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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-21) exists of draft-ietf-netmod-acl-model-06 Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group E. Lear 3 Internet-Draft Cisco Systems 4 Intended status: Standards Track January 19, 2016 5 Expires: July 22, 2016 7 Using DNS Names in the IETF ACL Model 8 draft-lear-ietf-netmod-acl-dnsname-00 10 Abstract 12 End points are commonly referenced by higher level functions through 13 the DNS. This is especially the case in cloud-based functions, which 14 might have hundreds of IP addresses for the same name. This brief 15 memo extends the IETF-ACL model to allow access-control via domain 16 names. 18 Status of This Memo 20 This Internet-Draft is submitted in full conformance with the 21 provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet Engineering 24 Task Force (IETF). Note that other groups may also distribute 25 working documents as Internet-Drafts. The list of current Internet- 26 Drafts is at http://datatracker.ietf.org/drafts/current/. 28 Internet-Drafts are draft documents valid for a maximum of six months 29 and may be updated, replaced, or obsoleted by other documents at any 30 time. It is inappropriate to use Internet-Drafts as reference 31 material or to cite them other than as "work in progress." 33 This Internet-Draft will expire on July 22, 2016. 35 Copyright Notice 37 Copyright (c) 2016 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with respect 45 to this document. Code Components extracted from this document must 46 include Simplified BSD License text as described in Section 4.e of 47 the Trust Legal Provisions and are provided without warranty as 48 described in the Simplified BSD License. 50 Table of Contents 52 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 53 2. Element Definitions . . . . . . . . . . . . . . . . . . . . . 3 54 2.1. source-dnsname . . . . . . . . . . . . . . . . . . . . . 3 55 2.2. destination-dnsname . . . . . . . . . . . . . . . . . . . 3 56 3. The ietf-acl-dnsname Model . . . . . . . . . . . . . . . . . 3 57 4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 58 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 59 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 60 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 6 61 8. Normative References . . . . . . . . . . . . . . . . . . . . 6 62 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 64 1. Introduction 66 The IETF-ACL model [I-D.ietf-netmod-acl-model] specifies a schema for 67 access lists. That model is intentionally kept constrained to the 68 small number of packet-passing functions that are considered 69 ubiquitous. While that is a necessary step, there are a number of 70 circumstances in which it will not be sufficient. In a world where 71 load balancing and shifting commonly takes place, it may not be 72 practical to maintain the complete list of IP addresses in all 73 instances. Furthermore, even in more static environments, 74 occasionally the name to address mapping needs to change. Lastly, 75 there are resources that may not be tied to packet processing at all 76 that may yet be well described by this augmentation. Allowing domain 77 names in ACLs reduces the number of points within a network that need 78 to be reconfigured when such changes take place. 80 This memo specifies an extension to IETF-ACL model such that domain 81 names may be referenced by augmenting the "matches" element. 82 Different implementations may deploy differing methods to maintain 83 the mapping between IP address and domain name, if indeed any are 84 needed. However, the intent is that resources that are referred to 85 using a name should be authorized (or not) within an access list. 87 The structure of the change is as follows: 89 augment 90 /acl:access-lists/acl:acl/acl:access-list-entries 91 /acl:ace/acl:matches/acl:ace-type/acl:ace-ip: 92 +--rw source-dnsname? inet:host 93 +--rw destination-dnsname? inet:host 95 The choice of this particular point in the access-list model is based 96 on the assumption that we are in some way referring to IP-related 97 resources, as that is what the DNS returns. A domain name in our 98 context is defined in [RFC6991]. 100 2. Element Definitions 102 The following elements are defined. 104 2.1. source-dnsname 106 The argument corresponds to a domain name of a source as specified by 107 inet:host. Depending on how the model is used, it may or may not be 108 resolved, as required by the implementation and circumstances. 110 2.2. destination-dnsname 112 The argument corresponds to a domain name of a destination as 113 specified by inet:host. Depending on how the model is used, it may 114 or may not be resolved, as required by the implementation and 115 circumstances. 117 3. The ietf-acl-dnsname Model 119 file "ietf-acl-dnsname.yang"; 121 module ietf-acl-dnsname { 122 yang-version 1; 123 namespace "urn:ietf:params:xml:ns:yang:ietf-acl-dnsname"; 124 prefix "ietf-acl-dnsname"; 126 import ietf-access-control-list { 127 prefix "acl"; 128 } 130 import ietf-inet-types 131 { 132 prefix "inet"; 133 } 135 organization 136 "Cisco Systems, Inc."; 138 contact 139 "Eliot Lear 140 lear@cisco.com 141 "; 143 description 144 "This YANG module defines a component that augments the 145 IETF description of an access list to allow dns names 146 as matching criteria."; 148 revision "2016-01-14" { 149 description "Initial revision"; 150 reference "This document?"; 151 } 153 augment "/acl:access-lists/acl:acl/" + 154 "acl:access-list-entries/acl:ace/" + 155 "acl:matches/acl:ace-type/acl:ace-ip" { 156 description "adding domain names to matching"; 158 leaf source-dnsname { 159 type inet:host; 160 description "domain name to be matched against"; 161 } 162 leaf destination-dnsname { 163 type inet:host; 164 description "domain name to be matched against"; 165 } 166 } 168 } 170 172 4. Example 174 The following example is taken from [I-D.ietf-netmod-acl-model] (the 175 optional and irrelevant components have been removed). It allows 176 traffic from www.cloud.example.com. 178 179 180 183 184 185 186 187 188 189 www.cloud.example.com 190 191 192 193 194 195 rule1 196 197 198 sample-dns-acl 199 ipv4-acl 200 201 202 204 5. Security Considerations 206 If the mapping between a domain name and the underlying resource to 207 which it refers becomes stale, the access list will be incorrect. It 208 is therefore important that implementations employ some means for 209 maintaining the mapping, if it is required. In those circumstances, 210 when other systems are in play, those other systems would be required 211 to indicate what domains they are attempting to connect to. Under 212 the current circumstances, this is readily observable. However, in 213 future such information sharing may raise privacy concerns, and the 214 name and mapping may not be available to the system employing the ACL 215 model. 217 6. IANA Considerations 219 The IANA is not requested to make any changes. The RFC Editor is 220 requested to remove this section prior to publication. 222 7. Acknowledgments 224 The author wishes to acknowledge Kiran Koushik and Einar Nilsen- 225 Nygaard for their review and contributions to this work. 227 8. Normative References 229 [I-D.ietf-netmod-acl-model] 230 Bogdanovic, D., Koushik, K., Huang, L., and D. Blair, 231 "Network Access Control List (ACL) YANG Data Model", 232 draft-ietf-netmod-acl-model-06 (work in progress), 233 December 2015. 235 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", RFC 236 6991, DOI 10.17487/RFC6991, July 2013, 237 . 239 Author's Address 241 Eliot Lear 242 Cisco Systems 243 Richtistrasse 7 244 Wallisellen CH-8304 245 Switzerland 247 Phone: +41 44 878 9200 248 Email: lear@cisco.com