idnits 2.17.1 draft-ietf-opsawg-mud-10.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Line 529 has weird spacing: '...cl-type ide...' == Line 534 has weird spacing: '...cl-type ide...' == Line 981 has weird spacing: '...ecified model...' -- The document date (September 15, 2017) is 2415 days in the past. Is this intentional? 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-45) exists of draft-ietf-anima-bootstrapping-keyinfra-07 == Outdated reference: A later version (-21) exists of draft-ietf-netmod-acl-model-13 -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE8021AB' ** Obsolete normative reference: RFC 2818 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) == Outdated reference: A later version (-20) exists of draft-ietf-netmod-rfc6087bis-14 -- Obsolete informational reference (is this intentional?): RFC 7042 (Obsoleted by RFC 9542) Summary: 2 errors (**), 0 flaws (~~), 7 warnings (==), 3 comments (--). 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 R. Droms 5 Expires: March 19, 2018 6 D. Romascanu 7 September 15, 2017 9 Manufacturer Usage Description Specification 10 draft-ietf-opsawg-mud-10 12 Abstract 14 This memo specifies a component-based architecture for manufacturer 15 usage descriptions (MUD). The goal of MUD is to provide a means for 16 Things to signal to the network what sort of access and network 17 functionality they require to properly function. The initial focus 18 is on access control. Later work can delve into other aspects. 20 This memo specifies two YANG modules, IPv4 and IPv6 DHCP options, an 21 LLDP TLV, a URL suffix specification, an X.509 certificate extension 22 and a means to sign and verify the descriptions. 24 Status of This Memo 26 This Internet-Draft is submitted in full conformance with the 27 provisions of BCP 78 and BCP 79. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF). Note that other groups may also distribute 31 working documents as Internet-Drafts. The list of current Internet- 32 Drafts is at http://datatracker.ietf.org/drafts/current/. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 This Internet-Draft will expire on March 19, 2018. 41 Copyright Notice 43 Copyright (c) 2017 IETF Trust and the persons identified as the 44 document authors. All rights reserved. 46 This document is subject to BCP 78 and the IETF Trust's Legal 47 Provisions Relating to IETF Documents 48 (http://trustee.ietf.org/license-info) in effect on the date of 49 publication of this document. Please review these documents 50 carefully, as they describe your rights and restrictions with respect 51 to this document. Code Components extracted from this document must 52 include Simplified BSD License text as described in Section 4.e of 53 the Trust Legal Provisions and are provided without warranty as 54 described in the Simplified BSD License. 56 Table of Contents 58 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 59 1.1. What MUD doesn't do . . . . . . . . . . . . . . . . . . . 4 60 1.2. A Simple Example . . . . . . . . . . . . . . . . . . . . 5 61 1.3. Determining Intended Use . . . . . . . . . . . . . . . . 5 62 1.4. Finding A Policy: The MUD URL . . . . . . . . . . . . . . 5 63 1.5. Types of Policies . . . . . . . . . . . . . . . . . . . . 6 64 1.6. Terminology . . . . . . . . . . . . . . . . . . . . . . . 8 65 1.7. The Manufacturer Usage Description Architecture . . . . . 8 66 1.8. Order of operations . . . . . . . . . . . . . . . . . . . 10 67 2. The MUD Model and Semantic Meaning . . . . . . . . . . . . . 10 68 3. Data Node Definitions . . . . . . . . . . . . . . . . . . . . 12 69 3.1. to-device-policy and from-device-policy containers . . . 12 70 3.2. last-update . . . . . . . . . . . . . . . . . . . . . . . 13 71 3.3. cache-validity . . . . . . . . . . . . . . . . . . . . . 13 72 3.4. masa-server . . . . . . . . . . . . . . . . . . . . . . . 13 73 3.5. is-supported . . . . . . . . . . . . . . . . . . . . . . 13 74 3.6. systeminfo . . . . . . . . . . . . . . . . . . . . . . . 13 75 3.7. extensions . . . . . . . . . . . . . . . . . . . . . . . 13 76 3.8. manufacturer . . . . . . . . . . . . . . . . . . . . . . 14 77 3.9. same-manufacturer . . . . . . . . . . . . . . . . . . . . 14 78 3.10. model . . . . . . . . . . . . . . . . . . . . . . . . . . 14 79 3.11. local-networks . . . . . . . . . . . . . . . . . . . . . 14 80 3.12. controller . . . . . . . . . . . . . . . . . . . . . . . 15 81 3.13. my-controller . . . . . . . . . . . . . . . . . . . . . . 15 82 3.14. direction-initiated . . . . . . . . . . . . . . . . . . . 15 83 4. Processing of the MUD file . . . . . . . . . . . . . . . . . 15 84 5. What does a MUD URL look like? . . . . . . . . . . . . . . . 16 85 6. The MUD YANG Model . . . . . . . . . . . . . . . . . . . . . 17 86 7. The Domain Name Extension to the ACL Model . . . . . . . . . 22 87 7.1. source-dnsname . . . . . . . . . . . . . . . . . . . . . 23 88 7.2. destination-dnsname . . . . . . . . . . . . . . . . . . . 23 89 7.3. The ietf-acldns Model . . . . . . . . . . . . . . . . . . 23 90 8. MUD File Example . . . . . . . . . . . . . . . . . . . . . . 25 91 9. The MUD URL DHCP Option . . . . . . . . . . . . . . . . . . . 27 92 9.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 28 93 9.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 28 94 9.3. Relay Requirements . . . . . . . . . . . . . . . . . . . 29 95 10. The Manufacturer Usage Description (MUD) URL X.509 Extension 29 96 11. The Manufacturer Usage Description LLDP extension . . . . . . 30 97 12. Creating and Processing of Signed MUD Files . . . . . . . . . 32 98 12.1. Creating a MUD file signature . . . . . . . . . . . . . 32 99 12.2. Verifying a MUD file signature . . . . . . . . . . . . . 32 100 13. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 33 101 14. Deployment Considerations . . . . . . . . . . . . . . . . . . 33 102 15. Security Considerations . . . . . . . . . . . . . . . . . . . 34 103 16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 36 104 16.1. YANG Module Registrations . . . . . . . . . . . . . . . 36 105 16.2. DHCPv4 and DHCPv6 Options . . . . . . . . . . . . . . . 36 106 16.3. PKIX Extensions . . . . . . . . . . . . . . . . . . . . 37 107 16.4. Well Known URI Suffix . . . . . . . . . . . . . . . . . 37 108 16.5. MIME Media-type Registration for MUD files . . . . . . . 37 109 16.6. LLDP IANA TLV Subtype Registry . . . . . . . . . . . . . 38 110 16.7. The MUD Well Known Universal Resource Name (URNs) . . . 39 111 16.8. Extensions Registry . . . . . . . . . . . . . . . . . . 39 112 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 39 113 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 40 114 18.1. Normative References . . . . . . . . . . . . . . . . . . 40 115 18.2. Informative References . . . . . . . . . . . . . . . . . 42 116 Appendix A. Changes from Earlier Versions . . . . . . . . . . . 43 117 Appendix B. Default MUD nodes . . . . . . . . . . . . . . . . . 45 118 Appendix C. A Sample Extension: DETNET-indicator . . . . . . . . 49 119 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 53 121 1. Introduction 123 The Internet has largely been constructed on general purpose 124 computers; those devices that may be used for a purpose that is 125 specified by those who buy the device. [RFC1984] presumed that an 126 end device would be most capable of protecting itself. This made 127 sense when the typical device was a workstation or a mainframe, and 128 it continues to make sense for general purpose computing devices 129 today, including laptops, smart phones, and tablets. 131 [RFC7452] discusses design patterns for, and poses questions about, 132 smart objects. Let us then posit a group of objects that are 133 specifically NOT general purpose computers. These devices have a 134 purpose to their use. By definition, therefore, all other purposes 135 are NOT intended. The combination of these two statements can be 136 restated as a manufacturer usage description (MUD) that can be 137 applied at various points within a network. Although this memo may 138 seem to stress access requirements, usage intent also consists of 139 quality of service needs a device may have. 141 We use the notion of "manufacturer" loosely in this context, to 142 simply mean the entity or organization that will state how a device 143 is intended to be used. In the context of a lightbulb, this might 144 indeed be the lightbulb manufacturer. In the context of a smarter 145 device that has a built in Linux stack, it might be an integrator of 146 that device. The key points are that the device itself is expected 147 to serve a limited purpose, and that there may exist an organization 148 in the supply chain of that device that will take responsibility for 149 informing the network about that purpose. 151 The intent MUD is to solve for the following problems: 153 o Substantially reduce the threat surface on a device entering a 154 network to those communications intended by the manufacturer. 156 o Provide for a means to scale network policies to the ever- 157 increasing number types of devices in the network. 159 o Provide a means to address at least some vulnerabilities in a way 160 that is faster than it might take to update systems. This will be 161 particularly true for systems that are no longer supported by 162 their manufacturer. 164 o Keep the cost of implementation of such a system to the bare 165 minimum. 167 MUD consists of three architectural building blocks: * A classifier 168 that a device emits that can be used to locate a description; * The 169 description itself, including how it is interpreted, and; * A means 170 for local network management systems to retrieve the description. 172 In this specification we describe each of these building blocks and 173 how they are intended to be used together. However, they may also be 174 used separately, independent of this specification by local 175 deployments for their own purposes. 177 1.1. What MUD doesn't do 179 MUD is not intended to address network authorization of general 180 purpose computers, as their manufacturers cannot envision a specific 181 communication pattern to describe. In addition, even those devices 182 that have a single or small number of uses might have very broad 183 communication patterns. MUD on its own is not for them either. 185 No matter how good a MUD-enabled network is, it will never replace 186 the need for manufacturers to patch vulnerabilities. It may, 187 however, provide network administrators with some additional 188 protection when those vulnerabilities exist. 190 Finally, no matter what the manufacturer specifies in a MUD file, 191 these are not directives, but suggestions. How they are instantiated 192 locally will depend on many factors, and is ultimately up to the 193 local network administrator. 195 1.2. A Simple Example 197 A light bulb is intended to light a room. It may be remotely 198 controlled through the network; and it may make use of a rendezvous 199 service of some form that an app on smart phone accesses. What we 200 can say about that light bulb, then, is that all other network access 201 is unwanted. It will not contact a news service, nor speak to the 202 refrigerator, and it has no need of a printer or other devices. It 203 has no social networking friends. Therefore, an access list applied 204 to it that states that it will only connect to the single rendezvous 205 service will not impede the light bulb in performing its function, 206 while at the same time allowing the network to provide both it and 207 other devices an additional layer of protection. 209 1.3. Determining Intended Use 211 The notion of intended use is in itself not new. Network 212 administrators apply access lists every day to allow for only such 213 use. This notion of white listing was well described by Chapman and 214 Zwicky in [FW95]. Profiling systems that make use of heuristics to 215 identify types of systems have existed for years as well. 217 A Thing could just as easily tell the network what sort of protection 218 it requires without going into what sort of system it is. This 219 would, in effect, be the converse of [RFC7488]. In seeking a general 220 purpose solution, however, we assume that a device has so few 221 capabilities that it will implement the least necessary capabilities 222 to function properly. This is a basic economic constraint. Unless 223 the network would refuse access to such a device, its developers 224 would have no reason to provide the network any information. To 225 date, such an assertion has held true. 227 1.4. Finding A Policy: The MUD URL 229 Our work begins with the device emitting a Universal Resource Locator 230 (URL) [RFC3986]. This URL serves both to classify the device type 231 and to provide a means to locate a policy file. 233 In this memo three means are defined to emit the MUD URL. One is a 234 DHCP option[RFC2131],[RFC3315] that the DHCP client uses to inform 235 the DHCP server. The DHCP server may take further actions, such as 236 retrieve the URL or otherwise pass it along to network management 237 system or controller. The second method defined is an X.509 238 constraint. The IEEE has developed [IEEE8021AR] that provides a 239 certificate-based approach to communicate device characteristics, 240 which itself relies on [RFC5280]. The MUD URL extension is non- 241 critical, as required by IEEE 802.1AR. Various means may be used to 242 communicate that certificate, including Tunnel Extensible 243 Authentication Protocol (TEAP) [RFC7170]. Finally, a Link Layer 244 Discovery Protocol (LLDP) frame is defined [IEEE8021AB]. 246 It is possible that there may be other means for a MUD URL to be 247 learned by a network. For instance, some devices may already be 248 fielded or have very limited ability to communicate a MUD URL, and 249 yet can be identified through some means, such as a serial number or 250 a public key. In these cases, manufacturers may be able to map those 251 identifies to particular MUD URLs (or even the files themselves). 252 Similarly, there may be alternative resolution mechanisms available 253 for situations where Internet connectivity is limited or does not 254 exist. Such mechanisms are not described in this memo, but are 255 possible. Implementors should allow for this sort of flexibility of 256 how MUD URLs may be learned. 258 1.5. Types of Policies 260 When the MUD URL is resolved, the MUD controller retrieves a file 261 that describes what sort of communications a device is designed to 262 have. The manufacturer may specify either specific hosts for cloud 263 based services or certain classes for access within an operational 264 network. An example of a class might be "devices of a specified 265 manufacturer type", where the manufacturer type itself is indicated 266 simply by the authority component (e.g, the domain name) of the MUD 267 URL. Another example might be to allow or disallow local access. 268 Just like other policies, these may be combined. For example: 270 Allow access to devices of the same manufacturer 271 Allow access to and from controllers via COAP 272 Allow access to local DNS/DHCP 273 Deny all other access 275 To add a bit more depth that should not be a stretch of anyone's 276 imagination, one could also make use of port-based access lists. 277 Thus a printer might have a description that states: 279 Allow access for port IPP or port LPD 280 Allow local access for port HTTP 281 Deny all other access 283 In this way anyone can print to the printer, but local access would 284 be required for the management interface. 286 The files that are retrieved are intended to be closely aligned to 287 existing network architectures so that they are easy to deploy. We 288 make use of YANG [RFC6020] because of the time and effort spent to 289 develop accurate and adequate models for use by network devices. 290 JSON is used as a serialization for compactness and readability, 291 relative to XML. Other formats may be chosen with later versions of 292 MUD. 294 While the policy examples given here focus on access control, this is 295 not intended to be the sole focus. By structuring the model 296 described in this document with clear extension points, so that other 297 descriptions could be included. One that often comes to mind is 298 quality of service. 300 The YANG modules specified here are extensions of 301 [I-D.ietf-netmod-acl-model]. The extensions to this model allow for 302 a manufacturer to express classes of systems that a manufacturer 303 would find necessary for the proper function of the device. Two 304 modules are specified. The first module specifies a means for domain 305 names to be used in ACLs so that devices that have their controllers 306 in the cloud may be appropriately authorized with domain names, where 307 the mapping of those names to addresses may rapidly change. 309 The other module abstracts away IP addresses into certain classes 310 that are instantiated into actual IP addresses through local 311 processing. Through these classes, manufacturers can specify how the 312 device is designed to communicate, so that network elements can be 313 configured by local systems that have local topological knowledge. 314 That is, the deployment populates the classes that the manufacturer 315 specifies. The abstractions below map to zero or more hosts, as 316 follows: 318 Manufacturer: A device made by a particular manufacturer, as 319 identified by the authority component of its MUD-URL 321 same-manufacturer: Devices that have the same authority component of 322 their MUD-URL. 324 Controller: Devices that the local network administrator admits to 325 the particular class. 327 my-controller: Devices associated with the MUD-URL of a device that 328 the administrator admits. 330 local: The class of IP addresses that are scoped within some 331 administrative boundary. By default it is suggested that this be 332 the local subnet. 334 The "manufacturer" classes can be easily specified by the 335 manufacturer, whereas controller classes are initially envisioned to 336 be specified by the administrator. 338 Because manufacturers do not know who will be using their devices, it 339 is important for functionality referenced in usage descriptions to be 340 relatively ubiquitous, and mature. For these reasons only a limited 341 subset YANG-based configuration of is permitted in a MUD file. 343 1.6. Terminology 345 MUD: manufacturer usage description. 347 MUD file: a file containing YANG-based JSON that describes a Thing 348 and associated suggested specific network behavior. 350 MUD file server: a web server that hosts a MUD file. 352 MUD controller: the system that requests and receives the MUD file 353 from the MUD server. After it has processed a MUD file it may 354 direct changes to relevant network elements. 356 MUD URL: a URL that can be used by the MUD controller to receive the 357 MUD file. 359 Thing: the device emitting a MUD URL. 361 Manufacturer: the entity that configures the Thing to emit the MUD 362 URL and the one who asserts a recommendation in a MUD file. The 363 manufacturer might not always be the entity that constructs a 364 Thing. It could, for instance, be a systems integrator, or even a 365 component provider. 367 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 368 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 369 document are to be interpreted as described in [RFC2119]. 371 1.7. The Manufacturer Usage Description Architecture 373 With these components laid out we now have the basis for an 374 archicture. This leads us to ASCII art. 376 ....................................... 377 . ____________ . _____________ 378 . | | . | | 379 . | MUD |-->get URL-->| MUD | 380 . | Controller | .(https) | File Server | 381 . End system network |____________|<-MUD file<-<|_____________| 382 . . . 383 . . . 384 . _______ _________ . 385 .| | (dhcp et al) | router | . 386 .| Thing |---->MUD URL-->| or | . 387 .|_______| | switch | . 388 . |_________| . 389 ....................................... 391 Figure 1: MUD Architecture 393 In the above diagram, the switch or router collects MUD URLs and 394 forwards them to the network management system for processing. This 395 happens in different ways, depending on how the URL is communicated. 396 For instance, in the case of DHCP, the DHCP server might receive the 397 URL and then process it. In the case of IEEE 802.1X, the switch 398 would carry the URL via a certificate to the authentication server 399 via EAP over Radius[RFC3748], which would then process it. One 400 method to do this is TEAP, described in [RFC7170]. The certificate 401 extension is described below. 403 The information returned by the web site is valid for the duration of 404 the Thing's connection, or as specified in the description. Thus if 405 the Thing is disconnected, any associated configuration in the switch 406 can be removed. Similarly, from time to time the description may be 407 refreshed, based on new capabilities or communication patterns or 408 vulnerabilities. 410 The web site is typically run by or on behalf of the manufacturer. 411 Its domain name is that of the authority found in the MUD URL. For 412 legacy cases where Things cannot emit a URL, if the switch is able to 413 determine the appropriate URL, it may proxy it, the trivial cases 414 being a map between some registered Thing or port and a URL. 416 The role of the MUD controller in this environment is to do the 417 following: 419 o receive MUD URLs, 421 o retrieve MUD files, 422 o translate abstractions in the MUD files to specific Thing 423 configuration, 425 o maintain and update any required mappings of the abstractions, and 427 o update network elements with appropriate configuration. 429 A MUD controller may be a component of a AAA or network management 430 system. Communication within those systems and from those systems to 431 network elements is beyond the scope of this memo. 433 1.8. Order of operations 435 As mentioned above, MUD contains architectural building blocks, and 436 so order of operation may vary. However, here is one clear intended 437 example: 439 1. Thing emits URL. 441 2. That URL is forwarded to a MUD controller by the nearest switch 442 (how this happens depends on the way in which the MUD URL is 443 emitted). 445 3. The MUD controller retrieves the MUD file and signature from the 446 MUD file server, assuming it doesn't already have copies. After 447 validating the signature, it may test the URL against a web or 448 domain reputation service, and it may test any hosts within the 449 file against those reputation services, as it deems fit. 451 4. The MUD controller may query the administrator for permission to 452 add the Thing and associated policy. If the Thing is known or 453 the Thing type is known, it may skip this step. 455 5. The MUD controller instantiates local configuration based on the 456 abstractions defined in this document. 458 6. The MUD controller configures the switch nearest the Thing. 459 Other systems may be configured as well. 461 7. When the Thing disconnects, policy is removed. 463 2. The MUD Model and Semantic Meaning 465 A MUD file consists of JSON based on a YANG model. For purposes of 466 MUD, the nodes that can be modified are access lists as augmented by 467 this model. The MUD file is limited to the serialization of only the 468 following YANG schema: 470 o ietf-access-control-list [I-D.ietf-netmod-acl-model] 472 o ietf-mud (this document) 474 o ietf-acldns (this document) 476 Extensions may be used to add additional schema. This is described 477 further on. 479 To provide the widest possible deployability, with the exceptions of 480 "acl-name", "acl-type", "rule-name", and TCP and UDP source and 481 destination port information, publishers of MUD files SHOULD limit 482 the use of ACL model leaf nodes expressed to those found in this 483 specification. Absent any extensions, MUD files are assumed to 484 implement only the following ACL model features: 486 o icmp-acl, ipv6-acl, tcp-acl, udp-acl, ipv4-acl, and ipv6-acl 488 MUD controllers MAY ignore any particular component of a description 489 or MAY ignore the description in its entirety, and SHOULD carefully 490 inspect all MUD descriptions. Publishers of MUD files MUST NOT 491 include other nodes except as described in Section 3.7. See that 492 section for more information. 494 ======= This module is structured into three parts: 496 o The first container "mud" holds information that is relevant to 497 retrieval and validity of the MUD file itself, as well as policy 498 intended to and from the Thing. 500 o The second component augments the matching container of the ACL 501 model to add several nodes that are relevant to the MUD URL, or 502 otherwise abstracted for use within a local environment. 504 o The third component augments the tcp-acl container of the ACL 505 model to add the ability to match on the direction of initiation 506 of a TCP connection. 508 A valid MUD file will contain two root objects, a "mud" container and 509 an "access-lists" container. Extensions may add additional root 510 objects as required. 512 A simplified graphical representation of the data models is used in 513 this document. The meaning of the symbols in these diagrams is 514 explained in [I-D.ietf-netmod-rfc6087bis]. 516 module: ietf-mud 517 +--rw mud! 518 +--rw mud-url inet:uri 519 +--rw last-update yang:date-and-time 520 +--rw cache-validity? uint8 521 +--rw masa-server? inet:uri 522 +--rw is-supported boolean 523 +--rw systeminfo? inet:uri 524 +--rw extensions* string 525 +--rw from-device-policy 526 | +--rw access-lists 527 | +--rw access-list* [acl-name acl-type] 528 | +--rw acl-name -> /acl:access-lists/acl/acl-name 529 | +--rw acl-type identityref 530 +--rw to-device-policy 531 +--rw access-lists 532 +--rw access-list* [acl-name acl-type] 533 +--rw acl-name -> /acl:access-lists/acl/acl-name 534 +--rw acl-type identityref 535 augment /acl:access-lists/acl:acl/acl:aces/ 536 acl:ace/acl:matches: 537 +--rw mud-acl 538 +--rw manufacturer? inet:host 539 +--rw same-manufacturer? empty 540 +--rw model? inet:uri 541 +--rw local-networks? empty 542 +--rw controller? inet:uri 543 +--rw my-controller? empty 544 augment /acl:access-lists/acl:acl/acl:aces/ 545 acl:ace/acl:matches/acl:tcp-acl: 546 +--rw direction-initiated? direction 548 3. Data Node Definitions 550 Note that in this section, when we use the term "match" we are 551 referring to the ACL model "matches" node, and thus returns positive 552 such that an action should be applied. 554 The following nodes are defined. 556 3.1. to-device-policy and from-device-policy containers 558 [I-D.ietf-netmod-acl-model] describes access-lists but does not 559 attempt to indicate where they are applied as that is handled 560 elsewhere in a configuration. However, in this case, a MUD file must 561 be explicit in describing the communication pattern of a Thing, and 562 that includes indicating what is to be permitted or denied in either 563 direction of communication. Hence each of these containers indicate 564 the appropriate direction of a flow in association with a particular 565 Thing. They contain references to specific access-lists. 567 3.2. last-update 569 This is a date-and-time value of when the MUD file was generated. 570 This is akin to a version number. Its form is taken from [RFC6991] 571 which, for those keeping score, in turn was taken from Section 5.6 of 572 [RFC3339], which was taken from [ISO.8601.1988]. 574 3.3. cache-validity 576 This uint8 is the period of time in hours that a network management 577 station MUST wait since its last retrieval before checking for an 578 update. It is RECOMMENDED that this value be no less than 24 and 579 MUST NOT be more than 168 for any Thing that is supported. This 580 period SHOULD be no shorter than any period determined through HTTP 581 caching directives (e.g., "cache-control" or "Expires"). N.B., 582 expiring of this timer does not require the MUD controller to discard 583 the MUD file, nor terminate access to a Thing. See Section 15 for 584 more information. 586 3.4. masa-server 588 This optional node refers to the URL that should be used to resolve 589 the MASA service, as specified in 590 [I-D.ietf-anima-bootstrapping-keyinfra]. 592 3.5. is-supported 594 This boolean is an indication from the manufacturer to the network 595 administrator as to whether or not the Thing is supported. In this 596 context a Thing is said to be supported if the manufacturer might 597 issue an update to the Thing or if the manufacturer might update the 598 MUD file. 600 3.6. systeminfo 602 This is a URL that points to a description of the Thing to be 603 connected. The intent is for administrators to be able to read about 604 what the Thing is the first time the MUD-URL is used. 606 3.7. extensions 608 This optional leaf-list names MUD extensions that are used in the MUD 609 file. Note that NO MUD extensions may be used in a MUD file prior to 610 the extensions being declared. Implementations MUST ignore any node 611 in this file that they do not understand. 613 Note that extensions can either extend the MUD file as described in 614 the previous paragraph, or they might reference other work. A good 615 example of how this might be done is the masa-server URI that is 616 defined in the base model. We say nothing about the semantics of 617 that work here, but rather leave that to the underlying specification 618 found in [I-D.ietf-anima-bootstrapping-keyinfra]. 620 3.8. manufacturer 622 This node consists of a hostname that would be matched against the 623 authority component of another Thing's MUD URL. In its simplest form 624 "manufacturer" and "same-manufacturer" may be implemented as access- 625 lists. In more complex forms, additional network capabilities may be 626 used. For example, if one saw the line "manufacturer" : 627 "flobbidy.example.com", then all Things that registered with a MUD 628 URL that contained flobbity.example.com in its authority section 629 would match. 631 3.9. same-manufacturer 633 This is an equivalent for when the manufacturer element is used to 634 indicate the authority that is found in another Thing's MUD URL 635 matches that of the authority found in this Thing's MUD URL. For 636 example, if the Thing's MUD URL were https://b1.example.com/.well- 637 known/mud/v1/ThingV1, then all devices that had MUD URL with an 638 authority section of b1.example.com would match. 640 3.10. model 642 This string matches the entire MUD URL, thus covering the model that 643 is unique within the context of the authority. It may contain not 644 only model information, but versioning information as well, and any 645 other information that the manufacturer wishes to add. The intended 646 use is for devices of this precise class to match, to permit or deny 647 communication between one another. 649 3.11. local-networks 651 This null-valued node expands to include local networks. Its default 652 expansion is that packets must not traverse toward a default route 653 that is received from the router. However, administrators may expand 654 the expression as is appropriate in their deployments. 656 3.12. controller 658 This URI specifies a value that a controller will register with the 659 mud controller. The node then is expanded to the set of hosts that 660 are so registered. This node may also be a URN. In this case, the 661 URN describes a well known service, such as DNS or NTP. 663 Great care should be used when invoking the controller class. For 664 one thing, it requires some understanding by the administrator as to 665 when it is appropriate. Classes that are standardized may make it 666 possible to easily name devices that support standard functions. For 667 instance, the MUD controller could have some knowledge of which DNS 668 servers should be used for any particular group of Things. Non- 669 standard classes will likely require some sort of administrator 670 interaction. Pre-registration in such classes by controllers with 671 the MUD server is encouraged. The mechanism to do that is beyond the 672 scope of this work. 674 Controller URIs MAY take the form of a URL (e.g. "http[s]://"). 675 However, MUD controllers MUST NOT resolve and retrieve such files, 676 and it is RECOMMENDED that there be no such file at this time, as 677 their form and function may be defined at a point in the future. For 678 now, URLs should serve simply as class names and be populated by the 679 local deployment administrator. 681 3.13. my-controller 683 This null-valued node signals to the MUD controller to use whatever 684 mapping it has for this MUD-URL to a particular group of hosts. This 685 may require prompting the administrator for class members. Future 686 work should seek to automate membership management. 688 3.14. direction-initiated 690 When applied this matches packets when the flow was initiated in the 691 corresponding direction. [RFC6092] specifies IPv6 guidance best 692 practices. While that document is scoped specifically to IPv6, its 693 contents are applicable for IPv4 as well. When this flag is set, and 694 the system has no reason to believe a flow has been initiated it MUST 695 drop the packet. This node may be implemented in its simplest form 696 by looking at naked SYN bits, but may also be implemented through 697 more stateful mechanisms. 699 4. Processing of the MUD file 701 To keep things relatively simple in addition to whatever definitions 702 exist, we also apply two additional default behaviors: 704 o Anything not explicitly permitted is denied. 706 o Local DNS and NTP are, by default, permitted to and from the 707 Thing. 709 An explicit description of the defaults can be found in Appendix B. 711 5. What does a MUD URL look like? 713 To begin with, MUD takes full advantage of both the https: scheme and 714 the use of .well-known. HTTPS is important in this case because a 715 man in the middle attack could otherwise harm the operation of a 716 class of Things. .well-known is used because we wish to add 717 additional structure to the URL, and want to leave open for future 718 versions both the means by which the URL is processed and the format 719 of the MUD file retrieved (there have already been some discussions 720 along these lines). The URL appears as follows: 722 mud-url = "https://" authority "/.well-known/mud/" mud-rev 723 "/" modelinfo ( "?" extras ) 724 ; authority is from RFC3986 725 mud-rev = "v1" 726 modelinfo = segment ; from RFC3986 727 extras = query ; from RFC3986 729 mud-rev signifies the version of the manufacturer usage description 730 file. This memo specifies "v1" of that file. Later versions may 731 permit additional schemas or modify the format. In order to provide 732 for the broadest compatibility for the various transmission 733 mechanisms, the length of the URL for v1 MUST NOT exceed 255 octets. 735 Taken together with the mud-url, "modelinfo" represents a Thing model 736 as the manufacturer wishes to represent it. It could be a brand name 737 or something more specific. It also may provide a means to indicate 738 what version the product is. Specifically if it has been updated in 739 the field, this is the place where evidence of that update would 740 appear. The field should be changed when the intended communication 741 patterns of a Thing change. While from a controller standpoint, only 742 comparison and matching operations are safe, it is envisioned that 743 updates will require some administrative review. Processing of this 744 URL occurs as specified in [RFC2818] and [RFC3986]. 746 "extras" is intended for use by the MUD controller to provide 747 additional information such as posture about the Thing to the MUD 748 file server. This field MUST NOT be configured on the Thing itself 749 by a manufacturer - that is what "modelinfo" is for. It is left as 750 future work to define the full semantics of this field. 752 6. The MUD YANG Model 754 file "ietf-mud@2017-09-15.yang" 755 module ietf-mud { 756 yang-version 1.1; 757 namespace "urn:ietf:params:xml:ns:yang:ietf-mud"; 758 prefix ietf-mud; 760 import ietf-access-control-list { 761 prefix acl; 762 } 763 import ietf-yang-types { 764 prefix yang; 765 } 766 import ietf-inet-types { 767 prefix inet; 768 } 770 organization 771 "IETF OPSAWG (Ops Area) Working Group"; 772 contact 773 "WG Web: http://tools.ietf.org/wg/opsawg/ 774 WG List: opsawg@ietf.org 775 Author: Eliot Lear 776 lear@cisco.com 777 Author: Ralph Droms 778 rdroms@gmail.com 779 Author: Dan Romascanu 780 dromasca@gmail.com 782 "; 783 description 784 "This YANG module defines a component that augments the 785 IETF description of an access list. This specific module 786 focuses on additional filters that include local, model, 787 and same-manufacturer. 789 This module is intended to be serialized via JSON and stored 790 as a file, as described in RFC XXXX [RFC Editor to fill in with 791 this document #]. 793 Copyright (c) 2016,2017 IETF Trust and the persons 794 identified as the document authors. All rights reserved. 795 Redistribution and use in source and binary forms, with or 796 without modification, is permitted pursuant to, and subject 797 to the license terms contained in, the Simplified BSD 798 License set forth in Section 4.c of the IETF Trust's Legal 799 Provisions Relating to IETF Documents 800 (http://trustee.ietf.org/license-info). 801 This version of this YANG module is part of RFC XXXX; see 802 the RFC itself for full legal notices."; 804 revision 2017-09-15 { 805 description 806 "Initial proposed standard."; 807 reference 808 "RFC XXXX: Manufacturer Usage Description 809 Specification"; 810 } 812 typedef direction { 813 type enumeration { 814 enum "to-device" { 815 description 816 "packets or flows destined to the target 817 Thing"; 818 } 819 enum "from-device" { 820 description 821 "packets or flows destined from 822 the target Thing"; 823 } 824 } 825 description 826 "Which way are we talking about?"; 827 } 829 container mud { 830 presence "Enabled for this particular MUD-URL"; 831 description 832 "MUD related information, as specified 833 by RFC-XXXX [RFC Editor to fill in]."; 834 uses mud-grouping; 835 } 837 grouping mud-grouping { 838 description 839 "Information about when support end(ed), and 840 when to refresh"; 841 leaf mud-url { 842 type inet:uri; 843 mandatory true; 844 description 845 "This is the MUD-URL associated with the entry found 846 in a MUD file."; 847 } 848 leaf last-update { 849 type yang:date-and-time; 850 mandatory true; 851 description 852 "This is intended to be when the current MUD file 853 was generated. MUD Controllers SHOULD NOT check 854 for updates between this time plus cache validity"; 855 } 856 leaf cache-validity { 857 type uint8 { 858 range "1..168"; 859 } 860 units "hours"; 861 default "48"; 862 description 863 "The information retrieved from the MUD server is 864 valid for these many hours, after which it should 865 be refreshed. N.B. MUD controller implementations 866 need not discard MUD files beyond this period."; 867 } 868 leaf masa-server { 869 type inet:uri; 870 description 871 "The URI of the MASA server that network 872 elements should forward requests to for this Thing."; 873 } 874 leaf is-supported { 875 type boolean; 876 mandatory true; 877 description 878 "This boolean indicates whether or not the Thing is 879 currently supported by the manufacturer."; 880 } 881 leaf systeminfo { 882 type inet:uri; 883 description 884 "A URL to a description of this Thing. This 885 should be a brief localized description. The 886 reference text should be no more than octets. 887 systeminfo may be displayed to the user to 888 determine whether to allow the Thing on the 889 network."; 890 } 891 leaf-list extensions { 892 type string { 893 length "1..40"; 894 } 895 description 896 "A list of extension names that are used in this MUD 897 file. Each name is registered with the IANA and 898 described in an RFC."; 899 } 900 container from-device-policy { 901 description 902 "The policies that should be enforced on traffic 903 coming from the device. These policies are not 904 necessarily intended to be enforced at a single 905 point, but may be rendered by the controller to any 906 relevant enorcement points in the network or 907 elsewhere."; 908 uses access-lists; 909 } 910 container to-device-policy { 911 description 912 "The policies that should be enforced on traffic 913 going to the device. These policies are not 914 necessarily intended to be enforced at a single 915 point, but may be rendered by the controller to any 916 relevant enorcement points in the network or 917 elsewhere."; 918 uses access-lists; 919 } 920 } 922 grouping access-lists { 923 description 924 "A grouping for access lists in the context of device 925 policy."; 926 container access-lists { 927 description 928 "The access lists that should be applied to traffic 929 to or from the device."; 930 list access-list { 931 key "acl-name acl-type"; 932 description 933 "Each entry on this list refers to an ACL that 934 should be present in the overall access list 935 data model. Each ACL is identified by name and 936 type."; 937 leaf acl-name { 938 type leafref { 939 path "/acl:access-lists/acl:acl/acl:acl-name"; 940 } 941 description 942 "The name of the ACL for this entry."; 943 } 944 leaf acl-type { 945 type identityref { 946 base acl:acl-base; 947 } 948 description 949 "The type of the ACL for this entry. The name is 950 scoped ONLY to the MUD file, and may not be unique 951 in any other circumstance."; 952 } 953 } 954 } 955 } 957 augment "/acl:access-lists/acl:acl/acl:aces/acl:ace/acl:matches" { 958 description 959 "adding abstractions to avoid need of IP addresses"; 960 container mud-acl { 961 description 962 "MUD-specific matches."; 963 leaf manufacturer { 964 type inet:host; 965 description 966 "A domain that is intended to match the authority 967 section of the MUD-URL. This node is used to specify 968 one or more manufacturers a device should 969 be authorized to access."; 970 } 971 leaf same-manufacturer { 972 type empty; 973 description 974 "This node matches the authority section of the MUD-URL 975 of a Thing. It is intended to grant access to all 976 devices with the same authority section."; 977 } 978 leaf model { 979 type inet:uri; 980 description 981 "Devices of the specified model type will match if 982 they have an identical MUD-URL."; 983 } 984 leaf local-networks { 985 type empty; 986 description 987 "IP addresses will match this node if they are 988 considered local addresses. A local address may be 989 a list of locally defined prefixes and masks 990 that indicate a particular administrative scope."; 991 } 992 leaf controller { 993 type inet:uri; 994 description 995 "This node names a class that has associated with it 996 zero or more IP addresses to match against. These 997 may be scoped to a manufacturer or via a standard 998 URN."; 999 } 1000 leaf my-controller { 1001 type empty; 1002 description 1003 "This node matches one or more network elements that 1004 have been configured to be the controller for this 1005 Thing, based on its MUD-URL."; 1006 } 1007 } 1008 } 1009 augment "/acl:access-lists/acl:acl/acl:aces/" + 1010 "acl:ace/acl:matches/acl:tcp-acl" { 1011 description 1012 "Adding domain names to matching"; 1013 leaf direction-initiated { 1014 type direction; 1015 description 1016 "This node matches based on which direction a 1017 connection was initiated. The means by which that 1018 is determined is discussed in this document."; 1019 } 1020 } 1021 } 1023 1025 7. The Domain Name Extension to the ACL Model 1027 This module specifies an extension to IETF-ACL model such that domain 1028 names may be referenced by augmenting the "matches" node. Different 1029 implementations may deploy differing methods to maintain the mapping 1030 between IP address and domain name, if indeed any are needed. 1031 However, the intent is that resources that are referred to using a 1032 name should be authorized (or not) within an access list. 1034 The structure of the change is as follows: 1036 module: ietf-acldns 1037 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/ 1038 acl:matches/acl:ipv4-acl: 1039 +--rw src-dnsname? inet:host 1040 +--rw dst-dnsname? inet:host 1041 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/ 1042 acl:matches/acl:ipv6-acl: 1043 +--rw src-dnsname? inet:host 1044 +--rw dst-dnsname? inet:host 1046 The choice of these particular points in the access-list model is 1047 based on the assumption that we are in some way referring to IP- 1048 related resources, as that is what the DNS returns. A domain name in 1049 our context is defined in [RFC6991]. The augmentations are 1050 replicated across IPv4 and IPv6 to allow MUD file authors the ability 1051 to control the IP version that the Thing may utilize. 1053 The following node are defined. 1055 7.1. source-dnsname 1057 The argument corresponds to a domain name of a source as specified by 1058 inet:host. A number of means may be used to resolve hosts. What is 1059 important is that such resolutions be consistent with ACLs required 1060 by Things to properly operate. 1062 7.2. destination-dnsname 1064 The argument corresponds to a domain name of a destination as 1065 specified by inet:host See the previous section relating to 1066 resolution. 1068 7.3. The ietf-acldns Model 1070 file "ietf-acldns@2017-09-15.yang" 1071 module ietf-acldns { 1072 yang-version 1.1; 1073 namespace "urn:ietf:params:xml:ns:yang:ietf-acldns"; 1074 prefix "ietf-acldns"; 1076 import ietf-access-control-list { 1077 prefix "acl"; 1078 } 1080 import ietf-inet-types { 1081 prefix "inet"; 1082 } 1083 organization 1084 "IETF OPSAWG (Ops Area) Working Group"; 1086 contact 1087 "WG Web: http://tools.ietf.org/wg/opsawg/ 1088 WG List: opsawg@ietf.org 1089 Author: Eliot Lear 1090 lear@cisco.com 1091 Author: Ralph Droms 1092 rdroms@gmail.com 1093 Author: Dan Romascanu 1094 dromasca@gmail.com 1095 "; 1097 description 1098 "This YANG module defines a component that augments the 1099 IETF description of an access list to allow dns names 1100 as matching criteria."; 1102 revision "2017-09-15" { 1103 description "Base version of dnsname extension of ACL model"; 1104 reference "RFC XXXX: Manufacturer Usage Description 1105 Specification"; 1106 } 1108 grouping dns-matches { 1109 description "Domain names for matching."; 1111 leaf src-dnsname { 1112 type inet:host; 1113 description "domain name to be matched against"; 1114 } 1115 leaf dst-dnsname { 1116 type inet:host; 1117 description "domain name to be matched against"; 1118 } 1119 } 1121 augment "/acl:access-lists/acl:acl/acl:aces/acl:ace/" + 1122 "acl:matches/acl:ipv4-acl" { 1123 description "Adding domain names to matching"; 1124 uses dns-matches; 1125 } 1127 augment "/acl:access-lists/acl:acl/" + 1128 "acl:aces/acl:ace/" + 1129 "acl:matches/acl:ipv6-acl" { 1130 description "Adding domain names to matching"; 1131 uses dns-matches; 1132 } 1133 } 1134 1136 8. MUD File Example 1138 This example contains two access lists that are intended to provide 1139 outbound access to a cloud service on TCP port 443. 1141 { 1142 "ietf-mud:mud": { 1143 "mud-url": "https://bms.example.com/.well-known/mud/v1/lightbulb2000", 1144 "last-update": "2017-09-07T13:47:52+02:00", 1145 "systeminfo": "https://bms.example.com/descriptions/lightbulb2000", 1146 "cache-validity": 48, 1147 "from-device-policy": { 1148 "access-lists": { 1149 "access-list": [ 1150 { 1151 "acl-name": "mud-83312-v6fr", 1152 "acl-type": "ietf-access-control-list:ipv6-acl" 1153 } 1154 ] 1155 } 1156 }, 1157 "to-device-policy": { 1158 "access-lists": { 1159 "access-list": [ 1160 { 1161 "acl-name": "mud-83312-v6to", 1162 "acl-type": "ietf-access-control-list:ipv6-acl" 1163 } 1164 ] 1165 } 1166 } 1167 }, 1168 "ietf-access-control-list:access-lists": { 1169 "acl": [ 1170 { 1171 "acl-name": "mud-83312-v6to", 1172 "acl-type": "ipv6-acl", 1173 "access-list-entries": { 1174 "ace": [ 1175 { 1176 "rule-name": "cl0-todev", 1177 "matches": { 1178 "ipv6-acl": { 1179 "ietf-acldns:src-dnsname": "service.bms.example.com" 1180 }, 1181 "protocol": 6, 1182 "source-port-range": { 1183 "lower-port": 443, 1184 "upper-port": 443 1185 }, 1186 "tcp-acl": { 1187 "ietf-mud:direction-initiated": "from-device" 1188 } 1189 }, 1190 "actions": { 1191 "permit": [ 1192 null 1193 ] 1194 } 1195 } 1196 ] 1197 } 1198 }, 1199 { 1200 "acl-name": "mud-83312-v6fr", 1201 "acl-type": "ipv6-acl", 1202 "access-list-entries": { 1203 "ace": [ 1204 { 1205 "rule-name": "cl0-frdev", 1206 "matches": { 1207 "ipv6-acl": { 1208 "ietf-acldns:dst-dnsname": "service.bms.example.com" 1209 }, 1210 "protocol": 6, 1211 "destination-port-range": { 1212 "lower-port": 443, 1213 "upper-port": 443 1214 }, 1215 "tcp-acl": { 1216 "ietf-mud:direction-initiated": "from-device" 1217 } 1218 }, 1219 "actions": { 1220 "permit": [ 1221 null 1222 ] 1223 } 1224 } 1225 ] 1227 } 1228 } 1229 ] 1230 } 1231 } 1233 In this example, two policies are declared, one from the Thing and 1234 the other to the Thing. Each policy names an access list that 1235 applies to the Thing, and one that applies from. Within each access 1236 list, access is permitted to packets flowing to or from the Thing 1237 that can be mapped to the domain name of "service.bms.example.com". 1238 For each access list, the enforcement point should expect that the 1239 thing initiated the connection. 1241 9. The MUD URL DHCP Option 1243 The IPv4 MUD URL client option has the following format: 1245 +------+-----+------------------------------ 1246 | code | len | MUD URL 1247 +------+-----+------------------------------ 1249 Code OPTION_MUD_URL_V4 (161) is assigned by IANA. len is a single 1250 octet that indicates the length of the URL in octets. MUD URL is a 1251 URL. MUD URLs MUST NOT exceed 255 octets. 1253 The IPv6 MUD URL client option has the following format: 1255 0 1 2 3 1256 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 1257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1258 | OPTION_MUD_URL_V6 | option-length | 1259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1260 | MUD URL | 1261 | ... | 1262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1264 OPTION_MUD_URL_V6 (112; assigned by IANA). 1266 option-length contains the length of the URL in octets. 1268 The intent of this option is to provide both a new Thing classifier 1269 to the network as well as some recommended configuration to the 1270 routers that implement policy. However, it is entirely the purview 1271 of the network system as managed by the network administrator to 1272 decide what to do with this information. The key function of this 1273 option is simply to identify the type of Thing to the network in a 1274 structured way such that the policy can be easily found with existing 1275 toolsets. 1277 9.1. Client Behavior 1279 A DHCPv4 client MAY emit a DHCPv4 option and a DHCPv6 client MAY emit 1280 DHCPv6 option. These options are singletons, as specified in 1281 [RFC7227]. Because clients are intended to have at most one MUD URL 1282 associated with them, they may emit at most one MUD URL option via 1283 DHCPv4 and one MUD URL option via DHCPv6. In the case where both v4 1284 and v6 DHCP options are emitted, the same URL MUST be used. 1286 Clients SHOULD log or otherwise report improper acknowledgments from 1287 servers, but they MUST NOT modify their MUD URL configuration based 1288 on a server's response. The server's response is only an 1289 acknowledgment that the server has processed the option, and promises 1290 no specific network behavior to the client. In particular, it may 1291 not be possible for the server to retrieve the file associated with 1292 the MUD URL, or the local network administration may not wish to use 1293 the usage description. Neither of these situations should be 1294 considered in any way exceptional. 1296 9.2. Server Behavior 1298 A DHCP server may ignore these options or take action based on 1299 receipt of these options. If a server successfully parses the option 1300 and the URL, it MUST return the option with length field set to zero 1301 and a corresponding null URL field as an acknowledgment. Even in 1302 this circumstance, no specific network behavior is guaranteed. When 1303 a server consumes this option, it will either forward the URL and 1304 relevant client information (such as the gateway address or giaddr) 1305 to a network management system, or it will retrieve the usage 1306 description itself by resolving the URL. 1308 DHCP servers may implement MUD functionality themselves or they may 1309 pass along appropriate information to a network management system or 1310 MUD controller. A DHCP server that does process the MUD URL MUST 1311 adhere to the process specified in [RFC2818] and [RFC5280] to 1312 validate the TLS certificate of the web server hosting the MUD file. 1313 Those servers will retrieve the file, process it, create and install 1314 the necessary configuration on the relevant network element. Servers 1315 SHOULD monitor the gateway for state changes on a given interface. A 1316 DHCP server that does not provide MUD functionality and has forwarded 1317 a MUD URL to a MUD controller MUST notify the MUD controller of any 1318 corresponding change to the DHCP state of the client (such as 1319 expiration or explicit release of a network address lease). 1321 9.3. Relay Requirements 1323 There are no additional requirements for relays. 1325 10. The Manufacturer Usage Description (MUD) URL X.509 Extension 1327 This section defines an X.509 non-critical certificate extension that 1328 contains a single Uniform Resource Locator (URL) that points to an 1329 on-line Manufacturer Usage Description concerning the certificate 1330 subject. URI must be represented as described in Section 7.4 of 1331 [RFC5280]. 1333 Any Internationalized Resource Identifiers (IRIs) MUST be mapped to 1334 URIs as specified in Section 3.1 of [RFC3987] before they are placed 1335 in the certificate extension. 1337 The semantics of the URL are defined Section 5 of this document. 1339 The choice of id-pe is based on guidance found in Section 4.2.2 of 1340 [RFC5280]: 1342 These extensions may be used to direct applications to on-line 1343 information about the issuer or the subject. 1345 The MUD URL is precisely that: online information about the 1346 particular subject. 1348 The new extension is identified as follows: 1350 1352 MUDURLExtnModule-2016 { iso(1) identified-organization(3) dod(6) 1353 internet(1) security(5) mechanisms(5) pkix(7) 1354 id-mod(0) id-mod-mudURLExtn2016(88) } 1356 DEFINITIONS IMPLICIT TAGS ::= BEGIN 1358 -- EXPORTS ALL -- 1360 IMPORTS 1361 EXTENSION 1362 FROM PKIX-CommonTypes-2009 1363 { iso(1) identified-organization(3) dod(6) internet(1) 1364 security(5) mechanisms(5) pkix(7) id-mod(0) 1365 id-mod-pkixCommon-02(57) } 1367 id-pe 1368 FROM PKIX1Explicit-2009 1369 { iso(1) identified-organization(3) dod(6) internet(1) 1370 security(5) mechanisms(5) pkix(7) id-mod(0) 1371 id-mod-pkix1-explicit-02(51) } ; 1372 MUDCertExtensions EXTENSION ::= { ext-MUDURL, ... } 1373 ext-MUDURL EXTENSION ::= { SYNTAX MUDURLSyntax 1374 IDENTIFIED BY id-pe-mud-url } 1376 id-pe-mud-url OBJECT IDENTIFIER ::= { id-pe 25 } 1378 MUDURLSyntax ::= IA5String 1380 END 1382 1384 While this extension can appear in either an 802.AR manufacturer 1385 certificate (IDevID) or deployment certificate (LDevID), of course it 1386 is not guaranteed in either, nor is it guaranteed to be carried over. 1387 It is RECOMMENDED that MUD controller implementations maintain a 1388 table that maps a Thing to its MUD-URL based on IDevIDs. 1390 11. The Manufacturer Usage Description LLDP extension 1392 The IEEE802.1AB Link Layer Discovery Protocol (LLDP) is a one hop 1393 vendor-neutral link layer protocol used by end hosts network Things 1394 for advertising their identity, capabilities, and neighbors on an 1395 IEEE 802 local area network. Its Type-Length-Value (TLV) design 1396 allows for 'vendor-specific' extensions to be defined. IANA has a 1397 registered IEEE 802 organizationally unique identifier (OUI) defined 1398 as documented in [RFC7042]. The MUD LLDP extension uses a subtype 1399 defined in this document to carry the MUD URL. 1401 The LLDP vendor specific frame has the following format: 1403 +--------+--------+----------+---------+-------------- 1404 |TLV Type| len | OUI |subtype | MUD URL 1405 | =127 | |= 00 00 5E| = 1 | 1406 |(7 bits)|(9 bits)|(3 octets)|(1 octet)|(1-255 octets) 1407 +--------+--------+----------+---------+-------------- 1409 where: 1411 o TLV Type = 127 indicates a vendor-specific TLV 1413 o len - indicates the TLV string length 1415 o OUI = 00 00 5E is the organizationally unique identifier of IANA 1417 o subtype = 1 (to be assigned by IANA for the MUD URL) 1419 o MUD URL - the length MUST NOT exceed 255 octets 1421 The intent of this extension is to provide both a new Thing 1422 classifier to the network as well as some recommended configuration 1423 to the routers that implement policy. However, it is entirely the 1424 purview of the network system as managed by the network administrator 1425 to decide what to do with this information. The key function of this 1426 extension is simply to identify the type of Thing to the network in a 1427 structured way such that the policy can be easily found with existing 1428 toolsets. 1430 Hosts, routers, or other network Things that implement this option 1431 are intended to have at most one MUD URL associated with them, so 1432 they may transmit at most one MUD URL value. 1434 Hosts, routers, or other network Things that implement this option 1435 may ignore these options or take action based on receipt of these 1436 options. For example they may fill in information in the respective 1437 extensions of the LLDP Management Information Base (LLDP MIB). LLDP 1438 operates in a one-way direction. LLDPDUs are not exchanged as 1439 information requests by one Thing and response sent by another Thing. 1440 The other Things do not acknowledge LLDP information received from a 1441 Thing. No specific network behavior is guaranteed. When a Thing 1442 consumes this extension, it may either forward the URL and relevant 1443 remote Thing information to a MUD controller, or it will retrieve the 1444 usage description by resolving the URL in accordance with normal HTTP 1445 semantics. 1447 12. Creating and Processing of Signed MUD Files 1449 Because MUD files contain information that may be used to configure 1450 network access lists, they are sensitive. To insure that they have 1451 not been tampered with, it is important that they be signed. We make 1452 use of DER-encoded Cryptographic Message Syntax (CMS) [RFC5652] for 1453 this purpose. 1455 12.1. Creating a MUD file signature 1457 A MUD file MUST be signed using CMS as an opaque binary object. In 1458 order to make successful verification more likely, intermediate 1459 certificates SHOULD be included. The signature is stored at the same 1460 location as the MUD URL but with the suffix of ".p7s". Signatures 1461 are transferred using content-type "application/pkcs7-signature". 1463 For example: 1465 % openssl cms -sign -signer mancertfile -inkey mankey \ 1466 -in mudfile -binary -outform DER - \ 1467 -certfile intermediatecert -out mudfile.p7s 1469 Note: A MUD file may need to be re-signed if the signature expires. 1471 12.2. Verifying a MUD file signature 1473 Prior to retrieving a MUD file the MUD controller SHOULD retrieve the 1474 MUD signature file using the MUD URL with a suffix of ".p7s". For 1475 example, if the MUD URL is "https://example.com/.well-known/v1/ 1476 modela", the MUD signature URL will be "https://example.com/.well- 1477 known/v1/modela.p7s". 1479 Upon retrieving a MUD file, a MUD controller MUST validate the 1480 signature of the file before continuing with further processing. A 1481 MUD controller MUST cease processing of that file it cannot validate 1482 the chain of trust to a known trust anchor until an administrator has 1483 given approval. 1485 The purpose of the signature on the file is to assign accountability 1486 to an entity, whose reputation can be used to guide administrators on 1487 whether or not to accept a given MUD file. It is already common 1488 place to check web reputation on the location of a server on which a 1489 file resides. While it is likely that the manufacturer will be the 1490 signer of the file, this is not strictly necessary, and may not be 1491 desirable. For one thing, in some environments, integrators may 1492 install their own certificates. For another, what is more important 1493 is the accountability of the recommendation, and not the 1494 cryptographic relationship between the device and the file. 1496 An example: 1498 % openssl cms -verify -in mudfile.p7s -inform DER -content mudfile 1500 Note the additional step of verifying the common trust root. 1502 13. Extensibility 1504 One of our design goals is to see that MUD files are able to be 1505 understood by as broad a cross-section of systems as is possible. 1506 Coupled with the fact that we have also chosen to leverage existing 1507 mechanisms, we are left with no ability to negotiate extensions and a 1508 limited desire for those extensions in any event. A such, a two-tier 1509 extensibility framework is employed, as follows: 1511 1. At a coarse grain, a protocol version is included in a MUD URL. 1512 This memo specifies MUD version 1. Any and all changes are 1513 entertained when this version is bumped. Transition approaches 1514 between versions would be a matter for discussion in future 1515 versions. 1517 2. At a finer grain, only extensions that would not incur additional 1518 risk to the Thing are permitted. Specifically, adding nodes to 1519 the mud container is permitted with the understanding that such 1520 additions will be ignored by unaware implementations. Any such 1521 extensions SHALL be standardized through the IETF process, and 1522 MUST be named in the "extensions" list. MUD controllers MUST 1523 ignore YANG nodes they do not understand and SHOULD create an 1524 exception to be resolved by an administrator, so as to avoid any 1525 policy inconsistencies. 1527 14. Deployment Considerations 1529 Because MUD consists of a number of architectural building blocks, it 1530 is possible to assemble different deployment scenarios. One key 1531 aspect is where to place policy enforcement. In order to protect the 1532 Thing from other Things within a local deployment, policy can be 1533 enforced on the nearest switch or access point. In order to limit 1534 unwanted traffic within a network, it may also be advisable to 1535 enforce policy as close to the Internet as possible. In some 1536 circumstances, policy enforcement may not be available at the closest 1537 hop. At that point, the risk of so-called east-west infection is 1538 increased to the number of Things that are able to communicate 1539 without protection. 1541 A caution about some of the classes: admission of a Thing into the 1542 "manufacturer" and "same-manufacturer" class may have impact on 1543 access of other Things. Put another way, the admission may grow the 1544 access-list on switches connected to other Things, depending on how 1545 access is managed. Some care should be given on managing that 1546 access-list growth. Alternative methods such as additional network 1547 segmentation can be used to keep that growth within reason. 1549 15. Security Considerations 1551 Based on how a MUD-URL is emitted, a Thing may be able to lie about 1552 what it is, thus gaining additional network access. There are 1553 several means to limit risk in this case. The most obvious is to 1554 only believe Things that make use of certificate-based authentication 1555 such as IEEE 802.1AR certificates. When those certificates are not 1556 present, Things claiming to be of a certain manufacturer SHOULD NOT 1557 be included in that manufacturer grouping without additional 1558 validation of some form. This will occur when it makes use of 1559 primitives such as "manufacturer" for the purpose of accessing Things 1560 of a particular type. Similarly, network management systems may be 1561 able to fingerprint the Thing. In such cases, the MUD-URL can act as 1562 a classifier that can be proven or disproven. Fingerprinting may 1563 have other advantages as well: when 802.1AR certificates are used, 1564 because they themselves cannot change, fingerprinting offers the 1565 opportunity to add artificats to the MUD-URL. The meaning of such 1566 artifacts is left as future work. 1568 Network management systems SHOULD NOT accept a usage description for 1569 a Thing with the same MAC address that has indicated a change of 1570 authority without some additional validation (such as review by a 1571 network administrator). New Things that present some form of 1572 unauthenticated MUD URL SHOULD be validated by some external means 1573 when they would be otherwise be given increased network access. 1575 It may be possible for a rogue manufacturer to inappropriately 1576 exercise the MUD file parser, in order to exploit a vulnerability. 1577 There are three recommended approaches to address this threat. The 1578 first is to validate the signature of the MUD file. The second is to 1579 have a system do a primary scan of the file to ensure that it is both 1580 parseable and believable at some level. MUD files will likely be 1581 relatively small, to start with. The number of ACEs used by any 1582 given Thing should be relatively small as well. It may also be 1583 useful to limit retrieval of MUD URLs to only those sites that are 1584 known to have decent web or domain reputations. 1586 Use of a URL necessitates the use of domain names. If a domain name 1587 changes ownership, the new owner of that domain may be able to 1588 provide MUD files that MUD controllers would consider valid. There 1589 are a few approaches that can mitigate this attack. First, MUD 1590 controllers SHOULD cache certificates used by the MUD file server. 1591 When a new certificate is retrieved for whatever reason, the MUD 1592 controller should check to see if ownership of the domain has 1593 changed. A fair programmatic approximation of this is when the name 1594 servers for the domain have changed. If the actual MUD file has 1595 changed, the controller MAY check the WHOIS database to see if 1596 registration ownership of a domain has changed. If a change has 1597 occured, or if for some reason it is not possible to determine 1598 whether ownership has changed, further review may be warranted. 1599 Note, this remediation does not take into account the case of a Thing 1600 that was produced long ago and only recently fielded, or the case 1601 where a new MUD controller has been installed. 1603 It may not be possible for a MUD controller to retrieve a MUD file at 1604 any given time. Should a MUD controller fail to retrieve a MUD file, 1605 it SHOULD consider the existing one safe to use, at least for a time. 1606 After some period, it SHOULD log that it has been unable to retrieve 1607 the file. There may be very good reasons for such failures, 1608 including the possibility that the MUD controller is in an off-line 1609 environment, the local Internet connection has failed, or the remote 1610 Internet connection has failed. It is also possible that an attacker 1611 is attempting to prevent onboarding of a device. It is a local 1612 deployment decision as to whether or not devices may be onboarded in 1613 the face of such failures. 1615 The release of a MUD URL by a Thing reveals what the Thing is, and 1616 provides an attacker with guidance on what vulnerabilities may be 1617 present. 1619 While the MUD URL itself is not intended to be unique to a specific 1620 Thing, the release of the URL may aid an observer in identifying 1621 individuals when combined with other information. This is a privacy 1622 consideration. 1624 In addressing both of these concerns, implementors should take into 1625 account what other information they are advertising through 1626 mechanisms such as mDNS[RFC6872], how a Thing might otherwise be 1627 identified, perhaps through how it behaves when it is connected to 1628 the network, whether a Thing is intended to be used by individuals or 1629 carry personal identifying information, and then apply appropriate 1630 data minimization techniques. One approach is to make use of TEAP 1631 [RFC7170] as the means to share information with authorized 1632 components in the network. Network Things may also assist in 1633 limiting access to the MUD-URL through the use of mechanisms such as 1634 DHCPv6-Shield [RFC7610]. 1636 Please note that the security considerations mentioned in Section 4.7 1637 of [I-D.ietf-netmod-rfc6087bis] are not applicable in this case 1638 because the YANG serialization is not intended to be accessed via 1639 NETCONF. However, for those who try to instantiate this model in a 1640 Thing via NETCONF, all objects in each model in this draft exhibit 1641 similar security characteristics as [I-D.ietf-netmod-acl-model]. The 1642 basic purpose of MUD is to configure access, and so by its very 1643 nature can be disruptive if used by unauthorized parties. 1645 16. IANA Considerations 1647 16.1. YANG Module Registrations 1649 The following YANG modules are requested to be registred in the "IANA 1650 Module Names" registry: 1652 The ietf-mud module: 1654 o Name: ietf-mud 1656 o XML Namespace: urn:ietf:params:xml:ns:yang:ietf-mud 1658 o Prefix: ief-mud 1660 o Reference: This memo 1662 The ietf-acldns module: 1664 o Name: ietf-acldns 1666 o XML Namespace: urn:ietf:params:xml:ns:yang:ietf-acldns 1668 o Prefix: ietf-acldns 1670 o Reference: This memo 1672 16.2. DHCPv4 and DHCPv6 Options 1674 The IANA has allocated option 161 in the Dynamic Host Configuration 1675 Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry 1676 for the MUD DHCPv4 option. 1678 IANA is requested to allocated the DHCPv4 and v6 options as specified 1679 in Section 9. 1681 16.3. PKIX Extensions 1683 IANA is kindly requested to make the following assignments for: 1685 o The MUDURLExtnModule-2016 ASN.1 module in the "SMI Security for 1686 PKIX Module Identifier" registry (1.3.6.1.5.5.7.0). 1688 o id-pe-mud-url object identifier from the "SMI Security for PKIX 1689 Certificate Extension" registry (1.3.6.1.5.5.7.1). 1691 The use fo these values is specified in Section 10. 1693 16.4. Well Known URI Suffix 1695 The IANA has allocated the URL suffix of "mud" as follows: 1697 o URI Suffix: "mud" o Specification documents: this document o 1698 Related information: n/a 1700 16.5. MIME Media-type Registration for MUD files 1702 The following media-type is defined for transfer of MUD file: 1704 o Type name: application 1705 o Subtype name: mud+json 1706 o Required parameters: n/a 1707 o Optional parameters: n/a 1708 o Encoding considerations: 8bit; application/mud+json values 1709 are represented as a JSON object; UTF-8 encoding SHOULD be 1710 employed. 1711 o Security considerations: See {{secon}} of this document. 1712 o Interoperability considerations: n/a 1713 o Published specification: this document 1714 o Applications that use this media type: MUD controllers as 1715 specified by this document. 1716 o Fragment identifier considerations: n/a 1717 o Additional information: 1719 Magic number(s): n/a 1720 File extension(s): n/a 1721 Macintosh file type code(s): n/a 1723 o Person & email address to contact for further information: 1724 Eliot Lear , Ralph Droms 1725 o Intended usage: COMMON 1726 o Restrictions on usage: none 1727 o Author: 1728 Eliot Lear 1729 Ralph Droms 1730 o Change controller: IESG 1731 o Provisional registration? (standards tree only): No. 1733 16.6. LLDP IANA TLV Subtype Registry 1735 IANA is requested to create a new registry for IANA Link Layer 1736 Discovery Protocol (LLDP) TLV subtype values. The recommended policy 1737 for this registry is Expert Review. The maximum number of entries in 1738 the registry is 256. 1740 IANA is required to populate the initial registry with the value: 1742 LLDP subtype value = 1 (All the other 255 values should be initially 1743 marked as 'Unassigned'.) 1745 Description = the Manufacturer Usage Description (MUD) Uniform 1746 Resource Locator (URL) 1748 Reference = < this document > 1750 16.7. The MUD Well Known Universal Resource Name (URNs) 1752 The following parameter registry is requested to be added in 1753 accordance with [RFC3553] 1755 Registry name: "urn:ietf:params:mud" is requested. 1756 Specification: this document 1757 Repository: this document 1758 Index value: Encoded identically to a TCP/UDP port service 1759 name, as specified in Section 5.1 of [RFC6335] 1761 The following entries should be added to the "urn:ietf:params:mud" 1762 name space: 1764 "urn:ietf:params:mud:dns" refers to the service specified by 1765 [RFC1123]. "urn:ietf:params:mud:ntp" refers to the service specified 1766 by [RFC5905]. 1768 16.8. Extensions Registry 1770 The IANA is requested to establish a registry of extensions as 1771 follows: 1773 Registry name: MUD extensions registry 1774 Registry policy: Standards action 1775 Standard reference: document 1776 Extension name: UTF-8 encoded string, not to exceed 40 characters. 1778 Each extension MUST follow the rules specified in this specification. 1779 As is usual, the IANA issues early allocations based in accordance 1780 with [RFC7120]. 1782 17. Acknowledgments 1784 The authors would like to thank Einar Nilsen-Nygaard, who 1785 singlehandedly updated the model to match the updated ACL model, 1786 Bernie Volz, Tom Gindin, Brian Weis, Sandeep Kumar, Thorsten Dahm, 1787 John Bashinski, Steve Rich, Jim Bieda, Dan Wing, Joe Clarke, Henk 1788 Birkholz, Adam Montville, and Robert Sparks for their valuable advice 1789 and reviews. Russ Housley entirely rewrote Section 10 to be a 1790 complete module. Adrian Farrel provided the basis for privacy 1791 considerations text. Kent Watson provided a thorough review of the 1792 architecture and the YANG model. The remaining errors in this work 1793 are entirely the responsibility of the authors. 1795 18. References 1797 18.1. Normative References 1799 [I-D.ietf-anima-bootstrapping-keyinfra] 1800 Pritikin, M., Richardson, M., Behringer, M., Bjarnason, 1801 S., and K. Watsen, "Bootstrapping Remote Secure Key 1802 Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- 1803 keyinfra-07 (work in progress), July 2017. 1805 [I-D.ietf-netmod-acl-model] 1806 Jethanandani, M., Huang, L., Agarwal, S., and D. Blair, 1807 "Network Access Control List (ACL) YANG Data Model", 1808 draft-ietf-netmod-acl-model-13 (work in progress), 1809 September 2017. 1811 [IEEE8021AB] 1812 Institute for Electrical and Electronics Engineers, "IEEE 1813 Standard for Local and Metropolitan Area Networks-- 1814 Station and Media Access Control Connectivity Discovery", 1815 n.d.. 1817 [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - 1818 Application and Support", STD 3, RFC 1123, 1819 DOI 10.17487/RFC1123, October 1989, . 1822 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1823 Requirement Levels", BCP 14, RFC 2119, 1824 DOI 10.17487/RFC2119, March 1997, . 1827 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 1828 RFC 2131, DOI 10.17487/RFC2131, March 1997, 1829 . 1831 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 1832 DOI 10.17487/RFC2818, May 2000, . 1835 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1836 C., and M. Carney, "Dynamic Host Configuration Protocol 1837 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1838 2003, . 1840 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 1841 Levkowetz, Ed., "Extensible Authentication Protocol 1842 (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004, 1843 . 1845 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1846 Resource Identifier (URI): Generic Syntax", STD 66, 1847 RFC 3986, DOI 10.17487/RFC3986, January 2005, 1848 . 1850 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource 1851 Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987, 1852 January 2005, . 1854 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1855 Housley, R., and W. Polk, "Internet X.509 Public Key 1856 Infrastructure Certificate and Certificate Revocation List 1857 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, 1858 . 1860 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 1861 RFC 5652, DOI 10.17487/RFC5652, September 2009, 1862 . 1864 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 1865 "Network Time Protocol Version 4: Protocol and Algorithms 1866 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 1867 . 1869 [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for 1870 the Network Configuration Protocol (NETCONF)", RFC 6020, 1871 DOI 10.17487/RFC6020, October 2010, . 1874 [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. 1875 Cheshire, "Internet Assigned Numbers Authority (IANA) 1876 Procedures for the Management of the Service Name and 1877 Transport Protocol Port Number Registry", BCP 165, 1878 RFC 6335, DOI 10.17487/RFC6335, August 2011, 1879 . 1881 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", 1882 RFC 6991, DOI 10.17487/RFC6991, July 2013, 1883 . 1885 [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code 1886 Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January 1887 2014, . 1889 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 1890 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 1891 BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014, 1892 . 1894 [RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield: 1895 Protecting against Rogue DHCPv6 Servers", BCP 199, 1896 RFC 7610, DOI 10.17487/RFC7610, August 2015, 1897 . 1899 18.2. Informative References 1901 [FW95] Chapman, D. and E. Zwicky, "Building Internet Firewalls", 1902 January 1995. 1904 [I-D.ietf-netmod-rfc6087bis] 1905 Bierman, A., "Guidelines for Authors and Reviewers of YANG 1906 Data Model Documents", draft-ietf-netmod-rfc6087bis-14 1907 (work in progress), September 2017. 1909 [IEEE8021AR] 1910 Institute for Electrical and Electronics Engineers, 1911 "Secure Device Identity", 1998. 1913 [ISO.8601.1988] 1914 International Organization for Standardization, "Data 1915 elements and interchange formats - Information interchange 1916 - Representation of dates and times", ISO Standard 8601, 1917 June 1988. 1919 [RFC1984] IAB and IESG, "IAB and IESG Statement on Cryptographic 1920 Technology and the Internet", BCP 200, RFC 1984, 1921 DOI 10.17487/RFC1984, August 1996, . 1924 [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: 1925 Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, 1926 . 1928 [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An 1929 IETF URN Sub-namespace for Registered Protocol 1930 Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June 1931 2003, . 1933 [RFC6092] Woodyatt, J., Ed., "Recommended Simple Security 1934 Capabilities in Customer Premises Equipment (CPE) for 1935 Providing Residential IPv6 Internet Service", RFC 6092, 1936 DOI 10.17487/RFC6092, January 2011, . 1939 [RFC6872] Gurbani, V., Ed., Burger, E., Ed., Anjali, T., Abdelnur, 1940 H., and O. Festor, "The Common Log Format (CLF) for the 1941 Session Initiation Protocol (SIP): Framework and 1942 Information Model", RFC 6872, DOI 10.17487/RFC6872, 1943 February 2013, . 1945 [RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and 1946 IETF Protocol and Documentation Usage for IEEE 802 1947 Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042, 1948 October 2013, . 1950 [RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna, 1951 "Tunnel Extensible Authentication Protocol (TEAP) Version 1952 1", RFC 7170, DOI 10.17487/RFC7170, May 2014, 1953 . 1955 [RFC7452] Tschofenig, H., Arkko, J., Thaler, D., and D. McPherson, 1956 "Architectural Considerations in Smart Object Networking", 1957 RFC 7452, DOI 10.17487/RFC7452, March 2015, 1958 . 1960 [RFC7488] Boucadair, M., Penno, R., Wing, D., Patil, P., and T. 1961 Reddy, "Port Control Protocol (PCP) Server Selection", 1962 RFC 7488, DOI 10.17487/RFC7488, March 2015, 1963 . 1965 Appendix A. Changes from Earlier Versions 1967 RFC Editor to remove this section prior to publication. 1969 Draft -09 to -10: 1971 o AD input. 1973 o Correct dates. 1975 o Add compliance sentence as to which ACL module features are 1976 implemented. 1978 Draft -08 to -09: 1980 o Resolution of Security Area review, IoT directorate review, GenART 1981 review, YANG doctors review. 1983 o change of YANG structure to address mandatory nodes. 1985 o Terminology cleanup. 1987 o specify out extra portion of MUD-URL. 1989 o consistency changes. 1991 o improved YANG descriptions. 1993 o Remove extra revisions. 1995 o Track ACL model changes. 1997 o Additional cautions on use of ACL model; further clarifications on 1998 extensions. 2000 Draft -07 to -08: 2002 o a number of editorials corrected. 2004 o definition of MUD file tweaked. 2006 Draft -06 to -07: 2008 o Examples updated. 2010 o Additional clarification for direction-initiated. 2012 o Additional implementation guidance given. 2014 Draft -06 to -07: 2016 o Update models to match new ACL model 2018 o extract directionality from the ACL, introducing a new device 2019 container. 2021 Draft -05 to -06: 2023 o Make clear that this is a component architecture (Polk and Watson) 2025 o Add order of operations (Watson) 2027 o Add extensions leaf-list (Pritikin) 2028 o Remove previous-mud-file (Watson) 2030 o Modify text in last-update (Watson) 2032 o Clarify local networks (Weis, Watson) 2034 o Fix contact info (Watson) 2036 o Terminology clarification (Weis) 2038 o Advice on how to handle LDevIDs (Watson) 2040 o Add deployment considerations (Watson) 2042 o Add some additional text about fingerprinting (Watson) 2044 o Appropriate references to 6087bis (Watson) 2046 o Change systeminfo to a URL to be referenced (Lear) 2048 Draft -04 to -05: * syntax error correction 2050 Draft -03 to -04: * Re-add my-controller 2052 Draft -02 to -03: * Additional IANA updates * Format correction in 2053 YANG. * Add reference to TEAP. 2055 Draft -01 to -02: * Update IANA considerations * Accept Russ Housley 2056 rewrite of X.509 text * Include privacy considerations text * Redo 2057 the URL limit. Still 255 bytes, but now stated in the URL 2058 definition. * Change URI registration to be under urn:ietf:params 2060 Draft -00 to -01: * Fix cert trust text. * change supportInformation 2061 to meta-info * Add an informational element in. * add urn registry 2062 and create first entry * add default elements 2064 Appendix B. Default MUD nodes 2066 What follows is a MUD file that permits DNS traffic to a controller 2067 that is registered with the URN "urn:ietf:params:mud:dns" and traffic 2068 NTP to a controller that is registered "urn:ietf:params:mud:ntp". 2069 This is considered the default behavior and the ACEs are in effect 2070 appended to whatever other ACEs. To block DNS or NTP one repeats the 2071 matching statement but replace "permit" with deny. Because ACEs are 2072 processed in the order they are received, the defaults would not be 2073 reached. A MUD controller might further decide to optimize to simply 2074 not include the defaults when they are overriden. 2076 The access-list component of the MUD entry is included below. 2078 { 2079 "ietf-access-control-list:access-lists": { 2080 "acl": [ 2081 { 2082 "acl-name": "mud-67390-v4to", 2083 "acl-type": "ipv4-acl", 2084 "aces": { 2085 "ace": [ 2086 { 2087 "rule-name": "ent0-todev", 2088 "matches": { 2089 "ietf-mud:mud-acl"{ 2090 "controller": "urn:ietf:params:mud:dns" 2091 }, 2092 "protocol": 17, 2093 "source-port-range": { 2094 "lower-port": 53, 2095 "upper-port": 53 2096 } 2097 }, 2098 "actions": { 2099 "permit": [ 2100 null 2101 ] 2102 } 2103 }, 2104 { 2105 "rule-name": "ent1-todev", 2106 "matches": { 2107 "ietf-mud:mud-acl"{ 2108 "controller": "urn:ietf:params:mud:ntp" 2109 }, 2110 "protocol": 17 2111 }, 2112 "actions": { 2113 "permit": [ 2114 null 2115 ] 2116 } 2117 } 2118 ] 2119 } 2120 }, 2121 { 2122 "acl-name": "mud-67390-v4fr", 2123 "acl-type": "ipv4-acl", 2124 "access-list-entries": { 2125 "ace": [ 2126 { 2127 "rule-name": "ent0-frdev", 2128 "matches": { 2129 "ietf-mud:mud-acl"{ 2130 "controller": "urn:ietf:params:mud:dns" 2131 }, 2132 "protocol": 17, 2133 "destination-port-range": { 2134 "lower-port": 53, 2135 "upper-port": 53 2136 } 2137 }, 2138 "actions": { 2139 "permit": [ 2140 null 2141 ] 2142 } 2143 }, 2144 { 2145 "rule-name": "ent1-frdev", 2146 "matches": { 2147 "ietf-mud:mud-acl"{ 2148 "controller": "urn:ietf:params:mud:ntp" 2149 }, 2150 "protocol": 17 2151 }, 2152 "actions": { 2153 "permit": [ 2154 null 2155 ] 2156 } 2157 } 2158 ] 2159 } 2160 }, 2161 { 2162 "acl-name": "mud-67390-v6to", 2163 "acl-type": "ipv6-acl", 2164 "aces": { 2165 "ace": [ 2166 { 2167 "rule-name": "ent0-todev", 2168 "matches": { 2169 "ietf-mud:mud-acl"{ 2170 "controller": "urn:ietf:params:mud:dns" 2171 }, 2172 "protocol": 17, 2173 "source-port-range": { 2174 "lower-port": 53, 2175 "upper-port": 53 2176 } 2177 }, 2178 "actions": { 2179 "permit": [ 2180 null 2181 ] 2182 } 2183 }, 2184 { 2185 "rule-name": "ent1-todev", 2186 "matches": { 2187 "ietf-mud:mud-acl"{ 2188 "controller": "urn:ietf:params:mud:ntp" 2189 }, 2190 "protocol": 17 2191 }, 2192 "actions": { 2193 "permit": [ 2194 null 2195 ] 2196 } 2197 } 2198 ] 2199 } 2200 }, 2201 { 2202 "acl-name": "mud-67390-v6fr", 2203 "acl-type": "ipv6-acl", 2204 "aces": { 2205 "ace": [ 2206 { 2207 "rule-name": "ent0-frdev", 2208 "matches": { 2209 "ietf-mud:mud-acl"{ 2210 "controller": "urn:ietf:params:mud:dns" 2211 }, 2212 "protocol": 17, 2213 "destination-port-range": { 2214 "lower-port": 53, 2215 "upper-port": 53 2216 } 2217 }, 2218 "actions": { 2219 "permit": [ 2220 null 2221 ] 2222 } 2223 }, 2224 { 2225 "rule-name": "ent1-frdev", 2226 "matches": { 2227 "ietf-mud:mud-acl"{ 2228 "controller": "urn:ietf:params:mud:ntp" 2229 }, 2230 "protocol": 17 2231 }, 2232 "actions": { 2233 "permit": [ 2234 null 2235 ] 2236 } 2237 } 2238 ] 2239 } 2240 } 2241 ] 2242 } 2244 Appendix C. A Sample Extension: DETNET-indicator 2246 In this sample extension we augment the core MUD model to indicate 2247 whether the device implements DETNET. If a device later attempts to 2248 make use of DETNET, an notification or exception might be generated. 2249 Note that this example is intended only for illustrative purposes. 2251 Extension Name: "Example-Extension" (to be used in the extensions list) 2252 Standard: this document (but do not register the example) 2254 This extension augments the MUD model to include a single node, using 2255 the following sample module that has the following tree structure: 2257 module: ietf-mud-detext-example 2258 augment /ietf-mud:mud: 2259 +--rw is-detnet-required? boolean 2261 The model is defined as follows: 2263 file "ietf-mud-detext-example@2016-09-07.yang" 2264 module ietf-mud-detext-example { 2265 yang-version 1.1; 2266 namespace "urn:ietf:params:xml:ns:yang:ietf-mud-detext-example"; 2267 prefix ietf-mud-detext-example; 2269 import ietf-mud { 2270 prefix ietf-mud; 2271 } 2273 organization 2274 "IETF OPSAWG (Ops Area) Working Group"; 2275 contact 2276 "WG Web: http://tools.ietf.org/wg/opsawg/ 2277 WG List: opsawg@ietf.org 2278 Author: Eliot Lear 2279 lear@cisco.com 2280 Author: Ralph Droms 2281 rdroms@gmail.com 2282 Author: Dan Romascanu 2283 dromasca@gmail.com 2285 "; 2286 description 2287 "Sample extension to a MUD module to indicate a need 2288 for DETNET support."; 2290 revision 2017-09-05 { 2291 description 2292 "Initial revision."; 2293 reference 2294 "RFC XXXX: Manufacturer Usage Description 2295 Specification"; 2296 } 2298 augment "/ietf-mud:mud" { 2299 description 2300 "This adds a simple extension for a manufacturer 2301 to indicate whether DETNET is required by a 2302 device."; 2303 leaf is-detnet-required { 2304 type boolean; 2305 description 2306 "This value will equal true if a device requires 2307 detnet to properly function"; 2308 } 2309 } 2310 } 2311 2312 Using the previous example, we now show how the extension would be 2313 expressed: 2315 { 2316 "ietf-mud:mud": { 2317 "mud-url": "https://bms.example.com/.well-known/mud/v1/lightbulb2", 2318 "last-update": "2017-08-30T15:48:42+02:00", 2319 "systeminfo": "https://bms.example.com/descriptions/lightbulb2", 2320 "cache-validity": 48, 2321 "extensions": [ 2322 "ietf-mud-detext-example" 2323 ], 2324 "ietf-mud-detext-example:is-detnet-required": "false", 2325 "from-device-policy": { 2326 "access-lists": { 2327 "access-list": [ 2328 { 2329 "acl-name": "mud-16595-v6fr", 2330 "acl-type": "ietf-access-control-list:ipv6-acl" 2331 } 2332 ] 2333 } 2334 }, 2335 "to-device-policy": { 2336 "access-lists": { 2337 "access-list": [ 2338 { 2339 "acl-name": "mud-16595-v4to", 2340 "acl-type": "ietf-access-control-list:ipv6-acl" 2341 } 2342 ] 2343 } 2344 } 2345 }, 2346 "ietf-access-control-list:access-lists": { 2347 "acl": [ 2348 { 2349 "acl-name": "mud-16595-v6to", 2350 "acl-type": "ipv6-acl", 2351 "access-list-entries": { 2352 "ace": [ 2353 { 2354 "rule-name": "cl0-todev", 2355 "matches": { 2356 "ipv4-acl": { 2357 "ietf-acldns:src-dnsname": "service.bms.example.com" 2358 }, 2359 "protocol": 6, 2360 "source-port-range": { 2361 "lower-port": 443, 2362 "upper-port": 443 2363 }, 2364 "tcp-acl": { 2365 "ietf-mud:direction-initiated": "to-device" 2366 } 2367 }, 2368 "actions": { 2369 "permit": [ 2370 null 2371 ] 2372 } 2373 } 2374 ] 2375 } 2376 }, 2377 { 2378 "acl-name": "mud-16595-v6fr", 2379 "acl-type": "ipv6-acl", 2380 "aces": { 2381 "ace": [ 2382 { 2383 "rule-name": "cl0-frdev", 2384 "matches": { 2385 "ipv6-acl": { 2386 "ietf-acldns:dst-dnsname": "service.bms.example.com" 2387 }, 2388 "protocol": 6, 2389 "destination-port-range": { 2390 "lower-port": 443, 2391 "upper-port": 443 2392 }, 2393 "tcp-acl": { 2394 "ietf-mud:direction-initiated": "to-device" 2395 } 2396 }, 2397 "actions": { 2398 "permit": [ 2399 null 2400 ] 2401 } 2402 } 2403 ] 2404 } 2405 } 2406 ] 2407 } 2409 } 2411 Authors' Addresses 2413 Eliot Lear 2414 Cisco Systems 2415 Richtistrasse 7 2416 Wallisellen CH-8304 2417 Switzerland 2419 Phone: +41 44 878 9200 2420 Email: lear@cisco.com 2422 Ralph Droms 2424 Phone: +1 978 376 3731 2425 Email: rdroms@gmail.com 2427 Dan Romascanu 2429 Phone: +972 54 5555347 2430 Email: dromasca@gmail.com