Network Access Control List (ACL) YANG Data Model
draft-ietf-netmod-acl-model-14

NETMOD WG                                                M. Jethanandani
Internet-Draft                                        Cisco Systems, Inc
Intended status: Standards Track                                L. Huang
Expires: March 16, 2018                                 General Electric
                                                              S. Agarwal
                                                     Cisco Systems, Inc.
                                                                D. Blair
                                                      Cisco Systems, INc
                                                      September 12, 2017


           Network Access Control List (ACL) YANG Data Model
                     draft-ietf-netmod-acl-model-13

Abstract

   This document describes a data model of Access Control List (ACL)
   basic building blocks.

   Editorial Note (To be removed by RFC Editor)

   This draft contains many placeholder values that need to be replaced
   with finalized values at the time of publication.  This note
   summarizes all of the substitutions that are needed.  Please note
   that no other RFC Editor instructions are specified anywhere else in
   this document.

   Artwork in this document contains shorthand references to drafts in
   progress.  Please apply the following replacements

   o  "XXXX" --> the assigned RFC value for this draft both in this
      draft and in the YANG models under the revision statement.

   o  Revision date in model needs to get updated with the date the
      draft gets approved.  The date also needs to get reflected on the
      line with <CODE BEGINS>.

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 http://datatracker.ietf.org/drafts/current/.





Jethanandani, et al.     Expires March 16, 2018                 [Page 1]


Internet-Draft               ACL YANG model               September 2017


   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 March 16, 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
   (http://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
     1.1.  Definitions and Acronyms  . . . . . . . . . . . . . . . .   3
   2.  Problem Statement . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Understanding ACL's Filters and Actions . . . . . . . . . . .   4
     3.1.  ACL Modules . . . . . . . . . . . . . . . . . . . . . . .   5
   4.  ACL YANG Models . . . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  IETF Access Control List module . . . . . . . . . . . . .   9
     4.2.  IETF Packet Fields module . . . . . . . . . . . . . . . .  18
     4.3.  An ACL Example  . . . . . . . . . . . . . . . . . . . . .  31
     4.4.  Port Range Usage Example  . . . . . . . . . . . . . . . .  32
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  33
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  34
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  34
   8.  Open Issues . . . . . . . . . . . . . . . . . . . . . . . . .  35
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  35
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .  35
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  36
   Appendix A.  Extending ACL model examples . . . . . . . . . . . .  36
     A.1.  Example of extending existing model for route filtering .  36
     A.2.  A company proprietary module example  . . . . . . . . . .  38
     A.3.  Linux nftables  . . . . . . . . . . . . . . . . . . . . .  44
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  45





Jethanandani, et al.     Expires March 16, 2018                 [Page 2]


Internet-Draft               ACL YANG model               September 2017


1.  Introduction

   Access Control List (ACL) is one of the basic elements used to
   configure device forwarding behavior.  It is used in many networking
   technologies such as Policy Based Routing, Firewalls etc.

   An ACL is an ordered set of rules that is used to filter traffic on a
   networking device.  Each rule is represented by an Access Control
   Entry (ACE).

   Each ACE has a group of match criteria and a group of action
   criteria.

   The match criteria consist of a tuple of packet header match criteria
   and can have metadata match criteria as well.

   o  Packet header matches apply to fields visible in the packet such
      as address or class of service or port numbers.

   o  In case vendor supports it, metadata matches apply to fields
      associated with the packet but not in the packet header such as
      input interface or overall packet length

   The actions specify what to do with the packet when the matching
   criteria is met.  These actions are any operations that would apply
   to the packet, such as counting, policing, or simply forwarding.The
   list of potential actions is endless depending on the capabilities of
   the networked devices.

   Access Control List is also widely knowns as ACL (pronounce as [ak-uh
   l]) or Access List.  In this document, Access Control List, ACL and
   Access List are used interchangeably.

   The matching of filters and actions in an ACE/ACL are triggered only
   after application/attachment of the ACL to an interface, VRF, vty/tty
   session, QoS policy, routing protocols amongst various other config
   attachment points.  Once attached, it is used for filtering traffic
   using the match criteria in the ACE's and taking appropriate
   action(s) that have been configured against that ACE.  In order to
   apply an ACL to any attachment point, vendors would have to augment
   the ACL YANG model.

1.1.  Definitions and Acronyms

   ACE: Access Control Entry

   ACL: Access Control List




Jethanandani, et al.     Expires March 16, 2018                 [Page 3]


Internet-Draft               ACL YANG model               September 2017


   DSCP: Differentiated Services Code Point

   ICMP: Internet Control Message Protocol

   IP: Internet Protocol

   IPv4: Internet Protocol version 4

   IPv6: Internet Protocol version 6

   MAC: Media Access Control

   TCP: Transmission Control Protocol

2.  Problem Statement

   This document defines a YANG [RFC6020] data model for the
   configuration of ACLs.  It is very important that model can be easily
   used by applications/attachments.

   ACL implementations in every device may vary greatly in terms of the
   filter constructs and actions that they support.  Therefore this
   draft proposes a model that can be augmented by standard extensions
   and vendor proprietary models.

3.  Understanding ACL's Filters and Actions

   Although different vendors have different ACL data models, there is a
   common understanding of what access control list (ACL) is.  A network
   system usually have a list of ACLs, and each ACL contains an ordered
   list of rules, also known as access list entries - ACEs.  Each ACE
   has a group of match criteria and a group of action criteria.  The
   match criteria consist of packet header matching.  It as also
   possible for ACE to match on metadata, if supported by the vendor.
   Packet header matching applies to fields visible in the packet such
   as address or class of service or port numbers.  Metadata matching
   applies to fields associated with the packet, but not in the packet
   header such as input interface, packet length, or source or
   destination prefix length.  The actions can be any sort of operation
   from logging to rate limiting or dropping to simply forwarding.
   Actions on the first matching ACE are applied with no processing of
   subsequent ACEs.

   The model also includes a container to hold overall operational state
   for each ACL and operational state for each ACE.  One ACL can be
   applied to multiple targets within the device, such as interfaces of
   a networked device, applications or features running in the device,
   etc.  When applied to interfaces of a networked device, the ACL is



Jethanandani, et al.     Expires March 16, 2018                 [Page 4]


Internet-Draft               ACL YANG model               September 2017


   applied in a direction which indicates if it should be applied to
   packet entering (input) or leaving the device (output).  An example
   in the appendix shows how to express it in YANG model.

   This draft tries to address the commonalities between all vendors and
   create a common model, which can be augmented with proprietary
   models.  The base model is simple and with this design we hope to
   achieve enough flexibility for each vendor to extend the base model.
   The use of feature statements in the document allows vendors to
   advertise match rules they support.

3.1.  ACL Modules

   There are two YANG modules in the model.  The first module, "ietf-
   access-control-list", defines generic ACL aspects which are common to
   all ACLs regardless of their type or vendor.  In effect, the module
   can be viewed as providing a generic ACL "superclass".  It imports
   the second module, "ietf-packet-fields".  The match container in
   "ietf-access-control-list" uses groupings in "ietf-packet-fields".
   The combination of if-feature checks and must statements allow for
   the selection of relevant match fields that a user can define rules
   for.

   If there is a need to define new "matches" choice, such as IPFIX
   [RFC5101], the container "matches" can be augmented.

   For a reference to the annotations used in the diagram below, see
   YANG Tree Diagrams [I-D.ietf-netmod-yang-tree-diagrams].

 module: ietf-access-control-list
     +--rw access-lists
        +--rw acl* [acl-type acl-name]
           +--rw acl-name         string
           +--rw acl-type         acl-type
           +--ro acl-oper-data
           +--rw aces
              +--rw ace* [rule-name]
                 +--rw rule-name        string
                 +--rw matches
                 |  +--rw l2-acl {l2-acl}?
                 |  |  +--rw destination-mac-address?        yang:mac-ad
 dress
                 |  |  +--rw destination-mac-address-mask?   yang:mac-ad
 dress
                 |  |  +--rw source-mac-address?             yang:mac-ad
 dress
                 |  |  +--rw source-mac-address-mask?        yang:mac-ad
 dress



Jethanandani, et al.     Expires March 16, 2018                 [Page 5]


Internet-Draft               ACL YANG model               September 2017


                 |  |  +--rw ether-type?                     string
                 |  +--rw ipv4-acl {ipv4-acl}?
                 |  |  +--rw dscp?                       inet:dscp
                 |  |  +--rw ecn?                        uint8
                 |  |  +--rw length?                     uint16
                 |  |  +--rw ttl?                        uint8
                 |  |  +--rw protocol?                   uint8
                 |  |  +--rw source-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operation?    operator
                 |  |  +--rw destination-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operations?   operator
                 |  |  +--rw ihl?                        uint8
                 |  |  +--rw flags?                      bits
                 |  |  +--rw offset?                     uint16
                 |  |  +--rw identification?             uint16
                 |  |  +--rw destination-ipv4-network?   inet:ipv4-prefi
 x
                 |  |  +--rw source-ipv4-network?        inet:ipv4-prefi
 x
                 |  +--rw ipv6-acl {ipv6-acl}?
                 |  |  +--rw dscp?                       inet:dscp
                 |  |  +--rw ecn?                        uint8
                 |  |  +--rw length?                     uint16
                 |  |  +--rw ttl?                        uint8
                 |  |  +--rw protocol?                   uint8
                 |  |  +--rw source-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operation?    operator
                 |  |  +--rw destination-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operations?   operator
                 |  |  +--rw next-header?                uint8
                 |  |  +--rw destination-ipv6-network?   inet:ipv6-prefi
 x
                 |  |  +--rw source-ipv6-network?        inet:ipv6-prefi
 x
                 |  |  +--rw flow-label?                 inet:ipv6-flow-
 label
                 |  +--rw l2-l3-ipv4-acl {mixed-ipv4-acl}?
                 |  |  +--rw destination-mac-address?        yang:mac-ad
 dress
                 |  |  +--rw destination-mac-address-mask?   yang:mac-ad



Jethanandani, et al.     Expires March 16, 2018                 [Page 6]


Internet-Draft               ACL YANG model               September 2017


 dress
                 |  |  +--rw source-mac-address?             yang:mac-ad
 dress
                 |  |  +--rw source-mac-address-mask?        yang:mac-ad
 dress
                 |  |  +--rw ether-type?                     string
                 |  |  +--rw dscp?                           inet:dscp
                 |  |  +--rw ecn?                            uint8
                 |  |  +--rw length?                         uint16
                 |  |  +--rw ttl?                            uint8
                 |  |  +--rw protocol?                       uint8
                 |  |  +--rw source-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operation?    operator
                 |  |  +--rw destination-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operations?   operator
                 |  |  +--rw ihl?                            uint8
                 |  |  +--rw flags?                          bits
                 |  |  +--rw offset?                         uint16
                 |  |  +--rw identification?                 uint16
                 |  |  +--rw destination-ipv4-network?       inet:ipv4-p
 refix
                 |  |  +--rw source-ipv4-network?            inet:ipv4-p
 refix
                 |  +--rw l2-l3-ipv6-acl {mixed-ipv6-acl}?
                 |  |  +--rw destination-mac-address?        yang:mac-ad
 dress
                 |  |  +--rw destination-mac-address-mask?   yang:mac-ad
 dress
                 |  |  +--rw source-mac-address?             yang:mac-ad
 dress
                 |  |  +--rw source-mac-address-mask?        yang:mac-ad
 dress
                 |  |  +--rw ether-type?                     string
                 |  |  +--rw dscp?                           inet:dscp
                 |  |  +--rw ecn?                            uint8
                 |  |  +--rw length?                         uint16
                 |  |  +--rw ttl?                            uint8
                 |  |  +--rw protocol?                       uint8
                 |  |  +--rw source-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operation?    operator
                 |  |  +--rw destination-port-range!
                 |  |  |  +--rw lower-port    inet:port-number



Jethanandani, et al.     Expires March 16, 2018                 [Page 7]


Internet-Draft               ACL YANG model               September 2017


                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operations?   operator
                 |  |  +--rw next-header?                    uint8
                 |  |  +--rw destination-ipv6-network?       inet:ipv6-p
 refix
                 |  |  +--rw source-ipv6-network?            inet:ipv6-p
 refix
                 |  |  +--rw flow-label?
                 |  |          inet:ipv6-flow-label
                 |  +--rw l2-l3-ipv4-ipv6-acl {l2-l3-ipv4-ipv6-acl}?
                 |  |  +--rw destination-mac-address?        yang:mac-ad
 dress
                 |  |  +--rw destination-mac-address-mask?   yang:mac-ad
 dress
                 |  |  +--rw source-mac-address?             yang:mac-ad
 dress
                 |  |  +--rw source-mac-address-mask?        yang:mac-ad
 dress
                 |  |  +--rw ether-type?                     string
                 |  |  +--rw dscp?                           inet:dscp
                 |  |  +--rw ecn?                            uint8
                 |  |  +--rw length?                         uint16
                 |  |  +--rw ttl?                            uint8
                 |  |  +--rw protocol?                       uint8
                 |  |  +--rw source-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operation?    operator
                 |  |  +--rw destination-port-range!
                 |  |  |  +--rw lower-port    inet:port-number
                 |  |  |  +--rw upper-port?   inet:port-number
                 |  |  |  +--rw operations?   operator
                 |  |  +--rw ihl?                            uint8
                 |  |  +--rw flags?                          bits
                 |  |  +--rw offset?                         uint16
                 |  |  +--rw identification?                 uint16
                 |  |  +--rw destination-ipv4-network?       inet:ipv4-p
 refix
                 |  |  +--rw source-ipv4-network?            inet:ipv4-p
 refix
                 |  |  +--rw next-header?                    uint8
                 |  |  +--rw destination-ipv6-network?       inet:ipv6-p
 refix
                 |  |  +--rw source-ipv6-network?            inet:ipv6-p
 refix
                 |  |  +--rw flow-label?
                 |  |          inet:ipv6-flow-label
                 |  +--rw tcp-acl {tcp-acl}?



Jethanandani, et al.     Expires March 16, 2018                 [Page 8]


Internet-Draft               ACL YANG model               September 2017


                 |  |  +--rw sequence-number?          uint32
                 |  |  +--rw acknowledgement-number?   uint32
                 |  |  +--rw data-offset?              uint8
                 |  |  +--rw reserved?                 uint8
                 |  |  +--rw flags?                    bits
                 |  |  +--rw window-size?              uint16
                 |  |  +--rw urgent-pointer?           uint16
                 |  |  +--rw options?                  uint32
                 |  +--rw udp-acl {udp-acl}?
                 |  |  +--rw length?   uint16
                 |  +--rw icmp-acl {icmp-acl}?
                 |  |  +--rw type?             uint8
                 |  |  +--rw code?             uint8
                 |  |  +--rw rest-of-header?   uint32
                 |  +--rw any-acl! {any-acl}?
                 |  +--rw interface?             if:interface-ref
                 +--rw actions
                 |  +--rw (packet-handling)?
                 |  |  +--:(deny)
                 |  |  |  +--rw deny?      empty
                 |  |  +--:(permit)
                 |  |     +--rw permit?    empty
                 |  +--rw logging?   boolean
                 +--ro ace-oper-data
                    +--ro match-counter?   yang:counter64

4.  ACL YANG Models

4.1.  IETF Access Control List module

   "ietf-access-control-list" is the standard top level module for
   access lists.  The "access-lists" container stores a list of "acl".
   Each "acl" has information identifying the access list by a
   name("acl-name") and a list("access-list-entries") of rules
   associated with the "acl-name".  Each of the entries in the
   list("access-list-entries"), indexed by the string "rule-name", has
   containers defining "matches" and "actions".

   The "matches" define criteria used to identify patterns in "ietf-
   packet-fields".  The "actions" define behavior to undertake once a
   "match" has been identified.  In addition to permit and deny for
   actions, a logging option allows for a match to be logged that can be
   used to determine which rule was matched upon.

<CODE BEGINS> file "ietf-access-control-list@2017-09-12.yang"

module ietf-access-control-list {
  namespace "urn:ietf:params:xml:ns:yang:ietf-access-control-list";



Jethanandani, et al.     Expires March 16, 2018                 [Page 9]


Internet-Draft               ACL YANG model               September 2017


  prefix acl;

  import ietf-yang-types {
    prefix yang;
  }

  import ietf-packet-fields {
    prefix packet-fields;
  }

  import ietf-interfaces {
    prefix if;
  }

  organization
    "IETF NETMOD (NETCONF Data Modeling Language)
     Working Group";

  contact
    "WG Web: http://tools.ietf.org/wg/netmod/
     WG List: netmod@ietf.org

     Editor: Mahesh Jethanandani
             mjethanandani@gmail.com
     Editor: Lisa Huang
             lyihuang16@gmail.com
     Editor: Sonal Agarwal
             agarwaso@cisco.com
     Editor: Dana Blair
             dblair@cisco.com";

  description
    "This YANG module defines a component that describe the
     configuration of Access Control Lists (ACLs).

     Copyright (c) 2017 IETF Trust and the persons identified as
     the document authors.  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 2017-09-12 {



Jethanandani, et al.     Expires March 16, 2018                [Page 10]


Internet-Draft               ACL YANG model               September 2017


    description
      "Added feature and identity statements for different types
       of rule matches. Split the matching rules based on the
       feature statement and added a must statement within
       each container.";
    reference
      "RFC XXX: Network Access Control List (ACL) YANG Data Model.";
  }

  /*
   * Identities
   */
  identity acl-base {
    description
      "Base Access Control List type for all Access Control List type
      identifiers.";
  }

  identity ipv4-acl {
    base acl:acl-base;
    description
       "ACL that primarily matches on fields from the IPv4 header
       (e.g. IPv4 destination address) and layer 4 headers (e.g. TCP
       destination port).  An acl of type ipv4-acl does not contain
       matches on fields in the ethernet header or the IPv6 header.";
  }

  identity ipv6-acl {
    base acl:acl-base;
    description
      "ACL that primarily matches on fields from the IPv6 header
      (e.g. IPv6 destination address) and layer 4 headers (e.g. TCP
      destination port). An acl of type ipv6-acl does not contain
      matches on fields in the ethernet header or the IPv4 header.";
  }

  identity eth-acl {
    base acl:acl-base;
    description
      "ACL that primarily matches on fields in the ethernet header,
      like 10/100/1000baseT or WiFi Access Control List. An acl of
      type eth-acl does not contain matches on fields in the IPv4
      header, IPv6 header or layer 4 headers.";
  }

  identity mixed-l2-l3-ipv4-acl {
    base "acl:acl-base";




Jethanandani, et al.     Expires March 16, 2018                [Page 11]


Internet-Draft               ACL YANG model               September 2017


    description
      "ACL that contains a mix of entries that
       primarily match on fields in ethernet headers,
       entries that primarily match on IPv4 headers.
       Matching on layer 4 header fields may also exist in the
       list.";
  }

  identity mixed-l2-l3-ipv6-acl {
    base "acl:acl-base";

    description
      "ACL that contains a mix of entries that
       primarily match on fields in ethernet headers, entries
       that primarily match on fields in IPv6 headers. Matching on
       layer 4 header fields may also exist in the list.";
  }

  identity mixed-l2-l3-ipv4-ipv6-acl {
    base "acl:acl-base";

    description
      "ACL that contains a mix of entries that
       primarily match on fields in ethernet headers, entries
       that primarily match on fields in IPv4 headers, and entries
       that primarily match on fields in IPv6 headers. Matching on
       layer 4 header fields may also exist in the list.";
  }

  identity any-acl {
    base "acl:acl-base";

    description
      "ACL that can contain any pattern to match upon";
  }

  /*
   * Features
   */
  feature l2-acl {
    description
      "Layer 2 ACL supported";
  }

  feature ipv4-acl {
    description
      "Layer 3 IPv4 ACL supported";
  }



Jethanandani, et al.     Expires March 16, 2018                [Page 12]


Internet-Draft               ACL YANG model               September 2017


  feature ipv6-acl {
    description
      "Layer 3 IPv6 ACL supported";
  }

  feature mixed-ipv4-acl {
    description
      "Layer 2 and Layer 3 IPv4 ACL supported";
  }

  feature mixed-ipv6-acl {
    description
      "Layer 2 and Layer 3 IPv6 ACL supported";
  }

  feature l2-l3-ipv4-ipv6-acl {
    description
      "Layer 2 and any Layer 3 ACL supported.";
  }

  feature tcp-acl {
    description
      "TCP header ACL supported.";
  }

  feature udp-acl {
    description
      "UDP header ACL supported.";
  }

  feature icmp-acl {
    description
      "ICMP header ACL supported.";
  }

  feature any-acl {
    description
     "ACL for any pattern.";
  }

  /*
   * Typedefs
   */
  typedef acl-type {
    type identityref {
      base acl-base;
    }
    description



Jethanandani, et al.     Expires March 16, 2018                [Page 13]


Internet-Draft               ACL YANG model               September 2017


      "This type is used to refer to an Access Control List
      (ACL) type";
  }

  typedef acl-ref {
    type leafref {
      path "/access-lists/acl/acl-name";
    }
    description
      "This type is used by data models that need to reference an
      Access Control List";
  }

  /*
   * Configuration data nodes
   */
  container access-lists {
    description
      "This is a top level container for Access Control Lists.
       It can have one or more Access Control Lists.";
    list acl {
      key "acl-type acl-name";
      description
        "An Access Control List(ACL) is an ordered list of
         Access List Entries (ACE). Each Access Control Entry has a
         list of match criteria and a list of actions.
         Since there are several kinds of Access Control Lists
         implemented with different attributes for
         different vendors, this
         model accommodates customizing Access Control Lists for
         each kind and for each vendor.";
      leaf acl-name {
        type string;
        description
          "The name of access-list. A device MAY restrict the length
           and value of this name, possibly space and special
           characters are not allowed.";
      }
      leaf acl-type {
        type acl-type;
        description
          "Type of access control list. Indicates the primary intended
           type of match criteria (e.g. ethernet, IPv4, IPv6, mixed,
           etc) used in the list instance.";
      }
      container acl-oper-data {
        config false;
        description



Jethanandani, et al.     Expires March 16, 2018                [Page 14]


Internet-Draft               ACL YANG model               September 2017


          "Overall Access Control List operational data";
      }
      container aces {
        description
          "The access-list-entries container contains
           a list of access-list-entries(ACE).";
        list ace {
          key "rule-name";
          ordered-by user;
          description
            "List of access list entries(ACE)";
          leaf rule-name {
            type string;
            description
              "A unique name identifying this Access List
               Entry(ACE).";
          }

          container matches {
            description
              "The rules in this set determine what fields will be
               matched upon before any action is taken on them.
               The rules are selected based on the feature set
               defined by the server and the acl-type defined.";

            container l2-acl {
              if-feature l2-acl;
              must "../../../../acl-type = 'eth-acl'";
              uses packet-fields:acl-eth-header-fields;
              description
                "Rule set for L2 ACL.";
            }

            container ipv4-acl {
              if-feature ipv4-acl;
                  must "../../../../acl-type = 'ipv4-acl'";
              uses packet-fields:acl-ip-header-fields;
                  uses packet-fields:acl-ipv4-header-fields;
              description
                "Rule set that supports IPv4 headers.";
            }

            container ipv6-acl {
              if-feature ipv6-acl;
              must "../../../../acl-type = 'ipv6-acl'";
              uses packet-fields:acl-ip-header-fields;
              uses packet-fields:acl-ipv6-header-fields;
              description



Jethanandani, et al.     Expires March 16, 2018                [Page 15]


Internet-Draft               ACL YANG model               September 2017


                "Rule set that supports IPv6 headers.";
            }

            container l2-l3-ipv4-acl {
              if-feature mixed-ipv4-acl;
              must "../../../../acl-type = 'mixed-l2-l3-ipv4-acl'";
              uses packet-fields:acl-eth-header-fields;
              uses packet-fields:acl-ip-header-fields;
              uses packet-fields:acl-ipv4-header-fields;
              description
                "Rule set that is a logical AND (&&) of l2
                 and ipv4 headers.";
            }

            container l2-l3-ipv6-acl {
              if-feature mixed-ipv6-acl;
              must "../../../../acl-type = 'mixed-l2-l3-ipv6-acl'";
              uses packet-fields:acl-eth-header-fields;
              uses packet-fields:acl-ip-header-fields;
              uses packet-fields:acl-ipv6-header-fields;
              description
                "Rule set that is a logical AND (&&) of L2
                 && IPv6 headers.";
            }

            container l2-l3-ipv4-ipv6-acl {
              if-feature l2-l3-ipv4-ipv6-acl;
              must "../../../../acl-type = 'mixed-l2-l3-ipv4-ipv6-acl'";
              uses packet-fields:acl-eth-header-fields;
              uses packet-fields:acl-ip-header-fields;
              uses packet-fields:acl-ipv4-header-fields;
              uses packet-fields:acl-ipv6-header-fields;
              description
                "Rule set that is a logical AND (&&) of L2
                 && IPv4 && IPv6 headers.";
            }

            container tcp-acl {
              if-feature tcp-acl;
              uses packet-fields:acl-tcp-header-fields;
              description
                "Rule set that defines TCP headers.";
            }

            container udp-acl {
              if-feature udp-acl;
              uses packet-fields:acl-udp-header-fields;
              description



Jethanandani, et al.     Expires March 16, 2018                [Page 16]


Internet-Draft               ACL YANG model               September 2017


                "Rule set that defines UDP headers.";
            }

            container icmp-acl {
              if-feature icmp-acl;
              uses packet-fields:acl-icmp-header-fields;
              description
                "Rule set that defines ICMP headers.";
            }

            container any-acl {
              if-feature any-acl;
              must "../../../../acl-type = 'any-acl'";
              presence "Matches any";
              description
                "Rule set that allows for a any ACL.";
            }

            leaf interface {
              type if:interface-ref;
              description
                "Interface name that is specified to
                 match upon.";
            }
          }

          container actions {
            description
              "Definitions of action criteria for this Access List
               Entry.";
            choice packet-handling {
              default "deny";
              description
                "Packet handling action.";
              case deny {
                leaf deny {
                  type empty;
                  description
                    "Deny action.";
                }
              }
              case permit {
                leaf permit {
                  type empty;
                  description
                    "Permit action.";
                }
              }



Jethanandani, et al.     Expires March 16, 2018                [Page 17]


Internet-Draft               ACL YANG model               September 2017


            }
            leaf logging {
              type boolean;
              default "false";
              description
                "Log the rule on which the match occurred.
                 Setting the value to true enables logging,
                 whereas setting the value to false disables it.";
            }
          }
          /*
           * Operational state data nodes
           */
          container ace-oper-data {
            config false;
            description
              "Operational data for this Access List Entry.";
            leaf match-counter {
              type yang:counter64;
              description
                "Number of matches for this Access List Entry";
            }
          }
        }
      }
    }
  }
}

<CODE ENDS>

4.2.  IETF Packet Fields module

   The packet fields module defines the necessary groups for matching on
   fields in the packet including ethernet, ipv4, ipv6, and transport
   layer fields.  The 'acl-type' node determines which of these fields
   get included for any given ACL with the exception of TCP, UDP and
   ICMP header fields.  Those fields can be used in conjunction with any
   of the above layer 2 or layer 3 fields.

   Since the number of match criteria is very large, the base draft does
   not include these directly but references them by "uses" to keep the
   base module simple.  In case more match conditions are needed, those
   can be added by augmenting choices within container "matches" in
   ietf-access-control-list.yang model.

<CODE BEGINS> file "ietf-packet-fields@2017-09-12.yang"




Jethanandani, et al.     Expires March 16, 2018                [Page 18]


Internet-Draft               ACL YANG model               September 2017


module ietf-packet-fields {
  namespace "urn:ietf:params:xml:ns:yang:ietf-packet-fields";
  prefix packet-fields;

  import ietf-inet-types {
    prefix inet;
  }

  import ietf-yang-types {
    prefix yang;
  }

  organization
    "IETF NETMOD (NETCONF Data Modeling Language) Working
     Group";

  contact
    "WG Web: http://tools.ietf.org/wg/netmod/
     WG List: netmod@ietf.org

     Editor: Mahesh Jethanandani
             mjethanandani@gmail.com
     Editor: Lisa Huang
             lyihuang16@gmail.com
     Editor: Sonal Agarwal
             agarwaso@cisco.com
     Editor: Dana Blair
             dblair@cisco.com";

  description
    "This YANG module defines groupings that are used by
    ietf-access-control-list YANG module. Their usage is not
    limited to ietf-access-control-list and can be
    used anywhere as applicable.
    Copyright (c) 2017 IETF Trust and the persons identified as
    the document authors.  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 2017-09-12 {
    description



Jethanandani, et al.     Expires March 16, 2018                [Page 19]


Internet-Draft               ACL YANG model               September 2017


      "Added header fields for TCP, UDP, and ICMP.";
    reference
      "RFC XXX: Network Access Control List (ACL) YANG Data Model.";
  }

  /*
   * Typedefs
   */
  typedef operator {
    type enumeration {
      enum lt {
        description
          "Less than.";
      }
      enum gt {
        description
          "Greater than.";
      }
      enum eq {
        description
          "Equal to.";
      }
      enum neq {
        description
          "Not equal to.";
      }
    }
    description
      "The source and destination port range definitions
       can be further qualified using an operator. An
       operator is needed only if lower-port is specified
       and upper-port is not specified. The operator
       therefore further qualifies lower-port only.";
  }

  grouping acl-transport-header-fields {
    description
      "Transport header fields";
    container source-port-range {
      presence "Enables setting source port range";
      description
        "Inclusive range representing source ports to be used.
         When only lower-port is present, it represents a single
         port and eq operator is assumed to be default.

         When both lower-port and upper-port are specified,
         it implies a range inclusive of both values.




Jethanandani, et al.     Expires March 16, 2018                [Page 20]


Internet-Draft               ACL YANG model               September 2017


         If no port is specified, 'any' (wildcard) is assumed.";

      leaf lower-port {
        type inet:port-number;
        mandatory true;
        description
          "Lower boundary for port.";
      }
      leaf upper-port {
        type inet:port-number;
        must ". >= ../lower-port" {
          error-message
          "The upper-port must be greater than or equal
           to lower-port";
        }
        description
          "Upper boundary for port. If it exists, the upper port
           must be greater or equal to lower-port.";
      }
      leaf operation {
        type operator;
        must "(../lower-port and not(../upper-port))" {
          error-message
            "If lower-port is specified, and an operator is also
             specified, then upper-port should not be specified.";
          description
            "If lower-port is specified, and an operator is also
             specified, then upper-port should not be specified.";
        }
        default eq;
        description
          "Operator to be applied on the lower-port.";
      }
    }

    container destination-port-range {
      presence "Enables setting destination port range";
      description
        "Inclusive range representing destination ports to be used.
         When only lower-port is present, it represents a single
         port and eq operator is assumed to be default.

         When both lower-port and upper-port are specified,
         it implies a range inclusive of both values.

         If no port is specified, 'any' (wildcard) is assumed. ";

      leaf lower-port {



Jethanandani, et al.     Expires March 16, 2018                [Page 21]


Internet-Draft               ACL YANG model               September 2017


        type inet:port-number;
        mandatory true;
        description
          "Lower boundary for port.";
      }
      leaf upper-port {
        type inet:port-number;
        must ". >= ../lower-port" {
          error-message
            "The upper-port must be greater than or equal
             to lower-port";
        }
        description
          "Upper boundary for port. If existing, the upper port must
          be greater or equal to lower-port";
      }
      leaf operations {
        type operator;
        must "(../lower-port and not(../upper-port))" {
          error-message
            "If lower-port is specified, and an operator is also
             specified, then upper-port should not be specified.";
          description
            "If lower-port is specified, and an operator is also
             specified, then upper-port should not be specified.";
        }
        default eq;
        description
          "Operator to be applied on the lower-port.";
      }
    }
  }

  grouping acl-ip-header-fields {
    description
      "IP header fields common to ipv4 and ipv6";
    reference
      "RFC 791.";

    leaf dscp {
      type inet:dscp;
      description
        "Differentiated Services Code Point.";
      reference
        "RFC 2474: Definition of Differentiated services field
         (DS field) in the IPv4 and IPv6 headers.";
    }




Jethanandani, et al.     Expires March 16, 2018                [Page 22]


Internet-Draft               ACL YANG model               September 2017


    leaf ecn {
      type uint8 {
        range 0..3;
      }
      description
        "Explicit Congestion Notification.";
      reference
        "RFC 3168.";
    }

    leaf length {
      type uint16;
      description
        "In IPv4 header field, this field is known as the Total Length.
         Total Length is the length of the datagram, measured in octets,
         including internet header and data.

         In IPv6 header field, this field is known as the Payload
         Length, the length of the IPv6 payload, i.e. the rest of
         the packet following the IPv6 header, in octets.";
      reference
        "RFC 719, RFC 2460";
    }

    leaf ttl {
      type uint8;
      description
        "This field indicates the maximum time the datagram is allowed
         to remain in the internet system.  If this field contains the
         value zero, then the datagram must be destroyed.

         In IPv6, this field is known as the Hop Limit.";
      reference "RFC 719, RFC 2460";
    }

    leaf protocol {
      type uint8;
      description
        "Internet Protocol number.";
    }
    uses acl-transport-header-fields;
  }

  grouping acl-ipv4-header-fields {
    description
      "Fields in IPv4 header.";

    leaf ihl {



Jethanandani, et al.     Expires March 16, 2018                [Page 23]


Internet-Draft               ACL YANG model               September 2017


      type uint8 {
        range "5..60";
      }
      description
        "An IPv4 header field, the Internet Header Length (IHL) is
         the length of the internet header in 32 bit words, and
         thus points to the beginning of the data. Note that the
         minimum value for a correct header is 5.";
    }

    leaf flags {
      type bits {
        bit reserved {
          position 0;
          description
            "Reserved. Must be zero.";
        }
        bit fragment {
          position 1;
          description
            "Setting value to 0 indicates may fragment, while setting
             the value to 1 indicates do not fragment.";
        }
        bit more {
          position 2;
          description
            "Setting the value to 0 indicates this is the last fragment,
             and setting the value to 1 indicates more fragments are
             coming.";
        }
      }
      description
        "Bit definitions for the flags field in IPv4 header.";
    }

    leaf offset {
      type uint16 {
        range "20..65535";
      }
      description
        "The fragment offset is measured in units of 8 octets (64 bits).
         The first fragment has offset zero. The length is 13 bits";
    }

    leaf identification {
      type uint16;
      description
        "An identifying value assigned by the sender to aid in



Jethanandani, et al.     Expires March 16, 2018                [Page 24]


Internet-Draft               ACL YANG model               September 2017


         assembling the fragments of a datagram.";
    }

    leaf destination-ipv4-network {
      type inet:ipv4-prefix;
      description
        "Destination IPv4 address prefix.";
    }
    leaf source-ipv4-network {
      type inet:ipv4-prefix;
      description
        "Source IPv4 address prefix.";
    }
  }

  grouping acl-ipv6-header-fields {
    description
      "Fields in IPv6 header";

    leaf next-header {
      type uint8;
      description
        "Identifies the type of header immediately following the
         IPv6 header. Uses the same values as the IPv4 Protocol
         field.";
      reference
        "RFC 2460";
    }

    leaf destination-ipv6-network {
      type inet:ipv6-prefix;
      description
        "Destination IPv6 address prefix.";
    }

    leaf source-ipv6-network {
      type inet:ipv6-prefix;
      description
        "Source IPv6 address prefix.";
    }

    leaf flow-label {
      type inet:ipv6-flow-label;
      description
        "IPv6 Flow label.";
    }
    reference
      "RFC 4291: IP Version 6 Addressing Architecture



Jethanandani, et al.     Expires March 16, 2018                [Page 25]


Internet-Draft               ACL YANG model               September 2017


       RFC 4007: IPv6 Scoped Address Architecture
       RFC 5952: A Recommendation for IPv6 Address Text
                 Representation";
  }

  grouping acl-eth-header-fields {
    description
      "Fields in Ethernet header.";

    leaf destination-mac-address {
      type yang:mac-address;
      description
        "Destination IEEE 802 MAC address.";
    }
    leaf destination-mac-address-mask {
      type yang:mac-address;
      description
        "Destination IEEE 802 MAC address mask.";
    }
    leaf source-mac-address {
      type yang:mac-address;
      description
        "Source IEEE 802 MAC address.";
    }
    leaf source-mac-address-mask {
      type yang:mac-address;
      description
        "Source IEEE 802 MAC address mask.";
    }
    leaf ether-type {
      type string {
        pattern '[0-9a-fA-F]{4}';
      }
      description
        "The Ethernet Type (or Length) value represented
         in the canonical order defined by IEEE 802.
         The canonical representation uses lowercase
         characters.

         Note: This is not the most ideal way to define
         ether-types. Ether-types are well known types
         and are registered with RAC in IEEE. So they
         should well defined types with values. For now
         this model is defining it as a string.
         There is a note out to IEEE that needs to be
         turned into a liaison statement asking them to
         define all ether-types for the industry to use.";
      reference



Jethanandani, et al.     Expires March 16, 2018                [Page 26]


Internet-Draft               ACL YANG model               September 2017


        "IEEE 802-2014 Clause 9.2";
    }
    reference
      "IEEE 802: IEEE Standard for Local and Metropolitan
       Area Networks: Overview and Architecture.";
  }

  grouping acl-tcp-header-fields {
    description
      "Collection of TCP header fields that can be used to
       setup a match filter.";

    leaf sequence-number {
      type uint32;
      description
        "Sequence number that appears in the packet.";
    }

    leaf acknowledgement-number {
      type uint32;
      description
        "The acknowledgement number that appears in the
         packet.";
    }

    leaf data-offset {
      type uint8 {
        range "5..15";
      }
      description
        "Specifies the size of the TCP header in 32-bit
         words. The minimum size header is 5 words and
         the maximum is 15 words thus giving the minimum
         size of 20 bytes and maximum of 60 bytes,
         allowing for up to 40 bytes of options in the
         header.";
    }

    leaf reserved {
      type uint8;
      description
        "Reserved for future use.";
    }

    leaf flags {
      type bits {
        bit ns {
          position 0;



Jethanandani, et al.     Expires March 16, 2018                [Page 27]


Internet-Draft               ACL YANG model               September 2017


          description
            "ECN-nonce concealment protection";
          reference "RFC 3540).";
        }
        bit cwr {
          position 1;
          description
            "Congestion Window Reduced (CWR) flag is set by
             the sending host to indicate that it received
             a TCP segment with the ECE flag set and had
             responded in congestion control mechanism.";
          reference "RFC 3168";
        }
        bit ece {
          position 2;
          description
            "ECN-Echo has a dual role, depending on the value
             of the SYN flag. It indicates:
             If the SYN flag is set (1), that the TCP peer is ECN
             capable. If the SYN flag is clear (0), that a packet
             with Congestion Experienced flag set (ECN=11) in IP
             header was received during normal transmission
             (added to header by RFC 3168). This serves as an
             indication of network congestion (or impending
             congestion) to the TCP sender.";
        }
        bit urg {
          position 3;
          description
            "Indicates that the Urgent pointer field is significant.";
        }
        bit ack {
          position 4;
          description
            "Indicates that the Acknowledgment field is significant.
             All packets after the initial SYN packet sent by the
             client should have this flag set.";
        }
        bit psh {
          position 5;
          description
            "Push function. Asks to push the buffered data to the
             receiving application.";
        }
        bit rst {
          position 6;
          description
            "Reset the connection.";



Jethanandani, et al.     Expires March 16, 2018                [Page 28]


Internet-Draft               ACL YANG model               September 2017


        }
        bit syn {
          position 7;
          description
            "Synchronize sequence numbers. Only the first packet
             sent from each end should have this flag set. Some
             other flags and fields change meaning based on this
             flag, and some are only valid for when it is set,
             and others when it is clear.";
        }
        bit fin {
          position 8;
          description
            "Last package from sender.";
        }
      }
      description
        "Also known as Control Bits. Contains 9 1-bit flags.";
    }

    leaf window-size {
      type uint16;
      description
        "The size of the receive window, which specifies
         the number of window size units (by default,
         bytes) (beyond the segment identified by the
         sequence number in the acknowledgment field)
         that the sender of this segment is currently
         willing to receive.";
    }

    leaf urgent-pointer {
      type uint16;
      description
        "This field is an offset from the sequence number
         indicating the last urgent data byte.";
    }

    leaf options {
      type uint32;
      description
        "The length of this field is determined by the
         data offset field. Options have up to three
         fields: Option-Kind (1 byte), Option-Length
         (1 byte), Option-Data (variable). The Option-Kind
         field indicates the type of option, and is the
         only field that is not optional. Depending on
         what kind of option we are dealing with,



Jethanandani, et al.     Expires March 16, 2018                [Page 29]


Internet-Draft               ACL YANG model               September 2017


         the next two fields may be set: the Option-Length
         field indicates the total length of the option,
         and the Option-Data field contains the value of
         the option, if applicable.";
    }
  }

  grouping acl-udp-header-fields {
    description
      "Collection of UDP header fields that can be used
       to setup a match filter.";

    leaf length {
      type uint16;
      description
        "A field that specifies the length in bytes of
         the UDP header and UDP data. The minimum
         length is 8 bytes because that is the length of
         the header. The field size sets a theoretical
         limit of 65,535 bytes (8 byte header + 65,527
         bytes of data) for a UDP datagram. However the
         actual limit for the data length, which is
         imposed by the underlying IPv4 protocol, is
         65,507 bytes (65,535 minus 8 byte UDP header
         minus 20 byte IP header).

         In IPv6 jumbograms it is possible to have
         UDP packets of size greater than 65,535 bytes.
         RFC 2675 specifies that the length field is set
         to zero if the length of the UDP header plus
         UDP data is greater than 65,535.";
    }
  }

  grouping acl-icmp-header-fields {
    description
      "Collection of ICMP header fields that can be
       used to setup a match filter.";

    leaf type {
      type uint8;
      description
        "Also known as Control messages.";
      reference "RFC 792";
    }

    leaf code {
      type uint8;



Jethanandani, et al.     Expires March 16, 2018                [Page 30]


Internet-Draft               ACL YANG model               September 2017


      description
        "ICMP subtype. Also known as Control messages.";
    }

    leaf rest-of-header {
      type uint32;
      description
        "Four-bytes field, contents vary based on the
         ICMP type and code.";
    }
  }
}

<CODE ENDS>

4.3.  An ACL Example

   Requirement: Deny tcp traffic from 10.10.10.1/24, destined to
   11.11.11.1/24.

   Here is the acl configuration xml for this Access Control List:






























Jethanandani, et al.     Expires March 16, 2018                [Page 31]


Internet-Draft               ACL YANG model               September 2017


   <?xml version='1.0' encoding='UTF-8'?>
     <data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
       <access-lists xmlns="urn:ietf:params:xml:ns:yang:
        ietf-access-control-list">
         <acl>
           <acl-name>sample-ipv4-acl</acl-name>
           <acl-type>ipv4-acl</acl-type>
           <aces>
             <ace>
               <rule-name>rule1</rule-name>
               <matches>
                 <ipv4-acl>
                   <protocol>tcp</protocol>
                   <destination-ipv4-network>
                     11.11.11.1/24
                   </destination-ipv4-network>
                   <source-ipv4-network>
                     10.10.10.1/24
                   </source-ipv4-network>
                 </ipv4-acl>
               </matches>
               <actions>
                 <packet-handling>deny</packet-handling>
               </actions>
             </ace>
           </aces>
         </acl>
       </access-lists>
     </data>


   The acl and aces can be described in CLI as the following:

         access-list ipv4 sample-ipv4-acl
         deny tcp 10.10.10.1/24 11.11.11.1/24

4.4.  Port Range Usage Example

   When a lower-port and an upper-port are both present, it represents a
   range between lower-port and upper-port with both the lower-port and
   upper-port are included.  When only a lower-port presents, it
   represents a single port.

   With the follow XML snippet:







Jethanandani, et al.     Expires March 16, 2018                [Page 32]


Internet-Draft               ACL YANG model               September 2017


        <source-port-range>
          <lower-port>16384</lower-port>
          <upper-port>16387</upper-port>
        </source-port-range>

   This represents source ports 16384,16385, 16386, and 16387.

   With the follow XML snippet:

         <source-port-range>
           <lower-port>16384</lower-port>
           <upper-port>65535</upper-port>
         </source-port-range>

   This represents source ports greater than/equal to 16384 and less
   than equal to 65535.

   With the follow XML snippet:

         <source-port-range>
           <lower-port>21</lower-port>
         </source-port-range>

   This represents port 21.

   With the following XML snippet, the configuration is specifying all
   ports that are not equal to 21.

         <source-port-range>
           <lower-port>21</lower-port>
           <operations>neq</operations>
         </source-port-range>


5.  Security Considerations

   The YANG module defined in this memo is designed to be accessed via
   the NETCONF [RFC6241].  The lowest NETCONF layer is the secure
   transport layer and the mandatory-to-implement secure transport is
   SSH [RFC6242].  The NETCONF Access Control Model ( NACM [RFC6536])
   provides the means to restrict access for particular NETCONF users to
   a pre-configured subset of all available NETCONF protocol operations
   and content.

   There are a number of data nodes defined in the YANG module which are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable
   in some network environments.  Write operations (e.g., <edit-config>)



Jethanandani, et al.     Expires March 16, 2018                [Page 33]


Internet-Draft               ACL YANG model               September 2017


   to these data nodes without proper protection can have a negative
   effect on network operations.

   These are the subtrees and data nodes and their sensitivity/
   vulnerability:

   /access-lists/acl/access-list-entries: This list specifies all the
   configured access list entries on the device.  Unauthorized write
   access to this list can allow intruders to access and control the
   system.  Unauthorized read access to this list can allow intruders to
   spoof packets with authorized addresses thereby compromising the
   system.

6.  IANA Considerations

   This document registers a URI in the IETF XML registry [RFC3688].
   Following the format in RFC 3688, the following registration is
   requested to be made:

   URI: urn:ietf:params:xml:ns:yang:ietf-access-control-list

   URI: urn:ietf:params:xml:ns:yang:ietf-packet-fields

   Registrant Contact: The IESG.

   XML: N/A, the requested URI is an XML namespace.

   This document registers a YANG module in the YANG Module Names
   registry [RFC6020].

   name: ietf-access-control-list namespace:
   urn:ietf:params:xml:ns:yang:ietf-access-control-list prefix: ietf-acl
   reference: RFC XXXX

   name: ietf-packet-fields namespace: urn:ietf:params:xml:ns:yang:ietf-
   packet-fields prefix: ietf-packet-fields reference: RFC XXXX

7.  Acknowledgements

   Alex Clemm, Andy Bierman and Lisa Huang started it by sketching out
   an initial IETF draft in several past IETF meetings.  That draft
   included an ACL YANG model structure and a rich set of match filters,
   and acknowledged contributions by Louis Fourie, Dana Blair, Tula
   Kraiser, Patrick Gili, George Serpa, Martin Bjorklund, Kent Watsen,
   and Phil Shafer.  Many people have reviewed the various earlier
   drafts that made the draft went into IETF charter.





Jethanandani, et al.     Expires March 16, 2018                [Page 34]


Internet-Draft               ACL YANG model               September 2017


   Dean Bogdanovic, Kiran Agrahara Sreenivasa, Lisa Huang, and Dana
   Blair each evaluated the YANG model in previous drafts separately,
   and then worked together to created a ACL draft that was supported by
   different vendors.  That draft removed vendor specific features, and
   gave examples to allow vendors to extend in their own proprietary
   ACL.  The earlier draft was superseded with this updated draft and
   received more participation from many vendors.

   Authors would like to thank Jason Sterne, Lada Lhotka, Juergen
   Schoenwalder, and David Bannister for their review of and suggestions
   to the draft.

8.  Open Issues

   o  The current model does not support the concept of "containers"
      used to contain multiple addresses per rule entry.

   o  The model defines 'ether-type' node as a string.  Ideally, this
      should be a well defined list of all Ethernet Types assigned by
      IEEE.

9.  References

9.1.  Normative References

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004, <https://www.rfc-
              editor.org/info/rfc3688>.

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

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

   [RFC6242]  Wasserman, M., "Using the NETCONF Protocol over Secure
              Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
              <https://www.rfc-editor.org/info/rfc6242>.

   [RFC6536]  Bierman, A. and M. Bjorklund, "Network Configuration
              Protocol (NETCONF) Access Control Model", RFC 6536,
              DOI 10.17487/RFC6536, March 2012, <https://www.rfc-
              editor.org/info/rfc6536>.




Jethanandani, et al.     Expires March 16, 2018                [Page 35]


Internet-Draft               ACL YANG model               September 2017


9.2.  Informative References

   [I-D.ietf-netmod-yang-tree-diagrams]
              Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft-
              ietf-netmod-yang-tree-diagrams-01 (work in progress), June
              2017.

   [RFC5101]  Claise, B., Ed., "Specification of the IP Flow Information
              Export (IPFIX) Protocol for the Exchange of IP Traffic
              Flow Information", RFC 5101, DOI 10.17487/RFC5101, January
              2008, <https://www.rfc-editor.org/info/rfc5101>.

Appendix A.  Extending ACL model examples

A.1.  Example of extending existing model for route filtering

   With proposed modular design, it is easy to extend the model with
   other features.  Those features can be standard features, like route
   filters.  Route filters match on specific IP addresses or ranges of
   prefixes.  Much like ACLs, they include some match criteria and
   corresponding match action(s).  For that reason, it is very simple to
   extend existing ACL model with route filtering.  The combination of a
   route prefix and prefix length along with the type of match
   determines how route filters are evaluated against incoming routes.
   Different vendors have different match types and in this model we are
   using only ones that are common across all vendors participating in
   this draft.  As in this example, the base ACL model can be extended
   with company proprietary extensions, described in the next section.

 module: example-ext-route-filter
   augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces/ietf-acl:ac
 e/ietf-acl:matches:
     +--rw (route-prefix)?
        +--:(range)
           +--rw (ipv4-range)?
           |  +--:(v4-lower-bound)
           |  |  +--rw v4-lower-bound?   inet:ipv4-prefix
           |  +--:(v4-upper-bound)
           |     +--rw v4-upper-bound?   inet:ipv4-prefix
           +--rw (ipv6-range)?
              +--:(v6-lower-bound)
              |  +--rw v6-lower-bound?   inet:ipv6-prefix
              +--:(v6-upper-bound)
                 +--rw v6-upper-bound?   inet:ipv6-prefix

   file "example-ext-route-filter@2017-09-12.yang"
   module example-ext-route-filter {
     namespace "urn:ietf:params:xml:ns:yang:example-ext-route-filter";



Jethanandani, et al.     Expires March 16, 2018                [Page 36]


Internet-Draft               ACL YANG model               September 2017


     prefix example-ext-route-filter;

     import ietf-inet-types {
       prefix "inet";
     }
     import ietf-access-control-list {
       prefix "ietf-acl";
     }

     organization
       "Route model group.";

     contact
       "abc@abc.com";

     description "
       This module describes route filter as a collection of
       match prefixes. When specifying a match prefix, you
       can specify an exact match with a particular route or
       a less precise match. You can configure either a
       common action that applies to the entire list or an
       action associated with each prefix.
       ";
     revision 2017-09-12 {
       description
         "Creating Route-Filter extension model based on
         ietf-access-control-list model";
       reference "Example route filter";
     }

     augment "/ietf-acl:access-lists/ietf-acl:acl/" +
             "ietf-acl:aces/ietf-acl:ace/ietf-acl:matches" {
       description "
         This module augments the matches container in the ietf-acl
         module with route filter specific actions";

       choice route-prefix{
         description "Define route filter match criteria";
         case range {
           description
             "Route falls between the lower prefix/prefix-length
              and the upperprefix/prefix-length.";
           choice ipv4-range {
             description "Defines the IPv4 prefix range";
             leaf v4-lower-bound {
               type inet:ipv4-prefix;
               description
                 "Defines the lower IPv4 prefix/prefix length";



Jethanandani, et al.     Expires March 16, 2018                [Page 37]


Internet-Draft               ACL YANG model               September 2017


             }
             leaf v4-upper-bound {
               type inet:ipv4-prefix;
               description
                 "Defines the upper IPv4 prefix/prefix length";
             }
           }
           choice ipv6-range {
             description "Defines the IPv6 prefix/prefix range";
             leaf v6-lower-bound {
               type inet:ipv6-prefix;
               description
                 "Defines the lower IPv6 prefix/prefix length";
             }
             leaf v6-upper-bound {
               type inet:ipv6-prefix;
               description
                 "Defines the upper IPv6 prefix/prefix length";
             }
           }
         }
       }
     }
   }

A.2.  A company proprietary module example

   Access control list typically does not exist in isolation.  Instead,
   they are associated with a certain scope in which they are applied,
   for example, an interface of a set of interfaces.  How to attach an
   access control list to an interface (or other system artifact) is
   outside the scope of this model, as it depends on the specifics of
   the system model that is being applied.  However, in general, the
   general design pattern will involved adding a data node with a
   reference, or set of references, to ACLs that are to be applied to
   the interface.  For this purpose, the type definition "access-
   control-list-ref" can be used.

   Module "example-newco-acl" is an example of company proprietary model
   that augments "ietf-acl" module.  It shows how to use 'augment' with
   an XPath expression to add additional match criteria, action
   criteria, and default actions when no ACE matches found, as well how
   to attach an Access Control List to an interface.  All these are
   company proprietary extensions or system feature extensions.
   "example-newco-acl" is just an example and it is expected from
   vendors to create their own proprietary models.





Jethanandani, et al.     Expires March 16, 2018                [Page 38]


Internet-Draft               ACL YANG model               September 2017


   The following figure is the tree structure of example-newco-acl.  In
   this example, /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces/ietf-
   acl:ace/ietf-acl:matches are augmented with two new choices,
   protocol-payload-choice and metadata.  The protocol-payload-choice
   uses a grouping with an enumeration of all supported protocol values.
   Metadata matches apply to fields associated with the packet but not
   in the packet header such as input interface or overall packet
   length.  In other example, /ietf-acl:access-lists/ietf-acl:acl/ietf-
   acl:aces/ietf-acl:ace/ietf-acl:actions are augmented with new choice
   of actions.









































Jethanandani, et al.     Expires March 16, 2018                [Page 39]


Internet-Draft               ACL YANG model               September 2017


 module: example-newco-acl
   augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces/ietf-acl:ac
 e/ietf-acl:matches:
     +--rw (protocol-payload-choice)?
     |  +--:(protocol-payload)
     |     +--rw protocol-payload* [value-keyword]
     |        +--rw value-keyword    enumeration
     +--rw (metadata)?
        +--:(interface-name)
           +--rw interface-name* [input-interface]
              +--rw input-interface    ietf-if:interface-ref
   augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces/ietf-acl:ac
 e/ietf-acl:actions:
     +--rw (action)?
        +--:(count)
        |  +--rw count?                   string
        +--:(policer)
        |  +--rw policer?                 string
        +--:(hiearchical-policer)
           +--rw hierarchitacl-policer?   string
   augment /ietf-acl:access-lists/ietf-acl:acl:
     +--rw default-actions
        +--rw deny?   empty
   augment /ietf-if:interfaces/ietf-if:interface:
     +--rw acl
        +--rw acl-name?        ietf-acl:acl-ref
        +--ro match-counter?   yang:counter64
        +--rw (direction)?
           +--:(in)
           |  +--rw in?              empty
           +--:(out)
              +--rw out?             empty
   augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:aces/ietf-acl:ac
 e/ietf-acl:ace-oper-data:
     +--ro targets
        +--ro (interface)?
           +--:(interface-name)
              +--ro interface-name*   ietf-if:interface-ref

   module example-newco-acl {

     yang-version 1.1;

     namespace "urn:newco:params:xml:ns:yang:example-newco-acl";

     prefix example-newco-acl;

     import ietf-access-control-list {



Jethanandani, et al.     Expires March 16, 2018                [Page 40]


Internet-Draft               ACL YANG model               September 2017


       prefix "ietf-acl";
     }

     import ietf-interfaces {
       prefix "ietf-if";
     }

     import ietf-yang-types {
       prefix yang;
     }

     organization
       "Newco model group.";

     contact
       "abc@newco.com";
     description
       "This YANG module augments IETF ACL Yang.";

     revision 2017-09-12 {
       description
         "Creating NewCo proprietary extensions to ietf-acl model";

       reference
         "RFC XXXX: Network Access Control List (ACL)
          YANG Data  Model";
     }

     augment "/ietf-acl:access-lists/ietf-acl:acl/" +
             "ietf-acl:aces/ietf-acl:ace/" +
             "ietf-acl:matches" {
       description "Newco proprietary simple filter matches";
       choice protocol-payload-choice {
         description "Newo proprietary payload match condition";
         list protocol-payload {
           key value-keyword;
           ordered-by user;
           description "Match protocol payload";
           uses match-simple-payload-protocol-value;
         }
       }

       choice metadata {
         description "Newco proprietary interface match condition";
         list interface-name {
           key input-interface;
           ordered-by user;
           description "Match interface name";



Jethanandani, et al.     Expires March 16, 2018                [Page 41]


Internet-Draft               ACL YANG model               September 2017


           uses metadata;
         }
       }
     }

     augment "/ietf-acl:access-lists/ietf-acl:acl/" +
             "ietf-acl:aces/ietf-acl:ace/" +
             "ietf-acl:actions" {
       description "Newco proprietary simple filter actions";
       choice action {
         description "";
         case count {
           description "Count the packet in the named counter";
           leaf count {
             type string;
             description "";
           }
         }
         case policer {
           description "Name of policer to use to rate-limit traffic";
           leaf policer {
             type string;
             description "";
           }
         }
         case hiearchical-policer {
           description "Name of hierarchical policer to use to
                        rate-limit traffic";
           leaf hierarchitacl-policer {
             type string;
             description "";
           }
         }
       }
     }

     augment "/ietf-acl:access-lists/ietf-acl:acl" {
       description "Newco proprietary default action";
       container default-actions {
         description
           "Actions that occur if no access-list entry is matched.";
         leaf deny {
           type empty;
           description "";
         }
       }
     }




Jethanandani, et al.     Expires March 16, 2018                [Page 42]


Internet-Draft               ACL YANG model               September 2017


     grouping metadata {
       description
         "Fields associated with a packet which are not in
          the header.";
       leaf input-interface {
         type ietf-if:interface-ref {
           require-instance false;
         }
         description
           "Packet was received on this interface";
       }
     }

     grouping match-simple-payload-protocol-value {
       description "Newco proprietary payload";
       leaf value-keyword {
         type enumeration {
           enum icmp {
             description "Internet Control Message Protocol";
           }
           enum icmp6 {
             description "Internet Control Message Protocol Version 6";
           }
           enum range {
             description "Range of values";
           }
         }
         description "(null)";
       }
     }

     augment "/ietf-if:interfaces/ietf-if:interface" {
       description "Apply ACL to interfaces";
       container acl {
         description "ACL related properties.";
         leaf acl-name {
           type ietf-acl:acl-ref;
           description "Access Control List name.";
         }
         leaf match-counter {
           type yang:counter64;
           config false;

           description
             "Total match count for Access Control
              List on this interface";
         }
         choice direction {



Jethanandani, et al.     Expires March 16, 2018                [Page 43]


Internet-Draft               ACL YANG model               September 2017


           description "Applying ACL in which traffic direction";
           leaf in {
             type empty;
             description "Inbound traffic";
           }
           leaf out {
             type empty;
             description "Outbound traffic";
           }
         }
       }
     }

     augment "/ietf-acl:access-lists/ietf-acl:acl/" +
             "ietf-acl:aces/ietf-acl:ace/" +
             "ietf-acl:ace-oper-data" {
       description
         "This is an example on how to apply acl to a target to collect
          operational data";
       container targets {
         description "To which object is the ACL attached to";
         choice interface {
           description
             "Access Control List was attached to this interface";
           leaf-list interface-name{
             type ietf-if:interface-ref {
               require-instance true;
             }
             description "Attached to this interface name";
           }
         }
       }
     }
   }


   Draft authors expect that different vendors will provide their own
   yang models as in the example above, which is the augmentation of the
   base model

A.3.  Linux nftables

   As Linux platform is becoming more popular as networking platform,
   the Linux data model is changing.  Previously ACLs in Linux were
   highly protocol specific and different utilities were used (iptables,
   ip6tables, arptables, ebtables), so each one had separate data model.
   Recently, this has changed and a single utility, nftables, has been
   developed.  With a single application, it has a single data model for



Jethanandani, et al.     Expires March 16, 2018                [Page 44]


Internet-Draft               ACL YANG model               September 2017


   filewall filters and it follows very similarly to the ietf-access-
   control list module proposed in this draft.  The nftables support
   input and output ACEs and each ACE can be defined with match and
   action.

   The example in Section 4.3 can be configured using nftable tool as
   below.

         nft add table ip filter
         nft add chain filter input
         nft add rule ip filter input ip protocol tcp ip saddr \
             10.10.10.1/24 drop

   The configuration entries added in nftable would be.

         table ip filter {
           chain input {
             ip protocol tcp ip saddr 10.10.10.1/24 drop
           }
         }


   We can see that there are many similarities between Linux nftables
   and IETF ACL YANG data models and its extension models.  It should be
   fairly easy to do translation between ACL YANG model described in
   this draft and Linux nftables.

Authors' Addresses

   Mahesh Jethanandani
   Cisco Systems, Inc

   Email: mjethanandani@gmail.com


   Lisa Huang
   General Electric

   Email: lyihuang16@gmail.com


   Sonal Agarwal
   Cisco Systems, Inc.

   Email: agarwaso@cisco.com






Jethanandani, et al.     Expires March 16, 2018                [Page 45]


Internet-Draft               ACL YANG model               September 2017


   Dana Blair
   Cisco Systems, INc

   Email: dblair@cisco.com















































Jethanandani, et al.     Expires March 16, 2018                [Page 46]