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'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reference: RFC 2818 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) == Outdated reference: A later version (-20) exists of draft-ietf-netmod-rfc6087bis-14 -- Obsolete informational reference (is this intentional?): RFC 7042 (Obsoleted by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 15, 2018 6 D. Romascanu 7 September 11, 2017 9 Manufacturer Usage Description Specification 10 draft-ietf-opsawg-mud-09 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 15, 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 . . . . . . . . . . . . . . . . . . . . . . . 52 121 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. MUD controllers MAY ignore any particular component 484 of a description or MAY ignore the description in its entirety, and 485 SHOULD carefully inspect all MUD descriptions. Publishers of MUD 486 files MUST NOT include other nodes except as described in 487 Section 3.7. See that section for more information. 489 ======= This module is structured into three parts: 491 o The first container "mud" holds information that is relevant to 492 retrieval and validity of the MUD file itself, as well as policy 493 intended to and from the Thing. 495 o The second component augments the matching container of the ACL 496 model to add several nodes that are relevant to the MUD URL, or 497 otherwise abstracted for use within a local environment. 499 o The third component augments the tcp-acl container of the ACL 500 model to add the ability to match on the direction of initiation 501 of a TCP connection. 503 A valid MUD file will contain two root objects, a "mud" container and 504 an "access-lists" container. Extensions may add additional root 505 objects as required. 507 A simplified graphical representation of the data models is used in 508 this document. The meaning of the symbols in these diagrams is 509 explained in [I-D.ietf-netmod-rfc6087bis]. 511 module: ietf-mud 512 +--rw mud! 513 +--rw mud-url inet:uri 514 +--rw last-update yang:date-and-time 515 +--rw cache-validity? uint8 516 +--rw masa-server? inet:uri 517 +--rw is-supported boolean 518 +--rw systeminfo? inet:uri 519 +--rw extensions* string 520 +--rw from-device-policy 521 | +--rw access-lists 522 | +--rw access-list* [acl-name acl-type] 523 | +--rw acl-name -> /acl:access-lists/acl/acl-name 524 | +--rw acl-type identityref 525 +--rw to-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 augment /acl:access-lists/acl:acl/acl:aces/ 531 acl:ace/acl:matches: 532 +--rw mud-acl 533 +--rw manufacturer? inet:host 534 +--rw same-manufacturer? empty 535 +--rw model? inet:uri 536 +--rw local-networks? empty 537 +--rw controller? inet:uri 538 +--rw my-controller? empty 539 augment /acl:access-lists/acl:acl/acl:aces/ 540 acl:ace/acl:matches/acl:tcp-acl: 541 +--rw direction-initiated? direction 543 3. Data Node Definitions 545 Note that in this section, when we use the term "match" we are 546 referring to the ACL model "matches" node, and thus returns positive 547 such that an action should be applied. 549 The following nodes are defined. 551 3.1. to-device-policy and from-device-policy containers 553 [I-D.ietf-netmod-acl-model] describes access-lists but does not 554 attempt to indicate where they are applied as that is handled 555 elsewhere in a configuration. However, in this case, a MUD file must 556 be explicit in describing the communication pattern of a Thing, and 557 that includes indicating what is to be permitted or denied in either 558 direction of communication. Hence each of these containers indicate 559 the appropriate direction of a flow in association with a particular 560 Thing. They contain references to specific access-lists. 562 3.2. last-update 564 This is a date-and-time value of when the MUD file was generated. 565 This is akin to a version number. Its form is taken from [RFC6991] 566 which, for those keeping score, in turn was taken from Section 5.6 of 567 [RFC3339], which was taken from [ISO.8601.1988]. 569 3.3. cache-validity 571 This uint8 is the period of time in hours that a network management 572 station MUST wait since its last retrieval before checking for an 573 update. It is RECOMMENDED that this value be no less than 24 and 574 MUST NOT be more than 168 for any Thing that is supported. This 575 period SHOULD be no shorter than any period determined through HTTP 576 caching directives (e.g., "cache-control" or "Expires"). N.B., 577 expiring of this timer does not require the MUD controller to discard 578 the MUD file, nor terminate access to a Thing. See Section 15 for 579 more information. 581 3.4. masa-server 583 This optional node refers to the URL that should be used to resolve 584 the MASA service, as specified in 585 [I-D.ietf-anima-bootstrapping-keyinfra]. 587 3.5. is-supported 589 This boolean is an indication from the manufacturer to the network 590 administrator as to whether or not the Thing is supported. In this 591 context a Thing is said to be supported if the manufacturer might 592 issue an update to the Thing or if the manufacturer might update the 593 MUD file. 595 3.6. systeminfo 597 This is a URL that points to a description of the Thing to be 598 connected. The intent is for administrators to be able to read about 599 what the Thing is the first time the MUD-URL is used. 601 3.7. extensions 603 This optional leaf-list names MUD extensions that are used in the MUD 604 file. Note that NO MUD extensions may be used in a MUD file prior to 605 the extensions being declared. Implementations MUST ignore any node 606 in this file that they do not understand. 608 Note that extensions can either extend the MUD file as described in 609 the previous paragraph, or they might reference other work. A good 610 example of how this might be done is the masa-server URI that is 611 defined in the base model. We say nothing about the semantics of 612 that work here, but rather leave that to the underlying specification 613 found in [I-D.ietf-anima-bootstrapping-keyinfra]. 615 3.8. manufacturer 617 This node consists of a hostname that would be matched against the 618 authority component of another Thing's MUD URL. In its simplest form 619 "manufacturer" and "same-manufacturer" may be implemented as access- 620 lists. In more complex forms, additional network capabilities may be 621 used. For example, if one saw the line "manufacturer" : 622 "flobbidy.example.com", then all Things that registered with a MUD 623 URL that contained flobbity.example.com in its authority section 624 would match. 626 3.9. same-manufacturer 628 This is an equivalent for when the manufacturer element is used to 629 indicate the authority that is found in another Thing's MUD URL 630 matches that of the authority found in this Thing's MUD URL. For 631 example, if the Thing's MUD URL were https://b1.example.com/.well- 632 known/mud/v1/ThingV1, then all devices that had MUD URL with an 633 authority section of b1.example.com would match. 635 3.10. model 637 This string matches the entire MUD URL, thus covering the model that 638 is unique within the context of the authority. It may contain not 639 only model information, but versioning information as well, and any 640 other information that the manufacturer wishes to add. The intended 641 use is for devices of this precise class to match, to permit or deny 642 communication between one another. 644 3.11. local-networks 646 This null-valued node expands to include local networks. Its default 647 expansion is that packets must not traverse toward a default route 648 that is received from the router. However, administrators may expand 649 the expression as is appropriate in their deployments. 651 3.12. controller 653 This URI specifies a value that a controller will register with the 654 mud controller. The node then is expanded to the set of hosts that 655 are so registered. This node may also be a URN. In this case, the 656 URN describes a well known service, such as DNS or NTP. 658 Great care should be used when invoking the controller class. For 659 one thing, it requires some understanding by the administrator as to 660 when it is appropriate. Classes that are standardized may make it 661 possible to easily name devices that support standard functions. For 662 instance, the MUD controller could have some knowledge of which DNS 663 servers should be used for any particular group of Things. Non- 664 standard classes will likely require some sort of administrator 665 interaction. Pre-registration in such classes by controllers with 666 the MUD server is encouraged. The mechanism to do that is beyond the 667 scope of this work. 669 Controller URIs MAY take the form of a URL (e.g. "http[s]://"). 670 However, MUD controllers MUST NOT resolve and retrieve such files, 671 and it is RECOMMENDED that there be no such file at this time, as 672 their form and function may be defined at a point in the future. For 673 now, URLs should serve simply as class names and be populated by the 674 local deployment administrator. 676 3.13. my-controller 678 This null-valued node signals to the MUD controller to use whatever 679 mapping it has for this MUD-URL to a particular group of hosts. This 680 may require prompting the administrator for class members. Future 681 work should seek to automate membership management. 683 3.14. direction-initiated 685 When applied this matches packets when the flow was initiated in the 686 corresponding direction. [RFC6092] specifies IPv6 guidance best 687 practices. While that document is scoped specifically to IPv6, its 688 contents are applicable for IPv4 as well. When this flag is set, and 689 the system has no reason to believe a flow has been initiated it MUST 690 drop the packet. This node may be implemented in its simplest form 691 by looking at naked SYN bits, but may also be implemented through 692 more stateful mechanisms. 694 4. Processing of the MUD file 696 To keep things relatively simple in addition to whatever definitions 697 exist, we also apply two additional default behaviors: 699 o Anything not explicitly permitted is denied. 701 o Local DNS and NTP are, by default, permitted to and from the 702 Thing. 704 An explicit description of the defaults can be found in Appendix B. 706 5. What does a MUD URL look like? 708 To begin with, MUD takes full advantage of both the https: scheme and 709 the use of .well-known. HTTPS is important in this case because a 710 man in the middle attack could otherwise harm the operation of a 711 class of Things. .well-known is used because we wish to add 712 additional structure to the URL, and want to leave open for future 713 versions both the means by which the URL is processed and the format 714 of the MUD file retrieved (there have already been some discussions 715 along these lines). The URL appears as follows: 717 mud-url = "https://" authority "/.well-known/mud/" mud-rev 718 "/" modelinfo ( "?" extras ) 719 ; authority is from RFC3986 720 mud-rev = "v1" 721 modelinfo = segment ; from RFC3986 722 extras = query ; from RFC3986 724 mud-rev signifies the version of the manufacturer usage description 725 file. This memo specifies "v1" of that file. Later versions may 726 permit additional schemas or modify the format. In order to provide 727 for the broadest compatibility for the various transmission 728 mechanisms, the length of the URL for v1 MUST NOT exceed 255 octets. 730 Taken together with the mud-url, "modelinfo" represents a Thing model 731 as the manufacturer wishes to represent it. It could be a brand name 732 or something more specific. It also may provide a means to indicate 733 what version the product is. Specifically if it has been updated in 734 the field, this is the place where evidence of that update would 735 appear. The field should be changed when the intended communication 736 patterns of a Thing change. While from a controller standpoint, only 737 comparison and matching operations are safe, it is envisioned that 738 updates will require some administrative review. Processing of this 739 URL occurs as specified in [RFC2818] and [RFC3986]. 741 "extras" is intended for use by the MUD controller to provide 742 additional information such as posture about the Thing to the MUD 743 file server. This field MUST NOT be configured on the Thing itself 744 by a manufacturer - that is what "modelinfo" is for. It is left as 745 future work to define the full semantics of this field. 747 6. The MUD YANG Model 749 file "ietf-mud@2017-09-07.yang" 750 module ietf-mud { 751 yang-version 1.1; 752 namespace "urn:ietf:params:xml:ns:yang:ietf-mud"; 753 prefix ietf-mud; 755 import ietf-access-control-list { 756 prefix acl; 757 } 758 import ietf-yang-types { 759 prefix yang; 760 } 761 import ietf-inet-types { 762 prefix inet; 763 } 765 organization 766 "IETF OPSAWG (Ops Area) Working Group"; 767 contact 768 "WG Web: http://tools.ietf.org/wg/opsawg/ 769 WG List: opsawg@ietf.org 770 Author: Eliot Lear 771 lear@cisco.com 772 Author: Ralph Droms 773 rdroms@gmail.com 774 Author: Dan Romascanu 775 dromasca@gmail.com 777 "; 778 description 779 "This YANG module defines a component that augments the 780 IETF description of an access list. This specific module 781 focuses on additional filters that include local, model, 782 and same-manufacturer. 784 This module is intended to be serialized via JSON and stored 785 as a file, as described in RFC XXXX [RFC Editor to fill in with 786 this document #]. 788 Copyright (c) 2016,2017 IETF Trust and the persons 789 identified as the document authors. All rights reserved. 790 Redistribution and use in source and binary forms, with or 791 without modification, is permitted pursuant to, and subject 792 to the license terms contained in, the Simplified BSD 793 License set forth in Section 4.c of the IETF Trust's Legal 794 Provisions Relating to IETF Documents 795 (http://trustee.ietf.org/license-info). 796 This version of this YANG module is part of RFC XXXX; see 797 the RFC itself for full legal notices."; 799 revision 2017-09-05 { 800 description 801 "Initial proposed standard."; 802 reference 803 "RFC XXXX: Manufacturer Usage Description 804 Specification"; 805 } 807 typedef direction { 808 type enumeration { 809 enum "to-device" { 810 description 811 "packets or flows destined to the target 812 Thing"; 813 } 814 enum "from-device" { 815 description 816 "packets or flows destined from 817 the target Thing"; 818 } 819 } 820 description 821 "Which way are we talking about?"; 822 } 824 container mud { 825 presence "Enabled for this particular MUD-URL"; 826 description 827 "MUD related information, as specified 828 by RFC-XXXX [RFC Editor to fill in]."; 829 uses mud-grouping; 830 } 832 grouping mud-grouping { 833 description 834 "Information about when support end(ed), and 835 when to refresh"; 836 leaf mud-url { 837 type inet:uri; 838 mandatory true; 839 description 840 "This is the MUD-URL associated with the entry found 841 in a MUD file."; 842 } 843 leaf last-update { 844 type yang:date-and-time; 845 mandatory true; 846 description 847 "This is intended to be when the current MUD file 848 was generated. MUD Controllers SHOULD NOT check 849 for updates between this time plus cache validity"; 850 } 851 leaf cache-validity { 852 type uint8 { 853 range "1..168"; 854 } 855 units "hours"; 856 default "48"; 857 description 858 "The information retrieved from the MUD server is 859 valid for these many hours, after which it should 860 be refreshed. N.B. MUD controller implementations 861 need not discard MUD files beyond this period."; 862 } 863 leaf masa-server { 864 type inet:uri; 865 description 866 "The URI of the MASA server that network 867 elements should forward requests to for this Thing."; 868 } 869 leaf is-supported { 870 type boolean; 871 mandatory true; 872 description 873 "This boolean indicates whether or not the Thing is 874 currently supported by the manufacturer."; 875 } 876 leaf systeminfo { 877 type inet:uri; 878 description 879 "A URL to a description of this Thing. This 880 should be a brief localized description. The 881 reference text should be no more than octets. 882 systeminfo may be displayed to the user to 883 determine whether to allow the Thing on the 884 network."; 885 } 886 leaf-list extensions { 887 type string { 888 length "1..40"; 889 } 890 description 891 "A list of extension names that are used in this MUD 892 file. Each name is registered with the IANA and 893 described in an RFC."; 894 } 895 container from-device-policy { 896 description 897 "The policies that should be enforced on traffic 898 coming from the device. These policies are not 899 necessarily intended to be enforced at a single 900 point, but may be rendered by the controller to any 901 relevant enorcement points in the network or 902 elsewhere."; 903 uses access-lists; 904 } 905 container to-device-policy { 906 description 907 "The policies that should be enforced on traffic 908 going to the device. These policies are not 909 necessarily intended to be enforced at a single 910 point, but may be rendered by the controller to any 911 relevant enorcement points in the network or 912 elsewhere."; 913 uses access-lists; 914 } 915 } 917 grouping access-lists { 918 description 919 "A grouping for access lists in the context of device 920 policy."; 921 container access-lists { 922 description 923 "The access lists that should be applied to traffic 924 to or from the device."; 925 list access-list { 926 key "acl-name acl-type"; 927 description 928 "Each entry on this list refers to an ACL that 929 should be present in the overall access list 930 data model. Each ACL is identified by name and 931 type."; 932 leaf acl-name { 933 type leafref { 934 path "/acl:access-lists/acl:acl/acl:acl-name"; 935 } 936 description 937 "The name of the ACL for this entry."; 938 } 939 leaf acl-type { 940 type identityref { 941 base acl:acl-base; 942 } 943 description 944 "The type of the ACL for this entry. The name is 945 scoped ONLY to the MUD file, and may not be unique 946 in any other circumstance."; 947 } 948 } 949 } 950 } 952 augment "/acl:access-lists/acl:acl/acl:aces/acl:ace/acl:matches" { 953 description 954 "adding abstractions to avoid need of IP addresses"; 955 container mud-acl { 956 description 957 "MUD-specific matches."; 958 leaf manufacturer { 959 type inet:host; 960 description 961 "A domain that is intended to match the authority 962 section of the MUD-URL. This node is used to specify 963 one or more manufacturers a device should 964 be authorized to access."; 965 } 966 leaf same-manufacturer { 967 type empty; 968 description 969 "This node matches the authority section of the MUD-URL 970 of a Thing. It is intended to grant access to all 971 devices with the same authority section."; 972 } 973 leaf model { 974 type inet:uri; 975 description 976 "Devices of the specified model type will match if 977 they have an identical MUD-URL."; 978 } 979 leaf local-networks { 980 type empty; 981 description 982 "IP addresses will match this node if they are 983 considered local addresses. A local address may be 984 a list of locally defined prefixes and masks 985 that indicate a particular administrative scope."; 986 } 987 leaf controller { 988 type inet:uri; 989 description 990 "This node names a class that has associated with it 991 zero or more IP addresses to match against. These 992 may be scoped to a manufacturer or via a standard 993 URN."; 994 } 995 leaf my-controller { 996 type empty; 997 description 998 "This node matches one or more network elements that 999 have been configured to be the controller for this 1000 Thing, based on its MUD-URL."; 1001 } 1002 } 1003 } 1004 augment "/acl:access-lists/acl:acl/acl:aces/" + 1005 "acl:ace/acl:matches/acl:tcp-acl" { 1006 description 1007 "Adding domain names to matching"; 1008 leaf direction-initiated { 1009 type direction; 1010 description 1011 "This node matches based on which direction a 1012 connection was initiated. The means by which that 1013 is determined is discussed in this document."; 1014 } 1015 } 1016 } 1018 1020 7. The Domain Name Extension to the ACL Model 1022 This module specifies an extension to IETF-ACL model such that domain 1023 names may be referenced by augmenting the "matches" node. Different 1024 implementations may deploy differing methods to maintain the mapping 1025 between IP address and domain name, if indeed any are needed. 1026 However, the intent is that resources that are referred to using a 1027 name should be authorized (or not) within an access list. 1029 The structure of the change is as follows: 1031 module: ietf-acldns 1032 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/ 1033 acl:matches/acl:ipv4-acl: 1034 +--rw src-dnsname? inet:host 1035 +--rw dst-dnsname? inet:host 1036 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/ 1037 acl:matches/acl:ipv6-acl: 1038 +--rw src-dnsname? inet:host 1039 +--rw dst-dnsname? inet:host 1041 The choice of these particular points in the access-list model is 1042 based on the assumption that we are in some way referring to IP- 1043 related resources, as that is what the DNS returns. A domain name in 1044 our context is defined in [RFC6991]. The augmentations are 1045 replicated across IPv4 and IPv6 to allow MUD file authors the ability 1046 to control the IP version that the Thing may utilize. 1048 The following node are defined. 1050 7.1. source-dnsname 1052 The argument corresponds to a domain name of a source as specified by 1053 inet:host. A number of means may be used to resolve hosts. What is 1054 important is that such resolutions be consistent with ACLs required 1055 by Things to properly operate. 1057 7.2. destination-dnsname 1059 The argument corresponds to a domain name of a destination as 1060 specified by inet:host See the previous section relating to 1061 resolution. 1063 7.3. The ietf-acldns Model 1065 file "ietf-acldns@2016-09-07.yang" 1066 module ietf-acldns { 1067 yang-version 1.1; 1068 namespace "urn:ietf:params:xml:ns:yang:ietf-acldns"; 1069 prefix "ietf-acldns"; 1071 import ietf-access-control-list { 1072 prefix "acl"; 1073 } 1075 import ietf-inet-types { 1076 prefix "inet"; 1077 } 1078 organization 1079 "IETF OPSAWG (Ops Area) Working Group"; 1081 contact 1082 "WG Web: http://tools.ietf.org/wg/opsawg/ 1083 WG List: opsawg@ietf.org 1084 Author: Eliot Lear 1085 lear@cisco.com 1086 Author: Ralph Droms 1087 rdroms@gmail.com 1088 Author: Dan Romascanu 1089 dromasca@gmail.com 1090 "; 1092 description 1093 "This YANG module defines a component that augments the 1094 IETF description of an access list to allow dns names 1095 as matching criteria."; 1097 revision "2016-07-20" { 1098 description "Base version of dnsname extension of ACL model"; 1099 reference "RFC XXXX: Manufacturer Usage Description 1100 Specification"; 1101 } 1103 grouping dns-matches { 1104 description "Domain names for matching."; 1106 leaf src-dnsname { 1107 type inet:host; 1108 description "domain name to be matched against"; 1109 } 1110 leaf dst-dnsname { 1111 type inet:host; 1112 description "domain name to be matched against"; 1113 } 1114 } 1116 augment "/acl:access-lists/acl:acl/acl:aces/acl:ace/" + 1117 "acl:matches/acl:ipv4-acl" { 1118 description "Adding domain names to matching"; 1119 uses dns-matches; 1120 } 1122 augment "/acl:access-lists/acl:acl/" + 1123 "acl:aces/acl:ace/" + 1124 "acl:matches/acl:ipv6-acl" { 1125 description "Adding domain names to matching"; 1126 uses dns-matches; 1127 } 1128 } 1129 1131 8. MUD File Example 1133 This example contains two access lists that are intended to provide 1134 outbound access to a cloud service on TCP port 443. 1136 { 1137 "ietf-mud:mud": { 1138 "mud-url": "https://bms.example.com/.well-known/mud/v1/lightbulb2000", 1139 "last-update": "2017-09-07T13:47:52+02:00", 1140 "systeminfo": "https://bms.example.com/descriptions/lightbulb2000", 1141 "cache-validity": 48, 1142 "from-device-policy": { 1143 "access-lists": { 1144 "access-list": [ 1145 { 1146 "acl-name": "mud-83312-v6fr", 1147 "acl-type": "ietf-access-control-list:ipv6-acl" 1148 } 1149 ] 1150 } 1151 }, 1152 "to-device-policy": { 1153 "access-lists": { 1154 "access-list": [ 1155 { 1156 "acl-name": "mud-83312-v6to", 1157 "acl-type": "ietf-access-control-list:ipv6-acl" 1158 } 1159 ] 1160 } 1161 } 1162 }, 1163 "ietf-access-control-list:access-lists": { 1164 "acl": [ 1165 { 1166 "acl-name": "mud-83312-v6to", 1167 "acl-type": "ipv6-acl", 1168 "access-list-entries": { 1169 "ace": [ 1170 { 1171 "rule-name": "cl0-todev", 1172 "matches": { 1173 "ipv6-acl": { 1174 "ietf-acldns:src-dnsname": "service.bms.example.com" 1175 }, 1176 "protocol": 6, 1177 "source-port-range": { 1178 "lower-port": 443, 1179 "upper-port": 443 1180 }, 1181 "tcp-acl": { 1182 "ietf-mud:direction-initiated": "from-device" 1183 } 1184 }, 1185 "actions": { 1186 "permit": [ 1187 null 1188 ] 1189 } 1190 } 1191 ] 1192 } 1193 }, 1194 { 1195 "acl-name": "mud-83312-v6fr", 1196 "acl-type": "ipv6-acl", 1197 "access-list-entries": { 1198 "ace": [ 1199 { 1200 "rule-name": "cl0-frdev", 1201 "matches": { 1202 "ipv6-acl": { 1203 "ietf-acldns:dst-dnsname": "service.bms.example.com" 1204 }, 1205 "protocol": 6, 1206 "destination-port-range": { 1207 "lower-port": 443, 1208 "upper-port": 443 1209 }, 1210 "tcp-acl": { 1211 "ietf-mud:direction-initiated": "from-device" 1212 } 1213 }, 1214 "actions": { 1215 "permit": [ 1216 null 1217 ] 1218 } 1219 } 1220 ] 1222 } 1223 } 1224 ] 1225 } 1226 } 1228 In this example, two policies are declared, one from the Thing and 1229 the other to the Thing. Each policy names an access list that 1230 applies to the Thing, and one that applies from. Within each access 1231 list, access is permitted to packets flowing to or from the Thing 1232 that can be mapped to the domain name of "service.bms.example.com". 1233 For each access list, the enforcement point should expect that the 1234 thing initiated the connection. 1236 9. The MUD URL DHCP Option 1238 The IPv4 MUD URL client option has the following format: 1240 +------+-----+------------------------------ 1241 | code | len | MUD URL 1242 +------+-----+------------------------------ 1244 Code OPTION_MUD_URL_V4 (161) is assigned by IANA. len is a single 1245 octet that indicates the length of the URL in octets. MUD URL is a 1246 URL. MUD URLs MUST NOT exceed 255 octets. 1248 The IPv6 MUD URL client option has the following format: 1250 0 1 2 3 1251 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 1252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1253 | OPTION_MUD_URL_V6 | option-length | 1254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1255 | MUD URL | 1256 | ... | 1257 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1259 OPTION_MUD_URL_V6 (112; assigned by IANA). 1261 option-length contains the length of the URL in octets. 1263 The intent of this option is to provide both a new Thing classifier 1264 to the network as well as some recommended configuration to the 1265 routers that implement policy. However, it is entirely the purview 1266 of the network system as managed by the network administrator to 1267 decide what to do with this information. The key function of this 1268 option is simply to identify the type of Thing to the network in a 1269 structured way such that the policy can be easily found with existing 1270 toolsets. 1272 9.1. Client Behavior 1274 A DHCPv4 client MAY emit a DHCPv4 option and a DHCPv6 client MAY emit 1275 DHCPv6 option. These options are singletons, as specified in 1276 [RFC7227]. Because clients are intended to have at most one MUD URL 1277 associated with them, they may emit at most one MUD URL option via 1278 DHCPv4 and one MUD URL option via DHCPv6. In the case where both v4 1279 and v6 DHCP options are emitted, the same URL MUST be used. 1281 Clients SHOULD log or otherwise report improper acknowledgments from 1282 servers, but they MUST NOT modify their MUD URL configuration based 1283 on a server's response. The server's response is only an 1284 acknowledgment that the server has processed the option, and promises 1285 no specific network behavior to the client. In particular, it may 1286 not be possible for the server to retrieve the file associated with 1287 the MUD URL, or the local network administration may not wish to use 1288 the usage description. Neither of these situations should be 1289 considered in any way exceptional. 1291 9.2. Server Behavior 1293 A DHCP server may ignore these options or take action based on 1294 receipt of these options. If a server successfully parses the option 1295 and the URL, it MUST return the option with length field set to zero 1296 and a corresponding null URL field as an acknowledgment. Even in 1297 this circumstance, no specific network behavior is guaranteed. When 1298 a server consumes this option, it will either forward the URL and 1299 relevant client information (such as the gateway address or giaddr) 1300 to a network management system, or it will retrieve the usage 1301 description itself by resolving the URL. 1303 DHCP servers may implement MUD functionality themselves or they may 1304 pass along appropriate information to a network management system or 1305 MUD controller. A DHCP server that does process the MUD URL MUST 1306 adhere to the process specified in [RFC2818] and [RFC5280] to 1307 validate the TLS certificate of the web server hosting the MUD file. 1308 Those servers will retrieve the file, process it, create and install 1309 the necessary configuration on the relevant network element. Servers 1310 SHOULD monitor the gateway for state changes on a given interface. A 1311 DHCP server that does not provide MUD functionality and has forwarded 1312 a MUD URL to a MUD controller MUST notify the MUD controller of any 1313 corresponding change to the DHCP state of the client (such as 1314 expiration or explicit release of a network address lease). 1316 9.3. Relay Requirements 1318 There are no additional requirements for relays. 1320 10. The Manufacturer Usage Description (MUD) URL X.509 Extension 1322 This section defines an X.509 non-critical certificate extension that 1323 contains a single Uniform Resource Locator (URL) that points to an 1324 on-line Manufacturer Usage Description concerning the certificate 1325 subject. URI must be represented as described in Section 7.4 of 1326 [RFC5280]. 1328 Any Internationalized Resource Identifiers (IRIs) MUST be mapped to 1329 URIs as specified in Section 3.1 of [RFC3987] before they are placed 1330 in the certificate extension. 1332 The semantics of the URL are defined Section 5 of this document. 1334 The choice of id-pe is based on guidance found in Section 4.2.2 of 1335 [RFC5280]: 1337 These extensions may be used to direct applications to on-line 1338 information about the issuer or the subject. 1340 The MUD URL is precisely that: online information about the 1341 particular subject. 1343 The new extension is identified as follows: 1345 1347 MUDURLExtnModule-2016 { iso(1) identified-organization(3) dod(6) 1348 internet(1) security(5) mechanisms(5) pkix(7) 1349 id-mod(0) id-mod-mudURLExtn2016(88) } 1351 DEFINITIONS IMPLICIT TAGS ::= BEGIN 1353 -- EXPORTS ALL -- 1355 IMPORTS 1356 EXTENSION 1357 FROM PKIX-CommonTypes-2009 1358 { iso(1) identified-organization(3) dod(6) internet(1) 1359 security(5) mechanisms(5) pkix(7) id-mod(0) 1360 id-mod-pkixCommon-02(57) } 1362 id-pe 1363 FROM PKIX1Explicit-2009 1364 { iso(1) identified-organization(3) dod(6) internet(1) 1365 security(5) mechanisms(5) pkix(7) id-mod(0) 1366 id-mod-pkix1-explicit-02(51) } ; 1367 MUDCertExtensions EXTENSION ::= { ext-MUDURL, ... } 1368 ext-MUDURL EXTENSION ::= { SYNTAX MUDURLSyntax 1369 IDENTIFIED BY id-pe-mud-url } 1371 id-pe-mud-url OBJECT IDENTIFIER ::= { id-pe 25 } 1373 MUDURLSyntax ::= IA5String 1375 END 1377 1379 While this extension can appear in either an 802.AR manufacturer 1380 certificate (IDevID) or deployment certificate (LDevID), of course it 1381 is not guaranteed in either, nor is it guaranteed to be carried over. 1382 It is RECOMMENDED that MUD controller implementations maintain a 1383 table that maps a Thing to its MUD-URL based on IDevIDs. 1385 11. The Manufacturer Usage Description LLDP extension 1387 The IEEE802.1AB Link Layer Discovery Protocol (LLDP) is a one hop 1388 vendor-neutral link layer protocol used by end hosts network Things 1389 for advertising their identity, capabilities, and neighbors on an 1390 IEEE 802 local area network. Its Type-Length-Value (TLV) design 1391 allows for 'vendor-specific' extensions to be defined. IANA has a 1392 registered IEEE 802 organizationally unique identifier (OUI) defined 1393 as documented in [RFC7042]. The MUD LLDP extension uses a subtype 1394 defined in this document to carry the MUD URL. 1396 The LLDP vendor specific frame has the following format: 1398 +--------+--------+----------+---------+-------------- 1399 |TLV Type| len | OUI |subtype | MUD URL 1400 | =127 | |= 00 00 5E| = 1 | 1401 |(7 bits)|(9 bits)|(3 octets)|(1 octet)|(1-255 octets) 1402 +--------+--------+----------+---------+-------------- 1404 where: 1406 o TLV Type = 127 indicates a vendor-specific TLV 1408 o len - indicates the TLV string length 1410 o OUI = 00 00 5E is the organizationally unique identifier of IANA 1412 o subtype = 1 (to be assigned by IANA for the MUD URL) 1414 o MUD URL - the length MUST NOT exceed 255 octets 1416 The intent of this extension is to provide both a new Thing 1417 classifier to the network as well as some recommended configuration 1418 to the routers that implement policy. However, it is entirely the 1419 purview of the network system as managed by the network administrator 1420 to decide what to do with this information. The key function of this 1421 extension is simply to identify the type of Thing to the network in a 1422 structured way such that the policy can be easily found with existing 1423 toolsets. 1425 Hosts, routers, or other network Things that implement this option 1426 are intended to have at most one MUD URL associated with them, so 1427 they may transmit at most one MUD URL value. 1429 Hosts, routers, or other network Things that implement this option 1430 may ignore these options or take action based on receipt of these 1431 options. For example they may fill in information in the respective 1432 extensions of the LLDP Management Information Base (LLDP MIB). LLDP 1433 operates in a one-way direction. LLDPDUs are not exchanged as 1434 information requests by one Thing and response sent by another Thing. 1435 The other Things do not acknowledge LLDP information received from a 1436 Thing. No specific network behavior is guaranteed. When a Thing 1437 consumes this extension, it may either forward the URL and relevant 1438 remote Thing information to a MUD controller, or it will retrieve the 1439 usage description by resolving the URL in accordance with normal HTTP 1440 semantics. 1442 12. Creating and Processing of Signed MUD Files 1444 Because MUD files contain information that may be used to configure 1445 network access lists, they are sensitive. To insure that they have 1446 not been tampered with, it is important that they be signed. We make 1447 use of DER-encoded Cryptographic Message Syntax (CMS) [RFC5652] for 1448 this purpose. 1450 12.1. Creating a MUD file signature 1452 A MUD file MUST be signed using CMS as an opaque binary object. In 1453 order to make successful verification more likely, intermediate 1454 certificates SHOULD be included. The signature is stored at the same 1455 location as the MUD URL but with the suffix of ".p7s". Signatures 1456 are transferred using content-type "application/pkcs7-signature". 1458 For example: 1460 % openssl cms -sign -signer mancertfile -inkey mankey \ 1461 -in mudfile -binary -outform DER - \ 1462 -certfile intermediatecert -out mudfile.p7s 1464 Note: A MUD file may need to be re-signed if the signature expires. 1466 12.2. Verifying a MUD file signature 1468 Prior to retrieving a MUD file the MUD controller SHOULD retrieve the 1469 MUD signature file using the MUD URL with a suffix of ".p7s". For 1470 example, if the MUD URL is "https://example.com/.well-known/v1/ 1471 modela", the MUD signature URL will be "https://example.com/.well- 1472 known/v1/modela.p7s". 1474 Upon retrieving a MUD file, a MUD controller MUST validate the 1475 signature of the file before continuing with further processing. A 1476 MUD controller MUST cease processing of that file it cannot validate 1477 the chain of trust to a known trust anchor until an administrator has 1478 given approval. 1480 The purpose of the signature on the file is to assign accountability 1481 to an entity, whose reputation can be used to guide administrators on 1482 whether or not to accept a given MUD file. It is already common 1483 place to check web reputation on the location of a server on which a 1484 file resides. While it is likely that the manufacturer will be the 1485 signer of the file, this is not strictly necessary, and may not be 1486 desirable. For one thing, in some environments, integrators may 1487 install their own certificates. For another, what is more important 1488 is the accountability of the recommendation, and not the 1489 cryptographic relationship between the device and the file. 1491 An example: 1493 % openssl cms -verify -in mudfile.p7s -inform DER -content mudfile 1495 Note the additional step of verifying the common trust root. 1497 13. Extensibility 1499 One of our design goals is to see that MUD files are able to be 1500 understood by as broad a cross-section of systems as is possible. 1501 Coupled with the fact that we have also chosen to leverage existing 1502 mechanisms, we are left with no ability to negotiate extensions and a 1503 limited desire for those extensions in any event. A such, a two-tier 1504 extensibility framework is employed, as follows: 1506 1. At a coarse grain, a protocol version is included in a MUD URL. 1507 This memo specifies MUD version 1. Any and all changes are 1508 entertained when this version is bumped. Transition approaches 1509 between versions would be a matter for discussion in future 1510 versions. 1512 2. At a finer grain, only extensions that would not incur additional 1513 risk to the Thing are permitted. Specifically, adding nodes to 1514 the mud container is permitted with the understanding that such 1515 additions will be ignored by unaware implementations. Any such 1516 extensions SHALL be standardized through the IETF process, and 1517 MUST be named in the "extensions" list. MUD controllers MUST 1518 ignore YANG nodes they do not understand and SHOULD create an 1519 exception to be resolved by an administrator, so as to avoid any 1520 policy inconsistencies. 1522 14. Deployment Considerations 1524 Because MUD consists of a number of architectural building blocks, it 1525 is possible to assemble different deployment scenarios. One key 1526 aspect is where to place policy enforcement. In order to protect the 1527 Thing from other Things within a local deployment, policy can be 1528 enforced on the nearest switch or access point. In order to limit 1529 unwanted traffic within a network, it may also be advisable to 1530 enforce policy as close to the Internet as possible. In some 1531 circumstances, policy enforcement may not be available at the closest 1532 hop. At that point, the risk of so-called east-west infection is 1533 increased to the number of Things that are able to communicate 1534 without protection. 1536 A caution about some of the classes: admission of a Thing into the 1537 "manufacturer" and "same-manufacturer" class may have impact on 1538 access of other Things. Put another way, the admission may grow the 1539 access-list on switches connected to other Things, depending on how 1540 access is managed. Some care should be given on managing that 1541 access-list growth. Alternative methods such as additional network 1542 segmentation can be used to keep that growth within reason. 1544 15. Security Considerations 1546 Based on how a MUD-URL is emitted, a Thing may be able to lie about 1547 what it is, thus gaining additional network access. There are 1548 several means to limit risk in this case. The most obvious is to 1549 only believe Things that make use of certificate-based authentication 1550 such as IEEE 802.1AR certificates. When those certificates are not 1551 present, Things claiming to be of a certain manufacturer SHOULD NOT 1552 be included in that manufacturer grouping without additional 1553 validation of some form. This will occur when it makes use of 1554 primitives such as "manufacturer" for the purpose of accessing Things 1555 of a particular type. Similarly, network management systems may be 1556 able to fingerprint the Thing. In such cases, the MUD-URL can act as 1557 a classifier that can be proven or disproven. Fingerprinting may 1558 have other advantages as well: when 802.1AR certificates are used, 1559 because they themselves cannot change, fingerprinting offers the 1560 opportunity to add artificats to the MUD-URL. The meaning of such 1561 artifacts is left as future work. 1563 Network management systems SHOULD NOT accept a usage description for 1564 a Thing with the same MAC address that has indicated a change of 1565 authority without some additional validation (such as review by a 1566 network administrator). New Things that present some form of 1567 unauthenticated MUD URL SHOULD be validated by some external means 1568 when they would be otherwise be given increased network access. 1570 It may be possible for a rogue manufacturer to inappropriately 1571 exercise the MUD file parser, in order to exploit a vulnerability. 1572 There are three recommended approaches to address this threat. The 1573 first is to validate the signature of the MUD file. The second is to 1574 have a system do a primary scan of the file to ensure that it is both 1575 parseable and believable at some level. MUD files will likely be 1576 relatively small, to start with. The number of ACEs used by any 1577 given Thing should be relatively small as well. It may also be 1578 useful to limit retrieval of MUD URLs to only those sites that are 1579 known to have decent web or domain reputations. 1581 Use of a URL necessitates the use of domain names. If a domain name 1582 changes ownership, the new owner of that domain may be able to 1583 provide MUD files that MUD controllers would consider valid. There 1584 are a few approaches that can mitigate this attack. First, MUD 1585 controllers SHOULD cache certificates used by the MUD file server. 1586 When a new certificate is retrieved for whatever reason, the MUD 1587 controller should check to see if ownership of the domain has 1588 changed. A fair programmatic approximation of this is when the name 1589 servers for the domain have changed. If the actual MUD file has 1590 changed, the controller MAY check the WHOIS database to see if 1591 registration ownership of a domain has changed. If a change has 1592 occured, or if for some reason it is not possible to determine 1593 whether ownership has changed, further review may be warranted. 1594 Note, this remediation does not take into account the case of a Thing 1595 that was produced long ago and only recently fielded, or the case 1596 where a new MUD controller has been installed. 1598 It may not be possible for a MUD controller to retrieve a MUD file at 1599 any given time. Should a MUD controller fail to retrieve a MUD file, 1600 it SHOULD consider the existing one safe to use, at least for a time. 1601 After some period, it SHOULD log that it has been unable to retrieve 1602 the file. There may be very good reasons for such failures, 1603 including the possibility that the MUD controller is in an off-line 1604 environment, the local Internet connection has failed, or the remote 1605 Internet connection has failed. It is also possible that an attacker 1606 is attempting to prevent onboarding of a device. It is a local 1607 deployment decision as to whether or not devices may be onboarded in 1608 the face of such failures. 1610 The release of a MUD URL by a Thing reveals what the Thing is, and 1611 provides an attacker with guidance on what vulnerabilities may be 1612 present. 1614 While the MUD URL itself is not intended to be unique to a specific 1615 Thing, the release of the URL may aid an observer in identifying 1616 individuals when combined with other information. This is a privacy 1617 consideration. 1619 In addressing both of these concerns, implementors should take into 1620 account what other information they are advertising through 1621 mechanisms such as mDNS[RFC6872], how a Thing might otherwise be 1622 identified, perhaps through how it behaves when it is connected to 1623 the network, whether a Thing is intended to be used by individuals or 1624 carry personal identifying information, and then apply appropriate 1625 data minimization techniques. One approach is to make use of TEAP 1626 [RFC7170] as the means to share information with authorized 1627 components in the network. Network Things may also assist in 1628 limiting access to the MUD-URL through the use of mechanisms such as 1629 DHCPv6-Shield [RFC7610]. 1631 Please note that the security considerations mentioned in Section 4.7 1632 of [I-D.ietf-netmod-rfc6087bis] are not applicable in this case 1633 because the YANG serialization is not intended to be accessed via 1634 NETCONF. However, for those who try to instantiate this model in a 1635 Thing via NETCONF, all objects in each model in this draft exhibit 1636 similar security characteristics as [I-D.ietf-netmod-acl-model]. The 1637 basic purpose of MUD is to configure access, and so by its very 1638 nature can be disruptive if used by unauthorized parties. 1640 16. IANA Considerations 1642 16.1. YANG Module Registrations 1644 The following YANG modules are requested to be registred in the "IANA 1645 Module Names" registry: 1647 The ietf-mud module: 1649 o Name: ietf-mud 1651 o XML Namespace: urn:ietf:params:xml:ns:yang:ietf-mud 1653 o Prefix: ief-mud 1655 o Reference: This memo 1657 The ietf-acldns module: 1659 o Name: ietf-acldns 1661 o XML Namespace: urn:ietf:params:xml:ns:yang:ietf-acldns 1663 o Prefix: ietf-acldns 1665 o Reference: This memo 1667 16.2. DHCPv4 and DHCPv6 Options 1669 The IANA has allocated option 161 in the Dynamic Host Configuration 1670 Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry 1671 for the MUD DHCPv4 option. 1673 IANA is requested to allocated the DHCPv4 and v6 options as specified 1674 in Section 9. 1676 16.3. PKIX Extensions 1678 IANA is kindly requested to make the following assignments for: 1680 o The MUDURLExtnModule-2016 ASN.1 module in the "SMI Security for 1681 PKIX Module Identifier" registry (1.3.6.1.5.5.7.0). 1683 o id-pe-mud-url object identifier from the "SMI Security for PKIX 1684 Certificate Extension" registry (1.3.6.1.5.5.7.1). 1686 The use fo these values is specified in Section 10. 1688 16.4. Well Known URI Suffix 1690 The IANA has allocated the URL suffix of "mud" as follows: 1692 o URI Suffix: "mud" o Specification documents: this document o 1693 Related information: n/a 1695 16.5. MIME Media-type Registration for MUD files 1697 The following media-type is defined for transfer of MUD file: 1699 o Type name: application 1700 o Subtype name: mud+json 1701 o Required parameters: n/a 1702 o Optional parameters: n/a 1703 o Encoding considerations: 8bit; application/mud+json values 1704 are represented as a JSON object; UTF-8 encoding SHOULD be 1705 employed. 1706 o Security considerations: See {{secon}} of this document. 1707 o Interoperability considerations: n/a 1708 o Published specification: this document 1709 o Applications that use this media type: MUD controllers as 1710 specified by this document. 1711 o Fragment identifier considerations: n/a 1712 o Additional information: 1714 Magic number(s): n/a 1715 File extension(s): n/a 1716 Macintosh file type code(s): n/a 1718 o Person & email address to contact for further information: 1719 Eliot Lear , Ralph Droms 1720 o Intended usage: COMMON 1721 o Restrictions on usage: none 1722 o Author: 1723 Eliot Lear 1724 Ralph Droms 1725 o Change controller: IESG 1726 o Provisional registration? (standards tree only): No. 1728 16.6. LLDP IANA TLV Subtype Registry 1730 IANA is requested to create a new registry for IANA Link Layer 1731 Discovery Protocol (LLDP) TLV subtype values. The recommended policy 1732 for this registry is Expert Review. The maximum number of entries in 1733 the registry is 256. 1735 IANA is required to populate the initial registry with the value: 1737 LLDP subtype value = 1 (All the other 255 values should be initially 1738 marked as 'Unassigned'.) 1740 Description = the Manufacturer Usage Description (MUD) Uniform 1741 Resource Locator (URL) 1743 Reference = < this document > 1745 16.7. The MUD Well Known Universal Resource Name (URNs) 1747 The following parameter registry is requested to be added in 1748 accordance with [RFC3553] 1750 Registry name: "urn:ietf:params:mud" is requested. 1751 Specification: this document 1752 Repository: this document 1753 Index value: Encoded identically to a TCP/UDP port service 1754 name, as specified in Section 5.1 of [RFC6335] 1756 The following entries should be added to the "urn:ietf:params:mud" 1757 name space: 1759 "urn:ietf:params:mud:dns" refers to the service specified by 1760 [RFC1123]. "urn:ietf:params:mud:ntp" refers to the service specified 1761 by [RFC5905]. 1763 16.8. Extensions Registry 1765 The IANA is requested to establish a registry of extensions as 1766 follows: 1768 Registry name: MUD extensions registry 1769 Registry policy: Standards action 1770 Standard reference: document 1771 Extension name: UTF-8 encoded string, not to exceed 40 characters. 1773 Each extension MUST follow the rules specified in this specification. 1774 As is usual, the IANA issues early allocations based in accordance 1775 with [RFC7120]. 1777 17. Acknowledgments 1779 The authors would like to thank Einar Nilsen-Nygaard, who 1780 singlehandedly updated the model to match the updated ACL model, 1781 Bernie Volz, Tom Gindin, Brian Weis, Sandeep Kumar, Thorsten Dahm, 1782 John Bashinski, Steve Rich, Jim Bieda, Dan Wing, Joe Clarke, Henk 1783 Birkholz, Adam Montville, and Robert Sparks for their valuable advice 1784 and reviews. Russ Housley entirely rewrote Section 10 to be a 1785 complete module. Adrian Farrel provided the basis for privacy 1786 considerations text. Kent Watson provided a thorough review of the 1787 architecture and the YANG model. The remaining errors in this work 1788 are entirely the responsibility of the authors. 1790 18. References 1792 18.1. Normative References 1794 [I-D.ietf-anima-bootstrapping-keyinfra] 1795 Pritikin, M., Richardson, M., Behringer, M., Bjarnason, 1796 S., and K. Watsen, "Bootstrapping Remote Secure Key 1797 Infrastructures (BRSKI)", draft-ietf-anima-bootstrapping- 1798 keyinfra-07 (work in progress), July 2017. 1800 [I-D.ietf-netmod-acl-model] 1801 Jethanandani, M., Huang, L., Agarwal, S., and D. Blair, 1802 "Network Access Control List (ACL) YANG Data Model", 1803 draft-ietf-netmod-acl-model-12 (work in progress), 1804 September 2017. 1806 [IEEE8021AB] 1807 Institute for Electrical and Electronics Engineers, "IEEE 1808 Standard for Local and Metropolitan Area Networks-- 1809 Station and Media Access Control Connectivity Discovery", 1810 n.d.. 1812 [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - 1813 Application and Support", STD 3, RFC 1123, 1814 DOI 10.17487/RFC1123, October 1989, . 1817 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1818 Requirement Levels", BCP 14, RFC 2119, 1819 DOI 10.17487/RFC2119, March 1997, . 1822 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 1823 RFC 2131, DOI 10.17487/RFC2131, March 1997, 1824 . 1826 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 1827 DOI 10.17487/RFC2818, May 2000, . 1830 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1831 C., and M. Carney, "Dynamic Host Configuration Protocol 1832 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1833 2003, . 1835 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 1836 Levkowetz, Ed., "Extensible Authentication Protocol 1837 (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004, 1838 . 1840 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1841 Resource Identifier (URI): Generic Syntax", STD 66, 1842 RFC 3986, DOI 10.17487/RFC3986, January 2005, 1843 . 1845 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource 1846 Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987, 1847 January 2005, . 1849 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1850 Housley, R., and W. Polk, "Internet X.509 Public Key 1851 Infrastructure Certificate and Certificate Revocation List 1852 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, 1853 . 1855 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 1856 RFC 5652, DOI 10.17487/RFC5652, September 2009, 1857 . 1859 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 1860 "Network Time Protocol Version 4: Protocol and Algorithms 1861 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 1862 . 1864 [RFC6020] Bjorklund, M., Ed., "YANG - A Data Modeling Language for 1865 the Network Configuration Protocol (NETCONF)", RFC 6020, 1866 DOI 10.17487/RFC6020, October 2010, . 1869 [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. 1870 Cheshire, "Internet Assigned Numbers Authority (IANA) 1871 Procedures for the Management of the Service Name and 1872 Transport Protocol Port Number Registry", BCP 165, 1873 RFC 6335, DOI 10.17487/RFC6335, August 2011, 1874 . 1876 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", 1877 RFC 6991, DOI 10.17487/RFC6991, July 2013, 1878 . 1880 [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code 1881 Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January 1882 2014, . 1884 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 1885 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 1886 BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014, 1887 . 1889 [RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield: 1890 Protecting against Rogue DHCPv6 Servers", BCP 199, 1891 RFC 7610, DOI 10.17487/RFC7610, August 2015, 1892 . 1894 18.2. Informative References 1896 [FW95] Chapman, D. and E. Zwicky, "Building Internet Firewalls", 1897 January 1995. 1899 [I-D.ietf-netmod-rfc6087bis] 1900 Bierman, A., "Guidelines for Authors and Reviewers of YANG 1901 Data Model Documents", draft-ietf-netmod-rfc6087bis-14 1902 (work in progress), September 2017. 1904 [IEEE8021AR] 1905 Institute for Electrical and Electronics Engineers, 1906 "Secure Device Identity", 1998. 1908 [ISO.8601.1988] 1909 International Organization for Standardization, "Data 1910 elements and interchange formats - Information interchange 1911 - Representation of dates and times", ISO Standard 8601, 1912 June 1988. 1914 [RFC1984] IAB and IESG, "IAB and IESG Statement on Cryptographic 1915 Technology and the Internet", BCP 200, RFC 1984, 1916 DOI 10.17487/RFC1984, August 1996, . 1919 [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: 1920 Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, 1921 . 1923 [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An 1924 IETF URN Sub-namespace for Registered Protocol 1925 Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June 1926 2003, . 1928 [RFC6092] Woodyatt, J., Ed., "Recommended Simple Security 1929 Capabilities in Customer Premises Equipment (CPE) for 1930 Providing Residential IPv6 Internet Service", RFC 6092, 1931 DOI 10.17487/RFC6092, January 2011, . 1934 [RFC6872] Gurbani, V., Ed., Burger, E., Ed., Anjali, T., Abdelnur, 1935 H., and O. Festor, "The Common Log Format (CLF) for the 1936 Session Initiation Protocol (SIP): Framework and 1937 Information Model", RFC 6872, DOI 10.17487/RFC6872, 1938 February 2013, . 1940 [RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and 1941 IETF Protocol and Documentation Usage for IEEE 802 1942 Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042, 1943 October 2013, . 1945 [RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna, 1946 "Tunnel Extensible Authentication Protocol (TEAP) Version 1947 1", RFC 7170, DOI 10.17487/RFC7170, May 2014, 1948 . 1950 [RFC7452] Tschofenig, H., Arkko, J., Thaler, D., and D. McPherson, 1951 "Architectural Considerations in Smart Object Networking", 1952 RFC 7452, DOI 10.17487/RFC7452, March 2015, 1953 . 1955 [RFC7488] Boucadair, M., Penno, R., Wing, D., Patil, P., and T. 1956 Reddy, "Port Control Protocol (PCP) Server Selection", 1957 RFC 7488, DOI 10.17487/RFC7488, March 2015, 1958 . 1960 Appendix A. Changes from Earlier Versions 1962 RFC Editor to remove this section prior to publication. 1964 Draft -08 to -09: * Resolution of Security Area review, IoT 1965 directorate review, GenART review, YANG doctors review. * change of 1966 YANG structure to address mandatory nodes. * Terminology cleanup. * 1967 specify out extra portion of MUD-URL. * consistency changes. * 1968 improved YANG descriptions. * Remove extra revisions. * Track ACL 1969 model changes. * Additional cautions on use of ACL model; further 1970 clarifications on extensions. 1972 Draft -07 to -08: 1974 o a number of editorials corrected. 1976 o definition of MUD file tweaked. 1978 Draft -06 to -07: 1980 o Examples updated. 1982 o Additional clarification for direction-initiated. 1984 o Additional implementation guidance given. 1986 Draft -06 to -07: 1988 o Update models to match new ACL model 1990 o extract directionality from the ACL, introducing a new device 1991 container. 1993 Draft -05 to -06: 1995 o Make clear that this is a component architecture (Polk and Watson) 1997 o Add order of operations (Watson) 1999 o Add extensions leaf-list (Pritikin) 2001 o Remove previous-mud-file (Watson) 2003 o Modify text in last-update (Watson) 2005 o Clarify local networks (Weis, Watson) 2007 o Fix contact info (Watson) 2009 o Terminology clarification (Weis) 2011 o Advice on how to handle LDevIDs (Watson) 2013 o Add deployment considerations (Watson) 2015 o Add some additional text about fingerprinting (Watson) 2017 o Appropriate references to 6087bis (Watson) 2019 o Change systeminfo to a URL to be referenced (Lear) 2021 Draft -04 to -05: * syntax error correction 2023 Draft -03 to -04: * Re-add my-controller 2024 Draft -02 to -03: * Additional IANA updates * Format correction in 2025 YANG. * Add reference to TEAP. 2027 Draft -01 to -02: * Update IANA considerations * Accept Russ Housley 2028 rewrite of X.509 text * Include privacy considerations text * Redo 2029 the URL limit. Still 255 bytes, but now stated in the URL 2030 definition. * Change URI registration to be under urn:ietf:params 2032 Draft -00 to -01: * Fix cert trust text. * change supportInformation 2033 to meta-info * Add an informational element in. * add urn registry 2034 and create first entry * add default elements 2036 Appendix B. Default MUD nodes 2038 What follows is a MUD file that permits DNS traffic to a controller 2039 that is registered with the URN "urn:ietf:params:mud:dns" and traffic 2040 NTP to a controller that is registered "urn:ietf:params:mud:ntp". 2041 This is considered the default behavior and the ACEs are in effect 2042 appended to whatever other ACEs. To block DNS or NTP one repeats the 2043 matching statement but replace "permit" with deny. Because ACEs are 2044 processed in the order they are received, the defaults would not be 2045 reached. A MUD controller might further decide to optimize to simply 2046 not include the defaults when they are overriden. 2048 The access-list component of the MUD entry is included below. 2050 { 2051 "ietf-access-control-list:access-lists": { 2052 "acl": [ 2053 { 2054 "acl-name": "mud-67390-v4to", 2055 "acl-type": "ipv4-acl", 2056 "aces": { 2057 "ace": [ 2058 { 2059 "rule-name": "ent0-todev", 2060 "matches": { 2061 "ietf-mud:mud-acl"{ 2062 "controller": "urn:ietf:params:mud:dns" 2063 }, 2064 "protocol": 17, 2065 "source-port-range": { 2066 "lower-port": 53, 2067 "upper-port": 53 2068 } 2069 }, 2070 "actions": { 2071 "permit": [ 2072 null 2073 ] 2074 } 2075 }, 2076 { 2077 "rule-name": "ent1-todev", 2078 "matches": { 2079 "ietf-mud:mud-acl"{ 2080 "controller": "urn:ietf:params:mud:ntp" 2081 }, 2082 "protocol": 17 2083 }, 2084 "actions": { 2085 "permit": [ 2086 null 2087 ] 2088 } 2089 } 2090 ] 2091 } 2092 }, 2093 { 2094 "acl-name": "mud-67390-v4fr", 2095 "acl-type": "ipv4-acl", 2096 "access-list-entries": { 2097 "ace": [ 2098 { 2099 "rule-name": "ent0-frdev", 2100 "matches": { 2101 "ietf-mud:mud-acl"{ 2102 "controller": "urn:ietf:params:mud:dns" 2103 }, 2104 "protocol": 17, 2105 "destination-port-range": { 2106 "lower-port": 53, 2107 "upper-port": 53 2108 } 2109 }, 2110 "actions": { 2111 "permit": [ 2112 null 2113 ] 2114 } 2115 }, 2116 { 2117 "rule-name": "ent1-frdev", 2118 "matches": { 2119 "ietf-mud:mud-acl"{ 2120 "controller": "urn:ietf:params:mud:ntp" 2121 }, 2122 "protocol": 17 2123 }, 2124 "actions": { 2125 "permit": [ 2126 null 2127 ] 2128 } 2129 } 2130 ] 2131 } 2132 }, 2133 { 2134 "acl-name": "mud-67390-v6to", 2135 "acl-type": "ipv6-acl", 2136 "aces": { 2137 "ace": [ 2138 { 2139 "rule-name": "ent0-todev", 2140 "matches": { 2141 "ietf-mud:mud-acl"{ 2142 "controller": "urn:ietf:params:mud:dns" 2143 }, 2144 "protocol": 17, 2145 "source-port-range": { 2146 "lower-port": 53, 2147 "upper-port": 53 2148 } 2149 }, 2150 "actions": { 2151 "permit": [ 2152 null 2153 ] 2154 } 2155 }, 2156 { 2157 "rule-name": "ent1-todev", 2158 "matches": { 2159 "ietf-mud:mud-acl"{ 2160 "controller": "urn:ietf:params:mud:ntp" 2161 }, 2162 "protocol": 17 2163 }, 2164 "actions": { 2165 "permit": [ 2166 null 2167 ] 2169 } 2170 } 2171 ] 2172 } 2173 }, 2174 { 2175 "acl-name": "mud-67390-v6fr", 2176 "acl-type": "ipv6-acl", 2177 "aces": { 2178 "ace": [ 2179 { 2180 "rule-name": "ent0-frdev", 2181 "matches": { 2182 "ietf-mud:mud-acl"{ 2183 "controller": "urn:ietf:params:mud:dns" 2184 }, 2185 "protocol": 17, 2186 "destination-port-range": { 2187 "lower-port": 53, 2188 "upper-port": 53 2189 } 2190 }, 2191 "actions": { 2192 "permit": [ 2193 null 2194 ] 2195 } 2196 }, 2197 { 2198 "rule-name": "ent1-frdev", 2199 "matches": { 2200 "ietf-mud:mud-acl"{ 2201 "controller": "urn:ietf:params:mud:ntp" 2202 }, 2203 "protocol": 17 2204 }, 2205 "actions": { 2206 "permit": [ 2207 null 2208 ] 2209 } 2210 } 2211 ] 2212 } 2213 } 2214 ] 2215 } 2217 Appendix C. A Sample Extension: DETNET-indicator 2219 In this sample extension we augment the core MUD model to indicate 2220 whether the device implements DETNET. If a device later attempts to 2221 make use of DETNET, an notification or exception might be generated. 2222 Note that this example is intended only for illustrative purposes. 2224 Extension Name: "Example-Extension" (to be used in the extensions list) 2225 Standard: this document (but do not register the example) 2227 This extension augments the MUD model to include a single node, using 2228 the following sample module that has the following tree structure: 2230 module: ietf-mud-detext-example 2231 augment /ietf-mud:mud: 2232 +--rw is-detnet-required? boolean 2234 The model is defined as follows: 2236 file "ietf-mud-detext-example@2016-09-07.yang" 2237 module ietf-mud-detext-example { 2238 yang-version 1.1; 2239 namespace "urn:ietf:params:xml:ns:yang:ietf-mud-detext-example"; 2240 prefix ietf-mud-detext-example; 2242 import ietf-mud { 2243 prefix ietf-mud; 2244 } 2246 organization 2247 "IETF OPSAWG (Ops Area) Working Group"; 2248 contact 2249 "WG Web: http://tools.ietf.org/wg/opsawg/ 2250 WG List: opsawg@ietf.org 2251 Author: Eliot Lear 2252 lear@cisco.com 2253 Author: Ralph Droms 2254 rdroms@gmail.com 2255 Author: Dan Romascanu 2256 dromasca@gmail.com 2258 "; 2259 description 2260 "Sample extension to a MUD module to indicate a need 2261 for DETNET support."; 2263 revision 2017-09-05 { 2264 description 2265 "Initial revision."; 2266 reference 2267 "RFC XXXX: Manufacturer Usage Description 2268 Specification"; 2269 } 2271 augment "/ietf-mud:mud" { 2272 description 2273 "This adds a simple extension for a manufacturer 2274 to indicate whether DETNET is required by a 2275 device."; 2276 leaf is-detnet-required { 2277 type boolean; 2278 description 2279 "This value will equal true if a device requires 2280 detnet to properly function"; 2281 } 2282 } 2283 } 2284 2286 Using the previous example, we now show how the extension would be 2287 expressed: 2289 { 2290 "ietf-mud:mud": { 2291 "mud-url": "https://bms.example.com/.well-known/mud/v1/lightbulb2", 2292 "last-update": "2017-08-30T15:48:42+02:00", 2293 "systeminfo": "https://bms.example.com/descriptions/lightbulb2", 2294 "cache-validity": 48, 2295 "extensions": [ 2296 "ietf-mud-detext-example" 2297 ], 2298 "ietf-mud-detext-example:is-detnet-required": "false", 2299 "from-device-policy": { 2300 "access-lists": { 2301 "access-list": [ 2302 { 2303 "acl-name": "mud-16595-v6fr", 2304 "acl-type": "ietf-access-control-list:ipv6-acl" 2305 } 2306 ] 2307 } 2308 }, 2309 "to-device-policy": { 2310 "access-lists": { 2311 "access-list": [ 2312 { 2313 "acl-name": "mud-16595-v4to", 2314 "acl-type": "ietf-access-control-list:ipv6-acl" 2315 } 2316 ] 2317 } 2318 } 2319 }, 2320 "ietf-access-control-list:access-lists": { 2321 "acl": [ 2322 { 2323 "acl-name": "mud-16595-v6to", 2324 "acl-type": "ipv6-acl", 2325 "access-list-entries": { 2326 "ace": [ 2327 { 2328 "rule-name": "cl0-todev", 2329 "matches": { 2330 "ipv4-acl": { 2331 "ietf-acldns:src-dnsname": "service.bms.example.com" 2332 }, 2333 "protocol": 6, 2334 "source-port-range": { 2335 "lower-port": 443, 2336 "upper-port": 443 2337 }, 2338 "tcp-acl": { 2339 "ietf-mud:direction-initiated": "to-device" 2340 } 2341 }, 2342 "actions": { 2343 "permit": [ 2344 null 2345 ] 2346 } 2347 } 2348 ] 2349 } 2350 }, 2351 { 2352 "acl-name": "mud-16595-v6fr", 2353 "acl-type": "ipv6-acl", 2354 "aces": { 2355 "ace": [ 2356 { 2357 "rule-name": "cl0-frdev", 2358 "matches": { 2359 "ipv6-acl": { 2360 "ietf-acldns:dst-dnsname": "service.bms.example.com" 2361 }, 2362 "protocol": 6, 2363 "destination-port-range": { 2364 "lower-port": 443, 2365 "upper-port": 443 2366 }, 2367 "tcp-acl": { 2368 "ietf-mud:direction-initiated": "to-device" 2369 } 2370 }, 2371 "actions": { 2372 "permit": [ 2373 null 2374 ] 2375 } 2376 } 2377 ] 2378 } 2379 } 2380 ] 2381 } 2382 } 2384 Authors' Addresses 2386 Eliot Lear 2387 Cisco Systems 2388 Richtistrasse 7 2389 Wallisellen CH-8304 2390 Switzerland 2392 Phone: +41 44 878 9200 2393 Email: lear@cisco.com 2395 Ralph Droms 2397 Phone: +1 978 376 3731 2398 Email: rdroms@gmail.com 2400 Dan Romascanu 2402 Phone: +972 54 5555347 2403 Email: dromasca@gmail.com