NETMOD WG D. Bogdanovic
Internet-Draft Volta Networks
Intended status: Standards Track K. Sreenivasa
Expires: September 14, 2017 Cisco Systems
L. Huang
General Electric
D. Blair
Cisco Systems
March 13, 2017
Network Access Control List (ACL) YANG Data Model
draft-ietf-netmod-acl-model-10
Abstract
This document describes a data model of Access Control List (ACL)
basic building blocks.
Editorial Note (To be removed by RFC Editor)
This draft contains many placeholder values that need to be replaced
with finalized values at the time of publication. This note
summarizes all of the substitutions that are needed. Please note
that no other RFC Editor instructions are specified anywhere else in
this document.
Artwork in this document contains shorthand references to drafts in
progress. Please apply the following replacements
o "XXXX" --> the assigned RFC value for this draft.
o Revision date in model (Oct 12, 2016) needs to get updated with
the date the draft gets approved. The date also needs to get
reflected on the line with <CODE BEGINS>.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
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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 September 14, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Definitions and Acronyms . . . . . . . . . . . . . . . . 3
2. Problem Statement . . . . . . . . . . . . . . . . . . . . . . 4
3. Understanding ACL's Filters and Actions . . . . . . . . . . . 4
3.1. ACL Modules . . . . . . . . . . . . . . . . . . . . . . . 5
4. ACL YANG Models . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. IETF Access Control List module . . . . . . . . . . . . . 7
4.2. IETF Packet Fields module . . . . . . . . . . . . . . . . 12
4.3. An ACL Example . . . . . . . . . . . . . . . . . . . . . 16
4.4. Port Range Usage Example . . . . . . . . . . . . . . . . 16
5. Security Considerations . . . . . . . . . . . . . . . . . . . 17
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.1. Normative References . . . . . . . . . . . . . . . . . . 19
8.2. Informative References . . . . . . . . . . . . . . . . . 19
Appendix A. Extending ACL model examples . . . . . . . . . . . . 20
A.1. Example of extending existing model for route filtering . 20
A.2. A company proprietary module example . . . . . . . . . . 22
A.3. Example to augment model with mixed ACL type . . . . . . 30
A.4. Linux nftables . . . . . . . . . . . . . . . . . . . . . 30
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 31
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1. Introduction
Access Control List (ACL) is one of the basic elements to configure
device forwarding behavior. It is used in many networking concepts
such as Policy Based Routing, Firewalls etc.
An ACL is an ordered set of rules that is used to filter traffic on a
networking device. Each rule is represented by an Access Control
Entry (ACE).
Each ACE has a group of match criteria and a group of action
criteria.
The match criteria consist of a tuple of packet header match criteria
and can have metadata match criteria as well.
o Packet header matches apply to fields visible in the packet such
as address or class of service or port numbers.
o In case vendor suppors it, metadata matches apply to fields
associated with the packet but not in the packet header such as
input interface or overall packet length
The actions specify what to do with the packet when the matching
criteria is met. These actions are any operations that would apply
to the packet, such as counting, policing, or simply forwarding.The
list of potential actions is endless depending on the innovations of
the networked devices.
Access Control List is also widely knowns as ACL (pronounce as [ak-uh
l]) or Access List. In this document, Access Control List, ACL and
Access List are interchangeable.
The matching of filters and actions in an ACE/ACL are triggered only
after application/attachment of the ACL to an interface, VRF, vty/tty
session, QoS policy, routing protocols amongst various other config
attachment points. Once attached, it is used for filtering traffic
using the match cirteria in the ACE's and taking appropriate
action(s) that have been configured against that ACE. In order to
apply an ACL to any attachment point, vendors would have to augment
the ACL YANG model.
1.1. Definitions and Acronyms
ACE: Access Control Entry
ACL: Access Control List
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DSCP: Differentiated Services Code Point
ICMP: Internet Control Message Protocol
IP: Internet Protocol
IPv4: Internet Protocol version 4
IPv6: Internet Protocol version 6
MAC: Media Access Control
TCP: Transmission Control Protocol
2. Problem Statement
This document defines a YANG [RFC6020] data model for the
configuration of ACLs. It is very important that model can be easily
used by applications/attachments.
ACL implementations in every device may vary greatly in terms of the
filter constructs and actions that they support. Therefore this
draft proposes a model that can be augmented by standard extensions
and vendor proprietary models.
3. Understanding ACL's Filters and Actions
Although different vendors have different ACL data models, there is a
common understanding of what access control list (ACL) is. A network
system usually have a list of ACLs, and each ACL contains an ordered
list of rules, also known as access list entries - ACEs. Each ACE
has a group of match criteria and a group of action criteria. The
match criteria consist of packet header matching. It as also
possible for ACE to match on metadata, if supported by the vendor.
Packet header matching applies to fields visible in the packet such
as address or class of service or port numbers. Metadata matching
applies to fields associated with the packet, but not in the packet
header such as input interface, packet length, or source or
destination prefix length. The actions can be any sort of operation
from logging to rate limiting or dropping to simply forwarding.
Actions on the first matching ACE are applied with no processing of
subsequent ACEs. The model also includes a container to hold overall
operational state for each ACL and operational state for each ACE.
One ACL can be applied to multiple targets within the device, such as
interfaces of a networked device, applications or features running in
the device, etc. When applied to interfaces of a networked device,
the ACL is applied in a direction which indicates if it should be
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applied to packet entering (input) or leaving the device (output).
An example in the appendix shows how to express it in YANG model.
This draft tries to address the commonalities between all vendors and
create a common model, which can be augmented with proprietary
models. The base model is very simple and with this design we hope
to achieve needed flexibility for each vendor to extend the base
model.
3.1. ACL Modules
There are two YANG modules in the model. The first module, "ietf-
access-control-list", defines generic ACL aspects which are common to
all ACLs regardless of their type or vendor. In effect, the module
can be viewed as providing a generic ACL "superclass". It imports
the second module, "ietf-packet-fields". The match container in
"ietf-access-control-list" uses groupings in "ietf-packet-fields".
If there is a need to define new "matches" choice, such as IPFIX
[RFC5101], the container "matches" can be augmented.
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module: ietf-access-control-list
+--rw access-lists
+--rw acl* [acl-type acl-name]
+--rw acl-name string
+--rw acl-type acl-type
+--ro acl-oper-data
+--rw access-list-entries
+--rw ace* [rule-name]
+--rw rule-name string
+--rw matches
| +--rw (ace-type)?
| +--:(ace-ip)
| | +--rw (ace-ip-version)?
| | | +--:(ace-ipv4)
| | | | +--rw destination-ipv4-network? inet:ipv4-prefix
| | | | +--rw source-ipv4-network? inet:ipv4-prefix
| | | +--:(ace-ipv6)
| | | +--rw destination-ipv6-network? inet:ipv6-prefix
| | | +--rw source-ipv6-network? inet:ipv6-prefix
| | | +--rw flow-label? inet:ipv6-flow-label
| | +--rw dscp? inet:dscp
| | +--rw protocol? uint8
| | +--rw source-port-range!
| | | +--rw lower-port inet:port-number
| | | +--rw upper-port? inet:port-number
| | +--rw destination-port-range!
| | +--rw lower-port inet:port-number
| | +--rw upper-port? inet:port-number
| +--:(ace-eth)
| +--rw destination-mac-address? yang:mac-address
| +--rw destination-mac-address-mask? yang:mac-address
| +--rw source-mac-address? yang:mac-address
| +--rw source-mac-address-mask? yang:mac-address
+--rw actions
| +--rw (packet-handling)?
| +--:(deny)
| | +--rw deny? empty
| +--:(permit)
| +--rw permit? empty
+--ro ace-oper-data
+--ro match-counter? yang:counter64
Figure 1
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4. ACL YANG Models
4.1. IETF Access Control List module
"ietf-access-control-list" is the standard top level module for
access lists. The "access-lists" container stores a list of "acl".
Each "acl" has information identifying the access list by a
name("acl-name") and a list("access-list-entries") of rules
associated with the "acl-name". Each of the entries in the
list("access-list-entries"), indexed by the string "rule-name", has
containers defining "matches" and "actions". The "matches" define
criteria used to identify patterns in "ietf-packet-fields". The
"actions" define behavior to undertake once a "match" has been
identified.
<CODE BEGINS>file "ietf-access-control-list@2016-10-12.yang"
module ietf-access-control-list {
namespace "urn:ietf:params:xml:ns:yang:ietf-access-control-list";
prefix acl;
import ietf-yang-types {
prefix yang;
}
import ietf-packet-fields {
prefix packet-fields;
}
organization "IETF NETMOD (NETCONF Data Modeling Language)
Working Group";
contact
"WG Web: http://tools.ietf.org/wg/netmod/
WG List: netmod@ietf.org
Editor: Dean Bogdanovic
ivandean@gmail.com
Editor: Kiran Agrahara Sreenivasa
kkoushik@cisco.com
Editor: Lisa Huang
lyihuang16@gmail.com
Editor: Dana Blair
dblair@cisco.com";
description
"This YANG module defines a component that describing the
configuration of Access Control Lists (ACLs).
Copyright (c) 2016 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD
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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 2016-10-12 {
description
"Base model for Network Access Control List (ACL).";
reference
"RFC XXXX: Network Access Control List (ACL)
YANG Data Model";
}
/*
* Identities
*/
identity acl-base {
description
"Base Access Control List type for all Access Control List type
identifiers.";
}
identity ipv4-acl {
base acl:acl-base;
description
"ACL that primarily matches on fields from the IPv4 header
(e.g. IPv4 destination address) and layer 4 headers (e.g. TCP
destination port). An acl of type ipv4-acl does not contain
matches on fields in the ethernet header or the IPv6 header.";
}
identity ipv6-acl {
base acl:acl-base;
description
"ACL that primarily matches on fields from the IPv6 header
(e.g. IPv6 destination address) and layer 4 headers (e.g. TCP
destination port). An acl of type ipv6-acl does not contain
matches on fields in the ethernet header or the IPv4 header.";
}
identity eth-acl {
base acl:acl-base;
description
"ACL that primarily matches on fields in the ethernet header,
like 10/100/1000baseT or WiFi Access Control List. An acl of
type eth-acl does not contain matches on fields in the IPv4
header, IPv6 header or layer 4 headers.";
}
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/*
* Typedefs
*/
typedef acl-type {
type identityref {
base acl-base;
}
description
"This type is used to refer to an Access Control List
(ACL) type";
}
typedef access-control-list-ref {
type leafref {
path "/access-lists/acl/acl-name";
}
description
"This type is used by data models that need to reference an
Access Control List";
}
/*
* Configuration data nodes
*/
container access-lists {
description
"This is a top level container for Access Control Lists.
It can have one or more Access Control Lists.";
list acl {
key "acl-type acl-name";
description
"An Access Control List(ACL) is an ordered list of
Access List Entries (ACE). Each Access Control Entry has a
list of match criteria and a list of actions.
Since there are several kinds of Access Control Lists
implemented with different attributes for
different vendors, this
model accommodates customizing Access Control Lists for
each kind and for each vendor.";
leaf acl-name {
type string;
description
"The name of access-list. A device MAY restrict the length
and value of this name, possibly space and special
characters are not allowed.";
}
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leaf acl-type {
type acl-type;
description
"Type of access control list. Indicates the primary intended
type of match criteria (e.g. ethernet, IPv4, IPv6, mixed, etc)
used in the list instance.";
}
container acl-oper-data {
config false;
description
"Overall Access Control List operational data";
}
container access-list-entries {
description
"The access-list-entries container contains
a list of access-list-entries(ACE).";
list ace {
key "rule-name";
ordered-by user;
description
"List of access list entries(ACE)";
leaf rule-name {
type string;
description
"A unique name identifying this Access List
Entry(ACE).";
}
container matches {
description
"Definitions for match criteria for this Access List
Entry.";
choice ace-type {
description
"Type of access list entry.";
case ace-ip {
description "IP Access List Entry.";
choice ace-ip-version {
description
"IP version used in this Acess List Entry.";
case ace-ipv4 {
uses packet-fields:acl-ipv4-header-fields;
}
case ace-ipv6 {
uses packet-fields:acl-ipv6-header-fields;
}
}
uses packet-fields:acl-ip-header-fields;
}
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case ace-eth {
description
"Ethernet Access List entry.";
uses packet-fields:acl-eth-header-fields;
}
}
}
container actions {
description
"Definitions of action criteria for this Access List
Entry.";
choice packet-handling {
default "deny";
description
"Packet handling action.";
case deny {
leaf deny {
type empty;
description
"Deny action.";
}
}
case permit {
leaf permit {
type empty;
description
"Permit action.";
}
}
}
}
/*
* Operational state data nodes
*/
container ace-oper-data {
config false;
description
"Operational data for this Access List Entry.";
leaf match-counter {
type yang:counter64;
description
"Number of matches for this Access List Entry";
}
}
}
}
}
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}
}
<CODE ENDS>
4.2. IETF Packet Fields module
The packet fields module defines the necessary groups for matching on
fields in the packet including ethernet, ipv4, ipv6, and transport
layer fields. Since the number of match criteria is very large, the
base draft does not include these directly but references them by
"uses" to keep the base module simple. In case more match conditions
are needed, those can be added by augmenting choices within container
"matches" in ietf-access-control-list.yang model.
<CODE BEGINS>file "ietf-packet-fields@2016-10-12.yang"
module ietf-packet-fields {
namespace "urn:ietf:params:xml:ns:yang:ietf-packet-fields";
prefix packet-fields;
import ietf-inet-types {
prefix inet;
}
import ietf-yang-types {
prefix yang;
}
organization "IETF NETMOD (NETCONF Data Modeling Language) Working
Group";
contact
"WG Web: http://tools.ietf.org/wg/netmod/
WG List: netmod@ietf.org
Editor: Dean Bogdanovic
ivandean@gmail.com
Editor: Kiran Agrahara Sreenivasa
kkoushik@cisco.com
Editor: Lisa Huang
lyihuang16@gmail.com
Editor: Dana Blair
dblair@cisco.com";
description
"This YANG module defines groupings that are used by
ietf-access-control-list YANG module. Their usage is not
limited to ietf-access-control-list and can be
used anywhere as applicable.
Copyright (c) 2016 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
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to the license terms contained in, the Simplified BSD
License set forth in Section 4.c of the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2016-10-12 {
description
"Initial version of packet fields used by
ietf-access-control-list";
reference
"RFC XXXX: Network Access Control List (ACL)
YANG Data Model";
}
grouping acl-transport-header-fields {
description
"Transport header fields";
container source-port-range {
presence "Enables setting source port range";
description
"Inclusive range representing source ports to be used.
When only lower-port is present, it represents a single port.";
leaf lower-port {
type inet:port-number;
mandatory true;
description
"Lower boundary for port.";
}
leaf upper-port {
type inet:port-number;
must ". >= ../lower-port" {
error-message
"The upper-port must be greater than or equal to lower-port";
}
description
"Upper boundary for port . If existing, the upper port
must be greater or equal to lower-port.";
}
}
container destination-port-range {
presence "Enables setting destination port range";
description
"Inclusive range representing destination ports to be used. When
only lower-port is present, it represents a single port.";
leaf lower-port {
type inet:port-number;
mandatory true;
description
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"Lower boundary for port.";
}
leaf upper-port {
type inet:port-number;
must ". >= ../lower-port" {
error-message
"The upper-port must be greater than or equal to lower-port";
}
description
"Upper boundary for port. If existing, the upper port must
be greater or equal to lower-port";
}
}
}
grouping acl-ip-header-fields {
description
"IP header fields common to ipv4 and ipv6";
leaf dscp {
type inet:dscp;
description
"Value of dscp.";
}
leaf protocol {
type uint8;
description
"Internet Protocol number.";
}
uses acl-transport-header-fields;
}
grouping acl-ipv4-header-fields {
description
"Fields in IPv4 header.";
leaf destination-ipv4-network {
type inet:ipv4-prefix;
description
"Destination IPv4 address prefix.";
}
leaf source-ipv4-network {
type inet:ipv4-prefix;
description
"Source IPv4 address prefix.";
}
}
grouping acl-ipv6-header-fields {
description
"Fields in IPv6 header";
leaf destination-ipv6-network {
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type inet:ipv6-prefix;
description
"Destination IPv6 address prefix.";
}
leaf source-ipv6-network {
type inet:ipv6-prefix;
description
"Source IPv6 address prefix.";
}
leaf flow-label {
type inet:ipv6-flow-label;
description
"IPv6 Flow label.";
}
reference
"RFC 4291: IP Version 6 Addressing Architecture
RFC 4007: IPv6 Scoped Address Architecture
RFC 5952: A Recommendation for IPv6 Address Text Representation";
}
grouping acl-eth-header-fields {
description
"Fields in Ethernet header.";
leaf destination-mac-address {
type yang:mac-address;
description
"Destination IEEE 802 MAC address.";
}
leaf destination-mac-address-mask {
type yang:mac-address;
description
"Destination IEEE 802 MAC address mask.";
}
leaf source-mac-address {
type yang:mac-address;
description
"Source IEEE 802 MAC address.";
}
leaf source-mac-address-mask {
type yang:mac-address;
description
"Source IEEE 802 MAC address mask.";
}
reference
"IEEE 802: IEEE Standard for Local and Metropolitan Area
Networks: Overview and Architecture.";
}
}
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<CODE ENDS>
4.3. An ACL Example
Requirement: Deny tcp traffic from 10.10.10.1/24, destined to
11.11.11.1/24.
Here is the acl configuration xml for this Access Control List:
<?xml version='1.0' encoding='UTF-8'?>
<data xmlns="urn:ietf:params:xml:ns:netconf:base:1.0">
<access-lists xmlns="urn:ietf:params:xml:ns:yang:ietf-access-control-list">
<acl>
<acl-name>sample-ipv4-acl</acl-name>
<acl-type>ipv4</acl-type>
<access-list-entries>
<ace>
<rule-name>rule1</rule-name>
<matches>
<source-ipv4-network>
10.10.10.1/24
</source-ipv4-network>
<destination-ipv4-network>
11.11.11.1/24
</destination-ipv4-network>
</matches>
<actions>
<deny />
</actions>
<protocol>
tcp
</protocol>
</ace>
</access-list-entries>
</acl>
</access-lists>
</data>
The acl and aces can be described in CLI as the following:
access-list ipv4 sample-ipv4-acl
deny tcp 10.10.10.1/24 11.11.11.1/24
4.4. Port Range Usage Example
When a lower-port and an upper-port are both present, it represents a
range between lower-port and upper-port with both the lower-port and
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upper-port are included. When only a lower-port presents, it
represents a single port.
With the follow XML snippet:
<source-port-range>
<lower-port>16384</lower-port>
<upper-port>16387</upper-port>
</source-port-range>
This represents source ports 16384,16385, 16386, and 16387.
With the follow XML snippet:
<source-port-range>
<lower-port>16384</lower-port>
<upper-port>65535</upper-port>
</source-port-range>
This represents source ports greater than/equal to 16384 and less
than equal to 65535.
With the follow XML snippet:
<source-port-range>
<lower-port>21</lower-port>
</source-port-range>
This represents port 21.
5. Security Considerations
The YANG module defined in this memo is designed to be accessed via
the NETCONF [RFC6241]. The lowest NETCONF layer is the secure
transport layer and the mandatory-to-implement secure transport is
SSH [RFC6242]. The NETCONF Access Control Model ( NACM [RFC6536])
provides the means to restrict access for particular NETCONF users to
a pre-configured subset of all available NETCONF protocol operations
and content.
There are a number of data nodes defined in the YANG module which are
writable/creatable/deletable (i.e., config true, which is the
default). These data nodes may be considered sensitive or vulnerable
in some network environments. Write operations (e.g., <edit-config>)
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to these data nodes without proper protection can have a negative
effect on network operations.
These are the subtrees and data nodes and their sensitivity/
vulnerability:
/access-lists/acl/access-list-entries: This list specifies all the
configured access list entries on the device. Unauthorized write
access to this list can allow intruders to access and control the
system. Unauthorized read access to this list can allow intruders to
spoof packets with authorized addresses thereby compromising the
system.
6. IANA Considerations
This document registers a URI in the IETF XML registry [RFC3688].
Following the format in RFC 3688, the following registration is
requested to be made:
URI: urn:ietf:params:xml:ns:yang:ietf-access-control-list
URI: urn:ietf:params:xml:ns:yang:ietf-packet-fields
Registrant Contact: The IESG.
XML: N/A, the requested URI is an XML namespace.
This document registers a YANG module in the YANG Module Names
registry [RFC6020].
name: ietf-access-control-list namespace:
urn:ietf:params:xml:ns:yang:ietf-access-control-list prefix: ietf-acl
reference: RFC XXXX
name: ietf-packet-fields namespace: urn:ietf:params:xml:ns:yang:ietf-
packet-fields prefix: ietf-packet-fields reference: RFC XXXX
7. Acknowledgements
Alex Clemm, Andy Bierman and Lisa Huang started it by sketching out
an initial IETF draft in several past IETF meetings. That draft
included an ACL YANG model structure and a rich set of match filters,
and acknowledged contributions by Louis Fourie, Dana Blair, Tula
Kraiser, Patrick Gili, George Serpa, Martin Bjorklund, Kent Watsen,
and Phil Shafer. Many people have reviewed the various earlier
drafts that made the draft went into IETF charter.
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Dean Bogdanovic, Kiran Agrahara Sreenivasa, Lisa Huang, and Dana
Blair each evaluated the YANG model in previous draft separately and
then work together, to created a new ACL draft that can be supported
by different vendors. The new draft removes vendor specific
features, and gives examples to allow vendors to extend in their own
proprietary ACL. The earlier draft was superseded with the new one
that received more participation from many vendors.
Authors would like to thank Sonal Agarwal, Jason Sterne, Lada Lhotka,
Juergen Schoenwalder for their review of and suggestions to the
draft.
8. References
8.1. Normative References
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<http://www.rfc-editor.org/info/rfc3688>.
[RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for
the Network Configuration Protocol (NETCONF)", RFC 6020,
DOI 10.17487/RFC6020, October 2010,
<http://www.rfc-editor.org/info/rfc6020>.
[RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
and A. Bierman, Ed., "Network Configuration Protocol
(NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
<http://www.rfc-editor.org/info/rfc6241>.
[RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
<http://www.rfc-editor.org/info/rfc6242>.
[RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
Protocol (NETCONF) Access Control Model", RFC 6536, DOI
10.17487/RFC6536, March 2012,
<http://www.rfc-editor.org/info/rfc6536>.
8.2. Informative References
[RFC5101] Claise, B., Ed., "Specification of the IP Flow Information
Export (IPFIX) Protocol for the Exchange of IP Traffic
Flow Information", RFC 5101, DOI 10.17487/RFC5101, January
2008, <http://www.rfc-editor.org/info/rfc5101>.
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Appendix A. Extending ACL model examples
A.1. Example of extending existing model for route filtering
With proposed modular design, it is easy to extend the model with
other features. Those features can be standard features, like route
filters. Route filters match on specific IP addresses or ranges of
prefixes. Much like ACLs, they include some match criteria and
corresponding match action(s). For that reason, it is very simple to
extend existing ACL model with route filtering. The combination of a
route prefix and prefix length along with the type of match
determines how route filters are evaluated against incoming routes.
Different vendors have different match types and in this model we are
using only ones that are common across all vendors participating in
this draft. As in this example, the base ACL model can be extended
with company proprietary extensions, described in the next section.
module: example-ext-route-filter
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches:
+--rw (route-prefix)?
+--:(range)
+--rw (ipv4-range)?
| +--:(v4-lower-bound)
| | +--rw v4-lower-bound? inet:ipv4-prefix
| +--:(v4-upper-bound)
| +--rw v4-upper-bound? inet:ipv4-prefix
+--rw (ipv6-range)?
+--:(v6-lower-bound)
| +--rw v6-lower-bound? inet:ipv6-prefix
+--:(v6-upper-bound)
+--rw v6-upper-bound? inet:ipv6-prefix
file "example-ext-route-filter@2016-10-12.yang"
module example-ext-route-filter {
namespace "urn:ietf:params:xml:ns:yang:example-ext-route-filter";
prefix example-ext-route-filter;
import ietf-inet-types {
prefix "inet";
}
import ietf-access-control-list {
prefix "ietf-acl";
}
organization
"Route model group.";
contact
"abc@abc.com";
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description "
This module describes route filter as a collection of
match prefixes. When specifying a match prefix, you
can specify an exact match with a particular route or
a less precise match. You can configure either a
common action that applies to the entire list or an
action associated with each prefix.
";
revision 2016-10-12 {
description
"Creating Route-Filter extension model based on
ietf-access-control-list model";
reference " ";
}
augment "/ietf-acl:access-lists/ietf-acl:acl/"
+ "ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches"{
description "
This module augments the matches container in the ietf-acl
module with route filter specific actions
";
choice route-prefix{
description "Define route filter match criteria";
case range {
description
"Route falls between the lower prefix/prefix-length
and the upperprefix/prefix-length.";
choice ipv4-range {
description "Defines the IPv4 prefix range";
leaf v4-lower-bound {
type inet:ipv4-prefix;
description
"Defines the lower IPv4 prefix/prefix length";
}
leaf v4-upper-bound {
type inet:ipv4-prefix;
description
"Defines the upper IPv4 prefix/prefix length";
}
}
choice ipv6-range {
description "Defines the IPv6 prefix/prefix range";
leaf v6-lower-bound {
type inet:ipv6-prefix;
description
"Defines the lower IPv6 prefix/prefix length";
}
leaf v6-upper-bound {
type inet:ipv6-prefix;
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description
"Defines the upper IPv6 prefix/prefix length";
}
}
}
}
}
}
A.2. A company proprietary module example
Access control list typically does not exist in isolation. Instead,
they are associated with a certain scope in which they are applied,
for example, an interface of a set of interfaces. How to attach an
access control list to an interface (or other system artifact) is
outside the scope of this model, as it depends on the specifics of
the system model that is being applied. However, in general, the
general design pattern will involved adding a data node with a
reference, or set of references, to ACLs that are to be applied to
the interface. For this purpose, the type definition "access-
control-list-ref" can be used.
Module "example-newco-acl" is an example of company proprietary model
that augments "ietf-acl" module. It shows how to use 'augment' with
an XPath expression to add additional match criteria, action
criteria, and default actions when no ACE matches found, as well how
to attach an Access Control List to an interface. All these are
company proprietary extensions or system feature extensions.
"example-newco-acl" is just an example and it is expected from
vendors to create their own proprietary models.
The following figure is the tree structure of example-newco-acl. In
this example, /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-
list-entries/ ietf-acl:ace/ietf-acl:matches are augmented with two
new choices, protocol-payload-choice and metadata. The protocol-
payload-choice uses a grouping with an enumeration of all supported
protocol values. Metadata matches apply to fields associated with
the packet but not in the packet header such as input interface or
overall packet length. In other example, /ietf-acl:access-lists/
ietf-acl:acl/ietf-acl:access-list-entries/ ietf-acl:ace/ietf-
acl:actions are augmented with new choice of actions.
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module: example-newco-acl
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches:
+--rw vlan-tagged? uint16
+--rw mpls-unicast? uint16
+--rw mpls-multicast? uint16
+--rw ipv4? uint16
+--rw ipv6? uint16
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches:
+--rw ipv4-ttl? uint8
+--rw ipv4-len? uint16
+--rw ipv4-ihl? uint8
+--rw ipv4-id? uint16
+--rw ipv4-flags? ipv4-flags-type
+--rw ipv4-offset? uint16
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches:
+--rw (protocol-payload-choice)?
| +--:(protocol-payload)
| +--rw protocol-payload* [value-keyword]
| +--rw value-keyword enumeration
+--rw (metadata)?
+--:(interface-name)
+--rw interface-name* [input-interface]
+--rw input-interface ietf-if:interface-ref
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:actions:
+--rw (action)?
+--:(count)
| +--rw count? string
+--:(policer)
| +--rw policer? string
+--:(hiearchical-policer)
+--rw hierarchitacl-policer? string
augment /ietf-acl:access-lists/ietf-acl:acl:
+--rw default-actions
+--rw deny? empty
augment /ietf-if:interfaces/ietf-if:interface:
+--rw acl
+--rw acl-name? ietf-acl:access-control-list-ref
+--ro match-counter? yang:counter64
+--rw (direction)?
+--:(in)
| +--rw in? empty
+--:(out)
+--rw out? empty
augment /ietf-acl:access-lists/ietf-acl:acl/ietf-acl:acl-oper-data:
+--ro targets
+--ro (interface)?
+--:(interface-name)
+--ro interface-name* ietf-if:interface-ref
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module example-newco-acl {
yang-version 1.1;
namespace "urn:newco:params:xml:ns:yang:example-newco-acl";
prefix example-newco-acl;
import ietf-access-control-list {
prefix "ietf-acl";
}
import ietf-interfaces {
prefix "ietf-if";
}
import ietf-yang-types {
prefix yang;
}
organization
"Newco model group.";
contact
"abc@newco.com";
description
"This YANG module augment IETF ACL Yang.";
revision 2016-10-12{
description
"Creating NewCo proprietary extensions to ietf-acl model";
reference
"RFC XXXX: Network Access Control List (ACL)
YANG Data Model";
}
typedef known-ether-type {
type enumeration {
enum "ipv4" {
value 2048; // 0x0800
description "Internet Protocol version 4 (IPv4)";
}
enum "vlan-tagged" {
value 33024; // 0x8100
description "VLAN-tagged frame (IEEE 802.1Q) & Shortest Path Bridging IEEE 802.1aq[4]";
}
enum "ipv6" {
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value 34525; // 0x86DD
description "Internet Protocol Version 6 (IPv6)";
}
enum "mpls-unicast" {
value 34887; // 0x8847
description "MPLS unicast";
}
enum "mpls-multicast" {
value 34888; // 0x8848
description "MPLS multicast";
}
}
description "Listing supported Ethertypes";
}
typedef ipv4-flags-type {
type bits {
bit ipv4-reserved {
position 0;
description "reserved bit";
}
bit ipv4-DF {
position 1;
description "DF bit";
}
bit ipv4-MF {
position 2;
description "MF bit";
}
}
description "IPv4 flag types";
}
augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches" {
when "ietf-acl:access-lists/ietf-acl:acl/ietf-acl:acl-type = 'ace-eth'";
description "additional MAC header matching";
leaf vlan-tagged {
type uint16;
description "Ethernet frame with VLAN tag";
}
leaf mpls-unicast {
type uint16;
description "Ethernet frame with MPLS unicast payload";
}
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leaf mpls-multicast {
type uint16;
description "Ethernet frame with MPLS multicast payload";
}
leaf ipv4 {
type uint16;
description "Ethernet frame with IPv4 unicast payload";
}
leaf ipv6 {
type uint16;
description "Ethernet frame with IPv4 unicast payload";
}
}
augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches" {
when "ietf-acl:access-lists/ietf-acl:acl/ietf-acl:acl-type = 'ipv4-acl'";
description "additional IP header information";
leaf ipv4-ttl {
type uint8;
description "time to live of a given packet as defined in RFC791";
}
leaf ipv4-len {
type uint16;
description "total packet length as defined in RFC791";
}
leaf ipv4-ihl {
type uint8 {
range 0..15;
}
description "Internet Header Length in 32 bit words (see RFC791). Note
that while the minimum value for this field in a packet is
5, we leave open the possibility here that the packet has
been corrupted.";
}
leaf ipv4-id {
type uint16;
description "Identification as decribed in RFC791";
}
leaf ipv4-flags {
type ipv4-flags-type;
description "IPv4 flags as defined in RFC791";
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}
leaf ipv4-offset {
type uint16 {
range 0..8191;
}
description "Matches on the packet fragment offset";
}
}
augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:matches" {
description "Newco proprietary simple filter matches";
choice protocol-payload-choice {
description "Newo proprietary payload match condition";
list protocol-payload {
key value-keyword;
ordered-by user;
description "Match protocol payload";
uses match-simple-payload-protocol-value;
}
}
choice metadata {
description "Newco proprietary interface match condition";
list interface-name {
key input-interface;
ordered-by user;
description "Match interface name";
uses metadata;
}
}
}
augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:access-list-entries/ietf-acl:ace/ietf-acl:actions" {
description "Newco proprietary simple filter actions";
choice action {
description "";
case count {
description "Count the packet in the named counter";
leaf count {
type string;
description "";
}
}
case policer {
description "Name of policer to use to rate-limit traffic";
leaf policer {
type string;
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description "";
}
}
case hiearchical-policer {
description "Name of hierarchical policer to use to
rate-limit traffic";
leaf hierarchitacl-policer{
type string;
description "";
}
}
}
}
augment "/ietf-acl:access-lists/ietf-acl:acl" {
description "Newco proprietary default action";
container default-actions {
description
"Actions that occur if no access-list entry is matched.";
leaf deny {
type empty;
description "";
}
}
}
grouping metadata {
description
"Fields associated with a packet which are not in
the header.";
leaf input-interface {
type ietf-if:interface-ref {
require-instance false;
}
description
"Packet was received on this interface";
}
}
grouping match-simple-payload-protocol-value {
description "Newco proprietary payload";
leaf value-keyword {
type enumeration {
enum icmp {
description "Internet Control Message Protocol";
}
enum icmp6 {
description "Internet Control Message Protocol Version 6";
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}
enum range {
description "Range of values";
}
}
description "(null)";
}
}
augment "/ietf-if:interfaces/ietf-if:interface" {
description "Apply ACL to interfaces";
container acl{
description "ACL related properties.";
leaf acl-name {
type ietf-acl:access-control-list-ref;
description "Access Control List name.";
}
leaf match-counter {
type yang:counter64;
config false;
description
"Total match count for Access Control
List on this interface";
}
choice direction {
description "Applying ACL in which traffic direction";
leaf in {
type empty;
description "Inbound traffic";
}
leaf out {
type empty;
description "Outbound traffic";
}
}
}
}
augment "/ietf-acl:access-lists/ietf-acl:acl/ietf-acl:acl-oper-data" {
description
"This is an example on how to apply acl to a target to collect
operational data";
container targets{
description "To which object is the ACL attached to";
choice interface{
description "Access Control List was attached to this interface";
leaf-list interface-name{
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type ietf-if:interface-ref {
require-instance true;
}
description "Attached to this interface name";
}
}
}
}
}
Draft authors expect that different vendors will provide their own
yang models as in the example above, which is the augmentation of the
base model
A.3. Example to augment model with mixed ACL type
As vendors (or IETF) add more features to ACL, the model is easily
augmented. One of such augmentations can be to add support for mixed
type of ACLs, where acl-type-base can be augmented like in example
below:
identity mixed-l3-acl {
base "access-control-list:acl-type-base";
description "ACL that contains a mix of entries that
primarily match on fields in IPv4 headers and entries
that primarily match on fields in IPv6 headers.
Matching on layer 4 header fields may also exist in the
list. An acl of type mixed-l3-acl does not contain
matches on fields in the ethernet header.";
}
identity mixed-l2-l3-acl {
base "access-control-list:acl-type-base";
description "ACL that contains a mix of entries that
primarily match on fields in ethernet headers, entries
that primarily match on fields in IPv4 headers, and entries
that primarily match on fields in IPv6 headers. Matching on
layer 4 header fields may also exist in the list.";
}
A.4. Linux nftables
As Linux platform is becoming more popular as networking platform,
the Linux data model is changing. Previously ACLs in Linux were
highly protocol specific and different utilities were used (iptables,
ip6tables, arptables, ebtables), so each one had separate data model.
Recently, this has changed and a single utility, nftables, has been
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developed. With a single application, it has a single data model for
filewall filters and it follows very similarly to the ietf-access-
control list module proposed in this draft. The nftables support
input and output ACEs and each ACE can be defined with match and
action.
The example in Section 4.3 can be configured using nftable tool as
below.
nft add table ip filter
nft add chain filter input
nft add rule ip filter input ip protocol tcp ip saddr 10.10.10.1/24 drop
The configuration entries added in nftable would be.
table ip filter {
chain input {
ip protocol tcp ip saddr 10.10.10.1/24 drop
}
}
We can see that there are many similarities between Linux nftables
and IETF ACL YANG data models and its extension models. It should be
fairly easy to do translation between ACL YANG model described in
this draft and Linux nftables.
Authors' Addresses
Dean Bogdanovic
Volta Networks
Email: ivandean@gmail.com
Kiran Agrahara Sreenivasa
Cisco Systems
Email: kkoushik@cisco.com
Lisa Huang
General Electric
Email: lyihuang16@gmail.com
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Dana Blair
Cisco Systems
Email: dblair@cisco.com
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