DOTS K. Nishizuka
Internet-Draft NTT Communications
Intended status: Standards Track M. Boucadair
Expires: September 3, 2020 Orange
T. Reddy
McAfee
T. Nagata
Lepidum
March 2, 2020
Controlling Filtering Rules Using Distributed Denial-of-Service Open
Threat Signaling (DOTS) Signal Channel
draft-ietf-dots-signal-filter-control-03
Abstract
This document specifies an extension to the DOTS signal channel
protocol so that DOTS clients can control their filtering rules when
an attack mitigation is active.
Particularly, this extension allows a DOTS client to activate or de-
activate existing filtering rules during a DDoS attack. The
characterization of these filtering rules is supposed to be conveyed
by a DOTS client during an idle time by means of the DOTS data
channel protocol.
Editorial Note (To be removed by RFC Editor)
Please update these statements within the document 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: Controlling Filtering Rules Using Distributed Denial-
of-Service Open Threat Signaling (DOTS) Signal Channel";
o reference: RFC XXXX
o [RFCXXXX]
Please update these statements with the RFC number to be assigned to
the following documents:
o "RFC SSSS: Distributed Denial-of-Service Open Threat Signaling
(DOTS) Signal Channel Specification" (used to be
[I-D.ietf-dots-signal-channel])
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o "RFC DDDD: Distributed Denial-of-Service Open Threat Signaling
(DOTS) Data Channel Specification" (used to be
[I-D.ietf-dots-data-channel])
Please update the "revision" date of the YANG module.
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
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This Internet-Draft will expire on September 3, 2020.
Copyright Notice
Copyright (c) 2020 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
(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
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described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. The Problem . . . . . . . . . . . . . . . . . . . . . . . 3
1.2. The Solution . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Controlling Filtering Rules of a DOTS Client . . . . . . . . 5
3.1. Binding DOTS Data and Signal Channels . . . . . . . . . . 5
3.2. DOTS Signal Channel Extension . . . . . . . . . . . . . . 6
3.2.1. Parameters and Behaviors . . . . . . . . . . . . . . 6
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3.2.2. DOTS Signal Filtering Control Module . . . . . . . . 10
3.2.2.1. Tree Structure . . . . . . . . . . . . . . . . . 10
3.2.2.2. YANG Module . . . . . . . . . . . . . . . . . . . 10
4. Sample Examples . . . . . . . . . . . . . . . . . . . . . . . 12
4.1. Conflict Handling . . . . . . . . . . . . . . . . . . . . 12
4.2. On-Demand Activation of an Accept-List Filter . . . . . . 17
4.3. DOTS Servers/Mitigators Lacking Capacity . . . . . . . . 18
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22
5.1. DOTS Signal Channel CBOR Mappings Registry . . . . . . . 22
5.2. DOTS Signal Filtering Control YANG Module . . . . . . . . 23
6. Security Considerations . . . . . . . . . . . . . . . . . . . 23
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 24
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 24
8.1. Normative References . . . . . . . . . . . . . . . . . . 24
8.2. Informative References . . . . . . . . . . . . . . . . . 25
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Introduction
1.1. The Problem
The DOTS data channel protocol [I-D.ietf-dots-data-channel] is used
for bulk data exchange between DOTS agents to improve the
coordination of parties involved in the response to the Distributed
Denial-of-Service (DDoS) attack. Filter management is one of its
tasks which enables a DOTS client to retrieve the filtering
capabilities of a DOTS server and to manage filtering rules.
Typically, these Filtering rules are used for dropping or rate-
limiting unwanted traffic, and permitting accept-listed traffic.
Unlike the DOTS signal channel protocol
[I-D.ietf-dots-signal-channel], the DOTS data channel protocol is not
expected to deal with attack conditions. As such, an issue that
might be encountered in some deployments is when filters installed by
means of the DOTS data channel protocol may not function as expected
during DDoS attacks or, worse, exacerbate an ongoing DDoS attack.
The DOTS data channel protocol cannot be used then to change these
filters, which may complicate DDoS mitigation operations [Interop].
A typical case is a DOTS client which configures during 'idle' time
(i.e., no mitigation is active) some filtering rules using the DOTS
data channel protocol to permit traffic from accept-listed sources,
but during a volumetric DDoS attack the DDoS mitigator identifies the
source addresses/prefixes in the accept-listed filtering rules are
attacking the target. For example, an attacker can spoof the IP
addresses of accept-listed sources to generate attack traffic or the
attacker can compromise the accept-listed sources and program them to
launch a DDoS attack.
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[I-D.ietf-dots-signal-channel] is designed so that the DDoS server
notifies the conflict to the DOTS client (that is, 'conflict-cause'
parameter set to 2 (Conflicts with an existing accept list)), but the
DOTS client may not be able to withdraw the accept-list rules during
the attack period due to the high-volume attack traffic saturating
the inbound link to the DOTS client domain. In other words, the DOTS
client cannot use the DOTS data channel protocol to withdraw the
accept-list filters when a DDoS attack is in progress. This assumes
that this DOTS client is the owner of the filtering rule.
1.2. The Solution
This specification addresses the problems discussed in Section 1.1 by
adding the capability of managing filtering rules using the DOTS
signal channel protocol, which enables a DOTS client to request the
activation (or deactivation) of filtering rules during a DDoS attack.
The DOTS signal channel protocol is designed to enable a DOTS client
to contact a DOTS server for help even under severe network
congestion conditions. Therefore, extending the DOTS signal channel
protocol to manage the filtering rules during an attack will enhance
the protection capability offered by DOTS protocols.
Note: The experiment at the IETF103 hackathon [Interop] showed
that even when the inbound link is saturated by DDoS attack
traffic, the DOTS client can signal mitigation requests using the
DOTS signal channel over the saturated link.
Conflicts that are induced by filters installed by other DOTS clients
of the same domain are not discussed in this specification.
An augment to the DOTS signal channel YANG module is defined in
Section 3.2.2.
Sample examples are provided in Section 4, in particular:
o Section 4.1 illustrates how the filter control extension is used
when conflicts with Access Control List (ACLs) are detected and
reported by a DOTS server.
o Section 4.2 shows how a DOTS client can instruct a DOTS server to
safely forward some specific traffic in 'attack' time.
o Section 4.3 shows how a DOTS client can react if the DDoS traffic
is still being forwarded to the DOTS client domain even if
mitigation requests were sent to a DOTS server.
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The JavaScript Object Notation (JSON) encoding of YANG-modeled data
[RFC7951] is used to illustrate the examples.
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 [RFC8612].
The terminology for describing YANG modules is defined in [RFC7950].
The meaning of the symbols in the tree diagram is defined in
[RFC8340].
3. Controlling Filtering Rules of a DOTS Client
3.1. Binding DOTS Data and Signal Channels
The filtering rules eventually managed using the DOTS signal channel
protocol are created a priori by the same DOTS client using the DOTS
data channel protocol. Managing conflicts with filters installed by
other DOTS clients of the same domain is out of scope.
As discussed in Section 4.4.1 of [I-D.ietf-dots-signal-channel], a
DOTS client must use the same 'cuid' for both the DOTS signal and
data channels. This requirement is meant to facilitate binding DOTS
channels used by the same DOTS client.
The DOTS signal and data channels from a DOTS client may or may not
use the same DOTS server. Nevertheless, the scope of the mitigation
request, alias, and filtering rules are not restricted to the DOTS
server but to the DOTS server domain. To that aim, DOTS servers
within a domain are assumed to have a mechanism to coordinate the
mitigation requests, aliases, and filtering rules to coordinate their
decisions for better mitigation operation efficiency. The exact
details about such mechanism is out of the scope of this document.
A filtering rule controlled by the DOTS signal channel is identified
by its ACL name (Section 7.2 of [I-D.ietf-dots-data-channel]). Note
that an ACL name unambiguously identifies an ACL bound to a DOTS
client, but the same name may be used by distinct DOTS clients.
The activation or deactivation of an ACL by the DOTS signal channel
overrides the 'activation-type' (defined in Section 7.2 of
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[I-D.ietf-dots-data-channel]) a priori conveyed with the filtering
rules using the DOTS data channel protocol.
3.2. DOTS Signal Channel Extension
3.2.1. Parameters and Behaviors
This specification extends the mitigation request defined in
Section 4.4.1 of [I-D.ietf-dots-signal-channel] to convey the
intended control of configured filtering rules. Concretely, the DOTS
client conveys 'acl-list' attribute with the following sub-attributes
in the CBOR body of a mitigation request (see the YANG-encoded
structure in Section 3.2.2.1):
acl-name: A name of an access list defined using the DOTS data
channel (Section 7.2 of [I-D.ietf-dots-data-channel]) that is
associated with the DOTS client.
As a reminder, an ACL is an ordered list of Access Control Entries
(ACE). Each Access Control Entry has a list of match criteria and
a list of actions [I-D.ietf-dots-data-channel]. The list of
configured ACLs can be retrieved using the DOTS data channel
during 'idle' time.
This is an optional attribute.
activation-type: Indicates the activation type of an ACL overriding
the existing 'activation-type' installed by the DOTS client using
the DOTS data channel.
As a reminder, this attribute can be set to 'deactivate',
'immediate', or 'activate-when-mitigating' as defined in
[I-D.ietf-dots-data-channel].
Note that both 'immediate' and 'activate-when-mitigating' have an
immediate effect when a mitigation request is being processed by
the DOTS server.
This is an optional attribute.
The JSON/YANG mappings for DOTS filter control attributes are shown
in Table 1.
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+-------------------+------------+--------+---------------+--------+
| Parameter Name | YANG | CBOR | CBOR Major | JSON |
| | Type | Key | Type & | Type |
| | | | Information | |
+-------------------+------------+--------+---------------+--------+
|ietf-dots-signal- | | | | |
|control:activation-| | | | |
| type | enumeration| TBA1 | 0 unsigned | String |
| | | | | |
|ietf-dots-signal- | | | | |
| control:acl-list | list | TBA2 | 4 array | Array |
| | | | | |
|ietf-dots-signal- | | | | |
| control:acl-name | leafref | TBA3 | 3 text string | String |
+-------------------+------------+--------+---------------+--------+
Table 1: JSON/YANG Mapping to CBOR for Filter Control Attributes
By default, ACL-related operations are achieved using the DOTS data
channel protocol when no attack is ongoing. DOTS clients MUST NOT
use the filtering control over DOTS signal channel in 'idle' time;
such requests MUST be discarded by DOTS servers with 4.00 (Bad
Request).
During an attack time, DOTS clients may include 'acl-list', 'acl-
name', and 'activation-type' attributes in a mitigation request.
This request may be the initial mitigation request for a given
mitigation scope or a new one overriding an existing request. In
both cases, a new 'mid' MUST be used. Nevertheless, it is NOT
RECOMMENDED to include ACL attributes in an initial mitigation
request for a given mitigation scope or in a mitigation request
adjusting the mitigation scope. This recommendation is meant to
avoid delaying attack mitigations because of failures to process ACL
attributes.
As the attack evolves, DOTS clients can adjust the 'activation-type'
of an ACL conveyed in a mitigation request or control other filters
as necessary. This can be achieved by sending a PUT request with a
new 'mid' value.
It is RECOMMENDED for a DOTS client to subscribe to asynchronous
notifications of the attack mitigation, as detailed in
Section 4.4.2.1 of [I-D.ietf-dots-signal-channel]. If not, the
polling mechanism in Section 4.4.2.2 of
[I-D.ietf-dots-signal-channel] has to be followed by the DOTS client.
A DOTS client relies on the information received from the DOTS server
and/or local information to the DOTS client domain to trigger a
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filter control request. Only filters that are pertinent for an
ongoing mitigation should be controlled by a DOTS client using the
DOTS signal channel.
'acl-list', 'acl-name', and 'activation-type' are defined as
comprehension-required parameters (Section 5.1). Following the rules
in Section 6 of [I-D.ietf-dots-signal-channel], if the DOTS server
does not understand the 'acl-list' or 'acl-name' or 'activation-type'
attributes, it responds with a "4.00 (Bad Request)" error response
code.
If the DOTS server does not find the ACL name ('acl-name') conveyed
in the mitigation request for this DOTS client, it MUST respond with
4.04 (Not Found) error response code.
If the DOTS server finds the ACL name for this DOTS client, and
assuming the request passed the validation checks in Section 4.4.1 of
[I-D.ietf-dots-signal-channel], the DOTS server MUST proceed with the
'activation-type' update. The update is immediately enforced by the
DOTS server and will be maintained as the new activation type for the
ACL name even after the termination of the mitigation request. In
addition, the DOTS server MUST update the lifetime of the
corresponding ACL similar to the update when a refresh request is
received using the DOTS data channel (Section 7.2 of
[I-D.ietf-dots-data-channel]). If, for some reason, the DOTS server
fails to apply the filter update, it MUST respond with 5.03 (Service
Unavailable) error response code and include the failed ACL update in
the diagnostic payload of the response (an example is shown in
Figure 1). Else, the DOTS server replies with the appropriate
response code defined in Section 4.4.1 of
[I-D.ietf-dots-signal-channel].
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{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"mid": 123,
"ietf-dots-signal-control:acl-list": [
{
"ietf-dots-signal-control:acl-name": "an-accept-list",
"ietf-dots-signal-control:activation-type": "deactivate"
}
]
}
]
}
}
Figure 1: Example of a Diagnostic Payload Including Failed ACL Update
If the DOTS client receives a 5.03 (Service Unavailable) with a
diagnostic payload indicating a failed ACL update as a response to an
initial mitigation or a mitigation with adjusted scope, the DOTS
client MUST immediately send a new request which repeats all the
parameters as sent in the failed mitigation request but without
including the ACL attributes. After the expiry of Max-Age returned
in the 5.03 (Service Unavailable) response, the DOTS client retries
with a new mitigation request (i.e., a new 'mid') that repeats all
the parameters as sent in the failed mitigation request.
If, during an active mitigation, the 'activation-type' is changed at
the DOTS server (e.g., as a result of an external action) for an ACL
bound to a DOTS client, the DOTS server notifies that DOTS client
with the change by including the corresponding ACL parameters in an
asynchronous notification (the DOTS client is observing the active
mitigation) or in a response to a polling request (Section 4.4.2.2 of
[I-D.ietf-dots-signal-channel]).
If the DOTS signal and data channels of a DOTS client are not
established with the same DOTS server of a DOTS server domain, the
above request processing operations are undertaken using the
coordination mechanism discussed in Section 3.1.
This specification does not require any modification to the efficacy
update and the withdrawal procedures defined in
[I-D.ietf-dots-signal-channel]. In particular, ACL-related clauses
are not included in a PUT request used to send an efficacy update and
DELETE requests.
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3.2.2. DOTS Signal Filtering Control Module
3.2.2.1. Tree Structure
This document augments the "ietf-dots-signal-channel" DOTS signal
YANG module defined in [I-D.ietf-dots-signal-channel] for managing
filtering rules.
This document defines the YANG module "ietf-dots-signal-control",
which has the following tree structure:
module: ietf-dots-signal-control
augment /ietf-signal:dots-signal/ietf-signal:message-type
/ietf-signal:mitigation-scope/ietf-signal:scope:
+--rw acl-list* [acl-name] {control-filtering}?
+--rw acl-name
| -> /ietf-data:dots-data/dots-client/acls/acl/name
+--rw activation-type? ietf-data:activation-type
3.2.2.2. YANG Module
This module uses types defined in [I-D.ietf-dots-data-channel].
<CODE BEGINS> file "ietf-dots-signal-control@2019-05-13.yang"
module ietf-dots-signal-control {
yang-version 1.1;
namespace
"urn:ietf:params:xml:ns:yang:ietf-dots-signal-control";
prefix signal-control;
import ietf-dots-signal-channel {
prefix ietf-signal;
reference
"RFC SSSS: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification";
}
import ietf-dots-data-channel {
prefix ietf-data;
reference
"RFC DDDD: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Data Channel Specification";
}
organization
"IETF DDoS Open Threat Signaling (DOTS) Working Group";
contact
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"WG Web: <https://datatracker.ietf.org/wg/dots/>
WG List: <mailto:dots@ietf.org>
Author: Kaname Nishizuka
<mailto:kaname@nttv6.jp>
Author: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Author: Konda, Tirumaleswar Reddy
<mailto:TirumaleswarReddy_Konda@McAfee.com>
Author: Takahiko Nagata
<mailto:nagata@lepidum.co.jp>";
description
"This module contains YANG definition for the signaling
messages exchanged between a DOTS client and a DOTS server
to control, by means of the DOTS signal channel, filtering
rules configured using the DOTS data channel.
Copyright (c) 2020 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 2019-05-13 {
description
"Initial revision.";
reference
"RFC XXXX: Controlling Filtering Rules Using Distributed
Denial-of-Service Open Threat Signaling (DOTS)
Signal Channel";
}
feature control-filtering {
description
"This feature means that the DOTS signal channel is able
to manage the filtering rules created by the same DOTS
client using the DOTS data channel.";
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}
augment "/ietf-signal:dots-signal/ietf-signal:message-type"
+ "/ietf-signal:mitigation-scope/ietf-signal:scope" {
if-feature control-filtering;
description "ACL name and activation type.";
list acl-list {
key "acl-name";
description
"List of ACLs as defined using the DOTS data
channel. ACLs bound to a DOTS client are uniquely
identified by a name.";
leaf acl-name {
type leafref {
path "/ietf-data:dots-data/ietf-data:dots-client"
+ "/ietf-data:acls/ietf-data:acl/ietf-data:name";
}
description
"Reference to the ACL name bound to a DOTS client.";
}
leaf activation-type {
type ietf-data:activation-type;
default "activate-when-mitigating";
description
"Sets the activation type of an ACL.";
}
}
}
}
<CODE ENDS>
4. Sample Examples
This section provides sample examples to illustrate the behavior
specified in Section 3.2.1. These examples are provided for
illustration purposes; they should not be considered as deployment
recommendations.
4.1. Conflict Handling
Let's consider a DOTS client which contacts its DOTS server during
'idle' time to install an accept-list allowing for UDP traffic issued
from 2001:db8:1234::/48 with a destination port number 443 to be
forwarded to 2001:db8:6401::2/127. It does so by sending, for
example, a PUT request shown in Figure 2.
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PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=an-accept-list HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "an-accept-list",
"type": "ipv6-acl-type",
"activation-type": "activate-when-mitigating",
"aces": {
"ace": [
{
"name": "test-ace-ipv6-udp",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/48"
},
"udp": {
"destination-port": {
"operator": "eq",
"port": 443
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 2: DOTS Data Channel Request to Create a Filter
Some time later, consider that a DDoS attack is detected by the DOTS
client on 2001:db8:6401::2/127. Consequently, the DOTS client sends
a mitigation request to its DOTS server as shown in Figure 3.
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Header: PUT (Code=0.03)
Uri-Path: ".well-known"
Uri-Path: "dots"
Uri-Path: "mitigate"
Uri-Path: "cuid=paL8p4Zqo4SLv64TLPXrxA"
Uri-Path: "mid=123"
Content-Format: "application/dots+cbor"
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"target-prefix": [
"2001:db8:6401::2/127"
],
"target-protocol": [
17
],
"lifetime": 3600
}
]
}
}
Figure 3: DOTS Signal Channel Mitigation Request
The DOTS server accepts immediately the request by replying with 2.01
(Created) (Figure 4 depicts the message body of the response).
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"mid": 123,
"lifetime": 3600
}
]
}
}
Figure 4: Status Response (Message Body)
Assuming the DOTS client subscribed to asynchronous notifications,
when the DOTS server concludes that some of the attack sources belong
to 2001:db8:1234::/48, it sends a notification message with 'status'
code set to '1 (Attack mitigation is in progress)' and 'conflict-
cause' set to '2' (conflict-with-acceptlist) to the DOTS client to
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indicate that this mitigation request is in progress, but a conflict
is detected.
Upon receipt of the notification message from the DOTS server, the
DOTS client sends a PUT request to deactivate the "an-accept-list"
ACL as shown in Figure 5.
The DOTS client can also decide to send a PUT request to deactivate
the "an-accept-list" ACL, if suspect traffic is received from an
accept-listed source (2001:db8:1234::/48). The structure of that PUT
is the same as the one shown in Figure 5.
Header: PUT (Code=0.03)
Uri-Path: ".well-known"
Uri-Path: "dots"
Uri-Path: "mitigate"
Uri-Path: "cuid=paL8p4Zqo4SLv64TLPXrxA"
Uri-Path: "mid=124"
Content-Format: "application/dots+cbor"
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"target-prefix": [
"2001:db8:6401::2/127"
],
"target-protocol": [
17
],
"ietf-dots-signal-control:acl-list": [
{
"ietf-dots-signal-control:acl-name": "an-accept-list",
"ietf-dots-signal-control:activation-type": "deactivate"
}
]
"lifetime": 3600
}
]
}
}
Figure 5: PUT for Deactivating a Conflicting Filter
Then, the DOTS server deactivates "an-accept-list" ACL and replies
with 2.04 (Changed) response to the DOTS client to confirm the
successful operation. The message body is similar to the one
depicted in Figure 4.
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Once the attack is mitigated, the DOTS client may use the data
channel to retrieve its ACLs maintained by the DOTS server. As shown
in Figure 6, the activation type is set to 'deactivate' as set by the
DOTS signal channel (Figure 5) instead of the type initially set
using the DOTS data channel (Figure 2).
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "an-accept-list",
"type": "ipv6-acl-type",
"activation-type": "deactivate",
"pending-lifetime": 10021,
"aces": {
"ace": [
{
"name": "test-ace-ipv6-udp",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/48"
},
"udp": {
"destination-port": {
"operator": "eq",
"port": 443
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 6: DOTS Data Channel GET Response after Mitigation (Message
Body)
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4.2. On-Demand Activation of an Accept-List Filter
Let's consider a DOTS client which contacts its DOTS server during
'idle' time to install an accept-list allowing for UDP traffic issued
from 2001:db8:1234::/48 to be forwarded to 2001:db8:6401::2/127. It
does so by sending, for example, a PUT request shown in Figure 7.
The DOTS server installs this filter with a "deactivated" state.
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=ioiuLoZqo4SLv64TLPXrxA/acls\
/acl=my-accept-list HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "my-accept-list",
"type": "ipv6-acl-type",
"activation-type": "deactivate",
"aces": {
"ace": [
{
"name": "an-ace",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/48",
"protocol": 17
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 7: DOTS Data Channel Request to Create an Accept-List Filter
Sometime later, consider that a UDP DDoS attack is detected by the
DOTS client on 2001:db8:6401::2/127 but the DOTS client wants to let
the traffic from 2001:db8:1234::/48 to be accept-listed to the DOTS
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client domain. Consequently, the DOTS client sends a mitigation
request to its DOTS server as shown in Figure 8.
Header: PUT (Code=0.03)
Uri-Path: ".well-known"
Uri-Path: "dots"
Uri-Path: "mitigate"
Uri-Path: "cuid=ioiuLoZqo4SLv64TLPXrxA"
Uri-Path: "mid=4879"
Content-Format: "application/dots+cbor"
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"target-prefix": [
"2001:db8:6401::2/127"
],
"target-protocol": [
17
],
"ietf-dots-signal-control:acl-list": [
{
"ietf-dots-signal-control:acl-name": "my-accept-list",
"ietf-dots-signal-control:activation-type": "immediate"
}
"lifetime": 3600
}
]
}
}
Figure 8: DOTS Signal Channel Mitigation Request with a Filter
Control
The DOTS server activates "my-accept-list" ACL and replies with 2.01
(Created) response to the DOTS client to confirm the successful
operation.
4.3. DOTS Servers/Mitigators Lacking Capacity
This section describes a scenario in which a DOTS client activates a
drop-list or a rate-limit filter during an attack.
Consider a DOTS client that contacts its DOTS server during 'idle'
time to install an accept-list that rate-limits all (or a part
thereof) traffic to be forwarded to 2001:db8:123::/48 as a last
resort countermeasure whenever required. It does so by sending, for
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example, a PUT request shown in Figure 9. The DOTS server installs
this filter with a "deactivated" state.
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=OopPisZqo4SLv64TLPXrxA/acls\
/acl=my-ratelimit-list HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "my-ratelimit-list",
"type": "ipv6-acl-type",
"activation-type": "deactivate",
"aces": {
"ace": [
{
"name": "my-ace",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:123::/48"
}
},
"actions": {
"forwarding": "accept",
"rate-limit": "20.00"
}
}
]
}
}
]
}
}
Figure 9: DOTS Data Channel Request to Create a Rate-Limit Filter
Consider now that a DDoS attack is detected by the DOTS client on
2001:db8:123::/48. Consequently, the DOTS client sends a mitigation
request to its DOTS server (Figure 10).
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Header: PUT (Code=0.03)
Uri-Path: ".well-known"
Uri-Path: "dots"
Uri-Path: "mitigate"
Uri-Path: "cuid=OopPisZqo4SLv64TLPXrxA"
Uri-Path: "mid=85"
Content-Format: "application/dots+cbor"
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"target-prefix": [
"2001:db8:123::/48"
],
"lifetime": 3600
}
]
}
}
Figure 10: DOTS Signal Channel Mitigation Request
For some reason (e.g., the DOTS server, or the mitigator, is lacking
a capability or capacity), the DOTS client is still receiving the
attack traffic which saturates available links. To soften the
problem, the DOTS client decides to activate the filter that rate-
limits the traffic destined to the DOTS client domain. To that aim,
the DOTS client sends the mitigation request to its DOTS server shown
in Figure 11.
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Header: PUT (Code=0.03)
Uri-Path: ".well-known"
Uri-Path: "dots"
Uri-Path: "mitigate"
Uri-Path: "cuid=OopPisZqo4SLv64TLPXrxA"
Uri-Path: "mid=86"
Content-Format: "application/dots+cbor"
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"target-prefix": [
"2001:db8:123::/48"
],
"ietf-dots-signal-control:acl-list": [
{
"ietf-dots-signal-control:acl-name": "my-ratelimit-list",
"ietf-dots-signal-control:activation-type": "immediate"
}
]
"lifetime": 3600
}
]
}
}
Figure 11: DOTS Signal Channel Mitigation Request to Activate a Rate-
Limit Filter
Then, the DOTS server activates "my-ratelimit-list" ACL and replies
with 2.04 (Changed) response to the DOTS client to confirm the
successful operation.
As the attack mitigation evolves, the DOTS client may decide to
deactivate the rate-limit policy (e.g., upon receipt of notification
status change from 'attack-exceeded-capability' to 'attack-
mitigation-in-progress'). Based on the mitigation status conveyed by
the DOTS server, the DOTS client can de-activate the rate-limit
action. ). It does so by sending the request shown in Figure 12.
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Header: PUT (Code=0.03)
Uri-Path: ".well-known"
Uri-Path: "dots"
Uri-Path: "mitigate"
Uri-Path: "cuid=OopPisZqo4SLv64TLPXrxA"
Uri-Path: "mid=87"
Content-Format: "application/dots+cbor"
{
"ietf-dots-signal-channel:mitigation-scope": {
"scope": [
{
"target-prefix": [
"2001:db8:123::/48"
],
"ietf-dots-signal-control:acl-list": [
{
"ietf-dots-signal-control:acl-name": "my-ratelimit-list",
"ietf-dots-signal-control:activation-type": "deactivate"
}
]
"lifetime": 3600
}
]
}
}
Figure 12: DOTS Signal Channel Mitigation Request to Deactivate a
Rate-Limit Filter
5. IANA Considerations
5.1. DOTS Signal Channel CBOR Mappings Registry
This specification registers the following parameters in the IANA
"DOTS Signal Channel CBOR Key Values" registry established by
[I-D.ietf-dots-signal-channel]
(https://www.iana.org/assignments/dots/dots.xhtml#dots-signal-
channel-cbor-key-values).
o Note to the RFC Editor: Please delete (TBA1-TBA2-TBA3) once the
CBOR key is assigned from the 1-16383 range. Please update
Table 1 accordingly.
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+--------------------+--------+-------+------------+---------------+
| Parameter Name | CBOR | CBOR | Change | Specification |
| | Key | Major | Controller | Document(s) |
| | Value | Type | | |
+--------------------+--------+-------+------------+---------------+
|ietf-dots-signal- | | | | |
|control:activation- | | | | |
| type | TBA1 | 0 | IESG | [RFCXXXX] |
|ietf-dots-signal- | | | | |
| control:acl-list | TBA2 | 4 | IESG | [RFCXXXX] |
|ietf-dots-signal- | | | | |
| control:acl-name | TBA3 | 3 | IESG | [RFCXXXX] |
+--------------------+--------+-------+------------+---------------+
5.2. DOTS Signal Filtering Control YANG Module
This document requests IANA to register the following URI in the "ns"
subregistry within the "IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:ietf-dots-signal-control
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
This document requests IANA to register the following YANG module in
the "YANG Module Names" subregistry [RFC7950] within the "YANG
Parameters" registry.
Name: ietf-dots-signal-control
Namespace: urn:ietf:params:xml:ns:yang:ietf-dots-signal-control
Maintained by IANA: N
Prefix: signal-control
Reference: RFC XXXX
6. Security Considerations
The security considerations discussed in
[I-D.ietf-dots-signal-channel] and [I-D.ietf-dots-data-channel] need
to be taken into account.
A DOTS client is entitled to access only to resources it creates. In
particular, a DOTS client can not tweak filtering rules created by
other DOTS clients of the same DOTS client domain.
A compromised DOTS client can use the filtering control capability to
exacerbate an ongoing attack. Likewise, such compromised DOTS client
may abstain from reacting to an ACL conflict notification received
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from the DOTS server during attacks. These are not new attack
vectors, but variations of threats discussed in
[I-D.ietf-dots-signal-channel] and [I-D.ietf-dots-data-channel].
DOTS operators should carefully monitor and audit DOTS agents to
detect misbehaviors and to deter misuses.
7. Acknowledgements
Many thanks to Wei Pan, Xia Liang, Jon Shallow, and Dan Wing for the
comments.
8. References
8.1. Normative References
[I-D.ietf-dots-data-channel]
Boucadair, M. and T. Reddy.K, "Distributed Denial-of-
Service Open Threat Signaling (DOTS) Data Channel
Specification", draft-ietf-dots-data-channel-31 (work in
progress), July 2019.
[I-D.ietf-dots-signal-channel]
Reddy.K, T., 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-41 (work in progress), January
2020.
[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>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
[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>.
[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>.
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8.2. Informative References
[Interop] Nishizuka, K., Shallow, J., and L. Xia , "DOTS Interop
test report, IETF 103 Hackathon", November 2018,
<https://datatracker.ietf.org/meeting/103/materials/
slides-103-dots-interop-report-from-ietf-103-hackathon-
00>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/info/rfc7951>.
[RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
<https://www.rfc-editor.org/info/rfc8340>.
[RFC8612] Mortensen, A., Reddy, T., and R. Moskowitz, "DDoS Open
Threat Signaling (DOTS) Requirements", RFC 8612,
DOI 10.17487/RFC8612, May 2019,
<https://www.rfc-editor.org/info/rfc8612>.
Authors' Addresses
Kaname Nishizuka
NTT Communications
GranPark 16F 3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
Email: kaname@nttv6.jp
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: kondtir@gmail.com
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Takahiko Nagata
Lepidum
Japan
Email: nagata@lepidum.co.jp
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