< draft-ietf-dots-signal-channel-08.txt   draft-ietf-dots-signal-channel-09.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: May 27, 2018 Orange Expires: May 31, 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.
November 23, 2017 November 27, 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-08 draft-ietf-dots-signal-channel-09
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. A companion traffic mitigation on behalf of the requesting client.
document defines the DOTS data channel, a separate reliable
communication layer for DOTS management and configuration. A companion document defines the DOTS data channel, a separate
reliable communication layer for DOTS management and configuration.
Editorial Note (To be removed by RFC Editor)
Please update these statements with the RFC number to be assigned to
this document:
o "This version of this YANG module is part of RFC XXXX;"
o "RFC XXXX: Distributed Denial-of-Service Open Threat Signaling
(DOTS) Signal Channel";
o "| 3.00 | Alternate server | [RFCXXXX] |"
o reference: RFC XXXX
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on May 27, 2018. This Internet-Draft will expire on May 31, 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.
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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 . . . . . . . . . . . 3 2. Notational Conventions and Terminology . . . . . . . . . . . 5
3. Solution Overview . . . . . . . . . . . . . . . . . . . . . . 4 3. Design Overview . . . . . . . . . . . . . . . . . . . . . . . 5
4. Happy Eyeballs for DOTS Signal Channel . . . . . . . . . . . 5 4. DOTS Signal Channel: Messages & Behaviors . . . . . . . . . . 7
5. DOTS Signal Channel . . . . . . . . . . . . . . . . . . . . . 6 4.1. DOTS Server(s) Discovery . . . . . . . . . . . . . . . . 7
5.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. CoAP URIs . . . . . . . . . . . . . . . . . . . . . . . . 7
5.2. DOTS Signal YANG Module . . . . . . . . . . . . . . . . . 8 4.3. Happy Eyeballs for DOTS Signal Channel . . . . . . . . . 8
5.2.1. Mitigation Request YANG Module Tree Structure . . . . 8 4.4. DOTS Mitigation Methods . . . . . . . . . . . . . . . . . 9
5.2.2. Mitigation Request YANG Module . . . . . . . . . . . 9 4.4.1. Request Mitigation . . . . . . . . . . . . . . . . . 10
5.2.3. Session Configuration YANG Module Tree Structure . . 11 4.4.2. Withdraw a Mitigation . . . . . . . . . . . . . . . . 18
5.2.4. Session Configuration YANG Module . . . . . . . . . . 12 4.4.3. Retrieve Information Related to a Mitigation . . . . 19
5.3. CoAP URIs . . . . . . . . . . . . . . . . . . . . . . . . 14 4.4.4. Efficacy Update from DOTS Clients . . . . . . . . . . 25
5.4. Mitigation Request . . . . . . . . . . . . . . . . . . . 15 4.5. DOTS Signal Channel Session Configuration . . . . . . . . 27
5.4.1. Requesting mitigation . . . . . . . . . . . . . . . . 15 4.5.1. Discover Configuration Parameters . . . . . . . . . . 28
5.4.2. Withdraw a DOTS Signal . . . . . . . . . . . . . . . 24 4.5.2. Convey DOTS Signal Channel Session Configuration . . 30
5.4.3. Retrieving a DOTS Signal . . . . . . . . . . . . . . 25 4.5.3. Delete DOTS Signal Channel Session Configuration . . 34
5.4.4. Efficacy Update from DOTS Client . . . . . . . . . . 30 4.6. Redirected Signaling . . . . . . . . . . . . . . . . . . 35
5.5. DOTS Signal Channel Session Configuration . . . . . . . . 32 4.7. Heartbeat Mechanism . . . . . . . . . . . . . . . . . . . 36
5.5.1. Discover Configuration Parameters . . . . . . . . . . 33 5. DOTS Signal Channel YANG Modules . . . . . . . . . . . . . . 37
5.5.2. Convey DOTS Signal Channel Session Configuration . . 35 5.1. Mitigation Request YANG Module Tree Structure . . . . . . 37
5.5.3. Delete DOTS Signal Channel Session Configuration . . 39 5.2. Mitigation Request YANG Module . . . . . . . . . . . . . 38
5.6. Redirected Signaling . . . . . . . . . . . . . . . . . . 40 5.3. Session Configuration YANG Module Tree Structure . . . . 41
5.7. Heartbeat Mechanism . . . . . . . . . . . . . . . . . . . 41 5.4. Session Configuration YANG Module . . . . . . . . . . . . 41
6. Mapping parameters to CBOR . . . . . . . . . . . . . . . . . 42 6. Mapping Parameters to CBOR . . . . . . . . . . . . . . . . . 44
7. (D)TLS Protocol Profile and Performance considerations . . . 43 7. (D)TLS Protocol Profile and Performance Considerations . . . 45
7.1. MTU and Fragmentation Issues . . . . . . . . . . . . . . 45 7.1. (D)TLS Protocol Profile . . . . . . . . . . . . . . . . . 46
8. (D)TLS 1.3 considerations . . . . . . . . . . . . . . . . . . 45 7.2. MTU and Fragmentation . . . . . . . . . . . . . . . . . . 47
8. (D)TLS 1.3 Considerations . . . . . . . . . . . . . . . . . . 48
9. Mutual Authentication of DOTS Agents & Authorization of DOTS 9. Mutual Authentication of DOTS Agents & Authorization of DOTS
Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Clients . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 48 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 50
10.1. DOTS Signal Channel UDP and TCP Port Number . . . . . . 48 10.1. DOTS Signal Channel UDP and TCP Port Number . . . . . . 50
10.2. Well-Known 'dots' URI . . . . . . . . . . . . . . . . . 48 10.2. Well-Known 'dots' URI . . . . . . . . . . . . . . . . . 50
10.3. CoAP Response Code . . . . . . . . . . . . . . . . . . . 48 10.3. CoAP Response Code . . . . . . . . . . . . . . . . . . . 50
10.4. DOTS signal channel CBOR Mappings Registry . . . . . . . 48 10.4. DOTS Signal Channel CBOR Mappings Registry . . . . . . . 51
10.4.1. Registration Template . . . . . . . . . . . . . . . 49 10.4.1. Registration Template . . . . . . . . . . . . . . . 51
10.4.2. Initial Registry Contents . . . . . . . . . . . . . 49 10.4.2. Initial Registry Contents . . . . . . . . . . . . . 51
10.5. YANG Modules . . . . . . . . . . . . . . . . . . . . . . 56
11. Implementation Status . . . . . . . . . . . . . . . . . . . . 54 11. Implementation Status . . . . . . . . . . . . . . . . . . . . 56
11.1. nttdots . . . . . . . . . . . . . . . . . . . . . . . . 54 11.1. nttdots . . . . . . . . . . . . . . . . . . . . . . . . 57
12. Security Considerations . . . . . . . . . . . . . . . . . . . 55 12. Security Considerations . . . . . . . . . . . . . . . . . . . 57
13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 56 13. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 58
14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 56 14. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 58
15. References . . . . . . . . . . . . . . . . . . . . . . . . . 56 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 59
15.1. Normative References . . . . . . . . . . . . . . . . . . 56 15.1. Normative References . . . . . . . . . . . . . . . . . . 59
15.2. Informative References . . . . . . . . . . . . . . . . . 58 15.2. Informative References . . . . . . . . . . . . . . . . . 60
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 61 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 63
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.
In many cases, it may not be possible for network administrators to
determine the causes of an attack, but instead just realize that
certain resources seem to be under attack. This document defines a
lightweight protocol permitting a DOTS client to request mitigation
from one or more DOTS servers for protection against detected,
suspected, or anticipated attacks . This protocol enables cooperation
between DOTS agents to permit a highly-automated network defense that
is robust, reliable and secure.
The document adheres to the DOTS architecture
[I-D.ietf-dots-architecture]. The requirements for DOTS signal
channel protocol are obtained from [I-D.ietf-dots-requirements].
This document satisfies all the use cases discussed in
[I-D.ietf-dots-use-cases].
This is a companion document to the DOTS data channel specification
[I-D.ietf-dots-data-channel] that defines a configuration and bulk
data exchange mechanism supporting the DOTS signal channel.
2. Notational Conventions and Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119].
(D)TLS: For brevity this term is used for statements that apply to
both Transport Layer Security [RFC5246] and Datagram Transport Layer
Security [RFC6347]. Specific terms will be used for any statement
that applies to either protocol alone.
The reader should be familiar with the terms defined in
[I-D.ietf-dots-architecture].
3. Solution Overview
Network applications have finite resources like CPU cycles, number of Network applications have finite resources like CPU cycles, number of
processes or threads they can create and use, maximum number of processes or threads they can create and use, maximum number of
simultaneous connections it can handle, limited resources of the simultaneous connections it can handle, limited resources of the
control plane, etc. When processing network traffic, such control plane, etc. When processing network traffic, such
applications are supposed to use these resources to offer the applications are supposed to use these resources to offer the
intended task in the most efficient fashion. However, an attacker intended task in the most efficient fashion. However, a DDoS
may be able to prevent an application from performing its intended attacker may be able to prevent an application from performing its
task by causing the application to exhaust the finite supply of a intended task by causing the application to exhaust the finite supply
specific resource. of a specific resource.
TCP DDoS SYN-flood, for example, is a memory-exhaustion attack on the TCP DDoS SYN-flood, for example, is a memory-exhaustion attack on the
victim and ACK-flood is a CPU exhaustion attack on the victim victim and ACK-flood is a CPU exhaustion attack on the victim
([RFC4987]). Attacks on the link are carried out by sending enough
[RFC4987]. Attacks on the link are carried out by sending enough
traffic such that the link becomes excessively congested, and traffic such that the link becomes excessively congested, and
legitimate traffic suffers high packet loss. Stateful firewalls can legitimate traffic suffers high packet loss. Stateful firewalls can
also be attacked by sending traffic that causes the firewall to hold also be attacked by sending traffic that causes the firewall to hold
excessive state. The firewall then runs out of memory, and can no excessive state. The firewall then runs out of memory, and can no
longer instantiate the state required to pass legitimate flows. longer instantiate the state required to pass legitimate flows.
Other possible DDoS attacks are discussed in [RFC4732]. Other possible DDoS attacks are discussed in [RFC4732].
In each of the cases described above, the possible arrangements In many cases, it may not be possible for network administrators to
between the DOTS client and DOTS server to mitigate the attack are determine the causes of an attack, but instead just realize that
discussed in [I-D.ietf-dots-use-cases]. An example of network certain resources seem to be under attack. This document defines a
diagram showing a deployment of these elements is shown in Figure 1. lightweight protocol permitting a DOTS client to request mitigation
Architectural relationships between involved DOTS agents is explained from one or more DOTS servers for protection against detected,
in [I-D.ietf-dots-architecture]. In this example, the DOTS server is suspected, or anticipated attacks. This protocol enables cooperation
operating on the access network. between DOTS agents to permit a highly-automated network defense that
is robust, reliable and secure.
An example of network diagram showing a deployment of DOTS agents is
shown in Figure 1. In this example, the DOTS server is operating on
the access network.
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)
skipping to change at page 5, line 25 skipping to change at page 5, line 10
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 a firewall protecting services owned and operated by an client is a firewall protecting services owned and operated by an
domain, while the DOTS server is owned and operated by a different domain, while the DOTS server is owned and operated by a different
domain providing DDoS mitigation services. That domain providing domain providing DDoS mitigation services. That domain providing
DDoS mitigation service might, or might not, also provide Internet DDoS mitigation service might, or might not, also provide Internet
access service to the website operator. access service to the website operator.
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. administrative domain as the mitigator. The DOTS client can
communicate directly with the DOTS server or indirectly via a DOTS
The DOTS client can communicate directly with the DOTS server or gateway.
indirectly via a DOTS gateway.
This document focuses on the DOTS signal channel.
4. Happy Eyeballs for DOTS Signal Channel The document adheres to the DOTS architecture
[I-D.ietf-dots-architecture]. The requirements for DOTS signal
channel protocol are obtained from [I-D.ietf-dots-requirements].
This document satisfies all the use cases discussed in
[I-D.ietf-dots-use-cases].
DOTS signaling can happen with DTLS [RFC6347] over UDP and TLS This document focuses on the DOTS signal channel. This is a
[RFC5246] over TCP. A DOTS client can use DNS to determine the IP companion document to the DOTS data channel specification
address(es) of a DOTS server or a DOTS client may be provided with [I-D.ietf-dots-data-channel] that defines a configuration and bulk
the list of DOTS server IP addresses. The DOTS client MUST know a data exchange mechanism supporting the DOTS signal channel.
DOTS server's domain name; hard-coding the domain name of the DOTS
server into software is NOT RECOMMENDED in case the domain name is
not valid or needs to change for legal or other reasons. The DOTS
client performs A and/or AAAA record lookup of the domain name and
the result will be a list of IP addresses, each of which can be used
to contact the DOTS server using UDP and TCP.
If an IPv4 path to reach a DOTS server is found, but the DOTS 2. Notational Conventions and Terminology
server's IPv6 path is not working, a dual-stack DOTS client can
experience a significant connection delay compared to an IPv4-only
DOTS client. The other problem is that if a middlebox between the
DOTS client and DOTS server is configured to block UDP, the DOTS
client will fail to establish a DTLS session with the DOTS server and
will, then, have to fall back to TLS over TCP incurring significant
connection delays. [I-D.ietf-dots-requirements] discusses that DOTS
client and server will have to support both connectionless and
connection-oriented protocols.
To overcome these connection setup problems, the DOTS client can try The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
connecting to the DOTS server using both IPv6 and IPv4, and try both "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
DTLS over UDP and TLS over TCP in a fashion similar to the Happy "OPTIONAL" in this document are to be interpreted as described in
Eyeballs mechanism [RFC6555]. These connection attempts are [RFC2119].
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,
UDP over IPv4, TCP over IPv6, and finally TCP over IPv4, which
adheres to address preference order [RFC6724] and the DOTS preference
that UDP be used over TCP (to avoid TCP's head of line blocking).
DOTS client DOTS server (D)TLS: For brevity this term is used for statements that apply to
| | both Transport Layer Security [RFC5246] and Datagram Transport Layer
|--DTLS ClientHello, IPv6 ---->X | Security [RFC6347]. Specific terms will be used for any statement
|--TCP SYN, IPv6-------------->X | that applies to either protocol alone.
|--DTLS ClientHello, IPv4 ---->X |
|--TCP SYN, IPv4----------------------------------------->|
|--DTLS ClientHello, IPv6 ---->X |
|--TCP SYN, IPv6-------------->X |
|<-TCP SYNACK---------------------------------------------|
|--DTLS ClientHello, IPv4 ---->X |
|--TCP ACK----------------------------------------------->|
|<------------Establish TLS Session---------------------->|
|----------------DOTS signal----------------------------->|
| |
Figure 3: Happy Eyeballs The reader should be familiar with the terms defined in
[I-D.ietf-dots-architecture].
In reference to Figure 3, the DOTS client sends two TCP SYNs and two The meaning of the symbols in YANG tree diagrams is defined in
DTLS ClientHello messages at the same time over IPv6 and IPv4. In [I-D.ietf-netmod-yang-tree-diagrams].
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
because there is no long delay before using IPv4 and TCP. The DOTS
client repeats the mechanism to discover if DOTS signaling with DTLS
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
SHOULD NOT be done more frequently than every 24 hours and MUST NOT
be done more frequently than every 5 minutes.
5. DOTS Signal Channel 3. Design Overview
5.1. 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. CoAP's
expectation of packet loss, support for asynchronous non-confirmable expectation of packet loss, support for asynchronous non-confirmable
messaging, congestion control, small message overhead limiting the messaging, congestion control, small message overhead limiting the
need for fragmentation, use of minimal resources, and support for need for fragmentation, use of minimal resources, and support for
(D)TLS make it a good foundation on which to build the DOTS signaling (D)TLS make it a good foundation on which to build the DOTS signaling
mechanism. mechanism.
The DOTS signal channel is layered on existing standards (Figure 4). The DOTS signal channel is layered on existing standards (Figure 3).
By default, DOTS signal channel MUST run over port number TBD as
defined in Section 10.1, for both UDP and TCP, unless the DOTS server
has mutual agreement with its DOTS clients to use a port other than
TBD for DOTS signal channel, or DOTS clients supports means to
dynamically discover the ports used by their DOTS servers. In order
to use a distinct port number (vs. TBD), DOTS clients and servers
should support a configurable parameter to supply the port number to
use.
+--------------+ +--------------+
| DOTS | | DOTS |
+--------------+ +--------------+
| CoAP | | CoAP |
+--------------+ +--------------+
| TLS | DTLS | | TLS | DTLS |
+--------------+ +--------------+
| TCP | UDP | | TCP | UDP |
+--------------+ +--------------+
| IP | | IP |
+--------------+ +--------------+
Figure 4: Abstract Layering of DOTS signal channel over CoAP over Figure 3: Abstract Layering of DOTS signal channel over CoAP over
(D)TLS (D)TLS
The signal channel is initiated by the DOTS client. Once the signal By default, DOTS signal channel MUST run over port number TBD as
channel is established, the DOTS agents periodically send heartbeats defined in Section 10.1, for both UDP and TCP, unless the DOTS server
to keep the channel active. At any time, the DOTS client may send a has mutual agreement with its DOTS clients to use a port other than
mitigation request message to the DOTS server over the active TBD for DOTS signal channel, or DOTS clients supports means to
channel. While mitigation is active, due to the higher likelihood of dynamically discover the ports used by their DOTS servers. In order
packet loss during a DDoS attack, the DOTS server periodically sends to use a distinct port number (vs. TBD), DOTS clients and servers
status messages to the client, including basic mitigation feedback should support a configurable parameter to supply the port number to
details. Mitigation remains active until the DOTS client explicitly use.
terminates mitigation, or the mitigation lifetime expires.
Messages exchanged between DOTS client and server are serialized The signal channel is initiated by the DOTS client (Section 4.4).
Once the signal channel is established, the DOTS agents periodically
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
server over the active channel. While mitigation is active, due to
the higher likelihood of packet loss during a DDoS attack, the DOTS
server periodically sends status messages to the client, including
basic mitigation feedback details. Mitigation remains active until
the DOTS client explicitly terminates mitigation, or the mitigation
lifetime expires.
DOTS signaling can happen with DTLS [RFC6347] over UDP and TLS
[RFC5246] over TCP. Likewise, requests may be sent using IPv4 or
IPv6 transfer capabilities. A Happy Eyeballs procedure for DOTS
signal channel is specified in Section 4.3.
Messages exchanged between DOTS clients and servers are serialized
using Concise Binary Object Representation (CBOR) [RFC7049], CBOR is using Concise Binary Object Representation (CBOR) [RFC7049], CBOR is
a binary encoding designed for small code and message size. CBOR a binary encoding designed for small code and message size. CBOR
encoded payloads are used to convey signal channel specific payload encoded payloads are used to convey signal channel specific payload
messages that convey request parameters and response information such messages that convey request parameters and response information such
as errors. This specification uses the encoding rules defined in as errors. This specification uses the encoding rules defined in
[I-D.ietf-core-yang-cbor] for representing mitigation scope and DOTS [I-D.ietf-core-yang-cbor] for representing mitigation scope and DOTS
signal channel session configuration data defined using YANG signal channel session configuration data defined using YANG
(Section 5.2) as CBOR data. (Section 5) as CBOR data.
In order to prevent fragmentation, DOTS agents must follow the
recommendations in Section 4.6 of [RFC7252]. Refer to Section 7.2
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.
5.2. DOTS Signal YANG Module 4. DOTS Signal Channel: Messages & Behaviors
This document defines a YANG [RFC6020] module for mitigation scope
and DOTS signal channel session configuration data.
5.2.1. Mitigation Request YANG Module Tree Structure
This document defines the YANG module "ietf-dots-signal", which has
the following tree structure:
module: ietf-dots-signal
+--rw mitigation-scope
+--rw client-identifier* binary
+--rw scope* [mitigation-id]
+--rw mitigation-id int32
+--rw target-ip* inet:ip-address
+--rw target-prefix* inet:ip-prefix
+--rw target-port-range* [lower-port upper-port]
| +--rw lower-port inet:port-number
| +--rw upper-port inet:port-number
+--rw target-protocol* uint8
+--rw fqdn* inet:domain-name
+--rw uri* inet:uri
+--rw alias-name* string
+--rw lifetime? int32
5.2.2. Mitigation Request YANG Module
<CODE BEGINS> file "ietf-dots-signal@2017-10-04.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";
}
organization "IETF DOTS Working Group";
contact
"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
"This module contains YANG definition for DOTS
signal sent by the DOTS client to the DOTS server.
Copyright (c) 2017 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
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).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2017-10-04 {
description
"Add units and fix some nits.";
reference
"-05";
}
revision 2017-08-03 {
reference
"https://tools.ietf.org/html/draft-reddy-dots-signal-channel";
}
container mitigation-scope {
description
"Top level container for a mitigation request.";
leaf-list client-identifier {
type binary;
description
"A client identifier conveyed by a DOTS gateway
to a remote DOTS server.";
}
list scope {
key mitigation-id;
description "Identifier for the mitigation request.";
leaf mitigation-id {
type int32;
description "Mitigation request identifier.";
}
leaf-list target-ip {
type inet:ip-address;
description
"IPv4 or IPv6 address identifying the target.";
}
leaf-list target-prefix {
type inet:ip-prefix;
description
"IPv4 or IPv6 prefix identifying the target.";
}
list target-port-range {
key "lower-port upper-port";
description "Port range. When only lower-port is present,
it represents a single port.";
leaf lower-port {
type inet:port-number;
mandatory true;
description "Lower port number.";
}
leaf upper-port {
type inet:port-number;
must ". >= ../lower-port" {
error-message
"The upper port number must be greater than or
equal to lower port number.";
}
description "Upper port number.";
}
}
leaf-list target-protocol {
type uint8;
description "Identifies the target protocol number.";
}
leaf-list fqdn {
type inet:domain-name;
description "FQDN";
}
leaf-list uri {
type inet:uri;
description "URI";
}
leaf-list alias-name {
type string;
description "alias name";
}
leaf lifetime {
type int32;
units "seconds";
default 3600;
description
"Indicates the lifetime of the mitigation request.";
}
}
}
}
<CODE ENDS>
5.2.3. Session Configuration YANG Module Tree Structure
This document defines the YANG module "ietf-dots-signal-config",
which has the following structure:
module: ietf-dots-signal-config
+--rw signal-config
+--rw session-id? int32
+--rw heartbeat-interval? int16
+--rw missing-hb-allowed? int16
+--rw max-retransmit? int16
+--rw ack-timeout? int16
+--rw ack-random-factor? decimal64
+--rw trigger-mitigation? boolean
5.2.4. Session Configuration YANG Module
<CODE BEGINS> file "ietf-dots-signal-config@2017-10-04.yang"
module ietf-dots-signal-config {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-signal-config";
prefix "config";
organization "IETF DOTS Working Group";
contact
"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
"This module contains YANG definition for DOTS
signal channel session configuration.
Copyright (c) 2017 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
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).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2017-10-04 {
description
"Add units/defaults and fix some nits.";
reference
"-05";
}
revision 2016-11-28 {
reference
"https://tools.ietf.org/html/draft-reddy-dots-signal-channel";
}
container signal-config {
description "Top level container for DOTS signal channel session
configuration.";
leaf session-id {
type int32;
description "An identifier for the DOTS signal channel
session configuration data.";
}
leaf heartbeat-interval {
type int16;
units "seconds";
default 30;
description
"DOTS agents regularly send heartbeats to each other
after mutual authentication in order to keep
the DOTS signal channel open.";
}
leaf missing-hb-allowed { 4.1. DOTS Server(s) Discovery
type int16;
default 5;
description This document assumes that DOTS clients are provisioned with the
"Maximum number of missing heartbeats allowed."; reachability information of their DOTS server(s) using a variety of
} means (e.g., local configuration, or dynamic means such as DHCP).
These means are out of scope of this document.
leaf max-retransmit { Likewise, it is out of scope of this document to specify the behavior
type int16; to follow by a DOTS client to place its requests (e.g., contact all
default 3; servers, select one server among the list) when multiple DOTS servers
are provisioned.
description 4.2. CoAP URIs
"Maximum number of retransmissions of a
Confirmable message.";
}
leaf ack-timeout { The DOTS server MUST support the use of the path-prefix of "/.well-
type int16; known/" as defined in [RFC5785] and the registered name of "dots".
units "seconds"; Each DOTS operation is indicated by a path-suffix that indicates the
default 2; intended operation.
description +-----------------------+----------------+-------------+
"Initial retransmission timeout value."; | Operation | Operation path | Details |
} +-----------------------+----------------+-------------+
| Mitigation | /v1/mitigate | Section 4.4 |
+-----------------------+----------------+-------------+
| Session configuration | /v1/config | Section 4.5 |
+-----------------------+----------------+-------------+
leaf ack-random-factor { Table 1: Operations and their corresponding URIs
type decimal64 {
fraction-digits 2;
}
default 1.5; 4.3. Happy Eyeballs for DOTS Signal Channel
description DOTS signaling can happen with DTLS over UDP and TLS over TCP. A
"Random factor used to influence the timing of DOTS client can use DNS to determine the IP address(es) of a DOTS
retransmissions"; server or a DOTS client may be provided with the list of DOTS server
} IP addresses. The DOTS client MUST know a DOTS server's domain name;
leaf trigger-mitigation { hard-coding the domain name of the DOTS server into software is NOT
type boolean; RECOMMENDED in case the domain name is not valid or needs to change
default true; for legal or other reasons. The DOTS client performs A and/or AAAA
record lookup of the domain name and the result will be a list of IP
addresses, each of which can be used to contact the DOTS server using
UDP and TCP.
description If an IPv4 path to reach a DOTS server is found, but the DOTS
"If false, then mitigation is triggered server's IPv6 path is not working, a dual-stack DOTS client can
only when the DOTS server channel session is lost"; experience a significant connection delay compared to an IPv4-only
} DOTS client. The other problem is that if a middlebox between the
} DOTS client and DOTS server is configured to block UDP, the DOTS
} client will fail to establish a DTLS session with the DOTS server and
<CODE ENDS> will, then, have to fall back to TLS over TCP incurring significant
connection delays. [I-D.ietf-dots-requirements] discusses that DOTS
client and server will have to support both connectionless and
connection-oriented protocols.
5.3. CoAP URIs 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,
UDP over IPv4, TCP over IPv6, and finally TCP over IPv4, which
adheres to address preference order [RFC6724] and the DOTS preference
that UDP be used over TCP (to avoid TCP's head of line blocking).
The DOTS server MUST support the use of the path-prefix of "/.well- DOTS client DOTS server
known/" as defined in [RFC5785] and the registered name of "dots". | |
Each DOTS operation is indicated by a path-suffix that indicates the |--DTLS ClientHello, IPv6 ---->X |
intended operation. |--TCP SYN, IPv6-------------->X |
|--DTLS ClientHello, IPv4 ---->X |
|--TCP SYN, IPv4----------------------------------------->|
|--DTLS ClientHello, IPv6 ---->X |
|--TCP SYN, IPv6-------------->X |
|<-TCP SYNACK---------------------------------------------|
|--DTLS ClientHello, IPv4 ---->X |
|--TCP ACK----------------------------------------------->|
|<------------Establish TLS Session---------------------->|
|----------------DOTS signal----------------------------->|
| |
+------------------------+-----------------+-------------------+ Figure 4: DOTS Happy Eyeballs
| Operation |Operation path | Details |
+========================+=================+===================+
| Mitigation | /v1/mitigate | Section 5.4 |
| | | |
+------------------------+-----------------+-------------------+
| Session configuration | /v1/config | Section 5.5 |
| | | |
+------------------------+-----------------+-------------------+
Figure 5: Operations and their corresponding URIs: 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
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
because there is no long delay before using IPv4 and TCP. The DOTS
client repeats the mechanism to discover if DOTS signaling with DTLS
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
SHOULD NOT be done more frequently than every 24 hours and MUST NOT
be done more frequently than every 5 minutes.
5.4. Mitigation Request 4.4. DOTS Mitigation Methods
The following methods are used to request or withdraw mitigation The following methods are used by a DOTS client to request, withdraw,
requests: or retrieve the status of mitigation requests:
PUT: DOTS clients use the PUT method to request mitigation PUT: DOTS clients use the PUT method to request mitigation from a
(Section 5.4.1). During active mitigation, DOTS clients may use DOTS server (Section 4.4.1). During active mitigation, DOTS
PUT requests to convey mitigation efficacy updates to the DOTS clients may use PUT requests to convey mitigation efficacy updates
server (Section 5.4.4). to the DOTS server (Section 4.4.4).
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 the DOTS server (Section 5.4.2). mitigation from the DOTS server (Section 4.4.2).
GET: DOTS clients may use the GET method to subscribe to DOTS server GET: DOTS clients may use the GET method to subscribe to DOTS server
status messages, or to retrieve the list of existing mitigations status messages, or to retrieve the list of existing mitigations
(Section 5.4.3). (Section 4.4.3).
Mitigation request and response messages are marked as Non- Mitigation request and response messages are marked as Non-
confirmable messages. DOTS agents SHOULD follow the data confirmable messages. DOTS agents SHOULD follow the data
transmission guidelines discussed in Section 3.1.3 of [RFC8085] and transmission guidelines discussed in Section 3.1.3 of [RFC8085] and
control transmission behavior by not sending on average more than one control transmission behavior by not sending on average more than one
UDP datagram per RTT to the peer DOTS agent. UDP datagram per RTT to the peer DOTS agent.
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 and if the DOTS client cannot maintain a RTT estimate then 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 when possible
(case 2 in Section 3.1.3 of [RFC8085]). (case 2 in Section 3.1.3 of [RFC8085]).
5.4.1. Requesting mitigation 4.4.1. Request Mitigation
When a DOTS client requires mitigation for any reason, the DOTS When a DOTS client requires mitigation for any reason, the DOTS
client uses CoAP PUT method to send a mitigation request to the DOTS client uses CoAP PUT method to send a mitigation request to the DOTS
server (Figure 6, illustrated in JSON diagnostic notation). The DOTS server(s) (Figure 5, illustrated in JSON diagnostic notation). 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"
skipping to change at page 17, line 50 skipping to change at page 11, line 50
], ],
"alias-name": [ "alias-name": [
"string" "string"
], ],
"lifetime": integer "lifetime": integer
} }
] ]
} }
} }
Figure 6: PUT to convey DOTS signals Figure 5: PUT to convey DOTS signals
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 final DOTS server
to accept mitigation requests with scopes which the DOTS client is to 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 no probability that the
skipping to change at page 21, line 15 skipping to change at page 15, line 15
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 both alias-name and other parameters identifying the target resources
(such as, 'target-ip', 'target-prefix', 'target-port-range', 'fqdn', (such as, 'target-ip', 'target-prefix', 'target-port-range', 'fqdn',
or 'uri'), then the DOTS server appends the parameter values in or 'uri'), then the DOTS server appends the parameter values in
'alias-name' with the corresponding parameter values in 'target-ip', 'alias-name' with the corresponding parameter values in 'target-ip',
'target-prefix', 'target-port-range', 'fqdn', or 'uri'. 'target-prefix', 'target-port-range', 'fqdn', or 'uri'.
Figure 7 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 on the servers 2001:db8:6401::1 and 2001:db8:6401::2 are
being attacked (illustrated in JSON diagnostic notation). being attacked (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"
skipping to change at page 22, line 44 skipping to change at page 16, line 44
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)
19 1F90 # unsigned(8080) 19 1F90 # unsigned(8080)
08 # unsigned(8) 08 # unsigned(8)
81 # array(1) 81 # array(1)
06 # unsigned(6) 06 # unsigned(6)
Figure 7: PUT for DOTS signal Figure 6: PUT for DOTS signal
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. Figure 8 shows a PUT codes are some sort of invalid requests (client errors). COAP 5.xx
response for CoAP 2.xx response codes. codes are returned if the DOTS server has erred or is currently
unavailable to provide mitigation in response to the mitigation
request from the DOTS client.
Figure 7 shows an example of a PUT request that is successfully
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": integer,
"lifetime": integer "lifetime": integer
} }
] ]
} }
} }
Figure 8: 2.xx response body Figure 7: 2.xx response body
COAP 5.xx codes are returned if the DOTS server has erred or is
currently unavailable to provide mitigation in response to the
mitigation request from the DOTS client.
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, then the conveyed in the PUT request in its configuration data, then the
server MAY accept the mitigation request by sending back a 2.01 server MAY accept the mitigation request by sending back a 2.01
(Created) response to the DOTS client; the DOTS server will (Created) response to the DOTS client; the DOTS server will
consequently try to mitigate the attack. consequently try to mitigate 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, then the server MAY in the PUT request in its configuration data, then the server MAY
update the mitigation request, and a 2.04 (Changed) response is update the mitigation request, and a 2.04 (Changed) response is
skipping to change at page 24, line 5 skipping to change at page 18, line 5
request by sending a new PUT request. The PUT request MUST use the request by sending a new PUT request. The PUT request MUST use the
same 'mitigation-id' value, and MUST repeat all the other parameters same 'mitigation-id' value, and MUST repeat all the other parameters
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.
5.4.2. Withdraw a DOTS Signal 4.4.2. Withdraw a Mitigation
A DELETE request is used to withdraw a DOTS signal from a DOTS server A DELETE request is used to withdraw a DOTS mitigation request from a
(Figure 9). DOTS server (Figure 8).
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": {
skipping to change at page 24, line 30 skipping to change at page 18, line 30
"string" "string"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": integer "mitigation-id": integer
} }
] ]
} }
} }
Figure 9: Withdraw DOTS signal Figure 8: Withdraw DOTS signal
The DOTS server immediately acknowledges a DOTS client's request to The DOTS server immediately acknowledges a DOTS client's request to
withdraw the DOTS signal using 2.02 (Deleted) response code with no withdraw the DOTS signal using 2.02 (Deleted) response code with no
response payload. A 2.02 (Deleted) Response Code is returned even if response payload. A 2.02 (Deleted) Response Code is returned even if
the 'mitigation-id' parameter value conveyed in the DELETE request the 'mitigation-id' parameter value conveyed in the DELETE request
does not exist in its configuration data before the request. does not exist in its 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, then to protect
against route or DNS flapping caused by a client rapidly toggling against route or DNS flapping caused by a client rapidly toggling
skipping to change at page 25, line 9 skipping to change at page 19, line 9
SHOULD be set by default to 120 seconds. If the client requests SHOULD be set by default to 120 seconds. If the client requests
mitigation again before the initial active-but-terminating period mitigation again before the initial active-but-terminating period
elapses, the DOTS server MAY exponentially increase the active-but- elapses, the DOTS server MAY exponentially increase the active-but-
terminating period up to a maximum of 300 seconds (5 minutes). After terminating period up to a maximum of 300 seconds (5 minutes). After
the active-but-terminating period elapses, the DOTS server MUST treat the active-but-terminating period elapses, the DOTS server MUST treat
the mitigation as terminated, as the DOTS client is no longer 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 ceases incurring cost at this point.
5.4.3. Retrieving a DOTS Signal 4.4.3. Retrieve Information Related to a Mitigation
A GET request is used to retrieve information (including status) of a A GET request is used to retrieve information (including status) of a
DOTS signal from a DOTS server (Figure 10). If the DOTS server does DOTS mitigation from a DOTS server (Figure 9). If the DOTS server
not find the 'mitigation-id' parameter value conveyed in the GET does not find the 'mitigation-id' parameter value conveyed in the GET
request in its configuration data, then it responds with a 4.04 (Not request in its configuration data, then it responds with a 4.04 (Not
Found) error response code. The 'c' (content) parameter and its Found) error response code. The 'c' (content) parameter and its
permitted values defined in [I-D.ietf-core-comi] can be used to permitted values defined in [I-D.ietf-core-comi] can be used to
retrieve non-configuration data (attack mitigation status) or retrieve non-configuration data (attack mitigation status) or
configuration data or both. The DOTS server SHOULD support this configuration data or both. The DOTS server SHOULD support this
optional filtering capability but can safely ignore it if not optional filtering capability but can safely ignore it if not
supported. supported.
The examples below assume the default of "c=a". The examples depicted in Figure 9 assume the default of "c=a".
1) To retrieve all DOTS signals signaled by the DOTS client. 1) To retrieve all DOTS signals signaled by the DOTS client.
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
skipping to change at page 26, line 47 skipping to change at page 20, line 47
"string" "string"
], ],
"scope": [ "scope": [
{ {
"mitigation-id": integer "mitigation-id": integer
} }
] ]
} }
} }
Figure 10: GET to retrieve the rules Figure 9: GET to retrieve the rules
Figure 11 shows a response example of all the active mitigation Figure 10 shows a response example of all the active mitigation
requests associated with the DOTS client on the DOTS server and the requests associated with the DOTS client on the DOTS server and the
mitigation status of each mitigation request. mitigation 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": [
skipping to change at page 27, line 38 skipping to change at page 21, line 38
"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 10: Response body
The mitigation status parameters are described below. The mitigation status parameters are described below.
lifetime: The remaining lifetime of the mitigation request in lifetime: The remaining lifetime of the mitigation request in
seconds. seconds.
mitigation-start: Mitigation start time is represented in seconds mitigation-start: Mitigation start time is represented 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.
skipping to change at page 28, line 22 skipping to change at page 22, line 22
request since the attack mitigation is triggered. This is an request since the attack mitigation is triggered. This is an
optional attribute. optional attribute.
pps-dropped: The average dropped packets per second for the pps-dropped: The average dropped packets per second for the
mitigation request since the attack mitigation is triggered. This mitigation request since the attack mitigation is triggered. This
SHOULD be a five-minute average. This is an optional attribute. SHOULD be a five-minute average. This is an optional attribute.
status: Status of attack mitigation. The 'status' parameter is a status: Status of attack mitigation. The 'status' parameter is a
mandatory attribute. mandatory attribute.
The various possible values of 'status' parameter are explained The various possible values of 'status' parameter are explained in
below: Table 2.
/--------------------+---------------------------------------------------\ +-----------+-------------------------------------------------------+
| Parameter value | Description | | Parameter | Description |
+--------------------+---------------------------------------------------+ | value | |
| 1 | Attack mitigation is in progress | +-----------+-------------------------------------------------------+
| | (e.g., changing the network path to re-route the | | 1 | Attack mitigation is in progress (e.g., changing the |
| | inbound traffic to DOTS mitigator). | | | network path to re-route the inbound traffic to DOTS |
+--------------------+---------------------------------------------------+ | | mitigator). |
| 2 | Attack is successfully mitigated | +-----------+-------------------------------------------------------+
| | (e.g., traffic is redirected to a DDOS mitigator | | 2 | Attack is successfully mitigated (e.g., traffic is |
| | and attack traffic is dropped). | | | redirected to a DDOS mitigator and attack traffic is |
+--------------------+---------------------------------------------------+ | | dropped). |
| 3 | Attack has stopped and the DOTS client | +-----------+-------------------------------------------------------+
| | can withdraw the mitigation request. | | 3 | Attack has stopped and the DOTS client an withdraw |
+--------------------+---------------------------------------------------+ | | the mitigation request. |
| 4 | Attack has exceeded the mitigation provider | +-----------+-------------------------------------------------------+
| | capability. | | 4 | Attack has exceeded the mitigation provider |
+--------------------+---------------------------------------------------+ | | capability. |
| 5 | DOTS client has withdrawn the mitigation request | +-----------+-------------------------------------------------------+
| | and the mitigation is active but terminating. | | 5 | DOTS client has withdrawn the mitigation request and |
\--------------------+---------------------------------------------------/ | | the mitigation is active but terminating. |
+-----------+-------------------------------------------------------+
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. Unidirectional notifications within the bidirectional signal
channel allows unsolicited message delivery, enabling asynchronous 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 then it SHOULD NOT the DOTS server cannot maintain a RTT estimate, it SHOULD NOT send
send more than one unsolicited notification every 3 seconds, and more than one unsolicited notification every 3 seconds, and SHOULD
SHOULD use an even less aggressive rate when possible (case 2 in use an even less aggressive rate when possible (case 2 in
Section 3.1.3 of [RFC8085]). A DOTS client that is no longer Section 3.1.3 of [RFC8085]).
interested in receiving notifications from the DOTS server can simply
"forget" the observation. When the DOTS server then sends the next
notification, the DOTS client will not recognize the token in the
message and thus will return a Reset message. This causes the DOTS
server to remove the associated entry. Alternatively, the DOTS
client can explicitly deregister by issuing a GET request that has
the Token field set to the token of the observation to be cancelled
and includes an Observe Option with the value set to 1 (deregister).
DOTS Client DOTS Server A DOTS client that is no longer interested in receiving notifications
| | from the DOTS server can simply "forget" the observation. When the
| GET /<mitigation-id number> | DOTS server then sends the next notification, the DOTS client will
| Token: 0x4a | Registration not recognize the token in the message and thus will return a Reset
| Observe: 0 | message. This causes the DOTS server to remove the associated entry.
+------------------------------>| Alternatively, the DOTS client can explicitly deregister by issuing a
| | GET request that has the Token field set to the token of the
| 2.05 Content | observation to be cancelled and includes an Observe Option with the
| Token: 0x4a | Notification of value set to '1' (deregister).
| Observe: 12 | the current state
| status: "mitigation |
| in progress" |
|<------------------------------+
| 2.05 Content |
| Token: 0x4a | Notification upon
| Observe: 44 | a state change
| status: "mitigation |
| complete" |
|<------------------------------+
| 2.05 Content |
| Token: 0x4a | Notification upon
| Observe: 60 | a state change
| status: "attack stopped" |
|<------------------------------+
| |
Figure 12: Notifications of attack mitigation status Figure 11 shows an example of a DOTS client requesting a DOTS server
to send notifications related a given mitigation request.
5.4.3.1. Mitigation Status DOTS Client DOTS Server
| |
| GET /<mitigation-id number> |
| Token: 0x4a | Registration
| Observe: 0 |
+------------------------------>|
| |
| 2.05 Content |
| Token: 0x4a | Notification of
| Observe: 12 | the current state
| status: "mitigation |
| in progress" |
|<------------------------------+
| 2.05 Content |
| Token: 0x4a | Notification upon
| Observe: 44 | a state change
| status: "mitigation |
| complete" |
|<------------------------------+
| 2.05 Content |
| Token: 0x4a | Notification upon
| Observe: 60 | a state change
| status: "attack stopped" |
|<------------------------------+
| |
Figure 11: Notifications of attack mitigation status
4.4.3.1. Mitigation Status
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 for the mitigation-id. mitigation request by issuing a DELETE 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 from the DOTS
server and not the fact that it has recognized, using its own means, server and not the fact that it has recognized, using its own means,
that the attack has been mitigated. This ensures that the DOTS that the attack has been mitigated. This ensures that the DOTS
client does not recall a mitigation request in a premature fashion client does not recall a mitigation request in a premature fashion
because it is possible that the DOTS client does not sense the DDOS because it is possible that the DOTS client does not sense the DDOS
attack on its resources but the DOTS server could be actively attack on its resources but the DOTS server could be actively
mitigating the attack and the attack is not completely averted. mitigating the attack and the attack is not completely averted.
5.4.4. Efficacy Update from DOTS Client 4.4.4. 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 efficacy updates to the relevant DOTS server. A PUT request
(Figure 13) is used to convey the mitigation efficacy update to the (Figure 12) is used to convey the mitigation efficacy update to the
DOTS server. 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 5.4.1) unchanged apart request to convey the DOTS signal (Section 4.4.1) unchanged apart
from the lifetime parameter value. If this is not the case, the DOTS from the lifetime parameter value. If this is not the case, the DOTS
server MUST reject the request with a 4.02 error response code. server MUST reject the request with a 4.02 error response code.
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
skipping to change at page 31, line 48 skipping to change at page 26, line 48
"alias-name": [ "alias-name": [
"string" "string"
], ],
"lifetime": integer, "lifetime": integer,
"attack-status": integer "attack-status": integer
} }
] ]
} }
} }
Figure 13: Efficacy Update Figure 12: Efficacy Update
The 'attack-status' parameter is a mandatory attribute when doing a The 'attack-status' parameter is a mandatory attribute when doing a
efficacy update. The various possible values contained in the efficacy update. The various possible values contained in the
'attack-status' parameter are described below: 'attack-status' parameter are described in Table 3.
/--------------------+------------------------------------------------------\ +-----------+-------------------------------------------------------+
| Parameter value | Description | | Parameter | Description |
+--------------------+------------------------------------------------------+ | value | |
| 1 | DOTS client determines that it is still under attack.| +-----------+-------------------------------------------------------+
+--------------------+------------------------------------------------------+ | 1 | The DOTS client determines that it is still under |
| 2 | DOTS client determines that the attack is | | | attack. |
| | successfully mitigated | +-----------+-------------------------------------------------------+
| | (e.g., attack traffic is not seen). | | 2 | The DOTS client determines that the attack is |
\--------------------+------------------------------------------------------/ | | successfully mitigated (e.g., attack traffic is not |
| | seen). |
+-----------+-------------------------------------------------------+
Table 3: Values of 'attack-status' parameter
The DOTS server indicates the result of processing a PUT request The DOTS server indicates the result of processing a PUT request
using CoAP response codes. The response code 2.04 (Changed) is using CoAP response codes. The response code 2.04 (Changed) is
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.
5.5. 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: DOTS agents regularly send heartbeats (CoAP
Ping/Pong) to each other after mutual authentication in order to Ping/Pong) to each other after mutual authentication in order to
keep the DOTS signal channel open, heartbeat messages are keep the DOTS signal channel open, heartbeat messages are
exchanged between the DOTS agents every heartbeat-interval exchanged between the DOTS agents every heartbeat-interval
seconds to detect the current status of the DOTS signal channel seconds to detect the current status of the DOTS signal channel
skipping to change at page 33, line 14 skipping to change at page 28, line 17
Section 4.8 of [RFC7252]. Reliability is provided to the responses Section 4.8 of [RFC7252]. Reliability is provided to the responses
by marking them as Confirmable (CON) messages. The DOTS server can by marking them as Confirmable (CON) messages. The DOTS server can
either piggyback the response in the acknowledgement message or if either piggyback the response in the acknowledgement message or if
the DOTS server is not able to respond immediately to a request the DOTS server is not able to respond immediately to a request
carried in a Confirmable message, it simply responds with an Empty carried in a Confirmable message, it simply responds with an Empty
Acknowledgement message so that the DOTS client can stop Acknowledgement message so that the DOTS client can stop
retransmitting the request. Empty Acknowledgement message is retransmitting the request. Empty Acknowledgement message is
explained in Section 2.2 of [RFC7252]. When the response is ready, explained in Section 2.2 of [RFC7252]. When the response is ready,
the server sends it in a new Confirmable message which then in turn the server sends it in a new Confirmable message which then in turn
needs to be acknowledged by the DOTS client (see Sections 5.2.1 and needs to be acknowledged by the DOTS client (see Sections 5.2.1 and
Sections 5.2.2 of [RFC7252]). Requests and responses exchanged 5.2.2 of [RFC7252]). Requests and responses exchanged between DOTS
between DOTS agents during peacetime are marked as Confirmable agents during peacetime are marked as Confirmable messages.
messages.
Implementation Note: A DOTS client that receives a response in a CON Implementation Note: A DOTS client that receives a response in a CON
message may want to clean up the message state right after sending message may want to clean up the message state right after sending
the ACK. If that ACK is lost and the DOTS server retransmits the the ACK. If that ACK is lost and the DOTS server retransmits the
CON, the DOTS client may no longer have any state to which to CON, the DOTS client may no longer have any state to which to
correlate this response, making the retransmission an unexpected correlate this response, making the retransmission an unexpected
message; the DOTS client will send a Reset message so it does not message; the DOTS client will send a Reset message so it does not
receive any more retransmissions. This behavior is normal and not an receive any more retransmissions. This behavior is normal and not an
indication of an error (see Section 5.3.2 of [RFC7252] for more indication of an error (see Section 5.3.2 of [RFC7252] for more
details). details).
5.5.1. 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 and current configuration
parameters on the DOTS server for DOTS signal channel session parameters on the DOTS server for DOTS signal channel session
configuration. Figure 14 shows how to obtain acceptable configuration. Figure 13 shows how to obtain acceptable
configuration parameters for the server. 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 14: GET to retrieve configuration Figure 13: 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.
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"heartbeat-interval": { "heartbeat-interval": {
"CurrentValue": integer, "CurrentValue": integer,
"MinValue": integer, "MinValue": integer,
"MaxValue" : integer, "MaxValue" : integer,
skipping to change at page 34, line 37 skipping to change at page 29, line 37
"ack-random-factor": { "ack-random-factor": {
"CurrentValue": number, "CurrentValue": number,
"MinValue": number, "MinValue": number,
"MaxValue" : number, "MaxValue" : number,
}, },
"trigger-mitigation": { "trigger-mitigation": {
"CurrentValue": boolean, "CurrentValue": boolean,
} }
} }
Figure 15: GET response body Figure 14: GET response body
Figure 16 shows an example of acceptable and current configuration Figure 15 shows an example of acceptable and current configuration
parameters on the DOTS server for DOTS signal channel session parameters on the DOTS server for DOTS signal channel session
configuration. configuration.
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
"heartbeat-interval": { "heartbeat-interval": {
"CurrentValue": 30, "CurrentValue": 30,
"MinValue": 15, "MinValue": 15,
"MaxValue" : 240, "MaxValue" : 240,
}, },
skipping to change at page 35, line 37 skipping to change at page 30, line 37
"ack-random-factor": { "ack-random-factor": {
"CurrentValue": 1.5, "CurrentValue": 1.5,
"MinValue": 1.1, "MinValue": 1.1,
"MaxValue" : 4.0, "MaxValue" : 4.0,
}, },
"trigger-mitigation": { "trigger-mitigation": {
"CurrentValue": true, "CurrentValue": true,
} }
} }
Figure 16: configuration response body Figure 15: Configuration response body
5.5.2. 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
signaling channel (e.g., heartbeat interval, maximum signal channel (e.g., heartbeat interval, maximum retransmissions).
retransmissions). Message transmission parameters for CoAP are Message transmission parameters for CoAP are defined in Section 4.8
defined in Section 4.8 of [RFC7252]. The RECOMMENDED values of of [RFC7252]. The RECOMMENDED values of transmission parameter
transmission parameter values are ack_timeout (2 seconds), max- values are ack_timeout (2 seconds), max-retransmit (3), ack-random-
retransmit (3), ack-random-factor (1.5). In addition to those factor (1.5). In addition to those parameters, the RECOMMENDED
parameters, the RECOMMENDED specific DOTS transmission parameter specific DOTS transmission parameter values are heartbeat-interval
values are heartbeat-interval (30 seconds) and missing-hb-allowed (30 seconds) and missing-hb-allowed (5).
(5).
Note: heartbeat-interval should be tweaked to also assist DOTS Note: heartbeat-interval should be tweaked to also assist DOTS
messages for NAT traversal (SIG-010 of messages for NAT traversal (SIG-010 of
[I-D.ietf-dots-requirements]). According to [RFC8085], keepalive [I-D.ietf-dots-requirements]). According to [RFC8085], keepalive
messages must not be sent more frequently than once every 15 messages must not be sent more frequently than once every 15
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
skipping to change at page 36, line 41 skipping to change at page 31, line 39
signal channel session is disconnected. A DOTS client MUST NOT signal channel session is disconnected. A DOTS client MUST NOT
transmit a "CoAP ping" while waiting for the previous "CoAP ping" transmit a "CoAP ping" while waiting for the previous "CoAP ping"
response from 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 signaling 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.
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: "config" Uri-Path: "config"
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
skipping to change at page 37, line 24 skipping to change at page 32, line 24
"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
} }
} }
Figure 17: PUT to convey the DOTS signal channel session Figure 16: PUT to convey the DOTS signal channel session
configuration data. configuration data.
The parameters are described below: The parameters 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. This is a any assumption about how this identifier is generated. This is a
mandatory attribute. mandatory attribute.
skipping to change at page 38, line 24 skipping to change at page 33, line 24
DOTS server can detect that the DOTS session is lost. The default DOTS server can detect that the DOTS session is lost. The default
value of the parameter is 'true'. This is an optional attribute. value of the parameter is 'true'. This is an optional attribute.
In the PUT request at least one of the attributes heartbeat-interval, In the PUT request at least one of the attributes heartbeat-interval,
missing-hb-allowed, max-retransmit, ack-timeout, ack-random-factor, missing-hb-allowed, max-retransmit, ack-timeout, ack-random-factor,
and trigger-mitigation MUST be present. The PUT request with higher and trigger-mitigation MUST be present. The PUT request with higher
numeric session-id value over-rides the DOTS signal channel session numeric session-id value over-rides the DOTS signal channel session
configuration data installed by a PUT request with a lower numeric configuration data installed by a PUT request with a lower numeric
session-id value. session-id value.
Figure 18 shows a PUT request example to convey the configuration Figure 17 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"
Content-Format: "application/cbor" Content-Format: "application/cbor"
{ {
skipping to change at page 38, line 46 skipping to change at page 33, line 46
"session-id": 1234534333242, "session-id": 1234534333242,
"heartbeat-interval": 91, "heartbeat-interval": 91,
"missing-hb-allowed": 3, "missing-hb-allowed": 3,
"max-retransmit": 7, "max-retransmit": 7,
"ack-timeout": 5, "ack-timeout": 5,
"ack-random-factor": 1.5, "ack-random-factor": 1.5,
"trigger-mitigation": false "trigger-mitigation": false
} }
} }
Figure 18: PUT to convey the configuration parameters Figure 17: PUT to convey the configuration parameters
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: using CoAP response codes:
o If the DOTS server finds the 'session-id' parameter value conveyed o If the DOTS server finds the 'session-id' parameter value conveyed
in the PUT request in its configuration data and if the DOTS in the PUT request in its configuration data and if the DOTS
server has accepted the updated configuration parameters, then server has accepted the updated configuration parameters, then
2.04 (Changed) code is returned in the response. 2.04 (Changed) code is returned in the response.
o If the DOTS server does not find the 'session-id' parameter value o If the DOTS server does not find the 'session-id' parameter value
skipping to change at page 39, line 24 skipping to change at page 34, line 24
o If the request contains one or more invalid or unknown parameters, o If the request contains one or more invalid or unknown parameters,
then 4.02 (Invalid query) code is returned in the response. then 4.02 (Invalid query) code is returned in the response.
o Response code 4.22 (Unprocessable Entity) is returned in the o Response code 4.22 (Unprocessable Entity) is returned in the
response, if any of the heartbeat-interval, missing-hb-allowed, response, if any of the heartbeat-interval, missing-hb-allowed,
max-retransmit, target-protocol, ack-timeout, and ack-random- max-retransmit, target-protocol, ack-timeout, and ack-random-
factor attribute values are not acceptable to the DOTS server. factor attribute values are not acceptable to the DOTS server.
Upon receipt of the 4.22 error response code, the DOTS client Upon receipt of the 4.22 error response code, the DOTS client
should request the maximum and minimum attribute values acceptable should request the maximum and minimum attribute values acceptable
to the DOTS server (Section 5.5.1). The DOTS client may re-try to the DOTS server (Section 4.5.1). The DOTS client may re-try
and send the PUT request with updated attribute values acceptable and send the PUT request with updated attribute values acceptable
to the DOTS server. to the DOTS server.
5.5.3. Delete DOTS Signal Channel Session Configuration 4.5.3. Delete DOTS Signal Channel Session Configuration
A DELETE request is used to delete the installed DOTS signal channel A DELETE request is used to delete the installed DOTS signal channel
session configuration data (Figure 19). session configuration data (Figure 18).
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: "config" Uri-Path: "config"
Content-Format: "application/cbor" Content-Format: "application/cbor"
Figure 19: DELETE configuration Figure 18: DELETE configuration
The DOTS server resets the DOTS signal channel session configuration The DOTS server resets the DOTS signal channel session configuration
back to the default values and acknowledges a DOTS client's request back to the default values and acknowledges a DOTS client's request
to remove the DOTS signal channel session configuration using 2.02 to remove the DOTS signal channel session configuration using 2.02
(Deleted) response code. (Deleted) response code.
5.6. Redirected Signaling 4.6. Redirected Signaling
Redirected Signaling is discussed in detail in Section 3.2.2 of Redirected DOTS signaling is discussed in detail in Section 3.2.2 of
[I-D.ietf-dots-architecture]. If the DOTS server wants to redirect [I-D.ietf-dots-architecture].
the DOTS client to an alternative DOTS server for a signaling session
then the response code 3.00 (alternate server) will be returned in If a DOTS server wants to redirect a DOTS client to an alternative
the response to the client. The DOTS server can return the error DOTS server for a signal session, then the response code 3.00
response code 3.00 in response to a PUT request from the DOTS client (alternate server) will be returned in the response to the client.
or convey the error response code 3.00 in a unidirectional The DOTS server can return the error response code 3.00 in response
notification response from the DOTS server. to a PUT request from the DOTS client or convey the error response
code 3.00 in a unidirectional notification response from the DOTS
server.
The DOTS server in the error response conveys the alternate DOTS The DOTS server in the error response conveys the alternate DOTS
server FQDN, and the alternate DOTS server IP addresses and time to server FQDN, and the alternate DOTS server IP addresses and time to
live values in the CBOR body. live values in the CBOR body.
{ {
"alt-server": "string", "alt-server": "string",
"alt-server-record": [ "alt-server-record": [
{ {
"addr": "string", "addr": "string",
"ttl" : integer, "ttl" : integer,
} }
] ]
} }
Figure 20: Error response body Figure 19: 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.
addr: IP address of an alternate DOTS server. addr: IP address of an alternate DOTS server.
ttl: Time to live (TTL) represented as an integer number of seconds. ttl: Time to live (TTL) represented as an integer number of seconds.
Figure 21 shows a 3.00 response example to convey the DOTS alternate Figure 20 shows a 3.00 response example to convey the DOTS alternate
server www.example-alt.com, its IP addresses 2001:db8:6401::1 and server www.example-alt.com, its IP addresses 2001:db8:6401::1 and
2001:db8:6401::2, and TTL values 3600 and 1800. 2001:db8:6401::2, and TTL values 3600 and 1800.
{ {
"alt-server": "www.example-alt.com", "alt-server": "www.example-alt.com",
"alt-server-record": [ "alt-server-record": [
{ {
"ttl" : 3600, "ttl" : 3600,
"addr": "2001:db8:6401::1" "addr": "2001:db8:6401::1"
}, },
{ {
"ttl" : 1800, "ttl" : 1800,
"addr": "2001:db8:6401::2" "addr": "2001:db8:6401::2"
} }
] ]
} }
Figure 21: Example of error response body Figure 20: 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 having failed, but SHOULD try the request with 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 subjected to DDOS attack, alternate DOTS server IP addresses conveyed
in the 3.00 response help the DOTS client to skip DNS lookup of the in the 3.00 response help the DOTS client to skip DNS lookup of the
alternate DOTS server and can try to establish UDP or TCP session alternate DOTS server and can try to establish UDP or TCP session
with the alternate DOTS server IP addresses. The DOTS client SHOULD with the alternate DOTS server IP addresses. The DOTS client SHOULD
implement DNS64 function to handle the scenario where IPv6-only DOTS implement DNS64 function to handle the scenario where IPv6-only DOTS
client communicates with IPv4-only alternate DOTS server. client communicates with IPv4-only alternate DOTS server.
5.7. Heartbeat Mechanism 4.7. Heartbeat Mechanism
To provide a metric of signal health and distinguish an 'idle' signal To provide a metric of signal health and distinguish an 'idle' signal
channel from a 'disconnected' or 'defunct' session, the DOTS agent channel from a 'disconnected' or 'defunct' session, the DOTS agent
sends a heartbeat over the signal channel to maintain its half of the sends a heartbeat over the signal channel to maintain its half of the
channel. The DOTS agent similarly expects a heartbeat from its peer channel. The DOTS agent similarly expects a heartbeat from its peer
DOTS agent, and may consider a session terminated in the extended DOTS agent, and may consider a session terminated in the extended
absence of a peer agent heartbeat. 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
skipping to change at page 42, line 40 skipping to change at page 37, line 40
[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 an Reset
message. message.
In DOTS over TCP, heartbeat messages can be exchanged between the In DOTS over TCP, heartbeat messages can 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.
6. Mapping parameters to CBOR 5. DOTS Signal Channel YANG Modules
All parameters in the payload in the DOTS signal channel MUST be This document defines YANG [RFC7950] modules for mitigation scope and
mapped to CBOR types as follows and are given an integer key to save DOTS signal channel session configuration data.
space. The recipient of the payload MAY reject the information if it
is not suitably mapped.
/--------------------+------------------------+--------------------------\ 5.1. Mitigation Request YANG Module Tree Structure
| Parameter name | CBOR key | CBOR major type of value |
+--------------------+------------------------+--------------------------+
| mitigation-scope | 1 | 5 (map) |
| scope | 2 | 5 (map) |
| mitigation-id | 3 | 0 (unsigned) |
| target-ip | 4 | 4 (array) |
| target-port-range | 5 | 4 |
| lower-port | 6 | 0 |
| upper-port | 7 | 0 |
| target-protocol | 8 | 4 |
| fqdn | 9 | 4 |
| uri | 10 | 4 |
| alias-name | 11 | 4 |
| lifetime | 12 | 0 |
| attack-status | 13 | 0 |
| signal-config | 14 | 5 |
| heartbeat-interval | 15 | 0 |
| max-retransmit | 16 | 0 |
| ack-timeout | 17 | 0 |
| ack-random-factor | 18 | 7 |
| MinValue | 19 | 0 |
| MaxValue | 20 | 0 |
| status | 21 | 0 |
| bytes-dropped | 22 | 0 |
| bps-dropped | 23 | 0 |
| pkts-dropped | 24 | 0 |
| pps-dropped | 25 | 0 |
| session-id | 26 | 0 |
| trigger-mitigation | 27 | 7 (simple types) |
| missing-hb-allowed | 28 | 0 |
| CurrentValue | 29 | 0 |
| mitigation-start | 30 | 7 (floating-point) |
| target-prefix | 31 | 4 (array) |
| client-identifier | 32 | 2 (byte string) |
| alt-server | 33 | 2 |
| alt-server-record | 34 | 4 |
| addr | 35 | 2 |
| ttl | 36 | 0 |
\--------------------+------------------------+--------------------------/
Figure 22: CBOR mappings used in DOTS signal channel message This document defines the YANG module "ietf-dots-signal"
(Section 5.2), which has the following tree structure:
7. (D)TLS Protocol Profile and Performance considerations module: ietf-dots-signal
+--rw mitigation-scope
+--rw client-identifier* binary
+--rw scope* [mitigation-id]
+--rw mitigation-id int32
+--rw target-ip* inet:ip-address
+--rw target-prefix* inet:ip-prefix
+--rw target-port-range* [lower-port upper-port]
| +--rw lower-port inet:port-number
| +--rw upper-port inet:port-number
+--rw target-protocol* uint8
+--rw fqdn* inet:domain-name
+--rw uri* inet:uri
+--rw alias-name* string
+--rw lifetime? int32
5.2. Mitigation Request YANG Module
<CODE BEGINS> file "ietf-dots-signal@2017-11-27.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";
}
organization "IETF DOTS Working Group";
contact
"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
"This module contains YANG definition for DOTS
signal sent by the DOTS client to the DOTS server.
Copyright (c) 2017 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
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).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2017-11-27 {
description
"Initial revision.";
reference
"RFC XXXX: A Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
container mitigation-scope {
description
"Specifies the scope of the mitigation request.";
leaf-list client-identifier {
type binary;
description
"The client identifier may be conveyed by
the DOTS gateway to propagate the DOTS client
identity from the gateway's client-side to the
gateway's server-side, and from the gateway's
server-side to the DOTS server.
It allows the final DOTS server to accept
mitigation requests with scopes which the DOTS
client is authorized to manage.";
}
list scope {
key mitigation-id;
description
"The scope of the request.";
leaf mitigation-id {
type int32;
description
"Mitigation request identifier.
This identifier must be unique for each mitigation
request bound to the DOTS client.";
}
leaf-list target-ip {
type inet:ip-address;
description
"IPv4 or IPv6 address identifying the target.";
}
leaf-list target-prefix {
type inet:ip-prefix;
description
"IPv4 or IPv6 prefix identifying the target.";
}
list target-port-range {
key "lower-port upper-port";
description
"Port range. When only lower-port is
present, it represents a single port.";
leaf lower-port {
type inet:port-number;
mandatory true;
description "Lower port number.";
}
leaf upper-port {
type inet:port-number;
must ". >= ../lower-port" {
error-message
"The upper port number must be greater than
or equal to lower port number.";
}
description "Upper port number.";
}
}
leaf-list target-protocol {
type uint8;
description
"Identifies the target protocol number.
The value '0' means 'all protocols'.
Values are taken from the IANA protocol registry:
https://www.iana.org/assignments/protocol-numbers/
protocol-numbers.xhtml
For example, 6 for a TCP or 17 for UDP.";
}
leaf-list fqdn {
type inet:domain-name;
description "FQDN";
}
leaf-list uri {
type inet:uri;
description "URI";
}
leaf-list alias-name {
type string;
description "alias name";
}
leaf lifetime {
type int32;
units "seconds";
default 3600;
description
"Indicates the lifetime of the mitigation request.";
}
}
}
}
<CODE ENDS>
5.3. Session Configuration YANG Module Tree Structure
This document defines the YANG module "ietf-dots-signal-config"
(Section 5.4), which has the following structure:
module: ietf-dots-signal-config
+--rw signal-config
+--rw session-id? int32
+--rw heartbeat-interval? int16
+--rw missing-hb-allowed? int16
+--rw max-retransmit? int16
+--rw ack-timeout? int16
+--rw ack-random-factor? decimal64
+--rw trigger-mitigation? boolean
5.4. Session Configuration YANG Module
<CODE BEGINS> file "ietf-dots-signal-config@2017-11-27.yang"
module ietf-dots-signal-config {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-signal-config";
prefix "config";
organization "IETF DOTS Working Group";
contact
"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
"This module contains YANG definition for DOTS
signal channel session configuration.
Copyright (c) 2017 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
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).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2017-11-27 {
description
"Initial revision.";
reference
"RFC XXXX: A Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel";
}
container signal-config {
description
"DOTS signal channel session configuration.";
leaf session-id {
type int32;
description
"An identifier for the DOTS signal channel
session configuration data.";
}
leaf heartbeat-interval {
type int16;
units "seconds";
default 30;
description
"DOTS agents regularly send heartbeats to each other
after mutual authentication in order to keep
the DOTS signal channel open.";
}
leaf missing-hb-allowed {
type int16;
default 5;
description
"Maximum number of missing heartbeats allowed.";
}
leaf max-retransmit {
type int16;
default 3;
description
"Maximum number of retransmissions of a
Confirmable message.";
}
leaf ack-timeout {
type int16;
units "seconds";
default 2;
description
"Initial retransmission timeout value.";
}
leaf ack-random-factor {
type decimal64 {
fraction-digits 2;
}
default 1.5;
description
"Random factor used to influence the timing of
retransmissions.";
}
leaf trigger-mitigation {
type boolean;
default true;
description
"If false, then mitigation is triggered
only when the DOTS server channel session is lost";
}
}
}
<CODE ENDS>
6. Mapping Parameters to CBOR
All parameters in the payload in the DOTS signal channel MUST be
mapped to CBOR types as shown in Table 4 and are given an integer key
to save space. The recipient of the payload MAY reject the
information if it is not suitably mapped.
/--------------------+---------------------+--------------------------\
| Parameter name | CBOR key | CBOR major type of value |
+--------------------+---------------------+--------------------------+
| mitigation-scope | 1 | 5 (map) |
| scope | 2 | 5 (map) |
| mitigation-id | 3 | 0 (unsigned) |
| target-ip | 4 | 4 (array) |
| target-port-range | 5 | 4 |
| lower-port | 6 | 0 |
| upper-port | 7 | 0 |
| target-protocol | 8 | 4 |
| fqdn | 9 | 4 |
| uri | 10 | 4 |
| alias-name | 11 | 4 |
| lifetime | 12 | 0 |
| attack-status | 13 | 0 |
| signal-config | 14 | 5 |
| heartbeat-interval | 15 | 0 |
| max-retransmit | 16 | 0 |
| ack-timeout | 17 | 0 |
| ack-random-factor | 18 | 7 |
| MinValue | 19 | 0 |
| MaxValue | 20 | 0 |
| status | 21 | 0 |
| bytes-dropped | 22 | 0 |
| bps-dropped | 23 | 0 |
| pkts-dropped | 24 | 0 |
| pps-dropped | 25 | 0 |
| session-id | 26 | 0 |
| trigger-mitigation | 27 | 7 (simple types) |
| missing-hb-allowed | 28 | 0 |
| CurrentValue | 29 | 0 |
| mitigation-start | 30 | 7 (floating-point) |
| target-prefix | 31 | 4 (array) |
| client-identifier | 32 | 2 (byte string) |
| alt-server | 33 | 2 |
| alt-server-record | 34 | 4 |
| addr | 35 | 2 |
| ttl | 36 | 0 |
\--------------------+---------------------+--------------------------/
Table 4: CBOR mappings used in DOTS signal channel message
7. (D)TLS Protocol Profile and Performance Considerations
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 machine-in-the-middle and
protocol downgrade. These are general attacks on (D)TLS and not protocol downgrade. These are general attacks on (D)TLS and not
specific to DOTS over (D)TLS; please refer to the (D)TLS RFCs for specific to DOTS over (D)TLS; please refer to the (D)TLS RFCs for
discussion of these security issues. DOTS agents MUST adhere to the discussion of these security issues. DOTS agents MUST adhere to the
(D)TLS implementation recommendations and security considerations of (D)TLS implementation recommendations and security considerations of
[RFC7525] except with respect to (D)TLS version. Since encryption of [RFC7525] except with respect to (D)TLS version. Since encryption of
skipping to change at page 44, line 23 skipping to change at page 46, line 27
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, DOTS client MUST verify the entire certification path
per [RFC5280]. The DOTS client additionaly uses [RFC6125] validation per [RFC5280]. The DOTS client additionaly uses [RFC6125] validation
techniques to compare the domain name to the certificate provided. techniques to compare the domain name to the certificate provided.
A key challenge to deploying DOTS is provisioning DOTS clients, A key challenge to deploying DOTS is provisioning DOTS clients,
including the distribution of keying material to DOTS clients to make including the distribution of keying material to DOTS clients to make
possible the required mutual authentication of DOTS agents. This possible the required mutual authentication of DOTS agents. EST
specification relies on EST to overcome this. EST defines a method defines a method of certificate enrollment by which domains operating
of certificate enrollment by which domains operating DOTS servers may DOTS servers may provision DOTS clients with all necessary
provision DOTS clients with all necessary cryptographic keying cryptographic keying material, including a private key and
material, including a private key and certificate with which to certificate with which to authenticate itself. One deployment option
authenticate itself. This document does not specify which EST is DOTS clients to behave as EST clients for certificate enrollment
mechanism the DOTS client uses to achieve initial enrollment. from an EST server provisioned by the mitigation provider. This
document does not specify which EST mechanism the DOTS client uses to
achieve 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.
skipping to change at page 45, line 12 skipping to change at page 47, line 20
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.
7.1. MTU and Fragmentation Issues 7.2. MTU and Fragmentation
To avoid DOTS signal message fragmentation and the consequently To avoid DOTS signal message fragmentation and the consequently
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-ip' parameter could be
split into multiple lists and each list conveyed in a new PUT 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 absolutely ensure that there is no IP
fragmentation. If IPv4 support on unusual networks is a fragmentation. If IPv4 support on unusual networks is a
consideration and path MTU is unknown, implementations may want to consideration and path MTU is unknown, implementations may want to
limit themselves to more conservative IPv4 datagram sizes such as 576 limit themselves to more conservative IPv4 datagram sizes such as 576
bytes, as per [RFC0791] IP packets up to 576 bytes should never need bytes, as per [RFC0791] IP packets up to 576 bytes should never need
to be fragmented, thus sending a maximum of 500 bytes of DOTS signal to be fragmented, thus sending a maximum of 500 bytes of DOTS signal
over a UDP datagram will generally avoid IP fragmentation. over a UDP datagram will generally avoid IP fragmentation.
8. (D)TLS 1.3 considerations 8. (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.rescorla-tls-dtls13] is based on the TLS 1.3 protocol and [I-D.rescorla-tls-dtls13] is based on the TLS 1.3 protocol and
provides equivalent security guarantees. (D)TLS 1.3 provides two provides equivalent security guarantees. (D)TLS 1.3 provides two
basic handshake modes of interest to DOTS signal channel: basic handshake modes of interest to DOTS signal channel:
o Absent packet loss, a full handshake in which the DOTS client is o Absent packet loss, a full handshake in which the DOTS client is
able to send the DOTS signal message after one round trip and the able to send the DOTS signal message after one round trip and the
DOTS server immediately after receiving the first DOTS signal DOTS server immediately after receiving the first DOTS signal
skipping to change at page 46, line 16 skipping to change at page 48, line 29
send DOTS signal message on its first flight, thus reducing send DOTS signal message on its first flight, thus reducing
handshake latency. 0-RTT only works if the DOTS client has handshake latency. 0-RTT only works if the DOTS client has
previously communicated with that DOTS server, which is very previously communicated with that DOTS server, which is very
likely with the DOTS signal channel. The DOTS client SHOULD likely with the DOTS signal channel. The DOTS client SHOULD
establish a (D)TLS session with the DOTS server during peacetime establish a (D)TLS session with the DOTS server during peacetime
and share a PSK. During DDOS attack, the DOTS client can use the and share a PSK. During DDOS attack, the DOTS client can use the
(D)TLS session to convey the DOTS signal message and if there is (D)TLS session to convey the DOTS signal message and if there is
no response from the server after multiple re-tries then the DOTS no response from the server after multiple re-tries then the DOTS
client can resume the (D)TLS session in 0-RTT mode using PSK. A client can resume the (D)TLS session in 0-RTT mode using PSK. A
simplified TLS 1.3 handshake with 0-RTT DOTS signal message simplified TLS 1.3 handshake with 0-RTT DOTS signal message
exchange is shown in Figure 23. exchange is shown in Figure 21.
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}
{Certificate} {Certificate}
{CertificateVerify} {CertificateVerify}
{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 21: TLS 1.3 handshake with 0-RTT
9. Mutual Authentication of DOTS Agents & Authorization of DOTS Clients 9. Mutual Authentication of DOTS Agents & Authorization of DOTS Clients
(D)TLS based on client certificate can be used for mutual (D)TLS based on 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 gateway 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. DOTS gateway and DOTS server MUST perform mutual
authentication; DOTS server only allows DOTS signals from authorized authentication; DOTS server only allows DOTS signals from authorized
DOTS gateway, creating a two-link chain of transitive authentication DOTS gateway, creating a two-link chain of transitive authentication
between the DOTS client and the DOTS server. 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) | | | |
| +---------------+ | | | example.net domain | +---------------+ | | |
| V V | | V V | example.net domain
| +-------------+ | +---------------+ | +-----+----+--+ | +---------------+
| +--------------+ | | | | | | +--------------+ | | | | |
| | Guest +<-----x----->+ +<---------------->+ DOTS | | | Guest +<-----x----->+ DOTS +<------>+ DOTS |
| | (DOTS client)| | DOTS | | | Server | | | (DOTS client)| | Gateway | | | Server |
| +--------------+ | Gateway | | | | | +--------------+ | | | | |
| +----+--------+ | +---------------+ | +----+--------+ | +---------------+
| ^ | | ^ |
| | | | | |
| +----------------+ | | | +----------------+ | |
| | DDOS detector | | | | | DDOS detector | | |
| | (DOTS client) +<--------------+ | | | (DOTS client) +<---------------+ |
| +----------------+ | | +----------------+ |
| | +-----------------------------------------------+
+-------------------------------------------------+
Figure 24: Example of Authentication and Authorization of DOTS Agents Figure 22: 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 22, 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 detector to request DDOS mitigation, but does not permit the
user of type 'guest' to request DDOS mitigation. user of type 'guest' to request DDOS mitigation.
Also, DOTS gateway and DOTS server located in different domains MUST Also, DOTS gateway and DOTS server 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 22, 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.
10. IANA Considerations 10. IANA Considerations
This specification registers a default port, new URI suffix in the This specification registers a default port, new URI suffix in the
Well-Known URIs registry, new CoAP response code, new parameters for Well-Known URIs registry, new CoAP response code, new parameters for
DOTS signal channel and establishes registries for mappings to CBOR. DOTS signal channel and establishes registries for mappings to CBOR.
10.1. DOTS Signal Channel UDP and TCP Port Number 10.1. DOTS Signal Channel UDP and TCP Port Number
skipping to change at page 48, line 34 skipping to change at page 50, line 42
Specification document(s): This RFC Specification document(s): This RFC
Related information: None Related information: None
10.3. CoAP Response Code 10.3. CoAP Response Code
The following entry is added to the "CoAP Response Codes" sub- The following entry is added to the "CoAP Response Codes" sub-
registry: registry:
+------+------------------------------+-----------+ +------+-------------------+-----------+
| Code | Description | Reference | | Code | Description | Reference |
+------+------------------------------+-----------+ +------+-------------------+-----------+
| 3.00 | Alternate server | [RFCXXXX] | | 3.00 | Alternate server | [RFCXXXX] |
+------+------------------------------+-----------+ +------+-------------------+-----------+
Figure 25: CoAP Response Code
[Note to RFC Editor: Please replace XXXX with the RFC number of this Table 4: CoAP Response Code
specification.]
10.4. DOTS signal channel CBOR Mappings Registry 10.4. DOTS Signal Channel CBOR Mappings Registry
A new registry will be requested from IANA, entitled "DOTS signal A new registry will be requested from IANA, entitled "DOTS signal
channel CBOR Mappings Registry". The registry is to be created as channel CBOR Mappings Registry". The registry is to be created as
Expert Review Required. Expert Review Required.
10.4.1. Registration Template 10.4.1. Registration Template
Parameter name: Parameter name:
Parameter names (e.g., "target_ip") in the DOTS signal channel. Parameter names (e.g., "target_ip") in the DOTS signal channel.
skipping to change at page 54, line 6 skipping to change at page 56, line 12
o CBOR Major Type: 2 o CBOR Major Type: 2
o Change Controller: IESG o Change Controller: IESG
o Specification Document(s): this document o Specification Document(s): this document
o Parameter Name:ttl o Parameter Name:ttl
o CBOR Key Value: 36 o CBOR Key Value: 36
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
10.5. YANG Modules
This document requests IANA to register the following URIs in the
"IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-dots-signal
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
URI: urn:ietf:params:xml:ns:yang:ietf-dots-signal-config
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
This document requests IANA to register the following YANG modules in
the "YANG Module Names" registry [RFC7950].
name: ietf-signal
namespace: urn:ietf:params:xml:ns:yang:ietf-dots-signal
prefix: signal
reference: RFC XXXX
name: ietf-dots-signal-config
namespace: urn:ietf:params:xml:ns:yang:ietf-dots-signal-config
prefix: config
reference: RFC XXXX
11. Implementation Status 11. 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 of this
Internet-Draft, and is based on a proposal described in [RFC7942]. Internet-Draft, and is based on 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 processes in progressing drafts to
skipping to change at page 56, line 39 skipping to change at page 59, line 21
Silverajan, B., and B. Raymor, "CoAP (Constrained Silverajan, B., and B. Raymor, "CoAP (Constrained
Application Protocol) over TCP, TLS, and WebSockets", Application Protocol) over TCP, TLS, and WebSockets",
draft-ietf-core-coap-tcp-tls-10 (work in progress), draft-ietf-core-coap-tcp-tls-10 (work in progress),
October 2017. October 2017.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key [RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)", Ciphersuites for Transport Layer Security (TLS)",
RFC 4279, DOI 10.17487/RFC4279, December 2005, RFC 4279, DOI 10.17487/RFC4279, December 2005,
<https://www.rfc-editor.org/info/rfc4279>. <https://www.rfc-editor.org/info/rfc4279>.
[RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, (TLS) Protocol Version 1.2", RFC 5246,
DOI 10.17487/RFC5246, August 2008, DOI 10.17487/RFC5246, August 2008,
<https://www.rfc-editor.org/info/rfc5246>. <https://www.rfc-editor.org/info/rfc5246>.
skipping to change at page 58, line 10 skipping to change at page 60, line 43
"Recommendations for Secure Use of Transport Layer "Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May (DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>. 2015, <https://www.rfc-editor.org/info/rfc7525>.
[RFC7641] Hartke, K., "Observing Resources in the Constrained [RFC7641] Hartke, K., "Observing Resources in the Constrained
Application Protocol (CoAP)", RFC 7641, Application Protocol (CoAP)", RFC 7641,
DOI 10.17487/RFC7641, September 2015, DOI 10.17487/RFC7641, September 2015,
<https://www.rfc-editor.org/info/rfc7641>. <https://www.rfc-editor.org/info/rfc7641>.
[RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
RFC 7950, DOI 10.17487/RFC7950, August 2016,
<https://www.rfc-editor.org/info/rfc7950>.
15.2. Informative References 15.2. 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-01 (work in
progress), July 2017. progress), July 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",
skipping to change at page 58, line 34 skipping to change at page 61, line 22
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-07 (work in progress), November ietf-dots-data-channel-08 (work in progress), November
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-07 (work in
progress), October 2017. progress), October 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]
Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
ietf-netmod-yang-tree-diagrams-02 (work in progress),
October 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-tls13-21 (work in progress),
July 2017. July 2017.
[I-D.rescorla-tls-dtls13] [I-D.rescorla-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-rescorla-tls-dtls13-01 (work in progress), 1.3", draft-rescorla-tls-dtls13-01 (work in progress),
March 2017. March 2017.
skipping to change at page 60, line 5 skipping to change at page 62, line 46
[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>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<https://www.rfc-editor.org/info/rfc6020>.
[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>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed., [RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
skipping to change at page 60, line 32 skipping to change at page 63, line 23
<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
Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014, Fast Open", RFC 7413, DOI 10.17487/RFC7413, December 2014,
<https://www.rfc-editor.org/info/rfc7413>. <https://www.rfc-editor.org/info/rfc7413>.
[RFC7469] Evans, C., Palmer, C., and R. Sleevi, "Public Key Pinning
Extension for HTTP", RFC 7469, DOI 10.17487/RFC7469, April
2015, <https://www.rfc-editor.org/info/rfc7469>.
[RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the [RFC7589] Badra, M., Luchuk, A., and J. Schoenwaelder, "Using the
NETCONF Protocol over Transport Layer Security (TLS) with NETCONF Protocol over Transport Layer Security (TLS) with
Mutual X.509 Authentication", RFC 7589, Mutual X.509 Authentication", RFC 7589,
DOI 10.17487/RFC7589, June 2015, DOI 10.17487/RFC7589, June 2015,
<https://www.rfc-editor.org/info/rfc7589>. <https://www.rfc-editor.org/info/rfc7589>.
[RFC7918] Langley, A., Modadugu, N., and B. Moeller, "Transport [RFC7918] Langley, A., Modadugu, N., and B. Moeller, "Transport
Layer Security (TLS) False Start", RFC 7918, Layer Security (TLS) False Start", RFC 7918,
DOI 10.17487/RFC7918, August 2016, DOI 10.17487/RFC7918, August 2016,
<https://www.rfc-editor.org/info/rfc7918>. <https://www.rfc-editor.org/info/rfc7918>.
 End of changes. 131 change blocks. 
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