DOTS M. Boucadair, Ed.
Internet-Draft Orange
Intended status: Standards Track T. Reddy, Ed.
Expires: April 1, 2019 McAfee
K. Nishizuka
NTT Communications
L. Xia
Huawei
P. Patil
Cisco
A. Mortensen
Arbor Networks, Inc.
N. Teague
Verisign, Inc.
September 28, 2018
Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel
Specification
draft-ietf-dots-data-channel-22
Abstract
The document specifies a Distributed Denial-of-Service Open Threat
Signaling (DOTS) data channel used for bulk exchange of data that
cannot easily or appropriately communicated through the DOTS signal
channel under attack conditions.
This is a companion document to the DOTS signal channel
specification.
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: Distributed Denial-of-Service Open Threat Signaling
(DOTS) Data Channel Specification";
o reference: RFC XXXX
Please update these statements with the RFC number to be assigned to
the following documents:
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o "RFC YYYY: Distributed Denial-of-Service Open Threat Signaling
(DOTS) Signal Channel Specification" (used to be
[I-D.ietf-dots-signal-channel])
o "RFC ZZZZ: Network Access Control List (ACL) YANG Data Model"
(used to be [I-D.ietf-netmod-acl-model])
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
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 April 1, 2019.
Copyright Notice
Copyright (c) 2018 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
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5
3. DOTS Data Channel . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Design Overview . . . . . . . . . . . . . . . . . . . . . 6
3.2. DOTS Server(s) Discovery . . . . . . . . . . . . . . . . 8
3.3. NAT Considerations . . . . . . . . . . . . . . . . . . . 8
3.4. DOTS Gateways . . . . . . . . . . . . . . . . . . . . . . 8
3.5. Detect and Prevent Infinite Loops . . . . . . . . . . . . 9
3.6. Stale Entries . . . . . . . . . . . . . . . . . . . . . . 10
4. DOTS Data Channel YANG Module . . . . . . . . . . . . . . . . 10
4.1. Generic Tree Structure . . . . . . . . . . . . . . . . . 10
4.2. Filtering Fields . . . . . . . . . . . . . . . . . . . . 14
4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 21
5. Managing DOTS Clients . . . . . . . . . . . . . . . . . . . . 36
5.1. Registering DOTS Clients . . . . . . . . . . . . . . . . 36
5.2. Unregistering DOTS Clients . . . . . . . . . . . . . . . 39
6. Managing DOTS Aliases . . . . . . . . . . . . . . . . . . . . 40
6.1. Create Aliases . . . . . . . . . . . . . . . . . . . . . 40
6.2. Retrieve Installed Aliases . . . . . . . . . . . . . . . 44
6.3. Delete Aliases . . . . . . . . . . . . . . . . . . . . . 46
7. Managing DOTS Filtering Rules . . . . . . . . . . . . . . . . 46
7.1. Retrieve DOTS Filtering Capabilities . . . . . . . . . . 46
7.2. Install Filtering Rules . . . . . . . . . . . . . . . . . 48
7.3. Retrieve Installed Filtering Rules . . . . . . . . . . . 51
7.4. Remove Filtering Rules . . . . . . . . . . . . . . . . . 57
8. Operational Considerations . . . . . . . . . . . . . . . . . 58
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 58
10. Security Considerations . . . . . . . . . . . . . . . . . . . 59
11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 61
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 61
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 61
13.1. Normative References . . . . . . . . . . . . . . . . . . 61
13.2. Informative References . . . . . . . . . . . . . . . . . 62
Appendix A. Sample Examples: Filtering Fragments . . . . . . . . 64
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 66
1. Introduction
A distributed denial-of-service (DDoS) attack is an attempt to make
machines or network resources unavailable to their intended users.
In most cases, sufficient scale can be achieved by compromising
enough end-hosts and using those infected hosts to perpetrate and
amplify the attack. The victim of such attack can be an application
server, a router, a firewall, an entire network, etc.
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As discussed in [I-D.ietf-dots-requirements], the lack of a common
method to coordinate a real-time response among involved actors and
network domains inhibits the speed and effectiveness of DDoS attack
mitigation. From that standpoint, DDoS Open Threat Signaling (DOTS)
defines an architecture that allows a DOTS client to send requests to
a DOTS server for DDoS attack mitigation
[I-D.ietf-dots-architecture]. The DOTS approach is thus meant to
minimize the impact of DDoS attacks, thereby contributing to the
enforcement of more efficient defensive if not proactive security
strategies. To that aim, DOTS defines two channels: the signal and
the data channels (Figure 1).
+---------------+ +---------------+
| | <------- Signal Channel ------> | |
| DOTS Client | | DOTS Server |
| | <======= Data Channel ======> | |
+---------------+ +---------------+
Figure 1: DOTS Channels
The DOTS signal channel is used to carry information about a device
or a network (or a part thereof) that is under a DDoS attack. Such
information is sent by a DOTS client to an upstream DOTS server so
that appropriate mitigation actions are undertaken on traffic deemed
suspicious. The DOTS signal channel is further elaborated in
[I-D.ietf-dots-signal-channel].
As for the DOTS data channel, it is used for infrequent bulk data
exchange between DOTS agents to significantly improve the
coordination of all the parties involved in the response to the
attack. Section 2 of [I-D.ietf-dots-architecture] mentions that the
DOTS data channel is used to perform the following tasks:
o Creating aliases for resources for which mitigation may be
requested.
A DOTS client may submit to its DOTS server a collection of
prefixes which it would like to refer to by an alias when
requesting mitigation. The DOTS server can respond to this
request with either a success or failure response (see Section 2
in [I-D.ietf-dots-architecture]).
Refer to Section 6 for more details.
o Filter management, which enables a DOTS client to request the
installation or withdrawal of traffic filters, dropping or rate-
limiting unwanted traffic, and permitting white-listed traffic. A
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DOTS client is entitled to instruct filtering rules only on IP
resources that belong to its domain.
Sample use cases for populating black- or white-list filtering
rules are detailed hereafter:
* If a network resource (DOTS client) detects a potential DDoS
attack from a set of IP addresses, the DOTS client informs its
servicing DOTS gateway of all suspect IP addresses that need to
be blocked or black-listed for further investigation. The DOTS
client could also specify a list of protocols and port numbers
in the black-list rule.
The DOTS gateway then propagates the black-listed IP addresses
to a DOTS server which will undertake appropriate actions so
that traffic originated by these IP addresses to the target
network (specified by the DOTS client) is blocked.
* A network, that has partner sites from which only legitimate
traffic arrives, may want to ensure that the traffic from these
sites is not subjected to DDoS attack mitigation. The DOTS
client uses the DOTS data channel to convey the white-listed IP
prefixes of the partner sites to its DOTS server.
The DOTS server uses this information to white-list flows
originated by such IP prefixes and which reach the network.
Refer to Section 7 for more details.
2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
The reader should be familiar with the terms defined in
[I-D.ietf-dots-requirements].
The terminology for describing YANG modules is defined in [RFC7950].
The meaning of the symbols in tree diagrams is defined in [RFC8340].
This document generalizes the notion of Access Control List (ACL) so
that it is not device-specific [I-D.ietf-netmod-acl-model]. As such,
this document defines an ACL as an ordered set of rules that is used
to filter traffic. Each rule is represented by an Access Control
Entry (ACE). ACLs communicated via the DOTS data channel are not
bound to a device interface.
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For the sake of simplicity, all of the examples in this document use
"/restconf" as the discovered RESTCONF API root path. Many protocol
header lines and message-body text within examples throughout the
document are split into multiple lines for display purposes only.
When a line ends with backslash ('\') as the last character, the line
is wrapped for display purposes. It is to be considered to be joined
to the next line by deleting the backslash, the following line break,
and the leading whitespace of the next line.
3. DOTS Data Channel
3.1. Design Overview
Unlike the DOTS signal channel, which must remain operational even
when confronted with signal degradation due to packets loss, the DOTS
data channel is not expected to be fully operational at all times,
especially when a DDoS attack is underway. The requirements for a
DOTS data channel protocol are documented in
[I-D.ietf-dots-requirements].
This specification does not require an order of DOTS signal and data
channel creations nor mandates a time interval between them. These
considerations are implementation- and deployment-specific.
As the primary function of the data channel is data exchange, a
reliable transport mode is required in order for DOTS agents to
detect data delivery success or failure. This document uses RESTCONF
[RFC8040] over TLS over TCP as the DOTS data channel protocol. The
abstract layering of DOTS data channel is shown in Figure 2.
+-------------------+
| DOTS Data Channel |
+-------------------+
| RESTCONF |
+-------------------+
| TLS |
+-------------------+
| TCP |
+-------------------+
| IP |
+-------------------+
Figure 2: Abstract Layering of DOTS Data Channel
The HTTP POST, PUT, PATCH, and DELETE methods are used to edit data
resources represented by DOTS data channel YANG modules. These basic
edit operations allow the DOTS data channel running configuration to
be altered by a DOTS client.
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DOTS data channel configuration information as well as state
information can be retrieved with the GET method. An HTTP status-
line header field is returned for each request to report success or
failure for RESTCONF operations (Section 5.4 of [RFC8040]). The
"error-tag" provides more information about encountered errors
(Section 7 of [RFC8040]).
DOTS clients perform the root resource discovery procedure discussed
in Section 3.1 of [RFC8040] to determine the root of the RESTCONF
API. After discovering the RESTCONF API root, a DOTS client uses
this value as the initial part of the path in the request URI, in any
subsequent request to the DOTS server. The DOTS server may support
the retrieval of the YANG modules it supports (Section 3.7 in
[RFC8040]). For example, a DOTS client may use RESTCONF to retrieve
the vendor-specific YANG modules supported by its DOTS server.
JavaScript Object Notation (JSON) [RFC8259] payload is used to
propagate the DOTS data channel specific payload messages that carry
request parameters and response information, such as errors. This
specification uses the encoding rules defined in [RFC7951] for
representing DOTS data channel configuration data using YANG
(Section 4) as JSON text.
A DOTS client registers itself to its DOTS server(s) in order to set
up DOTS data channel-related configuration data and receive state
data (i.e., non-configuration data) from the DOTS server(s)
(Section 5). Mutual authentication and coupling of signal and data
channels are specified in [I-D.ietf-dots-signal-channel].
A single DOTS data channel between DOTS agents can be used to
exchange multiple requests and multiple responses. To reduce DOTS
client and DOTS server workload, DOTS clients SHOULD re-use the same
TLS session. While the communication to the DOTS server is
quiescent, the DOTS client MAY probe the server to ensure it has
maintained cryptographic state. Such probes can also keep alive
firewall and/or NAT bindings. A TLS heartbeat [RFC6520] verifies
that the DOTS server still has TLS state by returning a TLS message.
A DOTS server may detect conflicting filtering requests from distinct
DOTS clients which belong to the same domain. For example, a DOTS
client could request to blacklist a prefix by specifying the source
prefix, while another DOTS client could request to whitelist that
same source prefix, but both having the same destination prefix. It
is out of scope of this specification to recommend the behavior to
follow for handling conflicting requests (e.g., reject all, reject
the new request, notify an administrator for validation). DOTS
servers SHOULD support a configuration parameter to indicate the
behavior to follow when a conflict is detected. Section 7.2
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specifies the behavior when no instruction is supplied to a DOTS
server.
How filtering rules instantiated on a DOTS server are translated into
network configurations actions is out of scope.
3.2. DOTS Server(s) Discovery
This document assumes that DOTS clients are provisioned with the
reachability information of their DOTS server(s) using a variety of
means (e.g., local configuration, or dynamic means such as DHCP).
The specification of such means are out of scope of this document.
Likewise, it is out of scope of this document to specify the behavior
to be followed by a DOTS client to send DOTS requests when multiple
DOTS servers are provisioned (e.g., contact all DOTS servers, select
one DOTS server among the list).
3.3. NAT Considerations
In deployments where one or more translators (e.g., NAT44, NAT64,
NPTv6) are enabled between the client's network and the DOTS server,
DOTS data channel messages forwarded to a DOTS server MUST NOT
include internal IP addresses/prefixes and/or port numbers; external
addresses/prefixes and/or port numbers as assigned by the translator
MUST be used instead. This document does not make any recommendation
about possible translator discovery mechanisms. The following are
some (non-exhaustive) deployment examples that may be considered:
o Port Control Protocol (PCP) [RFC6887] or Session Traversal
Utilities for NAT (STUN) [RFC5389] may be used to retrieve the
external addresses/prefixes and/or port numbers. Information
retrieved by means of PCP or STUN will be used to feed the DOTS
data channel messages that will be sent to a DOTS server.
o A DOTS gateway may be co-located with the translator. The DOTS
gateway will need to update the DOTS messages, based upon the
local translator's binding table.
3.4. DOTS Gateways
When a server-domain DOTS gateway is involved in DOTS data channel
exchanges, the same considerations for manipulating the 'cdid'
(client domain identifier) parameter specified in
[I-D.ietf-dots-signal-channel] MUST be followed by DOTS agents. As a
reminder, 'cdid' is meant to assist the DOTS server to enforce some
policies (e.g., limit the number of filtering rules per DOTS client
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or per DOTS client domain). A loop detect mechanism for DOTS
gateways is specified in Section 3.5.
If a DOTS gateway is involved, the DOTS gateway verifies that the
DOTS client is authorized to undertake a data channel action (e.g.,
instantiate filtering rules). If the DOTS client is authorized, it
propagates the rules to the upstream DOTS server. Likewise, the DOTS
server verifies that the DOTS gateway is authorized to relay data
channel actions. For example, to create or purge filters, a DOTS
client sends its request to its DOTS gateway. The DOTS gateway
validates the rules in the request and proxies the requests
containing the filtering rules to its DOTS server. When the DOTS
gateway receives the associated response from the DOTS server, it
propagates the response back to the DOTS client.
3.5. Detect and Prevent Infinite Loops
In order to detect and prevent infinite loops, DOTS gateways MUST
support the procedure defined in Section 5.7.1 of [RFC7230]. In
particular, each intermediate DOTS gateway MUST check that none of
its own information (e.g., server names, literal IP addresses) is
present in the "Via" header of a DOTS message it receives:
o If it detects that its own information is present in the "Via"
header, the DOTS gateway MUST NOT forward the DOTS message.
Messages that cannot be forwarded because of a loop SHOULD be
logged with a "508 Loop Detected" status-line returned sent back
to the DOTS peer. The structure of the reported error is depicted
in Figure 3.
error-tag: loop-detected
error-type: transport, application
error-severity: error
error-info: <via-header> : A copy of the Via header when
the loop was detected.
Description: An infinite loop has been detected when forwarding
a requests via a proxy.
Figure 3: Loop Detected Error
It is RECOMMENDED that DOTS clients and gateways support means to
alert administrators about loop errors so that appropriate actions
are undertaken.
o Otherwise, the DOTS agent MUST update or insert the "Via" header
by appending its own information.
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Unless configured otherwise, DOTS gateways at the boundaries of a
DOTS client domain SHOULD remove the previous "Via" header
information after checking for a loop before forwarding. This
behavior is required for topology hiding purposes but also to
minimize potential conflicts that may arise if overlapping
information is used in distinct DOTS domains (e.g., private IPv4
addresses, non globally unique aliases).
3.6. Stale Entries
In order to avoid stale entries, a lifetime is associated with alias
and filtering entries created by DOTS clients. Also, DOTS servers
may track the inactivity timeout of DOTS clients to detect stale
entries.
4. DOTS Data Channel YANG Module
4.1. Generic Tree Structure
The DOTS data channel YANG module (ietf-dots-data-channel) provides a
method for DOTS clients to manage aliases for resources for which
mitigation may be requested. Such aliases may be used in subsequent
DOTS signal channel exchanges to refer more efficiently to the
resources under attack.
The tree structure for the DOTS alias is depicted in Figure 4.
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module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| +--rw cuid string
| +--rw cdid? string
| +--rw aliases
| | +--rw alias* [name]
| | +--rw name string
| | +--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 target-fqdn* inet:domain-name
| | +--rw target-uri* inet:uri
| | +--ro pending-lifetime? int32
| +--rw acls
| ...
+--ro capabilities
...
Figure 4: DOTS Alias Subtree
Also, the 'ietf-dots-data-channel' module provides a method for DOTS
clients to manage filtering rules. Examples of filtering management
in a DOTS context include, but not limited to:
o Black-list management, which enables a DOTS client to inform a
DOTS server about sources from which traffic should be discarded.
o White-list management, which enables a DOTS client to inform a
DOTS server about sources from which traffic should always be
accepted.
o Filter management, which enables a DOTS client to request the
installation or withdrawal of traffic filters, dropping or rate-
limiting unwanted traffic and permitting white-listed traffic.
The tree structure for the DOTS filtering entries is depicted in
Figure 5.
Early versions of this document investigated to what extent
augmenting 'ietf-access-control-list' meet DOTS requirements, but
that design approach was abandoned because it does not support
meeting many of DOTS requirements, e.g.,
o Retrieve a filtering entry (or all entries) created by a DOTS
client.
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o Delete a filtering entry that was instantiated by a DOTS client.
DOTS filtering entries (i.e., Access Control List (ACL)) mimic the
structure specified in [I-D.ietf-netmod-acl-model]. Concretely, DOTS
agents are assumed to manipulate an ordered list of ACLs; each ACL
contains a separately ordered list of Access Control Entries (ACEs).
Each ACE has a group of match and a group of action criteria.
Once all the ACE entries have been iterated though with no match,
then all the following ACL's ACE entries are iterated through until
the first match at which point the specified action is applied. If
there is no match, then there is no action to be taken against the
packet.
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module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| +--rw cuid string
| +--rw cdid? string
| +--rw aliases
| | ...
| +--rw acls
| +--rw acl* [name]
| +--rw name string
| +--rw type? ietf-acl:acl-type
| +--rw activation-type? enumeration
| +--ro pending-lifetime? int32
| +--rw aces
| +--rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | +--:(ipv4)
| | | | ...
| | | +--:(ipv6)
| | | ...
| | +--rw (l4)?
| | +--:(tcp)
| | | ...
| | +--:(udp)
| | | ...
| | +--:(icmp)
| | ...
| +--rw actions
| | +--rw forwarding identityref
| | +--rw rate-limit? decimal64
| +--ro statistics
| +--ro matched-packets? yang:counter64
| +--ro matched-octets? yang:counter64
+--ro capabilities
...
Figure 5: DOTS ACLs Subtree
Filtering rules instructed by a DOTS client assumes a default
direction: the destination is the DOTS client domain.
DOTS forwarding actions can be 'accept' (i.e., accept matching
traffic) or 'drop' (i.e., drop matching traffic without sending any
ICMP error message). Accepted traffic can be subject to rate
limiting 'rate-limit'. Note that 'reject' action (i.e., drop
matching traffic and send an ICMP error message to the source) is not
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supported in 'ietf-dots-data-channel' because it is not appropriate
in the context of DDoS mitigation. Generating ICMP messages to
notify drops when mitigating a DDoS attack will exacerbate the DDoS
attack. Furthermore, these ICMP messages will be used by an attacker
as an explicit signal that the traffic is being blocked.
4.2. Filtering Fields
The 'ietf-dots-data-channel' module reuses the packet fields module
'ietf-packet-fields' [I-D.ietf-netmod-acl-model] which defines
matching on fields in the packet including IPv4, IPv6, and transport
layer fields.
This specification defines a new IPv4/IPv6 matching field called
'fragment' to efficiently handle fragment-related filtering rules.
Indeed, [I-D.ietf-netmod-acl-model] does not support such capability
for IPv6 but offers a partial support for IPv4 by means of 'flags'.
Nevertheless, the use of 'flags' is problematic since it does not
allow to define a bitmask. For example, setting other bits not
covered by the 'flags' filtering clause in a packet will allow that
packet to get through (because it won't match the ACE). Sample
examples to illustrate how 'fragment' can be used are provided in
Appendix A.
Figure 6 shows the IPv4 match subtree.
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module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| ...
| +--rw acls
| +--rw acl* [name]
| ...
| +--rw aces
| +--rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | +--:(ipv4)
| | | | +--rw ipv4
| | | | +--rw dscp? inet:dscp
| | | | +--rw ecn? uint8
| | | | +--rw length? uint16
| | | | +--rw ttl? uint8
| | | | +--rw protocol? uint8
| | | | +--rw ihl? uint8
| | | | +--rw flags? bits
| | | | +--rw offset? uint16
| | | | +--rw identification? uint16
| | | | +--rw (destination-network)?
| | | | | +--:(destination-ipv4-network)
| | | | | +--rw destination-ipv4-network?
| | | | | inet:ipv4-prefix
| | | | +--rw (source-network)?
| | | | | +--:(source-ipv4-network)
| | | | | +--rw source-ipv4-network?
| | | | | inet:ipv4-prefix
| | | | +--rw fragment
| | | | +--rw operator? operator
| | | | +--rw type fragment-type
| | | +--:(ipv6)
| | | ...
| | +--rw (l4)?
| | ...
| +--rw actions
| | ...
| +--ro statistics
| ...
+--ro capabilities
...
Figure 6: DOTS ACLs Subtree (IPv4 Match)
Figure 7 shows the IPv6 match subtree.
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module: ietf-dots-data-channel
+--rw dots-data
+--rw dots-client* [cuid]
| ...
| +--rw acls
| +--rw acl* [name]
| ...
| +--rw aces
| +--rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | +--:(ipv4)
| | | | ...
| | | +--:(ipv6)
| | | +--rw ipv6
| | | +--rw dscp? inet:dscp
| | | +--rw ecn? uint8
| | | +--rw length? uint16
| | | +--rw ttl? uint8
| | | +--rw protocol? uint8
| | | +--rw (destination-network)?
| | | | +--:(destination-ipv6-network)
| | | | +--rw destination-ipv6-network?
| | | | inet:ipv6-prefix
| | | +--rw (source-network)?
| | | | +--:(source-ipv6-network)
| | | | +--rw source-ipv6-network?
| | | | inet:ipv6-prefix
| | | +--rw flow-label?
| | | | inet:ipv6-flow-label
| | | +--rw fragment
| | | +--rw operator? operator
| | | +--rw type fragment-type
| | +--rw (l4)?
| | ...
| +--rw actions
| | ...
| +--ro statistics
| ...
+--ro capabilities
...
Figure 7: DOTS ACLs Subtree (IPv6 Match)
Figure 8 shows the TCP match subtree. In addition to the fields
defined in [I-D.ietf-netmod-acl-model], this specification defines a
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new TCP matching field, called 'flags-bitmask', to efficiently handle
TCP flags filtering rules.
module: ietf-dots-data-channel
+--rw dots-data
+-rw dots-client* [cuid]
| ...
| +-rw acls
| +-rw acl* [name]
| ...
| +-rw aces
| +-rw ace* [name]
| +-rw name string
| +-rw matches
| | +-rw (l3)?
| | | ...
| | +-rw (l4)?
| | +-:(tcp)
| | | +-rw tcp
| | | +--rw sequence-number? uint32
| | | +--rw acknowledgement-number? uint32
| | | +--rw data-offset? uint8
| | | +--rw reserved? uint8
| | | +--rw flags? bits
| | | +--rw window-size? uint16
| | | +--rw urgent-pointer? uint16
| | | +--rw options? uint32
| | | +--rw flags-bitmask
| | | | +--rw operator? operator
| | | | +--rw bitmask uint16
| | | +--rw (source-port)?
| | | | +--:(source-port-range-or-operator)
| | | | +--rw source-port-range-or-operator
| | | | +--rw (port-range-or-operator)?
| | | | +--:(range)
| | | | | +--rw lower-port
| | | | | | inet:port-number
| | | | | +--rw upper-port
| | | | | inet:port-number
| | | | +--:(operator)
| | | | +--rw operator?
| | | | | operator
| | | | +--rw port
| | | | inet:port-number
| | | +--rw (destination-port)?
| | | +--:(destination-port-range-or-operator)
| | | +--rw destination-port-range-or-operator
| | | +--rw (port-range-or-operator)?
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| | | +--:(range)
| | | | +--rw lower-port
| | | | | inet:port-number
| | | | +--rw upper-port
| | | | inet:port-number
| | | +--:(operator)
| | | +--rw operator?
| | | | operator
| | | +--rw port
| | | inet:port-number
| | +-:(udp)
| | | ...
| | +-:(icmp)
| | ...
| +-rw actions
| | ...
| +-ro statistics
| ...
+-ro capabilities
...
Figure 8: DOTS ACLs Subtree (TCP Match)
Figure 9 shows the UDP and ICMP match subtrees.
module: ietf-dots-data-channel
+-rw dots-data
+-rw dots-client* [cuid]
| ...
| +-rw acls
| +-rw acl* [name]
| ...
| +-rw aces
| +-rw ace* [name]
| +--rw name string
| +--rw matches
| | +--rw (l3)?
| | | ...
| | +--rw (l4)?
| | +--:(tcp)
| | | ...
| | +--:(udp)
| | | +--rw udp
| | | +--rw length? uint16
| | | +--rw (source-port)?
| | | | +--:(source-port-range-or-operator)
| | | | +--rw source-port-range-or-operator
| | | | +--rw (port-range-or-operator)?
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| | | | +--:(range)
| | | | | +--rw lower-port
| | | | | | inet:port-number
| | | | | +--rw upper-port
| | | | | inet:port-number
| | | | +--:(operator)
| | | | +--rw operator?
| | | | | operator
| | | | +--rw port
| | | | inet:port-number
| | | +--rw (destination-port)?
| | | +--:(destination-port-range-or-operator)
| | | +--rw destination-port-range-or-operator
| | | +--rw (port-range-or-operator)?
| | | +--:(range)
| | | | +--rw lower-port
| | | | | inet:port-number
| | | | +--rw upper-port
| | | | inet:port-number
| | | +--:(operator)
| | | +--rw operator?
| | | | operator
| | | +--rw port
| | | inet:port-number
| | +--:(icmp)
| | +--rw icmp
| | +--rw type? uint8
| | +--rw code? uint8
| | +--rw rest-of-header? uint32
| +--rw actions
| | ...
| +--ro statistics
| ...
+-ro capabilities
...
Figure 9: DOTS ACLs Subtree (UDP and ICMP Match)
DOTS implementations MUST support the following matching criteria:
match based on the IP header (IPv4 and IPv6), match based on the
transport header (TCP, UDP, and ICMP), and any combination
thereof. The same matching fields are used for both ICMP and
ICMPv6.
The following match fields MUST be supported by DOTS implementations
(Table 1):
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ACL Mandatory Fields
Match
------- -------------------------------------------------------------
ipv4 length, protocol, destination-ipv4-network, source-
ipv4-network, and fragment
ipv6 length, protocol, destination-ipv6-network, source-
ipv6-network, and fragment
tcp flags-bitmask, source-port-range-or-operator, and
destination-port-range-or-operator
udp length, source-port-range-or-operator, and destination-port-
range-or-operator
icmp type and code
Table 1: Mandatory DOTS Channel Match Fields
Implementations MAY support other filtering match fields and actions.
The 'ietf-dots-data-channel' provides a method for an implementation
to expose its filtering capabilities. The tree structure of the
'capabilities' is shown in Figure 10.
module: ietf-dots-data-channel
+--rw dots-data
...
+--ro capabilities
+--ro address-family* enumeration
+--ro forwarding-actions* identityref
+--ro rate-limit? boolean
+--ro transport-protocols* uint8
+--ro ipv4
| +--ro dscp? boolean
| +--ro ecn? boolean
| +--ro length? boolean
| +--ro ttl? boolean
| +--ro protocol? boolean
| +--ro ihl? boolean
| +--ro flags? boolean
| +--ro offset? boolean
| +--ro identification? boolean
| +--ro source-prefix? boolean
| +--ro destination-prefix? boolean
| +--ro fragment? boolean
+--ro ipv6
| +--ro dscp? boolean
| +--ro ecn? boolean
| +--ro flow-label? boolean
| +--ro length? boolean
| +--ro protocol? boolean
| +--ro hoplimit? boolean
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| +--ro source-prefix? boolean
| +--ro destination-prefix? boolean
| +--ro fragment? boolean
+--ro tcp
| +--ro sequence-number? boolean
| +--ro acknowledgement-number? boolean
| +--ro data-offset? boolean
| +--ro reserved? boolean
| +--ro flags? boolean
| +--ro flags-bitmask? boolean
| +--ro window-size? boolean
| +--ro urgent-pointer? boolean
| +--ro options? boolean
| +--ro source-port? boolean
| +--ro destination-port? boolean
| +--ro port-range? boolean
+--ro udp
| +--ro length? boolean
| +--ro source-port? boolean
| +--ro destination-port? boolean
| +--ro port-range? boolean
+--ro icmp
+--ro type? boolean
+--ro code? boolean
+--ro rest-of-header? boolean
Figure 10: Filtering Capabilities Subtree
4.3. YANG Module
<CODE BEGINS> file "ietf-dots-data-channel@2018-07-25.yang"
module ietf-dots-data-channel {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-dots-data-channel";
prefix data-channel;
import ietf-access-control-list {
prefix ietf-acl;
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
}
import ietf-packet-fields {
prefix packet-fields;
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
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}
import ietf-dots-signal-channel {
prefix dots-signal;
reference
"RFC YYYY: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification";
}
organization
"IETF DDoS Open Threat Signaling (DOTS) Working Group";
contact
"WG Web: <https://datatracker.ietf.org/wg/dots/>
WG List: <mailto:dots@ietf.org>
Editor: Mohamed Boucadair
<mailto:mohamed.boucadair@orange.com>
Editor: Konda, Tirumaleswar Reddy
<mailto:TirumaleswarReddy_Konda@McAfee.com>
Author: Jon Shallow
<mailto:jon.shallow@nccgroup.com>
Author: Kaname Nishizuka
<mailto:kaname@nttv6.jp>
Author: Liang Xia
<mailto:frank.xialiang@huawei.com>
Author: Prashanth Patil
<mailto:praspati@cisco.com>
Author: Andrew Mortensen
<mailto:amortensen@arbor.net>
Author: Nik Teague
<mailto:nteague@verisign.com>";
description
"This module contains YANG definition for configuring
aliases for resources and filtering rules using DOTS
data channel.
Copyright (c) 2018 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
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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 2018-07-25 {
description
"Initial revision.";
reference
"RFC XXXX: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Data Channel Specification";
}
typedef operator {
type bits {
bit not {
position 0;
description
"If set, logical negation of operation.";
}
bit match {
position 1;
description
"Match bit. If set, this is a bitwise match operation
defined as '(data & value) == value'; if unset, (data &
value) evaluates to TRUE if any of the bits in the value
mask are set in the data.";
}
}
description
"How to apply the defined bitmask.";
}
grouping tcp-flags {
leaf operator {
type operator;
default match;
description
"How to interpret the TCP flags.";
}
leaf bitmask {
type uint16;
mandatory true;
description
"Bitmask values can be encoded as a 1- or 2-byte bitmask.
When a single byte is specified, it matches byte 13
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of the TCP header, which contains bits 8 though 15
of the 4th 32-bit word. When a 2-byte encoding is used,
it matches bytes 12 and 13 of the TCP header with
the data offset field having a 'don't care' value.";
}
description
"Operations on TCP flags.";
}
typedef fragment-type {
type bits {
bit df {
position 0;
description
"Don't fragment bit for IPv4.
This bit must be set to 0 for IPv6.";
}
bit isf {
position 1;
description
"Is a fragment.";
}
bit ff {
position 2;
description
"First fragment.";
}
bit lf {
position 3;
description
"Last fragment.";
}
}
description
"Different fragment types to match against.";
}
grouping fragment-fields {
leaf operator {
type operator;
default match;
description
"How to interpret the fragment type.";
}
leaf type {
type fragment-type;
mandatory true;
description
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"What fragment type to look for.";
}
description
"Operations on fragment types.";
}
grouping aliases {
description
"Top level container for aliases";
list alias {
key "name";
description
"List of aliases";
leaf name {
type string;
description
"The name of the alias";
}
uses dots-signal:target;
leaf pending-lifetime {
type int32;
units "minutes";
config false;
description
"Indicates the pending validity lifetime of the alias
entry.";
}
}
}
grouping ports {
choice source-port {
container source-port-range-or-operator {
uses packet-fields:port-range-or-operator;
description
"Source port definition.";
}
description
"Choice of specifying the source port or referring to
a group of source ports.";
}
choice destination-port {
container destination-port-range-or-operator {
uses packet-fields:port-range-or-operator;
description
"Destination port definition.";
}
description
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"Choice of specifying a destination port or referring
to a group of destination ports.";
}
description
"Choice of specifying a source or destination ports.";
}
grouping access-lists {
description
"Specifies the ordered set of Access Control Lists.";
list acl {
key "name";
ordered-by user;
description
"An Access Control List (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.";
leaf name {
type string {
length "1..64";
}
description
"The name of the access list.";
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
}
leaf type {
type ietf-acl:acl-type;
description
"Type of access control list. Indicates the primary intended
type of match criteria (e.g., IPv4, IPv6) used in the list
instance.";
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
}
leaf activation-type {
type enumeration {
enum "activate-when-mitigating" {
value 1;
description
"The ACL is installed only when a mitigation is active.
The ACL is specific to this DOTS client.";
}
enum "immediate" {
value 2;
description
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"The ACL is immediately activated.";
}
}
description
"Indicates whether an ACL is to be installed immediately
or when a mitigation is active.";
}
leaf pending-lifetime {
type int32;
units "minutes";
config false;
description
"Indicates the pending validity lifetime of the alias
entry.";
}
container aces {
description
"The Access Control Entries container contains
a list of ACEs.";
list ace {
key "name";
ordered-by user;
description
"List of access list entries.";
leaf name {
type string {
length "1..64";
}
description
"A unique name identifying this Access List
Entry (ACE).";
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
}
container matches {
description
"The rules in this set determine what fields will be
matched upon before any action is taken on them.
If no matches are defined in a particular container,
then any packet will match that container.
If no matches are specified at all in an ACE, then any
packet will match the ACE.";
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
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choice l3 {
container ipv4 {
when "derived-from(../../../../type," +
"'ietf-acl:ipv4-acl-type')";
uses packet-fields:acl-ip-header-fields;
uses packet-fields:acl-ipv4-header-fields;
container fragment {
description
"Indicates how to handle IPv4 fragments.";
uses fragment-fields;
}
description
"Rule set that matches IPv4 header.";
}
container ipv6 {
when "derived-from(../../../../type," +
"'ietf-acl:ipv6-acl-type')";
uses packet-fields:acl-ip-header-fields;
uses packet-fields:acl-ipv6-header-fields;
container fragment {
description
"Indicates how to handle IPv6 fragments.";
uses fragment-fields;
}
description
"Rule set that matches IPv6 header.";
}
description
"Either IPv4 or IPv6.";
}
choice l4 {
container tcp {
uses packet-fields:acl-tcp-header-fields;
container flags-bitmask {
description
"Indicates how to handle TCP flags.";
uses tcp-flags;
}
uses ports;
description
"Rule set that matches TCP header.";
}
container udp {
uses packet-fields:acl-udp-header-fields;
uses ports;
description
"Rule set that matches UDP header.";
}
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container icmp {
uses packet-fields:acl-icmp-header-fields;
description
"Rule set that matches ICMP/ICMPv6 header.";
}
description
"Can be TCP, UDP, or ICMP/ICMPv6";
}
}
container actions {
description
"Definitions of action for this ACE.";
leaf forwarding {
type identityref {
base ietf-acl:forwarding-action;
}
mandatory true;
description
"Specifies the forwarding action per ACE.";
reference
"RFC ZZZZ: Network Access Control List (ACL)
YANG Data Model";
}
leaf rate-limit {
when "../forwarding = 'ietf-acl:accept'" {
description
"rate-limit valid only when accept action is used";
}
type decimal64 {
fraction-digits 2;
}
description
"rate-limit traffic";
}
}
container statistics {
config false;
description
"Aggregate statistics.";
uses ietf-acl:acl-counters;
}
}
}
}
}
container dots-data {
description
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"Main container for DOTS data channel.";
list dots-client {
key "cuid";
description
"List of DOTS clients.";
leaf cuid {
type string;
description
"A unique identifier that is randomly generated by
a DOTS client to prevent request collisions.";
reference
"RFC YYYY: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification";
}
leaf cdid {
type string;
description
"A client domain identifier conveyed by a
server-domain DOTS gateway to a remote DOTS server.";
reference
"RFC YYYY: Distributed Denial-of-Service Open Threat
Signaling (DOTS) Signal Channel Specification";
}
container aliases {
description
"Set of aliases that are bound to a DOTS client.";
uses aliases;
}
container acls {
description
"Access lists that are bound to a DOTS client.";
uses access-lists;
}
}
container capabilities {
config false;
description
"Match capabilities";
leaf-list address-family {
type enumeration {
enum "ipv4" {
description
"IPv4 is supported.";
}
enum "ipv6" {
description
"IPv6 is supported.";
}
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}
description
"Indicates the IP address families supported by
the DOTS server.";
}
leaf-list forwarding-actions {
type identityref {
base ietf-acl:forwarding-action;
}
description
"Supported forwarding action(s).";
}
leaf rate-limit {
type boolean;
description
"Support of rate-limit action.";
}
leaf-list transport-protocols {
type uint8;
description
"Upper-layer protocol associated with a filtering rule.
Values are taken from the IANA protocol registry:
https://www.iana.org/assignments/protocol-numbers/
protocol-numbers.xhtml
For example, this field contains 1 for ICMP, 6 for TCP
17 for UDP, or 58 for ICMPv6.";
}
container ipv4 {
description
"Indicates IPv4 header fields that are supported to enforce
ACLs.";
leaf dscp {
type boolean;
description
"Support of filtering based on DSCP.";
}
leaf ecn {
type boolean;
description
"Support of filtering based on ECN.";
}
leaf length {
type boolean;
description
"Support of filtering based on the Total Length.";
}
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leaf ttl {
type boolean;
description
"Support of filtering based on the TTL.";
}
leaf protocol {
type boolean;
description
"Support of filtering based on protocol field.";
}
leaf ihl {
type boolean;
description
"Support of filtering based on the Internet Header
Length (IHL).";
}
leaf flags {
type boolean;
description
"Support of filtering based on the 'flags'";
}
leaf offset {
type boolean;
description
"Support of filtering based on the 'offset'.";
}
leaf identification {
type boolean;
description
"Support of filtering based on the 'identification'.";
}
leaf source-prefix {
type boolean;
description
"Support of filtering based on the source prefix.";
}
leaf destination-prefix {
type boolean;
description
"Support of filtering based on the destination prefix.";
}
leaf fragment {
type boolean;
description
"Indicates the capability of a DOTS server to
enforce filters on IPv4 fragments. That is 'fragment'
clause is supported.";
}
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}
container ipv6 {
description
"Indicates IPv6 header fields that are supported to enforce
ACLs.";
leaf dscp {
type boolean;
description
"Support of filtering based on DSCP.";
}
leaf ecn {
type boolean;
description
"Support of filtering based on ECN.";
}
leaf flow-label {
type boolean;
description
"Support of filtering based on the Flow label.";
}
leaf length {
type boolean;
description
"Support of filtering based on the Payload Length.";
}
leaf protocol {
type boolean;
description
"Support of filtering based on the Next Header field.";
}
leaf hoplimit {
type boolean;
description
"Support of filtering based on the Hop Limit.";
}
leaf source-prefix {
type boolean;
description
"Support of filtering based on the source prefix.";
}
leaf destination-prefix {
type boolean;
description
"Support of filtering based on the destination prefix.";
}
leaf fragment {
type boolean;
description
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"Indicates the capability of a DOTS server to
enforce filters on IPv6 fragments.";
}
}
container tcp {
description
"Set of TCP fields that are supported by the DOTS server
to enfoce filters.";
leaf sequence-number {
type boolean;
description
"Support of filtering based on the TCP sequence number.";
}
leaf acknowledgement-number {
type boolean;
description
"Support of filtering based on the TCP acknowledgement
number.";
}
leaf data-offset {
type boolean;
description
"Support of filtering based on the TCP data-offset.";
}
leaf reserved {
type boolean;
description
"Support of filtering based on the TCP reserved field.";
}
leaf flags {
type boolean;
description
"Support of filtering, as defined in RFC ZZZZ, based
on the TCP flags.";
}
leaf flags-bitmask {
type boolean;
description
"Support of filtering based on the TCP flags bitmask.";
}
leaf window-size {
type boolean;
description
"Support of filtering based on the TCP window size.";
}
leaf urgent-pointer {
type boolean;
description
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"Support of filtering based on the TCP urgent pointer.";
}
leaf options {
type boolean;
description
"Support of filtering based on the TCP options.";
}
leaf source-port {
type boolean;
description
"Support of filtering based on the source port number.";
}
leaf destination-port {
type boolean;
description
"Support of filtering based on the destination port
number.";
}
leaf port-range {
type boolean;
description
"Support of filtering based on a port range.";
}
}
container udp {
description
"Set of UDP fields that are supported by the DOTS server
to enforce filters.";
leaf length {
type boolean;
description
"Support of filtering based on the UDP length.";
}
leaf source-port {
type boolean;
description
"Support of filtering based on the source port number.";
}
leaf destination-port {
type boolean;
description
"Support of filtering based on the destination port
number.";
}
leaf port-range {
type boolean;
description
"Support of filtering based on a port range.";
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}
}
container icmp {
description
"Set of ICMP/ICMPv6 fields that are supported by the DOTS
server to enforce filters.";
leaf type {
type boolean;
description
"Support of filtering based on the ICMP/ICMPv6 type.";
}
leaf code {
type boolean;
description
"Support of filtering based on the ICMP/ICMPv6 code.";
}
leaf rest-of-header {
type boolean;
description
"Support of filtering based on the ICMP four-bytes
field.";
}
}
}
}
}
<CODE ENDS>
5. Managing DOTS Clients
5.1. Registering DOTS Clients
In order to make use of DOTS data channel, a DOTS client MUST
register to its DOTS server(s) by creating a DOTS client ('dots-
client') resource. To that aim, DOTS clients SHOULD send a POST
request (shown in Figure 11).
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POST /restconf/data/ietf-dots-data-channel:dots-data HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "string"
}
]
}
Figure 11: POST to Register
The 'cuid' (client unique identifier) parameter is described below:
cuid: A globally unique identifier that is meant to prevent
collisions among DOTS clients. This attribute has the same
meaning, syntax, and processing rules as the 'cuid' attribute
defined in [I-D.ietf-dots-signal-channel].
DOTS clients MUST use the same 'cuid' for both signal and data
channels.
This is a mandatory attribute.
In deployments where server-domain DOTS gateways are enabled,
identity information about the origin source client domain SHOULD be
supplied to the DOTS server. That information is meant to assist the
DOTS server to enforce some policies. These policies can be enforced
per-client, per-client domain, or both. Figure 12 shows an example
of a request relayed by a server-domain DOTS gateway.
POST /restconf/data/ietf-dots-data-channel:dots-data HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "string",
"cdid": "string"
}
]
}
Figure 12: POST to Register (via a Server-Domain DOTS Gateway)
A server-domain DOTS gateway SHOULD add the following attribute:
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cdid: This attribute has the same meaning, syntax, and processing
rules as the 'cdid' attribute defined in
[I-D.ietf-dots-signal-channel].
In deployments where server-domain DOTS gateways are enabled,
'cdid' does not need to be inserted when relaying DOTS methods to
manage aliases (Section 6) or filtering rules (Section 7). DOTS
servers are responsible for maintaining the association between
'cdid' and 'cuid' for policy enforcement purposes.
This is an optional attribute.
A request example to create a 'dots-client' resource is depicted in
Figure 13. This request is relayed by a server-domain DOTS gateway
as hinted by the presence of the 'cdid' attribute.
POST /restconf/data/ietf-dots-data-channel:dots-data HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "dz6pHjaADkaFTbjr0JGBpw",
"cdid": "7eeaf349529eb55ed50113"
}
]
}
Figure 13: POST to Register (DOTS gateway)
DOTS servers MUST limit the number of 'dots-client' resources to be
created by the same DOTS client to 1 per request. Requests with
multiple 'dots-client' resources MUST be rejected by DOTS servers.
To that aim, the DOTS server MUST rely on the same procedure to
unambiguously identify a DOTS client as discussed in Section 4.4.1 of
[I-D.ietf-dots-signal-channel].
The DOTS server indicates the result of processing the POST request
using status-line codes. Status codes in the range "2xx" codes are
success, "4xx" codes are some sort of invalid requests and "5xx"
codes are returned if the DOTS server has erred or is incapable of
accepting the creation of the 'dots-client' resource. In particular,
o "201 Created" status-line is returned in the response, if the DOTS
server has accepted the request.
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o "400 Bad Request" status-line is returned by the DOTS server, if
the request does not include a 'cuid' parameter. The error-tag
"missing-attribute" is used in this case.
o "409 Conflict" status-line is returned to the requesting DOTS
client, if the data resource already exists. The error-tag
"resource-denied" is used in this case.
Once a DOTS client registers itself to a DOTS server, it can
create/delete/retrieve aliases (Section 6) and filtering rules
(Section 7).
A DOTS client MAY use the PUT request (Section 4.5 in [RFC8040]) to
register a DOTS client within the DOTS server. An example is shown
in Figure 14.
PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:dots-client": [
{
"cuid": "dz6pHjaADkaFTbjr0JGBpw"
}
]
}
Figure 14: PUT to Register
The DOTS gateway, that inserted a 'cdid' in a PUT request, MUST strip
the 'cdid' parameter in the corresponding response before forwarding
the response to the DOTS client.
5.2. Unregistering DOTS Clients
A DOTS client de-registers from its DOTS server(s) by deleting the
'cuid' resource(s). Resources bound to this DOTS client will be
deleted by the DOTS server. An example of a de-register request is
shown in Figure 15.
DELETE /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: {host}:{port}
Figure 15: De-register a DOTS Client
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6. Managing DOTS Aliases
The following sub-sections define means for a DOTS client to create
aliases (Section 6.1), retrieve one or a list of aliases
(Section 6.2), and delete an alias (Section 6.3).
6.1. Create Aliases
A POST or PUT request is used by a DOTS client to create aliases, for
resources for which a mitigation may be requested. Such aliases may
be used in subsequent DOTS signal channel exchanges to refer more
efficiently to the resources under attack.
DOTS clients within the same domain can create different aliases for
the same resource.
The structure of POST requests used to create aliases is shown in
Figure 16.
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POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:aliases": {
"alias": [
{
"name": "string",
"target-prefix": [
"string"
],
"target-port-range": [
{
"lower-port": integer,
"upper-port": integer
}
],
"target-protocol": [
integer
],
"target-fqdn": [
"string"
],
"target-uri": [
"string"
]
}
]
}
}
Figure 16: POST to Create Aliases
The parameters are described below:
name: Name of the alias.
This is a mandatory attribute.
target-prefix: Prefixes are separated by commas. Prefixes are
represented using Classless Inter-domain Routing (CIDR) notation
[RFC4632]. As a reminder, the prefix length must be less than or
equal to 32 (resp. 128) for IPv4 (resp. IPv6).
The prefix list MUST NOT include broadcast, loopback, or multicast
addresses. These addresses are considered as invalid values. In
addition, the DOTS server MUST validate that these prefixes are
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within the scope of the DOTS client's domain. Other validation
checks may be supported by DOTS servers.
This is an optional attribute.
target-port-range: A range of port numbers.
The port range is defined by two bounds, a lower port number
(lower-port) and an upper port number (upper-port).
When only 'lower-port' is present, it represents a single port
number.
For TCP, UDP, Stream Control Transmission Protocol (SCTP)
[RFC4960], or Datagram Congestion Control Protocol (DCCP)
[RFC4340], the range of port numbers can be, for example,
1024-65535.
This is an optional attribute.
target-protocol: A list of protocols. Values are taken from the
IANA protocol registry [proto_numbers].
The value '0' has a special meaning for 'all protocols'.
This is an optional attribute.
target-fqdn: A list of Fully Qualified Domain Names (FQDNs). An
FQDN is the full name of a resource, rather than just its
hostname. For example, "venera" is a hostname, and
"venera.isi.edu" is an FQDN [RFC1983].
How a name is passed to an underlying name resolution library is
implementation- and deployment-specific. Nevertheless, once the
name is resolved into one or multiple IP addresses, DOTS servers
MUST apply the same validation checks as those for 'target-
prefix'.
This is an optional attribute.
target-uri: A list of Uniform Resource Identifiers (URIs)
[RFC3986].
The same validation checks used for 'target-fqdn' MUST be followed
by DOTS servers to validate a target URI.
This is an optional attribute.
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In POST or PUT requests, at least one of the 'target-prefix',
'target-fqdn', or 'target-uri' attributes MUST be present. DOTS
agents can safely ignore Vendor-Specific parameters they don't
understand.
Figure 17 shows a POST request to create an alias called "https1" for
HTTPS servers with IP addresses 2001:db8:6401::1 and 2001:db8:6401::2
listening on port number 443.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: www.example.com
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:aliases": {
"alias": [
{
"name": "https1",
"target-protocol": [
6
],
"target-prefix": [
"2001:db8:6401::1/128",
"2001:db8:6401::2/128"
],
"target-port-range": [
{
"lower-port": 443
}
]
}
]
}
}
Figure 17: Example of a POST to Create an Alias
"201 Created" status-line MUST be returned in the response if the
DOTS server has accepted the alias.
"409 Conflict" status-line MUST be returned to the requesting DOTS
client, if the request is conflicting with an existing alias name.
The error-tag "resource-denied" is used in this case.
If the request is missing a mandatory attribute or its contains an
invalid or unknown parameter, "400 Bad Request" status-line MUST be
returned by the DOTS server. The error-tag is set to "missing-
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attribute", "invalid-value", or "unknown-element" as a function of
the encountered error.
If the request is received via a server-domain DOTS gateway, but the
DOTS server does not maintain a 'cdid' for this 'cuid' while a 'cdid'
is expected to be supplied, the DOTS server MUST reply with "403
Forbidden" status-line and the error-tag "access-denied". Upon
receipt of this message, the DOTS client MUST register (Section 5).
A DOTS client uses the PUT request to modify the aliases in the DOTS
server. In particular, a DOTS client MUST update its alias entries
upon change of the prefix indicated in the 'target-prefix'.
A DOTS server MUST maintain an alias for at least 10080 minutes (1
week). If no refresh request is seen from the DOTS client, the DOTS
server removes expired entries.
6.2. Retrieve Installed Aliases
GET request is used to retrieve one or all installed aliases by a
DOTS client from a DOTS server (Section 3.3.1 in [RFC8040]). If no
'name' is included in the request, this is an indication that the
request is about retrieving all aliases instantiated by the DOTS
client.
Figure 18 shows an example to retrieve all the aliases that were
instantiated by the requesting DOTS client. The 'content' parameter
and its permitted values are defined in Section 4.8.1 of [RFC8040].
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/aliases?content=all HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 18: GET to Retrieve All Installed Aliases
Figure 19 shows an example of the response message body that includes
all the aliases that are maintained by the DOTS server for the DOTS
client identified by the 'cuid' parameter.
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{
"ietf-dots-data-channel:aliases": {
"alias": [
{
"name": "Server1",
"target-protocol": [
6
],
"target-prefix": [
"2001:db8:6401::1/128",
"2001:db8:6401::2/128"
],
"target-port-range": [
{
"lower-port": 443
}
],
"pending-lifetime": 3596
},
{
"name": "Server2",
"target-protocol": [
6
],
"target-prefix": [
"2001:db8:6401::10/128",
"2001:db8:6401::20/128"
],
"target-port-range": [
{
"lower-port": 80
}
],
"pending-lifetime": 9869
}
]
}
}
Figure 19: An Example of Response Body Listing All Installed Aliases
Figure 20 shows an example of a GET request to retrieve the alias
"Server2" that was instantiated by the DOTS client.
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GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/aliases/alias=Server2?content=all HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 20: GET to Retrieve an Alias
If an alias name ('name') is included in the request, but the DOTS
server does not find that alias name for this DOTS client in its
configuration data, it MUST respond with a "404 Not Found" status-
line.
6.3. Delete Aliases
DELETE request is used to delete an alias maintained by a DOTS
server.
If the DOTS server does not find the alias name, conveyed in the
DELETE request, in its configuration data for this DOTS client, it
MUST respond with a "404 Not Found" status-line.
The DOTS server successfully acknowledges a DOTS client's request to
remove the alias using "204 No Content" status-line in the response.
Figure 21 shows an example of a request to delete an alias.
DELETE /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/aliases/alias=Server1 HTTP/1.1
Host: {host}:{port}
Figure 21: Delete an Alias
7. Managing DOTS Filtering Rules
The following sub-sections define means for a DOTS client to retrieve
DOTS filtering capabilities (Section 7.1), create filtering rules
(Section 7.2), retrieve active filtering rules (Section 7.3), and
delete a filtering rule (Section 7.4).
7.1. Retrieve DOTS Filtering Capabilities
A DOTS client MAY send a GET request to retrieve the filtering
capabilities supported by a DOTS server. Figure 22 shows an example
of such request.
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GET /restconf/data/ietf-dots-data-channel:dots-data\
/capabilities HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 22: GET to Retrieve the Capabilities of a DOTS Server
A DOTS client which issued a GET request to retrieve the filtering
capabilities supported by its DOTS server, SHOULD NOT request for
filtering actions that are not supported by that DOTS server.
Figure 23 shows an example of a response received from a DOTS server
which only supports the mandatory filtering criteria listed in
Section 4.1.
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Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:capabilities": {
"address-family": ["ipv4", "ipv6"],
"forwarding-actions": ["drop", "accept"],
"rate-limit": true,
"transport-protocols": [1, 6, 17, 58],
"ipv4": {
"length": true,
"protocol": true,
"destination-prefix": true,
"source-prefix": true,
"fragment": true
},
"ipv6": {
"length": true,
"protocol": true,
"destination-prefix": true,
"source-prefix": true,
"fragment": true
},
"tcp": {
"flags-bitmask": true,
"source-port": true,
"destination-port": true,
"port-range": true
},
"udp": {
"length": true,
"source-port": true,
"destination-port": true,
"port-range": true
},
"icmp": {
"type": true,
"code": true
}
}
}
Figure 23: Reply to a GET Request with Filtering Capabilities
7.2. Install Filtering Rules
A POST or PUT request is used by a DOTS client to communicate
filtering rules to a DOTS server.
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Figure 24 shows a POST request example to block traffic from
192.0.2.0/24 and destined to 198.51.100.0/24. Other examples are
discussed in Appendix A.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "sample-ipv4-acl",
"type": "ipv4-acl-type",
"activation-type": "activate-when-mitigating",
"aces": {
"ace": [
{
"name": "rule1",
"matches": {
"ipv4": {
"destination-ipv4-network": "198.51.100.0/24",
"source-ipv4-network": "192.0.2.0/24"
}
},
"actions": {
"forwarding": "drop"
}
}
]
}
}
]
}
}
Figure 24: POST to Install Filtering Rules
The meaning of these parameters is as follows:
name: The name of the access list.
This is a mandatory attribute.
type: Indicates the primary intended type of match criteria (e.g.,
IPv4, IPv6). It is set to 'ipv4-acl-type' in the example of
Figure 24.
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This is an optional attribute.
activation-type: Indicates whether an ACL has to be installed
immediately or during mitigation time. If this attribute is not
provided, the DOTS server MUST use 'activate-when-mitigating' as
default value. Filters that are activated only when a mitigation
is in progress MUST be bound to the DOTS client which created the
filtering rule.
This is an optional attribute.
matches: Define criteria used to identify a flow on which to apply
the rule. It can be "l3" (IPv4, IPv6) or "l4" (TCP, UDP, ..).
The detailed match parameters are specified in Section 4.
In the example depicted in Figure 24, an IPv4 matching criteria is
used.
This is an optional attribute.
destination-ipv4-network: The destination IPv4 prefix. DOTS servers
MUST validate that these prefixes are within the scope of the DOTS
client's domain. Other validation checks may be supported by DOTS
servers. If this attribute is not provided, the DOTS server
enforces the ACL on any destination IP address that belong to the
DOTS client's domain.
This is a mandatory attribute in requests with an 'activation-
type' set to 'immediate'.
source-ipv4-network: The source IPv4 prefix.
This is an optional attribute.
actions: Actions in the forwarding ACL category can be "drop" or
"accept". The "accept" action is used to white-list traffic. The
"drop" action is used to black-list traffic.
Accepted traffic may be subject to "rate-limit"; the allowed
traffic rate is represented in bytes per second indicated in IEEE
floating point format [IEEE.754.1985].
This is a mandatory attribute.
The DOTS server indicates the result of processing the POST request
using the status-line header. Concretely, "201 Created" status-line
MUST be returned in the response if the DOTS server has accepted the
filtering rules. If the request is missing a mandatory attribute or
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contains an invalid or unknown parameter (e.g., a match field not
supported by the DOTS server), "400 Bad Request" status-line MUST be
returned by the DOTS server in the response. The error-tag is set to
"missing-attribute", "invalid-value", or "unknown-element" as a
function of the encountered error.
If the request is received via a server-domain DOTS gateway, but the
DOTS server does not maintain a 'cdid' for this 'cuid' while a 'cdid'
is expected to be supplied, the DOTS server MUST reply with "403
Forbidden" status-line and the error-tag "access-denied". Upon
receipt of this message, the DOTS client MUST register (Figure 11).
If the request is conflicting with an existing filtering installed by
another DOTS client of the domain, the DOTS server returns "409
Conflict" status-line to the requesting DOTS client. The error-tag
"resource-denied" is used in this case.
The "insert" query parameter (Section 4.8.5 of [RFC8040]) MAY be used
to specify how an access control entry is inserted within an ACL and
how an ACL is inserted within an ACL set.
The DOTS client uses the PUT request to modify its filtering rules
maintained by the DOTS server. In particular, a DOTS client MUST
update its filtering entries upon change of the destination-prefix.
How such change is detected is out of scope.
A DOTS server MUST maintain a filtering rule for at least 10080
minutes (1 week). If no refresh request is seen from the DOTS
client, the DOTS server removes expired entries. Typically, a
refresh request is a PUT request which echoes the content of a
response to a GET request with all of the read-only parameters
stripped out (e.g. pending-lifetime).
7.3. Retrieve Installed Filtering Rules
A DOTS client periodically queries its DOTS server to check the
counters for installed filtering rules. GET request is used to
retrieve filtering rules from a DOTS server. In order to indicate
which type of data is requested in a GET request, the DOTS client
sets adequately the 'content' parameter.
If the DOTS server does not find the access list name conveyed in the
GET request in its configuration data for this DOTS client, it
responds with a "404 Not Found" status-line.
In order to illustrate the intended behavior, consider the example
depicted in Figure 25. In reference to this example, the DOTS client
requests the creation of an immediate ACL called "test-acl-ipv6-udp".
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PUT /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=test-acl-ipv6-udp HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"type": "ipv6-acl-type",
"activation-type": "immediate",
"aces": {
"ace": [
{
"name": "test-ace-ipv6-udp",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 25: Example of a PUT Request to Create a Filtering
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The peer DOTS server follows the procedure specified in Section 7.2
to process the request. We consider in the following that a positive
response is sent back to the requesting DOTS client to confirm that
the "test-acl-ipv6-udp" ACL is successfully installed by the DOTS
server.
The DOTS client can issue a GET request to retrieve all its filtering
rules and the number of matches for the installed filtering rules as
illustrated in Figure 26. 'content' parameter is set to 'all'. The
message body of the response to this GET request is shown in
Figure 27.
GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw\
/acls?content=all HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 26: Retrieve the Configuration Data and State Data for the
Filtering Rules (GET Request)
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{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"type": "ipv6-acl-type",
"activation-type": "immediate",
"pending-lifetime":9080,
"aces": {
"ace": [
{
"name": "test-ace-ipv6-udp",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 27: Retrieve the Configuration Data and State Data for the
Filtering Rules (Response Message Body)
Also, a DOTS client can issue a GET request to retrieve only
configuration data related to an ACL as shown in Figure 28. It does
so by setting 'content' parameter to 'config'.
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GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=test-acl-ipv6-udp?content=config HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 28: Retrieve the Configuration Data for a Filtering Rule (GET
Request)
A response to this GET request is shown in Figure 29.
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{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"type": "ipv6-acl-type",
"activation-type": "immediate",
"aces": {
"ace": [
{
"name": "test-ace-ipv6-udp",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8:6401::2/127",
"source-ipv6-network": "2001:db8:1234::/96",
"protocol": 17,
"flow-label": 10000
},
"udp": {
"source-port": {
"operator": "lte",
"port": 80
},
"destination-port": {
"operator": "neq",
"port": 1010
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 29: Retrieve the Configuration Data for a Filtering Rule
(Response Message Body)
A DOTS client can also issue a GET request with 'content' parameter
to 'non-config' to exclusively retrieve non-configuration data bound
to a given ACL as shown in Figure 28. A response to this GET request
is shown in Figure 31.
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GET /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=paL8p4Zqo4SLv64TLPXrxA/acls\
/acl=test-acl-ipv6-udp?content=non-config HTTP/1.1
Host: {host}:{port}
Accept: application/yang-data+json
Figure 30: Retrieve the Non-Configuration Data for a Filtering Rule
(GET Request)
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "test-acl-ipv6-udp",
"pending-lifetime": 8000,
"aces": {
"ace": [
{
"name": "test-ace-ipv6-udp"
}
]
}
}
]
}
}
Figure 31: Retrieve the Non-Configuration Data for a Filtering Rule
(Response Message Body)
7.4. Remove Filtering Rules
DELETE request is used by a DOTS client to delete filtering rules
from a DOTS server.
If the DOTS server does not find the access list name carried in the
DELETE request in its configuration data for this DOTS client, it
MUST respond with a "404 Not Found" status-line. The DOTS server
successfully acknowledges a DOTS client's request to withdraw the
filtering rules using "204 No Content" status-line, and removes the
filtering rules accordingly.
Figure 32 shows an example of a request to remove the IPv4 ACL
"sample-ipv4-acl" created in Section 7.2.
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DELETE /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw/acls\
/acl=sample-ipv4-acl HTTP/1.1
Host: {host}:{port}
Figure 32: Remove a Filtering Rule (DELETE Request)
Figure 33 shows an example of a response received from the DOTS
server to confirm the deletion of "sample-ipv4-acl".
HTTP/1.1 204 No Content
Server: Apache
Date: Fri, 27 Jul 2018 10:05:15 GMT
Cache-Control: no-cache
Content-Type: application/yang-data+json
Content-Length: 0
Connection: Keep-Alive
Figure 33: Remove a Filtering Rule (Response)
8. Operational Considerations
The following operational considerations should be taken into
account:
o DOTS server MUST NOT enable both DOTS data channel and direct
configuration to avoid race conditions and inconsistent
configurations arising from simultaneous updates from multiple
sources.
o DOTS agents SHOULD enable DOTS data channel to configure aliases
and ACLs, and only use direct configuration as a stop-gap
mechanism to test DOTS signal channel with aliases and ACLs.
Further, direct configuration SHOULD only be used when the on-path
DOTS agents are within the same domain.
o If the DOTS server has enabled direct configuration, it can reject
the DOTS data channel connection using hard ICMP error [RFC1122]
or RST (Reset) bit in the TCP header or reject the RESTCONF
request using an error response containing a "503 Service
Unavailable" status-line.
9. IANA Considerations
This document requests IANA to register the following URI in the
"IETF XML Registry" [RFC3688]:
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URI: urn:ietf:params:xml:ns:yang:ietf-dots-data-channel
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" registry [RFC7950].
name: ietf-dots-data-channel
namespace: urn:ietf:params:xml:ns:yang:ietf-dots-data-channel
prefix: data-channel
reference: RFC XXXX
10. Security Considerations
RESTCONF security considerations are discussed in [RFC8040]. In
particular, DOTS agents MUST follow the security recommendations in
Sections 2 and 12 of [RFC8040]. Also, DOTS agents MUST support the
mutual authentication TLS profile discussed in Sections 7.1 and 8 of
[I-D.ietf-dots-signal-channel]. YANG ACL-specific security
considerations are discussed in [I-D.ietf-netmod-acl-model].
Authenticated encryption MUST be used for data confidentiality and
message integrity. The interaction between the DOTS agents requires
Transport Layer Security (TLS) with a cipher suite offering
confidentiality protection and the guidance given in [RFC7525] MUST
be followed to avoid attacks on TLS.
The installation of black-list and white-list rules using RESTCONF
over TLS reveals the attacker IP addresses and legitimate IP
addresses only to the DOTS server trusted by the DOTS client. The
secure communication channel between DOTS agents provides privacy and
prevents a network eavesdropper from gaining access to the black-
listed and white-listed IP addresses.
An attacker may be able to inject RST packets, bogus application
segments, etc., regardless of whether TLS authentication is used.
Because the application data is TLS protected, this will not result
in the application receiving bogus data, but it will constitute a DoS
on the connection. This attack can be countered by using TCP-AO
[RFC5925]. If TCP-AO is used, then any bogus packets injected by an
attacker will be rejected by the TCP-AO integrity check and therefore
will never reach the TLS layer.
In order to prevent leaking internal information outside a client-
domain, client-side DOTS gateways SHOULD NOT reveal the identity of
internal DOTS clients (e.g., source IP address, client's hostname)
unless explicitly configured to do so.
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DOTS servers MUST verify that requesting DOTS clients are entitled to
enforce filtering rules on a given IP prefix. That is, only
filtering rules on IP resources that belong to the DOTS client's
domain MUST be authorized by a DOTS server. The exact mechanism for
the DOTS servers to validate that the target prefixes are within the
scope of the DOTS client's domain is deployment-specific.
Rate-limiting DOTS requests, including those with new 'cuid' values,
from the same DOTS client defends against DoS attacks that would
result in varying the 'cuid' to exhaust DOTS server resources. Rate-
limit policies SHOULD be enforced on DOTS gateways (if deployed) and
DOTS servers.
Applying resources quota per DOTS client and/or per DOTS client
domain (e.g., limit the number of aliases and filters to be install
by DOTS clients) prevents DOTS server resources to be aggressively
used by some DOTS clients and ensures, therefore, DDoS mitigation
usage fairness. Additionally, DOTS servers may limit the number of
DOTS clients that can be enabled per domain.
The presence of DOTS gateways may lead to infinite forwarding loops,
which is undesirable. To prevent and detect such loops, a mechanism
is defined in Section 3.5.
All data nodes defined in the YANG module which can be created,
modified, and deleted (i.e., config true, which is the default) are
considered sensitive. Write operations applied to these data nodes
without proper protection can negatively affect network operations.
Appropriate security measures are recommended to prevent illegitimate
users from invoking DOTS data channel primitives. Nevertheless, an
attacker who can access a DOTS client is technically capable of
launching various attacks, such as:
o Set an arbitrarily low rate-limit, which may prevent legitimate
traffic from being forwarded (rate-limit).
o Set an arbitrarily high rate-limit, which may lead to the
forwarding of illegitimate DDoS traffic (rate-limit).
o Communicate invalid aliases to the server (alias), which will
cause the failure of associating both data and signal channels.
o Set invalid ACL entries, which may prevent legitimate traffic from
being forwarded. Likewise, invalid ACL entries may lead to
forward DDoS traffic.
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11. Contributors
The following individuals have contributed to this document:
o Dan Wing, Email: dwing-ietf@fuggles.com
o Jon Shallow, NCC Group, Email: jon.shallow@nccgroup.com
12. Acknowledgements
Thanks to Christian Jacquenet, Roland Dobbins, Roman Danyliw, Ehud
Doron, Russ White, Gilbert Clark, Kathleen Moriarty, and Nesredien
Suleiman for the discussion and comments.
13. References
13.1. Normative References
[I-D.ietf-dots-signal-channel]
Reddy, 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-25 (work in progress), September
2018.
[I-D.ietf-netmod-acl-model]
Jethanandani, M., Huang, L., Agarwal, S., and D. Blair,
"Network Access Control List (ACL) YANG Data Model",
draft-ietf-netmod-acl-model-19 (work in progress), April
2018.
[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>.
[RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing
(CIDR): The Internet Address Assignment and Aggregation
Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August
2006, <https://www.rfc-editor.org/info/rfc4632>.
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[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7525] Sheffer, Y., Holz, R., and P. Saint-Andre,
"Recommendations for Secure Use of Transport Layer
Security (TLS) and Datagram Transport Layer Security
(DTLS)", BCP 195, RFC 7525, DOI 10.17487/RFC7525, May
2015, <https://www.rfc-editor.org/info/rfc7525>.
[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>.
[RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
<https://www.rfc-editor.org/info/rfc8040>.
13.2. Informative References
[I-D.ietf-dots-architecture]
Mortensen, A., Andreasen, F., K, R.,
christopher_gray3@cable.comcast.com, c., Compton, R., and
N. Teague, "Distributed-Denial-of-Service Open Threat
Signaling (DOTS) Architecture", draft-ietf-dots-
architecture-07 (work in progress), September 2018.
[I-D.ietf-dots-requirements]
Mortensen, A., Moskowitz, R., and R. K, "Distributed
Denial of Service (DDoS) Open Threat Signaling
Requirements", draft-ietf-dots-requirements-15 (work in
progress), August 2018.
[IEEE.754.1985]
Institute of Electrical and Electronics Engineers,
"Standard for Binary Floating-Point Arithmetic", August
1985.
[proto_numbers]
"IANA, "Protocol Numbers"", 2011,
<http://www.iana.org/assignments/protocol-numbers>.
[RFC1122] Braden, R., Ed., "Requirements for Internet Hosts -
Communication Layers", STD 3, RFC 1122,
DOI 10.17487/RFC1122, October 1989,
<https://www.rfc-editor.org/info/rfc1122>.
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[RFC1983] Malkin, G., Ed., "Internet Users' Glossary", FYI 18,
RFC 1983, DOI 10.17487/RFC1983, August 1996,
<https://www.rfc-editor.org/info/rfc1983>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>.
[RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram
Congestion Control Protocol (DCCP)", RFC 4340,
DOI 10.17487/RFC4340, March 2006,
<https://www.rfc-editor.org/info/rfc4340>.
[RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol",
RFC 4960, DOI 10.17487/RFC4960, September 2007,
<https://www.rfc-editor.org/info/rfc4960>.
[RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing,
"Session Traversal Utilities for NAT (STUN)", RFC 5389,
DOI 10.17487/RFC5389, October 2008,
<https://www.rfc-editor.org/info/rfc5389>.
[RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP
Authentication Option", RFC 5925, DOI 10.17487/RFC5925,
June 2010, <https://www.rfc-editor.org/info/rfc5925>.
[RFC6520] Seggelmann, R., Tuexen, M., and M. Williams, "Transport
Layer Security (TLS) and Datagram Transport Layer Security
(DTLS) Heartbeat Extension", RFC 6520,
DOI 10.17487/RFC6520, February 2012,
<https://www.rfc-editor.org/info/rfc6520>.
[RFC6887] Wing, D., Ed., Cheshire, S., Boucadair, M., Penno, R., and
P. Selkirk, "Port Control Protocol (PCP)", RFC 6887,
DOI 10.17487/RFC6887, April 2013,
<https://www.rfc-editor.org/info/rfc6887>.
[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>.
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>.
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[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>.
Appendix A. Sample Examples: Filtering Fragments
This specification strongly recommends the use of "fragment" for
handling fragments.
Figure 34 shows the content of the POST request to be issued by a
DOTS client to its DOTS server to allow the traffic destined to
198.51.100.0/24 and UDP port number 53, but to drop all fragmented
packets. The following ACEs are defined (in this order):
o "drop-all-fragments" ACE: discards all fragments.
o "allow-dns-packets" ACE: accepts DNS packets destined to
198.51.100.0/24.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "dns-fragments",
"type": "ipv4-acl-type",
"aces": {
"ace": [
{
"name": "drop-all-fragments",
"matches": {
"ipv4": {
"fragment": {
"operator": "match",
"type": "isf"
}
}
},
"actions": {
"forwarding": "drop"
}
}
]
"ace": [
{
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"name": "allow-dns-packets",
"matches": {
"ipv4": {
"destination-ipv4-network": "198.51.100.0/24"
}
"udp": {
"destination-port": {
"operator": "eq",
"port": 53
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 34: Filtering IPv4 Fragmented Packets (Recommended)
Figure 35 shows a POST request example issued by a DOTS client to its
DOTS server to allow the traffic destined to 2001:db8::/32 and UDP
port number 53, but to drop all fragmented packets. The following
ACEs are defined (in this order):
o "drop-all-fragments" ACE: discards all fragments (including atomic
fragments). That is, IPv6 packets which include a Fragment header
(44) are dropped.
o "allow-dns-packets" ACE: accepts DNS packets destined to
2001:db8::/32.
POST /restconf/data/ietf-dots-data-channel:dots-data\
/dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
Host: {host}:{port}
Content-Type: application/yang-data+json
{
"ietf-dots-data-channel:acls": {
"acl": [
{
"name": "dns-fragments",
"type": "ipv6-acl-type",
"aces": {
"ace": [
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{
"name": "drop-all-fragments",
"matches": {
"ipv6": {
"fragment": {
"operator": "match",
"type": "isf"
}
}
},
"actions": {
"forwarding": "drop"
}
}
]
"ace": [
{
"name": "allow-dns-packets",
"matches": {
"ipv6": {
"destination-ipv6-network": "2001:db8::/32"
}
"udp": {
"destination-port": {
"operator": "eq",
"port": 53
}
}
},
"actions": {
"forwarding": "accept"
}
}
]
}
}
]
}
}
Figure 35: Filtering IPv6 Fragmented Packets
Authors' Addresses
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Mohamed Boucadair (editor)
Orange
Rennes 35000
France
Email: mohamed.boucadair@orange.com
Tirumaleswar Reddy (editor)
McAfee, Inc.
Embassy Golf Link Business Park
Bangalore, Karnataka 560071
India
Email: kondtir@gmail.com
Kaname Nishizuka
NTT Communications
GranPark 16F 3-4-1 Shibaura, Minato-ku
Tokyo 108-8118
Japan
Email: kaname@nttv6.jp
Liang Xia
Huawei
101 Software Avenue, Yuhuatai District
Nanjing, Jiangsu 210012
China
Email: frank.xialiang@huawei.com
Prashanth Patil
Cisco Systems, Inc.
Email: praspati@cisco.com
Andrew Mortensen
Arbor Networks, Inc.
2727 S. State St
Ann Arbor, MI 48104
United States
Email: amortensen@arbor.net
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Nik Teague
Verisign, Inc.
United States
Email: nteague@verisign.com
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