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Versions: (draft-reddy-dots-data-channel) 00 01 02 03 04 05 06 07 08 09 10 11 12 13

DOTS                                                       T. Reddy, Ed.
Internet-Draft                                                    McAfee
Intended status: Standards Track                       M. Boucadair, Ed.
Expires: August 2, 2018                                           Orange
                                                            K. Nishizuka
                                                      NTT Communications
                                                                  L. Xia
                                                                  Huawei
                                                                P. Patil
                                                                   Cisco
                                                            A. Mortensen
                                                    Arbor Networks, Inc.
                                                               N. Teague
                                                          Verisign, Inc.
                                                        January 29, 2018


Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel
                             Specification
                    draft-ietf-dots-data-channel-13

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 Specification";

   o  reference: RFC XXXX

   Please update this statement with the RFC number to be assigned to
   the following documents:

   o  "RFC YYYY: Distributed Denial-of-Service Open Threat Signaling
      (DOTS) Signal Channel Specification";



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   o  "RFC ZZZZ: Network Access Control List (ACL) YANG Data Model";

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 August 2, 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
   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.

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.  Tree Structure  . . . . . . . . . . . . . . . . . . . . .   8
     5.2.  YANG Module . . . . . . . . . . . . . . . . . . . . . . .  13
   6.  Registering DOTS Clients  . . . . . . . . . . . . . . . . . .  20
   7.  Managing DOTS Aliases . . . . . . . . . . . . . . . . . . . .  23
     7.1.  Create Aliases  . . . . . . . . . . . . . . . . . . . . .  23
     7.2.  Retrieve Installed Aliases  . . . . . . . . . . . . . . .  28
     7.3.  Delete Aliases  . . . . . . . . . . . . . . . . . . . . .  30



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   8.  Managing DOTS Filtering Rules . . . . . . . . . . . . . . . .  30
     8.1.  Install Filtering Rules . . . . . . . . . . . . . . . . .  30
     8.2.  Retrieve Installed Filtering Rules  . . . . . . . . . . .  33
     8.3.  Remove Filtering Rules  . . . . . . . . . . . . . . . . .  34
   9.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  34
   10. Contributors  . . . . . . . . . . . . . . . . . . . . . . . .  34
   11. Security Considerations . . . . . . . . . . . . . . . . . . .  35
   12. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  36
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  36
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  36
     13.2.  Informative References . . . . . . . . . . . . . . . . .  37
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  39

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)
   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].



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   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 7 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
      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 8 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-requirements].

   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].

   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.

   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, 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.  The abstract layering of DOTS data channel is shown in
   Figure 2.



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                           +-------------------+
                           | 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 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
   "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) [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.

   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).  Mutual
   authentication and coupling of signal and data channels are specified
   in [I-D.ietf-dots-signal-channel].




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   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.

   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 '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
   or per DOTS client domain).

   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.




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   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 8.1
   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.

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.  Tree Structure

   The tree structure for the DOTS data channel YANG module is as
   follows:

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



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          |     +--rw target-fqdn*         inet:domain-name
          |     +--rw target-uri*          inet:uri
          |     +--rw lifetime             int32
          +--rw access-lists
             +--rw acl* [name]
                +--rw name        string
                +--rw type?       ietf-acl:acl-type
                +--rw lifetime    int32
                +--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 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-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



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                      |  |  |     |                inet:port-number
                      |  |  |     +--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
                      |  |  |     +--rw v4-fragments?
                      |  |  |             empty
                      |  |  +--:(ipv6)
                      |  |     +--rw ipv6
                      |  |        +--rw dscp?
                      |  |        |       inet:dscp
                      |  |        +--rw ecn?
                      |  |        |       uint8
                      |  |        +--rw length?
                      |  |        |       uint16
                      |  |        +--rw ttl?
                      |  |        |       uint8
                      |  |        +--rw protocol?
                      |  |        |       uint8
                      |  |        +--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-range-or-operator
                      |  |        |  +--rw (port-range-or-operator)?
                      |  |        |     +--:(range)
                      |  |        |     |  +--rw lower-port
                      |  |        |     |  |       inet:port-number
                      |  |        |     |  +--rw upper-port
                      |  |        |     |          inet:port-number
                      |  |        |     +--:(operator)
                      |  |        |        +--rw operator?



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                      |  |        |        |       operator
                      |  |        |        +--rw port
                      |  |        |                inet:port-number
                      |  |        +--rw destination-ipv6-network?
                      |  |        |       inet:ipv6-prefix
                      |  |        +--rw source-ipv6-network?
                      |  |        |       inet:ipv6-prefix
                      |  |        +--rw flow-label?
                      |  |        |       inet:ipv6-flow-label
                      |  |        +--rw v6-fragments?
                      |  |                empty
                      |  +--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
                      |     +--:(udp)
                      |     |  +--rw udp
                      |     |     +--rw length?   uint16
                      |     +--:(icmp)
                      |        +--rw icmp
                      |           +--rw type?             uint8
                      |           +--rw code?             uint8
                      |           +--rw rest-of-header?   uint32
                      +--rw actions
                      |  +--rw forwarding    identityref
                      |  +--rw rate-limit?   decimal64
                      +--ro statistics
                         +--ro matched-packets?   yang:counter64
                         +--ro matched-octets?    yang:counter64

   The DOTS data channel YANG module (ietf-dots-data-channel) allows to
   manage aliases for resources for which mitigation may be requested.




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   Such aliases may be used in subsequent DOTS signal channel exchanges
   to refer more efficiently to the resources under attack.

   Also, the module allows managing 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.

   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.

   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.

   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.  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.

   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
   supported in 'ietf-dots-data-channel' because it is not appropriate
   in the context of DDoS mitigation.  Generating ICMP messages to



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   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.

   Filtering rules instructed by a DOTS client assumes a default
   direction: the destination is the DOTS client domain.

   This document supports fragment filtering which adds an additional
   layer of protection against a DoS attack that uses non-initial
   fragments only.  When there is only layer 3 information in the ACL
   entry and the fragments keyword is present, for non-initial fragments
   matching the ACE entry, the 'deny' or 'accept' action associated with
   the ACE entry will be enforced.  For initial or non-fragment matching
   the ACE entry, the next ACE entry will be processed.  When there is
   both layer 3 and layer 4 information in the ACE entry and the
   fragments keyword is present, the ACE action is conservative for both
   'accept' 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 ACE entry is processed.  In the
   'accept' case, it is assumed that the layer 4 information in the non-
   initial fragment, if available, matches the layer 4 information in
   the ACE entry.

   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.

   In order to avoid stale entries, a lifetime is associated with alias
   and filtering entries.  DOTS clients include a suggested lifetime in
   the request, but it is up to the DOTS server to decide whether it
   honors that hint or it has to proceed as per its local policies.

5.2.  YANG Module

  <CODE BEGINS> file "ietf-dots-data-channel@2018-01-22.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;
    }



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    import ietf-packet-fields {
      prefix packet-fields;
    }
    import ietf-dots-signal-channel {
      prefix dots-signal;
    }

    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>

       Author:  Andrew Mortensen
                <mailto:amortensen@arbor.net>

       Author:  Nik Teague
                <mailto:nteague@verisign.com>

       Author:  Jon Shallow
                <mailto:jon.shallow@nccgroup.trust>";
    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
       set forth in Section 4.c of the IETF Trust's Legal Provisions



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       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 2018-01-22 {
      description
        "Initial revision.";
      reference
        "RFC XXXX: Distributed Denial-of-Service Open Threat
                   Signaling (DOTS) Data Channel Specification";
    }

    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 lifetime {
          type int32;
          units "minutes";
          mandatory true;
          description
            "Indicates the lifetime of the alias entry.

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

    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



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           Access List 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 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 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.";
        }
        container aces {
          description
            "The access-list-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).";



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              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";

              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;
                  leaf v4-fragments {
                    type empty;
                    description
                      "Handle IPv4 fragments.";
                  }
                  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;
                  leaf v6-fragments {
                    type empty;
                    description
                      "Handle IPv6 fragments.";
                  }
                  description
                    "Rule set that matches IPv6 header.";
                }
                description
                  "Either IPv4 or IPv6.";
              }



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              choice l4 {
                container tcp {
                  uses packet-fields:acl-tcp-header-fields;
                  description
                    "Rule set that matches TCP header.";
                }
                container udp {
                  uses packet-fields:acl-udp-header-fields;
                  description
                    "Rule set that matches UDP header.";
                }
                container icmp {
                  uses packet-fields:acl-icmp-header-fields;
                  description
                    "Rule set that matches ICMP header.";
                }
                description
                  "Can be TCP, UDP, or ICMP";
              }
            }
            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;



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              description
                "Aggregate statistics.";
              uses ietf-acl:acl-counters;
            }
          }
        }
      }
    }

    container dots-data {
      description
        "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 access-lists {
          description
            "Access lists that are bound to a DOTS client.";
           uses access-lists;
        }
      }
    }
  }
   <CODE ENDS>



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6.  Registering DOTS Clients

   In order to create a new DOTS client ('dots-client') resource on DOTS
   servers, DOTS clients MUST send a POST request (shown in Figure 3).

    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 3: 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 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: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 4: POST to Register (DOTS Gateway)

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

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

      The DOTS gateway that inserted a 'cdid' in a request, MUST strip
      the 'cdid' parameter in the corresponding response before
      forwarding the response to the DOTS client.

      This is an optional attribute.

   A request example to create a 'dots-client' resource is depicted in
   Figure 5.  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 5: 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



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   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.

   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 7) and filtering rules
   (Section 8).

   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 6.

    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 6: PUT to Register

   A DOTS client may de-register from its DOTS server by deleting the
   'cuid' resource.  An example is shown in Figure 7.







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    DELETE /restconf/data/ietf-dots-data-channel:dots-data\
           /dots-client=dz6pHjaADkaFTbjr0JGBpw HTTP/1.1
    Host: {host}:{port}

                    Figure 7: De-register a DOTS Client

7.  Managing DOTS Aliases

   The following sub-sections define means for a DOTS client to create
   aliases (Section 7.1), retrieve one or a list of aliases
   (Section 7.2), and delete an alias (Section 7.3).

7.1.  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 8.



























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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"
           ],
           "lifetime": integer
         }
       ]
     }
   }

                     Figure 8: 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



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      addition, the DOTS server MUST validate that these prefixes are
      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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   lifetime:  Lifetime of the alias, in minutes.  The RECOMMENDED
      lifetime of an alias is 10080 minutes (1 week).  DOTS clients MUST
      include this parameter in their alias creation requests.  Upon the
      expiry of this lifetime, and if the request is not refreshed but
      no mitigation is active, the alias entry 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 alias.  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 aliases
      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.

   In POST 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 9 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.






















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   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
             }
           ],
           "lifetime": 10080
         }
       ]
     }
   }

              Figure 9: 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-
   attribute", "invalid-value", or "unknown-element" as a function of
   the encountered error.

   A DOTS client MAY use the PUT request to modify the aliases in the
   DOTS server.







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7.2.  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 10 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=config HTTP/1.1
     Host: {host}:{port}
     Accept: application/yang-data+json

             Figure 10: GET to Retrieve All Installed Aliases

   Figure 11 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",
           "traffic-protocol": [
             6
           ],
           "target-prefix": [
             "2001:db8:6401::1/128",
             "2001:db8:6401::2/128"
           ],
           "target-port-range": [
             {
               "lower-port": 443
             }
           ],
           "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
             }
           ],
           "lifetime": 9869
         }
       ]
     }
   }

                  Figure 11: An Example of Response Body

   Figure 12 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=config HTTP/1.1
     Host: {host}:{port}
     Accept: application/yang-data+json

                    Figure 12: 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.

7.3.  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 13 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 13: Delete an Alias

8.  Managing DOTS Filtering Rules

   The following sub-sections define means for a DOTS client to create
   filtering rules (Section 8.1), retrieve active filtering rules
   (Section 8.2), and delete a filtering rule (Section 8.3).

8.1.  Install Filtering Rules

   A POST or PUT request is used by a DOTS client to communicate
   filtering rules to a DOTS server.

   Figure 14 shows a POST request example to block traffic from
   192.0.2.0/24 and destined to 198.51.100.0/24.




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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:access-lists": {
       "acl": [
         {
           "name": "sample-ipv4-acl",
           "type": "ipv4-acl-type",
           "lifetime": 10080,
           "aces": {
             "ace": [
               {
                 "name": "rule1",
                 "matches": {
                   "l3": {
                     "ipv4" {
                        "destination-ipv4-network": "198.51.100.0/24"
                        "source-ipv4-network": "192.0.2.0/24",
                     }
                   }
                 },
                 "actions": {
                   "forwarding": "drop"
                 }
               }
             ]
           }
         }
       ]
     }
   }

                Figure 14: 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 this example.

      This is an optional attribute.





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   lifetime:  Lifetime of the ACL, in minutes.  It MUST follow the same
      rules specified in Section 7.1 for alias lifetime, but applied to
      an ACL.

      This is a mandatory 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 5.

      In this example, 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 an optional attribute.

   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
   contains an invalid or unknown parameter, "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 conflicting with an existing filtering installed by
   another DOTS client of the domain, the DOTS server returns "409



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   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 MAY use the PUT request to modify its filtering rules
   maintained by the DOTS server.

8.2.  Retrieve Installed Filtering Rules

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

   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.

   Figure 15 shows how to retrieve all the filtering rules that were
   instantiated by the DOTS client and the number of matches for the
   installed filtering rules.

     GET /restconf/data/ietf-dots-data-channel:dots-data\
         /dots-client=dz6pHjaADkaFTbjr0JGBpw\
         /access-lists?content=all HTTP/1.1
     Host: {host}:{port}
     Accept: application/yang-data+json

   Figure 15: GET to Retrieve the Configuration Data and State Data for
                            the Filtering Rules

   Figure 16 shows how to retrieve "sample-ipv6-acl" filtering rule
   instantiated by the DOTS client, having
   "cuid=dz6pHjaADkaFTbjr0JGBpw", and the number of matches for the
   installed filtering rules.

     GET /restconf/data/ietf-dots-data-channel:dots-data\
         /dots-client=dz6pHjaADkaFTbjr0JGBpw/access-lists\
         /acl=sample-ipv6-acl?content=all HTTP/1.1
     Host: {host}:{port}
     Accept: application/yang-data+json

   Figure 16: GET to Retrieve the Configuration Data and State Data for
                             a Filtering Rule





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8.3.  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 17 shows an example of a request to remove the IPv4 ACL named
   "sample-ipv4-acl".

     DELETE  /restconf/data/ietf-dots-data-channel:dots-data\
             /dots-client=dz6pHjaADkaFTbjr0JGBpw/access-lists\
             /acl=sample-ipv4-acl HTTP/1.1
     Host: {host}:{port}

               Figure 17: DELETE to Remove a Filtering Rule

9.  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

10.  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.trust





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11.  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.

   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.

   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.

   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.





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   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.

12.  Acknowledgements

   Thanks to Christian Jacquenet, Roland Dobbins, Roman Danyliw, Ehud
   Doron, Russ White, Gilbert Clark, 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-17 (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-15 (work in progress), January
              2018.







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   [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>.

   [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>.

   [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., 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-requirements]
              Mortensen, A., Moskowitz, R., and T. Reddy, "Distributed
              Denial of Service (DDoS) Open Threat Signaling
              Requirements", draft-ietf-dots-requirements-12 (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>.

   [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>.





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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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