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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IPv6 Operations T. Chown 3 Internet-Draft University of Southampton 4 Intended status: Informational March 27, 2007 5 Expires: September 28, 2007 7 IPv6 Implications for Network Scanning 8 draft-ietf-v6ops-scanning-implications-03 10 Status of this Memo 12 By submitting this Internet-Draft, each author represents that any 13 applicable patent or other IPR claims of which he or she is aware 14 have been or will be disclosed, and any of which he or she becomes 15 aware will be disclosed, in accordance with Section 6 of BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six months 23 and may be updated, replaced, or obsoleted by other documents at any 24 time. It is inappropriate to use Internet-Drafts as reference 25 material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt. 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html. 33 This Internet-Draft will expire on September 28, 2007. 35 Copyright Notice 37 Copyright (C) The IETF Trust (2007). 39 Abstract 41 The 128 bits of IPv6 address space is considerably bigger than the 32 42 bits of address space of IPv4. In particular, the IPv6 subnets to 43 which hosts attach will by default have 64 bits of host address 44 space. As a result, traditional methods of remote TCP or UDP network 45 scanning to discover open or running services on a host will 46 potentially become less feasible, due to the larger search space in 47 the subnet. In addition automated attacks, such as those performed 48 by network worms, that pick random host addresses to propagate to, 49 may be hampered. This document discusses this property of IPv6 and 50 describes related issues for IPv6 site network administrators to 51 consider, which may be of importance when planning site address 52 allocation and management strategies. While traditional network 53 scanning probes (whether by individuals or automated via network 54 worms) may become less common, administrators should be aware of 55 other methods attackers may use to discover IPv6 addresses on a 56 target network, and also be aware of appropriate measures to mitigate 57 them. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 62 2. Target Address Space for Network Scanning . . . . . . . . . . 4 63 2.1. IPv4 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 2.2. IPv6 . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 65 2.3. Reducing the IPv6 Search Space . . . . . . . . . . . . . . 4 66 2.4. Dual-stack Networks . . . . . . . . . . . . . . . . . . . 5 67 2.5. Defensive Scanning . . . . . . . . . . . . . . . . . . . . 5 68 3. Alternatives for Attackers: Off-link . . . . . . . . . . . . . 5 69 3.1. Gleaning IPv6 prefix information . . . . . . . . . . . . . 6 70 3.2. DNS Advertised Hosts . . . . . . . . . . . . . . . . . . . 6 71 3.3. DNS Zone Transfers . . . . . . . . . . . . . . . . . . . . 6 72 3.4. Log File Analysis . . . . . . . . . . . . . . . . . . . . 6 73 3.5. Application Participation . . . . . . . . . . . . . . . . 6 74 3.6. Multicast Group Addresses . . . . . . . . . . . . . . . . 7 75 3.7. Transition Methods . . . . . . . . . . . . . . . . . . . . 7 76 4. Alternatives for Attackers: On-link . . . . . . . . . . . . . 7 77 4.1. General on-link methods . . . . . . . . . . . . . . . . . 7 78 4.2. Intra-site Multicast or Other Service Discovery . . . . . 8 79 5. Site Administrator Tools . . . . . . . . . . . . . . . . . . . 8 80 5.1. IPv6 Privacy Addresses . . . . . . . . . . . . . . . . . . 8 81 5.2. Cryptographically Generated Addresses (CGAs) . . . . . . . 9 82 5.3. Non-use of MAC addresses in EUI-64 format . . . . . . . . 9 83 5.4. DHCP Service Configuration Options . . . . . . . . . . . . 9 84 5.5. Rolling Server Addresses . . . . . . . . . . . . . . . . . 10 85 5.6. Application-Specific Addresses . . . . . . . . . . . . . . 10 86 6. Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . 10 87 7. Security Considerations . . . . . . . . . . . . . . . . . . . 11 88 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 89 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11 90 10. Informative References . . . . . . . . . . . . . . . . . . . . 11 91 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 92 Intellectual Property and Copyright Statements . . . . . . . . . . 13 94 1. Introduction 96 One of the key differences between IPv4 and IPv6 is the much larger 97 address space for IPv6, which also goes hand-in-hand with much larger 98 subnet sizes. This change has a significant impact on the 99 feasibility of TCP and UDP network scanning, whereby an automated 100 process is run to detect open ports (services) on systems that may 101 then be subject of a subsequent attack. Today many IPv4 sites are 102 subjected to such probing on a recurring basis. 104 The 128 bits of IPv6 [1] address space is considerably bigger than 105 the 32 bits of address space in IPv4. In particular, the IPv6 106 subnets to which hosts attach will by default have 64 bits of host 107 address space [2]. As a result, traditional methods of remote TCP or 108 UDP network scanning to discover open or running services on a host 109 will potentially become less feasible, due to the larger search space 110 in the subnet. This document discusses this property of IPv6, and 111 describes related issues for IPv6 site network administrators to 112 consider, which may be of importance when planning site address 113 allocation and management strategies. 115 This document complements the transition-centric discussion of the 116 issues that can be found in Appendix A of the IPv6 Transition/ 117 Co-existence Security Considerations text [12], which takes a broad 118 view of security issues for transitioning networks. 120 The reader is also referred to a recent paper by Bellovin on worm 121 propagation strategies in IPv6 networks [13]. This paper discusses 122 some of the issues included in this document, from a slightly 123 different perspective. 125 Network scanning is quite a prevalent tactic used by would-be 126 attackers. There are two general classes of such scanning. In one 127 case, the probes are from an attacker outside a site boundary who is 128 trying to find weaknesses on any system in that network which they 129 may then subsequently be able to compromise. The other case is 130 scanning by worms that spread through (site) networks, looking for 131 further hosts to compromise. Many worms, like Slammer, rely on such 132 address scanning methods to propagate, whether they pick subnets 133 numerically (and thus probably topologically) close to the current 134 victim, or subnets in random remote networks. 136 It must be remembered that the defence of a network must not rely 137 solely on the unpredictable sparseness of the host addresses on that 138 network. Such a feature or property is only one measure in a set of 139 measures that may be applied. However, with a growth in usage of 140 IPv6 devices in open networks likely, and security becoming more 141 likely an issue for the end devices, such obfuscation can be useful 142 where its use is of little or no cost to the administrator to 143 implement it. However, a law of diminishing returns does apply. An 144 administrator who undertakes an address hiding policy through 145 unpredictable sparseness should be aware that while IPv6 host 146 addresses may be assigned to hosts that are likely to take 147 significant time to discover by traditional scanning methods, there 148 are other means by which such addresses may be discovered. 149 Implementing all of the mitigating methods described in this text may 150 be deemed unwarranted effort. But it is up to the site administrator 151 to be aware of the context and the options available, and in 152 particular what new methods may attackers use to glean IPv6 address 153 information, and how these can potentially be mitigated against. 154 Finally, note that this document is currently intended to be 155 informational; there is not yet sufficient deployment experience for 156 it to be considered BCP. 158 2. Target Address Space for Network Scanning 160 There are significantly different considerations for the feasibility 161 of plain, brute force IPv4 and IPv6 address scanning. 163 2.1. IPv4 165 A typical IPv4 subnet may have 8 bits reserved for host addressing. 166 In such a case, a remote attacker need only probe at most 256 167 addresses to determine if a particular service is running publicly on 168 a host in that subnet. Even at only one probe per second, such a 169 scan would take under 5 minutes to complete. 171 2.2. IPv6 173 A typical IPv6 subnet will have 64 bits reserved for host addressing. 174 In such a case, a remote attacker in principle needs to probe 2^64 175 addresses to determine if a particular open service is running on a 176 host in that subnet. At a very conservative one probe per second, 177 such a scan may take some 5 billion years to complete. A more rapid 178 probe will still be limited to (effectively) infinite time for the 179 whole address space. However, there are ways for the attacker to 180 reduce the address search space to scan against within the target 181 subnet, as we discuss below. 183 2.3. Reducing the IPv6 Search Space 185 The IPv6 host address space through which an attacker may search can 186 be reduced in at least two ways. 188 First, the attacker may rely on the administrator conveniently 189 numbering their hosts from [prefix]::1 upward. This makes scanning 190 trivial, and thus should be avoided unless the host's address is 191 readily obtainable from other sources (for example it is the site's 192 published primary DNS or email MX server). Alternatively if hosts 193 are numbered sequentially, or using any regular scheme, knowledge of 194 one address may expose other available addresses to scan. 196 Second, in the case of statelessly autoconfiguring [1] hosts, the 197 host part of the address will usually take a well-known format that 198 includes the Ethernet vendor prefix and the "fffe" stuffing. For 199 such hosts, the search space can be reduced to 48 bits. Further, if 200 the Ethernet vendor is also known, the search space may be reduced to 201 24 bits, with a one probe per second scan then taking a less daunting 202 194 days. Even where the exact vendor is not known, using a set of 203 common vendor prefixes can reduce the search. In addition, many 204 nodes in a site network may be procured in batches, and thus have 205 sequential or near sequential MAC addresses; if one node's 206 autoconfigured address is known, scanning around that address may 207 yield results for the attacker. Again, any form of sequential host 208 addressing should be avoided if possible. 210 2.4. Dual-stack Networks 212 Full advantage of the increased IPv6 address space in terms of 213 resilience to network scanning may not be gained until IPv6-only 214 networks and devices become more commonplace, given that most IPv6 215 hosts are currently dual stack, with (more readily scannable) IPv4 216 connectivity. However, many applications or services (e.g. new peer- 217 to-peer applications) on the (dual stack) hosts may emerge that are 218 only accessible over IPv6, and that thus can only be discovered by 219 IPv6 address scanning. 221 2.5. Defensive Scanning 223 The problem faced by the attacker for an IPv6 network is also faced 224 by a site administrator looking for vulnerabilities in their own 225 network's systems. The administrator should have the advantage of 226 being on-link for scanning purposes though. 228 3. Alternatives for Attackers: Off-link 230 If IPv6 hosts in subnets are allocated addresses 'randomly', and as a 231 result IPv6 network scanning becomes relatively infeasible, attackers 232 will need to find new methods to identify IPv6 addresses for 233 subsequent scanning. In this section, we discuss some possible paths 234 attackers may take. In these cases, the attacker will attempt to 235 identify specific IPv6 addresses for subsequent targeted probes. 237 3.1. Gleaning IPv6 prefix information 239 Note that in IPv6 an attacker would not be able to search across the 240 entire IPv6 address space as they might in IPv4. An attacker may 241 learn general prefixes to focus their efforts on by observing route 242 view information (e.g. from public looking glass services) or 243 information on allocated address space from RIRs. In general this 244 would only yield information at most at the /48 prefix granularity, 245 but specific /64 prefixes may be observed from route views on some 246 parts of some networks. 248 3.2. DNS Advertised Hosts 250 Any servers that are DNS listed, e.g. MX mail relays, or web 251 servers, will remain open to probing from the very fact that their 252 IPv6 addresses will be published in the DNS. Where a site uses 253 sequential host numbering, publishing just one address may lead to a 254 threat upon the other hosts. 256 Sites may use a two-faced DNS where internal system DNS information 257 is only published in an internal DNS. It is also worth noting that 258 the reverse DNS tree may also expose address information. In such 259 cases, populating the reverse DNS tree for the entire subnet, even if 260 not all addresses are actually used, may reduce that exposure. 262 3.3. DNS Zone Transfers 264 In the IPv6 world a DNS zone transfer is much more likely to narrow 265 the number of hosts an attacker needs to target. This implies 266 restricting zone transfers is (more) important for IPv6, even if it 267 is already good practice to restrict them in the IPv4 world. 269 There are some projects that provide Internet mapping data from 270 access to such transfers. Administrators may of course agree to 271 provide such transfers where they choose to do so. 273 3.4. Log File Analysis 275 IPv6 addresses may be harvested from recorded logs such as web site 276 logs. Anywhere else where IPv6 addresses are explicitly recorded may 277 prove a useful channel for an attacker, e.g. by inspection of the 278 (many) Received from: or other header lines in archived email or 279 Usenet news messages. 281 3.5. Application Participation 283 More recent peer-to-peer applications often include some centralised 284 server which coordinates the transfer of data between peers. The 285 BitTorrent application builds swarms of nodes that exchange chunks of 286 files, with a tracker passing information about peers with available 287 chunks of data between the peers. Such applications may offer an 288 attacker a source of peer IP addresses to probe. 290 3.6. Multicast Group Addresses 292 Where an Embedded RP [7] multicast group address is known, the 293 unicast address of the rendezvous point is implied by the group 294 address. Where unicast prefix based multicast group addresses [5] 295 are used, specific /64 link prefixes may also be disclosed in traffic 296 that goes off-site. An administrator may thus choose to put aside 297 /64 bit prefixes for multicast group addresses that are not in use 298 for normal unicast routing and addressing. Alternatively a site may 299 simply use their /48 site prefix allocation to generate RFC3306 300 multicast group addresses. 302 3.7. Transition Methods 304 Specific knowledge of the target network may be gleaned if that 305 attacker knows it is using 6to4 [4], ISATAP [10], Teredo [11] or 306 other techniques that derive low-order bits from IPv4 addresses 307 (though in this case, unless they are using IPv4 NAT, the IPv4 308 addresses may be probed anyway). 310 For example, the current Microsoft 6to4 implementation uses the 311 address 2002:V4ADDR::V4ADDR while older Linux and FreeBSD 312 implementations default to 2002:V4ADDR::1. This leads to specific 313 knowledge of specific hosts in the network. Given one host in the 314 network is observed as using a given transition technique, it is 315 likely that there are more. 317 In the case of Teredo, the 64 bit node identifier is generated from 318 the IPv4 address observed at a Teredo server along with a UDP port 319 number. The Teredo specification also allows for discovery of other 320 Teredo clients on the same IPv4 subnet via a well-known IPv4 321 multicast address (see Section 2.17 of RFC4380 [11]). 323 4. Alternatives for Attackers: On-link 325 4.1. General on-link methods 327 If the attacker is on link, then traffic on the link, be it Neighbour 328 Discovery or application based traffic, can invariably be observed, 329 and target addresses learnt. In this document we are assuming the 330 attacker is off link, but traffic to or from other nodes (in 331 particular server systems) is likely to show up if an attacker can 332 gain a presence on any one subnet in a site's network. 334 IPv6-enabled hosts on local subnets may be discovered through probing 335 the "all hosts" link local multicast address. Likewise any routers 336 on link may be found via the "all routers" link local multicast 337 address. An attacker may choose to probe in a slightly more 338 obfuscated way by probing the solicited node multicast address of a 339 potential target host. 341 Where a host has already been compromised, its Neighbour Discovery 342 cache is also likely to include information about active nodes on 343 link, just as an ARP cache would do for IPv4. 345 4.2. Intra-site Multicast or Other Service Discovery 347 A site may also have site or organisational scope multicast 348 configured, in which case application traffic, or service discovery, 349 may be exposed site wide. An attacker may also choose to use any 350 other service discovery methods supported by the site. 352 5. Site Administrator Tools 354 There are some tools that site administrators can apply to make the 355 task for IPv6 network scanning attackers harder. These methods arise 356 from the considerations in the previous section. 358 The author notes that at his current (university) site, there is no 359 evidence of general network scanning running across subnets. 360 However, there is network scanning over IPv6 connections to systems 361 whose IPv6 addresses are advertised (DNS servers, MX relays, web 362 servers, etc), which are presumably looking for other open ports on 363 these hosts to probe. 365 5.1. IPv6 Privacy Addresses 367 By using the IPv6 Privacy Extensions [3] hosts in a network may only 368 be able to connect to external systems using their current 369 (temporary) privacy address. While an attacker may be able to port 370 scan that address if they do so quickly upon observing or otherwise 371 learning of the address, the threat or risk is reduced due to the 372 time-constrained value of the address. One implementation of RFC3041 373 already deployed has privacy addresses active for one day, with such 374 addresses reachable for seven days. 376 Note that an RFC3041 host will usually also have a separate static 377 global IPv6 address by which it can also be reached, and that may be 378 DNS-advertised if an externally reachable service is running on it. 380 DHCPv6 can be used to serve normal global addresses and IPv6 Privacy 381 Addresses. 383 The implication is that while Privacy Addresses can mitigate the 384 long-term value of harvested addresses, an attacker creating an IPv6 385 application server to which clients connect will still be able to 386 probe the clients by their Privacy Address as and when they visit 387 that server. The duration for which Privacy Addresses are valid will 388 impact on the usefulness of such observed addresses to an external 389 attacker. The frequency with which such address get recycled could 390 be increased, though this may increase the complexity of local 391 network management for the administrator, since doing so will cause 392 more addresses to be used over time in the site. 394 It may be worth exploring whether firewalls can be adapted to allow 395 the option to block traffic initiated to a known IPv6 Privacy Address 396 from outside a network boundary. While some applications may 397 genuinely require such capability, it may be useful to be able to 398 differentiate in some circumstances. 400 5.2. Cryptographically Generated Addresses (CGAs) 402 The use of Cryptographically Generated Addresses (CGAs) [9] may also 403 cause the search space to be increased from that presented by default 404 use of Stateless Autoconfiguration. Such addresses would be seen 405 where Secure Neighbour Discovery (SEND) [8] is in use. 407 5.3. Non-use of MAC addresses in EUI-64 format 409 The EUI-64 identifier format does not require the use of MAC 410 addresses for identifier construction. At least one well-known 411 operating system currently defaults to generation of the 64 bit 412 interface identifier by use of random bits, and thus does not embed 413 the MAC address. Where such a method exists as an option, an 414 administrator may wish consider use of that option. 416 5.4. DHCP Service Configuration Options 418 The administrator should configure DHCPv6 so that the first addresses 419 allocated from the pool begins much higher in the address space than 420 at [prefix]::1. Further, it is desirable that allocated addresses 421 are not sequential, nor have any predictable pattern to them. 422 Unpredictable sparseness in the allocated addresses is a desirable 423 property. DHCPv6 implementors should support configuration options 424 to allow such behaviour. 426 DHCPv6 also includes an option to use Privacy Extension [3] 427 addresses, i.e. temporary addresses, as described in Section 12 of 428 the DHCPv6 [6] specification. 430 5.5. Rolling Server Addresses 432 Given the huge address space in an IPv6 subnet/link, and the support 433 for IPv6 multiaddressing, whereby a node or interface may have 434 multiple IPv6 valid addresses of which one is preferred for sending, 435 it may be possible to periodically change the advertised addresses 436 that certain long standing services use (where 'short' exchanges to 437 those services are used). 439 For example, an MX server could be assigned a new primary address on 440 a weekly basis, and old addresses expired monthly. Where MX server 441 IP addresses are detected and cached by spammers, such a defence may 442 prove useful to reduce spam volumes, especially as such IP lists may 443 also be passed between potential attackers for subsequent probing. 445 5.6. Application-Specific Addresses 447 By a similar reasoning, it may be possible to consider using 448 application-specific addresses for systems, such that a given 449 application may have exclusive use of an address, meaning that 450 disclosure of the address should not expose other applications or 451 services running on the same system. 453 6. Conclusions 455 Due to the much larger size of IPv6 subnets in comparison to IPv4 it 456 will become less feasible for network scanning methods to detect open 457 services for subsequent attacks. If administrators number their IPv6 458 subnets in 'random', non-predictable ways, attackers, whether they be 459 in the form of automated network scanners or dynamic worm 460 propagation, will need to use new methods to determine IPv6 host 461 addresses to target. Of course, if those systems are dual-stack, and 462 have open IPv4 services running, they will remain exposed to 463 traditional probes over IPv4 transport. 465 This document has discussed the considerations a site administrator 466 should bear in mind when considering IPv6 address planning issues and 467 configuring various service elements. It highlights relevant issues 468 and offers some informational guidance for administrators. While 469 some suggestions are currently more practical than others, it is up 470 to individual administrators to determine how much effort they wish 471 to invest in 'address hiding' schemes, given that this is only one 472 aspect of network security, and certainly not one to rely solely 473 upon. But by implementing the basic principle of allocating 474 addresses on the basis of unpredictable sparseness, some level of 475 obfuscation can be cheaply deployed. 477 7. Security Considerations 479 There are no specific security considerations in this document 480 outside of the topic of discussion itself. 482 8. IANA Considerations 484 There are no IANA considerations for this document. 486 9. Acknowledgements 488 Thanks are due to people in the 6NET project (www.6net.org) for 489 discussion of this topic, including Pekka Savola, Christian Strauf 490 and Martin Dunmore, as well as other contributors from the IETF v6ops 491 and other mailing lists, including Tony Finch, David Malone, Bernie 492 Volz, Fred Baker, Andrew Sullivan, Tony Hain, Dave Thaler and Alex 493 Petrescu. 495 10. Informative References 497 [1] Deering, S. and R. Hinden, "Internet Protocol, Version 6 (IPv6) 498 Specification", RFC 2460, December 1998. 500 [2] Thomson, S. and T. Narten, "IPv6 Stateless Address 501 Autoconfiguration", RFC 2462, December 1998. 503 [3] Narten, T. and R. Draves, "Privacy Extensions for Stateless 504 Address Autoconfiguration in IPv6", RFC 3041, January 2001. 506 [4] Carpenter, B. and K. Moore, "Connection of IPv6 Domains via 507 IPv4 Clouds", RFC 3056, February 2001. 509 [5] Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6 510 Multicast Addresses", RFC 3306, August 2002. 512 [6] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. 513 Carney, "Dynamic Host Configuration Protocol for IPv6 514 (DHCPv6)", RFC 3315, July 2003. 516 [7] Savola, P. and B. Haberman, "Embedding the Rendezvous Point 517 (RP) Address in an IPv6 Multicast Address", RFC 3956, 518 November 2004. 520 [8] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure 521 Neighbor Discovery (SEND)", RFC 3971, March 2005. 523 [9] Aura, T., "Cryptographically Generated Addresses (CGA)", 524 RFC 3972, March 2005. 526 [10] Templin, F., Gleeson, T., Talwar, M., and D. Thaler, "Intra- 527 Site Automatic Tunnel Addressing Protocol (ISATAP)", RFC 4214, 528 October 2005. 530 [11] Huitema, C., "Teredo: Tunneling IPv6 over UDP through Network 531 Address Translations (NATs)", RFC 4380, February 2006. 533 [12] Davies, E., Krishnan, S., and P. Savola, "IPv6 Transition/ 534 Co-existence Security Considerations 535 (draft-ietf-v6ops-security-overview-06)", October 2007. 537 [13] Bellovin, S. et al, "Worm Propagation Strategies in an IPv6 538 Internet (http://www.cs.columbia.edu/~smb/papers/v6worms.pdf)", 539 ;login:, February 2006. 541 Author's Address 543 Tim Chown 544 University of Southampton 545 Southampton, Hampshire SO17 1BJ 546 United Kingdom 548 Email: tjc@ecs.soton.ac.uk 550 Full Copyright Statement 552 Copyright (C) The IETF Trust (2007). 554 This document is subject to the rights, licenses and restrictions 555 contained in BCP 78, and except as set forth therein, the authors 556 retain all their rights. 558 This document and the information contained herein are provided on an 559 "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS 560 OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND 561 THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS 562 OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF 563 THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED 564 WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. 566 Intellectual Property 568 The IETF takes no position regarding the validity or scope of any 569 Intellectual Property Rights or other rights that might be claimed to 570 pertain to the implementation or use of the technology described in 571 this document or the extent to which any license under such rights 572 might or might not be available; nor does it represent that it has 573 made any independent effort to identify any such rights. 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