Internet-Draft Enhanced ACLs June 2023
Dios, et al. Expires 29 December 2023 [Page]
Workgroup:
netmod
Internet-Draft:
draft-ietf-netmod-acl-extensions-02
Published:
Intended Status:
Standards Track
Expires:
Authors:
O. G. D. Dios
Telefonica
S. Barguil
Telefonica
M. Boucadair
Orange
Q. Wu
Huawei

Extensions to the Access Control Lists (ACLs) YANG Model

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 29 December 2023.

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Table of Contents

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.

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.

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": {
                "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:

{
  "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)

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

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.

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.

3.9. Match MPLS Headers

The ACLs could be used to create rules to match MPLS fields on a packet.

4. Overall Module Structure

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
        |  +--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
    +--rw (alias)?
    |  +--rw alias-name*        alias-ref
    +--rw (mpls)?
       +--:(mpls-values)
          +--rw mpls-values {match-on-mpls}?
             +--rw traffic-class?       uint8
             +--rw label-position       identityref
             +--rw upper-label-range?   uint32
             +--rw lower-label-range?   uint32
             +--rw label-block-name     string
             +--rw ttl-value?           uint8
  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
  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).
  • 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.

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. 
{
     "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)

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. 
    {
     "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)

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.

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.

  {
    "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)

4.8. Match MPLS Headers

The ACL models can be used to create rules to match MPLS fields on a packet. The MPLS headers defined in [RFC3032] and [RFC5462] contains the following fields:

  • Traffic Class: 3 bits 'EXP' renamed to 'Traffic Class Field."
  • Label Value: A 20-bit field that carries the actual value of the MPLS Label.
  • TTL: An eight-bit field that is used to encode a time-to-live value.

The structure of the MPLS ACL subtree is shown in Figure 12:

  augment /acl:acls/acl:acl/acl:aces/acl:ace/acl:matches:
    ...
    +--rw (mpls)?
       +--:(mpls-values)
          +--rw mpls-values {match-on-mpls}?
             +--rw traffic-class?       uint8
             +--rw label-position       identityref
             +--rw upper-label-range?   uint32
             +--rw lower-label-range?   uint32
             +--rw label-block-name     string
             +--rw ttl-value?           uint8
Figure 12: MPLS Header Match Subtree

5. YANG Modules

5.1. Enhanced ACL

This model imports types from [RFC6991], [RFC8519], and [RFC8294].

<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
      "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";
  }

  import ietf-routing-types {
    prefix rt-types;
    reference
      "RFC 8294: Common YANG Data Types for the Routing Area";
    }

  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
      "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.";
  }

  feature match-on-alias {
    description
      "Match based on aliases.";
  }

  feature match-on-mpls {
    description
      "Match based on MPLS headers.";
  }

  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";
  }

  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";
  }

  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";
  }

  identity mpls-acl-type {
    base acl:acl-base;
    description
      "An ACL that matches on fields from the MPLS header.";
  }

  identity label-position {
    description
      "Base identity for deriving MPLS label position.";
  }

  identity top {
    base label-position;
    description
      "Top of the label stack.";
  }

  identity bottom {
    base label-position;
    description
      "Bottom of the label stack.";
  }

  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;
        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
      "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.";
  }

  typedef alias-ref {
    type leafref {
      path "/acl-enh:aliases/acl-enh:alias/acl-enh:name";
    }
    description
      "Defines a reference to an alias.";
  }

  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
             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 mpls-match-parameters-config {
  description
    "Parameters for the configuration of MPLS match rules.";

  leaf traffic-class {
    type uint8 {
      range "0..7";
    }
    description
      "The value of the MPLS traffic class (TC) bits,
       formerly known as the EXP bits.";
  }

  leaf label-position {
    type identityref {
      base label-position;
    }
    description
      "Position of the label";
  }

  leaf upper-label-range {
    type rt-types:mpls-label;
    description
      "Match MPLS label value on the MPLS header.
       The usage of this field indicated the upper
       range value in the top of the stack.
       This label value does not include the
       encodings of Traffic Class and TTL.";
     reference
       "RFC 3032: MPLS Label Stack Encoding";
  }

  leaf lower-label-range {
    type rt-types:mpls-label;
    description
      "Match MPLS label value on the MPLS header.
       The usage of this field indicated the lower
       range value in the top of the stack.
       This label value does not include the
       encodings of Traffic Class and TTL.";
     reference
       "RFC 3032: MPLS Label Stack Encoding";
  }

  leaf label-block-name {
    type string;
    description
    "Reference to a label block predefiend in the
     implementation.";
  }

  leaf ttl-value {
    type uint8;
    description
      "Time-to-live MPLS packet value match.";
    reference
      "RFC 3032: MPLS Label Stack Encoding";
    }
  }

  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.";
    }
    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 {
      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;
      }
    }
    choice alias {
      description
        "Match on aliases.";
      leaf-list alias-name {
        type alias-ref;
        description
          "A set of aliases.";
      }
    }
    choice mpls {
      container mpls-values {
        if-feature "match-on-mpls";
        uses mpls-match-parameters-config;
        description
          "Rule set that matches MPLS headers.";
      }
      description
        "Match MPLS headers, for example, label values";
    }
  }

  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' {
              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 {
            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
         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 {
      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.";
    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
         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 {
            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
            "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 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:

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:

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

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, , <https://www.rfc-editor.org/rfc/rfc2119>.
[RFC3032]
Rosen, E., Tappan, D., Fedorkow, G., Rekhter, Y., Farinacci, D., Li, T., and A. Conta, "MPLS Label Stack Encoding", RFC 3032, DOI 10.17487/RFC3032, , <https://www.rfc-editor.org/rfc/rfc3032>.
[RFC3688]
Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, DOI 10.17487/RFC3688, , <https://www.rfc-editor.org/rfc/rfc3688>.
[RFC5462]
Andersson, L. and R. Asati, "Multiprotocol Label Switching (MPLS) Label Stack Entry: "EXP" Field Renamed to "Traffic Class" Field", RFC 5462, DOI 10.17487/RFC5462, , <https://www.rfc-editor.org/rfc/rfc5462>.
[RFC6020]
Bjorklund, M., Ed., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, DOI 10.17487/RFC6020, , <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, , <https://www.rfc-editor.org/rfc/rfc6241>.
[RFC6242]
Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, , <https://www.rfc-editor.org/rfc/rfc6242>.
[RFC6991]
Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 6991, DOI 10.17487/RFC6991, , <https://www.rfc-editor.org/rfc/rfc6991>.
[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, , <https://www.rfc-editor.org/rfc/rfc7209>.
[RFC7950]
Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", RFC 7950, DOI 10.17487/RFC7950, , <https://www.rfc-editor.org/rfc/rfc7950>.
[RFC8040]
Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol", RFC 8040, DOI 10.17487/RFC8040, , <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, , <https://www.rfc-editor.org/rfc/rfc8174>.
[RFC8294]
Liu, X., Qu, Y., Lindem, A., Hopps, C., and L. Berger, "Common YANG Data Types for the Routing Area", RFC 8294, DOI 10.17487/RFC8294, , <https://www.rfc-editor.org/rfc/rfc8294>.
[RFC8341]
Bierman, A. and M. Bjorklund, "Network Configuration Access Control Model", STD 91, RFC 8341, DOI 10.17487/RFC8341, , <https://www.rfc-editor.org/rfc/rfc8341>.
[RFC8446]
Rescorla, E., "The Transport Layer Security (TLS) Protocol Version 1.3", RFC 8446, DOI 10.17487/RFC8446, , <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, , <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, , <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, , <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, , <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, , <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, , <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"
    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>

  <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
     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;
        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
          "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
           - 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 {
        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
          "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;
    }
    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
Samier Barguil
Telefonica
Mohamed Boucadair
Orange
Qin Wu
Huawei