Internet DRAFT - draft-lear-ietf-netmod-acl-dnsname
draft-lear-ietf-netmod-acl-dnsname
Network Working Group E. Lear
Internet-Draft Cisco Systems
Intended status: Standards Track January 19, 2016
Expires: July 22, 2016
Using DNS Names in the IETF ACL Model
draft-lear-ietf-netmod-acl-dnsname-00
Abstract
End points are commonly referenced by higher level functions through
the DNS. This is especially the case in cloud-based functions, which
might have hundreds of IP addresses for the same name. This brief
memo extends the IETF-ACL model to allow access-control via domain
names.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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This Internet-Draft will expire on July 22, 2016.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Element Definitions . . . . . . . . . . . . . . . . . . . . . 3
2.1. source-dnsname . . . . . . . . . . . . . . . . . . . . . 3
2.2. destination-dnsname . . . . . . . . . . . . . . . . . . . 3
3. The ietf-acl-dnsname Model . . . . . . . . . . . . . . . . . 3
4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6
8. Normative References . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
The IETF-ACL model [I-D.ietf-netmod-acl-model] specifies a schema for
access lists. That model is intentionally kept constrained to the
small number of packet-passing functions that are considered
ubiquitous. While that is a necessary step, there are a number of
circumstances in which it will not be sufficient. In a world where
load balancing and shifting commonly takes place, it may not be
practical to maintain the complete list of IP addresses in all
instances. Furthermore, even in more static environments,
occasionally the name to address mapping needs to change. Lastly,
there are resources that may not be tied to packet processing at all
that may yet be well described by this augmentation. Allowing domain
names in ACLs reduces the number of points within a network that need
to be reconfigured when such changes take place.
This memo specifies an extension to IETF-ACL model such that domain
names may be referenced by augmenting the "matches" element.
Different implementations may deploy differing methods to maintain
the mapping between IP address and domain name, if indeed any are
needed. However, the intent is that resources that are referred to
using a name should be authorized (or not) within an access list.
The structure of the change is as follows:
augment
/acl:access-lists/acl:acl/acl:access-list-entries
/acl:ace/acl:matches/acl:ace-type/acl:ace-ip:
+--rw source-dnsname? inet:host
+--rw destination-dnsname? inet:host
The choice of this particular point in the access-list model is based
on the assumption that we are in some way referring to IP-related
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resources, as that is what the DNS returns. A domain name in our
context is defined in [RFC6991].
2. Element Definitions
The following elements are defined.
2.1. source-dnsname
The argument corresponds to a domain name of a source as specified by
inet:host. Depending on how the model is used, it may or may not be
resolved, as required by the implementation and circumstances.
2.2. destination-dnsname
The argument corresponds to a domain name of a destination as
specified by inet:host. Depending on how the model is used, it may
or may not be resolved, as required by the implementation and
circumstances.
3. The ietf-acl-dnsname Model
<CODE BEGINS>file "ietf-acl-dnsname.yang";
module ietf-acl-dnsname {
yang-version 1;
namespace "urn:ietf:params:xml:ns:yang:ietf-acl-dnsname";
prefix "ietf-acl-dnsname";
import ietf-access-control-list {
prefix "acl";
}
import ietf-inet-types
{
prefix "inet";
}
organization
"Cisco Systems, Inc.";
contact
"Eliot Lear
lear@cisco.com
";
description
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"This YANG module defines a component that augments the
IETF description of an access list to allow dns names
as matching criteria.";
revision "2016-01-14" {
description "Initial revision";
reference "This document?";
}
augment "/acl:access-lists/acl:acl/" +
"acl:access-list-entries/acl:ace/" +
"acl:matches/acl:ace-type/acl:ace-ip" {
description "adding domain names to matching";
leaf source-dnsname {
type inet:host;
description "domain name to be matched against";
}
leaf destination-dnsname {
type inet:host;
description "domain name to be matched against";
}
}
}
<CODE ENDS>
4. Example
The following example is taken from [I-D.ietf-netmod-acl-model] (the
optional and irrelevant components have been removed). It allows
traffic from www.cloud.example.com.
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<?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"
xmlns:ietf-acl-dnsname="urn:ietf:params:xml:ns:yang:ietf-acl-dnsname">
<acl>
<acl-oper-data />
<access-list-entries>
<ace>
<matches>
<source-dnsname>
www.cloud.example.com
</destination-dnsname>
</matches>
<actions>
<permit />
</actions>
<rule-name>rule1<rule-name/>
</ace>
</access-list-entries>
<acl-name>sample-dns-acl<acl-name/>
<acl-type>ipv4-acl<acl-type/>
</acl>
</access-lists>
</data>
5. Security Considerations
If the mapping between a domain name and the underlying resource to
which it refers becomes stale, the access list will be incorrect. It
is therefore important that implementations employ some means for
maintaining the mapping, if it is required. In those circumstances,
when other systems are in play, those other systems would be required
to indicate what domains they are attempting to connect to. Under
the current circumstances, this is readily observable. However, in
future such information sharing may raise privacy concerns, and the
name and mapping may not be available to the system employing the ACL
model.
6. IANA Considerations
The IANA is not requested to make any changes. The RFC Editor is
requested to remove this section prior to publication.
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7. Acknowledgments
The author wishes to acknowledge Kiran Koushik and Einar Nilsen-
Nygaard for their review and contributions to this work.
8. Normative References
[I-D.ietf-netmod-acl-model]
Bogdanovic, D., Koushik, K., Huang, L., and D. Blair,
"Network Access Control List (ACL) YANG Data Model",
draft-ietf-netmod-acl-model-06 (work in progress),
December 2015.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC
6991, DOI 10.17487/RFC6991, July 2013,
<http://www.rfc-editor.org/info/rfc6991>.
Author's Address
Eliot Lear
Cisco Systems
Richtistrasse 7
Wallisellen CH-8304
Switzerland
Phone: +41 44 878 9200
Email: lear@cisco.com
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