DOTS M. Boucadair
Internet-Draft Orange
Intended status: Standards Track T. Reddy
Expires: February 6, 2020 McAfee
August 5, 2019
Distributed-Denial-of-Service Open Threat Signaling (DOTS) Agent
Discovery
draft-ietf-dots-server-discovery-05
Abstract
It may not be possible for a network to determine the cause for an
attack, but instead just realize that some resources seem to be under
attack. To fill that gap, Distributed-Denial-of-Service Open Threat
Signaling (DOTS) allows a network to inform a DOTS server that it is
under a potential attack so that appropriate mitigation actions are
undertaken.
This document specifies mechanisms to configure DOTS clients with
DOTS servers. The discovery procedure also covers the DOTS Signal
Channel Call Home.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 6, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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(https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Why Multiple Discovery Mechanisms? . . . . . . . . . . . . . 5
4. Unified DOTS Discovery Procedure . . . . . . . . . . . . . . 6
5. DHCP Options for DOTS Agent Discovery . . . . . . . . . . . . 8
5.1. DHCPv6 DOTS Options . . . . . . . . . . . . . . . . . . . 8
5.1.1. Format of DOTS Reference Identifier Option . . . . . 8
5.1.2. Format of DOTS Address Option . . . . . . . . . . . . 9
5.1.3. DHCPv6 Client Behavior . . . . . . . . . . . . . . . 10
5.2. DHCPv4 DOTS Options . . . . . . . . . . . . . . . . . . . 11
5.2.1. Format of DOTS Reference Identifier Option . . . . . 11
5.2.2. Format of DOTS Address Option . . . . . . . . . . . . 12
5.2.3. DHCPv4 Client Behavior . . . . . . . . . . . . . . . 12
6. Discovery using Service Resolution . . . . . . . . . . . . . 13
7. DNS Service Discovery . . . . . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 16
8.1. DHCP . . . . . . . . . . . . . . . . . . . . . . . . . . 16
8.2. Service Resolution . . . . . . . . . . . . . . . . . . . 16
8.3. DNS Service Discovery . . . . . . . . . . . . . . . . . . 16
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 17
9.1. DHCPv6 Option . . . . . . . . . . . . . . . . . . . . . . 17
9.2. DHCPv4 Option . . . . . . . . . . . . . . . . . . . . . . 17
9.3. Application Service & Application Protocol Tags . . . . . 17
9.3.1. DOTS Application Service Tag Registration . . . . . . 17
9.3.2. DOTS Call Home Application Service Tag Registration . 18
9.3.3. signal.udp Application Protocol Tag Registration . . 18
9.3.4. signal.tcp Application Protocol Tag Registration . . 18
9.3.5. data.tcp Application Protocol Tag Registration . . . 18
10. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 18
11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
12.1. Normative References . . . . . . . . . . . . . . . . . . 19
12.2. Informative References . . . . . . . . . . . . . . . . . 20
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 21
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1. Introduction
DDoS Open Threat Signaling (DOTS) [I-D.ietf-dots-architecture]
specifies an architecture, in which a DOTS client can inform a DOTS
server that the network is under a potential attack and that
appropriate mitigation actions are required. Indeed, because the
lack of a common method to coordinate a real-time response among
involved actors and network domains inhibits the effectiveness of
DDoS attack mitigation, DOTS signal channel protocol
[I-D.ietf-dots-signal-channel] is meant to carry requests for DDoS
attack mitigation, thereby reducing the impact of an attack and
leading to more efficient defensive actions in various deployment
scenarios such as those discussed in [I-D.ietf-dots-use-cases].
Moreover, DOTS clients can instruct a DOTS server to install
filtering rules by means of DOTS data channel
[I-D.ietf-dots-data-channel].
The basic high-level DOTS architecture is illustrated in Figure 1:
+-----------+ +-------------+
| Mitigator | ~~~~~~~~~~ | DOTS Server |
+-----------+ +------+------+
|
|
|
+---------------+ +------+------+
| Attack Target | ~~~~~~ | DOTS Client |
+---------------+ +-------------+
Figure 1: Basic DOTS Architecture
[I-D.ietf-dots-architecture] specifies that the DOTS client may be
provided with a list of DOTS servers; each associated with one or
more IP addresses. These addresses may or may not be of the same
address family. The DOTS client establishes one or more DOTS
sessions by connecting to the provided DOTS server addresses.
This document specifies methods for DOTS clients to discover their
DOTS server(s). The rationale for specifying multiple discovery
mechanisms is discussed in Section 3.
The discovery methods can also be used by a DOTS server to locate a
DOTS client in the context of DOTS Signal Channel Call Home
[I-D.ietf-dots-signal-call-home]. The basic high-level DOTS Call
Home architecture is illustrated in Figure 2:
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+---------------+ +-------------+
| Alert/DMS/ | ~~~~~~ | Call Home |
| Peer DMS/... | | DOTS client |
+---------------+ +------+------+
|
|
|
+---------------+ +------+------+
| Attack | ~~~~~~ | Call Home |
| Source(s) | | DOTS server |
+---------------+ +-------------+
Figure 2: Basic DOTS Signal Channel Call Home Functional Architecture
A DOTS agent may be used to establish base DOTS channels, DOTS Call
Home, or both. This specification accommodates all these deployment
cases.
Considerations for the selection of DOTS server(s) by multi-homed
DOTS clients is out of scope; the reader should refer to
[I-D.ietf-dots-multihoming] for more details.
This document assumes that security credentials to authenticate DOTS
server(s) are provisioned to a DOTS client using a variety of means
such as (but not limited to) those discussed in
[I-D.ietf-netconf-zerotouch] or
[I-D.ietf-anima-bootstrapping-keyinfra]. DOTS clients use those
credentials for authentication purposes following the rules
documented in [I-D.ietf-dots-signal-channel].
2. 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 BCP
14 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
The reader should be familiar with the terms defined in
[I-D.ietf-dots-architecture], [RFC3958], and
[I-D.ietf-dots-signal-call-home].
DHCP refers to both DHCPv4 [RFC2131] and DHCPv6 [RFC8415].
"Peer DOTS agent" refers to the peer DOTS server (base DOTS
operation) or to a peer Call Home DOTS client (for DOTS Signal
Channel Call Home).
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3. Why Multiple Discovery Mechanisms?
It is tempting to specify one single discovery mechanism for DOTS.
Nevertheless, the analysis of the various use cases sketched in
[I-D.ietf-dots-use-cases] reveals that it is unlikely that one single
discovery method can be suitable for all the sample deployments.
Concretely:
o Many use cases discussed in [I-D.ietf-dots-use-cases] do involve a
CPE device. Multiple CPEs, connected to distinct network
providers may even be considered. It is intuitive to leverage on
existing mechanisms such as discovery using service resolution or
DHCP to provision the CPE acting as a DOTS client with the DOTS
server(s).
o Resolving a DOTS server domain name offered by an upstream transit
provider provisioned to a DOTS client into IP address(es) require
the use of the appropriate DNS resolvers; otherwise, resolving
those names will fail. The use of protocols such as DHCP does
allow to associate provisioned DOTS server domain names with a
list of DNS servers to be used for name resolution. Furthermore,
DHCP allows to directly provision IP addresses avoiding therefore
the need for extra lookup delays.
o Some of the use cases may allow DOTS clients to have direct
communications with upstream DOTS servers; that is no DOTS gateway
is involved. Leveraging on existing features that do not require
specific feature on the node embedding the DOTS client may ease
DOTS deployment. Typically, the use of Straightforward-Naming
Authority Pointer (S-NAPTR) lookups [RFC3958] allows the DOTS
server administrators to provision the preferred DOTS transport
protocol between the DOTS client and the DOTS server and allows
the DOTS client to discover this preference.
o The upstream network provider is not the DDoS mitigation provider
for some of these use cases. It is safe to assume that for such
deployments, the DOTS server(s) domain name is provided during the
service subscription (i.e., manual/local configuration).
o Multiple DOTS clients may be enabled within a network (e.g.,
enterprise network). Dynamic means to discover DOTS servers in a
deterministic manner are interesting from an operational
standpoint.
o Some of the use cases may involve a DOTS gateway that is
responsible for selecting the appropriate DOTS server(s) to relay
requests received from DOTS clients.
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Consequently, this document describes a unified discovery logic
(Section 4) which involves the following mechanisms:
o Dynamic discovery using DHCP (Section 5).
o A resolution mechanism based on straightforward Naming Authority
Pointer (S-NAPTR) resource records in the Domain Name System (DNS)
(Section 6).
o DNS Service Discovery (Section 7).
4. Unified DOTS Discovery Procedure
A key point in the deployment of DOTS is the ability of network
operators to be able to configure DOTS clients with the correct DOTS
server(s) information consistently. To accomplish this, operators
will need a consistent set of ways in which DOTS clients can discover
this information, and a consistent priority among these options. If
some devices prefer manual configuration over dynamic discovery,
while others prefer dynamic discovery over manual configuration, the
result will be a process of "whack-a-mole", where the operator must
find devices that are using the wrong DOTS server(s), determine how
to ensure the devices are configured properly, and then reconfigure
the device through the preferred method.
All DOTS clients MUST support at least one of the three mechanisms
below to determine a DOTS server list. All DOTS clients SHOULD
implement all three, or as many as are practical for any specific
device (e.g., a CPE will support the first two mechanisms, a host
within a LAN will support the last two mechanisms, or an application
server will support a local configuration. More samples are
discussed in Section 3), of these ways to discover DOTS servers, in
order to facilitate the deployment of DOTS in large scale
environments:
1. Explicit configuration:
* Local/Manual configuration: A DOTS client, will learn the DOTS
server(s) by means of local or manual DOTS configuration
(i.e., DOTS servers configured at the system level).
Configuration discovered from a DOTS client application is
considered as local configuration.
An implementation may give the user an opportunity (e.g., by
means of configuration file options or menu items) to specify
DOTS server(s) for each address family. These may be
specified either as IP addresses or the DNS name of a DOTS
server. When only DOTS server's IP addresses are configured,
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a reference identifier must also be configured for
authentication purposes.
* Automatic configuration (e.g., DHCP, an automation system):
The DOTS client attempts to discover DOTS server(s) names and/
or addresses from DHCP, as described in Section 5.
2. Service Resolution : The DOTS client attempts to discover DOTS
server name(s) using service resolution, as specified in
Section 6.
3. DNS SD: DNS Service Discovery. The DOTS client attempts to
discover DOTS server name(s) using DNS service discovery, as
specified in Section 7.
Some of these mechanisms imply the use of DNS to resolve the IP
address(es) of the DOTS server, while others imply an IP address of
the relevant DOTS server is obtained directly. Implementation
options may vary on a per device basis, as some devices may not have
DNS capabilities and/or proper configuration.
DOTS clients will prefer information received from the discovery
methods in the order listed.
On hosts with more than one interface or address family (IPv4/v6),
the DOTS server discovery procedure has to be performed for each
combination of interface and address family. A DOTS client may
choose to perform the discovery procedure only for a desired
interface/address combination if the client does not wish to discover
a DOTS server for all combinations of interface and address family.
This procedure is also followed by a Call Home DOTS server to
discover its Call Home DOTS client in the context of
[I-D.ietf-dots-signal-call-home].
The discovery method is reiterated by a DOTS agent upon the following
events:
o Expiry of a lease associated with a discovered DOTS agent.
o Expiry of a peer DOTS agent's certificate currently in use.
o Attachment to a new network.
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5. DHCP Options for DOTS Agent Discovery
As reported in Section 1.7.2 of [RFC6125]:
"few certification authorities issue server certificates based on
IP addresses, but preliminary evidence indicates that such
certificates are a very small percentage (less than 1%) of issued
certificates".
In order to allow for PKIX-based authentication between a DOTS client
and server while accommodating for the current best practices for
issuing certificates, this document allows for configuring names to
DOTS clients. These names can be used for two purposes: to retrieve
the list of IP addresses of a DOTS server or to be presented as a
reference identifier for authentication purposes.
Defining the option to include a list of IP addresses would avoid a
dependency on an underlying name resolution, but that design requires
to also supply a name for PKIX-based authentication purposes.
The design assumes that the same peer DOTS agent is used for
establishing both signal and data channels. For more customized
configurations (e.g., transport-specific configuration, distinct DOTS
servers for the signal and the data channels), an operator can supply
only a DOTS reference identifier that will be then passed to the
procedure described in Section 6.
The design allows to terminate the base DOTS channels and DOTS Call
Home on the same or distinct peer DOTS agents. If distinct peer DOTS
agents are deployed, the DHCP option can return, for example, a list
of IP addresses to a requesting DOTS agent. This list includes the
IP address to be used for the base DOTS channels and the IP address
for the DOTS Call Home. The DOTS client (or the Call Home DOTS
server) will then use the address selection specified in Section 4.3
of [I-D.ietf-dots-signal-channel] to identify the IP address of the
peer DOTS server (or Call Home Client).
5.1. DHCPv6 DOTS Options
5.1.1. Format of DOTS Reference Identifier Option
The DHCPv6 DOTS Reference Identifier option is used to configure a
name of the DOTS server (or the name of the Call Home DOTS client).
The format of this option is shown in Figure 3.
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_V6_DOTS_RI | Option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| dots-agent-name (FQDN) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: DHCPv6 DOTS Reference Identifier Option
The fields of the option shown in Figure 3 are as follows:
o Option-code: OPTION_V6_DOTS_RI (TBA1, see Section 9.1)
o Option-length: Length of the dots-agent-name field in octets.
o dots-agent-name: A fully qualified domain name of the peer DOTS
agent. This field is formatted as specified in Section 10 of
[RFC8415].
An example of the dots-agent-name encoding is shown in Figure 4.
This example conveys the FQDN "dots.example.com.".
+------+------+------+------+------+------+------+------+------+
| 0x04 | d | o | t | s | 0x07 | e | x | a |
+------+------+------+------+------+------+------+------+------+
| m | p | l | e | 0x03 | c | o | m | 0x00 |
+------+------+------+------+------+------+------+------+------+
Figure 4: An example of the dots-agent-name Encoding
5.1.2. Format of DOTS Address Option
The DHCPv6 DOTS Address option can be used to configure a list of
IPv6 addresses of a DOTS server (or a Call Home DOTS client). The
format of this option is shown in Figure 5. As a reminder, this
format follows the guidelines for creating new DHCPv6 options
(Section 5.1 of [RFC7227]).
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| OPTION_V6_DOTS_ADDRESS | Option-length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| DOTS ipv6-address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| DOTS ipv6-address |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: DHCPv6 DOTS Address Option
The fields of the option shown in Figure 5 are as follows:
o Option-code: OPTION_V6_DOTS_ADDRESS (TBA2, see Section 9.1)
o Option-length: Length of the 'DOTS ipv6-address(es)' field in
octets. MUST be a multiple of 16.
o DOTS ipv6-address: Includes one or more IPv6 addresses [RFC4291]
of the peer DOTS agent to be used by a DOTS agent for establishing
a DOTS session.
Note, IPv4-mapped IPv6 addresses (Section 2.5.5.2 of [RFC4291])
are allowed to be included in this option.
5.1.3. DHCPv6 Client Behavior
DHCP clients MAY request options OPTION_V6_DOTS_RI and
OPTION_V6_DOTS_ADDRESS, as defined in [RFC8415], Sections 18.2.1,
18.2.2, 18.2.4, 18.2.5, 18.2.6, and 21.7. As a convenience to the
reader, it is mentioned here that the DHCP client includes the
requested option codes in the Option Request Option.
If the DHCP client receives more than one instance of
OPTION_V6_DOTS_RI (or OPTION_V6_DOTS_ADDRESS) option, it MUST use
only the first instance of that option.
If the DHCP client receives both OPTION_V6_DOTS_RI and
OPTION_V6_DOTS_ADDRESS, the content of OPTION_V6_DOTS_RI is used as
reference identifier for authentication purposes (e.g., PKIX
[RFC6125]), while the addresses included in OPTION_V6_DOTS_ADDRESS
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are used to reach the peer DOTS agent. In other words, the name
conveyed in OPTION_V6_DOTS_RI MUST NOT be passed to underlying
resolution library in the presence of OPTION_V6_DOTS_ADDRESS in a
response.
If the DHCP client receives OPTION_V6_DOTS_RI only, but
OPTION_V6_DOTS_RI option contains more than one name, as
distinguished by the presence of multiple root labels, the DHCP
client MUST use only the first name. Once the name is validated
(Section 8 of [RFC8415]), the name is passed to a name resolution
library. Moreover, that name is also used as a reference identifier
for authentication purposes.
If the DHCP client receives OPTION_V6_DOTS_ADDRESS only, the
address(es) included in OPTION_V6_DOTS_ADDRESS are used to reach the
peer DOTS agent. In addition, these addresses can be used as
identifiers for authentication.
The DHCP client MUST silently discard multicast and host loopback
addresses [RFC6890] conveyed in OPTION_V6_DOTS_ADDRESS.
5.2. DHCPv4 DOTS Options
5.2.1. Format of DOTS Reference Identifier Option
The DHCPv4 DOTS Reference Identifier option is used to configure a
name of the peer DOTS agent. The format of this option is
illustrated in Figure 6.
Code Length Peer DOTS agent name
+-----+-----+-----+-----+-----+-----+-----+--
|TBA3 | n | s1 | s2 | s3 | s4 | s5 | ...
+-----+-----+-----+-----+-----+-----+-----+--
The values s1, s2, s3, etc. represent the domain name labels in the
domain name encoding.
Figure 6: DHCPv4 DOTS Reference Identifier Option
The fields of the option shown in Figure 6 are as follows:
o Code: OPTION_V4_DOTS_RI (TBA3, see Section 9.2).
o Length: Includes the length of the "Peer DOTS agent name" field in
octets; the maximum length is 255 octets.
o Peer DOTS agent name: The domain name of the peer DOTS agent.
This field is formatted as specified in Section 10 of [RFC8415].
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5.2.2. Format of DOTS Address Option
The DHCPv4 DOTS Address option can be used to configure a list of
IPv4 addresses of a peer DOTS agent. The format of this option is
illustrated in Figure 7.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code=TBA4 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
+ DOTS IPv4 Address |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---
| | |
+ DOTS IPv4 Address | |
| | optional
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
. ... . |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ ---
Figure 7: DHCPv4 DOTS Address Option
The fields of the option shown in Figure 7 are as follows:
o Code: OPTION_V4_DOTS_ADDRESS (TBA4, see Section 9.2).
o Length: is set to 4*N, where N is the number of IPv4 addresses
included in the option.
o DOTS IPv4 Address(es): Contains one or more IPv4 addresses of the
peer DOTS agent to be used by a DOTS agent.
OPTION_V4_DOTS_ADDRESS is a concatenation-requiring option. As such,
the mechanism specified in [RFC3396] MUST be used if
OPTION_V4_DOTS_ADDRESS exceeds the maximum DHCPv4 option size of 255
octets.
5.2.3. DHCPv4 Client Behavior
To discover a peer DOTS agent, the DHCPv4 client MUST include both
OPTION_V4_DOTS_RI and OPTION_V4_DOTS_ADDRESS in a Parameter Request
List Option [RFC2132].
If the DHCP client receives more than one instance of
OPTION_V4_DOTS_RI (or OPTION_V4_DOTS_ADDRESS) option, it MUST use
only the first instance of that option.
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If the DHCP client receives both OPTION_V4_DOTS_RI and
OPTION_V4_DOTS_ADDRESS, the content of OPTION_V6_DOTS_RI is used as
reference identifier for authentication purposes, while the addresses
included in OPTION_V4_DOTS_ADDRESS are used to reach the peer DOTS
agent. In other words, the name conveyed in OPTION_V4_DOTS_RI MUST
NOT be passed to underlying resolution library in the presence of
OPTION_V4_DOTS_ADDRESS in a response.
If the DHCP client receives OPTION_V4_DOTS_RI only, but
OPTION_V4_DOTS_RI option contains more than one name, as
distinguished by the presence of multiple root labels, the DHCP
client MUST use only the first name. Once the name is validated
(Section 10 of [RFC8415]), the name is passed to a name resolution
library. Moreover, that name is also used as a reference identifier
for authentication purposes.
If the DHCP client receives OPTION_V4_DOTS_ADDRESS only, the
address(es) included in OPTION_V4_DOTS_ADDRESS are used to reach the
peer DOTS server. In addition, these addresses can be used as
identifiers for authentication.
The DHCP client MUST silently discard multicast and host loopback
addresses conveyed in OPTION_V4_DOTS_ADDRESS.
6. Discovery using Service Resolution
This mechanism is performed in two steps:
1. A DNS domain name is retrieved for each combination of interface
and address family. A DOTS agent has to determine the domain in
which it is located relying on dynamic means such as DHCP
(Section 5) . Implementations may allow the user to specify a
default name that is used, if no specific name has been
configured.
2. Retrieved DNS domain names are then used for S-NAPTR lookups
[RFC3958]. Further DNS lookups may be necessary to determine the
peer DOTS agent IP address(es).
Once the DOTS agent has retrieved its DNS domain or discovered the
peer DOTS agent name that needs to be resolved (e.g., Section 5), an
S-NAPTR lookup with 'DOTS' application service and the desired
protocol tag is made to obtain information necessary to connect to
the authoritative peer DOTS agent within the given domain.
This specification defines "DOTS" and "DOTS-CALL-HOME" as application
service tags (Sections 9.3.1 and 9.3.2). It also defines
"signal.udp" (Section 9.3.3), "signal.tcp" (Section 9.3.4), and
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"data.tcp" (Section 9.3.5) as application protocol tags. An example
is provided in Figure 8.
In the example below, for domain 'example.net', the resolution
algorithm will result in IP address(es), port, tag and protocol
tuples as follows:
example.net.
IN NAPTR 100 10 "" DOTS:signal.udp "" signal.example.net.
IN NAPTR 200 10 "" DOTS:signal.tcp "" signal.example.net.
IN NAPTR 300 10 "" DOTS:data.tcp "" data.example.net.
signal.example.net.
IN NAPTR 100 10 "s" DOTS:signal.udp "" _dots._signal._udp.example.net.
IN NAPTR 200 10 "s" DOTS:signal.tcp "" _dots._signal._tcp.example.net.
data.example.net.
IN NAPTR 100 10 "s" DOTS:data.tcp "" _dots._data._tcp.example.net.
_dots._signal._udp.example.net.
IN SRV 0 0 5000 a.example.net.
_dots._signal._tcp.example.net.
IN SRV 0 0 5001 a.example.net.
_dots._data._tcp.example.net.
IN SRV 0 0 5002 a.example.net.
a.example.net.
IN AAAA 2001:db8::1
+-------+----------+-------------+------+--------+
| Order | Protocol | IP address | Port | Tag |
+-------+----------+-------------+------+--------+
| 1 | UDP | 2001:db8::1 | 5000 | Signal |
| 2 | TCP | 2001:db8::1 | 5001 | Signal |
| 3 | TCP | 2001:db8::1 | 5002 | Data |
+-------+----------+-------------+------+--------+
Figure 8: Sample Example
An example is provided in Figure 9 for the Call Home case.
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In the example below, for domain 'example.net', the resolution
algorithm will result in IP address(es), port, tag and protocol
tuples as follows:
example.net.
IN NAPTR 100 10 "" DOTS-CALL-HOME:signal.udp "" signal.example.net.
IN NAPTR 200 10 "" DOTS-CALL-HOME:signal.tcp "" signal.example.net.
signal.example.net.
IN NAPTR 100 10 "s" DOTS-CALL-HOME:signal.udp ""
_dots-call-home._signal._udp.example.net.
IN NAPTR 200 10 "s" DOTS-CALL-HOME:signal.tcp ""
_dots-call-home._signal._tcp.example.net.
_dots-call-home._signal._udp.example.net.
IN SRV 0 0 6000 b.example.net.
_dots-call-home._signal._tcp.example.net.
IN SRV 0 0 6001 b.example.net.
b.example.net.
IN AAAA 2001:db8::2
+-------+----------+-------------+------+--------+
| Order | Protocol | IP address | Port | Tag |
+-------+----------+-------------+------+--------+
| 1 | UDP | 2001:db8::2 | 6000 | Signal |
| 2 | TCP | 2001:db8::2 | 6001 | Signal |
+-------+----------+-------------+------+--------+
Figure 9: Sample Example for DOTS Signal Channel Call Home
If no DOTS-specific S-NAPTR records can be retrieved, the discovery
procedure fails for this domain name (and the corresponding interface
and IP protocol version). If more domain names are known, the
discovery procedure MAY perform the corresponding S-NAPTR lookups
immediately. However, before retrying a lookup that has failed, a
DOTS client MUST wait a time period that is appropriate for the
encountered error (e.g., NXDOMAIN, timeout, etc.).
7. DNS Service Discovery
DNS-based Service Discovery (DNS-SD) [RFC6763] provides generic
solutions for discovering services. DNS-SD defines a set of naming
rules for certain DNS record types that they use for advertising and
discovering services.
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Section 4.1 of [RFC6763] specifies that a service instance name in
DNS-SD has the following structure:
<Instance> . <Service> . <Domain>
The <Domain> portion specifies the DNS sub-domain where the service
instance is registered. It may be "local.", indicating the mDNS
local domain, or it may be a conventional domain name such as
"example.com.".
The <Service> portion of the DOTS service instance name MUST be
"_dots._signal._udp" or "_dots._signal._tcp" or "_dots._data._tcp" or
"_dots-call-home._signal._udp" or "_dots-call-home._signal._tcp".
8. Security Considerations
DOTS-related security considerations are discussed in Section 4 of
[I-D.ietf-dots-architecture] is to be considered. DOTS agents must
authenticate each other using (D)TLS before a DOTS session is
considered valid according to the [I-D.ietf-dots-signal-channel].
8.1. DHCP
The security considerations in [RFC2131] and [RFC8415] are to be
considered.
8.2. Service Resolution
The primary attack against the methods described in Section 6 is one
that would lead to impersonation of a peer DOTS agent. An attacker
could attempt to compromise the S-NAPTR resolution. The use of
mutual authentication makes it difficult to redirect a DOTS client
(or a Call Home DOTS server) to an illegitimate DOTS server (or a
Call Home DOTS client).
8.3. DNS Service Discovery
Since DNS-SD is a specification for how to name and use records in
the existing DNS system, it has no specific additional security
requirements over and above those that already apply to DNS queries
and DNS updates. For DNS queries, DNS Security Extensions (DNSSEC)
[RFC4033] SHOULD be used where the authenticity of information is
important. For DNS updates, secure updates [RFC2136][RFC3007] SHOULD
generally be used to control which clients have permission to update
DNS records.
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9. IANA Considerations
IANA is requested to allocate the SRV service name of "_dots._signal"
for DOTS signal channel over UDP or TCP, and the service name of
"_dots._data" for DOTS data channel over TCP.
9.1. DHCPv6 Option
IANA is requested to assign the following new DHCPv6 Option Code in
the registry maintained in: http://www.iana.org/assignments/
dhcpv6-parameters.
Value Description Client ORO Singleton Option
TBD1 OPTION_V6_DOTS_RI Yes Yes
TBD2 OPTION_V6_DOTS_ADDRESS Yes No
9.2. DHCPv4 Option
IANA is requested to assign the following new DHCPv4 Option Code in
the registry maintained in: http://www.iana.org/assignments/bootp-
dhcp-parameters/.
Option Name Value Data length Meaning
---------------------- ----- -------------------- -------------------
OPTION_V4_DOTS_RI TBA3 Variable; the Includes the name
maximum length is of the DOTS server.
255 octets.
OPTION_V4_DOTS_ADDRESS TBA4 Variable Includes one or
more DOTS IP
addresses.
9.3. Application Service & Application Protocol Tags
This document requests IANA to make the following allocations from
the registry available at: https://www.iana.org/assignments/s-naptr-
parameters/s-naptr-parameters.xhtml.
9.3.1. DOTS Application Service Tag Registration
o Application Protocol Tag: DOTS
o Intended Usage: See Section 6
o Security Considerations: See Section 8
o Contact Information: <one of the authors>
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9.3.2. DOTS Call Home Application Service Tag Registration
o Application Protocol Tag: DOTS-CALL-HOME
o Intended Usage: See Section 6
o Security Considerations: See Section 8
o Contact Information: <one of the authors>
9.3.3. signal.udp Application Protocol Tag Registration
o Application Protocol Tag: signal.udp
o Intended Usage: See Section 6
o Security Considerations: See Section 8
o Contact Information: <one of the authors>
9.3.4. signal.tcp Application Protocol Tag Registration
o Application Protocol Tag: signal.tcp
o Intended Usage: See Section 6
o Security Considerations: See Section 8
o Contact Information: <one of the authors>
9.3.5. data.tcp Application Protocol Tag Registration
o Application Protocol Tag: data.tcp
o Intended Usage: See Section 6
o Security Considerations: See Section 8
o Contact Information: <one of the authors>
10. Contributors
Prashanth Patil
Cisco Systems, Inc.
Email: praspati@cisco.com
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11. Acknowledgements
Thanks to Brian Carpenter for the review of the BRSKI text.
Many thanks to Russ White for the review, comments, and text
contribution.
Thanks for Dan Wing, Pei Wei, and Valery Smyslov for the review and
comments.
Thanks to Bernie Volz for the review of the DHCP section.
12. References
12.1. Normative References
[I-D.ietf-dots-signal-call-home]
K, R., Boucadair, M., and J. Shallow, "Distributed Denial-
of-Service Open Threat Signaling (DOTS) Signal Channel
Call Home", draft-ietf-dots-signal-call-home-05 (work in
progress), July 2019.
[I-D.ietf-dots-signal-channel]
K, R., Boucadair, M., Patil, P., Mortensen, A., and N.
Teague, "Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification", draft-
ietf-dots-signal-channel-37 (work in progress), July 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, DOI 10.17487/RFC2131, March 1997,
<https://www.rfc-editor.org/info/rfc2131>.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, DOI 10.17487/RFC2132, March 1997,
<https://www.rfc-editor.org/info/rfc2132>.
[RFC3396] Lemon, T. and S. Cheshire, "Encoding Long Options in the
Dynamic Host Configuration Protocol (DHCPv4)", RFC 3396,
DOI 10.17487/RFC3396, November 2002,
<https://www.rfc-editor.org/info/rfc3396>.
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[RFC3958] Daigle, L. and A. Newton, "Domain-Based Application
Service Location Using SRV RRs and the Dynamic Delegation
Discovery Service (DDDS)", RFC 3958, DOI 10.17487/RFC3958,
January 2005, <https://www.rfc-editor.org/info/rfc3958>.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <https://www.rfc-editor.org/info/rfc4291>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/info/rfc6763>.
[RFC6890] Cotton, M., Vegoda, L., Bonica, R., Ed., and B. Haberman,
"Special-Purpose IP Address Registries", BCP 153,
RFC 6890, DOI 10.17487/RFC6890, April 2013,
<https://www.rfc-editor.org/info/rfc6890>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A.,
Richardson, M., Jiang, S., Lemon, T., and T. Winters,
"Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 8415, DOI 10.17487/RFC8415, November 2018,
<https://www.rfc-editor.org/info/rfc8415>.
12.2. Informative References
[I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., and K.
Watsen, "Bootstrapping Remote Secure Key Infrastructures
(BRSKI)", draft-ietf-anima-bootstrapping-keyinfra-24 (work
in progress), July 2019.
[I-D.ietf-dots-architecture]
Mortensen, A., K, R., Andreasen, F., Teague, N., and R.
Compton, "Distributed-Denial-of-Service Open Threat
Signaling (DOTS) Architecture", draft-ietf-dots-
architecture-14 (work in progress), May 2019.
[I-D.ietf-dots-data-channel]
Boucadair, M. and R. K, "Distributed Denial-of-Service
Open Threat Signaling (DOTS) Data Channel Specification",
draft-ietf-dots-data-channel-31 (work in progress), July
2019.
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[I-D.ietf-dots-multihoming]
Boucadair, M., K, R., and W. Pan, "Multi-homing Deployment
Considerations for Distributed-Denial-of-Service Open
Threat Signaling (DOTS)", draft-ietf-dots-multihoming-02
(work in progress), July 2019.
[I-D.ietf-dots-use-cases]
Dobbins, R., Migault, D., Fouant, S., Moskowitz, R.,
Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS
Open Threat Signaling", draft-ietf-dots-use-cases-19 (work
in progress), July 2019.
[I-D.ietf-netconf-zerotouch]
Watsen, K., Abrahamsson, M., and I. Farrer, "Secure Zero
Touch Provisioning (SZTP)", draft-ietf-netconf-
zerotouch-29 (work in progress), January 2019.
[RFC2136] Vixie, P., Ed., Thomson, S., Rekhter, Y., and J. Bound,
"Dynamic Updates in the Domain Name System (DNS UPDATE)",
RFC 2136, DOI 10.17487/RFC2136, April 1997,
<https://www.rfc-editor.org/info/rfc2136>.
[RFC3007] Wellington, B., "Secure Domain Name System (DNS) Dynamic
Update", RFC 3007, DOI 10.17487/RFC3007, November 2000,
<https://www.rfc-editor.org/info/rfc3007>.
[RFC4033] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements",
RFC 4033, DOI 10.17487/RFC4033, March 2005,
<https://www.rfc-editor.org/info/rfc4033>.
[RFC6125] Saint-Andre, P. and J. Hodges, "Representation and
Verification of Domain-Based Application Service Identity
within Internet Public Key Infrastructure Using X.509
(PKIX) Certificates in the Context of Transport Layer
Security (TLS)", RFC 6125, DOI 10.17487/RFC6125, March
2011, <https://www.rfc-editor.org/info/rfc6125>.
[RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and
S. Krishnan, "Guidelines for Creating New DHCPv6 Options",
BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014,
<https://www.rfc-editor.org/info/rfc7227>.
Authors' Addresses
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Mohamed Boucadair
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Tirumaleswar Reddy
McAfee, Inc.
Embassy Golf Link Business Park
Bangalore, Karnataka 560071
India
Email: TirumaleswarReddy_Konda@McAfee.com
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