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DOTS                                                       T. Reddy, Ed.
Internet-Draft                                                    McAfee
Intended status: Standards Track                       M. Boucadair, Ed.
Expires: July 15, 2018                                            Orange
                                                            K. Nishizuka
                                                      NTT Communications
                                                                  L. Xia
                                                                  Huawei
                                                                P. Patil
                                                                   Cisco
                                                            A. Mortensen
                                                    Arbor Networks, Inc.
                                                               N. Teague
                                                          Verisign, Inc.
                                                        January 11, 2018


Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel
                    draft-ietf-dots-data-channel-12

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 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";

   o  reference: RFC XXXX

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.





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   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on July 15, 2018.

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
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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Notational Conventions and Terminology  . . . . . . . . . . .   5
   3.  DOTS Data Channel: Design Overview  . . . . . . . . . . . . .   5
   4.  DOTS Server(s) Discovery  . . . . . . . . . . . . . . . . . .   8
   5.  DOTS Data Channel YANG Module . . . . . . . . . . . . . . . .   8
     5.1.  Identifier YANG Tree Structure  . . . . . . . . . . . . .   8
     5.2.  Filter YANG Tree Structure  . . . . . . . . . . . . . . .   8
       5.2.1.  DOTS ACL YANG Profile . . . . . . . . . . . . . . . .   8
       5.2.2.  DOTS Augmentation to the IETF-ACL YANG Module . . . .  11
     5.3.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .  12
   6.  DOTS Aliases  . . . . . . . . . . . . . . . . . . . . . . . .  19
     6.1.  Create Aliases  . . . . . . . . . . . . . . . . . . . . .  19
     6.2.  Retrieve Installed Aliases  . . . . . . . . . . . . . . .  24
     6.3.  Delete Aliases  . . . . . . . . . . . . . . . . . . . . .  26
   7.  DOTS Filtering Rules  . . . . . . . . . . . . . . . . . . . .  26
     7.1.  Install Filtering Rules . . . . . . . . . . . . . . . . .  27
     7.2.  Retrieve Installed Filtering Rules  . . . . . . . . . . .  29
     7.3.  Remove Filtering Rules  . . . . . . . . . . . . . . . . .  30
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  30



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   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  30
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  31
   11. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  32
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .  32
     12.1.  Normative References . . . . . . . . . . . . . . . . . .  32
     12.2.  Informative References . . . . . . . . . . . . . . . . .  33
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  35

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.

   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)
   [I-D.ietf-dots-architecture] defines an architecture that allows a
   DOTS client to send requests to a DOTS server for DDoS attack
   mitigation.  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




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   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.

      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.








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2.  Notational Conventions and 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-architecture].

   The terminology for describing YANG data modules is defined in
   [RFC7950].  The meaning of the symbols in tree diagrams is defined in
   [I-D.ietf-netmod-yang-tree-diagrams].

   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: Design Overview

   Unlike the DOTS signal channel [I-D.ietf-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 [RFC5246] over TCP as the DOTS data channel
   protocol (Figure 2).

      Note: RESTCONF is a protocol based on HTTP [RFC7230] to provide
      CRUD (create, read, update, delete) operations on a conceptual
      datastore containing YANG data.  Concretely, RESTCONF is used for
      configuring data defined in YANG version 1 [RFC6020] or YANG
      version 1.1 [RFC7950], using the datastore concepts defined in the
      Network Configuration Protocol (NETCONF) [RFC6241].  RESTCONF
      combines the simplicity of the HTTP protocol with the



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      predictability and automation potential of a schema-driven API.
      RESTCONF offers a simple subset of NETCONF functionality and
      provides a simplified interface using REST-like API which
      addresses the needs of the DOTS data channel and hence an optimal
      choice.

                           +-------------------+
                           | DOTS Data Channel |
                           +-------------------+
                           |      RESTCONF     |
                           +-------------------+
                           |        TLS        |
                           +-------------------+
                           |        TCP        |
                           +-------------------+
                           |        IP         |
                           +-------------------+

    Figure 2: Abstract Layering of DOTS Data Channel over RESTCONF over
                                    TLS

   The HTTP POST, PUT, PATCH, and DELETE methods are used to edit data
   resources represented by DOTS data channel YANG data modules.  These
   basic edit operations allow the DOTS data channel running
   configuration to be altered by a DOTS client.

   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 DOTS client performs 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, the 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
   the DOTS server.

   JavaScript Object Notation (JSON) [RFC7159] 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 5) as JSON text.




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   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).

   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 client 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.

   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.

   When a server-domain DOTS gateway is involved in DOTS data channel
   exchanges, the same considerations for manipulating the 'client-
   domain-hash' parameter as specified in [I-D.ietf-dots-signal-channel]
   MUST be followed by DOTS agents.

   A DOTS server may detect conflicting filtering requests from the same
   or distinct DOTS clients which belong to the same domain.  For
   example, a DOTS client would request to blacklist a prefix, while
   another DOTS client would request to whitelist that same 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 7.1
   specifies the behavior when no instruction is supplied to a DOTS
   server.



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4.  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 follow by a DOTS client to place its requests (e.g., contact all
   servers, select one server among the list) when multiple DOTS servers
   are provisioned.

5.  DOTS Data Channel YANG Module

5.1.  Identifier YANG Tree Structure

   The YANG module (ietf-dots-data-channel) allows to create 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
   DOTS aliases is as follows:

       +--rw aliases
          +--rw dots-client* [cuid]
             +--rw cuid                  string
             +--rw client-domain-hash?   string
             +--rw alias* [alias-name]
                +--rw alias-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

   This structure is aligned with [I-D.ietf-dots-signal-channel].

5.2.  Filter YANG Tree Structure

5.2.1.  DOTS ACL YANG Profile

   This document augments the Access Control List (ACL) YANG module
   [I-D.ietf-netmod-acl-model] for managing DOTS filtering rules.  The
   notion of ACL is explained in Section 1 of
   [I-D.ietf-netmod-acl-model].





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   Examples of ACL 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.

   DOTS implementations MUST support the following features defined in
   [I-D.ietf-netmod-acl-model]:

      match-on-ipv4, match-on-ipv6, match-on-tcp, match-on-udp, match-
      on-icmp, ipv4, and ipv6.

   Given that DOTS data channel does not deal with interfaces, the
   support of the "ietf-interfaces" module [RFC7223] and its
   augmentation in the "ietf-access-control-list" module are not
   required for DOTS.  Specifically, the support of interface-related
   features and branches (e.g., interface-attachment, interface-stats,
   acl-aggregate-stats, and interface-acl-aggregate) of the ACL YANG
   module is not required.

   The following forwarding actions MUST be supported:

      'accept' and 'drop'

   The support of 'reject' action is NOT RECOMMENDED 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.  Further, it will be used by an attacker
   as an explicit signal that the traffic is being blocked.

   The following tree structure provides the excerpt of the "ietf-
   access-control-list" module to be supported by DOTS implementations.

    +--rw access-lists
       +--rw acl* [name]
       |  +--rw name        string
       |  +--rw acl-type?   acl-type
       |  +--rw aces
       |     +--rw ace* [rule-name]
       |        +--rw rule-name          string



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       |        +--rw matches
       |        |  +--rw (l3)?
       |        |  |  +--:(ipv4)
       |        |  |  |  +--rw ipv4 {match-on-ipv4}?
       |        |  |  |     +--rw dscp?                       inet:dscp
       |        |  |  |     +--rw ecn?                        uint8
       |        |  |  |     +--rw length?                     uint16
       |        |  |  |     +--rw ttl?                        uint8
       |        |  |  |     +--rw protocol?                   uint8
       |        |  |  |     +--rw source-port-range!
       |        |  |  |     |  +--rw lower-port    inet:port-number
       |        |  |  |     |  +--rw upper-port?   inet:port-number
       |        |  |  |     |  +--rw operation?    operator
       |        |  |  |     +--rw destination-port-range!
       |        |  |  |     |  +--rw lower-port    inet:port-number
       |        |  |  |     |  +--rw upper-port?   inet:port-number
       |        |  |  |     |  +--rw operations?   operator
       |        |  |  |     +--rw ihl?                        uint8
       |        |  |  |     +--rw flags?                      bits
       |        |  |  |     +--rw offset?                     uint16
       |        |  |  |     +--rw identification?             uint16
       |        |  |  |     +--rw destination-ipv4-network?   inet:ipv4-prefix
       |        |  |  |     +--rw source-ipv4-network?        inet:ipv4-prefix
       |        |  |  +--:(ipv6)
       |        |  |     +--rw ipv6 {match-on-ipv6}?
       |        |  |        +--rw dscp?                       inet:dscp
       |        |  |        +--rw ecn?                        uint8
       |        |  |        +--rw length?                     uint16
       |        |  |        +--rw ttl?                        uint8
       |        |  |        +--rw protocol?                   uint8
       |        |  |        +--rw source-port-range!
       |        |  |        |  +--rw lower-port    inet:port-number
       |        |  |        |  +--rw upper-port?   inet:port-number
       |        |  |        |  +--rw operation?    operator
       |        |  |        +--rw destination-port-range!
       |        |  |        |  +--rw lower-port    inet:port-number
       |        |  |        |  +--rw upper-port?   inet:port-number
       |        |  |        |  +--rw operations?   operator
       |        |  |        +--rw next-header?                uint8
       |        |  |        +--rw destination-ipv6-network?   inet:ipv6-prefix
       |        |  |        +--rw source-ipv6-network?        inet:ipv6-prefix
       |        |  |        +--rw flow-label?                 inet:ipv6-flow-label
       |        |  +--rw (l4)?
       |        |  |  +--:(tcp)
       |        |  |  |  +--rw tcp {match-on-tcp}?
       |        |  |  |     +--rw sequence-number?          uint32
       |        |  |  |     +--rw acknowledgement-number?   uint32
       |        |  |  |     +--rw data-offset?              uint8



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       |        |  |  |     +--rw reserved?                 uint8
       |        |  |  |     +--rw flags?                    bits
       |        |  |  |     +--rw window-size?              uint16
       |        |  |  |     +--rw urgent-pointer?           uint16
       |        |  |  |     +--rw options?                  uint32
       |        |  |  +--:(udp)
       |        |  |  |  +--rw udp {match-on-udp}?
       |        |  |  |     +--rw length?   uint16
       |        |  |  +--:(icmp)
       |        |  |     +--rw icmp {match-on-icmp}?
       |        |  |        +--rw type?             uint8
       |        |  |        +--rw code?             uint8
       |        |  |        +--rw rest-of-header?   uint32
       |        +--ro matched-packets?   yang:counter64
       |        +--ro matched-octets?    yang:counter64

5.2.2.  DOTS Augmentation to the IETF-ACL YANG Module

   This document defines the DOTS Data Channel YANG to augment the
   "ietf-access-control-list" module to support filters based on the
   DOTS client unique identifier (cuid) and/or the client domain
   identity (client-domain-hash), to support rate-limit action (rate-
   limit), and to handle fragmented packets (fragments).  The tree
   structure for augmented DOTS filtering rules is as follows:

  augment /ietf-acl:access-lists/ietf-acl:acl:
    +--rw cuid                  string
    +--rw client-domain-hash?   string
    +--rw lifetime              int32
  augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces
          /ietf-acl:ace/ietf-acl:actions:
    +--rw rate-limit?   decimal64
  augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces
          /ietf-acl:ace/ietf-acl:matches/ietf-acl:ipv4-acl:
    +--rw fragments?   empty
  augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces
          /ietf-acl:ace/ietf-acl:matches/ietf-acl:ipv6-acl:
    +--rw fragments?   empty
  augment /ietf-acl:access-lists:
    +--rw dots-acl-order
       +--rw acl-set* [cuid name type]
          +--rw cuid                  -> /ietf-acl:access-lists/acl/cuid
          +--rw client-domain-hash?   -> /ietf-acl:access-lists/acl/client-domain-hash
          +--rw name                  -> /ietf-acl:access-lists/acl/acl-name
          +--rw type                  -> /ietf-acl:access-lists/acl/acl-type

   Filtering fragments adds an additional layer of protection against a
   DoS attack that uses non-initial fragments only.  When there is only



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   Layer 3 information in the ACL entry and the fragments keyword is
   present, for non-initial fragments matching the ACL entry, the 'deny'
   or 'permit' action associated with the ACL entry will be enforced.
   For initial or non-fragment matching the ACL entry, the next ACL
   entry will be processed.  When there is both Layer 3 and Layer 4
   information in the ACL entry and the fragments keyword is present,
   the ACL action is conservative for both permit and deny actions.  The
   actions are conservative to not accidentally deny a fragmented
   portion of a flow because the fragments do not contain sufficient
   information to match all of the filter attributes.  In the deny
   action case, instead of denying a non-initial fragment, the next ACL
   entry is processed.  In the permit case, it is assumed that the Layer
   4 information in the non-initial fragment, if available, matches the
   Layer 4 information in the ACL entry.

5.3.  YANG Module

 <CODE BEGINS> file "ietf-dots-data-channel@2018-01-09.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-inet-types {prefix "inet";}
   import ietf-access-control-list {prefix "ietf-acl";}

   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:  Konda, Tirumaleswar Reddy
               <mailto:TirumaleswarReddy_Konda@McAfee.com>

      Editor:  Mohamed Boucadair
               <mailto:mohamed.boucadair@orange.com>

      Author:  Kaname Nishizuka
               <mailto:kaname@nttv6.jp>

      Author:  Liang Xia
               <mailto:frank.xialiang@huawei.com>

      Author:  Prashanth Patil
               <mailto:praspati@cisco.com>



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      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) 2017 IETF Trust and the persons identified as
      authors of the code.  All rights reserved.

      Redistribution and use in source and binary forms, with or
      without modification, is permitted pursuant to, and subject
      to the license terms contained in, the Simplified BSD License
      set forth in Section 4.c of the IETF Trust's Legal Provisions
      Relating to IETF Documents
      (http://trustee.ietf.org/license-info).

      This version of this YANG module is part of RFC XXXX; see
      the RFC itself for full legal notices.";

   revision 2018-01-09 {
     description
       "Initial revision.";
     reference
       "RFC XXXX: Distributed Denial-of-Service Open Threat
                  Signaling (DOTS) Data Channel";
   }

   container aliases {
     description "Top level container for aliases";

     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
           "I-D.itef-dots-signal-channel: Distributed Denial-of-Service



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                         Open Threat Signaling (DOTS) Signal Channel";
        }

        leaf client-domain-hash {
          type string;
          description
            "A client domain identifier conveyed by a
             server-domain DOTS gateway to a remote DOTS server.";
          reference
            "I-D.itef-dots-signal-channel: Distributed Denial-of-Service
                         Open Threat Signaling (DOTS) Signal Channel";
       }

       list alias {
         key alias-name;
         description
           "List of aliases";

         leaf alias-name {
           type string;
           description "alias name";
         }

         leaf-list target-prefix {
           type inet:ip-prefix;
           description
             "IPv4 or IPv6 prefix identifying the target.";
         }

         list target-port-range {
           key "lower-port upper-port";

           description
             "Port range. When only lower-port is
              present, it represents a single port.";

           leaf lower-port {
             type inet:port-number;
             mandatory true;
             description
               "Lower port number.";
           }

           leaf upper-port {
             type inet:port-number;
             must ". >= ../lower-port" {
                error-message
                  "The upper port number must be greater than



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                   or equal to the lower port number.";
             }
             description
               "Upper port number.";
           }
         }

         leaf-list target-protocol {
           type uint8;
           description
             "Identifies the target protocol number.

              The value '0' means 'all protocols'.

              Values are taken from the IANA protocol registry:
              https://www.iana.org/assignments/protocol-numbers/
              protocol-numbers.xhtml

              For example, 6 for a TCP or 17 for UDP.";
         }

         leaf-list target-fqdn {
           type inet:domain-name;
           description
             "FQDN identifying the target.";
         }

         leaf-list target-uri {
           type inet:uri;
           description
             "URI identifying the target.";
         }
       }
     }
   }

   /*augment "/ietf-acl:access-lists" {
     description
       "Augment ACLs with the identity of the DOTS
        client and client's domain hash.";

     leaf cuid {
       type string;
       description
         "A unique identifier that is randomly
          generated by a DOTS client to prevent
          request collisions.";
       reference



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         "I-D.itef-dots-signal-channel: Distributed Denial-of-Service
                       Open Threat Signaling (DOTS) Signal Channel";
     }

     leaf client-domain-hash {
       type string;
       description
         "A client identifier conveyed by a server-domain DOTS
         gateway to a remote DOTS server.";
     }
   } */

   augment "/ietf-acl:access-lists/ietf-acl:acl" {
     when "derived-from(ietf-acl:acl-type, 'ietf-acl:ipv4-acl')" +
          " or derived-from(ietf-acl:acl-type, 'ietf-acl:ipv6-acl')";

     description
       "Augments ACLs with the identity of the DOTS
        client, the client's domain hash, and the lifetime.";

     leaf cuid {
       type string;
       mandatory true;
       description
         "A unique identifier that is randomly
          generated by a DOTS client to prevent
          request collisions.";
       reference
         "I-D.itef-dots-signal-channel: Distributed Denial-of-Service
                       Open Threat Signaling (DOTS) Signal Channel";
     }

     leaf client-domain-hash {
       type string;
       description
         "A client identifier conveyed by a server-domain DOTS
         gateway to a remote DOTS server.";
     }

     leaf lifetime {
       type int32;
       units "minutes";
       mandatory true;
       description
         "Indicates the lifetime of the filtering rule

          A lifetime of negative one (-1) indicates indefinite
          lifetime for the filtering request.";



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     }
   }

   augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces" +
           "/ietf-acl:ace/ietf-acl:actions" {
     description
       "rate-limit action";
     leaf rate-limit {
       when "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces/" +
            "ietf-acl:ace/ietf-acl:actions/" +
            "ietf-acl:forwarding = 'ietf-acl:accept'" {
       description
         "rate-limit valid only when accept action is used";
       }
       type decimal64 {
         fraction-digits 2;
       }
      description
        "rate-limit traffic";
      }
   }

   augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces" +
           "/ietf-acl:ace/ietf-acl:matches/ietf-acl:ipv4-acl" {
     description
       "Handle non-initial and initial fragments for IPv4 packets.";

     leaf fragments {
       type empty;
       description
         "Handle fragments.";
     }
   }

   augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces" +
           "/ietf-acl:ace/ietf-acl:matches/ietf-acl:ipv6-acl" {
     description
       "Handle non-initial and initial fragments for IPv6 packets.";

     leaf fragments {
       type empty;
       description
         "Handle fragments.";
     }
   }

   augment "/ietf-acl:access-lists" {
     description



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       "Handle ordering of ACLs from a DOTS client";

     container dots-acl-order {
       description
         "Enclosing container for ordering
          the ACLs from a DOTS client";

       list acl-set {
         key "cuid name type";
         ordered-by user;
         description
           "List of ACLs";

         leaf cuid {
           type leafref {
             path "/ietf-acl:access-lists/ietf-acl:acl" +
                  "/cuid";
           }
           description
             "Reference to the CUID";
         }

         leaf client-domain-hash {
           type leafref {
             path "/ietf-acl:access-lists/ietf-acl:acl" +
                  "/client-domain-hash";
           }
           description
             "Reference to the client domain hash.";
         }

         leaf name {
           type leafref {
             path "/ietf-acl:access-lists/ietf-acl:acl" +
                  "/ietf-acl:acl-name";
           }
           description
             "Reference to the ACL set name";
         }

         leaf type {
           type leafref {
             path "/ietf-acl:access-lists/ietf-acl:acl" +
                  "/ietf-acl:acl-type";
           }
           description
             "Reference to the ACL set type";
         }



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       }
     }
   }
 }
  <CODE ENDS>

6.  DOTS Aliases

6.1.  Create Aliases

   A POST request is used 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 (Figure 3).

   DOTS clients within the same domain can create different aliases for
   the same resource.


































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    POST /restconf/data/ietf-dots-data-channel:aliases HTTP/1.1
    Host: {host}:{port}
    Content-Type: application/yang-data+json
    {
     "ietf-dots-data-channel:dots-client": {
       "cuid": string,
       "alias": [
         {
           "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 3: POST to Create Aliases

   The parameters are described below:

   cuid:  A unique identifier that is meant to prevent collisions among
      DOTS clients that belong to the same domain.  This attribute has
      the same meaning, syntax, and processing rules as the 'cuid'
      attribute defined in [I-D.ietf-dots-signal-channel].

      This is a mandatory attribute.

   alias-name:  Name of the alias.

      This is a mandatory attribute.





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   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).

      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.

      This is an optional attribute.

   target-uri:   A list of Uniform Resource Identifiers (URIs)
      [RFC3986].

      This is an optional attribute.

   In deployments where server-domain DOTS gateways are enabled,
   identity information about the origin source client domain has to be
   supplied to the DOTS server.  That information is meant to assist the
   DOTS server to enforce some policies.  Figure 4 shows an example of a
   request relayed by a server-domain DOTS gateway.





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    POST /restconf/data/ietf-dots-data-channel HTTP/1.1
    Host: {host}:{port}
    Content-Type: application/yang-data+json
    {
     "ietf-dots-data-channel:dots-client": {
       "client-domain-hash": "string",
       "cuid": "string",
       "alias": [
         {
           "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 4: POST to Create Aliases (DOTS Gateway)

   A server-domain DOTS gateway may add the following attribute:

   client-domain-hash:  This attribute has the same meaning, syntax, and
      processing rules as the 'client-domain-hash' attribute defined in
      [I-D.ietf-dots-signal-channel].

      This is an optional attribute.

   In the POST request, at least one of the 'target-prefix' or 'target-
   fqdn' or 'target-uri' attributes MUST be present.  DOTS agents can
   safely ignore Vendor-Specific parameters they don't understand.





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   Figure 5 shows a POST request to create 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 HTTP/1.1
   Host: www.example.com
   Content-Type: application/yang-data+json
   {
     "ietf-dots-data-channel:dots-client": {
       "cuid": "7dec-11d0-a765-00a0c91e6bf6@foo.bar.example",
       "alias": [
         {
           "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 5: Example of a POST to Create Aliases

   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 alias.

   "201 Created" status-line is returned in the response if the DOTS
   server has accepted the alias.

   If the request is missing one or more mandatory attributes, or if the
   request contains invalid or unknown parameters, then "400 Bad
   Request" status-line MUST be returned in the response.  The HTTP
   response will include the JSON body received in the request.

   A DOTS client MAY use the PUT request (Section 4.5 in [RFC8040]) to
   create or modify the aliases in the DOTS server.



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6.2.  Retrieve Installed Aliases

   A 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
   'alias-name' parameter is included in the request, this is an
   indication that the request is about retrieving all identifiers
   instantiated by the DOTS client.

   Figure 6 shows an example to retrieve all the identifiers that were
   instantiated by the 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:aliases\
      /cuid=7dec-11d0-a765-00a0c91e6bf6@foo.bar.example?content=config HTTP/1.1
  Host: {host}:{port}
  Accept: application/yang-data+json

              Figure 6: GET to Retrieve All Installed Aliases

   Figure 7 shows an example of 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:dots-client": {
       "cuid": "7dec-11d0-a765-00a0c91e6bf6@foo.bar.example",
       "alias": [
         {
           "alias-name": "Server1",
           "traffic-protocol": [
             6
           ],
           "target-prefix": [
             "2001:db8:6401::1/128",
             "2001:db8:6401::2/128"
           ],
           "target-port-range": [
             {
               "lower-port": 443
             }
           ]
         },
         {
           "alias-name": "Server2",
           "target-protocol": [
             6
           ],
           "target-prefix": [
             "2001:db8:6401::10/128",
             "2001:db8:6401::20/128"
           ],
           "target-port-range": [
             {
               "lower-port": 80
             }
           ]
         }
       ]
     }
   }

                   Figure 7: An Example of Response Body

   If the 'alias-name' parameter is included in the request, but the
   DOTS server does not find that alias name in its configuration data,
   it MUST respond with a "404 Not Found" status-line.








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6.3.  Delete Aliases

   A DELETE request is used to delete aliases maintained by a DOTS
   server.

   In RESTCONF, URI-encoded path expressions are used.  A RESTCONF data
   resource identifier is encoded from left to right, starting with the
   top-level data node, according to the 'api-path' rule defined in
   Section 3.5.3.1 of [RFC8040].  The data node in the path expression
   is a YANG list node and MUST be encoded according to the rules
   defined in Section 3.5.1 of [RFC8040].

   If the DOTS server does not find the alias name conveyed in the
   DELETE request in its configuration data, 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 8 shows an example of a request to delete an alias.

  DELETE /restconf/data/ietf-dots-data-channel:aliases\
         /cuid=7dec-11d0-a765-00a0c91e6bf6@foo.bar.example/alias-name=Server1 HTTP/1.1
  Host: {host}:{port}

                         Figure 8: Delete an Alias

7.  DOTS Filtering Rules

   The DOTS server either receives the filtering rules directly from the
   DOTS client or via a DOTS gateway.

   If the DOTS client signals the filtering rules via a DOTS gateway,
   the DOTS gateway first verifies that the DOTS client is authorized to
   signal the filtering rules.  If the client is authorized, it
   propagates the rules to the DOTS server.  Likewise, the DOTS server
   verifies that the DOTS gateway is authorized to signal the filtering
   rules.  To create or purge filters, the DOTS client sends HTTP
   requests to its DOTS gateway.  The DOTS gateway validates the rules
   in the requests and proxies the requests containing the filtering
   rules to a DOTS server.  When the DOTS gateway receives the
   associated HTTP response from the DOTS server, it propagates the
   response back to the DOTS client.

   The following sub-sections define means for a DOTS client to
   configure filtering rules on a DOTS server.





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7.1.  Install Filtering Rules

   A POST request is used to push filtering rules to a DOTS server.

   Figure 9 shows a POST request example to block traffic from
   192.0.2.0/24 and destined to 198.51.100.0/24.  The ACL JSON
   configuration for the filtering rule is generated using the ACL YANG
   module (Section 4.3 of [I-D.ietf-netmod-acl-model]).

POST /restconf/data/ietf-access-control-list HTTP/1.1
Host: www.example.com
Content-Type: application/yang-data+json
{
  "ietf-access-control-list:access-lists": {
    "acl": [
      {
        "acl-name": "sample-ipv4-acl",
        "acl-type": "ipv4-acl",
        "data-channel:cuid": "7dec-11d0-a765-00a0c91e6bf6@foo.bar.example",
        "data-channel:lifetime": 10080,
        "aces": {
          "ace": [
            {
              "rule-name": "rule1",
              "matches": {
                "ipv4-acl": {
                  "source-ipv4-network": "192.0.2.0/24",
                  "destination-ipv4-network": "198.51.100.0/24"
                }
              },
              "actions": {
                "forwarding": "drop"
              }
            }
          ]
        }
      }
    ]
  }
}

                 Figure 9: POST to Install Filtering Rules

   The meaning of these parameters is as follows:

   acl-name:  The name of the access-list.

      This is a mandatory attribute.



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   acl-type:  Indicates the primary intended type of match criteria
      (e.g., IPv4, IPv6).  It is set to 'ipv4-acl' in this example.

      This is a mandatory attribute.

   cuid:  A unique identifier that is meant to prevent collisions among
      DOTS clients that belong to the same domain
      [I-D.ietf-dots-signal-channel].

      This is a mandatory attribute.

   lifetime:  Lifetime of the ACL, in minutes.  The RECOMMENDED lifetime
      of a ACL is 10080 minutes (1 week).  DOTS clients MUST include
      this parameter in their filtering requests.  Upon the expiry of
      this lifetime, and if the request is not refreshed but no
      mitigation is active, the filtering request is removed.  The
      request can be refreshed by sending the same request again.

      A lifetime of '0' in a request is an invalid value.

      A lifetime of negative one (-1) indicates indefinite lifetime for
      the filtering request.  The DOTS server MAY refuse indefinite
      lifetime, for policy reasons; the granted lifetime value is
      returned in the response.  DOTS clients MUST be prepared to not be
      granted filtering with indefinite lifetimes.

      The DOTS server MUST always indicate the actual lifetime in the
      response and the remaining lifetime in status messages sent to the
      DOTS client.

      This is a mandatory attribute.

   source-ipv4-network:  The source IPv4 prefix.

      This is an optional attribute.

   destination-ipv4-network:  The destination IPv4 prefix.

      This is an optional attribute.

   actions:   Actions in the forwarding ACL category can be "drop" or
      "accept" or "rate-limit".  The "accept" action is used to white-
      list traffic.  The "drop" action is used to black-list traffic.
      The "rate-limit" action is used to rate-limit traffic, the allowed
      traffic rate is represented in bytes per second indicated in IEEE
      floating point format [IEEE.754.1985].

      This is a mandatory attribute.



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   The DOTS server indicates the result of processing the POST request
   using the status-line header. "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 configuring the filtering rules.
   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 one or more mandatory attributes or contains
   invalid or unknown parameters, then "400 Bad Request" status-line
   MUST be returned in the response.

   If the request is conflicting with an existing filtering, the DOTS
   server returns "409 Conflict" status-line to the requesting DOTS
   client.  The error-tag "invalid-value" 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 (ACE) is inserted within an
   ACL and how an ACL is inserted within an ACL set in container dots-
   acl-order.

   The DOTS client MAY use the PUT request to create or modify the
   filtering rules in the DOTS server.

7.2.  Retrieve Installed Filtering Rules

   The DOTS client periodically queries the DOTS server to check the
   counters for installed filtering rules.  A GET request is used to
   retrieve filtering rules from a DOTS server.

   If the DOTS server does not find the access list name and access list
   type conveyed in the GET request in its configuration data, it
   responds with a "404 Not Found" status-line.

   Figure 10 shows how to retrieve all the filtering rules programmed by
   the DOTS client and the number of matches for the installed filtering
   rules.

    GET /restconf/data/ietf-access-control-list:access-lists\
        /data-channel:cuid=7dec-11d0-a765-00a0c91e6bf6@foo.bar.example?\
        content=all HTTP/1.1
    Host: {host}:{port}
    Accept: application/yang-data+json

   Figure 10: GET to Retrieve the Configuration Data and State Data for
                            the Filtering Rules







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7.3.  Remove Filtering Rules

   A DELETE request is used to delete filtering rules from a DOTS
   server.

   If the DOTS server does not find the access list name and access list
   type carried in the DELETE request in its configuration data, it
   responds 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 11 shows an example of a request to remove the IPv4 ACL named
   "sample-ipv4-acl".

  DELETE /restconf/data/ietf-access-control-list:access-lists\
         /data-channel:cuid=7dec-11d0-a765-00a0c91e6bf6@foo.bar.example\
         /acl-name=sample-ipv4-acl\
         /acl-type=ipv4-acl HTTP/1.1
  Host: {host}:{port}

              Figure 11: DELETE to Remove the Filtering Rules

8.  IANA Considerations

   This document requests IANA to register the following URI in the
   "IETF XML Registry" [RFC3688]:

            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

9.  Contributors

   The following individuals have contributed to this document:

   Dan Wing

   Email: dwing-ietf@fuggles.com




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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] and support the mutual authentication
   TLS profile discussed in Sections 7.1 and 8 of
   [I-D.ietf-dots-signal-channel].

   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.

   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.

   Special care should be taken in order to ensure that the activation
   of the proposed mechanism will not affect the stability of the
   network (including connectivity and services delivered over that
   network).

   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).




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   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.

11.  Acknowledgements

   Thanks to Christian Jacquenet, Roland Dobbins, Roman Danyliw, Ehud
   Doron, Russ White, Jon Shallow, Gilbert Clark, and Nesredien Suleiman
   for the discussion and comments.

12.  References

12.1.  Normative References

   [I-D.ietf-dots-architecture]
              Mortensen, A., Andreasen, F., Reddy, T.,
              christopher_gray3@cable.comcast.com, c., Compton, R., and
              N. Teague, "Distributed-Denial-of-Service Open Threat
              Signaling (DOTS) Architecture", draft-ietf-dots-
              architecture-05 (work in progress), October 2017.

   [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", draft-ietf-dots-signal-
              channel-16 (work in progress), January 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-14 (work in progress), October
              2017.

   [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>.







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   [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>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,
              <https://www.rfc-editor.org/info/rfc5246>.

   [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>.

   [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>.

   [RFC8126]  Cotton, M., Leiba, B., and T. Narten, "Guidelines for
              Writing an IANA Considerations Section in RFCs", BCP 26,
              RFC 8126, DOI 10.17487/RFC8126, June 2017,
              <https://www.rfc-editor.org/info/rfc8126>.

12.2.  Informative References

   [I-D.ietf-dots-requirements]
              Mortensen, A., Moskowitz, R., and T. Reddy, "Distributed
              Denial of Service (DDoS) Open Threat Signaling
              Requirements", draft-ietf-dots-requirements-10 (work in
              progress), January 2018.






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   [I-D.ietf-netmod-yang-tree-diagrams]
              Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
              ietf-netmod-yang-tree-diagrams-04 (work in progress),
              December 2017.

   [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>.

   [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>.

   [RFC6020]  Bjorklund, M., Ed., "YANG - A Data Modeling Language for
              the Network Configuration Protocol (NETCONF)", RFC 6020,
              DOI 10.17487/RFC6020, October 2010,
              <https://www.rfc-editor.org/info/rfc6020>.

   [RFC6241]  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
              and A. Bierman, Ed., "Network Configuration Protocol
              (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
              <https://www.rfc-editor.org/info/rfc6241>.

   [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>.



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   [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>.

   [RFC7159]  Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
              Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
              2014, <https://www.rfc-editor.org/info/rfc7159>.

   [RFC7223]  Bjorklund, M., "A YANG Data Model for Interface
              Management", RFC 7223, DOI 10.17487/RFC7223, May 2014,
              <https://www.rfc-editor.org/info/rfc7223>.

   [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>.

Authors' Addresses

   Tirumaleswar Reddy (editor)
   McAfee, Inc.
   Embassy Golf Link Business Park
   Bangalore, Karnataka  560071
   India

   Email: kondtir@gmail.com


   Mohamed Boucadair (editor)
   Orange
   Rennes  35000
   France

   Email: mohamed.boucadair@orange.com


   Kaname Nishizuka
   NTT Communications
   GranPark 16F 3-4-1 Shibaura, Minato-ku
   Tokyo  108-8118
   Japan

   Email: kaname@nttv6.jp








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   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


   Nik Teague
   Verisign, Inc.
   United States

   Email: nteague@verisign.com






















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