idnits 2.17.1 draft-ietf-opsawg-mud-16.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 1079 has weird spacing: '...ecified model...' == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: Note when using either of these with a MUD file, because access is associated with a particular Thing, MUD files MUST not contain either a src-dnsname in an ACL associated with from-device-policy or a dst-dnsname associated with to-device-policy. -- The document date (February 20, 2018) is 2257 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(See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-21) exists of draft-ietf-netmod-acl-model-16 -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE8021AB' ** Obsolete normative reference: RFC 2618 (Obsoleted by RFC 4668) ** Obsolete normative reference: RFC 2818 (Obsoleted by RFC 9110) ** Obsolete normative reference: RFC 3315 (Obsoleted by RFC 8415) ** Obsolete normative reference: RFC 7230 (Obsoleted by RFC 9110, RFC 9112) ** Obsolete normative reference: RFC 7231 (Obsoleted by RFC 9110) == Outdated reference: A later version (-20) exists of draft-ietf-netmod-rfc6087bis-17 -- Obsolete informational reference (is this intentional?): RFC 7042 (Obsoleted by RFC 9542) -- Obsolete informational reference (is this intentional?): RFC 7223 (Obsoleted by RFC 8343) Summary: 5 errors (**), 0 flaws (~~), 5 warnings (==), 4 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: August 24, 2018 6 D. Romascanu 7 February 20, 2018 9 Manufacturer Usage Description Specification 10 draft-ietf-opsawg-mud-16 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 https://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 August 24, 2018. 41 Copyright Notice 43 Copyright (c) 2018 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 (https://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. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 62 1.4. Determining Intended Use . . . . . . . . . . . . . . . . 6 63 1.5. Finding A Policy: The MUD URL . . . . . . . . . . . . . . 6 64 1.6. Processing of the MUD URL . . . . . . . . . . . . . . . . 7 65 1.7. Types of Policies . . . . . . . . . . . . . . . . . . . . 7 66 1.8. The Manufacturer Usage Description Architecture . . . . . 9 67 1.9. Order of operations . . . . . . . . . . . . . . . . . . . 11 68 2. The MUD Model and Semantic Meaning . . . . . . . . . . . . . 11 69 2.1. The IETF-MUD YANG Module . . . . . . . . . . . . . . . . 13 70 3. Data Node Definitions . . . . . . . . . . . . . . . . . . . . 14 71 3.1. mud-version . . . . . . . . . . . . . . . . . . . . . . . 14 72 3.2. to-device-policy and from-device-policy containers . . . 15 73 3.3. last-update . . . . . . . . . . . . . . . . . . . . . . . 15 74 3.4. cache-validity . . . . . . . . . . . . . . . . . . . . . 15 75 3.5. is-supported . . . . . . . . . . . . . . . . . . . . . . 15 76 3.6. systeminfo . . . . . . . . . . . . . . . . . . . . . . . 15 77 3.7. mfg-name, hardware-rev, software-rev, model-name 78 firmware-rev . . . . . . . . . . . . . . . . . . . . . . 16 79 3.8. extensions . . . . . . . . . . . . . . . . . . . . . . . 16 80 3.9. manufacturer . . . . . . . . . . . . . . . . . . . . . . 16 81 3.10. same-manufacturer . . . . . . . . . . . . . . . . . . . . 16 82 3.11. model . . . . . . . . . . . . . . . . . . . . . . . . . . 16 83 3.12. local-networks . . . . . . . . . . . . . . . . . . . . . 17 84 3.13. controller . . . . . . . . . . . . . . . . . . . . . . . 17 85 3.14. my-controller . . . . . . . . . . . . . . . . . . . . . . 17 86 3.15. direction-initiated . . . . . . . . . . . . . . . . . . . 17 87 4. Processing of the MUD file . . . . . . . . . . . . . . . . . 18 88 5. What does a MUD URL look like? . . . . . . . . . . . . . . . 18 89 6. The MUD YANG Model . . . . . . . . . . . . . . . . . . . . . 19 90 7. The Domain Name Extension to the ACL Model . . . . . . . . . 25 91 7.1. src-dnsname . . . . . . . . . . . . . . . . . . . . . . . 26 92 7.2. dst-dnsname . . . . . . . . . . . . . . . . . . . . . . . 26 93 7.3. The ietf-acldns Model . . . . . . . . . . . . . . . . . . 26 94 8. MUD File Example . . . . . . . . . . . . . . . . . . . . . . 27 95 9. The MUD URL DHCP Option . . . . . . . . . . . . . . . . . . . 30 96 9.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 30 97 9.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 31 98 9.3. Relay Requirements . . . . . . . . . . . . . . . . . . . 31 99 10. The Manufacturer Usage Description (MUD) URL X.509 Extension 31 100 11. The Manufacturer Usage Description LLDP extension . . . . . . 33 101 12. Creating and Processing of Signed MUD Files . . . . . . . . . 35 102 12.1. Creating a MUD file signature . . . . . . . . . . . . . 35 103 12.2. Verifying a MUD file signature . . . . . . . . . . . . . 35 104 13. Extensibility . . . . . . . . . . . . . . . . . . . . . . . . 36 105 14. Deployment Considerations . . . . . . . . . . . . . . . . . . 36 106 15. Security Considerations . . . . . . . . . . . . . . . . . . . 37 107 16. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 39 108 16.1. YANG Module Registrations . . . . . . . . . . . . . . . 39 109 16.2. DHCPv4 and DHCPv6 Options . . . . . . . . . . . . . . . 40 110 16.3. PKIX Extensions . . . . . . . . . . . . . . . . . . . . 40 111 16.4. MIME Media-type Registration for MUD files . . . . . . . 40 112 16.5. LLDP IANA TLV Subtype Registry . . . . . . . . . . . . . 41 113 16.6. The MUD Well Known Universal Resource Name (URNs) . . . 42 114 16.7. Extensions Registry . . . . . . . . . . . . . . . . . . 42 115 17. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42 116 18. References . . . . . . . . . . . . . . . . . . . . . . . . . 43 117 18.1. Normative References . . . . . . . . . . . . . . . . . . 43 118 18.2. Informative References . . . . . . . . . . . . . . . . . 45 119 Appendix A. Changes from Earlier Versions . . . . . . . . . . . 47 120 Appendix B. Default MUD nodes . . . . . . . . . . . . . . . . . 50 121 Appendix C. A Sample Extension: DETNET-indicator . . . . . . . . 55 122 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 58 124 1. Introduction 126 The Internet has largely been constructed for general purpose 127 computers, those devices that may be used for a purpose that is 128 specified by those who own the device. [RFC1984] presumed that an 129 end device would be most capable of protecting itself. This made 130 sense when the typical device was a workstation or a mainframe, and 131 it continues to make sense for general purpose computing devices 132 today, including laptops, smart phones, and tablets. 134 [RFC7452] discusses design patterns for, and poses questions about, 135 smart objects. Let us then posit a group of objects that are 136 specifically not general purpose computers. These devices, which 137 this memo refers to as Things, have a specific purpose. By 138 definition, therefore, all other uses are not intended. The 139 combination of these two statements can be restated as a manufacturer 140 usage description (MUD) that can be applied at various points within 141 a network. 143 We use the notion of "manufacturer" loosely in this context to refer 144 to the entity or organization that will state how a device is 145 intended to be used. For example, in the context of a lightbulb, 146 this might indeed be the lightbulb manufacturer. In the context of a 147 smarter device that has a built in Linux stack, it might be an 148 integrator of that device. The key points are that the device itself 149 is assumed to serve a limited purpose, and that there may exist an 150 organization in the supply chain of that device that will take 151 responsibility for informing the network about that purpose. 153 The intent of MUD is to provide the following: 155 o Substantially reduce the threat surface on a device entering a 156 network to those communications intended by the manufacturer. 158 o Provide a means to scale network policies to the ever-increasing 159 number of types of devices in the network. 161 o Provide a means to address at least some vulnerabilities in a way 162 that is faster than the time it might take to update systems. 163 This will be particularly true for systems that are no longer 164 supported by their manufacturer. 166 o Keep the cost of implementation of such a system to the bare 167 minimum. 169 o Provide a means of extensibility for manufacturers to express 170 other device capabilities or requirements. 172 MUD consists of three architectural building blocks: 174 o A URL that is can be used to locate a description; 176 o The description itself, including how it is interpreted, and; 178 o A means for local network management systems to retrieve the 179 description. 181 In this specification we describe each of these building blocks and 182 how they are intended to be used together. However, they may also be 183 used separately, independent of this specification, by local 184 deployments for their own purposes. 186 1.1. What MUD Doesn't Do 188 MUD is not intended to address network authorization of general 189 purpose computers, as their manufacturers cannot envision a specific 190 communication pattern to describe. In addition, even those devices 191 that have a single or small number of uses might have very broad 192 communication patterns. MUD on its own is not for them either. 194 Although MUD can provide network administrators with some additional 195 protection when device vulnerabilities exist, it will never replace 196 the need for manufacturers to patch vulnerabilities. 198 Finally, no matter what the manufacturer specifies in a MUD file, 199 these are not directives, but suggestions. How they are instantiated 200 locally will depend on many factors and will be ultimately up to the 201 local network administrator, who must decide what is appropriate in a 202 given circumstances. 204 1.2. A Simple Example 206 A light bulb is intended to light a room. It may be remotely 207 controlled through the network, and it may make use of a rendezvous 208 service of some form that an application on a smart phone. What we 209 can say about that light bulb, then, is that all other network access 210 is unwanted. It will not contact a news service, nor speak to the 211 refrigerator, and it has no need of a printer or other devices. It 212 has no social networking friends. Therefore, an access list applied 213 to it that states that it will only connect to the single rendezvous 214 service will not impede the light bulb in performing its function, 215 while at the same time allowing the network to provide both it and 216 other devices an additional layer of protection. 218 1.3. Terminology 220 MUD: manufacturer usage description. 222 MUD file: a file containing YANG-based JSON that describes a Thing 223 and associated suggested specific network behavior. 225 MUD file server: a web server that hosts a MUD file. 227 MUD controller: the system that requests and receives the MUD file 228 from the MUD server. After it has processed a MUD file, it may 229 direct changes to relevant network elements. 231 MUD URL: a URL that can be used by the MUD controller to receive the 232 MUD file. 234 Thing: the device emitting a MUD URL. 236 Manufacturer: the entity that configures the Thing to emit the MUD 237 URL and the one who asserts a recommendation in a MUD file. The 238 manufacturer might not always be the entity that constructs a 239 Thing. It could, for instance, be a systems integrator, or even a 240 component provider. 242 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 243 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 244 document are to be interpreted as described in [RFC2119]. 246 1.4. Determining Intended Use 248 The notion of intended use is in itself not new. Network 249 administrators apply access lists every day to allow for only such 250 use. This notion of white listing was well described by Chapman and 251 Zwicky in [FW95]. Profiling systems that make use of heuristics to 252 identify types of systems have existed for years as well. 254 A Thing could just as easily tell the network what sort of access it 255 requires without going into what sort of system it is. This would, 256 in effect, be the converse of [RFC7488]. In seeking a general 257 purpose solution, however, we assume that a device has so few 258 capabilities that it will implement the least necessary capabilities 259 to function properly. This is a basic economic constraint. Unless 260 the network would refuse access to such a device, its developers 261 would have no reason to provide the network any information. To 262 date, such an assertion has held true. 264 1.5. Finding A Policy: The MUD URL 266 Our work begins with the device emitting a Universal Resource Locator 267 (URL) [RFC3986]. This URL serves both to classify the device type 268 and to provide a means to locate a policy file. 270 MUD URLs MUST use the HTTPS scheme [RFC7230]. 272 In this memo three means are defined to emit the MUD URL, as follows: 274 o A DHCP option[RFC2131],[RFC3315] that the DHCP client uses to 275 inform the DHCP server. The DHCP server may take further actions, 276 such as retrieve the URL or otherwise pass it along to network 277 management system or controller. 279 o An X.509 constraint. The IEEE has developed [IEEE8021AR] that 280 provides a certificate-based approach to communicate device 281 characteristics, which itself relies on [RFC5280]. The MUD URL 282 extension is non-critical, as required by IEEE 802.1AR. Various 283 means may be used to communicate that certificate, including 284 Tunnel Extensible Authentication Protocol (TEAP) [RFC7170]. 286 o Finally, a Link Layer Discovery Protocol (LLDP) frame is defined 287 [IEEE8021AB]. 289 It is possible that there may be other means for a MUD URL to be 290 learned by a network. For instance, some devices may already be 291 fielded or have very limited ability to communicate a MUD URL, and 292 yet can be identified through some means, such as a serial number or 293 a public key. In these cases, manufacturers may be able to map those 294 identifiers to particular MUD URLs (or even the files themselves). 295 Similarly, there may be alternative resolution mechanisms available 296 for situations where Internet connectivity is limited or does not 297 exist. Such mechanisms are not described in this memo, but are 298 possible. Implementors should allow for this sort of flexibility of 299 how MUD URLs may be learned. 301 1.6. Processing of the MUD URL 303 MUD controllers that are able to do so SHOULD retrieve MUD URLs and 304 signature files as per [RFC7230], using the GET method [RFC7231]. 305 They MUST validate the certificate using the rules in [RFC2618], 306 Section 3.1. 308 Requests for MUD URLs SHOULD include an "Accept" header ([RFC7231], 309 Section 5.3.2) containing "application/mud+json", an "Accept- 310 Language" header ([RFC7231], Section 5.3.5), and a "User-Agent" 311 header ([RFC7231], Section 5.5.3). 313 MUD controllers SHOULD automatically process 3xx response status 314 codes. 316 If a MUD controller is not able to fetch a MUD URL, other means MAY 317 be used to import MUD files and associated signature files. So long 318 as the signature of the file can be validated, the file can be used. 319 In such environments, controllers SHOULD warn administrators when 320 cache-validity expiry is approaching so that they may check for new 321 files. 323 1.7. Types of Policies 325 When the MUD URL is resolved, the MUD controller retrieves a file 326 that describes what sort of communications a device is designed to 327 have. The manufacturer may specify either specific hosts for cloud 328 based services or certain classes for access within an operational 329 network. An example of a class might be "devices of a specified 330 manufacturer type", where the manufacturer type itself is indicated 331 simply by the authority component (e.g, the domain name) of the MUD 332 URL. Another example might be to allow or disallow local access. 333 Just like other policies, these may be combined. For example: 335 o Allow access to devices of the same manufacturer 336 o Allow access to and from controllers via Constrained Application 337 Protocol (COAP)[RFC7252] 339 o Allow access to local DNS/NTP 341 o Deny all other access 343 A printer might have a description that states: 345 o Allow access for port IPP or port LPD 347 o Allow local access for port HTTP 349 o Deny all other access 351 In this way anyone can print to the printer, but local access would 352 be required for the management interface. 354 The files that are retrieved are intended to be closely aligned to 355 existing network architectures so that they are easy to deploy. We 356 make use of YANG [RFC7950] because of the time and effort spent to 357 develop accurate and adequate models for use by network devices. 358 JSON is used as a serialization for compactness and readability, 359 relative to XML. Other formats may be chosen with later versions of 360 MUD. 362 While the policy examples given here focus on access control, this is 363 not intended to be the sole focus. By structuring the model 364 described in this document with clear extension points, other 365 descriptions could be included. One that often comes to mind is 366 quality of service. 368 The YANG modules specified here are extensions of 369 [I-D.ietf-netmod-acl-model]. The extensions to this model allow for 370 a manufacturer to express classes of systems that a manufacturer 371 would find necessary for the proper function of the device. Two 372 modules are specified. The first module specifies a means for domain 373 names to be used in ACLs so that devices that have their controllers 374 in the cloud may be appropriately authorized with domain names, where 375 the mapping of those names to addresses may rapidly change. 377 The other module abstracts away IP addresses into certain classes 378 that are instantiated into actual IP addresses through local 379 processing. Through these classes, manufacturers can specify how the 380 device is designed to communicate, so that network elements can be 381 configured by local systems that have local topological knowledge. 382 That is, the deployment populates the classes that the manufacturer 383 specifies. The abstractions below map to zero or more hosts, as 384 follows: 386 Manufacturer: A device made by a particular manufacturer, as 387 identified by the authority component of its MUD URL 389 same-manufacturer: Devices that have the same authority component of 390 their MUD URL. 392 controller: Devices that the local network administrator admits to 393 the particular class. 395 my-controller: Devices associated with the MUD URL of a device that 396 the administrator admits. 398 local: The class of IP addresses that are scoped within some 399 administrative boundary. By default it is suggested that this be 400 the local subnet. 402 The "manufacturer" classes can be easily specified by the 403 manufacturer, whereas controller classes are initially envisioned to 404 be specified by the administrator. 406 Because manufacturers do not know who will be using their devices, it 407 is important for functionality referenced in usage descriptions to be 408 relatively ubiquitous and mature. For these reasons only a limited 409 subset YANG-based configuration is permitted in a MUD file. 411 1.8. The Manufacturer Usage Description Architecture 413 With these components laid out we now have the basis for an 414 architecture. This leads us to ASCII art. 416 ....................................... 417 . ____________ . _____________ 418 . | | . | | 419 . | MUD |-->get URL-->| MUD | 420 . | Controller | .(https) | File Server | 421 . End system network |____________|<-MUD file<-<|_____________| 422 . . . 423 . . . 424 . _______ _________ . 425 .| | (dhcp et al) | router | . 426 .| Thing |---->MUD URL-->| or | . 427 .|_______| | switch | . 428 . |_________| . 429 ....................................... 431 Figure 1: MUD Architecture 433 In the above diagram, the switch or router collects MUD URLs and 434 forwards them to the MUD controller (a network management system) for 435 processing. This happens in different ways, depending on how the URL 436 is communicated. For instance, in the case of DHCP, the DHCP server 437 might receive the URL and then process it. In the case of IEEE 438 802.1X, the switch would carry the URL via a certificate to the 439 authentication server via EAP over Radius[RFC3748], which would then 440 process it. One method to do this is TEAP, described in [RFC7170]. 441 The certificate extension is described below. 443 The information returned by the MUD file server (a web server) is 444 valid for the duration of the Thing's connection, or as specified in 445 the description. Thus if the Thing is disconnected, any associated 446 configuration in the switch can be removed. Similarly, from time to 447 time the description may be refreshed, based on new capabilities or 448 communication patterns or vulnerabilities. 450 The web server is typically run by or on behalf of the manufacturer. 451 Its domain name is that of the authority found in the MUD URL. For 452 legacy cases where Things cannot emit a URL, if the switch is able to 453 determine the appropriate URL, it may proxy it, the trivial cases 454 being a hardcoded MUD-URL on a switch port, or a mapping from some 455 available identifier such as an L2 address or certificate hash to a 456 MUD-URL. 458 The role of the MUD controller in this environment is to do the 459 following: 461 o receive MUD URLs, 463 o fetch MUD files, 464 o translate abstractions in the MUD files to specific network 465 element configuration, 467 o maintain and update any required mappings of the abstractions, and 469 o update network elements with appropriate configuration. 471 A MUD controller may be a component of a AAA or network management 472 system. Communication within those systems and from those systems to 473 network elements is beyond the scope of this memo. 475 1.9. Order of operations 477 As mentioned above, MUD contains architectural building blocks, and 478 so order of operation may vary. However, here is one clear intended 479 example: 481 1. Thing emits URL. 483 2. That URL is forwarded to a MUD controller by the nearest switch 484 (how this happens depends on the way in which the MUD URL is 485 emitted). 487 3. The MUD controller retrieves the MUD file and signature from the 488 MUD file server, assuming it doesn't already have copies. After 489 validating the signature, it may test the URL against a web or 490 domain reputation service, and it may test any hosts within the 491 file against those reputation services, as it deems fit. 493 4. The MUD controller may query the administrator for permission to 494 add the Thing and associated policy. If the Thing is known or 495 the Thing type is known, it may skip this step. 497 5. The MUD controller instantiates local configuration based on the 498 abstractions defined in this document. 500 6. The MUD controller configures the switch nearest the Thing. 501 Other systems may be configured as well. 503 7. When the Thing disconnects, policy is removed. 505 2. The MUD Model and Semantic Meaning 507 A MUD file consists of a YANG model that has been serialized in JSON 508 [RFC7951]. For purposes of MUD, the nodes that can be modified are 509 access lists as augmented by this model. The MUD file is limited to 510 the serialization of only the following YANG schema: 512 o ietf-access-control-list [I-D.ietf-netmod-acl-model] 514 o ietf-mud (this document) 516 o ietf-acldns (this document) 518 Extensions may be used to add additional schema. This is described 519 further on. 521 To provide the widest possible deployment, publishers of MUD files 522 SHOULD make use of the abstractions in this memo and avoid the use of 523 IP addresses. A MUD controller SHOULD NOT automatically implement 524 any MUD file that contains IP addresses, especially those that might 525 have local significance. The addressing of one side of an access 526 list is implicit, based on whether it is applied as to-device-policy 527 or from-device-policy. 529 With the exceptions of "name" of the ACL, "type", "name" of the ACE, 530 and TCP and UDP source and destination port information, publishers 531 of MUD files SHOULD limit the use of ACL model leaf nodes expressed 532 to those found in this specification. Absent any extensions, MUD 533 files are assumed to implement only the following ACL model features: 535 o match-on-ipv4, match-on-ipv6, match-on-tcp, match-on-udp, match- 536 on-icmp 538 Furthermore, only "accept" or "drop" actions SHOULD be included. A 539 MUD controller MAY choose to interpret "reject" as "drop". A MUD 540 controller SHOULD ignore all other actions. This is because 541 manufacturers do not have sufficient context within a local 542 deployment to know whether reject is appropriate. That is a decision 543 that should be left to a network administrator. 545 Given that MUD does not deal with interfaces, the support of the 546 "ietf-interfaces" module [RFC7223] is not required. Specifically, 547 the support of interface-related features and branches (e.g., 548 interface-attachment and interface-stats) of the ACL YANG module is 549 not required. 551 In fact, MUD controllers MAY ignore any particular component of a 552 description or MAY ignore the description in its entirety, and SHOULD 553 carefully inspect all MUD descriptions. Publishers of MUD files MUST 554 NOT include other nodes except as described in Section 3.8. See that 555 section for more information. 557 2.1. The IETF-MUD YANG Module 559 This module is structured into three parts: 561 o The first container "mud" holds information that is relevant to 562 retrieval and validity of the MUD file itself, as well as policy 563 intended to and from the Thing. 565 o The second component augments the matching container of the ACL 566 model to add several nodes that are relevant to the MUD URL, or 567 otherwise abstracted for use within a local environment. 569 o The third component augments the tcp-acl container of the ACL 570 model to add the ability to match on the direction of initiation 571 of a TCP connection. 573 A valid MUD file will contain two root objects, a "mud" container and 574 an "access-lists" container. Extensions may add additional root 575 objects as required. As a reminder, when parsing access-lists, 576 elements within a "match" block are logically ANDed. In general, a 577 single abstraction in a match statement should be used. For 578 instance, it makes little sense to match both "my-controller" and 579 "controller" with an argument, since they are highly unlikely to be 580 the same value. 582 A simplified graphical representation of the data models is used in 583 this document. The meaning of the symbols in these diagrams is 584 explained in [I-D.ietf-netmod-yang-tree-diagrams]. 586 module: ietf-mud 587 +--rw mud! 588 +--rw mud-version uint8 589 +--rw mud-url inet:uri 590 +--rw last-update yang:date-and-time 591 +--rw mud-signature? inet:uri 592 +--rw cache-validity? uint8 593 +--rw is-supported boolean 594 +--rw systeminfo? inet:uri 595 +--rw mfg-name? string 596 +--rw model-name? string 597 +--rw firmware-rev? string 598 +--rw software-rev? string 599 +--rw extensions* string 600 +--rw from-device-policy 601 | +--rw access-lists 602 | +--rw access-list* [name] 603 | +--rw name -> /acl:access-lists/acl/name 604 +--rw to-device-policy 605 +--rw access-lists 606 +--rw access-list* [name] 607 +--rw name -> /acl:access-lists/acl/name 608 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/acl:matches: 609 +--rw mud 610 +--rw manufacturer? inet:host 611 +--rw same-manufacturer? empty 612 +--rw model? inet:uri 613 +--rw local-networks? empty 614 +--rw controller? inet:uri 615 +--rw my-controller? empty 616 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/acl: 617 matches/acl:l4/acl:tcp: 618 +--rw direction-initiated? direction 620 3. Data Node Definitions 622 Note that in this section, when we use the term "match" we are 623 referring to the ACL model "matches" node. 625 The following nodes are defined. 627 3.1. mud-version 629 This node specifies the integer version of the MUD specification. 630 This memo specifies version 1. 632 3.2. to-device-policy and from-device-policy containers 634 [I-D.ietf-netmod-acl-model] describes access-lists. In the case of 635 MUD, a MUD file must be explicit in describing the communication 636 pattern of a Thing, and that includes indicating what is to be 637 permitted or denied in either direction of communication. Hence each 638 of these containers indicates the appropriate direction of a flow in 639 association with a particular Thing. They contain references to 640 specific access-lists. 642 3.3. last-update 644 This is a date-and-time value of when the MUD file was generated. 645 This is akin to a version number. Its form is taken from [RFC6991] 646 which, for those keeping score, in turn was taken from Section 5.6 of 647 [RFC3339], which was taken from [ISO.8601.1988]. 649 3.4. cache-validity 651 This uint8 is the period of time in hours that a network management 652 station MUST wait since its last retrieval before checking for an 653 update. It is RECOMMENDED that this value be no less than 24 and 654 MUST NOT be more than 168 for any Thing that is supported. This 655 period SHOULD be no shorter than any period determined through HTTP 656 caching directives (e.g., "cache-control" or "Expires"). N.B., 657 expiring of this timer does not require the MUD controller to discard 658 the MUD file, nor terminate access to a Thing. See Section 15 for 659 more information. 661 3.5. is-supported 663 This boolean is an indication from the manufacturer to the network 664 administrator as to whether or not the Thing is supported. In this 665 context a Thing is said to not be supported if the manufacturer 666 intends never to issue an update to the Thing or never update the MUD 667 file. A MUD controller MAY still periodically check for updates. 669 3.6. systeminfo 671 This is a textual UTF-8 description of the Thing to be connected. 672 The intent is for administrators to be able to see a localized name 673 associated with the Thing. It SHOULD NOT exceed 60 characters worth 674 of display space (that is- what the administrator actually sees). 676 3.7. mfg-name, hardware-rev, software-rev, model-name firmware-rev 678 These optional fields are filled in as specified by 679 [I-D.ietf-netmod-entity]. Note that firmware-rev and software-rev 680 MUST NOT be populated in a MUD file if the device can be upgraded but 681 the MUD-URL cannot be. This would be the case, for instance, with 682 MUR-URLs that are contained in 802.1AR certificates. 684 3.8. extensions 686 This optional leaf-list names MUD extensions that are used in the MUD 687 file. Note that NO MUD extensions may be used in a MUD file without 688 the extensions being declared. Implementations MUST ignore any node 689 in this file that they do not understand. 691 Note that extensions can either extend the MUD file as described in 692 the previous paragraph, or they might reference other work. An 693 extension example can be found in Appendix C. 695 3.9. manufacturer 697 This node consists of a hostname that would be matched against the 698 authority component of another Thing's MUD URL. In its simplest form 699 "manufacturer" and "same-manufacturer" may be implemented as access- 700 lists. In more complex forms, additional network capabilities may be 701 used. For example, if one saw the line "manufacturer" : 702 "flobbidy.example.com", then all Things that registered with a MUD 703 URL that contained flobbity.example.com in its authority section 704 would match. 706 3.10. same-manufacturer 708 This null-valued node is an equivalent for when the manufacturer 709 element is used to indicate the authority that is found in another 710 Thing's MUD URL matches that of the authority found in this Thing's 711 MUD URL. For example, if the Thing's MUD URL were 712 https://b1.example.com/ThingV1, then all devices that had MUD URL 713 with an authority section of b1.example.com would match. 715 3.11. model 717 This string matches the entire MUD URL, thus covering the model that 718 is unique within the context of the authority. It may contain not 719 only model information, but versioning information as well, and any 720 other information that the manufacturer wishes to add. The intended 721 use is for devices of this precise class to match, to permit or deny 722 communication between one another. 724 3.12. local-networks 726 This null-valued node expands to include local networks. Its default 727 expansion is that packets must not traverse toward a default route 728 that is received from the router. However, administrators may expand 729 the expression as is appropriate in their deployments. 731 3.13. controller 733 This URI specifies a value that a controller will register with the 734 MUD controller. The node then is expanded to the set of hosts that 735 are so registered. This node may also be a URN. In this case, the 736 URN describes a well known service, such as DNS or NTP. 738 Great care should be used when invoking the controller class. For 739 one thing, it requires some understanding by the administrator as to 740 when it is appropriate. Classes that are standardized may make it 741 possible to easily name devices that support standard functions. For 742 instance, the MUD controller could have some knowledge of which DNS 743 servers should be used for any particular group of Things. Non- 744 standard classes will likely require some sort of administrator 745 interaction. Pre-registration in such classes by controllers with 746 the MUD server is encouraged. The mechanism to do that is beyond the 747 scope of this work. 749 Controller URIs MAY take the form of a URL (e.g. "http[s]://"). 750 However, MUD controllers MUST NOT resolve and retrieve such files, 751 and it is RECOMMENDED that there be no such file at this time, as 752 their form and function may be defined at a point in the future. For 753 now, URLs should serve simply as class names and may be populated by 754 the local deployment administrator. 756 3.14. my-controller 758 This null-valued node signals to the MUD controller to use whatever 759 mapping it has for this MUD URL to a particular group of hosts. This 760 may require prompting the administrator for class members. Future 761 work should seek to automate membership management. 763 3.15. direction-initiated 765 When applied this matches packets when the flow was initiated in the 766 corresponding direction. [RFC6092] specifies IPv6 guidance best 767 practices. While that document is scoped specifically to IPv6, its 768 contents are applicable for IPv4 as well. When this flag is set, and 769 the system has no reason to believe a flow has been initiated it MUST 770 drop the packet. This node may be implemented in its simplest form 771 by looking at naked SYN bits, but may also be implemented through 772 more stateful mechanisms. 774 4. Processing of the MUD file 776 To keep things relatively simple in addition to whatever definitions 777 exist, we also apply two additional default behaviors: 779 o Anything not explicitly permitted is denied. 781 o Local DNS and NTP are, by default, permitted to and from the 782 Thing. 784 An explicit description of the defaults can be found in Appendix B. 785 These are applied AFTER all other explicit rules. Thus, a default 786 behavior can be changed with a "drop" action. 788 5. What does a MUD URL look like? 790 MUD URLs are required to use the HTTPS scheme, in order to establish 791 the MUD file server's identity and assure integrity of the MUD file. 793 Any "https://" URL without a query component can be a MUD URL. For 794 example: 796 https://things.example.org/product_abc123/v5 797 https://www.example.net/mudfiles/temperature_sensor/ 798 https://example.com/lightbulbs/colour/v1 800 ======= The MUD URL identifies a Thing with a specificity according 801 to the manufacturer's wishes. It could include a brand name, model 802 number, or something more specific. It also could provide a means to 803 indicate what version the product is. 805 Specifically, if the intended communication patterns of a Thing 806 change, as compared to other things, the MUD URL should change. For 807 example, if a new model of light bulb is released that requires 808 access to different network services, it would have a separate MUD 809 URL from those that do not. 811 The query string of the MUD URL is reserved for potential future use; 812 MUD URLs MUST NOT contain queries when sent to the controller. MUD 813 file servers MUST ignore query parameters that they do not 814 understand. 816 Note that if the MUD URL contains a fragment identifier (e.g., 817 "#foo"), that information will not be sent to the MUD file server in 818 the HTTP request. However, it will still be considered a separate 819 MUD URL by the controller. 821 6. The MUD YANG Model 823 file "ietf-mud@2018-02-20.yang" 824 module ietf-mud { 825 yang-version 1.1; 826 namespace "urn:ietf:params:xml:ns:yang:ietf-mud"; 827 prefix ietf-mud; 829 import ietf-access-control-list { 830 prefix acl; 831 } 832 import ietf-yang-types { 833 prefix yang; 834 } 835 import ietf-inet-types { 836 prefix inet; 837 } 839 organization 840 "IETF OPSAWG (Ops Area) Working Group"; 841 contact 842 "WG Web: http://tools.ietf.org/wg/opsawg/ 843 WG List: opsawg@ietf.org 844 Author: Eliot Lear 845 lear@cisco.com 846 Author: Ralph Droms 847 rdroms@gmail.com 848 Author: Dan Romascanu 849 dromasca@gmail.com 851 "; 852 description 853 "This YANG module defines a component that augments the 854 IETF description of an access list. This specific module 855 focuses on additional filters that include local, model, 856 and same-manufacturer. 858 This module is intended to be serialized via JSON and stored 859 as a file, as described in RFC XXXX [RFC Editor to fill in with 860 this document #]. 862 Copyright (c) 2016,2017 IETF Trust and the persons 863 identified as the document authors. All rights reserved. 864 Redistribution and use in source and binary forms, with or 865 without modification, is permitted pursuant to, and subject 866 to the license terms contained in, the Simplified BSD 867 License set forth in Section 4.c of the IETF Trust's Legal 868 Provisions Relating to IETF Documents 869 (http://trustee.ietf.org/license-info). 870 This version of this YANG module is part of RFC XXXX; see 871 the RFC itself for full legal notices."; 873 revision 2018-02-20 { 874 description 875 "Initial proposed standard."; 876 reference 877 "RFC XXXX: Manufacturer Usage Description 878 Specification"; 879 } 881 typedef direction { 882 type enumeration { 883 enum "to-device" { 884 description 885 "packets or flows destined to the target 886 Thing"; 887 } 888 enum "from-device" { 889 description 890 "packets or flows destined from 891 the target Thing"; 892 } 893 } 894 description 895 "Which way are we talking about?"; 896 } 898 container mud { 899 presence "Enabled for this particular MUD URL"; 900 description 901 "MUD related information, as specified 902 by RFC-XXXX [RFC Editor to fill in]."; 903 uses mud-grouping; 904 } 906 grouping mud-grouping { 907 description 908 "Information about when support end(ed), and 909 when to refresh"; 911 leaf mud-version { 912 type uint8; 913 mandatory true; 914 description "This is the version of the MUD 915 specification. This memo specifies version 1."; 916 } 918 leaf mud-url { 919 type inet:uri; 920 mandatory true; 921 description 922 "This is the MUD URL associated with the entry found 923 in a MUD file."; 924 } 925 leaf last-update { 926 type yang:date-and-time; 927 mandatory true; 928 description 929 "This is intended to be when the current MUD file 930 was generated. MUD Controllers SHOULD NOT check 931 for updates between this time plus cache validity"; 932 } 934 leaf mud-signature { 935 type inet:uri; 936 description "A URI that resolves to a signature as 937 described in this specification."; 938 } 940 leaf cache-validity { 941 type uint8 { 942 range "1..168"; 943 } 944 units "hours"; 945 default "48"; 946 description 947 "The information retrieved from the MUD server is 948 valid for these many hours, after which it should 949 be refreshed. N.B. MUD controller implementations 950 need not discard MUD files beyond this period."; 951 } 952 leaf is-supported { 953 type boolean; 954 mandatory true; 955 description 956 "This boolean indicates whether or not the Thing is 957 currently supported by the manufacturer."; 958 } 959 leaf systeminfo { 960 type inet:uri; 961 description 962 "A URL to a description of this Thing. This 963 should be a brief localized description. The 964 reference text should be no more than octets. 965 systeminfo may be displayed to the user to 966 determine whether to allow the Thing on the 967 network."; 968 } 970 leaf mfg-name { 971 type string; 972 description "Manufacturer name, as described in 973 the ietf-hardware yang module."; 974 } 976 leaf model-name { 977 type string; 978 description "Model name, as described in the 979 ietf-hardware yang module."; 980 } 982 leaf firmware-rev { 983 type string; 984 description "firmware-rev, as described in the 985 ietf-hardware yang module. Note this field MUST 986 NOT be included when the device can be updated 987 but the MUD-URL cannot."; 988 } 990 leaf software-rev { 991 type string; 992 description "software-rev, as described in the 993 ietf-hardware yang module. Note this field MUST 994 NOT be included when the device can be updated 995 but the MUD-URL cannot."; 996 } 998 leaf-list extensions { 999 type string { 1000 length "1..40"; 1001 } 1002 description 1003 "A list of extension names that are used in this MUD 1004 file. Each name is registered with the IANA and 1005 described in an RFC."; 1006 } 1007 container from-device-policy { 1008 description 1009 "The policies that should be enforced on traffic 1010 coming from the device. These policies are not 1011 necessarily intended to be enforced at a single 1012 point, but may be rendered by the controller to any 1013 relevant enorcement points in the network or 1014 elsewhere."; 1015 uses access-lists; 1016 } 1017 container to-device-policy { 1018 description 1019 "The policies that should be enforced on traffic 1020 going to the device. These policies are not 1021 necessarily intended to be enforced at a single 1022 point, but may be rendered by the controller to any 1023 relevant enorcement points in the network or 1024 elsewhere."; 1025 uses access-lists; 1026 } 1027 } 1029 grouping access-lists { 1030 description 1031 "A grouping for access lists in the context of device 1032 policy."; 1033 container access-lists { 1034 description 1035 "The access lists that should be applied to traffic 1036 to or from the device."; 1037 list access-list { 1038 key "name"; 1039 description 1040 "Each entry on this list refers to an ACL that 1041 should be present in the overall access list 1042 data model. Each ACL is identified by name and 1043 type."; 1044 leaf name { 1045 type leafref { 1046 path "/acl:access-lists/acl:acl/acl:name"; 1047 } 1048 description 1049 "The name of the ACL for this entry."; 1050 } 1051 } 1052 } 1053 } 1054 augment "/acl:access-lists/acl:acl/acl:aces/acl:ace/acl:matches" { 1055 description 1056 "adding abstractions to avoid need of IP addresses"; 1058 container mud { 1059 description 1060 "MUD-specific matches."; 1061 leaf manufacturer { 1062 type inet:host; 1063 description 1064 "A domain that is intended to match the authority 1065 section of the MUD URL. This node is used to specify 1066 one or more manufacturers a device should 1067 be authorized to access."; 1068 } 1069 leaf same-manufacturer { 1070 type empty; 1071 description 1072 "This node matches the authority section of the MUD URL 1073 of a Thing. It is intended to grant access to all 1074 devices with the same authority section."; 1075 } 1076 leaf model { 1077 type inet:uri; 1078 description 1079 "Devices of the specified model type will match if 1080 they have an identical MUD URL."; 1081 } 1082 leaf local-networks { 1083 type empty; 1084 description 1085 "IP addresses will match this node if they are 1086 considered local addresses. A local address may be 1087 a list of locally defined prefixes and masks 1088 that indicate a particular administrative scope."; 1089 } 1090 leaf controller { 1091 type inet:uri; 1092 description 1093 "This node names a class that has associated with it 1094 zero or more IP addresses to match against. These 1095 may be scoped to a manufacturer or via a standard 1096 URN."; 1097 } 1098 leaf my-controller { 1099 type empty; 1100 description 1101 "This node matches one or more network elements that 1102 have been configured to be the controller for this 1103 Thing, based on its MUD URL."; 1104 } 1105 } 1107 } 1108 augment "/acl:access-lists/acl:acl/acl:aces/" + 1109 "acl:ace/acl:matches/acl:l4/acl:tcp" { 1110 description 1111 "Adding domain names to matching"; 1112 leaf direction-initiated { 1113 type direction; 1114 description 1115 "This node matches based on which direction a 1116 connection was initiated. The means by which that 1117 is determined is discussed in this document."; 1118 } 1119 } 1120 } 1122 1124 7. The Domain Name Extension to the ACL Model 1126 This module specifies an extension to IETF-ACL model such that domain 1127 names may be referenced by augmenting the "matches" node. Different 1128 implementations may deploy differing methods to maintain the mapping 1129 between IP address and domain name, if indeed any are needed. 1130 However, the intent is that resources that are referred to using a 1131 name should be authorized (or not) within an access list. 1133 The structure of the change is as follows: 1135 module: ietf-acldns 1136 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/acl:matches 1137 /acl:l3/acl:ipv4: 1138 +--rw src-dnsname? inet:host 1139 +--rw dst-dnsname? inet:host 1140 augment /acl:access-lists/acl:acl/acl:aces/acl:ace/acl:matches 1141 /acl:l3/acl:ipv6: 1142 +--rw src-dnsname? inet:host 1143 +--rw dst-dnsname? inet:host 1145 The choice of these particular points in the access-list model is 1146 based on the assumption that we are in some way referring to IP- 1147 related resources, as that is what the DNS returns. A domain name in 1148 our context is defined in [RFC6991]. The augmentations are 1149 replicated across IPv4 and IPv6 to allow MUD file authors the ability 1150 to control the IP version that the Thing may utilize. 1152 The following node are defined. 1154 7.1. src-dnsname 1156 The argument corresponds to a domain name of a source as specified by 1157 inet:host. A number of means may be used to resolve hosts. What is 1158 important is that such resolutions be consistent with ACLs required 1159 by Things to properly operate. 1161 7.2. dst-dnsname 1163 The argument corresponds to a domain name of a destination as 1164 specified by inet:host See the previous section relating to 1165 resolution. 1167 Note when using either of these with a MUD file, because access is 1168 associated with a particular Thing, MUD files MUST not contain either 1169 a src-dnsname in an ACL associated with from-device-policy or a dst- 1170 dnsname associated with to-device-policy. 1172 7.3. The ietf-acldns Model 1174 file "ietf-acldns@2018-02-20.yang" 1175 module ietf-acldns { 1176 yang-version 1.1; 1177 namespace "urn:ietf:params:xml:ns:yang:ietf-acldns"; 1178 prefix "ietf-acldns"; 1180 import ietf-access-control-list { 1181 prefix "acl"; 1182 } 1184 import ietf-inet-types { 1185 prefix "inet"; 1186 } 1188 organization 1189 "IETF OPSAWG (Ops Area) Working Group"; 1191 contact 1192 "WG Web: http://tools.ietf.org/wg/opsawg/ 1193 WG List: opsawg@ietf.org 1194 Author: Eliot Lear 1195 lear@cisco.com 1196 Author: Ralph Droms 1197 rdroms@gmail.com 1198 Author: Dan Romascanu 1199 dromasca@gmail.com 1200 "; 1202 description 1203 "This YANG module defines a component that augments the 1204 IETF description of an access list to allow dns names 1205 as matching criteria."; 1207 revision "2018-02-20" { 1208 description "Base version of dnsname extension of ACL model"; 1209 reference "RFC XXXX: Manufacturer Usage Description 1210 Specification"; 1211 } 1213 grouping dns-matches { 1214 description "Domain names for matching."; 1216 leaf src-dnsname { 1217 type inet:host; 1218 description "domain name to be matched against"; 1219 } 1220 leaf dst-dnsname { 1221 type inet:host; 1222 description "domain name to be matched against"; 1223 } 1224 } 1226 augment "/acl:access-lists/acl:acl/acl:aces/acl:ace/" + 1227 "acl:matches/acl:l3/acl:ipv4" { 1228 description "Adding domain names to matching"; 1229 uses dns-matches; 1230 } 1232 augment "/acl:access-lists/acl:acl/" + 1233 "acl:aces/acl:ace/" + 1234 "acl:matches/acl:l3/acl:ipv6" { 1235 description "Adding domain names to matching"; 1236 uses dns-matches; 1237 } 1238 } 1239 1241 8. MUD File Example 1243 This example contains two access lists that are intended to provide 1244 outbound access to a cloud service on TCP port 443. 1246 { 1247 "ietf-mud:mud": { 1248 "mud-version": 1, 1249 "mud-url": "https://lighting.example.com/lightbulb2000", 1250 "last-update": "2018-02-08T14:39:15+01:00", 1251 "cache-validity": 48, 1252 "is-supported": true, 1253 "systeminfo": "The BMS Example Lightbulb", 1254 "from-device-policy": { 1255 "access-lists": { 1256 "access-list": [ 1257 { 1258 "name": "mud-94934-v6fr" 1259 } 1260 ] 1261 } 1262 }, 1263 "to-device-policy": { 1264 "access-lists": { 1265 "access-list": [ 1266 { 1267 "name": "mud-94934-v6to" 1268 } 1269 ] 1270 } 1271 } 1272 }, 1273 "ietf-access-control-list:access-lists": { 1274 "acl": [ 1275 { 1276 "name": "mud-94934-v6to", 1277 "type": "ipv6-acl-type", 1278 "aces": { 1279 "ace": [ 1280 { 1281 "name": "cl0-todev", 1282 "matches": { 1283 "ipv6": { 1284 "ietf-acldns:src-dnsname": "service.bms.example.com", 1285 "protocol": 6 1286 }, 1287 "tcp": { 1288 "ietf-mud:direction-initiated": "from-device", 1289 "source-port-range-or-operator": { 1290 "operator": "eq", 1291 "port": 443 1292 } 1293 } 1294 }, 1295 "actions": { 1296 "forwarding": "accept" 1298 } 1299 } 1300 ] 1301 } 1302 }, 1303 { 1304 "name": "mud-94934-v6fr", 1305 "type": "ipv6-acl-type", 1306 "aces": { 1307 "ace": [ 1308 { 1309 "name": "cl0-frdev", 1310 "matches": { 1311 "ipv6": { 1312 "ietf-acldns:dst-dnsname": "service.bms.example.com", 1313 "protocol": 6 1314 }, 1315 "tcp": { 1316 "ietf-mud:direction-initiated": "from-device", 1317 "destination-port-range-or-operator": { 1318 "operator": "eq", 1319 "port": 443 1320 } 1321 } 1322 }, 1323 "actions": { 1324 "forwarding": "accept" 1325 } 1326 } 1327 ] 1328 } 1329 } 1330 ] 1331 } 1332 } 1334 In this example, two policies are declared, one from the Thing and 1335 the other to the Thing. Each policy names an access list that 1336 applies to the Thing, and one that applies from. Within each access 1337 list, access is permitted to packets flowing to or from the Thing 1338 that can be mapped to the domain name of "service.bms.example.com". 1339 For each access list, the enforcement point should expect that the 1340 Thing initiated the connection. 1342 9. The MUD URL DHCP Option 1344 The IPv4 MUD URL client option has the following format: 1346 +------+-----+------------------------------ 1347 | code | len | MUD URL 1348 +------+-----+------------------------------ 1350 Code OPTION_MUD_URL_V4 (161) is assigned by IANA. len is a single 1351 octet that indicates the length of the URL in octets. MUD URL is a 1352 URL. MUD URLs MUST NOT exceed 255 octets. 1354 The IPv6 MUD URL client option has the following format: 1356 0 1 2 3 1357 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 1358 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1359 | OPTION_MUD_URL_V6 | option-length | 1360 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1361 | MUD URL | 1362 | ... | 1363 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1365 OPTION_MUD_URL_V6 (112; assigned by IANA). 1367 option-length contains the length of the URL in octets. 1369 The intent of this option is to provide both a new Thing classifier 1370 to the network as well as some recommended configuration to the 1371 routers that implement policy. However, it is entirely the purview 1372 of the network system as managed by the network administrator to 1373 decide what to do with this information. The key function of this 1374 option is simply to identify the type of Thing to the network in a 1375 structured way such that the policy can be easily found with existing 1376 toolsets. 1378 9.1. Client Behavior 1380 A DHCPv4 client MAY emit a DHCPv4 option and a DHCPv6 client MAY emit 1381 DHCPv6 option. These options are singletons, as specified in 1382 [RFC7227]. Because clients are intended to have at most one MUD URL 1383 associated with them, they may emit at most one MUD URL option via 1384 DHCPv4 and one MUD URL option via DHCPv6. In the case where both v4 1385 and v6 DHCP options are emitted, the same URL MUST be used. 1387 Clients SHOULD log or otherwise report improper acknowledgments from 1388 servers, but they MUST NOT modify their MUD URL configuration based 1389 on a server's response. The server's response is only an 1390 acknowledgment that the server has processed the option, and promises 1391 no specific network behavior to the client. In particular, it may 1392 not be possible for the server to retrieve the file associated with 1393 the MUD URL, or the local network administration may not wish to use 1394 the usage description. Neither of these situations should be 1395 considered in any way exceptional. 1397 9.2. Server Behavior 1399 A DHCP server may ignore these options or take action based on 1400 receipt of these options. If a server successfully parses the option 1401 and the URL, it MUST return the option with length field set to zero 1402 and a corresponding null URL field as an acknowledgment. Even in 1403 this circumstance, no specific network behavior is guaranteed. When 1404 a server consumes this option, it will either forward the URL and 1405 relevant client information (such as the gateway address or giaddr) 1406 to a network management system, or it will retrieve the usage 1407 description itself by resolving the URL. 1409 DHCP servers may implement MUD functionality themselves or they may 1410 pass along appropriate information to a network management system or 1411 MUD controller. A DHCP server that does process the MUD URL MUST 1412 adhere to the process specified in [RFC2818] and [RFC5280] to 1413 validate the TLS certificate of the web server hosting the MUD file. 1414 Those servers will retrieve the file, process it, create and install 1415 the necessary configuration on the relevant network element. Servers 1416 SHOULD monitor the gateway for state changes on a given interface. A 1417 DHCP server that does not provide MUD functionality and has forwarded 1418 a MUD URL to a MUD controller MUST notify the MUD controller of any 1419 corresponding change to the DHCP state of the client (such as 1420 expiration or explicit release of a network address lease). 1422 9.3. Relay Requirements 1424 There are no additional requirements for relays. 1426 10. The Manufacturer Usage Description (MUD) URL X.509 Extension 1428 This section defines an X.509 non-critical certificate extension that 1429 contains a single Uniform Resource Locator (URL) that points to an 1430 on-line Manufacturer Usage Description concerning the certificate 1431 subject. URI must be represented as described in Section 7.4 of 1432 [RFC5280]. 1434 Any Internationalized Resource Identifiers (IRIs) MUST be mapped to 1435 URIs as specified in Section 3.1 of [RFC3987] before they are placed 1436 in the certificate extension. 1438 The semantics of the URL are defined Section 5 of this document. 1440 The choice of id-pe is based on guidance found in Section 4.2.2 of 1441 [RFC5280]: 1443 These extensions may be used to direct applications to on-line 1444 information about the issuer or the subject. 1446 The MUD URL is precisely that: online information about the 1447 particular subject. 1449 The new extension is identified as follows: 1451 1453 MUDURLExtnModule-2016 { iso(1) identified-organization(3) dod(6) 1454 internet(1) security(5) mechanisms(5) pkix(7) 1455 id-mod(0) id-mod-mudURLExtn2016(88) } 1457 DEFINITIONS IMPLICIT TAGS ::= BEGIN 1459 -- EXPORTS ALL -- 1461 IMPORTS 1462 EXTENSION 1463 FROM PKIX-CommonTypes-2009 1464 { iso(1) identified-organization(3) dod(6) internet(1) 1465 security(5) mechanisms(5) pkix(7) id-mod(0) 1466 id-mod-pkixCommon-02(57) } 1468 id-pe 1469 FROM PKIX1Explicit-2009 1470 { iso(1) identified-organization(3) dod(6) internet(1) 1471 security(5) mechanisms(5) pkix(7) id-mod(0) 1472 id-mod-pkix1-explicit-02(51) } ; 1473 MUDCertExtensions EXTENSION ::= { ext-MUDURL, ... } 1474 ext-MUDURL EXTENSION ::= { SYNTAX MUDURLSyntax 1475 IDENTIFIED BY id-pe-mud-url } 1477 id-pe-mud-url OBJECT IDENTIFIER ::= { id-pe 25 } 1479 MUDURLSyntax ::= IA5String 1481 END 1483 1485 While this extension can appear in either an 802.AR manufacturer 1486 certificate (IDevID) or deployment certificate (LDevID), of course it 1487 is not guaranteed in either, nor is it guaranteed to be carried over. 1488 It is RECOMMENDED that MUD controller implementations maintain a 1489 table that maps a Thing to its MUD URL based on IDevIDs. 1491 11. The Manufacturer Usage Description LLDP extension 1493 The IEEE802.1AB Link Layer Discovery Protocol (LLDP) is a one hop 1494 vendor-neutral link layer protocol used by end hosts network Things 1495 for advertising their identity, capabilities, and neighbors on an 1496 IEEE 802 local area network. Its Type-Length-Value (TLV) design 1497 allows for 'vendor-specific' extensions to be defined. IANA has a 1498 registered IEEE 802 organizationally unique identifier (OUI) defined 1499 as documented in [RFC7042]. The MUD LLDP extension uses a subtype 1500 defined in this document to carry the MUD URL. 1502 The LLDP vendor specific frame has the following format: 1504 +--------+--------+----------+---------+-------------- 1505 |TLV Type| len | OUI |subtype | MUD URL 1506 | =127 | |= 00 00 5E| = 1 | 1507 |(7 bits)|(9 bits)|(3 octets)|(1 octet)|(1-255 octets) 1508 +--------+--------+----------+---------+-------------- 1510 where: 1512 o TLV Type = 127 indicates a vendor-specific TLV 1514 o len - indicates the TLV string length 1516 o OUI = 00 00 5E is the organizationally unique identifier of IANA 1518 o subtype = 1 (to be assigned by IANA for the MUD URL) 1520 o MUD URL - the length MUST NOT exceed 255 octets 1522 The intent of this extension is to provide both a new Thing 1523 classifier to the network as well as some recommended configuration 1524 to the routers that implement policy. However, it is entirely the 1525 purview of the network system as managed by the network administrator 1526 to decide what to do with this information. The key function of this 1527 extension is simply to identify the type of Thing to the network in a 1528 structured way such that the policy can be easily found with existing 1529 toolsets. 1531 Hosts, routers, or other network elements that implement this option 1532 are intended to have at most one MUD URL associated with them, so 1533 they may transmit at most one MUD URL value. 1535 Hosts, routers, or other network elements that implement this option 1536 may ignore these options or take action based on receipt of these 1537 options. For example they may fill in information in the respective 1538 extensions of the LLDP Management Information Base (LLDP MIB). LLDP 1539 operates in a one-way direction. LLDPDUs are not exchanged as 1540 information requests by one Thing and response sent by another Thing. 1541 The other Things do not acknowledge LLDP information received from a 1542 Thing. No specific network behavior is guaranteed. When a Thing 1543 consumes this extension, it may either forward the URL and relevant 1544 remote Thing information to a MUD controller, or it will retrieve the 1545 usage description by resolving the URL in accordance with normal HTTP 1546 semantics. 1548 12. Creating and Processing of Signed MUD Files 1550 Because MUD files contain information that may be used to configure 1551 network access lists, they are sensitive. To insure that they have 1552 not been tampered with, it is important that they be signed. We make 1553 use of DER-encoded Cryptographic Message Syntax (CMS) [RFC5652] for 1554 this purpose. 1556 12.1. Creating a MUD file signature 1558 A MUD file MUST be signed using CMS as an opaque binary object. In 1559 order to make successful verification more likely, intermediate 1560 certificates SHOULD be included. The signature is stored at the 1561 location specified in the MUD file. Signatures are transferred using 1562 content-type "application/pkcs7-signature". 1564 For example: 1566 % openssl cms -sign -signer mancertfile -inkey mankey \ 1567 -in mudfile -binary -outform DER - \ 1568 -certfile intermediatecert -out mudfile.p7s 1570 Note: A MUD file may need to be re-signed if the signature expires. 1572 12.2. Verifying a MUD file signature 1574 Prior to retrieving a MUD file the MUD controller SHOULD retrieve the 1575 MUD signature file by retrieving the value of "mud-signature" and 1576 validating the signature across the MUD file. 1578 Upon retrieving a MUD file, a MUD controller MUST validate the 1579 signature of the file before continuing with further processing. A 1580 MUD controller MUST cease processing of that file it cannot validate 1581 the chain of trust to a known trust anchor until an administrator has 1582 given approval. 1584 The purpose of the signature on the file is to assign accountability 1585 to an entity, whose reputation can be used to guide administrators on 1586 whether or not to accept a given MUD file. It is already common 1587 place to check web reputation on the location of a server on which a 1588 file resides. While it is likely that the manufacturer will be the 1589 signer of the file, this is not strictly necessary, and may not be 1590 desirable. For one thing, in some environments, integrators may 1591 install their own certificates. For another, what is more important 1592 is the accountability of the recommendation, and not the 1593 cryptographic relationship between the device and the file. 1595 An example: 1597 % openssl cms -verify -in mudfile.p7s -inform DER -content mudfile 1599 Note the additional step of verifying the common trust root. 1601 13. Extensibility 1603 One of our design goals is to see that MUD files are able to be 1604 understood by as broad a cross-section of systems as is possible. 1605 Coupled with the fact that we have also chosen to leverage existing 1606 mechanisms, we are left with no ability to negotiate extensions and a 1607 limited desire for those extensions in any event. A such, a two-tier 1608 extensibility framework is employed, as follows: 1610 1. At a coarse grain, a protocol version is included in a MUD URL. 1611 This memo specifies MUD version 1. Any and all changes are 1612 entertained when this version is bumped. Transition approaches 1613 between versions would be a matter for discussion in future 1614 versions. 1616 2. At a finer grain, only extensions that would not incur additional 1617 risk to the Thing are permitted. Specifically, adding nodes to 1618 the mud container is permitted with the understanding that such 1619 additions will be ignored by unaware implementations. Any such 1620 extensions SHALL be standardized through the IETF process, and 1621 MUST be named in the "extensions" list. MUD controllers MUST 1622 ignore YANG nodes they do not understand and SHOULD create an 1623 exception to be resolved by an administrator, so as to avoid any 1624 policy inconsistencies. 1626 14. Deployment Considerations 1628 Because MUD consists of a number of architectural building blocks, it 1629 is possible to assemble different deployment scenarios. One key 1630 aspect is where to place policy enforcement. In order to protect the 1631 Thing from other Things within a local deployment, policy can be 1632 enforced on the nearest switch or access point. In order to limit 1633 unwanted traffic within a network, it may also be advisable to 1634 enforce policy as close to the Internet as possible. In some 1635 circumstances, policy enforcement may not be available at the closest 1636 hop. At that point, the risk of so-called east-west infection is 1637 increased to the number of Things that are able to communicate 1638 without protection. 1640 A caution about some of the classes: admission of a Thing into the 1641 "manufacturer" and "same-manufacturer" class may have impact on 1642 access of other Things. Put another way, the admission may grow the 1643 access-list on switches connected to other Things, depending on how 1644 access is managed. Some care should be given on managing that 1645 access-list growth. Alternative methods such as additional network 1646 segmentation can be used to keep that growth within reason. 1648 Because as of this writing MUD is a new concept, one can expect a 1649 great many devices to not have implemented it. It remains a local 1650 deployment decision as to whether a device that is first connected 1651 should be alloewed broad or limited access. Furthermore, as 1652 mentioned in the introduction, a deployment may choose to ignore a 1653 MUD policy in its entirety, but simply taken into account the MUD URL 1654 as a classifier to be used as part of a local policy decision. 1656 15. Security Considerations 1658 Based on how a MUD URL is emitted, a Thing may be able to lie about 1659 what it is, thus gaining additional network access. There are 1660 several means to limit risk in this case. The most obvious is to 1661 only believe Things that make use of certificate-based authentication 1662 such as IEEE 802.1AR certificates. When those certificates are not 1663 present, Things claiming to be of a certain manufacturer SHOULD NOT 1664 be included in that manufacturer grouping without additional 1665 validation of some form. This will occur when it makes use of 1666 primitives such as "manufacturer" for the purpose of accessing Things 1667 of a particular type. Similarly, network management systems may be 1668 able to fingerprint the Thing. In such cases, the MUD URL can act as 1669 a classifier that can be proven or disproven. Fingerprinting may 1670 have other advantages as well: when 802.1AR certificates are used, 1671 because they themselves cannot change, fingerprinting offers the 1672 opportunity to add artificats to the MUD URL. The meaning of such 1673 artifacts is left as future work. 1675 Network management systems SHOULD NOT accept a usage description for 1676 a Thing with the same MAC address that has indicated a change of 1677 authority without some additional validation (such as review by a 1678 network administrator). New Things that present some form of 1679 unauthenticated MUD URL SHOULD be validated by some external means 1680 when they would be otherwise be given increased network access. 1682 It may be possible for a rogue manufacturer to inappropriately 1683 exercise the MUD file parser, in order to exploit a vulnerability. 1684 There are three recommended approaches to address this threat. The 1685 first is to validate the signature of the MUD file. The second is to 1686 have a system do a primary scan of the file to ensure that it is both 1687 parseable and believable at some level. MUD files will likely be 1688 relatively small, to start with. The number of ACEs used by any 1689 given Thing should be relatively small as well. It may also be 1690 useful to limit retrieval of MUD URLs to only those sites that are 1691 known to have decent web or domain reputations. 1693 Use of a URL necessitates the use of domain names. If a domain name 1694 changes ownership, the new owner of that domain may be able to 1695 provide MUD files that MUD controllers would consider valid. There 1696 are a few approaches that can mitigate this attack. First, MUD 1697 controllers SHOULD cache certificates used by the MUD file server. 1698 When a new certificate is retrieved for whatever reason, the MUD 1699 controller should check to see if ownership of the domain has 1700 changed. A fair programmatic approximation of this is when the name 1701 servers for the domain have changed. If the actual MUD file has 1702 changed, the controller MAY check the WHOIS database to see if 1703 registration ownership of a domain has changed. If a change has 1704 occured, or if for some reason it is not possible to determine 1705 whether ownership has changed, further review may be warranted. 1706 Note, this remediation does not take into account the case of a Thing 1707 that was produced long ago and only recently fielded, or the case 1708 where a new MUD controller has been installed. 1710 It may not be possible for a MUD controller to retrieve a MUD file at 1711 any given time. Should a MUD controller fail to retrieve a MUD file, 1712 it SHOULD consider the existing one safe to use, at least for a time. 1713 After some period, it SHOULD log that it has been unable to retrieve 1714 the file. There may be very good reasons for such failures, 1715 including the possibility that the MUD controller is in an off-line 1716 environment, the local Internet connection has failed, or the remote 1717 Internet connection has failed. It is also possible that an attacker 1718 is attempting to prevent onboarding of a device. It is a local 1719 deployment decision as to whether or not devices may be onboarded in 1720 the face of such failures. 1722 The release of a MUD URL by a Thing reveals what the Thing is, and 1723 provides an attacker with guidance on what vulnerabilities may be 1724 present. 1726 While the MUD URL itself is not intended to be unique to a specific 1727 Thing, the release of the URL may aid an observer in identifying 1728 individuals when combined with other information. This is a privacy 1729 consideration. 1731 In addressing both of these concerns, implementors should take into 1732 account what other information they are advertising through 1733 mechanisms such as mDNS[RFC6872], how a Thing might otherwise be 1734 identified, perhaps through how it behaves when it is connected to 1735 the network, whether a Thing is intended to be used by individuals or 1736 carry personal identifying information, and then apply appropriate 1737 data minimization techniques. One approach is to make use of TEAP 1738 [RFC7170] as the means to share information with authorized 1739 components in the network. Network elements may also assist in 1740 limiting access to the MUD URL through the use of mechanisms such as 1741 DHCPv6-Shield [RFC7610]. 1743 Please note that the security considerations mentioned in Section 4.7 1744 of [I-D.ietf-netmod-rfc6087bis] are not applicable in this case 1745 because the YANG serialization is not intended to be accessed via 1746 NETCONF. However, for those who try to instantiate this model in a 1747 network element via NETCONF, all objects in each model in this draft 1748 exhibit similar security characteristics as 1749 [I-D.ietf-netmod-acl-model]. The basic purpose of MUD is to 1750 configure access, and so by its very nature can be disruptive if used 1751 by unauthorized parties. 1753 16. IANA Considerations 1755 16.1. YANG Module Registrations 1757 The following YANG modules are requested to be registred in the "IANA 1758 Module Names" registry: 1760 The ietf-mud module: 1762 o Name: ietf-mud 1764 o XML Namespace: urn:ietf:params:xml:ns:yang:ietf-mud 1766 o Prefix: ief-mud 1768 o Reference: This memo 1770 The ietf-acldns module: 1772 o Name: ietf-acldns 1774 o XML Namespace: urn:ietf:params:xml:ns:yang:ietf-acldns 1776 o Prefix: ietf-acldns 1778 o Reference: This memo 1780 16.2. DHCPv4 and DHCPv6 Options 1782 The IANA has allocated option 161 in the Dynamic Host Configuration 1783 Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry 1784 for the MUD DHCPv4 option, and option 112 for DHCPv6, as described in 1785 Section 9. 1787 16.3. PKIX Extensions 1789 IANA is kindly requested to make the following assignments for: 1791 o The MUDURLExtnModule-2016 ASN.1 module in the "SMI Security for 1792 PKIX Module Identifier" registry (1.3.6.1.5.5.7.0). 1794 o id-pe-mud-url object identifier from the "SMI Security for PKIX 1795 Certificate Extension" registry (1.3.6.1.5.5.7.1). 1797 The use of these values is specified in Section 10. 1799 16.4. MIME Media-type Registration for MUD files 1801 The following media-type is defined for transfer of MUD file: 1803 o Type name: application 1804 o Subtype name: mud+json 1805 o Required parameters: n/a 1806 o Optional parameters: n/a 1807 o Encoding considerations: 8bit; application/mud+json values 1808 are represented as a JSON object; UTF-8 encoding SHOULD be 1809 employed. 1810 o Security considerations: See Security Considerations 1811 of this document. 1812 o Interoperability considerations: n/a 1813 o Published specification: this document 1814 o Applications that use this media type: MUD controllers as 1815 specified by this document. 1816 o Fragment identifier considerations: n/a 1817 o Additional information: 1819 Magic number(s): n/a 1820 File extension(s): n/a 1821 Macintosh file type code(s): n/a 1823 o Person & email address to contact for further information: 1824 Eliot Lear , Ralph Droms 1825 o Intended usage: COMMON 1826 o Restrictions on usage: none 1827 o Author: 1828 Eliot Lear 1829 Ralph Droms 1830 o Change controller: IESG 1831 o Provisional registration? (standards tree only): No. 1833 16.5. LLDP IANA TLV Subtype Registry 1835 IANA is requested to create a new registry for IANA Link Layer 1836 Discovery Protocol (LLDP) TLV subtype values. The recommended policy 1837 for this registry is Expert Review. The maximum number of entries in 1838 the registry is 256. 1840 IANA is required to populate the initial registry with the value: 1842 LLDP subtype value = 1 (All the other 255 values should be initially 1843 marked as 'Unassigned'.) 1845 Description = the Manufacturer Usage Description (MUD) Uniform 1846 Resource Locator (URL) 1848 Reference = < this document > 1850 16.6. The MUD Well Known Universal Resource Name (URNs) 1852 The following parameter registry is requested to be added in 1853 accordance with [RFC3553] 1855 Registry name: "urn:ietf:params:mud" is requested. 1856 Specification: this document 1857 Repository: this document 1858 Index value: Encoded identically to a TCP/UDP port service 1859 name, as specified in Section 5.1 of [RFC6335] 1861 The following entries should be added to the "urn:ietf:params:mud" 1862 name space: 1864 "urn:ietf:params:mud:dns" refers to the service specified by 1865 [RFC1123]. "urn:ietf:params:mud:ntp" refers to the service specified 1866 by [RFC5905]. 1868 16.7. Extensions Registry 1870 The IANA is requested to establish a registry of extensions as 1871 follows: 1873 Registry name: MUD extensions registry 1874 Registry policy: Standards action 1875 Standard reference: document 1876 Extension name: UTF-8 encoded string, not to exceed 40 characters. 1878 Each extension MUST follow the rules specified in this specification. 1879 As is usual, the IANA issues early allocations based in accordance 1880 with [RFC7120]. 1882 17. Acknowledgments 1884 The authors would like to thank Einar Nilsen-Nygaard, who 1885 singlehandedly updated the model to match the updated ACL model, 1886 Bernie Volz, Tom Gindin, Brian Weis, Sandeep Kumar, Thorsten Dahm, 1887 John Bashinski, Steve Rich, Jim Bieda, Dan Wing, Joe Clarke, Henk 1888 Birkholz, Adam Montville, and Robert Sparks for their valuable advice 1889 and reviews. Russ Housley entirely rewrote Section 10 to be a 1890 complete module. Adrian Farrel provided the basis for privacy 1891 considerations text. Kent Watsen provided a thorough review of the 1892 architecture and the YANG model. The remaining errors in this work 1893 are entirely the responsibility of the authors. 1895 18. References 1897 18.1. Normative References 1899 [I-D.ietf-netmod-acl-model] 1900 Jethanandani, M., Huang, L., Agarwal, S., and D. Blair, 1901 "Network Access Control List (ACL) YANG Data Model", 1902 draft-ietf-netmod-acl-model-16 (work in progress), 1903 February 2018. 1905 [I-D.ietf-netmod-entity] 1906 Bierman, A., Bjorklund, M., Dong, J., and D. Romascanu, "A 1907 YANG Data Model for Hardware Management", draft-ietf- 1908 netmod-entity-08 (work in progress), January 2018. 1910 [I-D.ietf-netmod-yang-tree-diagrams] 1911 Bjorklund, M. and L. Berger, "YANG Tree Diagrams", draft- 1912 ietf-netmod-yang-tree-diagrams-06 (work in progress), 1913 February 2018. 1915 [IEEE8021AB] 1916 Institute for Electrical and Electronics Engineers, "IEEE 1917 Standard for Local and Metropolitan Area Networks-- 1918 Station and Media Access Control Connectivity Discovery", 1919 n.d.. 1921 [RFC1123] Braden, R., Ed., "Requirements for Internet Hosts - 1922 Application and Support", STD 3, RFC 1123, 1923 DOI 10.17487/RFC1123, October 1989, 1924 . 1926 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1927 Requirement Levels", BCP 14, RFC 2119, 1928 DOI 10.17487/RFC2119, March 1997, 1929 . 1931 [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", 1932 RFC 2131, DOI 10.17487/RFC2131, March 1997, 1933 . 1935 [RFC2618] Aboba, B. and G. Zorn, "RADIUS Authentication Client MIB", 1936 RFC 2618, DOI 10.17487/RFC2618, June 1999, 1937 . 1939 [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, 1940 DOI 10.17487/RFC2818, May 2000, 1941 . 1943 [RFC3315] Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, 1944 C., and M. Carney, "Dynamic Host Configuration Protocol 1945 for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 1946 2003, . 1948 [RFC3748] Aboba, B., Blunk, L., Vollbrecht, J., Carlson, J., and H. 1949 Levkowetz, Ed., "Extensible Authentication Protocol 1950 (EAP)", RFC 3748, DOI 10.17487/RFC3748, June 2004, 1951 . 1953 [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform 1954 Resource Identifier (URI): Generic Syntax", STD 66, 1955 RFC 3986, DOI 10.17487/RFC3986, January 2005, 1956 . 1958 [RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource 1959 Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987, 1960 January 2005, . 1962 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 1963 Housley, R., and W. Polk, "Internet X.509 Public Key 1964 Infrastructure Certificate and Certificate Revocation List 1965 (CRL) Profile", RFC 5280, DOI 10.17487/RFC5280, May 2008, 1966 . 1968 [RFC5652] Housley, R., "Cryptographic Message Syntax (CMS)", STD 70, 1969 RFC 5652, DOI 10.17487/RFC5652, September 2009, 1970 . 1972 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 1973 "Network Time Protocol Version 4: Protocol and Algorithms 1974 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 1975 . 1977 [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. 1978 Cheshire, "Internet Assigned Numbers Authority (IANA) 1979 Procedures for the Management of the Service Name and 1980 Transport Protocol Port Number Registry", BCP 165, 1981 RFC 6335, DOI 10.17487/RFC6335, August 2011, 1982 . 1984 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", 1985 RFC 6991, DOI 10.17487/RFC6991, July 2013, 1986 . 1988 [RFC7120] Cotton, M., "Early IANA Allocation of Standards Track Code 1989 Points", BCP 100, RFC 7120, DOI 10.17487/RFC7120, January 1990 2014, . 1992 [RFC7227] Hankins, D., Mrugalski, T., Siodelski, M., Jiang, S., and 1993 S. Krishnan, "Guidelines for Creating New DHCPv6 Options", 1994 BCP 187, RFC 7227, DOI 10.17487/RFC7227, May 2014, 1995 . 1997 [RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 1998 Protocol (HTTP/1.1): Message Syntax and Routing", 1999 RFC 7230, DOI 10.17487/RFC7230, June 2014, 2000 . 2002 [RFC7231] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer 2003 Protocol (HTTP/1.1): Semantics and Content", RFC 7231, 2004 DOI 10.17487/RFC7231, June 2014, 2005 . 2007 [RFC7610] Gont, F., Liu, W., and G. Van de Velde, "DHCPv6-Shield: 2008 Protecting against Rogue DHCPv6 Servers", BCP 199, 2009 RFC 7610, DOI 10.17487/RFC7610, August 2015, 2010 . 2012 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 2013 RFC 7950, DOI 10.17487/RFC7950, August 2016, 2014 . 2016 [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG", 2017 RFC 7951, DOI 10.17487/RFC7951, August 2016, 2018 . 2020 18.2. Informative References 2022 [FW95] Chapman, D. and E. Zwicky, "Building Internet Firewalls", 2023 January 1995. 2025 [I-D.ietf-netmod-rfc6087bis] 2026 Bierman, A., "Guidelines for Authors and Reviewers of YANG 2027 Data Model Documents", draft-ietf-netmod-rfc6087bis-17 2028 (work in progress), February 2018. 2030 [IEEE8021AR] 2031 Institute for Electrical and Electronics Engineers, 2032 "Secure Device Identity", 1998. 2034 [ISO.8601.1988] 2035 International Organization for Standardization, "Data 2036 elements and interchange formats - Information interchange 2037 - Representation of dates and times", ISO Standard 8601, 2038 June 1988. 2040 [RFC1984] IAB and IESG, "IAB and IESG Statement on Cryptographic 2041 Technology and the Internet", BCP 200, RFC 1984, 2042 DOI 10.17487/RFC1984, August 1996, 2043 . 2045 [RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet: 2046 Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002, 2047 . 2049 [RFC3553] Mealling, M., Masinter, L., Hardie, T., and G. Klyne, "An 2050 IETF URN Sub-namespace for Registered Protocol 2051 Parameters", BCP 73, RFC 3553, DOI 10.17487/RFC3553, June 2052 2003, . 2054 [RFC6092] Woodyatt, J., Ed., "Recommended Simple Security 2055 Capabilities in Customer Premises Equipment (CPE) for 2056 Providing Residential IPv6 Internet Service", RFC 6092, 2057 DOI 10.17487/RFC6092, January 2011, 2058 . 2060 [RFC6872] Gurbani, V., Ed., Burger, E., Ed., Anjali, T., Abdelnur, 2061 H., and O. Festor, "The Common Log Format (CLF) for the 2062 Session Initiation Protocol (SIP): Framework and 2063 Information Model", RFC 6872, DOI 10.17487/RFC6872, 2064 February 2013, . 2066 [RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and 2067 IETF Protocol and Documentation Usage for IEEE 802 2068 Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042, 2069 October 2013, . 2071 [RFC7170] Zhou, H., Cam-Winget, N., Salowey, J., and S. Hanna, 2072 "Tunnel Extensible Authentication Protocol (TEAP) Version 2073 1", RFC 7170, DOI 10.17487/RFC7170, May 2014, 2074 . 2076 [RFC7223] Bjorklund, M., "A YANG Data Model for Interface 2077 Management", RFC 7223, DOI 10.17487/RFC7223, May 2014, 2078 . 2080 [RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained 2081 Application Protocol (CoAP)", RFC 7252, 2082 DOI 10.17487/RFC7252, June 2014, 2083 . 2085 [RFC7452] Tschofenig, H., Arkko, J., Thaler, D., and D. McPherson, 2086 "Architectural Considerations in Smart Object Networking", 2087 RFC 7452, DOI 10.17487/RFC7452, March 2015, 2088 . 2090 [RFC7488] Boucadair, M., Penno, R., Wing, D., Patil, P., and T. 2091 Reddy, "Port Control Protocol (PCP) Server Selection", 2092 RFC 7488, DOI 10.17487/RFC7488, March 2015, 2093 . 2095 Appendix A. Changes from Earlier Versions 2097 RFC Editor to remove this section prior to publication. 2099 Draft -16 2101 o add mud-signature element based on review comments 2103 o redo mud-url 2105 o make clear that systeminfo uses UTF8 2107 Draft -13 to -14: 2109 o Final WGLC comments and review comments 2111 o Move version from MUD-URL to Model 2113 o Have MUD-URL in model 2115 o Update based on update to draft-ietf-netmod-acl-model 2117 o Point to tree diagram draft instead of 6087bis. 2119 Draft -12 to -13: 2121 o Additional WGLC comments 2123 Draft -10 to -12: 2125 These are based on WGLC comments: 2127 o Correct examples based on ACL model changes. 2129 o Change ordering nodes. 2131 o Additional explanatory text around systeminfo. 2133 o Change ordering in examples. 2135 o Make it VERY VERY VERY VERY clear that these are recommendations, 2136 not mandates. 2138 o DHCP -> NTP in some of the intro text. 2140 o Remove masa-server 2142 o "Things" to "network elements" in a few key places. 2144 o Reference to JSON YANG RFC added. 2146 Draft -10 to -11: 2148 o Example corrections 2150 o Typo 2152 o Fix two lists. 2154 o Addition of 'any-acl' and 'mud-acl' in the list of allowed 2155 features. 2157 o Clarification of what should be in a MUD file. 2159 Draft -09 to -10: 2161 o AD input. 2163 o Correct dates. 2165 o Add compliance sentence as to which ACL module features are 2166 implemented. 2168 Draft -08 to -09: 2170 o Resolution of Security Area review, IoT directorate review, GenART 2171 review, YANG doctors review. 2173 o change of YANG structure to address mandatory nodes. 2175 o Terminology cleanup. 2177 o specify out extra portion of MUD-URL. 2179 o consistency changes. 2181 o improved YANG descriptions. 2183 o Remove extra revisions. 2185 o Track ACL model changes. 2187 o Additional cautions on use of ACL model; further clarifications on 2188 extensions. 2190 Draft -07 to -08: 2192 o a number of editorials corrected. 2194 o definition of MUD file tweaked. 2196 Draft -06 to -07: 2198 o Examples updated. 2200 o Additional clarification for direction-initiated. 2202 o Additional implementation guidance given. 2204 Draft -06 to -07: 2206 o Update models to match new ACL model 2208 o extract directionality from the ACL, introducing a new device 2209 container. 2211 Draft -05 to -06: 2213 o Make clear that this is a component architecture (Polk and Watson) 2215 o Add order of operations (Watson) 2217 o Add extensions leaf-list (Pritikin) 2219 o Remove previous-mud-file (Watson) 2221 o Modify text in last-update (Watson) 2223 o Clarify local networks (Weis, Watson) 2225 o Fix contact info (Watson) 2227 o Terminology clarification (Weis) 2228 o Advice on how to handle LDevIDs (Watson) 2230 o Add deployment considerations (Watson) 2232 o Add some additional text about fingerprinting (Watson) 2234 o Appropriate references to 6087bis (Watson) 2236 o Change systeminfo to a URL to be referenced (Lear) 2238 Draft -04 to -05: * syntax error correction 2240 Draft -03 to -04: * Re-add my-controller 2242 Draft -02 to -03: * Additional IANA updates * Format correction in 2243 YANG. * Add reference to TEAP. 2245 Draft -01 to -02: * Update IANA considerations * Accept Russ Housley 2246 rewrite of X.509 text * Include privacy considerations text * Redo 2247 the URL limit. Still 255 bytes, but now stated in the URL 2248 definition. * Change URI registration to be under urn:ietf:params 2250 Draft -00 to -01: * Fix cert trust text. * change supportInformation 2251 to meta-info * Add an informational element in. * add urn registry 2252 and create first entry * add default elements 2254 Appendix B. Default MUD nodes 2256 What follows is the portion of a MUD file that permits DNS traffic to 2257 a controller that is registered with the URN 2258 "urn:ietf:params:mud:dns" and traffic NTP to a controller that is 2259 registered "urn:ietf:params:mud:ntp". This is considered the default 2260 behavior and the ACEs are in effect appended to whatever other "ace" 2261 entries that a MUD file contains. To block DNS or NTP one repeats 2262 the matching statement but replaces the "forwarding" action "accept" 2263 with "drop". Because ACEs are processed in the order they are 2264 received, the defaults would not be reached. A MUD controller might 2265 further decide to optimize to simply not include the defaults when 2266 they are overriden. 2268 Four "acl" list entries that implement default MUD nodes are listed 2269 below. Two are for IPv4 and two are for IPv6 (one in each direction 2270 for both versions of IP). Note that neither access-list name nor ace 2271 name need be retained or used in any way by local implementations, 2272 but are simply there for completeness' sake. 2274 "ietf-access-control-list:access-lists": { 2275 "acl": [ 2276 { 2277 "name": "mud-59776-v4to", 2278 "type": "ipv4-acl-type", 2279 "aces": { 2280 "ace": [ 2281 { 2282 "name": "ent0-todev", 2283 "matches": { 2284 "ietf-mud:mud": { 2285 "controller": "urn:ietf:params:mud:dns" 2286 }, 2287 "ipv4": { 2288 "protocol": 17 2289 }, 2290 "udp": { 2291 "source-port-range-or-operator": { 2292 "operator": "eq", 2293 "port": 53 2294 } 2295 } 2296 }, 2297 "actions": { 2298 "forwarding": "accept" 2299 } 2300 }, 2301 { 2302 "name": "ent1-todev", 2303 "matches": { 2304 "ietf-mud:mud": { 2305 "controller": "urn:ietf:params:mud:ntp" 2306 }, 2307 "ipv4": { 2308 "protocol": 17 2309 }, 2310 "udp": { 2311 "source-port-range-or-operator": { 2312 "operator": "eq", 2313 "port": 123 2314 } 2315 } 2316 }, 2317 "actions": { 2318 "forwarding": "accept" 2319 } 2320 } 2321 ] 2322 } 2323 }, 2324 { 2325 "name": "mud-59776-v4fr", 2326 "type": "ipv4-acl-type", 2327 "aces": { 2328 "ace": [ 2329 { 2330 "name": "ent0-frdev", 2331 "matches": { 2332 "ietf-mud:mud": { 2333 "controller": "urn:ietf:params:mud:dns" 2334 }, 2335 "ipv4": { 2336 "protocol": 17 2337 }, 2338 "udp": { 2339 "destination-port-range-or-operator": { 2340 "operator": "eq", 2341 "port": 53 2342 } 2343 } 2344 }, 2345 "actions": { 2346 "forwarding": "accept" 2347 } 2348 }, 2349 { 2350 "name": "ent1-frdev", 2351 "matches": { 2352 "ietf-mud:mud": { 2353 "controller": "urn:ietf:params:mud:ntp" 2354 }, 2355 "ipv4": { 2356 "protocol": 17 2357 }, 2358 "udp": { 2359 "destination-port-range-or-operator": { 2360 "operator": "eq", 2361 "port": 123 2362 } 2363 } 2364 }, 2365 "actions": { 2366 "forwarding": "accept" 2367 } 2368 } 2369 ] 2370 } 2371 }, 2372 { 2373 "name": "mud-59776-v6to", 2374 "type": "ipv6-acl-type", 2375 "aces": { 2376 "ace": [ 2377 { 2378 "name": "ent0-todev", 2379 "matches": { 2380 "ietf-mud:mud": { 2381 "controller": "urn:ietf:params:mud:dns" 2382 }, 2383 "ipv6": { 2384 "protocol": 17 2385 }, 2386 "udp": { 2387 "source-port-range-or-operator": { 2388 "operator": "eq", 2389 "port": 53 2390 } 2391 } 2392 }, 2393 "actions": { 2394 "forwarding": "accept" 2395 } 2396 }, 2397 { 2398 "name": "ent1-todev", 2399 "matches": { 2400 "ietf-mud:mud": { 2401 "controller": "urn:ietf:params:mud:ntp" 2402 }, 2403 "ipv6": { 2404 "protocol": 17 2405 }, 2406 "udp": { 2407 "source-port-range-or-operator": { 2408 "operator": "eq", 2409 "port": 123 2410 } 2411 } 2412 }, 2413 "actions": { 2414 "forwarding": "accept" 2415 } 2416 } 2417 ] 2418 } 2419 }, 2420 { 2421 "name": "mud-59776-v6fr", 2422 "type": "ipv6-acl-type", 2423 "aces": { 2424 "ace": [ 2425 { 2426 "name": "ent0-frdev", 2427 "matches": { 2428 "ietf-mud:mud": { 2429 "controller": "urn:ietf:params:mud:dns" 2430 }, 2431 "ipv6": { 2432 "protocol": 17 2433 }, 2434 "udp": { 2435 "destination-port-range-or-operator": { 2436 "operator": "eq", 2437 "port": 53 2438 } 2439 } 2440 }, 2441 "actions": { 2442 "forwarding": "accept" 2443 } 2444 }, 2445 { 2446 "name": "ent1-frdev", 2447 "matches": { 2448 "ietf-mud:mud": { 2449 "controller": "urn:ietf:params:mud:ntp" 2450 }, 2451 "ipv6": { 2452 "protocol": 17 2453 }, 2454 "udp": { 2455 "destination-port-range-or-operator": { 2456 "operator": "eq", 2457 "port": 123 2458 } 2459 } 2460 }, 2461 "actions": { 2462 "forwarding": "accept" 2463 } 2464 } 2465 ] 2466 } 2467 } 2469 ] 2470 } 2472 Appendix C. A Sample Extension: DETNET-indicator 2474 In this sample extension we augment the core MUD model to indicate 2475 whether the device implements DETNET. If a device later attempts to 2476 make use of DETNET, an notification or exception might be generated. 2477 Note that this example is intended only for illustrative purposes. 2479 Extension Name: "Example-Extension" (to be used in the extensions list) 2480 Standard: this document (but do not register the example) 2482 This extension augments the MUD model to include a single node, using 2483 the following sample module that has the following tree structure: 2485 module: ietf-mud-detext-example 2486 augment /ietf-mud:mud: 2487 +--rw is-detnet-required? boolean 2489 The model is defined as follows: 2491 file "ietf-mud-detext-example@2018-02-20.yang" 2492 module ietf-mud-detext-example { 2493 yang-version 1.1; 2494 namespace "urn:ietf:params:xml:ns:yang:ietf-mud-detext-example"; 2495 prefix ietf-mud-detext-example; 2497 import ietf-mud { 2498 prefix ietf-mud; 2499 } 2501 organization 2502 "IETF OPSAWG (Ops Area) Working Group"; 2503 contact 2504 "WG Web: http://tools.ietf.org/wg/opsawg/ 2505 WG List: opsawg@ietf.org 2506 Author: Eliot Lear 2507 lear@cisco.com 2508 Author: Ralph Droms 2509 rdroms@gmail.com 2510 Author: Dan Romascanu 2511 dromasca@gmail.com 2513 "; 2515 description 2516 "Sample extension to a MUD module to indicate a need 2517 for DETNET support."; 2519 revision 2018-02-20 { 2520 description 2521 "Initial revision."; 2522 reference 2523 "RFC XXXX: Manufacturer Usage Description 2524 Specification"; 2525 } 2527 augment "/ietf-mud:mud" { 2528 description 2529 "This adds a simple extension for a manufacturer 2530 to indicate whether DETNET is required by a 2531 device."; 2532 leaf is-detnet-required { 2533 type boolean; 2534 description 2535 "This value will equal true if a device requires 2536 detnet to properly function"; 2537 } 2538 } 2539 } 2540 2542 Using the previous example, we now show how the extension would be 2543 expressed: 2545 { 2546 "ietf-mud:mud": { 2547 "mud-version": 1, 2548 "mud-url": "https://lighting.example.com/lightbulb2000", 2549 "last-update": "2018-02-08T14:39:15+01:00", 2550 "cache-validity": 48, 2551 "is-supported": true, 2552 "systeminfo": "The BMS Example Lightbulb", 2553 "extensions": [ 2554 "ietf-mud-detext-example" 2555 ], 2556 "ietf-mud-detext-example:is-detnet-required": "false", 2557 "from-device-policy": { 2558 "access-lists": { 2559 "access-list": [ 2560 { 2561 "name": "mud-94934-v6fr" 2562 } 2564 ] 2565 } 2566 }, 2567 "to-device-policy": { 2568 "access-lists": { 2569 "access-list": [ 2570 { 2571 "name": "mud-94934-v6to" 2572 } 2573 ] 2574 } 2575 } 2576 }, 2577 "ietf-access-control-list:access-lists": { 2578 "acl": [ 2579 { 2580 "name": "mud-94934-v6to", 2581 "type": "ipv6-acl-type", 2582 "aces": { 2583 "ace": [ 2584 { 2585 "name": "cl0-todev", 2586 "matches": { 2587 "ipv6": { 2588 "ietf-acldns:src-dnsname": "service.bms.example.com", 2589 "protocol": 6 2590 }, 2591 "tcp": { 2592 "ietf-mud:direction-initiated": "from-device", 2593 "source-port-range-or-operator": { 2594 "operator": "eq", 2595 "port": 443 2596 } 2597 } 2598 }, 2599 "actions": { 2600 "forwarding": "accept" 2601 } 2602 } 2603 ] 2604 } 2605 }, 2606 { 2607 "name": "mud-94934-v6fr", 2608 "type": "ipv6-acl-type", 2609 "aces": { 2610 "ace": [ 2611 { 2612 "name": "cl0-frdev", 2613 "matches": { 2614 "ipv6": { 2615 "ietf-acldns:dst-dnsname": "service.bms.example.com", 2616 "protocol": 6 2617 }, 2618 "tcp": { 2619 "ietf-mud:direction-initiated": "from-device", 2620 "destination-port-range-or-operator": { 2621 "operator": "eq", 2622 "port": 443 2623 } 2624 } 2625 }, 2626 "actions": { 2627 "forwarding": "accept" 2628 } 2629 } 2630 ] 2631 } 2632 } 2633 ] 2634 } 2635 } 2637 Authors' Addresses 2639 Eliot Lear 2640 Cisco Systems 2641 Richtistrasse 7 2642 Wallisellen CH-8304 2643 Switzerland 2645 Phone: +41 44 878 9200 2646 Email: lear@cisco.com 2648 Ralph Droms 2650 Phone: +1 978 376 3731 2651 Email: rdroms@gmail.com 2653 Dan Romascanu 2655 Phone: +972 54 5555347 2656 Email: dromasca@gmail.com