| NETMOD WG | D. Bogdanovic |
| Internet-Draft | Juniper Networks |
| Intended status: Standards Track | K. Sreenivasa |
| Expires: September 6, 2015 | Brocade Communications System |
| L. Huang | |
| D. Blair | |
| Cisco Systems | |
| March 5, 2015 |
Network Access Control List (ACL) YANG Data Model
draft-ietf-netmod-acl-model-02
This document describes a data model of Access Control List (ACL) basic building blocks.
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 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 6, 2015.
Copyright (c) 2015 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.
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 metadata match criteria.
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.
ACE: Access Control Entry
ACL: Access Control List
AFI: Address Field Identifier
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
This document defines a YANG [RFC6020] data model for the configuration of ACLs. It is very important that model can be easily reused between vendors and between applications.
ACL implementations in every device may vary greatly in terms of the filter constructs and actions that they support. Therefore this draft proposes a simple model that can be augmented by vendor proprietary models.
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 and metadata matching. 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 overall operational state for the ACL and operational state for each ACE, targets where the ACL applied. 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 applied to packet entering (input) or leaving the device (output).
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.
There are two YANG modules in the model. The first module, "ietf-acl", 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-acl" uses groupings in "ietf-packet-fields". The "ietf-packet-fields" modules can easily be extended to reuse definitions from other modules such as IPFIX [RFC5101] or migrate proprietary augmented module definitions into the standard module.
module: ietf-acl
+--rw access-lists
+--rw access-list* [access-control-list-name]
+--rw access-control-list-name string
+--rw access-control-list-type? access-control-list-type
+--ro access-control-list-oper-data
| +--ro (targets)?
| +--:(interface-name)
| +--ro interface-name* string
+--rw access-list-entries
+--rw access-list-entry* [rule-name]
+--rw rule-name string
+--rw matches
| +--rw (access-list-entries-type)?
| | +--:(access-list-entries-ip)
| | | +--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
| | | +--rw dscp? inet:dscp
| | | +--rw protocol? uint8
| | | +--rw (access-list-entries-ip-version)?
| | | +--:(access-list-entries-ipv4)
| | | | +--rw destination-ipv4-network? inet:ipv4-prefix
| | | | +--rw source-ipv4-network? inet:ipv4-prefix
| | | +--:(access-list-entries-ipv6)
| | | +--rw destination-ipv6-network? inet:ipv6-prefix
| | | +--rw source-ipv6-network? inet:ipv6-prefix
| | | +--rw flow-label? inet:ipv6-flow-label
| | +--:(access-list-entries-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 input-interface? string
| +--rw absolute
| +--rw start? yang:date-and-time
| +--rw end? yang:date-and-time
| +--rw active? boolean
+--rw actions
| +--rw (packet-handling)?
| +--:(deny)
| | +--rw deny? empty
| +--:(permit)
| +--rw permit? empty
+--ro access-list-entries-oper-data
+--ro match-counter? yang:counter64
"ietf-acl" is the standard top level module for Access lists. It has a container for "access-list" to store access list information. This container 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" have 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-acl@2015-03-04.yang"
module ietf-acl {
yang-version 1;
namespace "urn:ietf:params:xml:ns:yang:ietf-acl";
prefix access-control-list;
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
WG Chair: Juergen Schoenwaelder
j.schoenwaelder@jacobs-university.de
WG Chair: Tom Nadeau
tnadeau@lucidvision.com
Editor: Dean Bogdanovic
deanb@juniper.net
Editor: Kiran Agrahara Sreenivasa
kkoushik@brocade.com
Editor: Lisa Huang
yihuan@cisco.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) 2015 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD
License set forth in Section 4.c of the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
revision 2015-03-04 {
description "Base model for Network Access Control List (ACL).";
reference
"RFC XXXX: Network Access Control List (ACL)
YANG Data Model";
}
identity access-control-list-base {
description "Base access control list type for all access control list type
identifiers.";
}
identity IP-access-control-list {
base "access-control-list:access-control-list-base";
description "IP-access control list is common name for layer 3 and 4 access
control list types. It is common among vendors to call 3-tupple or 5 tupple
IP access control lists";
}
identity eth-access-control-list {
base "access-control-list:access-control-list-base";
description "Ethernet access control list is name for layer 2 Ethernet
technology access control list types, like 10/100/1000baseT or WiFi
access control list";
}
typedef access-control-list-type {
type identityref {
base "access-control-list-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/access-list/access-control-list-name";
}
description "This type is used by data models that need to referenced an
access control list";
}
container access-lists {
description
"This is top level container for Access Control Lists. It can have one
or more Access Control List.";
list access-list {
key access-control-list-name;
description "An access list (acl) is an ordered list of
access list entries (ACE). Each access control entries 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
each and different for each vendor, this
model accommodates customizing access control lists for
each kind and for each vendor.";
leaf access-control-list-name {
type string;
description "The name of access-list. A device MAY restrict the length
and value of this name, possibly space and special characters are not
allowed.";
}
leaf access-control-list-type {
type access-control-list-type;
description "Type of access control list. When this
type is not explicitely specified, if vendor implementation permits,
the access control entires in the list can be mixed,
by containing L2, L3 and L4 entries";
}
container access-control-list-oper-data {
config false;
description "Overall access control list operational data";
choice targets{
description "List of targets where access control list is applied";
leaf-list interface-name {
type string;
description "Interfaces where access control list is applied";
}
}
}
container access-list-entries {
description "The access-list-entries container contains
a list of access-list-entry(ACE).";
list access-list-entry {
key rule-name;
ordered-by user;
description "List of access list entries(ACE)";
leaf rule-name {
type string;
description "Entry name.";
}
container matches {
description "Define match criteria";
choice access-list-entries-type {
description "Type of access list entry.";
case access-list-entries-ip {
uses packet-fields:access-control-list-ip-header-fields;
choice access-list-entries-ip-version {
description "Choice of IP version.";
case access-list-entries-ipv4 {
uses packet-fields:access-control-list-ipv4-header-fields;
}
case access-list-entries-ipv6 {
uses packet-fields:access-control-list-ipv6-header-fields;
}
}
}
case access-list-entries-eth {
description "Ethernet MAC address entry.";
uses packet-fields:access-control-list-eth-header-fields;
}
}
uses packet-fields:metadata;
}
container actions {
description "Define action criteria";
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.";
}
}
}
}
container access-list-entries-oper-data {
config false;
description "Per access list entries operational data";
leaf match-counter {
type yang:counter64;
description "Number of matches for an access list entry";
}
}
}
}
}
}
}
<CODE ENDS>
The packet fields module defines the necessary groups for matching on fields in the packet including ethernet, ipv4, ipv6, transport layer fields and metadata. These groupings can be augmented to include other proprietary matching criteria. 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.
<CODE BEGINS>file "ietf-packet-fields@2015-03-04.yang"
module ietf-packet-fields {
yang-version 1;
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
WG Chair: Juergen Schoenwaelder
j.schoenwaelder@jacobs-university.de
WG Chair: Tom Nadeau
tnadeau@lucidvision.com
Editor: Dean Bogdanovic
deanb@juniper.net
Editor: Kiran Agrahara Sreenivasa
kkoushik@brocade.com
Editor: Lisa Huang
yihuan@cisco.com
Editor: Dana Blair
dblair@cisco.com";
description
"This YANG module defines groupings that used by ietf-acl
but not limited to acl.
Copyright (c) 2015 IETF Trust and the persons identified as
the document authors. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD
License set forth in Section 4.c of the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
revision 2015-03-04 {
description "Initial version of packet fields used by
access-lists";
reference
"RFC XXXX: Network Access Control List (ACL)
YANG Data Model";
}
grouping access-control-list-transport-header-fields {
description "Transport header fields";
container source-port-range {
description "inclusive range of source ports";
leaf lower-port {
type inet:port-number;
mandatory true;
description "Lower boundary.";
}
leaf upper-port {
type inet:port-number;
description "Upper boundary. If exist, upper port must be greater or
equal to lower port.";
}
}
container destination-port-range {
description "inclusive range of destination ports";
leaf lower-port {
type inet:port-number;
mandatory true;
description "Lower boundary.";
}
leaf upper-port {
type inet:port-number;
description "Upper boundary.";
}
}
}
grouping access-control-list-ip-header-fields {
description "Header fields common to ipv4 and ipv6";
uses access-control-list-transport-header-fields;
leaf dscp {
type inet:dscp;
description "Value of dscp.";
}
leaf protocol {
type uint8;
description "Internet Protocol number.";
}
}
grouping access-control-list-ipv4-header-fields {
description "fields in IPv4 header";
leaf destination-ipv4-network {
type inet:ipv4-prefix;
description "One or more ip addresses.";
}
leaf source-ipv4-network {
type inet:ipv4-prefix;
description "One or more ip addresses.";
}
}
grouping access-control-list-ipv6-header-fields {
description "fields in IPv6 header";
leaf destination-ipv6-network {
type inet:ipv6-prefix;
description "One or more ip addresses.";
}
leaf source-ipv6-network {
type inet:ipv6-prefix;
description "One or more ip addresses.";
}
leaf flow-label {
type inet:ipv6-flow-label;
description "Flow label.";
}
}
grouping access-control-list-eth-header-fields {
description "fields in ethernet header";
leaf destination-mac-address {
type yang:mac-address;
description "Mac addresses.";
}
leaf destination-mac-address-mask {
type yang:mac-address;
description "Mac addresses mask.";
}
leaf source-mac-address {
type yang:mac-address;
description "Mac addresses.";
}
leaf source-mac-address-mask {
type yang:mac-address;
description "Mac addresses mask.";
}
}
grouping timerange {
description "Time range contains time
segments to allow access-control-list to be
active/inactive when the system time
is within the time segments.";
container absolute {
description
"Absolute time and date that
the associated function starts
going into effect.";
leaf start {
type yang:date-and-time;
description
"Start time and date";
}
leaf end {
type yang:date-and-time;
description "Absolute end time and date";
}
leaf active {
type boolean;
default "true";
description
"Specify the associated function
active or inactive state when
starts going into effect";
}
} // container absolute
} //grouping timerange
grouping metadata {
description "Fields associated with a packet but not in
the header";
leaf input-interface {
type string;
description "Packet was received on this interface";
}
uses timerange;
}
}
<CODE ENDS>
Requirement: Deny All traffic from 10.10.10.1 bound for host 10.10.10.255 from leaving.
In order to achieve the requirement, an name access control list is needed. The acl and aces can be described in CLI as the following:
access-list ip iacl deny tcp host 10.10.10.1 host 10.10.10.255
Figure 1
Here is the example acl configuration xml:
<rpc message-id="101" xmlns:nc="urn:cisco:params:xml:ns:yang:ietf-acl:1.0">
// replace with IANA namespace when assigned
<edit-config>
<target>
<running/>
</target>
<config>
<top xmlns="http://example.com/schema/1.2/config">
<access-lists>
<access-list>
<access-control-list-name>sample-ip-acl</access-control-list-name>
<access-list-entries>
<access-list-entry>
<rule-name>telnet-block-rule</rule-name>
<matches>
<destination-ipv4-address>10.10.10.255/24</destination-ipv4-address>
<source-ipv4-address>10.10.10.1/24</source-ipv4-address>
</matches>
<actions>
<deny/>
</actions>
</access-list-entry>
</access-list-entries>
</access-list>
</access-lists>
</top>
</config>
</edit-config>
</rpc>
Figure 2
When a lower-port and an upper-port are both present, it represents a range between lower-port and upper-port with both the lower-port and upper-port are included. When only a lower-port presents, it represents a single port.
With the follow XML snippet:
<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.
With the follow XML snippet:
<source-port-range>
<lower-port>21</lower-port>
</source-port-range>
This represents port 21.
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 for it (iptables, ip6tables, arptables, ebtables). Recently, this has changed and a single utility, nftables, has been provided. This utility follows very similarly the same base model as proposed in this draft. The nftables support input and output ACEs and each ACE can be defined with match and action.
The YANG module defined in this memo is designed to be accessed via the NETCONF protocol [RFC6241] [RFC6241]. The lowest NETCONF layer is the secure transport layer and the mandatory-to-implement secure transport is SSH [RFC6242] [RFC6242]. The NETCONF access control model [RFC6536] [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>) 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:
/ietf-acl:access-lists/access-list/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.
This document registers a URI in the IETF XML registry [RFC3688] [RFC3688]. Following the format in RFC 3688, the following registration is requested to be made:
URI: urn:ietf:params:xml:ns:yang:ietf-acl
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-acl namespace: urn:ietf:params:xml:ns:yang:ietf-acl 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
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.
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.
| [RFC3688] | Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, January 2004. |
| [RFC6020] | Bjorklund, M., "YANG - A Data Modeling Language for the Network Configuration Protocol (NETCONF)", RFC 6020, October 2010. |
| [RFC6241] | Enns, R., Bjorklund, M., Schoenwaelder, J. and A. Bierman, "Network Configuration Protocol (NETCONF)", RFC 6241, June 2011. |
| [RFC6242] | Wasserman, M., "Using the NETCONF Protocol over Secure Shell (SSH)", RFC 6242, June 2011. |
| [RFC6536] | Bierman, A. and M. Bjorklund, "Network Configuration Protocol (NETCONF) Access Control Model", RFC 6536, March 2012. |
| [RFC5101] | Claise, B., "Specification of the IP Flow Information Export (IPFIX) Protocol for the Exchange of IP Traffic Flow Information", RFC 5101, January 2008. |
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.
<CODE BEGINS> file "std-ext-route-filter@2015-02-14.yang"
module std-ext-route-filter {
yang-version 1;
namespace "urn:ietf:params:xml:ns:yang:ietf-route-filter";
prefix std-ext-route-filter;
import ietf-inet-types {
prefix "inet";
}
import ietf-acl {
prefix "ietf-acl";
}
organization
"IETF NETMOD (NETCONF Data Modeling Language) Working Group";
contact
"WG Web: http://tools.ietf.org/wg/netmod/
WG List: netmod@ietf.org
WG Chair: Juergen Schoenwaelder
j.schoenwaelder@jacobs-university.de
WG Chair: Tom Nadeau
tnadeau@lucidvision.com
Editor: Dean Bogdanovic
deanb@juniper.net
Editor: Kiran Agrahara Sreenivasa
kkoushik@brocade.com
Editor: Lisa Huang
yihuan@cisco.com
Editor: Dana Blair
dblair@cisco.com";
description "
This module describes route filter as a collection of
match prefixes. When specifying a match prefix, you
can specify an exact match with a particular route or
a less precise match. You can configure either a
common action that applies to the entire list or an
action associated with each prefix.
";
revision 2015-02-14 {
description "creating Route-Filter extension model based on ietf-acl model";
reference " ";
}
augment "/ietf-acl:access-lists/ietf-acl:access-list
/ietf-acl:access-list-entries/
ietf-acl:access-list-entry/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 upper
prefix/prefix-length.
";
choice ipv4-range {
description "Defines the lower IPv4 prefix/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;
description "Defines the upper IPv6 prefix/prefix length";
}
}
}
}
}
}
<CODE ENDS>
Module "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. All these are company proprietary extensions or system feature extensions. "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 newco-acl. In this example, ietf-acl:access-lists/ietf-acl:access-list/ietf-acl:access-list-entries/ietf-acl:access-list-entry/ietf-acl:matches: are augmented with a new choice, protocol-payload-choice. The protocol-payload-choice uses a grouping with an enumeration of all supported protocol values. In other example, ietf-acl:access-lists/ietf-acl:access-list/ietf-acl:access-list-entries/ietf-acl:access-list-entry/ietf-acl:actions are augmented with new choice of actions.
module: newco-acl
augment /ietf-acl:access-lists/ietf-acl:access-list
/ietf-acl:access-list-entries/
ietf-acl:access-list-entry/ietf-acl:matches:
+--rw (protocol-payload-choice)?
+--:(protocol-payload)
+--rw protocol-payload* [value-keyword]
+--rw value-keyword enumeration
augment /ietf-acl:access-lists/ietf-acl:access-list
/ietf-acl:access-list-entries/
ietf-acl:access-list-entry/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:access-list:
+--rw default-actions
+--rw deny? empty
<CODE BEGINS> file "newco-acl@2015-03-04.yang"
module newco-acl {
yang-version 1;
namespace "urn:newco:params:xml:ns:yang:newco-acl";
prefix newco-acl;
import ietf-acl {
prefix "ietf-acl";
}
revision 2015-03-04{
description "creating NewCo proprietary extensions to ietf-acl model";
}
augment "/ietf-acl:access-lists/ietf-acl:access-list
/ietf-acl:access-list-entries/
ietf-acl:access-list-entry/ietf-acl:matches" {
description "Newco proprietary simple filter matches";
choice protocol-payload-choice {
list protocol-payload {
key value-keyword;
ordered-by user;
description "Match protocol payload";
uses match-simple-payload-protocol-value;
}
}
}
augment "/ietf-acl:access-lists/ietf-acl:access-list/ietf-acl:access-list-entries/ietf-acl:access-list-entry/ietf-acl:actions" {
description "Newco proprietary simple filter actions";
choice action {
case count {
description "Count the packet in the named counter";
leaf count {
type string;
}
}
case policer {
description "Name of policer to use to rate-limit traffic";
leaf policer {
type string;
}
}
case hiearchical-policer {
description "Name of hierarchical policer to use to
rate-limit traffic";
leaf hierarchitacl-policer{
type string;
}
}
}
}
augment "/ietf-acl:access-lists/ietf-acl:access-list" {
container default-actions {
description "Actions that occur if no access-list entry is matched.";
leaf deny {
type empty;
}
}
}
grouping match-simple-payload-protocol-value {
leaf value-keyword {
description "(null)";
type enumeration {
enum icmp {
description "Internet Control Message Protocol";
}
enum icmp6 {
description "Internet Control Message Protocol Version 6";
}
enum range {
description "Range of values";
}
}
}
}
}
<CODE ENDS>
Draft authors expect that different vendors will provide their own yang models as in the example above, which is the extension of the base model
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 SPF 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 dada 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.
This is an example of attaching an access control list to an interface.
<CODE BEGINS> file "interface model augmentation with ACL
@2015-03-04.yang"
import ietf-acl {
prefix "ietf-acl";
}
import ietf-interface {
prefix "ietf-if";
}
import ietf-yang-types {
prefix "yang";
}
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;
mandatory true;
description "Access Control List name.";
}
leaf match-counter {
type yang:counter64;
config false;
description "Total match count for access control list ";
}
choice direction {
leaf in { type empty;}
leaf out { type empty;}
}
}
}
<CODE ENDS>