Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel
draft-ietf-dots-data-channel-10

Abstract

The document specifies a Distributed Denial-of-Service Open Threat Signaling (DOTS) data channel used for bulk exchange of data not 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:

• "This version of this YANG module is part of RFC XXXX;"
• "RFC XXXX: Distributed Denial-of-Service Open Threat Signaling (DOTS) Data Channel";
• reference: RFC XXXX

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 June 11, 2018.

Copyright Notice

Copyright (c) 2017 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
• 2. Notational Conventions and Terminology
• 3. DOTS Data Channel: Design Overview
• 4. DOTS Server(s) Discovery
• 5. DOTS Data Channel YANG Module
• 5.1. Identifier YANG Tree Structure
• 5.2. Filter YANG Tree Structure
• 5.3. YANG Module
• 6. DOTS Identifiers
• 6.1. Create Identifiers
• 6.2. Retrieve Installed Identifiers
• 6.3. Delete Identifiers
• 7. DOTS Filtering Rules
• 7.1. Install Filtering Rules
• 7.2. Retrieve Installed Filtering Rules
• 7.3. Remove Filtering Rules
• 8. IANA Considerations
• 8.1. DOTS Data Channel JSON Attribute Mappings Registry
• 8.1.1. Registration Template
• 8.1.2. Initial Registry Contents
• 8.2. YANG Module
• 9. Contributors
• 10. Security Considerations
• 11. Acknowledgements
• 12. References
• 12.1. Normative References
• 12.2. Informative References
• Authors' Addresses

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 in this attack can be an application server, a client, a router, a firewall, or an entire network.

     +---------------+                                 +---------------+
     |               | <------- Signal Channel ------> |               |
     |  DOTS Client  |                                 |  DOTS Server  |
     |               | <=======  Data Channel  ======> |               |
     +---------------+                                 +---------------+

Figure 1: DOTS Channels

DDoS Open Threat Signaling (DOTS) [I-D.ietf-dots-architecture] defines two channels: signal and data channels (Figure 1). The DOTS signal channel used to convey that a network is under a DDOS attack to an upstream DOTS server so that appropriate mitigation actions are undertaken on the suspect traffic is further elaborated in [I-D.ietf-dots-signal-channel]. The DOTS data channel is used for infrequent bulk data exchange between DOTS agents in the aim to significantly augment attack response coordination.

Section 2 of [I-D.ietf-dots-architecture] identifies that the DOTS data channel is used to perform the tasks listed below:

• Creating identifiers, such as names or aliases, for resources for which mitigation may be requested:
  1. The DOTS client may submit to the DOTS server a collection of prefixes which it would like to refer to by alias when requesting mitigation. The server can respond to this request with either with a success or failure response (see requirement OP-006 in [I-D.ietf-dots-requirements] and Section 2 in [I-D.ietf-dots-architecture]).

  Refer to

  Section 6.
• Filter management, which enables a DOTS client to request the installation or removal 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:
  1. If a network resource (DOTS client) detects a potential DDoS attack from a set of IP addresses, the DOTS client informs its servicing router (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 ports in the black-list rule. That DOTS gateway in-turn propagates the black-listed IP addresses to the DOTS server which will undertake appropriate action so that traffic from these IP addresses to the target network (specified by the DOTS client) is blocked.
  2. A network has partner sites from which only legitimate traffic arrives and the network wants to ensure that the traffic from these sites is not penalized during DDOS attacks. The DOTS client uses the DOTS data channel to convey the white-listed IP addresses or prefixes of the partner sites to its DOTS server. The DOTS server uses this information to white-list flows from such IP addresses or prefixes reaching the network.

  Refer to

  Section 7.

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 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

The DOTS data channel is intended to be used for bulk data exchanges between DOTS agents. Unlike the signal channel [I-D.ietf-dots-signal-channel], which must operate nominally even when confronted with signal degradation due to packets loss, the data channel is not expected to be constructed to deal with DDoS attack conditions.

As the primary function of the data channel is data exchange, a reliable transport is required in order for DOTS agents to detect data delivery success or failure. RESTCONF [RFC8040] over TLS [RFC5246] over TCP is used for DOTS data channel (Figure 2). RESTCONF uses HTTP methods to provide CRUD (create, read, update, delete) operations on a conceptual datastore containing YANG data, which is compatible with a server implementing NETCONF datastores.

          +--------------+
          |     DOTS     |
          +--------------+
          |   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 models. These basic edit operations allow the DOTS data channel running configuration to be altered by a DOTS client.

DOTS data channel configuration data and state data can be retrieved with the GET method. HTTP status codes are used to report success or failure for RESTCONF operations.

The DOTS client will 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, 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 retrieval of the YANG modules it supports (Section 3.7 in [RFC8040]), for example, a DOTS client may use RESTCONF to retrieve the company proprietary YANG modules supported by the DOTS server.

• Note: This document uses RESTCONF, a protocol based on HTTP [RFC7230], 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 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.

JavaScript Object Notation (JSON) [RFC7159] payload is used to propagate data channel specific payload messages that convey request parameters and response information such as errors. This specification uses the encoding rules defined in [RFC7951] for representing DOTS data channel configuration data defined 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).

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 the DOTS server still has TLS state by returning a TLS message.

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). These 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

This document defines a YANG module (ietf-dots-data-channel) for creating identifiers, such as names or aliases, for resources for which mitigation may be requested. Such identifiers may be used in subsequent DOTS signal channel exchanges to refer more efficiently to the resources under attack. The tree structure for DOTS identifiers is as follows:

    +--rw identifier
       +--rw client-identifier*   binary
       +--rw alias* [alias-name]
          +--rw alias-name           string
          +--rw target-ip*           inet:ip-address
          +--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

[I-D.ietf-dots-signal-channel].

5.2. Filter YANG Tree Structure

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

Examples of ACL management include, but not limited to,:

• Black-list management, which enables a DOTS client to inform the DOTS server about sources from which traffic should be suppressed.
• White-list management, which enables a DOTS client to inform the DOTS server about sources from which traffic should always be accepted.
• Filter management, which enables a DOTS client to request the installation or removal of traffic filters, dropping or rate-limiting unwanted traffic and permitting white-listed traffic.

This document defines the DOTS Data Channel YANG to augment the "ietf-access-control-list" module to support filters based on the client identifier (client-identifier), to support rate-limit action (rate-limit), and to handle fragmented packets (fragments).

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

The tree structure for DOTS filtering rules is as follows:

  augment /ietf-acl:access-lists:
    +--rw client-identifier*   binary
  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* [set-name type]
          +--rw set-name    -> /ietf-acl:access-lists/acl/acl-name
          +--rw type        -> /ietf-acl:access-lists/acl/acl-type

5.3. YANG Module

<CODE BEGINS> file "ietf-dots-data-channel@2017-12-08.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 DOTS Working Group";

  contact
    "Konda, Tirumaleswar Reddy <TirumaleswarReddy_Konda@McAfee.com>
     Mohamed Boucadair <mohamed.boucadair@orange.com>
     Kaname Nishizuka <kaname@nttv6.jp>
     Liang Xia <frank.xialiang@huawei.com>
     Prashanth Patil <praspati@cisco.com>
     Andrew Mortensen <amortensen@arbor.net>
     Nik Teague <nteague@verisign.com>";

  description
    "This module contains YANG definition for configuring
     identifiers 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 2017-12-08 {
    description
      "Initial revision.";
    reference
      "RFC XXXX: Distributed Denial-of-Service Open Threat 
                 Signaling (DOTS) Data Channel";
  }

  container identifier {
    description "Top level container for identifiers";

    leaf-list client-identifier {
      type binary; 
      description  
        "A client identifier conveyed by a
         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 identifiers"; 

      leaf alias-name {
        type string;
        description "alias name";
      }
      
      leaf-list target-ip {
        type inet:ip-address;
        description 
          "IPv4 or IPv6 address identifying the target.";
      }

      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  
                or equal to 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 "client-identifier parameter.";

    leaf-list client-identifier {
      type binary; 
      description  
        "A client identifier conveyed by a DOTS gateway
         to a remote DOTS server.";
    }
  }
    
  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 
      "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 "set-name type";
        ordered-by user;
        description
          "List of ACLs";

        leaf set-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";
        }
      }
    } 
  }
}
 <CODE ENDS>

6. DOTS Identifiers

6.1. Create Identifiers

A POST request is used to create identifiers, such as names or aliases, for resources for which a mitigation may be requested. Such identifiers may then be used in subsequent DOTS signal channel exchanges to refer more efficiently to the resources under attack (Figure 3).

 POST /restconf/data/ietf-dots-data-channel-identifier HTTP/1.1
 Host: {host}:{port}
 Content-Type: "application/yang-data+json"
 {
  "ietf-dots-data-channel:identifier": {
    "client-identifier": [
         "string"
    ],
    "alias": [
      {
        "alias-name": "string",
        "target-ip": [
          "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 identifiers

The header parameters are described below:

client-identifier:

This attribute has the same meaning, syntax and processing rules as the 'client-identifier' attribute defined in [I-D.ietf-dots-signal-channel]. This is an optional attribute.

alias-name:

Name of the alias. This is a mandatory attribute.

target-ip:

IP addresses are separated by commas. This is an optional attribute.

target-prefix:

Prefixes are separated by commas. 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 ports 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 the POST request at least one of the attributes 'target-ip' or 'target-prefix' or 'target-fqdn' or 'target-uri' MUST be present. DOTS agents can safely ignore Vendor-Specific parameters they don't understand.

Figure 4 shows a POST request to create alias called "https1" for HTTP(S) servers with IP addresses 2001:db8:6401::1 and 2001:db8:6401::2 listening on port 443.

POST /restconf/data/ietf-dots-data-channel-identifier HTTP/1.1
Host: www.example.com
Content-Type: "application/yang-data+json"
{
  "ietf-dots-data-channel:identifier": {
    "client-identifier": [
       "dz6pHjaADkaFTbjr0JGBpw",
       "iAYmCNPmrYoKoqzgFMiobw"
    ],
    "alias": [
      {
        "alias-name": "Server1",
        "target-protocol": [
          6
        ],
        "target-ip": [
          "2001:db8:6401::1",
          "2001:db8:6401::2"
        ],
        "target-port-range": [
          {
            "lower-port": 443
          }
        ]
      }
    ]
  }
}

Figure 4: POST to create identifiers

The DOTS server indicates the result of processing the POST request using HTTP response codes. HTTP 2xx codes are success, HTTP 4xx codes are some sort of invalid requests and 5xx codes are returned if the DOTS server has erred or it is incapable of accepting the alias. Response code 201 (Created) will be 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) will be returned in the response. The HTTP response will include the JSON body received in the request.

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

6.2. Retrieve Installed Identifiers

A GET request is used to retrieve the set of installed identifiers from a DOTS server (Section 3.3.1 in [RFC8040]). Figure 5 shows how 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:identifier\
      /client-identifier=dz6pHjaADkaFTbjr0JGBpw,iAYmCNPmrYoKoqzgFMiobw?\
      content=config HTTP/1.1
  Host: {host}:{port}
  Accept: application/yang-data+json

Figure 5: GET to retrieve all the installed identifiers

Figure 6 shows response for all identifiers on the DOTS server.

{
 "ietf-dots-data-channel:identifier": {
    "client-identifier": [
       "dz6pHjaADkaFTbjr0JGBpw",
       "iAYmCNPmrYoKoqzgFMiobw"
    ],
    "alias": [
      {
        "alias-name": "Server1",
        "traffic-protocol": [
          6
        ],
        "target-ip": [
          "2001:db8:6401::1",
          "2001:db8:6401::2"
        ],
        "target-port-range": [
          {
            "lower-port": 443
          }
        ]
      },
      {
        "alias-name": "Server2",
        "target-protocol": [
          6
        ], 
        "target-ip": [
          "2001:db8:6401::10",
          "2001:db8:6401::20"
        ],
        "target-port-range": [
          {
            "lower-port": 80
          }
        ]
      }
    ]
  }
}

Figure 6: Response body

If the DOTS server does not find the alias name conveyed in the GET request in its configuration data, then it responds with a 404 (Not Found) error response code.

6.3. Delete Identifiers

A DELETE request is used to delete identifiers maintained by a DOTS server (Figure 7).

  DELETE /restconf/data/ietf-dots-data-channel:identifier\
         /client-identifier=dz6pHjaADkaFTbjr0JGBpw,\
         iAYmCNPmrYoKoqzgFMiobw/alias-name=Server1 HTTP/1.1
  Host: {host}:{port}

Figure 7: DELETE identifier

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 above 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, then it responds with a 404 (Not Found) error response code. The DOTS server successfully acknowledges a DOTS client's request to remove the identifier using 204 (No Content) in the response.

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, then the DOTS gateway validates if the DOTS client is authorized to signal the filtering rules and if the client is authorized propagates the rules to the DOTS server. Likewise, the DOTS server validates if 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 APIs define means for a DOTS client to configure filtering rules on a DOTS server.

7.1. Install Filtering Rules

A POST request is used to push filtering rules to a DOTS server. Figure 8 shows a POST request example to block traffic from 192.0.2.0/24, destined to 198.51.100.0/24. The ACL JSON configuration for the filtering rule is generated using the ACL YANG data model defined in [I-D.ietf-netmod-acl-model] and the ACL configuration XML for the filtering rule is specified in Section 4.3 of [I-D.ietf-netmod-acl-model].

  POST /restconf/data/ietf-dots-data-channel HTTP/1.1
  Host: www.example.com
  Content-Type: "application/yang-data+json"
  {
   "ietf-dots-data-channel:access-lists": {
      "client-identifier": [
       "dz6pHjaADkaFTbjr0JGBpw",
       "iAYmCNPmrYoKoqzgFMiobw"
      ],
      "acl": [
          { 
               "acl-name": "sample-ipv4-acl",
               "acl-type": "ipv4-acl",
               "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 8: POST to install filterng rules

The header parameters defined in [I-D.ietf-netmod-acl-model] are discussed below:

acl-name:

The name of access-list. This is a mandatory attribute.

acl-type:

Indicates the primary intended type of match criteria (e.g., IPv4, IPv6). This is a mandatory attribute.

protocol:

Internet Protocol numbers. This is an optional 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:

"drop" or "accept" or "rate-limit". "accept" action is used to white-list traffic. "drop" action is used to black-list traffic. "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 an optional attribute.

The DOTS server indicates the result of processing the POST request using HTTP response codes. HTTP 2xx codes are success, HTTP 4xx codes are some sort of invalid requests and 5xx codes are returned if the DOTS server has erred or it is incapable of configuring the filtering rules. Response code 201 (Created) will 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) will be returned in the response.

The "insert" query parameter discussed in Section 4.8.5 of [RFC8040] can be used to specify how a ACE is inserted within an ACL and how a ACL is inserted within an ACL list.

The DOTS client can 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. Figure 9 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-dots-data-channel:access-lists\
      /client-identifier=dz6pHjaADkaFTbjr0JGBpw,iAYmCNPmrYoKoqzgFMiobw?\
      content=all HTTP/1.1
  Host: {host}:{port}
  Accept: application/yang-data+json

Figure 9: GET to retrieve the configuration data and state data for the filtering rules

If the DOTS server does not find the access list name and access list type conveyed in the GET request in its configuration data, then it responds with a 404 (Not Found) error response code.

7.3. Remove Filtering Rules

A DELETE request is used to delete filtering rules from a DOTS server (Figure 10).

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

Figure 10: DELETE to remove the filtering rules

If the DOTS server does not find the access list name and access list type conveyed in the DELETE request in its configuration data, then it responds with a 404 (Not Found) error response code. The DOTS server successfully acknowledges a DOTS client's request to withdraw the filtering rules using 204 (No Content) response code, and removes the filtering rules as soon as possible.

8. IANA Considerations

8.1. DOTS Data Channel JSON Attribute Mappings Registry

The document requests IANA to create a new registry, entitled "DOTS Data Channel JSON Attribute Mappings Registry". The structure of this registry is provided in Section 8.1.1.

The registry is initially populated with the values in Section 8.1.2.

Values from that registry MUST be assigned via Expert Review [RFC8126].

8.1.1. Registration Template

JSON Attribute:

JSON attribute name.

Description:

Brief description of the attribute.

Change Controller:

For Standards Track RFCs, list the "IESG". For others, give the name of the responsible party. Other details (e.g., postal address, email address, home page URI) may also be included.

Specification Document(s):

Reference to the document or documents that specify the parameter, preferably including URIs that can be used to retrieve copies of the documents. An indication of the relevant sections may also be included but is not required.

8.1.2. Initial Registry Contents

• JSON Attribute: "client-identifier"
• Description: Client identifier.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "alias-name"
• Description: Name of alias.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "target-protocol"
• Description: Internet protocol numbers.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "target-port-range"
• Description: The port range, lower-port for lower port number and upper-port for upper port number. For TCP, UDP, SCTP, or DCCP: a range of ports can be, e.g., 80 to 8080.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "lower-port"
• Description: Lower port number for the port range.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "upper-port"
• Description: Upper port number for the port range.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "target-ip"
• Description: IP address.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "target-prefix"
• Description: IP prefix
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "target-fqdn"
• Description: Fully Qualified Domain Name, is the full name of a system, rather than just its hostname. For example, "venera" is a hostname, and "venera.isi.edu" is an FQDN.
• Change Controller: IESG
• Specification Document(s): this document

• JSON Attribute: "target-uri"
• Description: Uniform Resource Identifier (URI).
• Change Controller: IESG
• Specification Document(s): this document

8.2. YANG Module

         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.

         name: ietf-dots-data-channel
         namespace: urn:ietf:params:xml:ns:yang:ietf-dots-data-channel
         prefix: data-channel
         reference: RFC XXXX

This document requests IANA to register the following URI in the "IETF XML Registry" [RFC3688]: [RFC7950].

9. Contributors

The following individuals have contributed to this document:

Dan Wing

Email: dwing-ietf@fuggles.com

10. Security Considerations

Authenticated encryption MUST be used for data confidentiality and message integrity. TLS based on client certificate MUST be used for mutual authentication. 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, DOTS gateways located in the client-domain SHOULD NOT reveal the identity of internal DOTS clients (client-identifier) unless explicitly configured to do so.

Special care should be taken in order to ensure that the activation of the proposed mechanism won't have an impact on the stability of the network (including connectivity and services delivered over that network).

Involved functional elements in the cooperation system must establish exchange instructions and notification over a secure and authenticated channel. Adequate filters can be enforced to avoid that nodes outside a trusted domain can inject request such as deleting filtering rules. Nevertheless, attacks can be initiated from within the trusted domain if an entity has been corrupted. Adequate means to monitor trusted nodes should also be enabled.

RESTCONF security considerations are discussed in [RFC8040].

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 is able to access to a DOTS client can undertake various attacks, such as:

• Set an arbitrarily low rate-limit that may lead to discarding legitimate traffic to be forwarded (rate-limit).
• Set an arbitrarily high rate-limit that may lead to allowing illegitimate DDoS traffic to be forwarded (rate-limit).
• Communicate invalid aliases to the server (alias) that will lead to failure to associate both data and signal channels.
• Set invalid ACL entries that may lead to discard legitimate traffic from being forwarding. 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, and Gilbert Clark for the discussion and comments.

12. References

12.1. Normative References

12.2. Informative References

Authors' Addresses