids from a DOTS client are overlapping if a DOTS client are overlapping if there is a common IP address, IP
there is a common IP address, IP prefix, FQDN, URI, or alias-name. prefix, FQDN, URI, or alias-name. To avoid maintaining a long list
To avoid maintaining a long list of overlapping mitigation requests of overlapping mitigation requests from a DOTS client and avoid
from a DOTS client and avoid error-prone provisioning of mitigation error-prone provisioning of mitigation requests from a DOTS client,
requests from a DOTS client, the overlapped lower numeric the overlapped lower numeric 'mitigation-id' MUST be automatically
'mitigation-id' MUST be automatically deleted and no longer available deleted and no longer available at the DOTS server.
at the DOTS server.
The Uri-Path option carries a major and minor version nomenclature to The Uri-Path option carries a major and minor version nomenclature to
manage versioning and DOTS signal channel in this specification uses manage versioning and DOTS signal channel in this specification uses
v1 major version. v1 major version.
Figure 6 shows a PUT request example to signal that ports 80, 8080, Figure 6 shows a PUT request example to signal that ports 80, 8080,
and 443 on the servers 2001:db8:6401::1 and 2001:db8:6401::2 are and 443 used by 2001:db8:6401::1 and 2001:db8:6401::2 servers are
being attacked (illustrated in JSON diagnostic notation). under attack (illustrated in JSON diagnostic notation).
Header: PUT (Code=0.03) Header: PUT (Code=0.03)
Uri-Host: "www.example.com" Uri-Host: "www.example.com"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "v1" Uri-Path: "v1"
Uri-Path: "mitigate" Uri-Path: "mitigate"
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
"dz6pHjaADkaFTbjr0JGBpw" "dz6pHjaADkaFTbjr0JGBpw"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": 12332, "mitigation-id": 12332,
"target-ip": [ "target-prefix": [
"2001:db8:6401::1", "2001:db8:6401::1/128",
"2001:db8:6401::2" "2001:db8:6401::2/128"
], ],
"target-port-range": [ "target-port-range": [
{ {
"lower-port": 80 "lower-port": 80
}, },
{ {
"lower-port": 443 "lower-port": 443
}, },
{ {
"lower-port": 8080 "lower-port": 8080
skipping to change at page 16, line 19 skipping to change at page 17, line 19
81 # array(1) 81 # array(1)
76 # text(22) 76 # text(22)
647A3670486A6141446B614654626A72304A47427077 # "dz6pHjaADkaFTbjr0JGBpw" 647A3670486A6141446B614654626A72304A47427077 # "dz6pHjaADkaFTbjr0JGBpw"
02 # unsigned(2) 02 # unsigned(2)
81 # array(1) 81 # array(1)
A4 # map(4) A4 # map(4)
03 # unsigned(3) 03 # unsigned(3)
19 302C # unsigned(12332) 19 302C # unsigned(12332)
04 # unsigned(4) 04 # unsigned(4)
82 # array(2) 82 # array(2)
70 # text(16) 74 # text(20)
323030313A6462383A363430313A3A31 # "2001:db8:6401::1" 323030313A6462383A363430313A3A312F313238 # "2001:db8:6401::1/128"
70 # text(16) 74 # text(20)
323030313A6462383A363430313A3A32 # "2001:db8:6401::2" 323030313A6462383A363430313A3A322F313238 # "2001:db8:6401::2/128"
05 # unsigned(5) 05 # unsigned(5)
83 # array(3) 83 # array(3)
A1 # map(1) A1 # map(1)
06 # unsigned(6) 06 # unsigned(6)
18 50 # unsigned(80) 18 50 # unsigned(80)
A1 # map(1) A1 # map(1)
06 # unsigned(6) 06 # unsigned(6)
19 01BB # unsigned(443) 19 01BB # unsigned(443)
A1 # map(1) A1 # map(1)
06 # unsigned(6) 06 # unsigned(6)
skipping to change at page 16, line 45 skipping to change at page 17, line 45
81 # array(1) 81 # array(1)
06 # unsigned(6) 06 # unsigned(6)
Figure 7: PUT for DOTS signal (CBOR) Figure 7: PUT for DOTS signal (CBOR)
If the DOTS client is using the certificate provisioned by the If the DOTS client is using the certificate provisioned by the
Enrollment over Secure Transport (EST) server [RFC7030] in the DOTS Enrollment over Secure Transport (EST) server [RFC7030] in the DOTS
gateway-domain to authenticate itself to the DOTS gateway, then the gateway-domain to authenticate itself to the DOTS gateway, then the
'client-identifier' value can be the output of a cryptographic hash 'client-identifier' value can be the output of a cryptographic hash
algorithm whose input is the DER-encoded ASN.1 representation of the algorithm whose input is the DER-encoded ASN.1 representation of the
Subject Public Key Info (SPKI) of an X.509 certificate. In this Subject Public Key Info (SPKI) of an X.509 certificate.
version of the specification, the cryptographic hash algorithm used
is SHA-256 [RFC6234]. The output of the cryptographic hash algorithm In this version of the specification, the cryptographic hash
is truncated to 16 bytes; truncation is done by stripping off the algorithm used is SHA-256 [RFC6234]. The output of the cryptographic
final 16 bytes. The truncated output is base64url encoded. If the hash algorithm is truncated to 16 bytes; truncation is done by
'client-identifier' value is already present in the mitigation stripping off the final 16 bytes. The truncated output is base64url
request received from the DOTS client, the DOTS gateway MAY compute encoded. If the 'client-identifier' value is already present in the
the 'client-identifier' value, as discussed above, and add the mitigation request received from the DOTS client, the DOTS gateway
computed 'client-identifier' value to the end of the 'client- MAY compute the 'client-identifier' value, as discussed above, and
add the computed 'client-identifier' value to the end of the 'client-
identifier' list. The DOTS server MUST NOT use the 'client- identifier' list. The DOTS server MUST NOT use the 'client-
identifier' for the DOTS client authentication process. identifier' for the DOTS client authentication process.
In both DOTS signal and data channel sessions, the DOTS client MUST In both DOTS signal and data channel sessions, the DOTS client MUST
authenticate itself to the DOTS server (Section 8). The DOTS server authenticate itself to the DOTS server (Section 8). The DOTS server
may use the algorithm in Section 7 of [RFC7589] to derive the DOTS may use the algorithm presented in Section 7 of [RFC7589] to derive
client identity or username from the client certificate. The DOTS the DOTS client identity or username from the client certificate.
client identity allows the DOTS server to accept mitigation requests The DOTS client identity allows the DOTS server to accept mitigation
with scopes which the DOTS client is authorized to manage. The DOTS requests with scopes that the DOTS client is authorized to manage.
server couples the DOTS signal and data channel sessions using the The DOTS server couples the DOTS signal and data channel sessions
DOTS client identity and the 'client-identifier' parameter value, so using the DOTS client identity and the 'client-identifier' parameter
the DOTS server can validate whether the aliases conveyed in the value, so the DOTS server can validate whether the aliases conveyed
mitigation request were indeed created by the same DOTS client using in the mitigation request were indeed created by the same DOTS client
the DOTS data channel session. If the aliases were not created by using the DOTS data channel session. If the aliases were not created
the DOTS client, the DOTS server returns 4.00 (Bad Request) in the by the DOTS client, the DOTS server returns 4.00 (Bad Request) in the
response. response.
The DOTS server couples the DOTS signal channel sessions using the The DOTS server couples the DOTS signal channel sessions using the
DOTS client identity and the 'client-identifier' parameter value, and DOTS client identity and the 'client-identifier' parameter value, and
the DOTS server uses 'mitigation-id' parameter value to detect the DOTS server uses 'mitigation-id' parameter value to detect
duplicate mitigation requests. If the mitigation request contains duplicate mitigation requests. If the mitigation request contains
both alias-name and other parameters identifying the target resources the alias-name and other parameters identifying the target resources
(such as, 'target-ip', 'target-prefix', 'target-port-range', 'target- (such as, 'target-prefix', 'target-port-range', 'target-fqdn', or
fqdn', or 'target-uri'), then the DOTS server appends the parameter 'target-uri'), then the DOTS server appends the parameter values in
values in 'alias-name' with the corresponding parameter values in 'alias-name' with the corresponding parameter values in 'target-
'target-ip', 'target-prefix', 'target-port-range', 'target-fqdn', or prefix', 'target-port-range', 'target-fqdn', or 'target-uri'.
'target-uri'.
The DOTS server indicates the result of processing the PUT request The DOTS server indicates the result of processing the PUT request
using CoAP response codes. CoAP 2.xx codes are success. CoAP 4.xx using CoAP response codes. CoAP 2.xx codes are success. CoAP 4.xx
codes are some sort of invalid requests (client errors). COAP 5.xx codes are some sort of invalid requests (client errors). COAP 5.xx
codes are returned if the DOTS server has erred or is currently codes are returned if the DOTS server has erred or is currently
unavailable to provide mitigation in response to the mitigation unavailable to provide mitigation in response to the mitigation
request from the DOTS client. request from the DOTS client.
Figure 8 shows an example of a PUT request that is successfully Figure 8 shows an example of a PUT request that is successfully
processed (i.e., CoAP 2.xx response codes). processed (i.e., CoAP 2.xx response codes).
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
"string" "string"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": integer, "mitigation-id": 12332,
"lifetime": integer "lifetime": 3600
} }
] ]
} }
} }
Figure 8: 2.xx response body Figure 8: 2.xx response body
If the request is missing one or more mandatory attributes, includes If the request is missing one or more mandatory attributes, or
multiple 'scope' parameters, or contains invalid or unknown includes multiple 'scope' parameters, or contains invalid or unknown
parameters, the DOTS server replies with 4.00 (Bad Request). DOTS parameters, the DOTS server replies with 4.00 (Bad Request). DOTS
agents can safely ignore Vendor-Specific parameters they don't agents can safely ignore Vendor-Specific parameters they don't
understand. understand.
A DOTS server that receives a mitigation request with a lifetime set A DOTS server that receives a mitigation request with a lifetime set
to 0 MUST reply with a 4.00 (Bad Request). to '0' MUST reply with a 4.00 (Bad Request).
If the DOTS server does not find the 'mitigation-id' parameter value If the DOTS server does not find the 'mitigation-id' parameter value
conveyed in the PUT request in its configuration data, it MAY accept conveyed in the PUT request in its configuration data, it MAY accept
the mitigation request by sending back a 2.01 (Created) response to the mitigation request by sending back a 2.01 (Created) response to
the DOTS client; the DOTS server will consequently try to mitigate the DOTS client; the DOTS server will consequently try to mitigate
the attack. the attack.
If the DOTS server finds the 'mitigation-id' parameter value conveyed If the DOTS server finds the 'mitigation-id' parameter value conveyed
in the PUT request in its configuration data, it MAY update the in the PUT request in its configuration data, it MAY update the
mitigation request, and a 2.04 (Changed) response is returned to mitigation request, and a 2.04 (Changed) response is returned to
skipping to change at page 19, line 14 skipping to change at page 20, line 14
as sent in the original mitigation request apart from a possible as sent in the original mitigation request apart from a possible
change to the lifetime parameter value. change to the lifetime parameter value.
A DOTS gateway MUST update the 'client-identifier' list in the A DOTS gateway MUST update the 'client-identifier' list in the
response to remove the 'client-identifier' value it had added in the response to remove the 'client-identifier' value it had added in the
corresponding request before forwarding the response to the DOTS corresponding request before forwarding the response to the DOTS
client. client.
4.4.2. Retrieve Information Related to a Mitigation 4.4.2. Retrieve Information Related to a Mitigation
A GET request is used to retrieve information (including status) of a A GET request is used by a DOTS client to retrieve information
DOTS mitigation from a DOTS server. If the DOTS server does not find (including status) of DOTS mitigations from a DOTS server.
the 'mitigation-id' parameter value conveyed in the GET request in
its configuration data, it responds with a 4.04 (Not Found) error The same considerations for manipulating 'client-identifier'
response code. parameter by a DOTS gateway specified in Section 4.4.1 MUST be
followed for GET requests.
If the DOTS server does not find the 'mitigation-id' parameter value
conveyed in the GET request in its configuration data for the
requesting DOTS client or the one identified by 'client-identifier',
it MUST respond with a 4.04 (Not Found) error response code.
Likewise, the same error MUST be returned as a response to a request
to retrieve all mitigation records of a given DOTS client if the DOTS
server does not find any mitigation record for that DOTS client or
the one identified by 'client-identifier'.
The 'c' (content) parameter and its permitted values defined in The 'c' (content) parameter and its permitted values defined in
[I-D.ietf-core-comi] can be used to retrieve non-configuration data [I-D.ietf-core-comi] can be used to retrieve non-configuration data
(attack mitigation status) or configuration data or both. The DOTS (attack mitigation status) or configuration data or both. The DOTS
server SHOULD support this optional filtering capability but can server may support this optional filtering capability. It can safely
safely ignore it if not supported. ignore it if not supported.
The following examples illustrate how a DOTS client retrieves active The following examples illustrate how a DOTS client retrieves active
mitigation requests from a DOTS server. In particular: mitigation requests from a DOTS server. In particular:
o Figure 9 shows the example of a GET request to retrieve all DOTS o Figure 9 shows the example of a GET request to retrieve all DOTS
mitigation requests signaled by a DOTS client. mitigation requests signaled by a DOTS client.
o Figure 10 shows the example of a GET request to retrieve a o Figure 10 shows the example of a GET request to retrieve a
specific DOTS mitigation request signaled by a DOTS client. The specific DOTS mitigation request signaled by a DOTS client. The
configuration data to be reported in the response is formatted in configuration data to be reported in the response is formatted in
the same order it was processed at the DOTS server. the same order it was processed by the DOTS server.
These two examples assume the default of "c=a"; that is the DOTS These two examples assume the default of "c=a"; that is, the DOTS
client asks for all data to be reported by the DOTS server. client asks for all data to be reported by the DOTS server.
Header: GET (Code=0.01) Header: GET (Code=0.01)
Uri-Host: "host" Uri-Host: "host"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "version" Uri-Path: "version"
Uri-Path: "mitigate" Uri-Path: "mitigate"
Observe : 0 Observe : 0
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
"string" "dz6pHjaADkaFTbjr0JGBpw"
] ]
} }
} }
Figure 9: GET to retrieve all DOTS mitigation requests Figure 9: GET to retrieve all DOTS mitigation requests
Header: GET (Code=0.01) Header: GET (Code=0.01)
Uri-Host: "host" Uri-Host: "host"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "version" Uri-Path: "version"
Uri-Path: "mitigate" Uri-Path: "mitigate"
Observe : 0 Observe : 0
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
"string" "dz6pHjaADkaFTbjr0JGBpw"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": integer "mitigation-id": 12332
} }
] ]
} }
} }
Figure 10: GET to retrieve a specific DOTS mitigation request Figure 10: GET to retrieve a specific DOTS mitigation request
Figure 11 shows a response example of all active mitigation requests Figure 11 shows a response example of all active mitigation requests
associated with the DOTS client on the DOTS server and the mitigation associated with the DOTS client on the DOTS server and the mitigation
status of each mitigation request. status of each mitigation request.
{ {
"mitigation-scope": { "mitigation-scope": {
"scope": [ "scope": [
{ {
"mitigation-id": 12332, "mitigation-id": 12332,
"mitigation-start": 1507818434.00, "mitigation-start": 1507818434.00,
"target-protocol": [ "target-protocol": [
17 17
], ],
"lifetime":1800, "lifetime": 1800,
"status":2, "status": 2,
"bytes-dropped": 134334555, "bytes-dropped": 134334555,
"bps-dropped": 43344, "bps-dropped": 43344,
"pkts-dropped": 333334444, "pkts-dropped": 333334444,
"pps-dropped": 432432 "pps-dropped": 432432
}, },
{ {
"mitigation-id": 12333, "mitigation-id": 12333,
"mitigation-start": 1507818393.00, "mitigation-start": 1507818393.00,
"target-protocol": [ "target-protocol": [
6 6
], ],
"lifetime":1800, "lifetime": 1800,
"status":3 "status": 3,
"bytes-dropped": 0, "bytes-dropped": 0,
"bps-dropped": 0, "bps-dropped": 0,
"pkts-dropped": 0, "pkts-dropped": 0,
"pps-dropped": 0 "pps-dropped": 0
} }
] ]
} }
} }
Figure 11: Response body Figure 11: Response body
The mitigation status parameters are described below: The mitigation status parameters are described below:
mitigation-start: Mitigation start time is represented in seconds mitigation-start: Mitigation start time is expressed in seconds
relative to 1970-01-01T00:00Z in UTC time (Section 2.4.1 of relative to 1970-01-01T00:00Z in UTC time (Section 2.4.1 of
[RFC7049]). The encoding is modified so that the leading tag 1 [RFC7049]). The encoding is modified so that the leading tag 1
(epoch-based date/time) MUST be omitted. (epoch-based date/time) MUST be omitted.
This is a mandatory attribute.
lifetime: The remaining lifetime of the mitigation request, in lifetime: The remaining lifetime of the mitigation request, in
seconds. seconds.
status: Status of attack mitigation. The 'status' parameter is a This is a mandatory attribute.
mandatory attribute. The various possible values of 'status'
parameter are explained in Table 2. status: Status of attack mitigation. The various possible values of
'status' parameter are explained in Table 2.
This is a mandatory attribute.
conflict-information: Indicates that a mitigation request is conflict-information: Indicates that a mitigation request is
conflicting with another mitigation request(s) from other DOTS conflicting with another mitigation request(s) from other DOTS
client(s). This optional attribute has the following structure: client(s). This optional attribute has the following structure:
conflict-status: Indicates the status of a conflicting mitigation conflict-status: Indicates the status of a conflicting mitigation
request. The following values are defined: request. The following values are defined:
1: DOTS server has detected conflicting mitigation requests 1: DOTS server has detected conflicting mitigation requests
from different DOTS clients. This mitigation request is from different DOTS clients. This mitigation request is
skipping to change at page 22, line 40 skipping to change at page 23, line 45
2: Conflicts with an existing white list. This code is 2: Conflicts with an existing white list. This code is
returned when the DDoS mitigation detects source addresses/ returned when the DDoS mitigation detects source addresses/
prefixes in the white-listed ACLs are attacking the target. prefixes in the white-listed ACLs are attacking the target.
conflict-scope Indicates the conflict scope. It may include a conflict-scope Indicates the conflict scope. It may include a
list of IP addresses, a list of prefixes, a list of port list of IP addresses, a list of prefixes, a list of port
numbers, a list of target protocols, a list of FQDNs, a list of numbers, a list of target protocols, a list of FQDNs, a list of
URIs, a list of alias-names, or references to conflicting ACLs. URIs, a list of alias-names, or references to conflicting ACLs.
retry-timer Indicates, in seconds, the time upon which the DOTS retry-timer Indicates, in seconds, the time after which the DOTS
client may re-issue the same request. The DOTS server returns client may re-issue the same request. The DOTS server returns
'retry-timer' only to DOTS client(s) for which a mitigation 'retry-timer' only to DOTS client(s) for which a mitigation
request is deactivated. Any retransmission of the same request is deactivated. Any retransmission of the same
mitigation request before the expiry of this timer is likely to mitigation request before the expiry of this timer is likely to
be rejected by the DOTS server for the same reasons. be rejected by the DOTS server for the same reasons.
The retry-timer SHOULD be equal to the lifetime of the active The retry-timer SHOULD be equal to the lifetime of the active
mitigation request resulting in the deactivation of the mitigation request resulting in the deactivation of the
conflicting mitigation request. The lifetime of the conflicting mitigation request. The lifetime of the
deactivated mitigation request will be updated to (retry-timer deactivated mitigation request will be updated to (retry-timer
skipping to change at page 23, line 10 skipping to change at page 24, line 16
mitigation request resulting in the deactivation of the mitigation request resulting in the deactivation of the
conflicting mitigation request. The lifetime of the conflicting mitigation request. The lifetime of the
deactivated mitigation request will be updated to (retry-timer deactivated mitigation request will be updated to (retry-timer
+ 45 seconds), so the DOTS client can refresh the deactivated + 45 seconds), so the DOTS client can refresh the deactivated
mitigation request after retry-timer seconds before expiry of mitigation request after retry-timer seconds before expiry of
lifetime and check if the conflict is resolved. lifetime and check if the conflict is resolved.
bytes-dropped: The total dropped byte count for the mitigation bytes-dropped: The total dropped byte count for the mitigation
request since the attack mitigation is triggered. The count wraps request since the attack mitigation is triggered. The count wraps
around when it reaches the maximum value of unsigned integer. around when it reaches the maximum value of unsigned integer.
This is an optional attribute. This is an optional attribute.
bps-dropped: The average dropped bytes per second for the mitigation bps-dropped: The average number of dropped bytes per second for the
request since the attack mitigation is triggered. This SHOULD be mitigation request since the attack mitigation is triggered. This
a five-minute average. This is an optional attribute. SHOULD be a five-minute average.
pkts-dropped: The total dropped packet count for the mitigation This is an optional attribute.
request since the attack mitigation is triggered. This is an
optional attribute.
pps-dropped: The average dropped packets per second for the pkts-dropped: The total number of dropped packet count for the
mitigation request since the attack mitigation is triggered. This mitigation request since the attack mitigation is triggered.
SHOULD be a five-minute average. This is an optional attribute.
This is an optional attribute.
pps-dropped: The average number of dropped packets per second for
the mitigation request since the attack mitigation is triggered.
This SHOULD be a five-minute average.
This is an optional attribute.
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| Parameter | Description | | Parameter | Description |
| value | | | value | |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 1 | Attack mitigation is in progress (e.g., changing the | | 1 | Attack mitigation is in progress (e.g., changing the |
| | network path to re-route the inbound traffic to DOTS | | | network path to re-route the inbound traffic to DOTS |
| | mitigator). | | | mitigator). |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 2 | Attack is successfully mitigated (e.g., traffic is | | 2 | Attack is successfully mitigated (e.g., traffic is |
skipping to change at page 24, line 37 skipping to change at page 25, line 37
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 7 | Attack mitigation is withdrawn. | | 7 | Attack mitigation is withdrawn. |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 8 | Attack mitigation is rejected. | | 8 | Attack mitigation is rejected. |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
Table 2: Values of 'status' parameter Table 2: Values of 'status' parameter
The observe option defined in [RFC7641] extends the CoAP core The observe option defined in [RFC7641] extends the CoAP core
protocol with a mechanism for a CoAP client to "observe" a resource protocol with a mechanism for a CoAP client to "observe" a resource
on a CoAP server: the client retrieves a representation of the on a CoAP server: The client retrieves a representation of the
resource and requests this representation be updated by the server as resource and requests this representation be updated by the server as
long as the client is interested in the resource. A DOTS client long as the client is interested in the resource. A DOTS client
conveys the observe option set to '0' in the GET request to receive conveys the observe option set to '0' in the GET request to receive
unsolicited notifications of attack mitigation status from the DOTS unsolicited notifications of attack mitigation status from the DOTS
server. Unidirectional notifications within the bidirectional signal server.
channel allows unsolicited message delivery, enabling asynchronous
Unidirectional notifications within the bidirectional signal channel
allows unsolicited message delivery, enabling asynchronous
notifications between the agents. Due to the higher likelihood of notifications between the agents. Due to the higher likelihood of
packet loss during a DDoS attack, DOTS server periodically sends packet loss during a DDoS attack, DOTS server periodically sends
attack mitigation status to the DOTS client and also notifies the attack mitigation status to the DOTS client and also notifies the
DOTS client whenever the status of the attack mitigation changes. If DOTS client whenever the status of the attack mitigation changes. If
the DOTS server cannot maintain a RTT estimate, it SHOULD NOT send the DOTS server cannot maintain a RTT estimate, it SHOULD NOT send
more than one unsolicited notification every 3 seconds, and SHOULD more than one unsolicited notification every 3 seconds, and SHOULD
use an even less aggressive rate when possible (case 2 in use an even less aggressive rate whenever possible (case 2 in
Section 3.1.3 of [RFC8085]). Section 3.1.3 of [RFC8085]).
When conflicting requests are detected, the DOTS server enforces the When conflicting requests are detected, the DOTS server enforces the
corresponding policy (e.g. accept all requests, reject all requests, corresponding policy (e.g., accept all requests, reject all requests,
accept only one request but reject all the others, ...). It is accept only one request but reject all the others, ...). It is
assumed that this policy is supplied by the DOTS server administrator assumed that this policy is supplied by the DOTS server administrator
or it is a default behavior of the DOTS server implementation. Then, or it is a default behavior of the DOTS server implementation. Then,
the DOTS server sends notification message(s) to the DOTS client(s) the DOTS server sends notification message(s) to the DOTS client(s)
at the origin of the conflict. A conflict notification message at the origin of the conflict. A conflict notification message
includes information about the conflict cause, scope, and the status includes information about the conflict cause, scope, and the status
of the mitigation request(s). For example, of the mitigation request(s). For example,
o A notification message with status code set to '8 (Attack o A notification message with status code set to '8 (Attack
mitigation is rejected)' and 'conflict-status' set to '1' is sent mitigation is rejected)' and 'conflict-status' set to '1' is sent
to a DOTS client to indicate that this mitigation request is to a DOTS client to indicate that this mitigation request is
rejected because a conflict is detected. rejected because a conflict is detected.
o A notification message with status code set to '7 (Attack o A notification message with status code set to '7 (Attack
mitigation is withdrawn)' and 'conflict-status' set to '1' is sent mitigation is withdrawn)' and 'conflict-status' set to '1' is sent
to a DOTS client to indicate that an active mitigation request is to a DOTS client to indicate that an active mitigation request is
deactivated because a conflict is detected. deactivated because a conflict is detected.
o A notification message with status code set to '1 (Attack o A notification message with status code set to '1 (Attack
mitigation is in progress)' and 'conflict-status' set to 2 is sent mitigation is in progress)' and 'conflict-status' set to '2' is
to a DOTS client to indicate that this mitigation request is in sent to a DOTS client to indicate that this mitigation request is
progress, but a conflict is detected. in progress, but a conflict is detected.
Upon receipt of a conflict notification message indicating that a Upon receipt of a conflict notification message indicating that a
mitigation request is deactivated because of a conflict, a DOTS mitigation request is deactivated because of a conflict, a DOTS
client MUST NOT resend the same mitigation request before the expiry client MUST NOT resend the same mitigation request before the expiry
of 'retry-timer'. It is also recommended that DOTS clients support of 'retry-timer'. It is also recommended that DOTS clients support
means to alert administrators about mitigation conflicts. means to alert administrators about mitigation conflicts.
A DOTS client that is no longer interested in receiving notifications A DOTS client that is no longer interested in receiving notifications
from the DOTS server can simply "forget" the observation. When the from the DOTS server can simply "forget" the observation. When the
DOTS server then sends the next notification, the DOTS client will DOTS server sends the next notification, the DOTS client will not
not recognize the token in the message and thus will return a Reset recognize the token in the message and thus will return a Reset
message. This causes the DOTS server to remove the associated entry. message. This causes the DOTS server to remove the associated entry.
Alternatively, the DOTS client can explicitly deregister by issuing a Alternatively, the DOTS client can explicitly deregister itself by
GET request that has the Token field set to the token of the issuing a GET request that has the Token field set to the token of
observation to be cancelled and includes an Observe Option with the the observation to be cancelled and includes an Observe Option with
value set to '1' (deregister). the value set to '1' (deregister).
Figure 12 shows an example of a DOTS client requesting a DOTS server Figure 12 shows an example of a DOTS client requesting a DOTS server
to send notifications related a given mitigation request. to send notifications related to a given mitigation request.
DOTS Client DOTS Server DOTS Client DOTS Server
| | | |
| GET /<mitigation-id number> | | GET /<mitigation-id number> |
| Token: 0x4a | Registration | Token: 0x4a | Registration
| Observe: 0 | | Observe: 0 |
+------------------------------>| +------------------------------>|
| | | |
| 2.05 Content | | 2.05 Content |
| Token: 0x4a | Notification of | Token: 0x4a | Notification of
skipping to change at page 26, line 45 skipping to change at page 27, line 45
The DOTS client can send the GET request at frequent intervals The DOTS client can send the GET request at frequent intervals
without the Observe option to retrieve the configuration data of the without the Observe option to retrieve the configuration data of the
mitigation request and non-configuration data (i.e., the attack mitigation request and non-configuration data (i.e., the attack
status). The frequency of polling the DOTS server to get the status). The frequency of polling the DOTS server to get the
mitigation status should follow the transmission guidelines given in mitigation status should follow the transmission guidelines given in
Section 3.1.3 of [RFC8085]. If the DOTS server has been able to Section 3.1.3 of [RFC8085]. If the DOTS server has been able to
mitigate the attack and the attack has stopped, the DOTS server mitigate the attack and the attack has stopped, the DOTS server
indicates as such in the status, and the DOTS client recalls the indicates as such in the status, and the DOTS client recalls the
mitigation request by issuing a DELETE request for the mitigation-id. mitigation request by issuing a DELETE request for the mitigation-id.
A DOTS client SHOULD react to the status of the attack from the DOTS A DOTS client SHOULD react to the status of the attack as per the
server and not the fact that it has recognized, using its own means, information sent by the DOTS server rather than acknowledging by
that the attack has been mitigated. This ensures that the DOTS itself, using its own means, that the attack has been mitigated.
client does not recall a mitigation request in a premature fashion This ensures that the DOTS client does not recall a mitigation
because it is possible that the DOTS client does not sense the DDOS request prematurely because it is possible that the DOTS client does
attack on its resources but the DOTS server could be actively not sense the DDOS attack on its resources but the DOTS server could
mitigating the attack and the attack is not completely averted. be actively mitigating the attack and the attack is not completely
averted.
4.4.3. Efficacy Update from DOTS Clients 4.4.3. Efficacy Update from DOTS Clients
While DDoS mitigation is active, due to the likelihood of packet While DDoS mitigation is active, due to the likelihood of packet
loss, a DOTS client MAY periodically transmit DOTS mitigation loss, a DOTS client MAY periodically transmit DOTS mitigation
efficacy updates to the relevant DOTS server. A PUT request is used efficacy updates to the relevant DOTS server. A PUT request is used
to convey the mitigation efficacy update to the DOTS server. to convey the mitigation efficacy update to the DOTS server.
The PUT request MUST include all the parameters used in the PUT The PUT request MUST include all the parameters used in the PUT
request to convey the DOTS signal (Section 4.4.1) unchanged apart request to carry the DOTS signal (Section 4.4.1) unchanged apart from
from the lifetime parameter value. If this is not the case, the DOTS the lifetime parameter value. If this is not the case, the DOTS
server MUST reject the request with a 4.00 (Bad Request). server MUST reject the request with a 4.00 (Bad Request).
The If-Match Option (Section 5.10.8.1 of [RFC7252]) with an empty The If-Match Option (Section 5.10.8.1 of [RFC7252]) with an empty
value is used to make the PUT request conditional on the current value is used to make the PUT request conditional on the current
existence of the mitigation request. If UDP is used as transport, existence of the mitigation request. If UDP is used as transport,
CoAP requests may arrive out-of-order. For example, the DOTS client CoAP requests may arrive out-of-order. For example, the DOTS client
may send a PUT request to convey an efficacy update to the DOTS may send a PUT request to convey an efficacy update to the DOTS
server followed by a DELETE request to withdraw the mitigation server followed by a DELETE request to withdraw the mitigation
request, but the DELETE request arrives at the DOTS server before the request, but the DELETE request arrives at the DOTS server before the
PUT request. To handle out-of-order delivery of requests, if an If- PUT request. To handle out-of-order delivery of requests, if an If-
skipping to change at page 28, line 21 skipping to change at page 29, line 21
Content-Format: "application/cbor" Content-Format: "application/cbor"
If-Match: If-Match:
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
"string" "string"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": integer, "mitigation-id": integer,
"target-ip": [ "target-prefix": [
"string" "string"
], ],
"target-port-range": [ "target-port-range": [
{ {
"lower-port": integer, "lower-port": integer,
"upper-port": integer "upper-port": integer
} }
], ],
"target-protocol": [ "target-protocol": [
integer integer
skipping to change at page 29, line 5 skipping to change at page 30, line 5
], ],
"lifetime": integer, "lifetime": integer,
"attack-status": integer "attack-status": integer
} }
] ]
} }
} }
Figure 13: Efficacy Update Figure 13: Efficacy Update
The 'attack-status' parameter is a mandatory attribute when doing an The 'attack-status' parameter is a mandatory attribute when
efficacy update. The various possible values contained in the performing an efficacy update. The various possible values contained
'attack-status' parameter are described in Table 3. in the 'attack-status' parameter are described in Table 3.
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| Parameter | Description | | Parameter | Description |
| value | | | value | |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 1 | The DOTS client determines that it is still under | | 1 | The DOTS client determines that it is still under |
| | attack. | | | attack. |
+-----------+-------------------------------------------------------+ +-----------+-------------------------------------------------------+
| 2 | The DOTS client determines that the attack is | | 2 | The DOTS client determines that the attack is |
| | successfully mitigated (e.g., attack traffic is not | | | successfully mitigated (e.g., attack traffic is not |
skipping to change at page 30, line 5 skipping to change at page 30, line 35
returned if the DOTS server has accepted the mitigation efficacy returned if the DOTS server has accepted the mitigation efficacy
update. The error response code 5.03 (Service Unavailable) is update. The error response code 5.03 (Service Unavailable) is
returned if the DOTS server has erred or is incapable of performing returned if the DOTS server has erred or is incapable of performing
the mitigation. the mitigation.
4.4.4. Withdraw a Mitigation 4.4.4. Withdraw a Mitigation
A DELETE request is used to withdraw a DOTS mitigation request from a A DELETE request is used to withdraw a DOTS mitigation request from a
DOTS server (Figure 14). DOTS server (Figure 14).
The same considerations for manipulating 'client-identifier'
parameter by a DOTS gateway, as specified in Section 4.4.1, MUST be
followed for DELETE requests.
Header: DELETE (Code=0.04) Header: DELETE (Code=0.04)
Uri-Host: "host" Uri-Host: "host"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "version" Uri-Path: "version"
Uri-Path: "mitigate" Uri-Path: "mitigate"
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"mitigation-scope": { "mitigation-scope": {
"client-identifier": [ "client-identifier": [
skipping to change at page 30, line 27 skipping to change at page 31, line 27
"scope": [ "scope": [
{ {
"mitigation-id": integer "mitigation-id": integer
} }
] ]
} }
} }
Figure 14: Withdraw DOTS signal Figure 14: Withdraw DOTS signal
If the request does not include a 'mitigation-id', the DOTS server If the request does not include a 'mitigation-id' parameter, the DOTS
MUST reply with a 4.00 (Bad Request). server MUST reply with a 4.00 (Bad Request).
Once the request is validated, the DOTS server immediately Once the request is validated, the DOTS server immediately
acknowledges a DOTS client's request to withdraw the DOTS signal acknowledges a DOTS client's request to withdraw the DOTS signal
using 2.02 (Deleted) response code with no response payload. A 2.02 using 2.02 (Deleted) response code with no response payload. A 2.02
(Deleted) Response Code is returned even if the 'mitigation-id' (Deleted) Response Code is returned even if the 'mitigation-id'
parameter value conveyed in the DELETE request does not exist in its parameter value conveyed in the DELETE request does not exist in its
configuration data before the request. configuration data before the request.
If the DOTS server finds the 'mitigation-id' parameter value conveyed If the DOTS server finds the 'mitigation-id' parameter value conveyed
in the DELETE request in its configuration data, then to protect in the DELETE request in its configuration data for the DOTS client,
against route or DNS flapping caused by a DOTS client rapidly then to protect against route or DNS flapping caused by a DOTS client
toggling mitigation, and to dampen the effect of oscillating attacks, rapidly removing a mitigation, and to dampen the effect of
the DOTS server MAY allow mitigation to continue for a limited period oscillating attacks, the DOTS server MAY allow mitigation to continue
after acknowledging a DOTS client's withdrawal of a mitigation for a limited period after acknowledging a DOTS client's withdrawal
request. During this period, the DOTS server status messages SHOULD of a mitigation request. During this period, the DOTS server status
indicate that mitigation is active but terminating (Section 4.4.2). messages SHOULD indicate that mitigation is active but terminating
(Section 4.4.2).
The initial active-but-terminating period SHOULD be sufficiently long The initial active-but-terminating period SHOULD be sufficiently long
to absorb latency incurred by route propagation. The active-but- to absorb latency incurred by route propagation. The active-but-
terminating period SHOULD be set by default to 120 seconds. If the terminating period SHOULD be set by default to 120 seconds. If the
client requests mitigation again before the initial active-but- client requests mitigation again before the initial active-but-
terminating period elapses, the DOTS server MAY exponentially terminating period elapses, the DOTS server MAY exponentially
increase the active-but- terminating period up to a maximum of 300 increase the active-but- terminating period up to a maximum of 300
seconds (5 minutes). seconds (5 minutes).
After the active-but-terminating period elapses, the DOTS server MUST After the active-but-terminating period elapses, the DOTS server MUST
treat the mitigation as terminated, as the DOTS client is no longer treat the mitigation as terminated, as the DOTS client is no longer
responsible for the mitigation. For example, if there is a financial responsible for the mitigation. For example, if there is a financial
relationship between the DOTS client and server domains, the DOTS relationship between the DOTS client and server domains, the DOTS
client ceases incurring cost at this point. client stops incurring cost at this point.
4.5. DOTS Signal Channel Session Configuration 4.5. DOTS Signal Channel Session Configuration
The DOTS client can negotiate, configure, and retrieve the DOTS The DOTS client can negotiate, configure, and retrieve the DOTS
signal channel session behavior. The DOTS signal channel can be signal channel session behavior. The DOTS signal channel can be
used, for example, to configure the following: used, for example, to configure the following:
a. Heartbeat interval: DOTS agents regularly send heartbeats (CoAP a. Heartbeat interval (heartbeat-interval): DOTS agents regularly
Ping/Pong) to each other after mutual authentication in order to send heartbeats (CoAP Ping/Pong) to each other after mutual
keep the DOTS signal channel open, heartbeat messages are authentication is successfully completed in order to keep the
exchanged between the DOTS agents every heartbeat-interval DOTS signal channel open. Heartbeat messages are exchanged
seconds to detect the current status of the DOTS signal channel between the DOTS agents every 'heartbeat-interval' seconds to
session. detect the current status of the DOTS signal channel session.
b. Missing heartbeats allowed: This variable indicates the maximum b. Missing heartbeats allowed (missing-hb-allowed): This variable
number of consecutive heartbeat messages for which a DOTS agent indicates the maximum number of consecutive heartbeat messages
did not receive a response before concluding that the session is for which a DOTS agent did not receive a response before
disconnected or defunct. concluding that the session is disconnected or defunct.
c. Acceptable signal loss ratio: Maximum retransmissions, c. Acceptable signal loss ratio: Maximum retransmissions,
retransmission timeout value and other message transmission retransmission timeout value, and other message transmission
parameters for the DOTS signal channel. parameters for the DOTS signal channel.
Reliability is provided to requests and responses by marking them as Requests and responses are deemed reliable by marking them as
Confirmable (CON) messages. DOTS signal channel session Confirmable (CON) messages. DOTS signal channel session
configuration requests and responses are marked as Confirmable configuration requests and responses are marked as Confirmable
messages. As explained in Section 2.1 of [RFC7252], a Confirmable messages. As explained in Section 2.1 of [RFC7252], a Confirmable
message is retransmitted using a default timeout and exponential message is retransmitted using a default timeout and exponential
back-off between retransmissions, until the DOTS server sends an back-off between retransmissions, until the DOTS server sends an
Acknowledgement message (ACK) with the same Message ID conveyed from Acknowledgement message (ACK) with the same Message ID conveyed from
the DOTS client. Message transmission parameters are defined in the DOTS client.
Section 4.8 of [RFC7252]. The DOTS server can either piggyback the
response in the acknowledgement message or if the DOTS server is not Message transmission parameters are defined in Section 4.8 of
able to respond immediately to a request carried in a Confirmable [RFC7252]. The DOTS server can either piggyback the response in the
message, it simply responds with an Empty Acknowledgement message so acknowledgement message or, if the DOTS server cannot respond
that the DOTS client can stop retransmitting the request. Empty immediately to a request carried in a Confirmable message, it simply
Acknowledgement message is explained in Section 2.2 of [RFC7252]. responds with an Empty Acknowledgement message so that the DOTS
When the response is ready, the server sends it in a new Confirmable client can stop retransmitting the request. Empty Acknowledgement
message which then in turn needs to be acknowledged by the DOTS message is explained in Section 2.2 of [RFC7252]. When the response
client (see Sections 5.2.1 and 5.2.2 of [RFC7252]). Requests and is ready, the server sends it in a new Confirmable message which in
responses exchanged between DOTS agents during peacetime are marked turn needs to be acknowledged by the DOTS client (see Sections 5.2.1
as Confirmable messages. and 5.2.2 of [RFC7252]). Requests and responses exchanged between
DOTS agents during peacetime are marked as Confirmable messages.
Implementation Note: A DOTS client that receives a response in a Implementation Note: A DOTS client that receives a response in a
CON message may want to clean up the message state right after CON message may want to clean up the message state right after
sending the ACK. If that ACK is lost and the DOTS server sending the ACK. If that ACK is lost and the DOTS server
retransmits the CON, the DOTS client may no longer have any state retransmits the CON, the DOTS client may no longer have any state
to which to correlate this response, making the retransmission an that would help it correlate this response, thereby unexpecting
unexpected message; the DOTS client will send a Reset message so the retransmission message. The DOTS client will send a Reset
it does not receive any more retransmissions. This behavior is message so it does not receive any more retransmissions. This
normal and not an indication of an error (see Section 5.3.2 of behavior is normal and not an indication of an error (see
[RFC7252] for more details). Section 5.3.2 of [RFC7252] for more details).
4.5.1. Discover Configuration Parameters 4.5.1. Discover Configuration Parameters
A GET request is used to obtain acceptable and current configuration A GET request is used to obtain acceptable (e.g., minimum and maximum
parameters on the DOTS server for DOTS signal channel session values) and current configuration parameters on the DOTS server for
configuration. Figure 15 shows how to obtain acceptable DOTS signal channel session configuration. Figure 15 shows how to
configuration parameters for the DOTS server. obtain acceptable configuration parameters for the DOTS server.
Header: GET (Code=0.01) Header: GET (Code=0.01)
Uri-Host: "host" Uri-Host: "host"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "version" Uri-Path: "version"
Uri-Path: "config" Uri-Path: "config"
Figure 15: GET to retrieve configuration Figure 15: GET to retrieve configuration
The DOTS server in the 2.05 (Content) response conveys the current, The DOTS server in the 2.05 (Content) response conveys the current,
minimum and maximum attribute values acceptable by the DOTS server. minimum, and maximum attribute values acceptable by the DOTS server
(Figure 16).
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"heartbeat-interval": { "heartbeat-interval": {
"current-value": integer, "current-value": integer,
"min-value": integer, "min-value": integer,
"max-value" : integer, "max-value": integer
}, },
"missing-hb-allowed": { "missing-hb-allowed": {
"current-value": integer, "current-value": integer,
"min-value": integer, "min-value": integer,
"max-value" : integer, "max-value": integer
}, },
"max-retransmit": { "max-retransmit": {
"current-value": integer, "current-value": integer,
"min-value": integer, "min-value": integer,
"max-value" : integer, "max-value": integer
}, },
"ack-timeout": { "ack-timeout": {
"current-value": integer, "current-value": integer,
"min-value": integer, "min-value": integer,
"max-value" : integer, "max-value": integer
}, },
"ack-random-factor": { "ack-random-factor": {
"current-value": number, "current-value": number,
"min-value": number, "min-value": number,
"max-value" : number, "max-value": number
}, },
"trigger-mitigation": { "trigger-mitigation": {
"current-value": boolean, "current-value": boolean
},
"config-interval": {
"current-value": integer,
"min-value": integer,
"max-value": integer
} }
} }
Figure 16: GET response body Figure 16: GET response body
Figure 17 shows an example of acceptable and current configuration Figure 17 shows an example of acceptable and current configuration
parameters on the DOTS server for DOTS signal channel session parameters on a DOTS server for DOTS signal channel session
configuration. configuration.
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"heartbeat-interval": { "heartbeat-interval": {
"current-value": 30, "current-value": 30,
"min-value": 15, "min-value": 15,
"max-value" : 240, "max-value": 240
}, },
"missing-hb-allowed": { "missing-hb-allowed": {
"current-value": 5, "current-value": 5,
"min-value": 3, "min-value": 3,
"max-value" : 9, "max-value": 9
}, },
"max-retransmit": { "max-retransmit": {
"current-value": 3, "current-value": 3,
"min-value": 2, "min-value": 2,
"max-value" : 15, "max-value": 15
}, },
"ack-timeout": { "ack-timeout": {
"current-value": 2, "current-value": 2,
"min-value": 1, "min-value": 1,
"max-value" : 30, "max-value": 30
}, },
"ack-random-factor": { "ack-random-factor": {
"current-value": 1.5, "current-value": 1.5,
"min-value": 1.1, "min-value": 1.1,
"max-value" : 4.0, "max-value": 4.0
}, },
"trigger-mitigation": { "trigger-mitigation": {
"current-value": true, "current-value": true
},
"config-interval": {
"current-value": 1439,
"min-value": 0,
"max-value": 65535
} }
} }
Figure 17: Configuration response body Figure 17: Configuration response body
4.5.2. Convey DOTS Signal Channel Session Configuration 4.5.2. Convey DOTS Signal Channel Session Configuration
A PUT request is used to convey the configuration parameters for the A PUT request is used to convey the configuration parameters for the
signal channel (e.g., heartbeat interval, maximum retransmissions). signal channel (e.g., heartbeat interval, maximum retransmissions).
Message transmission parameters for CoAP are defined in Section 4.8 Message transmission parameters for CoAP are defined in Section 4.8
skipping to change at page 35, line 15 skipping to change at page 36, line 21
seconds and should use longer intervals when possible. seconds and should use longer intervals when possible.
Furthermore, [RFC4787] recommends NATs to use a state timeout of 2 Furthermore, [RFC4787] recommends NATs to use a state timeout of 2
minutes or longer, but experience shows that sending packets every minutes or longer, but experience shows that sending packets every
15 to 30 seconds is necessary to prevent the majority of 15 to 30 seconds is necessary to prevent the majority of
middleboxes from losing state for UDP flows. From that middleboxes from losing state for UDP flows. From that
standpoint, this specification recommends a minimum heartbeat- standpoint, this specification recommends a minimum heartbeat-
interval of 15 seconds and a maximum heartbeat-interval of 240 interval of 15 seconds and a maximum heartbeat-interval of 240
seconds. The recommended value of 30 seconds is selected to seconds. The recommended value of 30 seconds is selected to
anticipate the expiry of NAT state. anticipate the expiry of NAT state.
A heartbeat-interval of 30 second may be seen as too chatty in A heartbeat-interval of 30 seconds may be seen as too chatty in
some deployments. For such deployments, DOTS agents may negotiate some deployments. For such deployments, DOTS agents may negotiate
longer heartbeat-interval values to avoid overloading the network longer heartbeat-interval values to prevent any network overload
with too frequent keepalives. with too frequent keepalives.
When a confirmable "CoAP Ping" is sent, and if there is no response, When a confirmable "CoAP Ping" is sent, and if there is no response,
the "CoAP Ping" is retransmitted max-retransmit number of times by the "CoAP Ping" is retransmitted max-retransmit number of times by
the CoAP layer using an initial timeout set to a random duration the CoAP layer using an initial timeout set to a random duration
between ack-timeout and (ack-timeout*ack-random-factor) and between ack-timeout and (ack-timeout*ack-random-factor) and
exponential back-off between retransmissions. By choosing the exponential back-off between retransmissions. By choosing the
recommended transmission parameters, the "CoAP Ping" will timeout recommended transmission parameters, the "CoAP Ping" will timeout
after 45 seconds. If the DOTS agent does not receive any response after 45 seconds. If the DOTS agent does not receive any response
from the peer DOTS agent for missing-hb-allowed number of consecutive from the peer DOTS agent for 'missing-hb-allowed' number of
"CoAP Ping" confirmable messages, it concludes that the DOTS signal consecutive "CoAP Ping" confirmable messages, it concludes that the
channel session is disconnected. A DOTS client MUST NOT transmit a DOTS signal channel session is disconnected. A DOTS client MUST NOT
"CoAP Ping" while waiting for the previous "CoAP Ping" response from transmit a "CoAP Ping" while waiting for the previous "CoAP Ping"
the same DOTS server. response from the same DOTS server.
If the DOTS agent wishes to change the default values of message If the DOTS agent wishes to change the default values of message
transmission parameters, then it should follow the guidance given in transmission parameters, then it should follow the guidance given in
Section 4.8.1 of [RFC7252]. The DOTS agents MUST use the negotiated Section 4.8.1 of [RFC7252]. The DOTS agents MUST use the negotiated
values for message transmission parameters and default values for values for message transmission parameters and default values for
non-negotiated message transmission parameters. non-negotiated message transmission parameters.
The signal channel session configuration is applicable to a single The signal channel session configuration is applicable to a single
DOTS signal channel session between the DOTS agents. DOTS signal channel session between the DOTS agents.
skipping to change at page 36, line 19 skipping to change at page 37, line 19
Uri-Path: "version" Uri-Path: "version"
Uri-Path: "config" Uri-Path: "config"
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"signal-config": { "signal-config": {
"session-id": integer, "session-id": integer,
"heartbeat-interval": integer, "heartbeat-interval": integer,
"missing-hb-allowed": integer, "missing-hb-allowed": integer,
"max-retransmit": integer, "max-retransmit": integer,
"ack-timeout": integer, "ack-timeout": integer,
"ack-random-factor": number "ack-random-factor": number,
"trigger-mitigation": boolean "trigger-mitigation": boolean,
"config-interval": integer
} }
} }
Figure 18: PUT to convey the DOTS signal channel session Figure 18: PUT to convey the DOTS signal channel session
configuration data. configuration data.
The parameters are described below: The parameters in Figure 18 are described below:
session-id: Identifier for the DOTS signal channel session session-id: Identifier for the DOTS signal channel session
configuration data represented as an integer. This identifier configuration data represented as an integer. This identifier
MUST be generated by the DOTS client. This document does not make MUST be generated by the DOTS client. This document does not make
any assumption about how this identifier is generated. any assumption about how this identifier is generated.
This is a mandatory attribute. This is a mandatory attribute.
heartbeat-interval: Time interval in seconds between two heartbeat-interval: Time interval in seconds between two
consecutive heartbeat messages. consecutive heartbeat messages.
'0' is used to disable the heartbeat mechanism.
This is an optional attribute. This is an optional attribute.
missing-hb-allowed: Maximum number of consecutive heartbeat missing-hb-allowed: Maximum number of consecutive heartbeat
messages for which the DOTS agent did not receive a response messages for which the DOTS agent did not receive a response
before concluding that the session is disconnected. before concluding that the session is disconnected.
This is an optional attribute. This is an optional attribute.
max-retransmit: Maximum number of retransmissions for a message max-retransmit: Maximum number of retransmissions for a message
(referred to as MAX_RETRANSMIT parameter in CoAP). (referred to as MAX_RETRANSMIT parameter in CoAP).
skipping to change at page 37, line 29 skipping to change at page 38, line 31
session is lost. Automated mitigation on loss of signal is session is lost. Automated mitigation on loss of signal is
discussed in Section 3.3.3 of [I-D.ietf-dots-architecture]. discussed in Section 3.3.3 of [I-D.ietf-dots-architecture].
If the DOTS client ceases to respond to heartbeat messages, the If the DOTS client ceases to respond to heartbeat messages, the
DOTS server can detect that the DOTS session is lost. DOTS server can detect that the DOTS session is lost.
The default value of the parameter is 'true'. The default value of the parameter is 'true'.
This is an optional attribute. This is an optional attribute.
In the PUT request at least one of the attributes 'heartbeat- config-interval: This parameter is returned to indicate the time
interval', 'missing-hb-allowed', 'max-retransmit', 'ack-timeout', interval expressed in minutes, which a DOTS agent must wait for
'ack-random-factor', and 'trigger-mitigation' MUST be present. The before re-contacting its peer in order to retrieve the signal
PUT request with higher numeric 'session-id' value over-rides the channel configuration data.
DOTS signal channel session configuration data installed by a PUT
request with a lower numeric 'session-id' value. '0' is used to disable this refresh mechanism.
If a non-null value of 'config-interval' is received by a DOTS
agent, it has to issue a PUT request to refresh the configuration
parameters for the signal channel before the expiry of 'config-
interval'.
This mechanism allows to update the configuration data if a change
occurs at the DOTS server side. For example, the new
configuration may instruct a DOTS client to cease heartbeats or
reduce heartbeat frequency.
If this parameter is not returned, this is equivalent to receiving
a 'config-interval' value set to '0'.
If a DOTS server detects that a misbehaving DOTS client does not
contact the DOTS server after the expiry of 'config-interval', in
order to retrieve the signal channel configuration data, it MAY
terminate the (D)TLS session. A (D)TLS session is terminated by
the receipt of an authenticated message that closes the connection
(e.g., a fatal alert (Section 7.2 of [RFC5246])).
This is an optional attribute.
At least one of the attributes 'heartbeat-interval', 'missing-hb-
allowed', 'max-retransmit', 'ack-timeout', 'ack-random-factor', and
'trigger-mitigation' MUST be present in the PUT request . The PUT
request with a higher numeric 'session-id' value overrides the DOTS
signal channel session configuration data installed by a PUT request
with a lower numeric 'session-id' value.
Figure 19 shows a PUT request example to convey the configuration Figure 19 shows a PUT request example to convey the configuration
parameters for the DOTS signal channel. parameters for the DOTS signal channel.
Header: PUT (Code=0.03) Header: PUT (Code=0.03)
Uri-Host: "www.example.com" Uri-Host: "www.example.com"
Uri-Path: ".well-known" Uri-Path: ".well-known"
Uri-Path: "dots" Uri-Path: "dots"
Uri-Path: "v1" Uri-Path: "v1"
Uri-Path: "config" Uri-Path: "config"
skipping to change at page 39, line 40 skipping to change at page 41, line 11
If a DOTS server wants to redirect a DOTS client to an alternative If a DOTS server wants to redirect a DOTS client to an alternative
DOTS server for a signal session, then the response code 3.00 DOTS server for a signal session, then the response code 3.00
(alternate server) will be returned in the response to the client. (alternate server) will be returned in the response to the client.
The DOTS server can return the error response code 3.00 in response The DOTS server can return the error response code 3.00 in response
to a PUT request from the DOTS client or convey the error response to a PUT request from the DOTS client or convey the error response
code 3.00 in a unidirectional notification response from the DOTS code 3.00 in a unidirectional notification response from the DOTS
server. server.
The DOTS server in the error response conveys the alternate DOTS The DOTS server in the error response conveys the alternate DOTS
server's FQDN, and the alternate DOTS server IP address(es) and time server's FQDN, and the alternate DOTS server's IP address(es) and
to live values in the CBOR body. time to live values in the CBOR body (Figure 21).
{ {
"alt-server": "string", "alt-server": "string",
"alt-server-record": [ "alt-server-record": [
{ {
"addr": "string", "addr": "string",
"ttl" : integer, "ttl" : integer
} }
] ]
} }
Figure 21: Error response body Figure 21: Error response body
The parameters are described below: The parameters are described below:
alt-server: FQDN of an alternate DOTS server. alt-server: FQDN of an alternate DOTS server.
skipping to change at page 40, line 46 skipping to change at page 42, line 6
{ {
"ttl" : 1800, "ttl" : 1800,
"addr": "2001:db8:6401::2" "addr": "2001:db8:6401::2"
} }
] ]
} }
Figure 22: Example of error response body Figure 22: Example of error response body
When the DOTS client receives 3.00 response, it considers the current When the DOTS client receives 3.00 response, it considers the current
request as having failed, but SHOULD try the request with the request as failed, but SHOULD try re-sending the request to the
alternate DOTS server. During a DDOS attack, the DNS server may be alternate DOTS server. During a DDOS attack, the DNS server may be
subjected to DDOS attack, alternate DOTS server IP addresses conveyed the target of another DDoS attack, alternate DOTS server's IP
in the 3.00 response help the DOTS client to skip DNS lookup of the addresses conveyed in the 3.00 response help the DOTS client skip DNS
alternate DOTS server and can try to establish UDP or TCP session lookup of the alternate DOTS server. The DOTS client can then try to
with the alternate DOTS server IP addresses. The DOTS client SHOULD establish a UDP or a TCP session with the alternate DOTS server. The
implement DNS64 function to handle the scenario where IPv6-only DOTS DOTS client SHOULD implement a DNS64 function to handle the scenario
client communicates with IPv4-only alternate DOTS server. where an IPv6-only DOTS client communicates with an IPv4-only
alternate DOTS server.
4.7. Heartbeat Mechanism 4.7. Heartbeat Mechanism
To provide a metric of signal health and distinguish an 'idle' signal To provide an indication of signal health and distinguish an 'idle'
channel from a 'disconnected' or 'defunct' session, the DOTS agent signal channel from a 'disconnected' or 'defunct' session, the DOTS
sends a heartbeat over the signal channel to maintain its half of the agent sends a heartbeat over the signal channel to maintain its half
channel. The DOTS agent similarly expects a heartbeat from its peer of the channel. The DOTS agent similarly expects a heartbeat from
DOTS agent, and may consider a session terminated in the extended its peer DOTS agent, and may consider a session terminated in the
absence of a peer agent heartbeat. prolonged absence of a peer agent heartbeat.
While the communication between the DOTS agents is quiescent, the While the communication between the DOTS agents is quiescent, the
DOTS client will probe the DOTS server to ensure it has maintained DOTS client will probe the DOTS server to ensure it has maintained
cryptographic state and vice versa. Such probes can also keep alive cryptographic state and vice versa. Such probes can also keep
firewall and/or NAT bindings. This probing reduces the frequency of firewall and/or NAT bindings alive. This probing reduces the
establishing a new handshake when a DOTS signal needs to be conveyed frequency of establishing a new handshake when a DOTS signal needs to
to the DOTS server. be conveyed to the DOTS server.
In case of a volumetric DDoS attack saturating the incoming link to In case of a massive DDoS attack that saturates the incoming link(s)
the DOTS client, all traffic from the DOTS server to the DOTS client to the DOTS client, all traffic from the DOTS server to the DOTS
will likely be dropped, although the DOTS server receives heartbeat client will likely be dropped, although the DOTS server receives
requests and DOTS messages from the DOTS client. In this scenario, heartbeat requests in addition to DOTS messages sent by the DOTS
the DOTS agents MUST behave differently to handle message client. In this scenario, the DOTS agents MUST behave differently to
transmission and DOTS session liveliness during link saturation: handle message transmission and DOTS session liveliness during link
saturation:
o The DOTS client MUST NOT consider the DOTS session terminated even o The DOTS client MUST NOT consider the DOTS session terminated even
after maximum 'missing-hb-allowed' threshold is reached. The DOTS after a maximum 'missing-hb-allowed' threshold is reached. The
client SHOULD continue to use the current DOTS session, and send DOTS client SHOULD keep on using the current DOTS session to send
heartbeat requests over the current DOTS session, so the DOTS heartbeat requests over it, so that the DOTS server knows the DOTS
server knows the DOTS client has not disconnected the DOTS client has not disconnected the DOTS session.
session.
After the maximum 'missing-hb-allowed' threshold is reached, the After the maximum 'missing-hb-allowed' threshold is reached, the
DOTS client SHOULD try (D)TLS session resumption. The DOTS client DOTS client SHOULD try to resume the (D)TLS session. The DOTS
SHOULD send mitigation requests over the current DOTS session, and client SHOULD send mitigation requests over the current DOTS
in parallel, try (D)TLS session resumption or 0-RTT mode in DTLS session, and in parallel, for example, try to resume the (D)TLS
1.3 to piggyback the mitigation request in the ClientHello session or use 0-RTT mode in DTLS 1.3 to piggyback the mitigation
message. request in the ClientHello message.
Once the link is no longer saturated, if traffic from the DOTS As soon as the link is no longer saturated, if traffic from the
server reaches the DOTS client over the current DOTS session, the DOTS server reaches the DOTS client over the current DOTS session,
DOTS client can stop (D)TLS session resumption or if (D)TLS the DOTS client can stop (D)TLS session resumption or if (D)TLS
session resumption is successful then disconnect the current DOTS session resumption is successful then disconnect the current DOTS
session. session.
o If the DOTS server does not receive any traffic from the peer DOTS o If the DOTS server does not receive any traffic from the peer DOTS
client, then the DOTS server sends heartbeat requests to the DOTS client, then the DOTS server sends heartbeat requests to the DOTS
client and after maximum 'missing-hb-allowed' threshold is client and after maximum 'missing-hb-allowed' threshold is
reached, the DOTS server concludes the session is disconnected. reached, the DOTS server concludes the session is disconnected.
In DOTS over UDP, heartbeat messages may be exchanged between the In DOTS over UDP, heartbeat messages MUST be exchanged between the
DOTS agents using the "COAP Ping" mechanism defined in Section 4.2 of DOTS agents using the "CoAP Ping" mechanism defined in Section 4.2 of
[RFC7252]. Concretely, the DOTS agent sends an Empty Confirmable [RFC7252]. Concretely, the DOTS agent sends an Empty Confirmable
message and the peer DOTS agent will respond by sending an Reset message and the peer DOTS agent will respond by sending a Reset
message. message.
In DOTS over TCP, heartbeat messages can be exchanged between the In DOTS over TCP, heartbeat messages MUST be exchanged between the
DOTS agents using the Ping and Pong messages specified in Section 4.4 DOTS agents using the Ping and Pong messages specified in Section 4.4
of [I-D.ietf-core-coap-tcp-tls]. That is, the DOTS agent sends a of [I-D.ietf-core-coap-tcp-tls]. That is, the DOTS agent sends a
Ping message and the peer DOTS agent would respond by sending a Ping message and the peer DOTS agent would respond by sending a
single Pong message. single Pong message.
5. DOTS Signal Channel YANG Module 5. DOTS Signal Channel YANG Module
This document defines a YANG [RFC7950] module for mitigation scope This document defines a YANG [RFC7950] module for mitigation scope
and DOTS signal channel session configuration data. and DOTS signal channel session configuration data.
skipping to change at page 43, line 12 skipping to change at page 44, line 12
(Section 5.2), which has the following tree structure. A DOTS signal (Section 5.2), which has the following tree structure. A DOTS signal
message can either be a mitigation or a configuration message. message can either be a mitigation or a configuration message.
module: ietf-dots-signal module: ietf-dots-signal
+--rw dots-signal +--rw dots-signal
+--rw (message-type)? +--rw (message-type)?
+--:(mitigation-scope) +--:(mitigation-scope)
| +--rw client-identifier* binary | +--rw client-identifier* binary
| +--rw scope* [mitigation-id] | +--rw scope* [mitigation-id]
| +--rw mitigation-id int32 | +--rw mitigation-id int32
| +--rw target-ip* inet:ip-address
| +--rw target-prefix* inet:ip-prefix | +--rw target-prefix* inet:ip-prefix
| +--rw target-port-range* [lower-port upper-port] | +--rw target-port-range* [lower-port upper-port]
| | +--rw lower-port inet:port-number | | +--rw lower-port inet:port-number
| | +--rw upper-port inet:port-number | | +--rw upper-port inet:port-number
| +--rw target-protocol* uint8 | +--rw target-protocol* uint8
| +--rw target-fqdn* inet:domain-name | +--rw target-fqdn* inet:domain-name
| +--rw target-uri* inet:uri | +--rw target-uri* inet:uri
| +--rw alias-name* string | +--rw alias-name* string
| +--rw lifetime? int32 | +--rw lifetime? int32
| +--rw mitigation-start? int64 | +--rw mitigation-start? int64
| +--ro status? enumeration | +--ro status? enumeration
| +--ro conflict-information | +--ro conflict-information
| | +--ro conflict-status? enumeration | | +--ro conflict-status? enumeration
| | +--ro conflict-cause? enumeration | | +--ro conflict-cause? enumeration
| | +--ro retry-timer? int32 | | +--ro retry-timer? int32
| | +--ro conflict-scope | | +--ro conflict-scope
| | +--ro target-ip* inet:ip-address
| | +--ro target-prefix* inet:ip-prefix | | +--ro target-prefix* inet:ip-prefix
| | +--ro target-port-range* [lower-port upper-port] | | +--ro target-port-range* [lower-port upper-port]
| | | +--ro lower-port inet:port-number | | | +--ro lower-port inet:port-number
| | | +--ro upper-port inet:port-number | | | +--ro upper-port inet:port-number
| | +--ro target-protocol* uint8 | | +--ro target-protocol* uint8
| | +--ro target-fqdn* inet:domain-name | | +--ro target-fqdn* inet:domain-name
| | +--ro target-uri* inet:uri | | +--ro target-uri* inet:uri
| | +--ro alias-name* string | | +--ro alias-name* string
| | +--ro acl-list* [name type] | | +--ro acl-list* [acl-name acl-type]
| | +--ro name -> /ietf-acl:access-lists/acl/acl-name | | +--ro acl-name -> /ietf-acl:access-lists/acl/acl-name
| | +--ro type -> /ietf-acl:access-lists/acl/acl-type | | +--ro acl-type -> /ietf-acl:access-lists/acl/acl-type
| +--ro pkts-dropped? yang:zero-based-counter64 | +--ro pkts-dropped? yang:zero-based-counter64
| +--ro bps-dropped? yang:zero-based-counter64 | +--ro bps-dropped? yang:zero-based-counter64
| +--ro bytes-dropped? yang:zero-based-counter64 | +--ro bytes-dropped? yang:zero-based-counter64
| +--ro pps-dropped? yang:zero-based-counter64 | +--ro pps-dropped? yang:zero-based-counter64
+--:(configuration) +--:(configuration)
+--rw session-id int32 +--rw session-id int32
+--rw heartbeat-interval? int16 +--rw heartbeat-interval? int16
+--rw missing-hb-allowed? int16 +--rw missing-hb-allowed? int16
+--rw max-retransmit? int16 +--rw max-retransmit? int16
+--rw ack-timeout? int16 +--rw ack-timeout? int16
+--rw ack-random-factor? decimal64 +--rw ack-random-factor? decimal64
+--rw trigger-mitigation? boolean +--rw trigger-mitigation? boolean
+--rw config-interval? int32
5.2. YANG Module 5.2. YANG Module
<CODE BEGINS> file "ietf-dots-signal@2017-12-07.yang" <CODE BEGINS> file "ietf-dots-signal@2017-12-12.yang"
module ietf-dots-signal {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-signal";
prefix "signal";
import ietf-inet-types {prefix "inet";} module ietf-dots-signal {
import ietf-yang-types {prefix yang;} yang-version 1.1;
import ietf-access-control-list {prefix "ietf-acl";} namespace "urn:ietf:params:xml:ns:yang:ietf-dots-signal";
prefix "signal";
organization "IETF DOTS Working Group"; import ietf-inet-types {prefix "inet";}
import ietf-yang-types {prefix yang;}
import ietf-access-control-list {prefix "ietf-acl";}
contact organization "IETF DDoS Open Threat Signaling (DOTS) Working Group";
"Konda, Tirumaleswar Reddy <TirumaleswarReddy_Konda@McAfee.com>
Mohamed Boucadair <mohamed.boucadair@orange.com>
Prashanth Patil <praspati@cisco.com>
Andrew Mortensen <amortensen@arbor.net>
Nik Teague <nteague@verisign.com>";
description contact
"This module contains YANG definition for the signaling "Konda, Tirumaleswar Reddy <TirumaleswarReddy_Konda@McAfee.com>
messages exchanged between the DOTS client to the DOTS server. Mohamed Boucadair <mohamed.boucadair@orange.com>
Prashanth Patil <praspati@cisco.com>
Andrew Mortensen <amortensen@arbor.net>
Nik Teague <nteague@verisign.com>";
Copyright (c) 2017 IETF Trust and the persons identified as description
authors of the code. All rights reserved. "This module contains YANG definition for the signaling
messages exchanged between a DOTS client and a DOTS server.
Redistribution and use in source and binary forms, with or Copyright (c) 2017 IETF Trust and the persons identified as
without modification, is permitted pursuant to, and subject authors of the code. All rights reserved.
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see Redistribution and use in source and binary forms, with or
the RFC itself for full legal notices."; without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
revision 2017-12-07 { This version of this YANG module is part of RFC XXXX; see
description the RFC itself for full legal notices.";
"Initial revision.";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
grouping target { revision 2017-12-12 {
description description
"Specifies the scope of the mitigation request."; "Initial revision.";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
leaf-list target-ip { grouping target {
type inet:ip-address; description
description "Specifies the scope of the mitigation request.";
"IPv4 or IPv6 address identifying the target.";
}
leaf-list target-prefix { leaf-list target-prefix {
type inet:ip-prefix; type inet:ip-prefix;
description description
"IPv4 or IPv6 prefix identifying the target."; "IPv4 or IPv6 prefix identifying the target.";
} }
list target-port-range { list target-port-range {
key "lower-port upper-port"; key "lower-port upper-port";
description description
"Port range. When only lower-port is "Port range. When only lower-port is
present, it represents a single port."; present, it represents a single port.";
leaf lower-port { leaf lower-port {
type inet:port-number; type inet:port-number;
mandatory true; mandatory true;
description "Lower port number."; description "Lower port number.";
} }
leaf upper-port { leaf upper-port {
type inet:port-number; type inet:port-number;
must ". >= ../lower-port" { must ". >= ../lower-port" {
error-message error-message
"The upper port number must be greater than "The upper port number must be greater than
or equal to lower port number."; or equal to lower port number.";
} }
description "Upper port number."; description "Upper port number.";
} }
} }
leaf-list target-protocol { leaf-list target-protocol {
type uint8; type uint8;
description description
"Identifies the target protocol number. "Identifies the target protocol number.
The value '0' means 'all protocols'. The value '0' means 'all protocols'.
Values are taken from the IANA protocol registry: Values are taken from the IANA protocol registry:
https://www.iana.org/assignments/protocol-numbers/ https://www.iana.org/assignments/protocol-numbers/
protocol-numbers.xhtml protocol-numbers.xhtml
For example, 6 for a TCP or 17 for UDP."; For example, 6 for TCP or 17 for UDP.";
} }
leaf-list target-fqdn { leaf-list target-fqdn {
type inet:domain-name; type inet:domain-name;
description "FQDN identifying the target."; description "FQDN identifying the target.";
} }
leaf-list target-uri { leaf-list target-uri {
type inet:uri; type inet:uri;
description "URI identifying the target."; description "URI identifying the target.";
} }
leaf-list alias-name { leaf-list alias-name {
type string; type string;
description "alias name"; description "alias name";
} }
} }
grouping mitigation-scope { grouping mitigation-scope {
description description
"Specifies the scope of the mitigation request."; "Specifies the scope of the mitigation request.";
leaf-list client-identifier { leaf-list client-identifier {
type binary; type binary;
description description
"The client identifier may be conveyed by "The client identifier may be conveyed by
the DOTS gateway to propagate the DOTS client the DOTS gateway to propagate the DOTS client
identity from the gateway's client-side to the identification information from the gateway's client-side to the
gateway's server-side, and from the gateway's gateway's server-side, and from the gateway's
server-side to the DOTS server. server-side to the DOTS server.
It allows the final DOTS server to accept It allows the destination DOTS server to accept
mitigation requests with scopes which the DOTS mitigation requests with scopes which the DOTS
client is authorized to manage."; client is authorized to manage.";
} }
list scope { list scope {
key mitigation-id; key mitigation-id;
description description
"The scope of the request."; "The scope of the request.";
leaf mitigation-id { leaf mitigation-id {
type int32; type int32;
description description
"Mitigation request identifier. "Mitigation request identifier.
This identifier must be unique for each mitigation This identifier must be unique for each mitigation
request bound to the DOTS client."; request bound to the DOTS client.";
} }
uses target; uses target;
leaf lifetime {
type int32;
units "seconds";
default 3600;
description
"Indicates the lifetime of the mitigation request.";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
leaf lifetime { leaf mitigation-start {
type int32; type int64;
units "seconds"; units "seconds";
default 3600; description
description "Mitigation start time is represented in seconds
"Indicates the lifetime of the mitigation request."; relative to 1970-01-01T00:00Z in UTC time.";
reference }
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
leaf mitigation-start { leaf status {
type int64; type enumeration {
units "seconds"; enum "attack-mitigation-in-progress" {
description value 1;
"Mitigation start time is represented in seconds description
relative to 1970-01-01T00:00Z in UTC time."; "Attack mitigation is in progress (e.g., changing
} the network path to re-route the inbound traffic
to DOTS mitigator).";
}
leaf status { enum "attack-successfully-mitigated" {
type enumeration { value 2;
enum "1" { description
description "Attack is successfully mitigated (e.g., traffic
"Attack mitigation is in progress (e.g., changing is redirected to a DDOS mitigator and attack
the network path to re-route the inbound traffic traffic is dropped or blackholed).";
to DOTS mitigator)."; }
}
enum "2" { enum "attack-stopped" {
description value 3;
"Attack is successfully mitigated (e.g., traffic description
is redirected to a DDOS mitigator and attack "Attack has stopped and the DOTS client can
traffic is dropped)."; withdraw the mitigation request.";
} }
enum "3" { enum "attack-exceeded-capability" {
description value 4;
"Attack has stopped and the DOTS client can description
withdraw the mitigation request."; "Attack has exceeded the mitigation provider
} capability.";
enum "4" { }
description
"Attack has exceeded the mitigation provider
capability.";
}
enum "5" { enum "dots-client-withdrawn-mitigation" {
description value 5;
"DOTS client has withdrawn the mitigation description
request and the mitigation is active but "DOTS client has withdrawn the mitigation
terminating."; request and the mitigation is active but
} terminating.";
}
enum "6" { enum "attack-mitigation-terminated" {
description value 6;
"Attack mitigation is now terminated."; description
} "Attack mitigation is now terminated.";
}
enum "7" { enum "attack-mitigation-withdrawn" {
description value 7;
"Attack mitigation is withdrawn."; description
} "Attack mitigation is withdrawn.";
}
enum "8" { enum "attack-mitigation-rejected" {
description value 8;
"Attack mitigation is rejected."; description
} "Attack mitigation is rejected.";
} }
config false; }
description config false;
"Indicates the status of a mitigation request. description
It must be included in responses, only."; "Indicates the status of a mitigation request.
} It must be included in responses only.";
}
container conflict-information { container conflict-information {
config false; config false;
description description
"Indicates that a conflict is detected. "Indicates that a conflict is detected.
Must only be used for responses."; Must only be used for responses.";
leaf conflict-status { leaf conflict-status {
type enumeration { type enumeration {
enum "1" { enum "request-inactive-other-active" {
description value 1;
"DOTS Server has detected conflicting mitigation description
requests from different DOTS clients. "DOTS Server has detected conflicting mitigation
This mitigation request is currently inactive requests from different DOTS clients.
until the conflicts are resolved. Another
mitigation request is active.";
}
enum "2" { This mitigation request is currently inactive
description until the conflicts are resolved. Another
"DOTS Server has detected conflicting mitigation mitigation request is active.";
requests from different DOTS clients. }
This mitigation request is currently active.";
}
enum "3" { enum "request-active" {
description value 2;
"DOTS Server has detected conflicting mitigation description
requests from different DOTS clients. All "DOTS Server has detected conflicting mitigation
conflicting mitigation requests are inactive."; requests from different DOTS clients.
} This mitigation request is currently active.";
} }
description
"Indicates the conflict status.
It must be included in responses, only.";
}
leaf conflict-cause { enum "all-requests-inactive" {
type enumeration { value 3;
enum "1" { description
description "DOTS Server has detected conflicting mitigation
"Overlapping targets. conflict-scope provides requests from different DOTS clients. All
more details about the exact conflict."; conflicting mitigation requests are inactive.";
} }
}
description
"Indicates the conflict status.
It must be included in responses only.";
}
enum "2" { leaf conflict-cause {
description type enumeration {
"Conflicts with an existing white list. enum "overlapping-targets" {
value 1;
description
"Overlapping targets. conflict-scope provides
more details about the exact conflict.";
}
This code is returned when the DDoS mitigation enum "conflict-with-whitelist" {
detects source addresses/prefixes in the value 2;
white-listed ACLs are attacking the target."; description
} "Conflicts with an existing white list.
This code is returned when the DDoS mitigation
detects that some of the source addresses/prefixes
listed in the white list ACLs are actually
attacking the target.";
} }
description }
"Indicates the cause of the conflict. description
It must be included in responses, only."; "Indicates the cause of the conflict.
}
leaf retry-timer { It must be included in responses only.";
type int32; }
units "seconds";
description
"The DOTS client must not re-send the
same request before the expiry of this timer.
It must be included in responses, only.";
}
container conflict-scope { leaf retry-timer {
description type int32;
"Provides more information about the conflict scope."; units "seconds";
description
"The DOTS client must not re-send the
same request before the expiry of this timer.
It must be included in responses, only.";
}
uses target { container conflict-scope {
when "../conflict-cause = '1'"; description
} "Provides more information about the conflict scope.";
list acl-list { uses target {
when "../../conflict-cause = '2'"; when "../conflict-cause = 'overlapping-targets'";
key "name type"; }
description
"List of conflicting ACLs";
leaf name { list acl-list {
type leafref { when "../../conflict-cause = 'conflict-with-whitelist'";
path "/ietf-acl:access-lists/ietf-acl:acl" + key "acl-name acl-type";
"/ietf-acl:acl-name"; description
} "List of conflicting ACLs";
description
"Reference to the conflicting ACL name bound to
a DOTS client.";
}
leaf type { leaf acl-name {
type leafref { type leafref {
path "/ietf-acl:access-lists/ietf-acl:acl" + path "/ietf-acl:access-lists/ietf-acl:acl" +
"/ietf-acl:acl-type"; "/ietf-acl:acl-name";
} }
description description
"Reference to the conflicting ACL type bound to "Reference to the conflicting ACL name bound to
a DOTS client."; a DOTS client.";
} }
}
}
}
leaf pkts-dropped { leaf acl-type {
type yang:zero-based-counter64; type leafref {
config false; path "/ietf-acl:access-lists/ietf-acl:acl" +
description "/ietf-acl:acl-type";
"Number of dropped packets"; }
} description
leaf bps-dropped { "Reference to the conflicting ACL type bound to
type yang:zero-based-counter64; a DOTS client.";
config false; }
description }
"The average dropped bytes per second for }
the mitigation request since the attack }
mitigation is triggered."; leaf pkts-dropped {
} type yang:zero-based-counter64;
config false;
description
"Number of dropped packets";
}
leaf bytes-dropped { leaf bps-dropped {
type yang:zero-based-counter64; type yang:zero-based-counter64;
units 'bytes'; config false;
config false; description
description "The average number of dropped bytes per second for
"Counter for dropped packets; in bytes."; the mitigation request since the attack
} mitigation is triggered.";
}
leaf pps-dropped { leaf bytes-dropped {
type yang:zero-based-counter64; type yang:zero-based-counter64;
config false; units 'bytes';
description config false;
"The average dropped packets per second description
for the mitigation request since the attack "Counter for dropped packets; in bytes.";
mitigation is triggered."; }
}
}
}
grouping signal-config { leaf pps-dropped {
description type yang:zero-based-counter64;
"DOTS signal channel session configuration."; config false;
description
"The average number of dropped packets per second
for the mitigation request since the attack
mitigation is triggered.";
}
}
}
leaf session-id { grouping signal-config {
type int32; description
mandatory true; "DOTS signal channel session configuration.";
description
"An identifier for the DOTS signal channel
session configuration data.";
}
leaf heartbeat-interval { leaf session-id {
type int16; type int32;
units "seconds"; mandatory true;
default 30; description
description "An identifier for the DOTS signal channel
"DOTS agents regularly send heartbeats to each other session configuration data.";
after mutual authentication in order to keep }
the DOTS signal channel open.";
reference leaf heartbeat-interval {
"RFC XXXX: Distributed Denial-of-Service Open Threat type int16;
Signaling (DOTS) Signal Channel"; units "seconds";
} default 30;
description
"DOTS agents regularly send heartbeats to each other
after mutual authentication is successfully
completed, in order to keep the DOTS signal channel
open.
leaf missing-hb-allowed { '0' means that heartbeat mechanism is deactivated.";
type int16; reference
default 5; "RFC XXXX: Distributed Denial-of-Service Open Threat
description Signaling (DOTS) Signal Channel";
"Maximum number of missing heartbeats allowed."; }
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
leaf max-retransmit { leaf missing-hb-allowed {
type int16; type int16;
default 3; default 5;
description description
"Maximum number of retransmissions of a "Maximum number of missing heartbeats allowed.";
Confirmable message."; reference
reference "RFC XXXX: Distributed Denial-of-Service Open Threat
"RFC XXXX: Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal Channel";
Signaling (DOTS) Signal Channel"; }
}
leaf ack-timeout { leaf max-retransmit {
type int16; type int16;
units "seconds"; default 3;
default 2; description
description "Maximum number of retransmissions of a
"Initial retransmission timeout value."; Confirmable message.";
reference reference
"Section 4.8 of RFC 7552."; "RFC XXXX: Distributed Denial-of-Service Open Threat
} Signaling (DOTS) Signal Channel";
}
leaf ack-random-factor { leaf ack-timeout {
type decimal64 { type int16;
fraction-digits 2; units "seconds";
} default 2;
default 1.5; description
description "Initial retransmission timeout value.";
"Random factor used to influence the timing of reference
retransmissions."; "Section 4.8 of RFC 7552.";
reference }
"Section 4.8 of RFC 7552.";
}
leaf trigger-mitigation {
type boolean;
default true;
description
"If false, then mitigation is triggered
only when the DOTS server channel session is lost";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
}
container dots-signal { leaf ack-random-factor {
description type decimal64 {
"Main contaner for DOTS signal message. fraction-digits 2;
A DOTS signal message can be a mitigation messages or }
a configuration message."; default 1.5;
description
"Random factor used to influence the timing of
retransmissions.";
reference
"Section 4.8 of RFC 7552.";
}
choice message-type { leaf trigger-mitigation {
description type boolean;
"Either a mitigation or a configuration message."; default true;
description
"If false, then mitigation is triggered
only when the DOTS server channel session is lost";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
case mitigation-scope { leaf config-interval {
description type int32;
"Mitigation scope of a mitigation message."; units "minutes";
uses mitigation-scope; description
} "This parameter is returned by a DOTS server to
a requesting DOTS client to indicate the time interval
after which the DOTS client must contact the DOTS
server in order to retrieve the signal channel
configuration data.
case configuration { This mechanism allows the update of the configuration
description data if a change occurs.
"Configuration message.";
uses signal-config; For example, the new configuration may instruct
} a DOTS client to cease heartbeats or reduce
} heartbeat frequency.
}
} '0' is used to disable this refresh mechanism.";
<CODE ENDS> }
}
container dots-signal {
description
"Main container for DOTS signal message.
A DOTS signal message can be a mitigation message or
a configuration message.";
choice message-type {
description
"Either a mitigation or a configuration message.";
case mitigation-scope {
description
"Mitigation scope of a mitigation message.";
uses mitigation-scope;
}
case configuration {
description
"Configuration message.";
uses signal-config;
}
}
}
}
<CODE ENDS>
6. Mapping Parameters to CBOR 6. Mapping Parameters to CBOR
All parameters in the payload in the DOTS signal channel MUST be All parameters in the payload of the DOTS signal channel MUST be
mapped to CBOR types as shown in Table 4 and are given an integer key mapped to CBOR types as shown in Table 4 and are assigned an integer
to save space. The recipient of the payload MAY reject the key to save space. The recipient of the payload MAY reject the
information if it is not suitably mapped. information if it is not suitably mapped.
/----------------------+----------------+--------------------------\ /----------------------+----------------+--------------------------\
| Parameter name | CBOR key | CBOR major type of value | | Parameter name | CBOR key | CBOR major type of value |
+----------------------+----------------+--------------------------+ +----------------------+----------------+--------------------------+
| mitigation-scope | 1 | 5 (map) | | mitigation-scope | 1 | 5 (map) |
| scope | 2 | 5 (map) | | scope | 2 | 5 (map) |
| mitigation-id | 3 | 0 (unsigned) | | mitigation-id | 3 | 0 (unsigned) |
| target-ip | 4 | 4 (array) | | acl-list | 4 | 4 |
| target-port-range | 5 | 4 | | target-port-range | 5 | 4 |
| lower-port | 6 | 0 | | lower-port | 6 | 0 |
| upper-port | 7 | 0 | | upper-port | 7 | 0 |
| target-protocol | 8 | 4 | | target-protocol | 8 | 4 |
| target-fqdn | 9 | 4 | | target-fqdn | 9 | 4 |
| target-uri | 10 | 4 | | target-uri | 10 | 4 |
| alias-name | 11 | 4 | | alias-name | 11 | 4 |
| lifetime | 12 | 0 | | lifetime | 12 | 0 |
| attack-status | 13 | 0 | | attack-status | 13 | 0 |
| signal-config | 14 | 5 | | signal-config | 14 | 5 |
skipping to change at page 54, line 49 skipping to change at page 56, line 27
| missing-hb-allowed | 32 | 0 | | missing-hb-allowed | 32 | 0 |
| current-value | 33 | 0 | | current-value | 33 | 0 |
| mitigation-start | 34 | 7 (floating-point) | | mitigation-start | 34 | 7 (floating-point) |
| target-prefix | 35 | 4 (array) | | target-prefix | 35 | 4 (array) |
| client-identifier | 36 | 2 (byte string) | | client-identifier | 36 | 2 (byte string) |
| alt-server | 37 | 2 | | alt-server | 37 | 2 |
| alt-server-record | 38 | 4 | | alt-server-record | 38 | 4 |
| addr | 39 | 2 | | addr | 39 | 2 |
| ttl | 40 | 0 | | ttl | 40 | 0 |
| conflict-scope | 41 | 5 (map) | | conflict-scope | 41 | 5 (map) |
| acl-name | 42 | 2 |
| acl-type | 43 | 3 |
| config-interval | 44 | 0 |
\----------------------+----------------+--------------------------/ \----------------------+----------------+--------------------------/
Table 4: CBOR mappings used in DOTS signal channel message Table 4: CBOR mappings used in DOTS signal channel message
7. (D)TLS Protocol Profile and Performance Considerations 7. (D)TLS Protocol Profile and Performance Considerations
7.1. (D)TLS Protocol Profile 7.1. (D)TLS Protocol Profile
This section defines the (D)TLS protocol profile of DOTS signal This section defines the (D)TLS protocol profile of DOTS signal
channel over (D)TLS and DOTS data channel over TLS. channel over (D)TLS and DOTS data channel over TLS.
There are known attacks on (D)TLS, such as machine-in-the-middle and There are known attacks on (D)TLS, such as man-in-the-middle and
protocol downgrade. These are general attacks on (D)TLS and not protocol downgrade attacks. These are general attacks on (D)TLS and,
specific to DOTS over (D)TLS; please refer to the (D)TLS RFCs for as such, they are not specific to DOTS over (D)TLS; please refer to
discussion of these security issues. DOTS agents MUST adhere to the the (D)TLS RFCs for discussion of these security issues. DOTS agents
(D)TLS implementation recommendations and security considerations of MUST adhere to the (D)TLS implementation recommendations and security
[RFC7525] except with respect to (D)TLS version. Since encryption of considerations of [RFC7525] except with respect to (D)TLS version.
DOTS using (D)TLS is virtually a green-field deployment DOTS agents Since DOTS encryption that relies upon (D)TLS is virtually a green-
MUST implement only (D)TLS 1.2 or later. field deployment, DOTS agents MUST implement only (D)TLS 1.2 or
later.
When a DOTS client is configured with a domain name of the DOTS When a DOTS client is configured with a domain name of the DOTS
server, and connects to its configured DOTS server, the server may server, and connects to its configured DOTS server, the server may
present it with a PKIX certificate. In order to ensure proper present it with a PKIX certificate. In order to ensure proper
authentication, DOTS client MUST verify the entire certification path authentication, a DOTS client MUST verify the entire certification
per [RFC5280]. The DOTS client additionally uses [RFC6125] path per [RFC5280]. The DOTS client additionally uses [RFC6125]
validation techniques to compare the domain name to the certificate validation techniques to compare the domain name with the certificate
provided. provided.
A key challenge to deploying DOTS is provisioning DOTS clients, A key challenge to deploying DOTS is the provisioning of DOTS
including the distribution of keying material to DOTS clients to make clients, including the distribution of keying material to DOTS
possible the required mutual authentication of DOTS agents. EST clients to enable the required mutual authentication of DOTS agents.
defines a method of certificate enrollment by which domains operating EST defines a method of certificate enrollment by which domains
DOTS servers may provision DOTS clients with all necessary operating DOTS servers may provide DOTS clients with all the
cryptographic keying material, including a private key and necessary cryptographic keying material, including a private key and
certificate with which to authenticate itself. One deployment option a certificate to authenticate themselves. One deployment option is
is DOTS clients to behave as EST clients for certificate enrollment DOTS clients behave as EST clients for certificate enrollment from an
from an EST server provisioned by the mitigation provider. This EST server provisioned by the mitigation provider. This document
document does not specify which EST mechanism the DOTS client uses to does not specify which EST mechanism the DOTS client uses to achieve
achieve initial enrollment. initial enrollment.
Implementations compliant with this profile MUST implement all of the Implementations compliant with this profile MUST implement all of the
following items: following items:
o DTLS record replay detection (Section 3.3 of [RFC6347]) to protect o DTLS record replay detection (Section 3.3 of [RFC6347]) to protect
against replay attacks. against replay attacks.
o (D)TLS session resumption without server-side state [RFC5077] to o (D)TLS session resumption without server-side state [RFC5077] to
resume session and convey the DOTS signal. resume session and convey the DOTS signal.
o Raw public keys [RFC7250] or PSK handshake [RFC4279] which reduce o Raw public keys [RFC7250] or PSK handshake [RFC4279] which reduces
the size of the ServerHello, and can be used by DOTS agents that the size of the ServerHello, and can be used by DOTS agents that
cannot obtain certificates (e.g., DOTS clients and DOTS gateways cannot obtain certificates.
on private networks).
Implementations compliant with this profile SHOULD implement all of Implementations compliant with this profile SHOULD implement all of
the following items to reduce the delay required to deliver a DOTS the following items to reduce the delay required to deliver a DOTS
signal: signal:
o TLS False Start [RFC7918] which reduces round-trips by allowing o TLS False Start [RFC7918] which reduces round-trips by allowing
the TLS second flight of messages (ChangeCipherSpec) to also the TLS second flight of messages (ChangeCipherSpec) to also
contain the DOTS signal. contain the DOTS signal.
o Cached Information Extension [RFC7924] which avoids transmitting o Cached Information Extension [RFC7924] which avoids transmitting
the server's certificate and certificate chain if the client has the server's certificate and certificate chain if the client has
cached that information from a previous TLS handshake. cached that information from a previous TLS handshake.
o TCP Fast Open [RFC7413] can reduce the number of round-trips to o TCP Fast Open [RFC7413] can reduce the number of round-trips to
convey DOTS signal. convey DOTS signal.
7.2. (D)TLS 1.3 Considerations 7.2. (D)TLS 1.3 Considerations
TLS 1.3 [I-D.ietf-tls-tls13] provides critical latency improvements TLS 1.3 [I-D.ietf-tls-tls13] provides critical latency improvements
for connection establishment over TLS 1.2. The DTLS 1.3 protocol for connection establishment over TLS 1.2. The DTLS 1.3 protocol
[I-D.ietf-tls-dtls13] is based on the TLS 1.3 protocol and provides [I-D.ietf-tls-dtls13] is based upon the TLS 1.3 protocol and provides
equivalent security guarantees. (D)TLS 1.3 provides two basic equivalent security guarantees. (D)TLS 1.3 provides two basic
handshake modes of interest to DOTS signal channel: handshake modes the DOTS signal channel can take advantage of:
o Absent packet loss, a full handshake in which the DOTS client is o A full handshake mode in which a DOTS client can send a DOTS
able to send the DOTS signal message after one round trip and the mitigation request message after one round trip. This assumes no
DOTS server immediately after receiving the first DOTS signal packet loss is expereienced,
message from the client.
o 0-RTT mode in which the DOTS client can authenticate itself and o 0-RTT mode in which the DOTS client can authenticate itself and
send DOTS signal message on its first flight, thus reducing send DOTS mitigation request messages in the first message, thus
handshake latency. 0-RTT only works if the DOTS client has reducing handshake latency. 0-RTT only works if the DOTS client
previously communicated with that DOTS server, which is very has previously communicated with that DOTS server, which is very
likely with the DOTS signal channel. likely with the DOTS signal channel.
The DOTS client SHOULD establish a (D)TLS session with the DOTS The DOTS client has to establish a (D)TLS session with the DOTS
server during peacetime and share a PSK. server during peacetime and share a PSK.
During DDOS attack, the DOTS client can use the (D)TLS session to During a DDoS attack, the DOTS client can use the (D)TLS session
convey the DOTS signal message and if there is no response from to convey the DOTS mitigation request message and, if there is no
the server after multiple re-tries, then the DOTS client can response from the server after multiple retries, the DOTS client
resume the (D)TLS session in 0-RTT mode using PSK. can resume the (D)TLS session in 0-RTT mode using PSK.
A simplified TLS 1.3 handshake with 0-RTT DOTS signal message Section 8 of [I-D.ietf-tls-tls13] discusses some mechanisms to
exchange is shown in Figure 23. implement to limit the impact of replay attacks on 0-RTT data. If
TLS1.3 is used, DOTS servers must implement one of these
mechanisms.
A simplified TLS 1.3 handshake with 0-RTT DOTS mitigation request
message exchange is shown in Figure 23.
DOTS Client DOTS Server DOTS Client DOTS Server
ClientHello ClientHello
(Finished) (Finished)
(0-RTT DOTS signal message) (0-RTT DOTS signal message)
(end_of_early_data) --------> (end_of_early_data) -------->
ServerHello ServerHello
{EncryptedExtensions} {EncryptedExtensions}
{ServerConfiguration} {ServerConfiguration}
skipping to change at page 57, line 26 skipping to change at page 59, line 26
{Finished} {Finished}
<-------- [DOTS signal message] <-------- [DOTS signal message]
{Finished} --------> {Finished} -------->
[DOTS signal message] <-------> [DOTS signal message] [DOTS signal message] <-------> [DOTS signal message]
Figure 23: TLS 1.3 handshake with 0-RTT Figure 23: TLS 1.3 handshake with 0-RTT
7.3. MTU and Fragmentation 7.3. MTU and Fragmentation
To avoid DOTS signal message fragmentation and the consequently To avoid DOTS signal message fragmentation and the subsequent
decreased probability of message delivery, DOTS agents MUST ensure decreased probability of message delivery, DOTS agents MUST ensure
that the DTLS record MUST fit within a single datagram. If the path that the DTLS record MUST fit within a single datagram. If the path
MTU is not known to the DOTS server, an IP MTU of 1280 bytes SHOULD MTU is not known to the DOTS server, an IP MTU of 1280 bytes SHOULD
be assumed. The length of the URL MUST NOT exceed 256 bytes. If UDP be assumed. The length of the URL MUST NOT exceed 256 bytes. If UDP
is used to convey the DOTS signal messages then the DOTS client must is used to convey the DOTS signal messages then the DOTS client must
consider the amount of record expansion expected by the DTLS consider the amount of record expansion expected by the DTLS
processing when calculating the size of CoAP message that fits within processing when calculating the size of CoAP message that fits within
the path MTU. Path MTU MUST be greater than or equal to [CoAP the path MTU. Path MTU MUST be greater than or equal to [CoAP
message size + DTLS overhead of 13 octets + authentication overhead message size + DTLS overhead of 13 octets + authentication overhead
of the negotiated DTLS cipher suite + block padding (Section 4.1.1.1 of the negotiated DTLS cipher suite + block padding (Section 4.1.1.1
of [RFC6347]). If the request size exceeds the path MTU then the of [RFC6347]). If the request size exceeds the path MTU then the
DOTS client MUST split the DOTS signal into separate messages, for DOTS client MUST split the DOTS signal into separate messages, for
example the list of addresses in the 'target-ip' parameter could be example the list of addresses in the 'target-prefix' parameter could
split into multiple lists and each list conveyed in a new PUT be split into multiple lists and each list conveyed in a new PUT
request. request.
Implementation Note: DOTS choice of message size parameters works Implementation Note: DOTS choice of message size parameters works
well with IPv6 and with most of today's IPv4 paths. However, with well with IPv6 and with most of today's IPv4 paths. However, with
IPv4, it is harder to absolutely ensure that there is no IP IPv4, it is harder to reliably ensure that there is no IP
fragmentation. If IPv4 support on unusual networks is a fragmentation. If IPv4 path MTU is unknown, implementations may want
consideration and path MTU is unknown, implementations may want to to limit themselves to more conservative IPv4 datagram sizes such as
limit themselves to more conservative IPv4 datagram sizes such as 576 576 bytes, as per [RFC0791]. IP packets whose size does not exceed
bytes, as per [RFC0791] IP packets up to 576 bytes should never need 576 bytes should never need to be fragmented: therefore, sending a
to be fragmented, thus sending a maximum of 500 bytes of DOTS signal maximum of 500 bytes of DOTS signal over a UDP datagram will
over a UDP datagram will generally avoid IP fragmentation. generally avoid IP fragmentation.
8. Mutual Authentication of DOTS Agents & Authorization of DOTS Clients 8. Mutual Authentication of DOTS Agents & Authorization of DOTS Clients
(D)TLS based on client certificate can be used for mutual (D)TLS based upon client certificate can be used for mutual
authentication between DOTS agents. If a DOTS gateway is involved, authentication between DOTS agents. If a DOTS gateway is involved,
DOTS clients and DOTS gateway MUST perform mutual authentication; DOTS clients and DOTS gateways MUST perform mutual authentication;
only authorized DOTS clients are allowed to send DOTS signals to a only authorized DOTS clients are allowed to send DOTS signals to a
DOTS gateway. DOTS gateway and DOTS server MUST perform mutual DOTS gateway. The DOTS gateway and the DOTS server MUST perform
authentication; DOTS server only allows DOTS signals from authorized mutual authentication; a DOTS server only allows DOTS signals from an
DOTS gateway, creating a two-link chain of transitive authentication authorized DOTS gateway, thereby creating a two-link chain of
between the DOTS client and the DOTS server. transitive authentication between the DOTS client and the DOTS
server.
+-----------------------------------------------+ +-----------------------------------------------+
| example.com domain +---------+ | | example.com domain +---------+ |
| | AAA | | | | AAA | |
| +---------------+ | Server | | | +---------------+ | Server | |
| | Application | +------+--+ | | | Application | +------+--+ |
| | server +<-----------------+ ^ | | | server +<-----------------+ ^ |
| | (DOTS client) | | | | | | (DOTS client) | | | |
| +---------------+ | | | | +---------------+ | | |
| V V | example.net domain | V V | example.net domain
skipping to change at page 58, line 45 skipping to change at page 60, line 46
| | (DOTS client) +<---------------+ | | | (DOTS client) +<---------------+ |
| +----------------+ | | +----------------+ |
+-----------------------------------------------+ +-----------------------------------------------+
Figure 24: Example of Authentication and Authorization of DOTS Agents Figure 24: Example of Authentication and Authorization of DOTS Agents
In the example depicted in Figure 24, the DOTS gateway and DOTS In the example depicted in Figure 24, the DOTS gateway and DOTS
clients within the 'example.com' domain mutually authenticate with clients within the 'example.com' domain mutually authenticate with
each other. After the DOTS gateway validates the identity of a DOTS each other. After the DOTS gateway validates the identity of a DOTS
client, it communicates with the AAA server in the 'example.com' client, it communicates with the AAA server in the 'example.com'
domain to determine if the DOTS client is authorized to request DDOS domain to determine if the DOTS client is authorized to request DDoS
mitigation. If the DOTS client is not authorized, a 4.01 mitigation. If the DOTS client is not authorized, a 4.01
(Unauthorized) is returned in the response to the DOTS client. In (Unauthorized) is returned in the response to the DOTS client. In
this example, the DOTS gateway only allows the application server and this example, the DOTS gateway only allows the application server and
DDOS detector to request DDOS mitigation, but does not permit the DDoS attack detector to request DDOS mitigation, but does not permit
user of type 'guest' to request DDOS mitigation. the user of type 'guest' to request DDoS mitigation.
Also, DOTS gateway and DOTS server located in different domains MUST Also, DOTS gateways and servers located in different domains MUST
perform mutual authentication (e.g., using certificates). A DOTS perform mutual authentication (e.g., using certificates). A DOTS
server will only allow a DOTS gateway with a certificate for a server will only allow a DOTS gateway with a certificate for a
particular domain to request mitigation for that domain. In particular domain to request mitigation for that domain. In
reference to Figure 24, the DOTS server only allows the DOTS gateway reference to Figure 24, the DOTS server only allows the DOTS gateway
to request mitigation for 'example.com' domain and not for other to request mitigation for 'example.com' domain and not for other
domains. domains.
9. IANA Considerations 9. IANA Considerations
This specification registers a service port (Section 9.1), an URI This specification registers a service port (Section 9.1), an URI
skipping to change at page 59, line 28 skipping to change at page 61, line 28
registry for mappings to CBOR (Section 9.4). registry for mappings to CBOR (Section 9.4).
9.1. DOTS Signal Channel UDP and TCP Port Number 9.1. DOTS Signal Channel UDP and TCP Port Number
IANA is requested to assign the port number TBD to the DOTS signal IANA is requested to assign the port number TBD to the DOTS signal
channel protocol for both UDP and TCP from the "Service Name and channel protocol for both UDP and TCP from the "Service Name and
Transport Protocol Port Number Registry" available at Transport Protocol Port Number Registry" available at
https://www.iana.org/assignments/service-names-port-numbers/service- https://www.iana.org/assignments/service-names-port-numbers/service-
names-port-numbers.xhtml. names-port-numbers.xhtml.
It is strongly suggested that the port number 4646 is to be assigned. The assignment of port number 4646 is strongly suggested, as 4646 is
4646 is the ASCII decimal value for ".." (DOTS). the ASCII decimal value for ".." (DOTS).
9.2. Well-Known 'dots' URI 9.2. Well-Known 'dots' URI
This document requests IANA to register the 'dots' well-known URI in This document requests IANA to register the 'dots' well-known URI in
the Well-Known URIs registry (https://www.iana.org/assignments/well- the Well-Known URIs registry (https://www.iana.org/assignments/well-
known-uris/well-known-uris.xhtml) as defined by [RFC5785]. known-uris/well-known-uris.xhtml) as defined by [RFC5785].
URI suffix: dots URI suffix: dots
Change controller: IETF Change controller: IETF
skipping to change at page 60, line 31 skipping to change at page 62, line 31
Values from that registry MUST be assigned via Expert Review Values from that registry MUST be assigned via Expert Review
[RFC8126]. [RFC8126].
9.4.1. Registration Template 9.4.1. Registration Template
Parameter name: Parameter name:
Parameter name as used in the DOTS signal channel. Parameter name as used in the DOTS signal channel.
CBOR Key Value: CBOR Key Value:
Key value for the parameter. The key value MUST be an integer in Key value for the parameter. The key value MUST be an integer in
the range of 1 to 65536. The key values in the range of 32768 to the 1-65536 range. The key values in the 32758-65536 range are
65536 are assigned for Vendor-Specific parameters. assigned to Vendor-Specific parameters.
CBOR Major Type: CBOR Major Type:
CBOR Major type and optional tag for the claim. CBOR Major type and optional tag for the claim.
Change Controller: Change Controller:
For Standards Track RFCs, list the "IESG". For others, give the For Standards Track RFCs, list the "IESG". For others, give the
name of the responsible party. Other details (e.g., postal name of the responsible party. Other details (e.g., postal
address, email address, home page URI) may also be included. address, email address, home page URI) may also be included.
Specification Document(s): Specification Document(s):
skipping to change at page 61, line 19 skipping to change at page 63, line 19
o CBOR Major Type: 5 o CBOR Major Type: 5
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
o Parameter Name: mitigation-id o Parameter Name: mitigation-id
o CBOR Key Value: 3 o CBOR Key Value: 3
o CBOR Major Type: 0 o CBOR Major Type: 0
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
o Parameter Name: target-ip o Parameter Name: acl-type
o CBOR Key Value: 4 o CBOR Key Value: 4
o CBOR Major Type: 4 o CBOR Major Type: 4
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
o Parameter Name: target-port-range o Parameter Name: target-port-range
o CBOR Key Value: 5 o CBOR Key Value: 5
o CBOR Major Type: 4 o CBOR Major Type: 4
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
skipping to change at page 66, line 7 skipping to change at page 68, line 7
o CBOR Major Type: 0 o CBOR Major Type: 0
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
o Parameter Name: conflict-scope o Parameter Name: conflict-scope
o CBOR Key Value: 41 o CBOR Key Value: 41
o CBOR Major Type: 5 o CBOR Major Type: 5
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
o Parameter Name: acl-name
o CBOR Key Value: 42
o CBOR Major Type: 2
o Change Controller: IESG
o Specification Document(s): this document
o Parameter Name: acl-type
o CBOR Key Value: 43
o CBOR Major Type: 3
o Change Controller: IESG
o Specification Document(s): this document
o Parameter Name: config-interval
o CBOR Key Value: 44
o CBOR Major Type: 0
o Change Controller: IESG
o Specification Document(s): this document
9.5. DOTS Signal Channel YANG Module 9.5. DOTS Signal Channel YANG Module
This document requests IANA to register the following URI in the This document requests IANA to register the following URI in the
"IETF XML Registry" [RFC3688]: "IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-dots-signal URI: urn:ietf:params:xml:ns:yang:ietf-dots-signal
Registrant Contact: The IESG. Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace. XML: N/A; the requested URI is an XML namespace.
This document requests IANA to register the following YANG module in This document requests IANA to register the following YANG module in
skipping to change at page 66, line 30 skipping to change at page 68, line 48
namespace: urn:ietf:params:xml:ns:yang:ietf-dots-signal namespace: urn:ietf:params:xml:ns:yang:ietf-dots-signal
prefix: signal prefix: signal
reference: RFC XXXX reference: RFC XXXX
10. Implementation Status 10. Implementation Status
[Note to RFC Editor: Please remove this section and reference to [Note to RFC Editor: Please remove this section and reference to
[RFC7942] prior to publication.] [RFC7942] prior to publication.]
This section records the status of known implementations of the This section records the status of known implementations of the
protocol defined by this specification at the time of posting of this protocol defined by this specification at the time of posting this
Internet-Draft, and is based on a proposal described in [RFC7942]. Internet-Draft, and is based upon a proposal described in [RFC7942].
The description of implementations in this section is intended to The description of implementations in this section is intended to
assist the IETF in its decision processes in progressing drafts to assist the IETF in its decision-making process when progressing
RFCs. Please note that the listing of any individual implementation drafts to RFCs. Please note that the listing of any individual
here does not imply endorsement by the IETF. Furthermore, no effort implementation here does not imply endorsement by the IETF.
has been spent to verify the information presented here that was Furthermore, no effort has been spent to verify the information
supplied by IETF contributors. This is not intended as, and must not presented here, and which was provided by individuals. This is not
be construed to be, a catalog of available implementations or their intended as, and must not be construed to be, a catalog of available
features. Readers are advised to note that other implementations may implementations or features. Readers are advised to note that other
exist. implementations may exist.
According to [RFC7942], "this will allow reviewers and working groups According to [RFC7942], "this will allow reviewers and working groups
to assign due consideration to documents that have the benefit of to assign due consideration to documents that have the benefit of
running code, which may serve as evidence of valuable experimentation running code, which may serve as evidence of valuable experimentation
and feedback that have made the implemented protocols more mature. and feedback that have made the implemented protocols more mature.
It is up to the individual working groups to use this information as It is up to the individual working groups to use this information as
they see fit". they see fit".
10.1. nttdots 10.1. nttdots
Organization: NTT Communication is developing a DOTS client and Organization: NTT Communication is developing a DOTS client and
DOTS server software based on DOTS signal channel specified in DOTS server software based on DOTS signal channel specified in
this draft. It will be open-sourced. this draft. It will be open-sourced.
Description: Early implementation of DOTS protocol. It is aimed to Description: Early implementation of DOTS protocol. It is aimed to
implement a full DOTS protocol spec in accordance with maturing of implement a full DOTS protocol specification in accordance with
DOTS protocol itself. the nurturing DOTS protocol.
Implementation: https://github.com/nttdots/go-dots Implementation: https://github.com/nttdots/go-dots
Level of maturity: It is a early implementation of DOTS protocol. Level of maturity: It is an early implementation of the DOTS
Messaging between DOTS clients and DOTS servers has been tested. protocol. Messaging between DOTS clients and DOTS servers has
Level of maturity will increase in accordance with maturing of been tested. Level of maturity will increase in accordance with
DOTS protocol itself. the nurturing DOTS protocol.
Coverage: Capability of DOTS client: sending DOTS messages to the Coverage: Capability of DOTS client: sending DOTS messages to the
DOTS server in CoAP over DTLS as dots-signal. Capability of DOTS DOTS server in CoAP over DTLS as dots-signal. Capability of DOTS
server: receiving dots-signal, validating received dots-signal, server: receiving dots-signal, validating received dots-signal,
starting mitigation by handing over the dots-signal to DDOS starting mitigation by handing over the dots-signal to DDOS
mitigator. mitigator.
Licensing: It will be open-sourced with BSD 3-clause license. Licensing: It will be open-sourced with BSD 3-clause license.
Implementation experience: It is implemented in Go-lang. Core Implementation experience: It is implemented in Go-lang. Core
specification of signaling is mature to be implemented, however, specification of signaling is mature to be implemented, however,
finding good libraries(like DTLS, CoAP) is rather difficult. finding good libraries(like DTLS, CoAP) is rather difficult.
Contact: Kaname Nishizuka <kaname@nttv6.jp> Contact: Kaname Nishizuka <kaname@nttv6.jp>
11. Security Considerations 11. Security Considerations
Authenticated encryption MUST be used for data confidentiality and Authenticated encryption MUST be used for data confidentiality and
message integrity. The interaction between the DOTS agents requires message integrity. The interaction between the DOTS agents requires
Datagram Transport Layer Security (DTLS) and Transport Layer Security Datagram Transport Layer Security (DTLS) and Transport Layer Security
(TLS) with a cipher suite offering confidentiality protection and the (TLS) with a cipher suite offering confidentiality protection and the
guidance given in [RFC7525] MUST be followed to avoid attacks on guidance given in [RFC7525] MUST be followed to avoid attacks on
(D)TLS. (D)TLS. The (D)TLS protocol profile for DOTS signal channel is
specified in Section 7.
A single DOTS signal channel between DOTS agents can be used to A single DOTS signal channel between DOTS agents can be used to
exchange multiple DOTS signal messages. To reduce DOTS client and exchange multiple DOTS signal messages. To reduce DOTS client and
DOTS server workload, DOTS client SHOULD re-use the (D)TLS session. DOTS server workload, DOTS clients SHOULD re-use the (D)TLS session.
If TCP is used between DOTS agents, an attacker may be able to inject If TCP is used between DOTS agents, an attacker may be able to inject
RST packets, bogus application segments, etc., regardless of whether RST packets, bogus application segments, etc., regardless of whether
TLS authentication is used. Because the application data is TLS TLS authentication is used. Because the application data is TLS
protected, this will not result in the application receiving bogus protected, this will not result in the application receiving bogus
data, but it will constitute a DoS on the connection. This attack data, but it will constitute a DoS on the connection. This attack
can be countered by using TCP-AO [RFC5925]. If TCP-AO is used, then can be countered by using TCP-AO [RFC5925]. If TCP-AO is used, then
any bogus packets injected by an attacker will be rejected by the any bogus packets injected by an attacker will be rejected by the
TCP-AO integrity check and therefore will never reach the TLS layer. TCP-AO integrity check and therefore will never reach the TLS layer.
In order to prevent leaking internal information outside a client- In order to prevent leaking internal information outside a client-
domain, DOTS gateways located in the client-domain SHOULD NOT reveal domain, DOTS gateways located in the client-domain SHOULD NOT reveal
the identity of internal DOTS clients (client-identifier) unless the identification information that pertains to internal DOTS clients
explicitly configured to do so. (client-identifier) unless explicitly configured to do so.
Special care should be taken in order to ensure that the activation Special care should be taken in order to ensure that the activation
of the proposed mechanism won't have an impact on the stability of of the proposed mechanism will not impact the stability of the
the network (including connectivity and services delivered over that network (including connectivity and services delivered over that
network). network).
Involved functional elements in the cooperation system must establish Involved functional elements involved in the DDoS cooperation system
exchange instructions and notification over a secure and must exchange instructions and notification over a secure and
authenticated channel. Adequate filters can be enforced to avoid authenticated channel. Adequate filters can apply to avoid that
that nodes outside a trusted domain can inject request such as nodes outside a trusted domain can inject illegitimate requests.
deleting filtering rules. Nevertheless, attacks can be initiated Attacks can be initiated from within the trusted domain if an entity
from within the trusted domain if an entity has been corrupted. has been corrupted. Adequate means to monitor trusted nodes should
Adequate means to monitor trusted nodes should also be enabled. also be enabled.
12. Contributors 12. Contributors
The following individuals have contributed to this document: The following individuals have contributed to this document:
Mike Geller Cisco Systems, Inc. 3250 Florida 33309 USA Email: Mike Geller Cisco Systems, Inc. 3250 Florida 33309 USA Email:
mgeller@cisco.com mgeller@cisco.com
Robert Moskowitz HTT Consulting Oak Park, MI 42837 United States Robert Moskowitz HTT Consulting Oak Park, MI 42837 United States
Email: rgm@htt-consult.com Email: rgm@htt-consult.com
skipping to change at page 70, line 49 skipping to change at page 73, line 19
[RFC8132] van der Stok, P., Bormann, C., and A. Sehgal, "PATCH and [RFC8132] van der Stok, P., Bormann, C., and A. Sehgal, "PATCH and
FETCH Methods for the Constrained Application Protocol FETCH Methods for the Constrained Application Protocol
(CoAP)", RFC 8132, DOI 10.17487/RFC8132, April 2017, (CoAP)", RFC 8132, DOI 10.17487/RFC8132, April 2017,
<https://www.rfc-editor.org/info/rfc8132>. <https://www.rfc-editor.org/info/rfc8132>.
14.2. Informative References 14.2. Informative References
[I-D.ietf-core-comi] [I-D.ietf-core-comi]
Veillette, M., Stok, P., Pelov, A., and A. Bierman, "CoAP Veillette, M., Stok, P., Pelov, A., and A. Bierman, "CoAP
Management Interface", draft-ietf-core-comi-01 (work in Management Interface", draft-ietf-core-comi-02 (work in
progress), July 2017. progress), December 2017.
[I-D.ietf-core-yang-cbor] [I-D.ietf-core-yang-cbor]
Veillette, M., Pelov, A., Somaraju, A., Turner, R., and A. Veillette, M., Pelov, A., Somaraju, A., Turner, R., and A.
Minaburo, "CBOR Encoding of Data Modeled with YANG", Minaburo, "CBOR Encoding of Data Modeled with YANG",
draft-ietf-core-yang-cbor-05 (work in progress), August draft-ietf-core-yang-cbor-05 (work in progress), August
2017. 2017.
[I-D.ietf-dots-architecture] [I-D.ietf-dots-architecture]
Mortensen, A., Andreasen, F., Reddy, T., Mortensen, A., Andreasen, F., Reddy, T.,
christopher_gray3@cable.comcast.com, c., Compton, R., and christopher_gray3@cable.comcast.com, c., Compton, R., and
N. Teague, "Distributed-Denial-of-Service Open Threat N. Teague, "Distributed-Denial-of-Service Open Threat
Signaling (DOTS) Architecture", draft-ietf-dots- Signaling (DOTS) Architecture", draft-ietf-dots-
architecture-05 (work in progress), October 2017. architecture-05 (work in progress), October 2017.
[I-D.ietf-dots-data-channel] [I-D.ietf-dots-data-channel]
Reddy, T., Boucadair, M., Nishizuka, K., Xia, L., Patil, Reddy, T., Boucadair, M., Nishizuka, K., Xia, L., Patil,
P., Mortensen, A., and N. Teague, "Distributed Denial-of- P., Mortensen, A., and N. Teague, "Distributed Denial-of-
Service Open Threat Signaling (DOTS) Data Channel", draft- Service Open Threat Signaling (DOTS) Data Channel", draft-
ietf-dots-data-channel-08 (work in progress), November ietf-dots-data-channel-10 (work in progress), December
2017. 2017.
[I-D.ietf-dots-requirements] [I-D.ietf-dots-requirements]
Mortensen, A., Moskowitz, R., and T. Reddy, "Distributed Mortensen, A., Moskowitz, R., and T. Reddy, "Distributed
Denial of Service (DDoS) Open Threat Signaling Denial of Service (DDoS) Open Threat Signaling
Requirements", draft-ietf-dots-requirements-07 (work in Requirements", draft-ietf-dots-requirements-08 (work in
progress), October 2017. progress), December 2017.
[I-D.ietf-dots-use-cases] [I-D.ietf-dots-use-cases]
Dobbins, R., Migault, D., Fouant, S., Moskowitz, R., Dobbins, R., Migault, D., Fouant, S., Moskowitz, R.,
Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS
Open Threat Signaling", draft-ietf-dots-use-cases-09 (work Open Threat Signaling", draft-ietf-dots-use-cases-09 (work
in progress), November 2017. in progress), November 2017.
[I-D.ietf-netmod-yang-tree-diagrams] [I-D.ietf-netmod-yang-tree-diagrams]
Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft- Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
ietf-netmod-yang-tree-diagrams-02 (work in progress), ietf-netmod-yang-tree-diagrams-02 (work in progress),
October 2017. October 2017.
[I-D.ietf-tls-dtls13] [I-D.ietf-tls-dtls13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version Datagram Transport Layer Security (DTLS) Protocol Version
1.3", draft-ietf-tls-dtls13-22 (work in progress), 1.3", draft-ietf-tls-dtls13-22 (work in progress),
November 2017. November 2017.
[I-D.ietf-tls-tls13] [I-D.ietf-tls-tls13]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", draft-ietf-tls-tls13-21 (work in progress), Version 1.3", draft-ietf-tls-tls13-22 (work in progress),
July 2017. November 2017.
[proto_numbers] [proto_numbers]
"IANA, "Protocol Numbers"", 2011, "IANA, "Protocol Numbers"", 2011,
<http://www.iana.org/assignments/protocol-numbers>. <http://www.iana.org/assignments/protocol-numbers>.
[RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791, [RFC0791] Postel, J., "Internet Protocol", STD 5, RFC 791,
DOI 10.17487/RFC0791, September 1981, DOI 10.17487/RFC0791, September 1981,
<https://www.rfc-editor.org/info/rfc791>. <https://www.rfc-editor.org/info/rfc791>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
skipping to change at page 73, line 5 skipping to change at page 75, line 18
[RFC4987] Eddy, W., "TCP SYN Flooding Attacks and Common [RFC4987] Eddy, W., "TCP SYN Flooding Attacks and Common
Mitigations", RFC 4987, DOI 10.17487/RFC4987, August 2007, Mitigations", RFC 4987, DOI 10.17487/RFC4987, August 2007,
<https://www.rfc-editor.org/info/rfc4987>. <https://www.rfc-editor.org/info/rfc4987>.
[RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig, [RFC5077] Salowey, J., Zhou, H., Eronen, P., and H. Tschofenig,
"Transport Layer Security (TLS) Session Resumption without "Transport Layer Security (TLS) Session Resumption without
Server-Side State", RFC 5077, DOI 10.17487/RFC5077, Server-Side State", RFC 5077, DOI 10.17487/RFC5077,
January 2008, <https://www.rfc-editor.org/info/rfc5077>. January 2008, <https://www.rfc-editor.org/info/rfc5077>.
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389,
DOI 10.17487/RFC5389, October 2008,
<https://www.rfc-editor.org/info/rfc5389>.
[RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with [RFC6555] Wing, D. and A. Yourtchenko, "Happy Eyeballs: Success with
Dual-Stack Hosts", RFC 6555, DOI 10.17487/RFC6555, April Dual-Stack Hosts", RFC 6555, DOI 10.17487/RFC6555, April
2012, <https://www.rfc-editor.org/info/rfc6555>. 2012, <https://www.rfc-editor.org/info/rfc6555>.
[RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown, [RFC6724] Thaler, D., Ed., Draves, R., Matsumoto, A., and T. Chown,
"Default Address Selection for Internet Protocol Version 6 "Default Address Selection for Internet Protocol Version 6
(IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012, (IPv6)", RFC 6724, DOI 10.17487/RFC6724, September 2012,
<https://www.rfc-editor.org/info/rfc6724>. <https://www.rfc-editor.org/info/rfc6724>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013,
<https://www.rfc-editor.org/info/rfc6887>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030, "Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013, DOI 10.17487/RFC7030, October 2013,
<https://www.rfc-editor.org/info/rfc7030>. <https://www.rfc-editor.org/info/rfc7030>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>. October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP [RFC7413] Cheng, Y., Chu, J., Radhakrishnan, S., and A. Jain, "TCP
skipping to change at page 74, line 5 skipping to change at page 76, line 31
[RFC7924] Santesson, S. and H. Tschofenig, "Transport Layer Security [RFC7924] Santesson, S. and H. Tschofenig, "Transport Layer Security
(TLS) Cached Information Extension", RFC 7924, (TLS) Cached Information Extension", RFC 7924,
DOI 10.17487/RFC7924, July 2016, DOI 10.17487/RFC7924, July 2016,
<https://www.rfc-editor.org/info/rfc7924>. <https://www.rfc-editor.org/info/rfc7924>.
[RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running [RFC7942] Sheffer, Y. and A. Farrel, "Improving Awareness of Running
Code: The Implementation Status Section", BCP 205, Code: The Implementation Status Section", BCP 205,
RFC 7942, DOI 10.17487/RFC7942, July 2016, RFC 7942, DOI 10.17487/RFC7942, July 2016,
<https://www.rfc-editor.org/info/rfc7942>. <https://www.rfc-editor.org/info/rfc7942>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/info/rfc7951>.
[RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage [RFC8085] Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085, Guidelines", BCP 145, RFC 8085, DOI 10.17487/RFC8085,
March 2017, <https://www.rfc-editor.org/info/rfc8085>. March 2017, <https://www.rfc-editor.org/info/rfc8085>.
Authors' Addresses Authors' Addresses
Tirumaleswar Reddy Tirumaleswar Reddy
McAfee, Inc. McAfee, Inc.
Embassy Golf Link Business Park Embassy Golf Link Business Park
Bangalore, Karnataka 560071 Bangalore, Karnataka 560071
 End of changes. 247 change blocks. 
906 lines changed or deleted 1078 lines changed or added

This html diff was produced by rfcdiff 1.48. The latest version is available from http://tools.ietf.org/tools/rfcdiff/