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Extensions to the Access Control Lists (ACLs) YANG Model
draft-ietf-netmod-acl-extensions-01

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This is an older version of an Internet-Draft whose latest revision state is "Active".
Authors Oscar Gonzalez de Dios , Samier Barguil , Mohamed Boucadair , Qin Wu
Last updated 2023-03-10
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draft-ietf-netmod-acl-extensions-01
netmod                                                     O. G. D. Dios
Internet-Draft                                                S. Barguil
Intended status: Standards Track                              Telefonica
Expires: 11 September 2023                                  M. Boucadair
                                                                  Orange
                                                                   Q. Wu
                                                                  Huawei
                                                           10 March 2023

        Extensions to the Access Control Lists (ACLs) YANG Model
                  draft-ietf-netmod-acl-extensions-01

Abstract

   RFC 8519 defines a YANG data model for Access Control Lists (ACLs).
   This document discusses a set of extensions that fix many of the
   limitations of the ACL model as initially defined in RFC 8519.

   The document also defines an IANA-maintained module for ICMP types.

Discussion Venues

   This note is to be removed before publishing as an RFC.

   Discussion of this document takes place on the Network Modeling
   Working Group mailing list (netmod@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/netmod/.

   Source for this draft and an issue tracker can be found at
   https://github.com/boucadair/enhanced-acl-netmod.

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 11 September 2023.

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Copyright Notice

   Copyright (c) 2023 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 Revised BSD License text as
   described in Section 4.e of the Trust Legal Provisions and are
   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Problem Statement & Gap Analysis  . . . . . . . . . . . . . .   4
     3.1.  Suboptimal Configuration: Lack of Support for Lists of
           Prefixes  . . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Manageability: Impossibility to Use Aliases or Defined
           Sets  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
     3.3.  Bind ACLs to Devices, Not Only Interfaces . . . . . . . .   9
     3.4.  Partial or Lack of IPv4/IPv6 Fragment Handling  . . . . .   9
     3.5.  Suboptimal TCP Flags Handling . . . . . . . . . . . . . .   9
     3.6.  Rate-Limit Action . . . . . . . . . . . . . . . . . . . .  10
     3.7.  Payload-based Filtering . . . . . . . . . . . . . . . . .  10
     3.8.  Reuse the ACLs Content Across Several Devices . . . . . .  10
   4.  Overall Module Structure  . . . . . . . . . . . . . . . . . .  10
     4.1.  Enhanced ACL  . . . . . . . . . . . . . . . . . . . . . .  11
     4.2.  Defined sets  . . . . . . . . . . . . . . . . . . . . . .  13
     4.3.  TCP Flags Handling  . . . . . . . . . . . . . . . . . . .  14
     4.4.  Fragments Handling  . . . . . . . . . . . . . . . . . . .  14
     4.5.  Rate-Limit Traffic  . . . . . . . . . . . . . . . . . . .  19
     4.6.  ISID Filter . . . . . . . . . . . . . . . . . . . . . . .  19
     4.7.  VLAN Filter . . . . . . . . . . . . . . . . . . . . . . .  20
   5.  YANG Modules  . . . . . . . . . . . . . . . . . . . . . . . .  21
     5.1.  Enhanced ACL  . . . . . . . . . . . . . . . . . . . . . .  21
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .  38
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  39
     7.1.  URI Registration  . . . . . . . . . . . . . . . . . . . .  39
     7.2.  YANG Module Name Registration . . . . . . . . . . . . . .  39
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  40
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  40
     8.2.  Informative References  . . . . . . . . . . . . . . . . .  41
   Appendix A.  XLTS Template to Generate The ICMP Type
           IANA-Maintained Module  . . . . . . . . . . . . . . . . .  41

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   Appendix B.  Initial Version of the The ICMP Type IANA-Maintained
           Module  . . . . . . . . . . . . . . . . . . . . . . . . .  43
   Appendix C.  Acknowledgements . . . . . . . . . . . . . . . . . .  50
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  50

1.  Introduction

   [RFC8519] defines Access Control Lists (ACLs) as a user-ordered set
   of filtering rules.  The model targets the configuration of the
   filtering behavior of a device.  However, the model structure, as
   defined in [RFC8519], suffers from a set of limitations.  This
   document describes these limitations and proposes an enhanced ACL
   structure.  The YANG module in this document is solely based on
   augmentations to the ACL YANG module defined in [RFC8519].

   The motivation of such enhanced ACL structure is discussed in detail
   in Section 3.

   When managing ACLs, it is common for network operators to group match
   elements in pre-defined sets.  The consolidation into group matches
   allows for reducing the number of rules, especially in large scale
   networks.  If, for example, it is needed to find a match against 100
   IP addresses (or prefixes), a single rule will suffice rather than
   creating individual Access Control Entries (ACEs) for each IP address
   (or prefix).  In doing so, implementations would optimize the
   performance of matching lists vs multiple rules matching.

   The enhanced ACL structure is also meant to facilitate the management
   of network operators.  Instead of entering the IP address or port
   number literals, using user-named lists decouples the creation of the
   rule from the management of the sets.  Hence, it is possible to
   remove/add entries to the list without redefining the (parent) ACL
   rule.

   In addition, the notion of Access Control List (ACL) and defined sets
   is generalized so that it is not device-specific as per [RFC8519].
   ACLs and defined sets may be defined at network / administrative
   domain level and associated to devices.  This approach facilitates
   the reusability across multiple network elements.  For example,
   managing the IP prefix sets from a network level makes it easier to
   maintain by the security groups.

   Network operators maintain sets of IP prefixes that are related to
   each other, e.g., deny-lists or accept-lists that are associated with
   those provided by a VPN customer.  These lists are maintained and
   manipulated by security expert teams.

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   Note that ACLs are used locally in devices but are triggered by other
   tools such as DDoS mitigation [RFC9132] or BGP Flow Spec [RFC8955]
   [RFC8956].  Therefore, supporting means to easily map to the
   filtering rules conveyed in messages triggered by these tools is
   valuable from a network operation standpoint.

   The document also defines an IANA-maintained module for ICMP types.
   The design of the module adheres with the recommendations in
   [I-D.boucadair-netmod-iana-registries].  A template to generate the
   module is available at Appendix A.  Readers should refer to the IANA
   website [REF_TBC] to retrieve the latest version of the module.  The
   module is provided in Appendix B for the users convenience, but that
   appendix will be removed from the final RFC.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

   The terminology for describing YANG modules is defined in [RFC7950].
   The meaning of the symbols in the tree diagrams is defined in
   [RFC8340].

   In addition to the terms defined in [RFC8519], this document makes
   use of the following term:

   Defined set: :Refers to reusable description of one or multiple
   information elements (e.g., IP address, IP prefix, port number, or
   ICMP type).

3.  Problem Statement & Gap Analysis

3.1.  Suboptimal Configuration: Lack of Support for Lists of Prefixes

   IP prefix-related data nodes, e.g., "destination-ipv4-network" or
   "destination-ipv6-network", do not support handling a list of IP
   prefixes, which may then lead to having to support large numbers of
   ACL entries in a configuration file.

   The same issue is encountered when ACLs have to be in place to
   mitigate DDoS attacks that involve a set of sources (e.g.,
   [RFC9132]).  The situation is even worse when both a list of sources
   and destination prefixes are involved in the filtering.

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   Figure 1 shows an example of the required ACL configuration for
   filtering traffic from two prefixes.

   {
     "ietf-access-control-list:acls": {
       "acl": [
         {
           "name": "first-prefix",
           "type": "ipv6-acl-type",
           "aces": {
             "ace": [
               {
                 "name": "my-test-ace",
                 "matches": {
                   "ipv6": {
                     "destination-ipv6-network":
                       "2001:db8:6401:1::/64",
                     "source-ipv6-network":
                       "2001:db8:1234::/96",
                     "protocol": 17,
                     "flow-label": 10000
                   },
                   "udp": {
                     "source-port": {
                       "operator": "lte",
                       "port": 80
                     },
                     "destination-port": {
                       "operator": "neq",
                       "port": 1010
                     }
                   }
                 },
                 "actions": {
                   "forwarding": "accept"
                 }
               }
             ]
           }
         },
         {
           "name": "second-prefix",
           "type": "ipv6-acl-type",
           "aces": {
             "ace": [
               {
                 "name": "my-test-ace",
                 "matches": {

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                   "ipv6": {
                     "destination-ipv6-network":
                       "2001:db8:6401:c::/64",
                     "source-ipv6-network":
                       "2001:db8:1234::/96",
                     "protocol": 17,
                     "flow-label": 10000
                   },
                   "udp": {
                     "source-port": {
                       "operator": "lte",
                       "port": 80
                     },
                     "destination-port": {
                       "operator": "neq",
                       "port": 1010
                     }
                   }
                 },
                 "actions": {
                   "forwarding": "accept"
                 }
               }
             ]
           }
         }
       ]
     }
   }

      Figure 1: Example Illustrating Sub-optimal Use of the ACL Model
                     with a Prefix List (Message Body)

   Such a configuration is suboptimal for both:

   *  Network controllers that need to manipulate large files.  All or a
      subset for this configuration will need to be passed to the
      underlying network devices.

   *  Devices may receive such a configuration and thus will need to
      maintain it locally.

   Figure 2 depicts an example of an optimized structure:

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   {
     "ietf-access-control-list:acls": {
       "acl": [
         {
           "name": "prefix-list-support",
           "type": "ipv6-acl-type",
           "aces": {
             "ace": [
               {
                 "name": "my-test-ace",
                 "matches": {
                   "ipv6": {
                     "destination-ipv6-network": [
                       "2001:db8:6401:1::/64",
                       "2001:db8:6401:c::/64"
                     ],
                     "source-ipv6-network":
                       "2001:db8:1234::/96",
                     "protocol": 17,
                     "flow-label": 10000
                   },
                   "udp": {
                     "source-port": {
                       "operator": "lte",
                       "port": 80
                     },
                     "destination-port": {
                       "operator": "neq",
                       "port": 1010
                     }
                   }
                 },
                 "actions": {
                   "forwarding": "accept"
                 }
               }
             ]
           }
         }
       ]
     }
   }

      Figure 2: Example Illustrating Optimal Use of the ACL Model in a
                       Network Context (Message Body)

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3.2.  Manageability: Impossibility to Use Aliases or Defined Sets

   The same approach as the one discussed for IP prefixes can be
   generalized by introducing the concept of "aliases" or "defined
   sets".

   The defined sets are reusable definitions across several ACLs.  Each
   category is modelled in YANG as a list of parameters related to the
   class it represents.  The following sets can be considered:

   *  Prefix sets: Used to create lists of IPv4 or IPv6 prefixes.

   *  Protocol sets: Used to create a list of protocols.

   *  Port number sets: Used to create lists of TCP or UDP port values
      (or any other transport protocol that makes uses of port numbers).
      The identity of the protocols is identified by the protocol set,
      if present.  Otherwise, a set applies to any protocol.

   *  ICMP sets: Uses to create lists of ICMP-based filters.  This
      applies only when the protocol is set to ICMP or ICMPv6.

   A candidate structure is shown in Figure 3:

        +--rw defined-sets
        |  +--rw prefix-sets
        |  |  +--rw prefix-set* [name]
        |  |     +--rw name        string
        |  |     +--rw ip-prefix*   inet:ip-prefix
        |  +--rw port-sets
        |  |  +--rw port-set* [name]
        |  |     +--rw name    string
        |  |     +--rw port*   inet:port-number
        |  +--rw protocol-sets
        |  |  +--rw protocol-set* [name]
        |  |     +--rw name             string
        |  |     +--rw protocol-name*   identityref
        |  +--rw icmp-type-sets
        |     +--rw icmp-type-set* [name]
        |        +--rw name     string
        |        +--rw types* [type]
        |           +--rw type              uint8
        |           +--rw code?             uint8
        |           +--rw rest-of-header?   binary

                     Figure 3: Examples of Defined Sets

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   Aliases may also be considered to manage resources that are
   identified by a combination of various parameters as shown in the
   candidate tree in Figure 4.  Note that some aliases can be provided
   by decomposing them into separate sets.

           |  +--rw aliases
           |  |  +--rw alias* [name]
           |  |     +--rw name                 string
           |  |     +--rw prefix*       inet:ip-prefix
           |  |     +--rw port-range* [lower-port]
           |  |     |  +--rw lower-port    inet:port-number
           |  |     |  +--rw upper-port?   inet:port-number
           |  |     +--rw protocol*     uint8
           |  |     +--rw fqdn*         inet:domain-name
           |  |     +--rw uri*          inet:uri

                       Figure 4: Examples of Aliases

3.3.  Bind ACLs to Devices, Not Only Interfaces

   In the context of network management, an ACL may be enforced in many
   network locations.  As such, the ACL module should allow for binding
   an ACL to multiple devices, not only (abstract) interfaces.

   The ACL name must, thus, be unique at the scale of the network, but
   the same name may be used in many devices when enforcing node-
   specific ACLs.

3.4.  Partial or Lack of IPv4/IPv6 Fragment Handling

   [RFC8519] does not support fragment handling for IPv6 but offers a
   partial support for IPv4 through the use of 'flags'.  Nevertheless,
   the use of 'flags' is problematic since it does not allow a bitmask
   to be defined.  For example, setting other bits not covered by the
   'flags' filtering clause in a packet will allow that packet to get
   through (because it won't match the ACE).

   Defining a new IPv4/IPv6 matching field called 'fragment' is thus
   required to efficiently handle fragment-related filtering rules.

3.5.  Suboptimal TCP Flags Handling

   [RFC8519] supports including flags in the TCP match fields, however
   that structure does not support matching operations as those
   supported in BGP Flow Spec.  Defining this field to be defined as a
   flag bitmask together with a set of operations is meant to
   efficiently handle TCP flags filtering rules.

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3.6.  Rate-Limit Action

   [RFC8519] specifies that forwarding actions can be 'accept' (i.e.,
   accept matching traffic), 'drop' (i.e., drop matching traffic without
   sending any ICMP error message), or 'reject' (i.e., drop matching
   traffic and send an ICMP error message to the source).  However,
   there are situations where the matching traffic can be accepted, but
   with a rate-limit policy.  This capability is not supported by
   [RFC8519].

3.7.  Payload-based Filtering

   Some transport protocols use existing protocols (e.g., TCP or UDP) as
   substrate.  The match criteria for such protocols may rely upon the
   'protocol' under 'l3', TCP/UDP match criteria, part of the TCP/UDP
   payload, or a combination thereof.  [RFC8519] does not support
   matching based on the payload.

   Likewise, the current version of the ACL model does not support
   filtering of encapsulated traffic.

3.8.  Reuse the ACLs Content Across Several Devices

   Having a global network view of the ACLs is highly valuable for
   service providers.  An ACL could be defined and applied based on the
   network topology hierarchy.  So, an ACL can be defined at the network
   level and, then, that same ACL can be used (or referenced to) in
   several devices (including termination points) within the same
   network.

   This network/device ACLs differentiation introduces several new
   requirements, e.g.:

   *  An ACL name can be used at both network and device levels.

   *  An ACL content updated at the network level should imply a
      transaction that updates the relevant content in all the nodes
      using this ACL.

   *  ACLs defined at the device level have a local meaning for the
      specific node.

   *  A device can be associated with a router, a VRF, a logical system,
      or a virtual node.  ACLs can be applied in physical and logical
      infrastructure.

4.  Overall Module Structure

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4.1.  Enhanced ACL

   Figure 5 shows the full enhanced ACL tree:

   module: ietf-acl-enh
     +--rw defined-sets
     |  +--rw ipv4-prefix-sets
     |  |  +--rw prefix-set* [name]
     |  |     +--rw name           string
     |  |     +--rw description?   string
     |  |     +--rw prefix*        inet:ipv4-prefix
     |  +--rw ipv6-prefix-sets
     |  |  +--rw prefix-set* [name]
     |  |     +--rw name           string
     |  |     +--rw description?   string
     |  |     +--rw prefix*        inet:ipv6-prefix
     |  +--rw port-sets
     |  |  +--rw port-set* [name]
     |  |     +--rw name    string
     |  |     +--rw port* [id]
     |  |        +--rw id                              string
     |  |        +--rw (port)?
     |  |           +--:(port-range-or-operator)
     |  |              +--rw port-range-or-operator
     |  |                 +--rw (port-range-or-operator)?
     |  |                    +--:(range)
     |  |                    |  +--rw lower-port    inet:port-number
     |  |                    |  +--rw upper-port    inet:port-number
     |  |                    +--:(operator)
     |  |                       +--rw operator?     operator
     |  |                       +--rw port          inet:port-number
     |  +--rw protocol-sets
     |  |  +--rw protocol-set* [name]
     |  |     +--rw name        string
     |  |     +--rw protocol*   union
     |  +--rw icmp-type-sets
     |     +--rw icmp-type-set* [name]
     |        +--rw name     string
     |        +--rw types* [type]
     |           +--rw type              uint8
     |           +--rw code?             uint8
     |           +--rw rest-of-header?   binary
     +--rw aliases
        +--rw alias* [name]
           +--rw name          string
           +--rw prefix*       inet:ip-prefix
           +--rw port-range* [lower-port]
           |  +--rw lower-port    inet:port-number

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           |  +--rw upper-port?   inet:port-number
           +--rw protocol*     uint8
           +--rw fqdn*         inet:domain-name
           +--rw uri*          inet:uri

     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches:
       +--rw (payload)?
          +--:(prefix-pattern)
             +--rw prefix-pattern {match-on-payload}?
                +--rw offset?       identityref
                +--rw offset-end?   uint64
                +--rw operator?     operator
                +--rw prefix?       binary
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l2:
       +--rw vlan-filter {match-on-vlan-filter}?
          +--rw frame-type?         string
          +--rw (vlan-type)?
             +--:(range)
             |  +--rw lower-vlan    uint16
             |  +--rw upper-vlan    uint16
             +--:(operator)
                +--rw operator?     packet-fields:operator
                +--rw vlan*         uint16
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l2:
       +--rw isid-filter {match-on-isid-filter}?
          +--rw (isid-type)?
             +--:(range)
             |  +--rw lower-isid    uint16
             |  +--rw upper-isid    uint16
             +--:(operator)
                +--rw operator?     packet-fields:operator
                +--rw isid*         uint16
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l3
               /acl:ipv4:
       +--rw ipv4-fragment
       |  +--rw operator?   operator
       |  +--rw type?       fragment-type
       +--rw source-ipv4-prefix-list?        ipv4-prefix-set-ref
       +--rw destination-ipv4-prefix-list?   ipv4-prefix-set-ref
       +--rw next-header-set?                protocol-set-ref
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l3
               /acl:ipv6:
       +--rw ipv6-fragment
       |  +--rw operator?   operator
       |  +--rw type?       fragment-type
       +--rw source-ipv6-prefix-list?        ipv6-prefix-set-ref
       +--rw destination-ipv6-prefix-list?   ipv6-prefix-set-ref
       +--rw protocol-set?                   protocol-set-ref

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     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l4
               /acl:tcp:
       +--rw flags-bitmask
       |  +--rw (mode)?
       |     +--:(explicit)
       |     |  +--rw operator?            operator
       |     |  +--rw explicit-tcp-flag*   identityref
       |     +--:(builtin)
       |        +--rw bitmask?             uint16
       +--rw source-tcp-port-set?        port-set-ref
       +--rw destination-tcp-port-set?   port-set-ref
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l4
               /acl:udp:
       +--rw source-udp-port-set?        port-set-ref
       +--rw destination-udp-port-set?   port-set-ref
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches/acl:l4
               /acl:icmp:
       +--rw icmp-set?   icmp-type-set-ref
     augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:actions:
       +--rw rate-limit?   decimal64

                        Figure 5: Enhanced ACL tree

4.2.  Defined sets

   The augmented ACL structure includes several containers to manage
   reusable sets of elements that can be matched in an ACL entry.  Each
   set is uniquely identified by a name, and can be called from the
   relevant entry.  The following sets are defined:

   *  IPv4 prefix set: It contains a list of IPv4 prefixes.  A match
      will be considered if the IP address (source or destination,
      depending on the ACL entry) is contained in any of the prefixes.

   *  IPv6 prefix set: It contains a list of IPv6 prefixes.  A match
      will be considered if the IP address (source or destination,
      depending on the ACL entry) is contained in any of the prefixes.

   *  Port sets: It contains a list of port numbers to be used in TCP /
      UDP entries.  The ports can be individual port numbers, a range of
      ports, and an operation.

   *  Protocol sets: It contains a list of protocol values.  Each
      protocol can be identified either by a number (e.g., 17) or a name
      (e.g., UDP).

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   *  ICMP sets: It contains a list of ICMP types, each of them
      identified by a type value, optionally the code and the rest of
      the header.

4.3.  TCP Flags Handling

   The augmented ACL structure includes a new leaf 'flags-bitmask' to
   better handle flags.

   Clients that support both 'flags-bitmask' and 'flags' matching fields
   MUST NOT set these fields in the same request.

   Figure 6 shows an example of a request to install a filter to discard
   incoming TCP messages having all flags unset.

     {
        "ietf-access-control-list:acls": {
          "acl": [{
            "name": "tcp-flags-example",
            "aces": {
              "ace": [{
                "name": "null-attack",
                "matches": {
                  "tcp": {
                    "acl-enh:flags-bitmask": {
                      "operator": "not any",
                      "bitmask": 4095
                    }
                  }
                },
                "actions": {
                  "forwarding": "drop"
                }
              }]
            }
          }]
        }
      }

     Figure 6: Example to Deny TCP Null Attack Messages (Request Body)

4.4.  Fragments Handling

   The augmented ACL structure includes a new leaf 'fragment' to better
   handle fragments.

   Clients that support both 'fragment' and 'flags' matching fields MUST
   NOT set these fields in the same request.

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   Figure 7 shows the content of a POST request to allow the traffic
   destined to 198.51.100.0/24 and UDP port number 53, but to drop all
   fragmented packets.  The following ACEs are defined (in this order):

   *  "drop-all-fragments" ACE: discards all fragments.

   *  "allow-dns-packets" ACE: accepts DNS packets destined to
      198.51.100.0/24.

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   {
        "ietf-access-control-list:acls": {
          "acl": [
            {
              "name": "dns-fragments",
              "type": "ipv4-acl-type",
              "aces": {
                "ace": [
                  {
                    "name": "drop-all-fragments",
                    "matches": {
                      "ipv4": {
                        "acl-enh:ipv4-fragment": {
                          "operator": "match",
                          "type": "isf"
                        }
                      }
                    },
                    "actions": {
                      "forwarding": "drop"
                    }
                  },
                  {
                    "name": "allow-dns-packets",
                    "matches": {
                      "ipv4": {
                        "destination-ipv4-network": "198.51.100.0/24"
                      },
                      "udp": {
                        "destination-port": {
                          "operator": "eq",
                          "port": 53
                        }
                      },
                      "actions": {
                        "forwarding": "accept"
                      }
                    }
                  }
                ]
              }
            }
          ]
        }
      }

         Figure 7: Example Illustrating Candidate Filtering of IPv4
                     Fragmented Packets (Message Body)

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   Figure 8 shows an example of the body of a POST request to allow the
   traffic destined to 2001:db8::/32 and UDP port number 53, but to drop
   all fragmented packets.  The following ACEs are defined (in this
   order):

   *  "drop-all-fragments" ACE: discards all fragments (including atomic
      fragments).  That is, IPv6 packets that include a Fragment header
      (44) are dropped.

   *  "allow-dns-packets" ACE: accepts DNS packets destined to
      2001:db8::/32.

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       {
        "ietf-access-control-list:acls": {
          "acl": [
            {
              "name": "dns-fragments",
              "type": "ipv6-acl-type",
              "aces": {
                "ace": [
                  {
                    "name": "drop-all-fragments",
                    "matches": {
                      "ipv6": {
                        "acl-enh:ipv6-fragment": {
                          "operator": "match",
                          "type": "isf"
                        }
                      }
                    },
                    "actions": {
                      "forwarding": "drop"
                    }
                  },
                  {
                    "name": "allow-dns-packets",
                    "matches": {
                      "ipv6": {
                        "destination-ipv6-network": "2001:db8::/32"
                      },
                      "udp": {
                        "destination-port": {
                          "operator": "eq",
                          "port": 53
                        }
                      }
                    },
                    "actions": {
                      "forwarding": "accept"
                    }
                  }
                ]
              }
            }
          ]
        }
      }

         Figure 8: Example Illustrating Candidate Filtering of IPv6
                     Fragmented Packets (Message Body)

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4.5.  Rate-Limit Traffic

   In order to support rate-limiting (see Section 3.6), a new action
   called "rate-limit" is defined.  Figure 9 shows an ACL example to
   rate-limit incoming SYNs during a SYN flood attack.

     {
        "ietf-access-control-list:acls": {
          "acl": [{
            "name": "tcp-flags-example-with-rate-limit",
            "aces": {
              "ace": [{
                "name": "rate-limit-syn",
                "matches": {
                  "tcp": {
                    "acl-enh:flags-bitmask": {
                      "operator": "match",
                      "bitmask": 2
                    }
                  }
                },
                "actions": {
                  "forwarding": "accept",
                  "acl-enh:rate-limit": "20.00"
                }
              }]
            }
          }]
        }
      }

       Figure 9: Example Rate-Limit Incoming TCP SYNs (Message Body).

4.6.  ISID Filter

   Provider backbone bridging (PBB) was originally defined as Virtual
   Bridged Local Area Networks [IEEE802.1ah] standard.  However, instead
   of multiplexing VLANs, PBB duplicates the MAC layer of the customer
   frame and separates it from the provider domain, by encapsulating it
   in a 24 bit instance service identifier (I-SID).  This provides for
   more transparency between the customer network and the provider
   network.

   The I-component forms the customer or access facing interface or
   routing instance.  The I-component is responsible for mapping
   customer Ethernet traffic to the appropriate I-SID.  In the network
   is mandatory to configure the default service identifier.

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   Being able to filter by I-component Service identifier is a feature
   of the EVNP-PBB configuration.

   Figure 10 shows an ACL example to illustrate the ISID range
   filtering.

     {
       "ietf-acces-control-list:acls": {
             "acl": [
               {
                 "name": "test",
                 "aces": {
                   "ace": [
                     {
                       "name": "1",
                       "matches": {
                         "ietf-acl-enh:isid-filter": {
                           "lower-isid": 100,
                           "upper-isid": 200
                         }
                       },
                       "actions": {
                         "forwarding": "ietf-acces-control-list:accept"
                       }
                     }
                   ]
                 }
               }
             ]
           }
         }
       }
      }

               Figure 10: Example ISID Filter (Message Body)

4.7.  VLAN Filter

   Being able to filter all packets that are bridged within a VLAN or
   that are routed into or out of a bridge domain is part of the VPN
   control requirements derived of the EVPN definition done in
   [RFC7209].  So, all packets that are bridged within a VLAN or that
   are routed into or out of a VLAN can be captured, forwarded,
   translated or discarded based on the network policy applied.

   Figure 11 shows an ACL example to illustrate how to apply a VLAN
   range filter.

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     {
       "ietf-acces-control-list:acls": {
         "acl": [
           {
             "name": "VLAN_FILTER",
             "aces": {
               "ace": [
                 {
                   "name": "1",
                   "matches": {
                     "ietf-acl-enh:vlan-filter": {
                       "lower-vlan": 10,
                       "upper-vlan": 20
                     }
                   },
                   "actions": {
                     "forwarding": "ietf-acces-control-list:accept"
                   }
                 }
               ]
             }
           }
         ]
       }
      }

              Figure 11: Example of VLAN Filter (Message Body)

5.  YANG Modules

5.1.  Enhanced ACL

   <CODE BEGINS>
    file ietf-acl-enh@2022-10-24.yang

   module ietf-acl-enh {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:ietf-acl-enh";
     prefix acl-enh;

     import ietf-inet-types {
       prefix inet;
       reference
         "RFC 6991: Common YANG Data Types";
     }
     import ietf-access-control-list {
       prefix acl;
       reference

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         "RFC 8519: YANG Data Model for Network Access
                    Control Lists (ACLs), Section 4.1";
     }
     import ietf-packet-fields {
       prefix packet-fields;
       reference
         "RFC 8519: YANG Data Model for Network Access
                    Control Lists (ACLs), Section 4.2";
     }

     organization
       "IETF NETMOD Working Group";
     contact
       "WG Web:   https://datatracker.ietf.org/wg/netmod/
        WG List:  mailto:netmod@ietf.org

        Author:    Mohamed Boucadair
                  mailto:mohamed.boucadair@orange.com
        Author:    Samier Barguil
                  mailto:samier.barguilgiraldo.ext@telefonica.com
        Author:    Oscar Gonzalez de Dios
                  mailto:oscar.gonzalezdedios@telefonica.com";
     description
       "This module contains YANG definitions for enhanced ACLs.

        Copyright (c) 2023 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 Revised 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 2022-10-24 {
       description
         "Initial revision.";
       reference
         "RFC XXXX: Extensions to the Access Control Lists (ACLs)
                    YANG Model";
     }

     feature match-on-payload {
       description

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         "Match based on a pattern is supported.";
     }

     feature match-on-vlan-filter {
       description
         "Match based on a VLAN range of vlan list is supported.";
     }

     feature match-on-isid-filter {
       description
         "Match based on a ISID range of vlan list is supported.";
     }

     identity offset-type {
       description
         "Base identity for payload offset type.";
     }

     identity layer3 {
       base offset-type;
       description
         "The offset starts at the beginning of the IP header.";
     }

     identity layer4 {
       base offset-type;
       description
         "The offset start right after the IP header. This can be
          typically the beginning of transport header (e.g., TCP
          or UDP).";
     }

     identity payload {
       base offset-type;
       description
         "The offset start right after the end of the transport
          payload. For example, this represents the beginning of the
          TCP data right after any TCP options or the beginning of
          the UDP payload right after the UDP header.";
     }

     identity tcp-flag {
       description
         "Base Identity for the TCP Flags.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

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     identity ack {
       base tcp-flag;
       description
         "Acknowledgment TCP flag bit.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     identity syn {
       base tcp-flag;
       description
         "Synchronize sequence numbers.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     identity fin {
       base tcp-flag;
       description
         "No more data from the sender.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     identity urg {
       base tcp-flag;
       description
         "Urgent pointer TCP flag bit.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     identity psh {
       base tcp-flag;
       description
         "The Push function flag is similar to the URG flag and tells
          the receiver to process these packets as they are received
          instead of buffering them.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     identity rst {
       base tcp-flag;
       description
         "Reset TCP flag bit.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";

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     }

     identity ece {
       base tcp-flag;
       description
         "ECN-Echo TCP flag bit.";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     identity cwr {
       base tcp-flag;
       description
         "Congestion Window Reduced flag bit";
       reference
         "RFC 9293: Transmission Control Protocol (TCP), Section 3.1";
     }

     typedef operator {
       type bits {
         bit not {
           position 0;
           description
             "If set, logical negation of operation.";
         }
         bit match {
           position 1;
           description
             "Match bit.  This is a bitwise match operation defined as
              '(data & value) == value'.";
         }
         bit any {
           position 2;
           description
             "Any bit.  This is a match on any of the bits in  bitmask.
              It evaluates to 'true' if any of the bits in the value mask
              are set in the data,  i.e., '(data & value) != 0'.";
         }
       }
       description
         "Specifies how to apply the defined bitmask.
          'any' and 'match' bits must not be set simultaneously.";
     }

     typedef fragment-type {
       type bits {
         bit df {
           position 0;

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           description
             "Don't fragment bit for IPv4.
              Must be set to 0 when it appears in an IPv6 filter.";
         }
         bit isf {
           position 1;
           description
             "Is a fragment.";
         }
         bit ff {
           position 2;
           description
             "First fragment.";
         }
         bit lf {
           position 3;
           description
             "Last fragment.";
         }
       }
       description
         "Different fragment types to match against.";
     }

     typedef ipv4-prefix-set-ref {
       type leafref {
         path "/acl-enh:defined-sets/acl-enh:ipv4-prefix-sets"
            + "/acl-enh:prefix-set/acl-enh:name";
       }
       description
         "Defines a reference to an IPv4 prefix set.";
     }

     typedef ipv6-prefix-set-ref {
       type leafref {
         path "/acl-enh:defined-sets/acl-enh:ipv6-prefix-sets"
            + "/acl-enh:prefix-set/acl-enh:name";
       }
       description
         "Defines a reference to an IPv6 prefix set.";
     }

     typedef port-set-ref {
       type leafref {
         path "/acl-enh:defined-sets/acl-enh:port-sets"
            + "/acl-enh:port-set/acl-enh:name";
       }
       description

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         "Defines a reference to a port set.";
     }

     typedef protocol-set-ref {
       type leafref {
         path "/acl-enh:defined-sets/acl-enh:protocol-sets"
            + "/acl-enh:protocol-set/acl-enh:name";
       }
       description
         "Defines a reference to a protocol set.";
     }

     typedef icmp-type-set-ref {
       type leafref {
         path "/acl-enh:defined-sets/acl-enh:icmp-type-sets"
            + "/acl-enh:icmp-type-set/acl-enh:name";
       }
       description
         "Defines a reference to an ICMP type set.";
     }

     grouping tcp-flags {
       description
         "Operations on TCP flags.";
       choice mode {
         description
           "Choice of how flags are indicated.";
         case explicit {
           leaf operator {
             type operator;
             default "match";
             description
               "How to interpret the TCP flags.";
           }
           leaf-list explicit-tcp-flag {
             type identityref {
               base tcp-flag;
             }
             description
               "An explicit list of the TCP flags that are to be
                matched.";
           }
         }
         case builtin {
           leaf bitmask {
             type uint16;
             description
               "The bitmask matches the last 4 bits of byte 12 and 13 of

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                the TCP header.  For clarity, the 4 bits of byte 12
                corresponding to the TCP data offset field are not
                included in any matching.";
           }
         }
       }
     }

     grouping fragment-fields {
       description
         "Operations on fragment types.";
       leaf operator {
         type operator;
         default "match";
         description
           "How to interpret the fragment type.";
       }
       leaf type {
         type fragment-type;
         description
           "What fragment type to look for.";
       }
     }

     grouping payload {
       description
         "Operations on payload match.";
       leaf offset {
         type identityref {
           base offset-type;
         }
         description
           "Indicates the payload offset. This will indicate the position
            of the data in packet to use for the match.";
       }
       leaf offset-end {
         type uint64;
         units "bytes";
         description
           "Indicates the number of bytes, starting from the offset to
            cover when performing the prefix match.";
       }
       leaf operator {
         type operator;
         default "match";
         description
           "How to interpret the prefix match.";
       }

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       leaf prefix {
         type binary;
         description
           "The binary pattern to match against.";
       }
     }

     grouping alias {
       description
         "Specifies an alias.";
       leaf-list prefix {
         type inet:ip-prefix;
         description
           "IPv4 or IPv6 prefix of the alias.";
       }
       list port-range {
         key "lower-port";
         description
           "Port range.  When only lower-port is
            present, it represents a single port number.";
         leaf lower-port {
           type inet:port-number;
           mandatory true;
           description
             "Lower port number of the port range.";
         }
         leaf upper-port {
           type inet:port-number;
           must '. >= ../lower-port' {
             error-message
               "The upper-port number must be greater than
                or equal to the lower-port number.";
           }
           description
             "Upper port number of the port range.";
         }
       }
       leaf-list protocol {
         type uint8;
         description
           "Identifies the target protocol number.

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

            For example, 6 for TCP or 17 for UDP.";
       }
       leaf-list fqdn {

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

     augment "/acl:acls/acl:acl/acl:aces/acl:ace"
           + "/acl:matches" {
       description
         "Add a new match types.";
       choice payload {
         description
           "Match a prefix pattern.";
         container prefix-pattern {
           if-feature "match-on-payload";
           description
             "Rule to perform payload-based match.";
           uses payload;
         }
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l2" {
       description
         "Handle the augmentation of MAC VLAN Filter.";
       container vlan-filter {
         if-feature "match-on-vlan-filter";
         description
           "Indicates how to handle MAC VLANs.";
         leaf frame-type {
           type string;
           description
             "Entering the frame type allows the
              filter to match a specific type of frame format";
         }
         choice vlan-type {
           description
             "vlan definition from range or operator.";
           case range {
             leaf lower-vlan {
               type uint16;
               must '. <= ../upper-vlan' {

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                 error-message
                   "The lower-vlan must be less than or equal to
                    the upper-vlan.";
               }
               mandatory true;
               description
                 "Lower boundary for a vlan.";
             }
             leaf upper-vlan {
               type uint16;
               mandatory true;
               description
                 "Upper boundary for a vlan.";
             }
           }
           case operator {
             leaf operator {
               type packet-fields:operator;
               default "eq";
               description
                 "Operator to be applied on the vlan below.";
             }
             leaf-list vlan {
               type uint16;
               description
                 "vlan number along with the operator on which to
                  match.";
             }
           }
         }
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l2" {
       description
         "Handle the augmentation of ISID Filter.";
       container isid-filter {
         if-feature "match-on-isid-filter";
         description
           "Indicates how to handle ISID filters.
            The I-component is responsible for mapping customer
            Ethernet traffic to the appropriate ISID.";
         choice isid-type {
           description
             "ISID definition from range or operator.";
           case range {
             leaf lower-isid {

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               type uint16;
               must '. <= ../upper-isid' {
                 error-message
                   "The lower-vlan must be less than or equal to
                    the upper-isid.";
               }
               mandatory true;
               description
                 "Lower boundary for a ISID.";
             }
             leaf upper-isid {
               type uint16;
               mandatory true;
               description
                 "Upper boundary for a ISID.";
             }
           }
           case operator {
             leaf operator {
               type packet-fields:operator;
               default "eq";
               description
                 "Operator to be applied on the ISID below.";
             }
             leaf-list isid {
               type uint16;
               description
                 "ISID number along with the operator on which to
                  match.";
             }
           }
         }
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l3/acl:ipv4" {
       description
         "Handle non-initial and initial fragments for IPv4 packets.";
       container ipv4-fragment {
         description
           "Indicates how to handle IPv4 fragments.";
         uses fragment-fields;
       }
       leaf source-ipv4-prefix-list {
         type ipv4-prefix-set-ref;
         description
           "A reference to an IPv4 prefix list to match the source

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            address.";
       }
       leaf destination-ipv4-prefix-list {
         type ipv4-prefix-set-ref;
         description
           "A reference to a prefix list to match the destination
            address.";
       }
       leaf next-header-set {
         type protocol-set-ref;
         description
           "A reference to a protocol set to match the next-header
            field.";
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l3/acl:ipv6" {
       description
         "Handles non-initial and initial fragments for IPv6 packets.";
       container ipv6-fragment {
         description
           "Indicates how to handle IPv6 fragments.";
         uses fragment-fields;
       }
       leaf source-ipv6-prefix-list {
         type ipv6-prefix-set-ref;
         description
           "A reference to a prefix list to match the source address.";
       }
       leaf destination-ipv6-prefix-list {
         type ipv6-prefix-set-ref;
         description
           "A reference to a prefix list to match the destination
            address.";
       }
       leaf protocol-set {
         type protocol-set-ref;
         description
           "A reference to a protocol set to match the protocol field.";
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l4/acl:tcp" {
       description
         "Handles TCP flags and port sets.";
       container flags-bitmask {

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         description
           "Indicates how to handle TCP flags.";
         uses tcp-flags;
       }
       leaf source-tcp-port-set {
         type port-set-ref;
         description
           "A reference to a port set to match the source port.";
       }
       leaf destination-tcp-port-set {
         type port-set-ref;
         description
           "A reference to a port set to match the destination port.";
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l4/acl:udp" {
       description
         "Handle UDP port sets.";
       leaf source-udp-port-set {
         type port-set-ref;
         description
           "A reference to a port set to match the source port.";
       }
       leaf destination-udp-port-set {
         type port-set-ref;
         description
           "A reference to a port set to match the destination port.";
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:matches/acl:l4/acl:icmp" {
       description
         "Handle ICMP type sets.";
       leaf icmp-set {
         type icmp-type-set-ref;
         description
           "A reference to an ICMP type set to match the ICMP type
            field.";
       }
     }

     augment "/acl:acls/acl:acl/acl:aces"
           + "/acl:ace/acl:actions" {
       description
         "Rate-limit action.";

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       leaf rate-limit {
         when "../acl:forwarding = 'acl:accept'" {
           description
             "Rate-limit valid only when accept action is used.";
         }
         type decimal64 {
           fraction-digits 2;
         }
         units "bytes per second";
         description
           "Indicates a rate-limit for the matched traffic.";
       }
     }

     container defined-sets {
       description
         "Predefined sets of attributes used in policy match
          statements.";
       container ipv4-prefix-sets {
         description
           "Data definitions for a list of IPv4 or IPv6
            prefixes which are matched as part of a policy.";
         list prefix-set {
           key "name";
           description
             "List of the defined prefix sets.";
           leaf name {
             type string;
             description
               "Name of the prefix set -- this is used as a label to
                reference the set in match conditions.";
           }
           leaf description {
             type string;
             description
               "Defined Set description.";
           }
           leaf-list prefix {
             type inet:ipv4-prefix;
             description
               "List of IPv4 prefixes to be used in match
                conditions.";
           }
         }
       }
       container ipv6-prefix-sets {
         description
           "Data definitions for a list of IPv6 prefixes which are

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            matched as part of a policy.";
         list prefix-set {
           key "name";
           description
             "List of the defined prefix sets.";
           leaf name {
             type string;
             description
               "Name of the prefix set -- this is used as a label to
                reference the set in match conditions.";
           }
           leaf description {
             type string;
             description
               "A textual description of the prefix list.";
           }
           leaf-list prefix {
             type inet:ipv6-prefix;
             description
               "List of IPv6 prefixes to be used in match conditions.";
           }
         }
       }
       container port-sets {
         description
           "Data definitions for a list of ports which can
            be matched in policies.";
         list port-set {
           key "name";
           description
             "List of port set definitions.";
           leaf name {
             type string;
             description
               "Name of the port set -- this is used as a label to
                reference the set in match conditions.";
           }
           list port {
             key "id";
             description
               "Port numbers along with the operator on which to
                match.";
             leaf id {
               type string;
               description
                 "Identifier of the list of port numbers.";
             }
             choice port {

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               description
                 "Choice of specifying the port number or referring to a
                  group of port numbers.";
               container port-range-or-operator {
                 description
                   "Indicates a set of ports.";
                 uses packet-fields:port-range-or-operator;
               }
             }
           }
         }
       }
       container protocol-sets {
         description
           "Data definitions for a list of protocols which can be matched
            in policies.";
         list protocol-set {
           key "name";
           description
             "List of protocol set definitions.";
           leaf name {
             type string;
             description
               "Name of the protocols set -- this is used as a label to
                reference the set in match conditions.";
           }
           leaf-list protocol {
             type union {
               type uint8;
               type string;
             }
             description
               "Value of the protocol set.";
             //Check if we can reuse an IANA-maintained module
           }
         }
       }
       container icmp-type-sets {
         description
           "Data definitions for a list of ICMP types which can be
            matched in policies.";
         list icmp-type-set {
           key "name";
           description
             "List of ICMP type set definitions.";
           leaf name {
             type string;
             description

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               "Name of the ICMP type set -- this is used as a label to
                reference the set in match conditions.";
           }
           list types {
             key "type";
             description
               "Includes a list of ICMP types.";
             uses packet-fields:acl-icmp-header-fields;
           }
         }
       }
     }
     container aliases {
       description
         "Top-levl container for aliases.";
       list alias {
         key "name";
         description
           "List of aliases.";
         leaf name {
           type string;
           description
             "The name of the alias.";
         }
         uses alias;
       }
     }
   }
   <CODE ENDS>

6.  Security Considerations

   The YANG modules specified in this document define a schema for data
   that is designed to be accessed via network management protocol such
   as NETCONF [RFC6241] or RESTCONF [RFC8040].  The lowest NETCONF layer
   is the secure transport layer, and the mandatory-to-implement secure
   transport is Secure Shell (SSH) [RFC6242].  The lowest RESTCONF layer
   is HTTPS, and the mandatory-to-implement secure transport is TLS
   [RFC8446].

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

   There are a number of data nodes defined in this YANG module that are
   writable/creatable/deletable (i.e., config true, which is the
   default).  These data nodes may be considered sensitive or vulnerable

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   in some network environments.  Write operations (e.g., edit-config)
   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:

   *  TBC

   Some of the readable data nodes in this YANG module may be considered
   sensitive or vulnerable in some network environments.  It is thus
   important to control read access (e.g., via get, get-config, or
   notification) to these data nodes.  These are the subtrees and data
   nodes and their sensitivity/vulnerability:

   *  TBC

7.  IANA Considerations

7.1.  URI Registration

   This document requests IANA to register the following URIs in the
   "ns" subregistry within the "IETF XML Registry" [RFC3688]:

            URI: urn:ietf:params:xml:ns:yang:ietf-acl-enh
            Registrant Contact: The IESG.
            XML: N/A; the requested URI is an XML namespace.

            URI: urn:ietf:params:xml:ns:yang:iana-icmp-types
            Registrant Contact: The IESG.
            XML: N/A; the requested URI is an XML namespace.

7.2.  YANG Module Name Registration

   This document requests IANA to register the following YANG modules in
   the "YANG Module Names" subregistry [RFC6020] within the "YANG
   Parameters" registry.

            name: ietf-acl-enh
            namespace: urn:ietf:params:xml:ns:yang:ietf-acl-enh
            maintained by IANA: N
            prefix: acl-enh
            reference: RFC XXXX

            name: ietf-icmp-types
            namespace: urn:ietf:params:xml:ns:yang:iana-icmp-types
            maintained by IANA: Y
            prefix: iana-icmp-types
            reference: RFC XXXX

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8.  References

8.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/rfc/rfc2119>.

   [RFC3688]  Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
              DOI 10.17487/RFC3688, January 2004,
              <https://www.rfc-editor.org/rfc/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/rfc/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/rfc/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/rfc/rfc6242>.

   [RFC7209]  Sajassi, A., Aggarwal, R., Uttaro, J., Bitar, N.,
              Henderickx, W., and A. Isaac, "Requirements for Ethernet
              VPN (EVPN)", RFC 7209, DOI 10.17487/RFC7209, May 2014,
              <https://www.rfc-editor.org/rfc/rfc7209>.

   [RFC7950]  Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
              RFC 7950, DOI 10.17487/RFC7950, August 2016,
              <https://www.rfc-editor.org/rfc/rfc7950>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration
              Access Control Model", STD 91, RFC 8341,
              DOI 10.17487/RFC8341, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8341>.

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   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol
              Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
              <https://www.rfc-editor.org/rfc/rfc8446>.

   [RFC8519]  Jethanandani, M., Agarwal, S., Huang, L., and D. Blair,
              "YANG Data Model for Network Access Control Lists (ACLs)",
              RFC 8519, DOI 10.17487/RFC8519, March 2019,
              <https://www.rfc-editor.org/rfc/rfc8519>.

   [RFC8956]  Loibl, C., Ed., Raszuk, R., Ed., and S. Hares, Ed.,
              "Dissemination of Flow Specification Rules for IPv6",
              RFC 8956, DOI 10.17487/RFC8956, December 2020,
              <https://www.rfc-editor.org/rfc/rfc8956>.

8.2.  Informative References

   [I-D.boucadair-netmod-iana-registries]
              Boucadair, M., "Recommendations for Creating IANA-
              Maintained YANG Modules", Work in Progress, Internet-
              Draft, draft-boucadair-netmod-iana-registries-07, 20
              January 2023, <https://datatracker.ietf.org/doc/html/
              draft-boucadair-netmod-iana-registries-07>.

   [RFC8340]  Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
              BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
              <https://www.rfc-editor.org/rfc/rfc8340>.

   [RFC8955]  Loibl, C., Hares, S., Raszuk, R., McPherson, D., and M.
              Bacher, "Dissemination of Flow Specification Rules",
              RFC 8955, DOI 10.17487/RFC8955, December 2020,
              <https://www.rfc-editor.org/rfc/rfc8955>.

   [RFC9132]  Boucadair, M., Ed., Shallow, J., and T. Reddy.K,
              "Distributed Denial-of-Service Open Threat Signaling
              (DOTS) Signal Channel Specification", RFC 9132,
              DOI 10.17487/RFC9132, September 2021,
              <https://www.rfc-editor.org/rfc/rfc9132>.

Appendix A.  XLTS Template to Generate The ICMP Type IANA-Maintained
             Module

   <CODE BEGINS>
   <?xml version="1.0" encoding="utf-8"?>
   <stylesheet
       xmlns="http://www.w3.org/1999/XSL/Transform"
       xmlns:html="http://www.w3.org/1999/xhtml"
       xmlns:iana="http://www.iana.org/assignments"
       xmlns:yin="urn:ietf:params:xml:ns:yang:yin:1"

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       version="1.0">
     <import href="../../../xslt/iana-yinx.xsl"/>
     <output method="xml" encoding="utf-8"/>
     <strip-space elements="*"/>

     <template match="iana:registry[@id='icmp-parameters-types']">
       <element name="yin:typedef">
         <attribute name="name">icmp-type-name</attribute>
         <element name="yin:type">
           <attribute name="name">enumeration</attribute>
           <apply-templates
               select="iana:record[not(iana:description = 'Unassigned' or
                       starts-with(iana:description, 'Reserved') or
                       starts-with(iana:description, 'RFC3692')) or
                       contains(iana:description, 'experimental')]"/>
         </element>
         <element name="yin:description">
           <element name="yin:text">
             This enumeration type defines mnemonic names and
             corresponding numeric values of ICMP types.
           </element>
         </element>
         <element name="yin:reference">
           <element name="yin:text">
             RFC 2708: IANA Allocation Guidelines For Values In
                       the Internet Protocol and Related Headers
           </element>
         </element>
       </element>
       <element name="yin:typedef">
         <attribute name="name">icmp-type</attribute>
         <element name="yin:type">
           <attribute name="name">union</attribute>
           <element name="yin:type">
             <attribute name="name">uint8/</attribute>
           </element>
           <element name="yin:type">
             <attribute name="name">icmp-type-name</attribute>
           </element>
         </element>
         <element name="yin:description">
           <element name="yin:text">
             This type allows reference to an ICMP type using either
             the assigned mnemonic name or numeric value.
           </element>
         </element>
       </element>
     </template>

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     <template match="iana:record">
       <call-template name="enum">
         <with-param name="id">
           <choose>
             <when test="contains(iana:description, '(Deprecated)')">
               <value-of select="translate(normalize-space(substring-before(iana:description,
                     '(Deprecated)')),' ','')"/>
             </when>
             <otherwise>
               <value-of select="translate(normalize-space(iana:description),' ','')"/>
             </otherwise>
           </choose>
         </with-param>
         <with-param name="deprecated"
                     select="contains(iana:description, '(Deprecated)')"/>
       </call-template>
     </template>

   </stylesheet>
   <CODE ENDS>

Appendix B.  Initial Version of the The ICMP Type IANA-Maintained Module

   <CODE BEGINS>
    file iana-icmp-types@2020-09-25.yang

   module iana-icmp-types {
     yang-version 1.1;
     namespace "urn:ietf:params:xml:ns:yang:iana-icmp-types";
     prefix iana-icmp-types;

     organization
       "Internet Assigned Numbers Authority (IANA)";

     contact
       "Internet Assigned Numbers Authority

        ICANN
        12025 Waterfront Drive, Suite 300
        Los Angeles, CA 90094

        Tel: +1 424 254 5300

        <mailto:iana@iana.org>";

     description
       "This YANG module translates IANA registry 'ICMP Type Numbers' to

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        YANG derived types.

        Copyright (c) 2023 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 Revised BSD License set
        forth in Section 4.c of the IETF Trust's Legal Provisions
        Relating to IETF Documents
        (https://trustee.ietf.org/license-info).

        This version of this YANG module was generated from the
        corresponding IANA registry using an XSLT stylesheet from the
        'iana-yang' project (https://github.com/llhotka/iana-yang).";

     reference
       "Internet Control Message Protocol (ICMP) Parameters
        (https://www.iana.org/assignments/icmp-parameters/)";

     revision 2020-09-25 {
       description
         "Current revision as of the revision date specified in the XML
          representation of the registry page.";
       reference
         "https://www.iana.org/assignments/icmp-parameters/icmp-parameters.xml";
     }

     /* Typedefs */

     typedef icmp-type-name {
       type enumeration {
         enum EchoReply {
           value 0;
           description
             "Echo Reply";
           reference
             "RFC 792";
         }
         enum DestinationUnreachable {
           value 3;
           description
             "Destination Unreachable";
           reference
             "RFC 792";
         }
         enum SourceQuench {
           value 4;

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           status deprecated;
           description
             "Source Quench (Deprecated)";
           reference
             "- RFC 792
              - RFC 6633";
         }
         enum Redirect {
           value 5;
           description
             "Redirect";
           reference
             "RFC 792";
         }
         enum AlternateHostAddress {
           value 6;
           status deprecated;
           description
             "Alternate Host Address (Deprecated)";
           reference
             "RFC 6918";
         }
         enum Echo {
           value 8;
           description
             "Echo";
           reference
             "RFC 792";
         }
         enum RouterAdvertisement {
           value 9;
           description
             "Router Advertisement";
           reference
             "RFC 1256";
         }
         enum RouterSolicitation {
           value 10;
           description
             "Router Solicitation";
           reference
             "RFC 1256";
         }
         enum TimeExceeded {
           value 11;
           description
             "Time Exceeded";
           reference

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             "RFC 792";
         }
         enum ParameterProblem {
           value 12;
           description
             "Parameter Problem";
           reference
             "RFC 792";
         }
         enum Timestamp {
           value 13;
           description
             "Timestamp";
           reference
             "RFC 792";
         }
         enum TimestampReply {
           value 14;
           description
             "Timestamp Reply";
           reference
             "RFC 792";
         }
         enum InformationRequest {
           value 15;
           status deprecated;
           description
             "Information Request (Deprecated)";
           reference
             "- RFC 792
              - RFC 6918";
         }
         enum InformationReply {
           value 16;
           status deprecated;
           description
             "Information Reply (Deprecated)";
           reference
             "- RFC 792
              - RFC 6918";
         }
         enum AddressMaskRequest {
           value 17;
           status deprecated;
           description
             "Address Mask Request (Deprecated)";
           reference
             "- RFC 950

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              - RFC 6918";
         }
         enum AddressMaskReply {
           value 18;
           status deprecated;
           description
             "Address Mask Reply (Deprecated)";
           reference
             "- RFC 950
              - RFC 6918";
         }
         enum Traceroute {
           value 30;
           status deprecated;
           description
             "Traceroute (Deprecated)";
           reference
             "- RFC 1393
              - RFC 6918";
         }
         enum DatagramConversionError {
           value 31;
           status deprecated;
           description
             "Datagram Conversion Error (Deprecated)";
           reference
             "- RFC 1475
              - RFC 6918";
         }
         enum MobileHostRedirect {
           value 32;
           status deprecated;
           description
             "Mobile Host Redirect (Deprecated)";
           reference
             "- David Johnson <>
              - RFC 6918";
         }
         enum IPv6Where-Are-You {
           value 33;
           status deprecated;
           description
             "IPv6 Where-Are-You (Deprecated)";
           reference
             "- Bill Simpson <mailto:Bill.Simpson&um.cc.umich.edu>
              - RFC 6918";
         }
         enum IPv6I-Am-Here {

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           value 34;
           status deprecated;
           description
             "IPv6 I-Am-Here (Deprecated)";
           reference
             "- Bill Simpson <mailto:Bill.Simpson&um.cc.umich.edu>
              - RFC 6918";
         }
         enum MobileRegistrationRequest {
           value 35;
           status deprecated;
           description
             "Mobile Registration Request (Deprecated)";
           reference
             "- Bill Simpson <mailto:Bill.Simpson&um.cc.umich.edu>
              - RFC 6918";
         }
         enum MobileRegistrationReply {
           value 36;
           status deprecated;
           description
             "Mobile Registration Reply (Deprecated)";
           reference
             "- Bill Simpson <mailto:Bill.Simpson&um.cc.umich.edu>
              - RFC 6918";
         }
         enum DomainNameRequest {
           value 37;
           status deprecated;
           description
             "Domain Name Request (Deprecated)";
           reference
             "- RFC 1788
              - RFC 6918";
         }
         enum DomainNameReply {
           value 38;
           status deprecated;
           description
             "Domain Name Reply (Deprecated)";
           reference
             "- RFC 1788
              - RFC 6918";
         }
         enum SKIP {
           value 39;
           status deprecated;
           description

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             "SKIP (Deprecated)";
           reference
             "- Tom Markson <mailto:markson&osmosys.incog.com>
              - RFC 6918";
         }
         enum Photuris {
           value 40;
           description
             "Photuris";
           reference
             "RFC 2521";
         }
         enum ICMPmessagesutilizedbyexperimentalmobilityprotocolssuchasSeamoby {
           value 41;
           description
             "ICMP messages utilized by experimental mobility protocols
              such as Seamoby";
           reference
             "RFC 4065";
         }
         enum ExtendedEchoRequest {
           value 42;
           description
             "Extended Echo Request";
           reference
             "RFC 8335";
         }
         enum ExtendedEchoReply {
           value 43;
           description
             "Extended Echo Reply";
           reference
             "RFC 8335";
         }
       }
       description
         "This enumeration type defines mnemonic names and corresponding
          numeric values of ICMP types.";
       reference
         "RFC 2708: IANA Allocation Guidelines For Values In the
          Internet Protocol and Related Headers";
     }

     typedef icmp-type {
       type union {
         type uint8;
         type icmp-type-name;
       }

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       description
         "This type allows reference to an ICMP type using either the
          assigned mnemonic name or numeric value.";
     }
   }
   <CODE ENDS>

Appendix C.  Acknowledgements

   Many thanks to Jon Shallow and Miguel Cros for the review and
   comments to the document, including prior to publishing the document.

   Thanks to Qiufang Ma and Victor Lopez for the comments and
   suggestions.

   The IANA-maintained model was generated using an XSLT stylesheet from
   the 'iana-yang' project (https://github.com/llhotka/iana-yang).

   This work is partially supported by the European Commission under
   Horizon 2020 Secured autonomic traffic management for a Tera of SDN
   flows (Teraflow) project (grant agreement number 101015857).

Authors' Addresses

   Oscar Gonzalez de Dios
   Telefonica
   Email: oscar.gonzalezdedios@telefonica.com

   Samier Barguil
   Telefonica
   Email: samier.barguilgiraldo.ext@telefonica.com

   Mohamed Boucadair
   Orange
   Email: mohamed.boucadair@orange.com

   Qin Wu
   Huawei
   Email: bill.wu@huawei.com

Dios, et al.            Expires 11 September 2023              [Page 50]