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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 2845 (Obsoleted by RFC 8945) ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) ** Obsolete normative reference: RFC 5996 (Obsoleted by RFC 7296) ** Obsolete normative reference: RFC 6347 (Obsoleted by RFC 9147) Summary: 4 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 HOMENET D. Migault (Ed) 3 Internet-Draft Orange 4 Intended status: Standards Track W. Cloetens 5 Expires: April 23, 2014 SoftAtHome 6 C. Griffiths 7 Dyn 8 R. Weber 9 Nominum 10 October 20, 2013 12 IPv6 Home Network Naming Delegation 13 draft-mglt-homenet-front-end-naming-delegation-03.txt 15 Abstract 17 CPEs are designed to provide IP connectivity to home networks. Most 18 CPEs assigns IP addresses to the nodes of the home network which 19 makes it a good candidate for hosting the naming service. With IPv6, 20 the naming service makes nodes reachable from the home network as 21 well as from the Internet. 23 However, CPEs have not been designed to host such a naming service 24 exposed on the Internet. This MAY expose the CPEs to resource 25 exhaustion which would make the home network unreachable, and most 26 probably would also affect the home network inner communications. 28 In addition, DNSSEC management and configuration may not be well 29 understood or mastered by regular end users. Misconfiguration MAY 30 also results in naming service disruption, thus these end users MAY 31 prefer to rely on third party naming providers. 33 This document describes a homenet naming architecture where the CPEs 34 manage the DNS zone associates to its home network, and outsource 35 both DNSSEC management and naming service on the Internet to a third 36 party designated as the Public Authoritative Servers. 38 Status of This Memo 40 This Internet-Draft is submitted in full conformance with the 41 provisions of BCP 78 and BCP 79. 43 Internet-Drafts are working documents of the Internet Engineering 44 Task Force (IETF). Note that other groups may also distribute 45 working documents as Internet-Drafts. The list of current Internet- 46 Drafts is at http://datatracker.ietf.org/drafts/current/. 48 Internet-Drafts are draft documents valid for a maximum of six months 49 and may be updated, replaced, or obsoleted by other documents at any 50 time. It is inappropriate to use Internet-Drafts as reference 51 material or to cite them other than as "work in progress." 53 This Internet-Draft will expire on April 23, 2014. 55 Copyright Notice 57 Copyright (c) 2013 IETF Trust and the persons identified as the 58 document authors. All rights reserved. 60 This document is subject to BCP 78 and the IETF Trust's Legal 61 Provisions Relating to IETF Documents 62 (http://trustee.ietf.org/license-info) in effect on the date of 63 publication of this document. Please review these documents 64 carefully, as they describe your rights and restrictions with respect 65 to this document. Code Components extracted from this document must 66 include Simplified BSD License text as described in Section 4.e of 67 the Trust Legal Provisions and are provided without warranty as 68 described in the Simplified BSD License. 70 Table of Contents 72 1. Requirements notation . . . . . . . . . . . . . . . . . . . . 2 73 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 74 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 75 4. Architecture Overview . . . . . . . . . . . . . . . . . . . . 5 76 5. Architecture Description . . . . . . . . . . . . . . . . . . 7 77 5.1. CPE and Public Authoritative Servers Synchronization . . 8 78 5.1.1. Synchronization with a Hidden Master . . . . . . . . 8 79 5.1.2. Securing Synchronization . . . . . . . . . . . . . . 9 80 5.2. DNS Homenet Zone configuration . . . . . . . . . . . . . 10 81 5.3. DNSSEC outsourcing configuration . . . . . . . . . . . . 12 82 5.4. CPE Security Policies . . . . . . . . . . . . . . . . . . 13 83 6. Homenet Naming Configuration . . . . . . . . . . . . . . . . 13 84 7. Security Considerations . . . . . . . . . . . . . . . . . . . 14 85 7.1. Names are less secure than IP addresses . . . . . . . . . 14 86 7.2. Names are less volatile than IP addresses . . . . . . . . 15 87 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 88 9. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 15 89 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 16 90 10.1. Normative References . . . . . . . . . . . . . . . . . . 16 91 10.2. Informational References . . . . . . . . . . . . . . . . 17 92 Appendix A. Document Change Log . . . . . . . . . . . . . . . . 17 93 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 18 95 1. Requirements notation 96 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 97 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 98 document are to be interpreted as described in [RFC2119]. 100 2. Introduction 102 IPv6 provides global end to end IP reachability from the Internet and 103 into the Home Network. End Users to access services hosted in the 104 Home Network with IPv6 addresses would prefer to use names instead of 105 long and complex IPv6 addresses. 107 CPEs are already providing IPv6 connectivity to the Home Network and 108 generally provide IPv6 addresses or prefixes to the nodes of the Home 109 Network. This makes the CPEs a good candidate to manage binding 110 between names and IP addresses of the nodes. In other words, the CPE 111 is the natural candidate for setting the DNS(SEC) zone file. 113 CPEs are usually low powered devices designed for the Home Network, 114 but not for heavy traffic. As a result, hosting the a DNS service on 115 the Internet MAY expose the Home Network to resource exhaustion, 116 which may isolate the Home Network from the Internet and affect the 117 services hosted by the CPEs, thus affecting the overall Home Network 118 communications. So, this document considers that the Naming Service 119 SHOULD NOT be hosted on the CPE and SHOULD be outsourced to a third 120 party. 122 In addition, the Naming Service of the Home Network is expected to be 123 deployed with its security extension DNSSEC. DNSSEC comes with 124 complex configurations as well as complex operation management like 125 (DNSSEC secure delegation, DNSSEC key roll over, DNSSEC zone 126 updates). These operations can hardly be understood by the average 127 end user, and a misconfiguration MAY result in invalid naming 128 resolutions that MAY make an host, or the whole home network 129 unreachable. So, this document considers DNSSEC management 130 operations SHOULD NOT be handled by the average end user, but SHOULD 131 be outsourced to a third party. 133 This document describes an architecture where the CPE outsources the 134 authoritative naming service and DNSSEC zone management to a third 135 party designated as Public Authoritative Servers. It describes 136 interactions between the CPE and the Public Authoritative Servers, 137 that is to say the involved protocols and their respective 138 configurations. More specifically, this document does not describe 139 any new protocol. It provides a guide line to properly use the 140 already existing protocols. 142 This document intends to efficiently deploy DNSSEC in the Home 143 Networks in a standardized and highly flexible way. More 144 specifically, the described Home Network Naming architecture is 145 expected to lead to autoconfiguration facilities for most common 146 users, as well as enabling advanced users to have their own specific 147 settings. In fact, some end users MAY choose to host and expose a 148 Naming service on their CPE. Others MAY sign the zone on the CPE. 149 Although the document does not describe these scenarios, the 150 described architecture only requires minor modifications - such as 151 allowing incoming DNS queries from the Internet and adding the CPE in 152 the list of Naming servers. 154 The document is organized as follows. Section 4 provides an overview 155 of the homenet naming architecture and presents the CPE and the 156 Public Authoritative Server that handles the authoritative naming 157 service of the home network as well as DNSSEC management operations 158 on behalf of the CPE. Section 5 describes in details protocols and 159 configurations to set the homenet naming architecture. Section 6 160 sums up the various configuration parameters that MAY be filled by 161 the end user on the CPE for example via a GUI. Finally Section 7 162 provides security considerations. 164 3. Terminology 166 - Customer Premises Equipment: (CPE) is the router providing 167 connectivity to the home network. It is configured and managed 168 by the end user. In this document, the CPE MAY also hosts 169 services such as DHCPv6. This device MAY be provided by the 170 ISP. 172 - Registered Homenet Domain: is the Domain Name associated to the 173 home network. 175 - DNS Homenet Zone: is the DNS zone associated to the home network. 176 This zone is set by the CPE and essentially contains the 177 bindings between names and IP addresses of the nodes of the 178 home network. In this document, the CPE does neither perform 179 any DNSSEC management operations such as zone signing nor 180 provide an authoritative service for the zone. Both are 181 delegated to the Public Authoritative Server. The CPE 182 synchronizes the DNS Homenet Zone with the Public Authoritative 183 Server via a hidden master / slave architecture. The Public 184 Authoritative Server MAY use specific servers for the 185 synchronization of the DNS Homenet Zone: the Public 186 Authoritative Name Server Set as public available name servers 187 for the Registered Homenet Domain. 189 - Public Authoritative Server: performs DNSSEC management operations 190 as well as provides the authoritative service for the zone. In 191 this document, the Public Authoritative Server synchronizes the 192 DNS Homenet Zone with the CPE via a hidden master / slave 193 architecture. The Public Authoritative Server acts as a slave 194 and MAY use specific servers called Public Authoritative Name 195 Server Set. Once the Public Authoritative Server synchronizes 196 the DNS Homenet Zone, it signs the zone and generates the 197 DNSSEC Public Zone. Then the Public Authoritative Server hosts 198 the zone as an authoritative server on the Public Authoritative 199 Master(s). 201 - DNSSEC Public Zone: corresponds to the signed version of the DNS 202 Homenet Zone. It is hosted by the Public Authoritative Server, 203 which is authoritative for this zone, and is reachable on the 204 Public Authoritative Master(s). 206 - Public Authoritative Master(s): are the visible name server 207 hosting the DNSSEC Public Zone. End users' resolutions for the 208 Homenet Domain are sent to this server, and this server is a 209 master for the zone. 211 - Public Authoritative Name Server Set: is the server the CPE 212 synchronizes the DNS Homenet Zone. It is configured as a slave 213 and the CPE acts as master. The CPE sends information so the 214 DNSSEC zone can be set and served. 216 4. Architecture Overview 218 Figure 1 provides an overview of the homenet naming architecture. 220 The CPE is in charge of building the DNS Homenet Zone that contains 221 all FQDN bindings of the home network. The home network is 222 associated to a FQDN, the Registered Homenet Domain (example.com). 223 Any node in the home network is associated to a FQDN 224 (node1.example.com) that MAY be provided via DHCP or statically 225 configured on the CPE via a GUI for example. 227 The goal of the homenet naming architecture is that the CPE does not 228 handle any DNSSEC operations and does not host the authoritative 229 naming service while FQDNs in the Homenet Zone can be resolved with 230 DNSSEC by any node on the Internet. 232 In order to achieve this goal, when a node on the Internet sends a 233 DNS(SEC) query like for node1.example.com, this DNS(SEC) query MUST 234 be treated by a third party designated in figure 1 as the Public 235 Authoritative Servers. 237 The Public Authoritative Servers are in charge of DNS(SEC) traffic 238 for the Registered Homenet Domain (example.com) as well as all DNSSEC 239 management operations like zone signing, key rollover. The DNSSEC 240 zone hosted by the Public Authoritative Servers is called the DNSSEC 241 Public Zone. 243 The purpose of our architecture is to describe how the CPE can 244 outsource the DNS Homenet Zone hosted on the CPE to the DNSSEC Public 245 Zone hosted on the Public Authoritative Servers. This includes 246 description of the synchronization protocols between the CPE and the 247 Public Authoritative Servers in Section 5.1 as well as configurations 248 of the DNS Homenet Zone Section 5.2. 250 home network +-------------------+ Internet 251 | | 252 | CPE | 253 | | +----------------------+ 254 +-------+ |+-----------------+| | Public Authoritative | 255 | | || DNS Homenet Zone|| | Servers | 256 | node1 | || || |+--------------------+| 257 | | || Homenet Domain || || DNSSEC Public Zone || 258 +-------+ || Name ||=========|| || 259 || (example.com) || ^ || (example.com) || 260 node1.\ |+-----------------+| | |+--------------------+| 261 example.com +-------------------+ | +----------------------+ 262 | ^ | 263 Synchronization | | 264 | | 265 DNSSEC resolution for node1.example.com | v 266 +----------------------+ 267 | | 268 | DNSSEC Resolver | 269 | | 270 +----------------------+ 272 Figure 1: Homenet Naming Architecture Description 274 The content of the DNS Homenet Zone is out of the scope of this 275 document. The CPE MAY host multiple services like a web GUI, DHCP 276 [RFC6644] or mDNS [RFC6762]. These services MAY coexist and MAY be 277 used to populate the DNS Homenet Zone. This document assumes the DNS 278 Homenet Zone has been populated with domain names that are intended 279 to be publicly published and that are publicly reachable. More 280 specifically, names associated to services or devices that are not 281 expected to be reachable from outside the home network or names bound 282 to non globally reachable IP addresses MUST NOT be part of the DNS 283 Homenet Zone. 285 Because services or devices MAY only be reached from hosts in the 286 home network, DNS resolution MAY be handled differently from inside 287 the network and from outside the network.This is out of scope of this 288 document. This document is focused on outsourcing the DNS Homenet 289 Zone to the DNS Public Authoritative Servers that are visible from 290 outside the home network. How to deal with a homenet view and a 291 public view is out of the scope of this document. In order to deal 292 with different views, some CPE MAY host DNS forwarders or use DNS 293 view mechanisms. 295 This document does not make any other assumption on the DNS Homenet 296 Zone that records MUST be made public. More specifically, the DNS 297 Homenet Zone can be a regular or a reverse zone with PTR RRsets. A 298 CPE SHOULD consider both the normal zone as well as the reverse zone 299 and outsource them both to the designated Public Authoritative 300 Servers. 302 By outsourcing to Public Authoritative Servers, services or devices 303 mentioned in the DNS Homenet Zone MAY be not reachable in case the 304 home network has no internet connectivity. How to keep the naming 305 service within the home network when the it is disconnected from the 306 public internet is out of scope of this document. CPE MAY chose for 307 example to host an authoritative naming server for the home network 308 or use a DNS forwarders. 310 Similarly, CPE MAY host a DNS(SEC) resolution service for nodes in 311 the home network. There are multiple ways to configure the resolver 312 service on the CPE. Detailing these various configurations is out of 313 the scope of this document, and is considered as an implementation 314 issue. Some implementers MAY chose to forward DNS(SEC) queries from 315 the home network to the resolving server of its ISP or any other 316 public resolver. In that case, the DNS(SEC) response from the Public 317 Authoritative Servers is forwarded to the home network, which provide 318 DNS and DNSSEC resolution for the home network. Note also that in 319 this case, the naming service depends on the connectivity with the 320 resolving servers. In case the home network is disconnected, the 321 naming service MAY not be available. Alternative implementations MAY 322 chose to take advantage of forwarders and lookup in the DNS Homenet 323 Zone. This MAY provide only DNS responses in the home network if the 324 CPE does not sign the DNS Homenet Zone. Other implementation MAY 325 chose to synchronize the DNSSEC Public Zone on the CPE either using 326 DNS master slave mechanisms, or by caching the whole zone. This 327 latest option MAY require some additional configuration the Public 328 Authoritative Servers. 330 5. Architecture Description 331 This section describes how the CPE and the Public Authoritative 332 Servers SHOULD be configured to outsource authoritative naming 333 service as well as DNSSEC management operations. Section 5.1 334 describes how a secure synchronization between the CPE and the Public 335 Authoritative server is set. Section 5.2 provides guide lines for 336 the DNS Homenet Zone set in the CPE and uploaded on the Public 337 Authoritative Servers. Section 5.3 describes DNSSEC settings on the 338 Public Authoritative Servers. Finally, Section 5.4 provides the 339 security policies that SHOULD be set on the CPE. 341 5.1. CPE and Public Authoritative Servers Synchronization 343 5.1.1. Synchronization with a Hidden Master 345 Uploading and dynamically updating the zone file on the Public 346 Servers can be seen as zone provisioning between the CPE (Hidden 347 Master) and the Public Server (Slave Server). This can be handled 348 either in band or out of band. DNS dynamic update [RFC2136] may be 349 used. However, in this section we detail how to take advantage of 350 the DNS slave / master architecture to deploy updates to public 351 zones. 353 The Public Authoritative Server is configured as a slave for the 354 Homenet Domain Name. This slave configuration has been previously 355 agreed between the end user and the provider of the Public 356 Authoritative Servers. In order to set the master/ slave 357 architecture, the CPE acts as a Hidden Master Server, which is a 358 regular Authoritative DNS(SEC) Server listening on the WAN interface. 360 The Hidden Master Server is expected to accept SOA [RFC1033], AXFR 361 [RFC1034], and IXFR [RFC1995] queries from its configured slave DNS 362 servers. The Hidden Master Server SHOULD send NOTIFY messages 363 [RFC1996] in order to update Public DNS server zones as updates 364 occur. Because, DNS Homenet Zones are likely to be small, CPE MUST 365 implement AXFR and SHOULD implement IXFR. 367 Hidden Master Server differs from a regular authoritative server for 368 the home network by: 370 - Interface Binding: the Hidden Master Server listens on the WAN 371 Interface, whereas a regular authoritative server for the home 372 network would listen on the home network interface. 374 - Limited exchanges: the purpose of the Hidden Master Server is to 375 synchronizes with the Public Authoritative Servers, not to 376 serve zone. As a result, exchanges are performed with specific 377 nodes (the Public Authoritative Servers). Then exchange types 378 are limited. The only legitimate exchanges are: NOTIFY 379 initiated by the Hidden Master and IXFR or AXFR exchanges 380 initiated by the Public Authoritative Servers. On the other 381 hand regular authoritative servers would respond any hosts on 382 the home network, and any DNS(SEC) query would be considered. 383 The CPE SHOULD filter IXFR/AXFR traffic and drop traffic not 384 initiated by the Public Authoritative Server. The CPE MUST 385 listen for DNS on TCP and UDP and at least allow SOA lookups to 386 the DNS Homenet Zone. 388 5.1.2. Securing Synchronization 390 Exchange between the Public Servers and the CPE MUST be secured, at 391 least for integrity protection and for authentication. This is the 392 case whatever mechanism is used between the CPE and the Public 393 Authoritative DNS(SEC) Servers. 395 TSIG [RFC2845] or SIG(0) [RFC2931] can be used to secure the DNS 396 communications between the CPE and the Public DNS(SEC) Servers. TSIG 397 uses a symmetric key which can be managed by TKEY [RFC2930]. 398 Management of the key involved in SIG(0) is performed through zone 399 updates. How to roll the keys with SIG(0) is out-of-scope of this 400 document. The advantage of these mechanisms is that they are only 401 associated with the DNS application. Not relying on shared libraries 402 ease testing and integration. On the other hand, using TSIG, TKEY or 403 SIG(0) requires that these mechanisms to be implemented on the 404 DNS(SEC) Server's implementation running on the CPE, which adds 405 codes. Another disadvantage is that TKEY does not provides 406 authentication mechanism. 408 Protocols like TLS [RFC5246] / DTLS [RFC6347] can be used to secure 409 the transactions between the Public Authoritative Servers and the 410 CPE. The advantage of TLS/DTLS is that this technology is widely 411 deployed, and most of the boxes already embeds a TLS/DTLS libraries, 412 eventually taking advantage of hardware acceleration. Then TLS/DTLS 413 provides authentication facilities and can use certificates to 414 authenticate the Public Authoritative Server and the CPE. On the 415 other hand, using TLS/DTLS requires to integrate DNS exchange over 416 TLS/DTLS, as well as a new service port. This is why we do not 417 recommend this option. 419 IPsec [RFC4301] IKEv2 [RFC5996] can also be used to secure the 420 transactions between the CPE and the Public Authoritative Servers. 421 Similarly to TLS/DTLS, most CPE already embeds a IPsec stack, and 422 IKEv2 provides multiple authentications possibilities with its EAP 423 framework. In addition, IPsec can be used to protect the DNS 424 exchanges between the CPE and the Public Authoritative Servers 425 without any modifications of the DNS Servers or client. DNS 426 integration over IPsec only requires an additional security policy in 427 the Security Policy Database. One disadvantage of IPsec is that it 428 hardly goes through NATs and firewalls. However, in our case, the 429 CPE is connected to the Internet, and IPsec communication between the 430 CPE and Public Authoritative Server SHOULD NOT be impacted by middle 431 boxes. 433 As mentioned above, TSIG, IPsec and TLS/DTLS may be used to secure 434 transactions between the CPE and the Public Authentication Servers. 435 The CPE and Public Authoritative Server SHOULD implement TSIG and 436 IPsec. 438 How the PSK can be used by any of the TSIG, TLS/DTLS or IPsec 439 protocols. Authentication based on certificates implies a mutual 440 authentication and thus requires the CPE to manage a private key, a 441 public key or certificates as well as Certificate Authorities. This 442 adds complexity to the configuration especially on the CPE side. For 443 this reason, we recommend that CPE MAY use PSK or certificate base 444 authentication and that Public Authentication Servers MUST support 445 PSK and certificate based authentication. 447 5.2. DNS Homenet Zone configuration 449 As depicted in figure 1, he DNSSEC Public Zone is hosted on the 450 Public Authoritative Server, whereas the DNS Homenet Zone is hosted 451 on the CPE. As a result, the CPE MUST configure the DNS Homenet Zone 452 as if the DNS Homenet Zone were hosted by the Public Authoritative 453 Servers instead of the CPE. 455 If one considers the case where the CPE has a single Homenet Domain 456 Name and has an agreement with a single Public Authoritative Server. 457 In that case, the DNS Homenet Zone SHOULD configure its Name Server 458 RRset and Start of Authority with the ones associated to the Public 459 Authoritative Servers. This is illustrated in figure 2. 460 public.autho.servers.example.net is the domain name associated to the 461 Public Authoritative Server, and IP1, IP2, IP3, IP4 are the IP 462 addresses associated. 464 $ORIGIN example.com 465 $TTL 1h 467 @ IN SOA public.autho.servers.example.net 468 hostmaster.example.com. ( 469 2013120710 ; serial number of this zone file 470 1d ; slave refresh 471 2h ; slave retry time in case of a problem 472 4w ; slave expiration time 473 1h ; maximum caching time in case of failed 474 ; lookups 475 ) 477 @ NS public.authoritative.servers.example.net 479 public.autho.servers.example.net A @IP1 480 public.autho.servers.example.net A @IP2 481 public.autho.servers.example.net AAAA @IP3 482 public.autho.servers.example.net AAAA @IP4 484 Figure 2: DNS Homenet Zone 486 The SOA RRset is defined in [RFC1033], [RFC1035]. This SOA is 487 specific as it is used for the synchronization between the Hidden 488 Master and the Public Authoritative Name Server Set and published on 489 the DNS Public Authoritative Master. 491 - MNAME: indicates the primary master. In our case the zone is 492 published on the Public Authoritative Master, and its name MUST 493 be mentioned. If multiple Public Authoritative Masters are 494 involved, one of them MUST be chosen. More specifically, the 495 CPE MUST NOT place the name of the Hidden Master. 497 - RNAME: indicates the email address to reach the administrator. 498 [RFC2142] recommends to use hostmaster@domain and replacing the 499 '@' sign by '.'. 501 - REFRESH and RETRY: indicate respectively in seconds how often 502 slaves need to check the master and the time between two 503 refresh when a refresh has failed. Default value indicated by 504 [RFC1033] are 3600 (1 hour) for refresh and 600 (10 minutes) 505 for retry. This value MAY be long for highly dynamic content. 506 However, Public Authoritative Masters and the CPE are expected 507 to implement NOTIFY [RFC1996]. Then short values MAY increase 508 the bandwidth usage for slaves hosting large number of zones. 509 As a result, default values looks fine. 511 EXPIRE: is the upper limit data SHOULD be kept in absence of 512 refresh. Default value indicated by [RFC1033] is 3600000 about 513 42 days. In home network architectures, the CPE provides both 514 the DNS synchronization and the access to the home network. 515 This device MAY be plug / unplugged by the end user without 516 notification, thus we recommend large period. 518 MINIMUM: indicates the minimum TTL. Default value indicated by 519 [RFC1033] is 86400 (1 day). For home network, this value MAY 520 be reduced, and 3600 (1hour) seems more appropriated. 522 When the end user considers multiple Public Authoritative Servers for 523 a given Registered Homenet Domain, the DNS Homenet Zone MAY contain 524 all associated Name Servers and IP addresses. 526 Some additional verification can check whether the CPE IP address is 527 mentioned in the Public Zone file, and raise a warning to the End 528 User. 530 5.3. DNSSEC outsourcing configuration 532 In this document we assumed that the Public Authoritative Server 533 signs the DNS Homenet Zone. Multiple variants MAY be proposed by the 534 Public Authoritative Servers. Public Authoritative Servers MAY 535 propose to sign the DNS Homenet Zone with keys generated by the 536 Public Authoritative Servers and unknown to the CPE. Alternatively 537 some MAY propose the end user to provide the private keys. Although 538 not considered in this document some end user MAY still prefer to 539 sign their zone with their own keys they do not communicate to the 540 Public Authoritative Servers. All these alternatives result from a 541 negotiation between the end user and the Public Authoritative 542 Servers. This negotiation is performed out-of-band and is out of 543 scope of this document. 545 In this document, we consider that the Public Authoritative Server 546 has all the necessary cryptographic elements to perform zone signing 547 and key management operations. 549 Note that Public Authoritative Servers described in this document 550 accomplish different functions, and thus different entities MAY be 551 involved. 553 - DNS Slave function synchronizes the DNS Homenet Zone between the 554 CPE and the Public Authoritative Servers. The DNS Homenet Zone 555 on the Public Authoritative Servers is not available, and the 556 Public Authoritative Server MUST NOT address any DNS queries 557 for that zone. As a result, the Public Authoritative Servers 558 MAY chose a dedicated set of servers to serve the DNS Homenet 559 Zone: the Public Authoritative Name Server Set. 561 - DNS Zone Signing function signs the DNS Zone Homenet Zone to 562 generate an DNSSEC Public Zone. 564 - DNSSEC Authoritative Server hosts the naming service for the DNSSEC 565 Public Zone. Any DNS(SEC) query associated to the Homenet Zone 566 SHOULD be done using the specific servers designated as the 567 Public Authoritative Master(s). 569 5.4. CPE Security Policies 571 This section details security policies related to the Hidden Master / 572 Slave synchronization. 574 The Hidden Master, as described in this document SHOULD drop any 575 queries from the home network. This can be performed with port 576 binding and/or firewall rules. 578 The Hidden Master SHOULD drop on the WAN interface any DNS queries 579 that is not issued from the Public Authoritative Server Name Server 580 Set. 582 The Hidden Master SHOULD drop any outgoing packets other than DNS 583 NOTIFY query, SOA response, IXFR response or AXFR responses. 585 The Hidden Master SHOULD drop any incoming packets other than DNS 586 NOTIFY response, SOA query, IXFR query or AXFR query. 588 The Hidden Master SHOULD drop any non protected IXFR or AXFR 589 exchange. This depends how the synchronization is secured. 591 6. Homenet Naming Configuration 593 This section specifies the various parameters required by the CPE to 594 configure the naming architecture of this document. This section is 595 informational, and is intended to clarify the information handled by 596 the CPE and the various settings to be done. 598 Public Authoritative Servers MAY be defined with the following 599 parameters. These parameters are necessary to establish a secure 600 channel between the CPE and the Public Authoritative Server, and to 601 set the appropriated DNS Homenet Zone file: 603 - Public Authoritative Name Server Set: The associated FQDNs or IP 604 addresses of the Public Authoritative Server. IP addresses are 605 optional and the FQDN is sufficient. To secure the binding 606 name and IP addresses, a DNSSEC exchange is required. 607 Otherwise, the IP addresses SHOULD be entered manually. 609 - Authentication Method: How the CPE authenticates itself to the 610 Public Server. This MAY depend on the implementation but we 611 should consider at least IPsec, DTLS and TSIG 613 - Authentication data: Associated Data. PSK only requires a single 614 argument. If other authentication mechanisms based on 615 certificates are used, then, files for the CPE private keys, 616 certificates and certification authority SHOULD be specified. 618 - Public Authoritative Master(s): The FQDN or IP addresses of the 619 Public Authoritative Master. It MAY correspond to the data 620 that will be set in the NS RRsets and SOA of the DNS Homenet 621 Zone. IP addresses are optional and the FQDN is sufficient. 622 To secure the binding name and IP addresses, a DNSSEC exchange 623 is required. Otherwise, the IP addresses SHOULD be entered 624 manually. 626 - Registered Homenet Domain: The domain name the Public 627 Authoritative is configured for DNS slave, DNSSEC zone signing 628 and DNSSEC zone hosting. 630 Setting the DNS Homenet Zone requires the following information. 632 - Registered Homenet Domain: The Domain Name of the zone. Multiple 633 Registered Homenet Domain MAY be provided. This will generate 634 the creation of multiple DNS Homenet Zones. 636 - Public Authoritative Server: The Public Authoritative Servers 637 associated to the Registered Homenet Domain. Multiple Public 638 Authoritative Server MAY be provided. 640 7. Security Considerations 642 The Homenet Naming Architecture described in this document solves 643 exposing the CPE's DNS service as a DoS attack vector. 645 7.1. Names are less secure than IP addresses 646 This document describes how an End User can make his services and 647 devices from his Home Network reachable on the Internet with Names 648 rather than IP addresses. This exposes the Home Network to attackers 649 since names are expected to provide less randomness than IP 650 addresses. The naming delegation protects the End User's privacy by 651 not providing the complete zone of the Home Network to the ISP. 652 However, using the DNS with names for the Home Network exposes the 653 Home Network and its components to dictionary attacks. In fact, with 654 IP addresses, the Interface Identifier is 64 bit length leading to 655 2^64 possibilities for a given subnetwork. This is not to mention 656 that the subnet prefix is also of 64 bit length, thus providing 657 another 2^64 possibilities. On the other hand, names used either for 658 the Home Network domain or for the devices present less randomness 659 (livebox, router, printer, nicolas, jennifer, ...) and thus exposes 660 the devices to dictionary attacks. 662 7.2. Names are less volatile than IP addresses 664 IP addresses may be used to locate a device, a host or a Service. 665 However, Home Networks are not expected to be assigned the same 666 Prefix over time. As a result observing IP addresses provides some 667 ephemeral information about who is accessing the service. On the 668 other hand, Names are not expected to be as volatile as IP addresses. 669 As a result, logging Names, over time, may be more valuable that 670 logging IP addresses, especially to profile End User's 671 characteristics. 673 PTR provides a way to bind an IP address to a Name. In that sense 674 responding to PTR DNS queries may affect the End User's Privacy. For 675 that reason we recommend that End Users may choose to respond or not 676 to PTR DNS queries and may return a NXDOMAIN response. 678 8. IANA Considerations 680 This document has no actions for IANA. 682 9. Acknowledgment 684 The authors wish to thank Philippe Lemordant for its contributions on 685 the early versions of the draft, Ole Troan for pointing out issues 686 with the IPv6 routed home concept and placing the scope of this 687 document in a wider picture, Mark Townsley for encouragement and 688 injecting a healthy debate on the merits of the idea, Ulrik de Bie 689 for providing alternative solutions, Paul Mockapetris, Christian 690 Jacquenet, Francis Dupont and Ludovic Eschard for their remarks on 691 CPE and low power devices, Olafur Gudmundsson for clarifying DNSSEC 692 capabilities of small devices, Simon Kelley for its feedback as 693 dnsmasq implementer. 695 10. References 697 10.1. Normative References 699 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 700 STD 13, RFC 1034, November 1987. 702 [RFC1035] Mockapetris, P., "Domain names - implementation and 703 specification", STD 13, RFC 1035, November 1987. 705 [RFC1995] Ohta, M., "Incremental Zone Transfer in DNS", RFC 1995, 706 August 1996. 708 [RFC1996] Vixie, P., "A Mechanism for Prompt Notification of Zone 709 Changes (DNS NOTIFY)", RFC 1996, August 1996. 711 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 712 Requirement Levels", BCP 14, RFC 2119, March 1997. 714 [RFC2136] Vixie, P., Thomson, S., Rekhter, Y., and J. Bound, 715 "Dynamic Updates in the Domain Name System (DNS UPDATE)", 716 RFC 2136, April 1997. 718 [RFC2142] Crocker, D., "MAILBOX NAMES FOR COMMON SERVICES, ROLES AND 719 FUNCTIONS", RFC 2142, May 1997. 721 [RFC2845] Vixie, P., Gudmundsson, O., Eastlake, D., and B. 722 Wellington, "Secret Key Transaction Authentication for DNS 723 (TSIG)", RFC 2845, May 2000. 725 [RFC2930] Eastlake, D., "Secret Key Establishment for DNS (TKEY 726 RR)", RFC 2930, September 2000. 728 [RFC2931] Eastlake, D., "DNS Request and Transaction Signatures ( 729 SIG(0)s)", RFC 2931, September 2000. 731 [RFC4301] Kent, S. and K. Seo, "Security Architecture for the 732 Internet Protocol", RFC 4301, December 2005. 734 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 735 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 737 [RFC5996] Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen, 738 "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC 739 5996, September 2010. 741 [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 742 Security Version 1.2", RFC 6347, January 2012. 744 [RFC6644] Evans, D., Droms, R., and S. Jiang, "Rebind Capability in 745 DHCPv6 Reconfigure Messages", RFC 6644, July 2012. 747 [RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762, 748 February 2013. 750 10.2. Informational References 752 [RFC1033] Lottor, M., "Domain administrators operations guide", RFC 753 1033, November 1987. 755 Appendix A. Document Change Log 757 [RFC Editor: This section is to be removed before publication] 759 -03: 761 *Simon's comments taken into consideration 763 *Adding SOA, PTR considerations 765 *Removing DNSSEC performance paragraphs on low power devices 767 *Adding SIG(0) as a mechanism for authenticating the servers 769 *Goals clarification: the architecture described in the document 1) 770 does not describe new protocols, and 2) can be adapted to specific 771 cases for advance users. 773 -02: 775 *remove interfaces: "Public Authoritative Server Naming Interface" is 776 replaced by "Public Authoritative Master(s)". "Public Authoritative 777 Server Management Interface" is replaced by "Public Authoritative 778 Name Server Set". 780 -01.3: 782 *remove the authoritative / resolver services of the CPE. 783 Implementation dependent 785 *remove interactions with mdns and dhcp. Implementation dependent. 787 *remove considerations on low powered devices 789 *remove position toward homenet arch 791 *remove problem statement section 792 -01.2: 794 * add a CPE description to show that the architecture can fit CPEs 796 * specification of the architecture for very low powered devices. 798 * integrate mDNS and DHCP interactions with the Homenet Naming 799 Architecture. 801 * Restructuring the draft. 1) We start from the homenet-arch draft 802 to derive a Naming Architecture, then 2) we show why CPE need 803 mechanisms that do not expose them to the Internet, 3) we describe 804 the mechanisms. 806 * I remove the terminology and expose it in the figures A and B. 808 * remove the Front End Homenet Naming Architecture to Homenet Naming 810 -01: 812 * Added C. Griffiths as co-author. 814 * Updated section 5.4 and other sections of draft to update section 815 on Hidden Master / Slave functions with CPE as Hidden Master/Homenet 816 Server. 818 * For next version, address functions of MDNS within Homenet Lan and 819 publishing details northbound via Hidden Master. 821 -00: First version published. 823 Authors' Addresses 825 Daniel Migault 826 Orange 827 38 rue du General Leclerc 828 92794 Issy-les-Moulineaux Cedex 9 829 France 831 Phone: +33 1 45 29 60 52 832 Email: mglt.ietf@gmail.com 833 Wouter Cloetens 834 SoftAtHome 835 vaartdijk 3 701 836 3018 Wijgmaal 837 Belgium 839 Email: wouter.cloetens@softathome.com 841 Chris Griffiths 842 Dyn 843 150 Dow Street 844 Manchester, NH 03101 845 US 847 Email: cgriffiths@dyn.com 848 URI: http://dyn.com 850 Ralf Weber 851 Nominum 852 2000 Seaport Blvd #400 853 Redwood City, CA 94063 854 US 856 Email: ralf.weber@nominum.com 857 URI: http://www.nominum.com