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Gont 3 Internet-Draft UTN-FRH / SI6 Networks 4 Intended status: Informational W. Liu 5 Expires: May 3, 2018 Huawei Technologies 6 R. Bonica 7 Juniper Networks 8 October 30, 2017 10 Recommendations on the Filtering of IPv6 Packets Containing IPv6 11 Extension Headers 12 draft-ietf-opsec-ipv6-eh-filtering-04 14 Abstract 16 It is common operator practice to mitigate security risks by 17 enforcing appropriate packet filtering. This document analyzes both 18 the general security implications of IPv6 Extension Headers and the 19 specific security implications of each Extension Header and Option 20 type. Additionally, it discusses the operational and 21 interoperability implications of discarding packets based on the IPv6 22 Extension Headers and IPv6 options they contain. Finally, it 23 provides advice on the filtering of such IPv6 packets at transit 24 routers for traffic *not* directed to them, for those cases in which 25 such filtering is deemed as necessary. 27 Status of This Memo 29 This Internet-Draft is submitted in full conformance with the 30 provisions of BCP 78 and BCP 79. 32 Internet-Drafts are working documents of the Internet Engineering 33 Task Force (IETF). Note that other groups may also distribute 34 working documents as Internet-Drafts. The list of current Internet- 35 Drafts is at https://datatracker.ietf.org/drafts/current/. 37 Internet-Drafts are draft documents valid for a maximum of six months 38 and may be updated, replaced, or obsoleted by other documents at any 39 time. It is inappropriate to use Internet-Drafts as reference 40 material or to cite them other than as "work in progress." 42 This Internet-Draft will expire on May 3, 2018. 44 Copyright Notice 46 Copyright (c) 2017 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents 51 (https://trustee.ietf.org/license-info) in effect on the date of 52 publication of this document. Please review these documents 53 carefully, as they describe your rights and restrictions with respect 54 to this document. Code Components extracted from this document must 55 include Simplified BSD License text as described in Section 4.e of 56 the Trust Legal Provisions and are provided without warranty as 57 described in the Simplified BSD License. 59 Table of Contents 61 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 62 2. Terminology and Conventions Used in This Document . . . . . . 4 63 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 64 2.2. Applicability Statement . . . . . . . . . . . . . . . . . 4 65 2.3. Conventions . . . . . . . . . . . . . . . . . . . . . . . 4 66 3. IPv6 Extension Headers . . . . . . . . . . . . . . . . . . . 5 67 3.1. General Discussion . . . . . . . . . . . . . . . . . . . 5 68 3.2. General Security Implications . . . . . . . . . . . . . . 6 69 3.3. Summary of Advice on the Handling of IPv6 Packets with 70 Specific IPv6 Extension Headers . . . . . . . . . . . . . 6 71 3.4. Advice on the Handling of IPv6 Packets with Specific IPv6 72 Extension Headers . . . . . . . . . . . . . . . . . . . . 7 73 3.5. Advice on the Handling of Packets with Unknown IPv6 74 Extension Headers . . . . . . . . . . . . . . . . . . . . 16 75 4. IPv6 Options . . . . . . . . . . . . . . . . . . . . . . . . 17 76 4.1. General Discussion . . . . . . . . . . . . . . . . . . . 17 77 4.2. General Security Implications of IPv6 Options . . . . . . 17 78 4.3. Advice on the Handling of Packets with Specific IPv6 79 Options . . . . . . . . . . . . . . . . . . . . . . . . . 17 80 4.4. Advice on the handling of Packets with Unknown IPv6 81 Options . . . . . . . . . . . . . . . . . . . . . . . . . 28 82 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 83 6. Security Considerations . . . . . . . . . . . . . . . . . . . 29 84 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 29 85 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 29 86 8.1. Normative References . . . . . . . . . . . . . . . . . . 29 87 8.2. Informative References . . . . . . . . . . . . . . . . . 33 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 90 1. Introduction 92 Recent studies (see e.g. [RFC7872]) suggest that there is widespread 93 dropping of IPv6 packets that contain IPv6 Extension Headers (EHs). 94 In some cases, such packet drops occur at transit routers. While 95 some operators "officially" drop packets that contain IPv6 EHs, it is 96 possible that some of the measured packet drops be the result of 97 improper configuration defaults, or inappropriate advice in this 98 area. 100 This document analyzes both the general security implications of IPv6 101 EHs and the specific security implications of each EH and Option 102 type, and provides advice on the filtering of IPv6 packets based on 103 the IPv6 EHs and the IPv6 options they contain. Since various 104 protocols may use IPv6 EHs (possibly with IPv6 options), discarding 105 packets based on the IPv6 EHs or IPv6 options they contain may have 106 implications on the proper functioning of such protocols. Thus, this 107 document also attempts to discuss the operational and 108 interoperability implications of such filtering policies. 110 The filtering policy typically depends on where in the network such 111 policy is enforced: when the policy is enforced in a transit network, 112 the policy typically follows a "black-list" approach, where only 113 packets with clear negative implications are dropped. On the other 114 hand, when the policy is enforced closer to the destination systems, 115 the policy typically follows a "white-list" approach, where only 116 traffic that is expected to be received is allowed. The advice in 117 this document is aimed only at transit routers that may need to 118 enforce a filtering policy based on the EHs and IPv6 options a packet 119 may contain, following a "black-list" approach, and hence is likely 120 to be much more permissive that a filtering policy to be employed 121 e.g. at the edge of an enterprise network. The advice in this 122 document is meant to improve the current situation of the dropping of 123 packets with IPv6 EHs in the Internet [RFC7872]. 125 This document is similar in nature to [RFC7126], which addresses the 126 same problem for the IPv4 case. However, in IPv6, the problem space 127 is compounded by the fact that IPv6 specifies a number of IPv6 EHs, 128 and a number of IPv6 options which may be valid only when included in 129 specific EH types. 131 This document completes and complements the considerations for 132 protecting the control plane from packets containing IP options that 133 can be found in [RFC6192]. 135 Section 2 of this document specifies the terminology and conventions 136 employed throughout this document. Section 3 of this document 137 discusses IPv6 EHs and provides advice in the area of filtering IPv6 138 packets that contain such IPv6 EHs. Section 4 of this document 139 discusses IPv6 options and provides advice in the area of filtering 140 IPv6 packets that contain such options. 142 2. Terminology and Conventions Used in This Document 144 2.1. Terminology 146 The terms "fast path", "slow path", and associated relative terms 147 ("faster path" and "slower path") are loosely defined as in Section 2 148 of [RFC6398]. 150 The terms "permit" (allow the traffic), "drop" (drop with no 151 notification to sender), and "reject" (drop with appropriate 152 notification to sender) are employed as defined in [RFC3871]. 153 Throughout this document we also employ the term "discard" as a 154 generic term to indicate the act of discarding a packet, irrespective 155 of whether the sender is notified of such drops, and irrespective of 156 whether the specific filtering action is logged. 158 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 159 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 160 document are to be interpreted as described in [RFC2119]. 162 2.2. Applicability Statement 164 This document provides advice on the filtering of IPv6 packets with 165 EHs at transit routers for traffic *not* explicitly destined to such 166 transit routers, for those cases in which such filtering is deemed as 167 necessary. 169 2.3. Conventions 171 This document assumes that nodes comply with the requirements in 172 [RFC7045]. Namely (from [RFC7045]), 174 o If a forwarding node discards a packet containing a standard IPv6 175 EH, it MUST be the result of a configurable policy and not just 176 the result of a failure to recognise such a header. 178 o The discard policy for each standard type of EH MUST be 179 individually configurable. 181 o The default configuration SHOULD allow all standard IPv6 EHs. 183 The advice provided in this document is only meant to guide an 184 operator in configuring forwarding devices, and is *not* to be 185 interpreted as advice regarding default configuration settings for 186 network devices. That is, this document provides advice with respect 187 to operational configurations, but does not change the implementation 188 defaults required by [RFC7045]. 190 We recommend that configuration options are made available to govern 191 the processing of each IPv6 EH type and each IPv6 option type. Such 192 configuration options may include the following possible settings: 194 o Permit this IPv6 EH or IPv6 Option type 196 o Discard (and log) packets containing this IPv6 EH or option type 198 o Reject (and log) packets containing this IPv6 EH or option type 199 (where the packet drop is signaled with an ICMPv6 error message) 201 o Rate-limit traffic containing this IPv6 EH or option type 203 o Ignore this IPv6 EH or option type (as if it was not present) and 204 forward the packet. We note that if a packet carries forwarding 205 information (e.g., in an IPv6 Routing Header) this might be an 206 inappropriate or undesirable action. 208 We note that special care needs to be taken when devices log packet 209 drops/rejects. Devices should count the number of packets dropped/ 210 rejected, but the logging of drop/reject events should be limited so 211 as to not overburden device resources. 213 Finally, we note that when discarding packets, it is generally 214 desirable that the sender be signaled of the packet drop, since this 215 is of use for trouble-shooting purposes. However, throughout this 216 document (when recommending that packets be discarded) we generically 217 refer to the action as "discard" without specifying whether the 218 sender is signaled of the packet drop. 220 3. IPv6 Extension Headers 222 3.1. General Discussion 224 IPv6 [RFC8200] EHs allow for the extension of the IPv6 protocol. 225 Since both IPv6 EHs and upper-layer protocols share the same 226 namespace ("Next Header" registry/namespace), [RFC7045] identifies 227 which of the currently assigned Internet Protocol numbers identify 228 IPv6 EHs vs. upper-layer protocols. This document discusses the 229 filtering of packets based on the IPv6 EHs (as specified by 230 [RFC7045]) they contain. 232 NOTE: [RFC7112] specifies that non-fragmented IPv6 datagrams and 233 IPv6 First-Fragments MUST contain the entire IPv6 header chain 234 [RFC7112]. Therefore, intermediate systems can enforce the 235 filtering policies discussed in this document, or resort to simply 236 discarding the offending packets when they fail to comply with the 237 requirements in [RFC7112]. We note that, in order to implement 238 filtering rules on the fast path, it may be necessary for the 239 filtering device to limit the depth into the packet that can be 240 inspected before giving up. In circumstances where there is such 241 a limitation, it is recommended that implementations discard 242 packets if, when trying to determine whether to discard or permit 243 a packet, the aforementioned limit is encountered. 245 3.2. General Security Implications 247 In some specific device architectures, IPv6 packets that contain IPv6 248 EHs may cause the corresponding packets to be processed on the slow 249 path, and hence may be leveraged for the purpose of Denial of Service 250 (DoS) attacks [I-D.gont-v6ops-ipv6-ehs-packet-drops] [Cisco-EH] 251 [FW-Benchmark]. 253 Operators are urged to consider IPv6 EH filtering and IPv6 options 254 handling capabilities of different devices as they make deployment 255 decisions in future. 257 3.3. Summary of Advice on the Handling of IPv6 Packets with Specific 258 IPv6 Extension Headers 260 This section summarizes the advice provided in Section 3.4, providing 261 references to the specific sections in which a detailed analysis can 262 be found. 264 +----------------------------+---------------------+----------------+ 265 | EH type | Filtering policy | Reference | 266 +----------------------------+---------------------+----------------+ 267 | IPv6 Hop-by-Hop Options | Drop or Ignore | Section 3.4.1 | 268 | (Proto=0) | | | 269 +----------------------------+---------------------+----------------+ 270 | Routing Header for IPv6 | Drop only RTH0, | Section 3.4.2 | 271 | (Proto=43) | Permit other RH | | 272 | | Types | | 273 +----------------------------+---------------------+----------------+ 274 | Fragment Header for IPv6 | Permit | Section 3.4.3 | 275 | (Proto=44) | | | 276 +----------------------------+---------------------+----------------+ 277 | Encapsulating Security | Permit | Section 3.4.4 | 278 | Payload (Proto=50) | | | 279 +----------------------------+---------------------+----------------+ 280 | Authentication Header | Permit | Section 3.4.5 | 281 | (Proto=51) | | | 282 +----------------------------+---------------------+----------------+ 283 | Destination Options for | Permit | Section 3.4.6 | 284 | IPv6 (Proto=60) | | | 285 +----------------------------+---------------------+----------------+ 286 | Mobility Header | Permit | Section 3.4.7 | 287 | (Proto=135) | | | 288 +----------------------------+---------------------+----------------+ 289 | Host Identity Protocol | Permit | Section 3.4.8 | 290 | (Proto=139) | | | 291 +----------------------------+---------------------+----------------+ 292 | Shim6 Protocol (Proto=140) | Permit | Section 3.4.9 | 293 +----------------------------+---------------------+----------------+ 294 | Use for experimentation | Drop | Section 3.4.10 | 295 | and testing (Proto=253 and | | | 296 | 254) | | | 297 +----------------------------+---------------------+----------------+ 299 Table 1: Summary of Advice on the Handling of IPv6 Packets with 300 Specific IPv6 Extension Headers 302 3.4. Advice on the Handling of IPv6 Packets with Specific IPv6 303 Extension Headers 305 3.4.1. IPv6 Hop-by-Hop Options (Protocol Number=0) 307 3.4.1.1. Uses 309 The Hop-by-Hop Options header is used to carry optional information 310 that may be examined by every node along a packet's delivery path. 312 It is expected that nodes will examine the Hop-by-Hop Options header 313 if explicitly configured to do so. 315 NOTE: [RFC2460] required that all nodes examined and processed the 316 Hop-by-Hop Options header. However, even before the publication of 317 [RFC8200] a number of implementations already provided the option of 318 ignoring this header unless explicitly configured to examine it. 320 3.4.1.2. Specification 322 This EH is specified in [RFC8200]. At the time of this writing, the 323 following options have been specified for the Hop-by-Hop Options EH: 325 o Type 0x00: Pad1 [RFC8200] 327 o Type 0x01: PadN [RFC8200] 329 o Type 0x05: Router Alert [RFC2711] 331 o Type 0x07: CALIPSO [RFC5570] 333 o Type 0x08: SMF_DPD [RFC6621] 335 o Type 0x26: Quick-Start [RFC4782] 337 o Type 0x4D: (Deprecated) 339 o Type 0x63: RPL Option [RFC6553] 341 o Type 0x6D: MPL Option [RFC7731] 343 o Type 0x8A: Endpoint Identification (Deprecated) 344 [draft-ietf-nimrod-eid] 346 o Type 0xC2: Jumbo Payload [RFC2675] 348 o Type 0xEE: IPv6 DFF Header [RFC6971] 350 o Type 0x1E: RFC3692-style Experiment [RFC4727] 352 o Type 0x3E: RFC3692-style Experiment [RFC4727] 354 o Type 0x5E: RFC3692-style Experiment [RFC4727] 356 o Type 0x7E: RFC3692-style Experiment [RFC4727] 358 o Type 0x9E: RFC3692-style Experiment [RFC4727] 359 o Type 0xBE: RFC3692-style Experiment [RFC4727] 361 o Type 0xDE: RFC3692-style Experiment [RFC4727] 363 o Type 0xFE: RFC3692-style Experiment [RFC4727] 365 3.4.1.3. Specific Security Implications 367 Legacy nodes that may process this extencion header could be subject 368 to Denial of Service attacks. 370 NOTE: While [RFC8200] has removed this requirement, the deployed base 371 may still reflect the traditional behavior for a while, and hence the 372 potential security problems of this EH are still of concern. 374 3.4.1.4. Operational and Interoperability Impact if Blocked 376 Discarding packets containing a Hop-by-Hop Options EH would break any 377 of the protocols that rely on it for proper functioning. For 378 example, it would break RSVP [RFC2205] and multicast deployments, and 379 would cause IPv6 jumbograms to be discarded. 381 3.4.1.5. Advice 383 Nodes implementing [RFC8200] would already ignore this extension 384 header unless explicitly required to process it. For legacy 385 ([RFC2460] nodes, the recommended configuration for the processing of 386 these packets depends on the features and capabilities of the 387 underlying platform. On platforms that allow forwarding of packets 388 with HBH Options on the fast path, we recommend that packets with a 389 HBH Options EH be forwarded as normal. Otherwise, on platforms in 390 which processing of packets with a IPv6 HBH Options EH is carried out 391 in the slow path, and an option is provided to rate-limit these 392 packets, we recommend that this option be selected. Finally, when 393 packets containing a HBH Options EH are processed in the slow-path, 394 and the underlying platform does not have any mitigation options 395 available for attacks based on these packets, we recommend that such 396 platforms discard packets containing IPv6 HBH Options EHs. 398 Finally, we note that, for obvious reasons, RPL (Routing Protocol for 399 Low-Power and Lossy Networks) [RFC6550] routers must not discard 400 packets based on the presence of an IPv6 Hop-by-Hop Options EH. 402 3.4.2. Routing Header for IPv6 (Protocol Number=43) 403 3.4.2.1. Uses 405 The Routing header is used by an IPv6 source to list one or more 406 intermediate nodes to be "visited" on the way to a packet's 407 destination. 409 3.4.2.2. Specification 411 This EH is specified in [RFC8200]. [RFC2460] had originally 412 specified the Routing Header Type 0, which was later obsoleted by 413 [RFC5095], and thus removed from [RFC8200]. 415 At the time of this writing, the following Routing Types have been 416 specified: 418 o Type 0: Source Route (DEPRECATED) [RFC2460] [RFC5095] 420 o Type 1: Nimrod (DEPRECATED) 422 o Type 2: Type 2 Routing Header [RFC6275] 424 o Type 3: RPL Source Route Header [RFC6554] 426 o Types 4-252: Unassigned 428 o Type 253: RFC3692-style Experiment 1 [RFC4727] 430 o Type 254: RFC3692-style Experiment 2 [RFC4727] 432 o Type 255: Reserved 434 3.4.2.3. Specific Security Implications 436 The security implications of RHT0 have been discussed in detail in 437 [Biondi2007] and [RFC5095]. 439 3.4.2.4. Operational and Interoperability Impact if Blocked 441 Blocking packets containing a RHT0 or RTH1 has no operational 442 implications. However, blocking packets employing other routing 443 header types will break the protocols that rely on them. 445 3.4.2.5. Advice 447 Intermediate systems should discard packets containing a RHT0 or 448 RHT1. RHT2 and RHT3 should be permitted, as required by [RFC7045]. 449 Other routing header types should be discarded. 451 3.4.3. Fragment Header for IPv6 (Protocol Number=44) 453 3.4.3.1. Uses 455 This EH provides the fragmentation functionality for IPv6. 457 3.4.3.2. Specification 459 This EH is specified in [RFC8200]. 461 3.4.3.3. Specific Security Implications 463 The security implications of the Fragment Header range from Denial of 464 Service attacks (e.g. based on flooding a target with IPv6 fragments) 465 to information leakage attacks [RFC7739]. 467 3.4.3.4. Operational and Interoperability Impact if Blocked 469 Blocking packets that contain a Fragment Header will break any 470 protocol that may rely on fragmentation (e.g., the DNS [RFC1034]). 472 3.4.3.5. Advice 474 Intermediate systems should permit packets that contain a Fragment 475 Header. 477 3.4.4. Encapsulating Security Payload (Protocol Number=50) 479 3.4.4.1. Uses 481 This EH is employed for the IPsec suite [RFC4303]. 483 3.4.4.2. Specification 485 This EH is specified in [RFC4303]. 487 3.4.4.3. Specific Security Implications 489 Besides the general implications of IPv6 EHs, this EH could be 490 employed to potentially perform a DoS attack at the destination 491 system by wasting CPU resources in validating the contents of the 492 packet. 494 3.4.4.4. Operational and Interoperability Impact if Blocked 496 Discarding packets that employ this EH would break IPsec deployments. 498 3.4.4.5. Advice 500 Intermediate systems should permit packets containing the 501 Encapsulating Security Payload EH. 503 3.4.5. Authentication Header (Protocol Number=51) 505 3.4.5.1. Uses 507 The Authentication Header can be employed for provide authentication 508 services in IPv4 and IPv6. 510 3.4.5.2. Specification 512 This EH is specified in [RFC4302]. 514 3.4.5.3. Specific Security Implications 516 Besides the general implications of IPv6 EHs, this EH could be 517 employed to potentially perform a DoS attack at the destination 518 system by wasting CPU resources in validating the contents of the 519 packet. 521 3.4.5.4. Operational and Interoperability Impact if Blocked 523 Discarding packets that employ this EH would break IPsec deployments. 525 3.4.5.5. Advice 527 Intermediate systems should permit packets containing an 528 Authentication Header. 530 3.4.6. Destination Options for IPv6 (Protocol Number=60) 532 3.4.6.1. Uses 534 The Destination Options header is used to carry optional information 535 that needs be examined only by a packet's destination node(s). 537 3.4.6.2. Specification 539 This EH is specified in [RFC8200]. At the time of this writing, the 540 following options have been specified for this EH: 542 o Type 0x00: Pad1 [RFC8200] 544 o Type 0x01: PadN [RFC8200] 545 o Type 0x04: Tunnel Encapsulation Limit [RFC2473] 547 o Type 0x4D: (Deprecated) 549 o Type 0xC9: Home Address [RFC6275] 551 o Type 0x8A: Endpoint Identification (Deprecated) 552 [draft-ietf-nimrod-eid] 554 o Type 0x8B: ILNP Nonce [RFC6744] 556 o Type 0x8C: Line-Identification Option [RFC6788] 558 o Type 0x1E: RFC3692-style Experiment [RFC4727] 560 o Type 0x3E: RFC3692-style Experiment [RFC4727] 562 o Type 0x5E: RFC3692-style Experiment [RFC4727] 564 o Type 0x7E: RFC3692-style Experiment [RFC4727] 566 o Type 0x9E: RFC3692-style Experiment [RFC4727] 568 o Type 0xBE: RFC3692-style Experiment [RFC4727] 570 o Type 0xDE: RFC3692-style Experiment [RFC4727] 572 o Type 0xFE: RFC3692-style Experiment [RFC4727] 574 3.4.6.3. Specific Security Implications 576 No security implications are known, other than the general 577 implications of IPv6 EHs. For a discussion of possible security 578 implications of specific options specified for the DO header, please 579 see the Section 4.3. 581 3.4.6.4. Operational and Interoperability Impact if Blocked 583 Discarding packets that contain a Destination Options header would 584 break protocols that rely on this EH type for conveying information, 585 including protocols such as ILNP [RFC6740] and Mobile IPv6 [RFC6275], 586 and IPv6 tunnels that employ the Tunnel Encapsulation Limit option. 588 3.4.6.5. Advice 590 Intermediate systems should permit packets that contain a Destination 591 Options Header. 593 3.4.7. Mobility Header (Protocol Number=135) 595 3.4.7.1. Uses 597 The Mobility Header is an EH used by mobile nodes, correspondent 598 nodes, and home agents in all messaging related to the creation and 599 management of bindings in Mobile IPv6. 601 3.4.7.2. Specification 603 This EH is specified in [RFC6275]. 605 3.4.7.3. Specific Security Implications 607 A thorough security assessment of the security implications of the 608 Mobility Header and related mechanisms can be found in Section 15 of 609 [RFC6275]. 611 3.4.7.4. Operational and Interoperability Impact if Blocked 613 Discarding packets containing this EH would break Mobile IPv6. 615 3.4.7.5. Advice 617 Intermediate systems should permit packets containing this EH. 619 3.4.8. Host Identity Protocol (Protocol Number=139) 621 3.4.8.1. Uses 623 This EH is employed with the Host Identity Protocol (HIP), an 624 experimental protocol that allows consenting hosts to securely 625 establish and maintain shared IP-layer state, allowing separation of 626 the identifier and locator roles of IP addresses, thereby enabling 627 continuity of communications across IP address changes. 629 3.4.8.2. Specification 631 This EH is specified in [RFC5201]. 633 3.4.8.3. Specific Security Implications 635 The security implications of the HIP header are discussed in detail 636 in Section 8 of [RFC6275]. 638 3.4.8.4. Operational and Interoperability Impact if Blocked 640 Discarding packets that contain the Host Identity Protocol would 641 break HIP deployments. 643 3.4.8.5. Advice 645 Intermediate systems should permit packets that contain a Host 646 Identity Protocol EH. 648 3.4.9. Shim6 Protocol (Protocol Number=140) 650 3.4.9.1. Uses 652 This EH is employed by the Shim6 [RFC5533] Protocol. 654 3.4.9.2. Specification 656 This EH is specified in [RFC5533]. 658 3.4.9.3. Specific Security Implications 660 The specific security implications are discussed in detail in 661 Section 16 of [RFC5533]. 663 3.4.9.4. Operational and Interoperability Impact if Blocked 665 Discarding packets that contain this EH will break Shim6. 667 3.4.9.5. Advice 669 Intermediate systems should permit packets containing this EH. 671 3.4.10. Use for experimentation and testing (Protocol Numbers=253 and 672 254) 674 3.4.10.1. Uses 676 These IPv6 EHs are employed for performing RFC3692-Style experiments 677 (see [RFC3692] for details). 679 3.4.10.2. Specification 681 These EHs are specified in [RFC3692] and [RFC4727]. 683 3.4.10.3. Specific Security Implications 685 The security implications of these EHs will depend on their specific 686 use. 688 3.4.10.4. Operational and Interoperability Impact if Blocked 690 For obvious reasons, discarding packets that contain these EHs limits 691 the ability to perform legitimate experiments across IPv6 routers. 693 3.4.10.5. Advice 695 Intermediate systems should discard packets containing these EHs. 696 Only in specific scenarios in which RFC3692-Style experiments are to 697 be performed should these EHs be permitted. 699 3.5. Advice on the Handling of Packets with Unknown IPv6 Extension 700 Headers 702 We refer to IPv6 EHs that have not been assigned an Internet Protocol 703 Number by IANA (and marked as such) in [IANA-PROTOCOLS] as "unknown 704 IPv6 extension headers" ("unknown IPv6 EHs"). 706 3.5.1. Uses 708 New IPv6 EHs may be specified as part of future extensions to the 709 IPv6 protocol. 711 Since IPv6 EHs and Upper-layer protocols employ the same namespace, 712 it is impossible to tell whether an unknown "Internet Protocol 713 Number" is being employed for an IPv6 EH or an Upper-Layer protocol. 715 3.5.2. Specification 717 The processing of unknown IPv6 EHs is specified in [RFC8200] and 718 [RFC7045]. 720 3.5.3. Specific Security Implications 722 For obvious reasons, it is impossible to determine specific security 723 implications of unknown IPv6 EHs. However, from security standpoint, 724 a device should discard IPv6 extension headers for which the security 725 implications cannot be determined. We note that this policy is 726 allowed by [RFC7045]. 728 3.5.4. Operational and Interoperability Impact if Blocked 730 As noted in [RFC7045], discarding unknown IPv6 EHs may slow down the 731 deployment of new IPv6 EHs and transport protocols. The 732 corresponding IANA registry ([IANA-PROTOCOLS]) should be monitored 733 such that filtering rules are updated as new IPv6 EHs are 734 standardized. 736 We note that since IPv6 EHs and upper-layer protocols share the same 737 numbering space, discarding unknown IPv6 EHs may result in packets 738 encapsulating unknown upper-layer protocols being discarded. 740 3.5.5. Advice 742 Intermediate systems should discard packets containing unknown IPv6 743 EHs. 745 4. IPv6 Options 747 4.1. General Discussion 749 The following subsections describe specific security implications of 750 different IPv6 options, and provide advice regarding filtering 751 packets that contain such options. 753 4.2. General Security Implications of IPv6 Options 755 The general security implications of IPv6 options are closely related 756 to those discussed in Section 3.2 for IPv6 EHs. Essentially, packets 757 that contain IPv6 options might need to be processed by an IPv6 758 router's general-purpose CPU,and hence could present a DDoS risk to 759 that router's general-purpose CPU (and thus to the router itself). 760 For some architectures, a possible mitigation would be to rate-limit 761 the packets that are to be processed by the general-purpose CPU (see 762 e.g. [Cisco-EH]). 764 4.3. Advice on the Handling of Packets with Specific IPv6 Options 766 The following subsections contain a description of each of the IPv6 767 options that have so far been specified, a summary of the security 768 implications of each of such options, a discussion of possible 769 interoperability implications if packets containing such options are 770 discarded, and specific advice regarding whether packets containing 771 these options should be permitted. 773 4.3.1. Pad1 (Type=0x00) 775 4.3.1.1. Uses 777 This option is used when necessary to align subsequent options and to 778 pad out the containing header to a multiple of 8 octets in length. 780 4.3.1.2. Specification 782 This option is specified in [RFC8200]. 784 4.3.1.3. Specific Security Implications 786 None. 788 4.3.1.4. Operational and Interoperability Impact if Blocked 790 Discarding packets that contain this option would potentially break 791 any protocol that relies on IPv6 EHs. 793 4.3.1.5. Advice 795 Intermediate systems should not discard packets based on the presence 796 of this option. 798 4.3.2. PadN (Type=0x01) 800 4.3.2.1. Uses 802 This option is used when necessary to align subsequent options and to 803 pad out the containing header to a multiple of 8 octets in length. 805 4.3.2.2. Specification 807 This option is specified in [RFC8200]. 809 4.3.2.3. Specific Security Implications 811 Because of the possible size of this option, it could be leveraged as 812 a large-bandwidth covert channel. 814 4.3.2.4. Operational and Interoperability Impact if Blocked 816 Discarding packets that contain this option would potentially break 817 any protocol that relies on IPv6 EHs. 819 4.3.2.5. Advice 821 Intermediate systems should not discard IPv6 packets based on the 822 presence of this option. 824 4.3.3. Jumbo Payload (Type=0XC2) 826 4.3.3.1. Uses 828 The Jumbo payload option provides the means of specifying payloads 829 larger than 65535 bytes. 831 4.3.3.2. Specification 833 This option is specified in [RFC2675]. 835 4.3.3.3. Specific Security Implications 837 There are no specific issues arising from this option, except for 838 improper validity checks of the option and associated packet lengths. 840 4.3.3.4. Operational and Interoperability Impact if Blocked 842 Discarding packets based on the presence of this option will cause 843 IPv6 jumbograms to be discarded. 845 4.3.3.5. Advice 847 Intermediate systems should discard packets that contain this option. 848 An operator should permit this option only in specific scenarios in 849 which support for IPv6 jumbograms is desired. 851 4.3.4. RPL Option (Type=0x63) 853 4.3.4.1. Uses 855 The RPL Option provides a mechanism to include routing information 856 with each datagram that an RPL router forwards. 858 4.3.4.2. Specification 860 This option is specified in [RFC6553]. 862 4.3.4.3. Specific Security Implications 864 Those described in [RFC6553]. 866 4.3.4.4. Operational and Interoperability Impact if Blocked 868 This option is meant to be employed within an RPL instance. As a 869 result, discarding packets based on the presence of this option (e.g. 870 at an ISP) will not result in interoperability implications. 872 4.3.4.5. Advice 874 Non-RPL routers should discard packets that contain an RPL option. 876 4.3.5. Tunnel Encapsulation Limit (Type=0x04) 878 4.3.5.1. Uses 880 The Tunnel Encapsulation Limit option can be employed to specify how 881 many further levels of nesting the packet is permitted to undergo. 883 4.3.5.2. Specification 885 This option is specified in [RFC2473]. 887 4.3.5.3. Specific Security Implications 889 Those described in [RFC2473]. 891 4.3.5.4. Operational and Interoperability Impact if Blocked 893 Discarding packets based on the presence of this option could result 894 in tunnel traffic being discarded. 896 4.3.5.5. Advice 898 Intermediate systems should not discard packets based on the presence 899 of this option. 901 4.3.6. Router Alert (Type=0x05) 903 4.3.6.1. Uses 905 The Router Alert option [RFC2711] is typically employed for the RSVP 906 protocol [RFC2205] and the MLD protocol [RFC2710]. 908 4.3.6.2. Specification 910 This option is specified in [RFC2711]. 912 4.3.6.3. Specific Security Implications 914 Since this option causes the contents of the packet to be inspected 915 by the handling device, this option could be leveraged for performing 916 DoS attacks. 918 4.3.6.4. Operational and Interoperability Impact if Blocked 920 Discarding packets that contain this option would break RSVP and 921 multicast deployments. 923 4.3.6.5. Advice 925 Intermediate systems should discard packets that contain this option. 926 Only in specific environments where support for RSVP, multicast 927 routing, or similar protocols is desired, should this option be 928 permitted. 930 4.3.7. Quick-Start (Type=0x26) 932 4.3.7.1. Uses 934 This IP Option is used in the specification of Quick-Start for TCP 935 and IP, which is an experimental mechanism that allows transport 936 protocols, in cooperation with routers, to determine an allowed 937 sending rate at the start and, at times, in the middle of a data 938 transfer (e.g., after an idle period) [RFC4782]. 940 4.3.7.2. Specification 942 This option is specified in [RFC4782], on the "Experimental" track. 944 4.3.7.3. Specific Security Implications 946 Section 9.6 of [RFC4782] notes that Quick-Start is vulnerable to two 947 kinds of attacks: 949 o attacks to increase the routers' processing and state load, and, 951 o attacks with bogus Quick-Start Requests to temporarily tie up 952 available Quick-Start bandwidth, preventing routers from approving 953 Quick-Start Requests from other connections. 955 We note that if routers in a given environment do not implement and 956 enable the Quick-Start mechanism, only the general security 957 implications of IP options (discussed in Section 4.2) would apply. 959 4.3.7.4. Operational and Interoperability Impact if Blocked 961 The Quick-Start functionality would be disabled, and additional 962 delays in TCP's connection establishment (for example) could be 963 introduced. (Please see Section 4.7.2 of [RFC4782].) We note, 964 however, that Quick-Start has been proposed as a mechanism that could 965 be of use in controlled environments, and not as a mechanism that 966 would be intended or appropriate for ubiquitous deployment in the 967 global Internet [RFC4782]. 969 4.3.7.5. Advice 971 Intermediate systems should not discard IPv6 packets based on the 972 presence of this option. 974 4.3.8. CALIPSO (Type=0x07) 976 4.3.8.1. Uses 978 This option is used for encoding explicit packet Sensitivity Labels 979 on IPv6 packets. It is intended for use only within Multi-Level 980 Secure (MLS) networking environments that are both trusted and 981 trustworthy. 983 4.3.8.2. Specification 985 This option is specified in [RFC5570]. 987 4.3.8.3. Specific Security Implications 989 Presence of this option in a packet does not by itself create any 990 specific new threat. Packets with this option ought not normally be 991 seen on the global public Internet. 993 4.3.8.4. Operational and Interoperability Impact if Blocked 995 If packets with this option are discarded or if the option is 996 stripped from the packet during transmission from source to 997 destination, then the packet itself is likely to be discarded by the 998 receiver because it is not properly labeled. In some cases, the 999 receiver might receive the packet but associate an incorrect 1000 sensitivity label with the received data from the packet whose 1001 CALIPSO was stripped by an intermediate router or firewall. 1002 Associating an incorrect sensitivity label can cause the received 1003 information either to be handled as more sensitive than it really is 1004 ("upgrading") or as less sensitive than it really is ("downgrading"), 1005 either of which is problematic. 1007 4.3.8.5. Advice 1009 Intermediate systems that do not operate in Multi-Level Secure (MLS) 1010 networking environments should discard packets that contain this 1011 option. 1013 4.3.9. SMF_DPD (Type=0x08) 1015 4.3.9.1. Uses 1017 This option is employed in the (experimental) Simplified Multicast 1018 Forwarding (SMF) for unique packet identification for IPv6 I-DPD, and 1019 as a mechanism to guarantee non-collision of hash values for 1020 different packets when H-DPD is used. 1022 4.3.9.2. Specification 1024 This option is specified in [RFC6621]. 1026 4.3.9.3. Specific Security Implications 1028 None. The use of identifiers is subject to the security and privacy 1029 considerations discussed in [I-D.gont-predictable-numeric-ids]. 1031 4.3.9.4. Operational and Interoperability Impact if Blocked 1033 Dropping packets containing this option within a MANET domain would 1034 break SMF. However, dropping such packets at the border of such 1035 domain would have no negative impact. 1037 4.3.9.5. Advice 1039 Intermediate system should discard packets that contain this option. 1041 4.3.10. Home Address (Type=0xC9) 1043 4.3.10.1. Uses 1045 The Home Address option is used by a Mobile IPv6 node while away from 1046 home, to inform the recipient of the mobile node's home address. 1048 4.3.10.2. Specification 1050 This option is specified in [RFC6275]. 1052 4.3.10.3. Specific Security Implications 1054 No (known) additional security implications than those described in 1055 [RFC6275]. 1057 4.3.10.4. Operational and Interoperability Impact if Blocked 1059 Discarding IPv6 packets based on the presence of this option will 1060 break Mobile IPv6. 1062 4.3.10.5. Advice 1064 Intermediate systems should not discard IPv6 packets based on the 1065 presence of this option. 1067 4.3.11. Endpoint Identification (Type=0x8A) 1069 4.3.11.1. Uses 1071 The Endpoint Identification option was meant to be used with the 1072 Nimrod routing architecture [NIMROD-DOC], but has never seen 1073 widespread deployment. 1075 4.3.11.2. Specification 1077 This option is specified in [NIMROD-DOC]. 1079 4.3.11.3. Specific Security Implications 1081 Undetermined. 1083 4.3.11.4. Operational and Interoperability Impact if Blocked 1085 None. 1087 4.3.11.5. Advice 1089 Intermediate systems should discard packets that contain this option. 1091 4.3.12. ILNP Nonce (Type=0x8B) 1093 4.3.12.1. Uses 1095 This option is employed by Identifier-Locator Network Protocol for 1096 IPv6 (ILNPv6) for providing protection against off-path attacks for 1097 packets when ILNPv6 is in use, and as a signal during initial 1098 network-layer session creation that ILNPv6 is proposed for use with 1099 this network-layer session, rather than classic IPv6. 1101 4.3.12.2. Specification 1103 This option is specified in [RFC6744]. 1105 4.3.12.3. Specific Security Implications 1107 Those described in [RFC6744]. 1109 4.3.12.4. Operational and Interoperability Impact if Blocked 1111 Discarding packets that contain this option will break INLPv6 1112 deployments. 1114 4.3.12.5. Advice 1116 Intermediate systems should not discard packets based on the presence 1117 of this option. 1119 4.3.13. Line-Identification Option (Type=0x8C) 1121 4.3.13.1. Uses 1123 This option is used by an Edge Router to identify the subscriber 1124 premises in scenarios where several subscriber premises may be 1125 logically connected to the same interface of an Edge Router. 1127 4.3.13.2. Specification 1129 This option is specified in [RFC6788]. 1131 4.3.13.3. Specific Security Implications 1133 Those described in [RFC6788]. 1135 4.3.13.4. Operational and Interoperability Impact if Blocked 1137 Since this option is meant to be employed in Router Solicitation 1138 messages, discarding packets based on the presence of this option at 1139 intermediate systems will result in no interoperability implications. 1141 4.3.13.5. Advice 1143 Intermediate devices should discard packets that contain this option. 1145 4.3.14. Deprecated (Type=0x4D) 1147 4.3.14.1. Uses 1149 No information has been found about this option type. 1151 4.3.14.2. Specification 1153 No information has been found about this option type. 1155 4.3.14.3. Specific Security Implications 1157 No information has been found about this option type, and hence it 1158 has been impossible to perform the corresponding security assessment. 1160 4.3.14.4. Operational and Interoperability Impact if Blocked 1162 Unknown. 1164 4.3.14.5. Advice 1166 Intermediate systems should discard packets that contain this option. 1168 4.3.15. MPL Option (Type=0x6D) 1170 4.3.15.1. Uses 1172 This option is used with the Multicast Protocol for Low power and 1173 Lossy Networks (MPL), that provides IPv6 multicast forwarding in 1174 constrained networks. 1176 4.3.15.2. Specification 1178 This option is specified in [RFC7731], and is meant to be included 1179 only in Hop-by-Hop Option headers. 1181 4.3.15.3. Specific Security Implications 1183 Those described in [RFC7731]. 1185 4.3.15.4. Operational and Interoperability Impact if Blocked 1187 Dropping packets that contain an MPL option within an MPL network 1188 would break the Multicast Protocol for Low power and Lossy Networks 1189 (MPL). However, dropping such packets at the border of such networks 1190 will have no negative impact. 1192 4.3.15.5. Advice 1194 Intermediate systems should not discard packets based on the presence 1195 of this option. However, since this option has been specified for 1196 the Hop-by-Hop Options, such systems should consider the discussion 1197 in Section 3.4.1. 1199 4.3.16. IP_DFF (Type=0xEE) 1201 4.3.16.1. Uses 1203 This option is employed with the (Experimental) Depth-First 1204 Forwarding (DFF) in Unreliable Networks. 1206 4.3.16.2. Specification 1208 This option is specified in [RFC6971]. 1210 4.3.16.3. Specific Security Implications 1212 Those specified in [RFC6971]. 1214 4.3.16.4. Operational and Interoperability Impact if Blocked 1216 Dropping packets containing this option within a routing domain that 1217 is running DFF would break DFF. However, droping such packets at the 1218 border of such domains will have no security implications. 1220 4.3.16.5. Advice 1222 Intermediate systems that do not operate within a routing domain that 1223 is running DFF should discard packets containing this option. 1225 4.3.17. RFC3692-style Experiment (Types = 0x1E, 0x3E, 0x5E, 0x7E, 0x9E, 1226 0xBE, 0xDE, 0xFE) 1228 4.3.17.1. Uses 1230 These options can be employed for performing RFC3692-style 1231 experiments. It is only appropriate to use these values in 1232 explicitly configured experiments; they must not be shipped as 1233 defaults in implementations. 1235 4.3.17.2. Specification 1237 Specified in RFC 4727 [RFC4727] in the context of RFC3692-style 1238 experiments. 1240 4.3.17.3. Specific Security Implications 1242 The specific security implications will depend on the specific use of 1243 these options. 1245 4.3.17.4. Operational and Interoperability Impact if Blocked 1247 For obvious reasons, discarding packets that contain these options 1248 limits the ability to perform legitimate experiments across IPv6 1249 routers. 1251 4.3.17.5. Advice 1253 Intermediate systems should discard packets that contain these 1254 options. Only in specific environments where RFC3692-style 1255 experiments are meant to be performed should these options be 1256 permitted. 1258 4.4. Advice on the handling of Packets with Unknown IPv6 Options 1260 We refer to IPv6 options that have not been assigned an IPv6 option 1261 type in the corresponding registry ([IANA-IPV6-PARAM]) as "unknown 1262 IPv6 options". 1264 4.4.1. Uses 1266 New IPv6 options may be specified as part of future protocol work. 1268 4.4.2. Specification 1270 The processing of unknown IPv6 options is specified in [RFC8200]. 1272 4.4.3. Specific Security Implications 1274 For obvious reasons, it is impossible to determine specific security 1275 implications of unknown IPv6 options. 1277 4.4.4. Operational and Interoperability Impact if Blocked 1279 Discarding unknown IPv6 options may slow down the deployment of new 1280 IPv6 options. As noted in [draft-gont-6man-ipv6-opt-transmit], the 1281 corresponding IANA registry ([IANA-IPV6-PARAM] should be monitored 1282 such that IPv6 option filtering rules are updated as new IPv6 options 1283 are standardized. 1285 4.4.5. Advice 1287 Enterprise intermediate systems that process the contents of IPv6 EHs 1288 should discard packets that contain unknown options. Other 1289 intermediate systems that process the contents of IPv6 EHs should 1290 permit packets that contain unknown options. 1292 5. IANA Considerations 1294 This document has no actions for IANA. 1296 6. Security Considerations 1298 This document provides advice on the filtering of IPv6 packets that 1299 contain IPv6 EHs (and possibly IPv6 options) at IPv6 transit routers. 1300 It is meant to improve the current situation of widespread dropping 1301 of such IPv6 packets in those cases where the drops result from 1302 improper configuration defaults, or inappropriate advice in this 1303 area. 1305 7. Acknowledgements 1307 The authors of this document would like to thank (in alphabetical 1308 order) Mikael Abrahamsson, Brian Carpenter, Mike Heard, Bob Hinden, 1309 Jen Linkova, Carlos Pignataro, Donald Smith, Ole Troan, Gunter Van De 1310 Velde, and Eric Vyncke, for providing valuable comments on earlier 1311 versions of this document. 1313 This document borrows some text an analysis from [RFC7126], authored 1314 by Fernando Gont, Randall Atkinson, and Carlos Pignataro. 1316 8. References 1318 8.1. Normative References 1320 [draft-gont-6man-ipv6-opt-transmit] 1321 Gont, F., Liu, W., and R. Bonica, "Transmission and 1322 Processing of IPv6 Options", IETF Internet Draft, work in 1323 progress, August 2014. 1325 [RFC1034] Mockapetris, P., "Domain names - concepts and facilities", 1326 STD 13, RFC 1034, DOI 10.17487/RFC1034, November 1987, 1327 . 1329 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1330 Requirement Levels", BCP 14, RFC 2119, 1331 DOI 10.17487/RFC2119, March 1997, 1332 . 1334 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. 1335 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 1336 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, 1337 September 1997, . 1339 [RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1340 (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460, 1341 December 1998, . 1343 [RFC2473] Conta, A. and S. Deering, "Generic Packet Tunneling in 1344 IPv6 Specification", RFC 2473, DOI 10.17487/RFC2473, 1345 December 1998, . 1347 [RFC2675] Borman, D., Deering, S., and R. Hinden, "IPv6 Jumbograms", 1348 RFC 2675, DOI 10.17487/RFC2675, August 1999, 1349 . 1351 [RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast 1352 Listener Discovery (MLD) for IPv6", RFC 2710, 1353 DOI 10.17487/RFC2710, October 1999, 1354 . 1356 [RFC2711] Partridge, C. and A. Jackson, "IPv6 Router Alert Option", 1357 RFC 2711, DOI 10.17487/RFC2711, October 1999, 1358 . 1360 [RFC3692] Narten, T., "Assigning Experimental and Testing Numbers 1361 Considered Useful", BCP 82, RFC 3692, 1362 DOI 10.17487/RFC3692, January 2004, 1363 . 1365 [RFC4302] Kent, S., "IP Authentication Header", RFC 4302, 1366 DOI 10.17487/RFC4302, December 2005, 1367 . 1369 [RFC4303] Kent, S., "IP Encapsulating Security Payload (ESP)", 1370 RFC 4303, DOI 10.17487/RFC4303, December 2005, 1371 . 1373 [RFC4304] Kent, S., "Extended Sequence Number (ESN) Addendum to 1374 IPsec Domain of Interpretation (DOI) for Internet Security 1375 Association and Key Management Protocol (ISAKMP)", 1376 RFC 4304, DOI 10.17487/RFC4304, December 2005, 1377 . 1379 [RFC4727] Fenner, B., "Experimental Values In IPv4, IPv6, ICMPv4, 1380 ICMPv6, UDP, and TCP Headers", RFC 4727, 1381 DOI 10.17487/RFC4727, November 2006, 1382 . 1384 [RFC4782] Floyd, S., Allman, M., Jain, A., and P. Sarolahti, "Quick- 1385 Start for TCP and IP", RFC 4782, DOI 10.17487/RFC4782, 1386 January 2007, . 1388 [RFC5095] Abley, J., Savola, P., and G. Neville-Neil, "Deprecation 1389 of Type 0 Routing Headers in IPv6", RFC 5095, 1390 DOI 10.17487/RFC5095, December 2007, 1391 . 1393 [RFC5201] Moskowitz, R., Nikander, P., Jokela, P., Ed., and T. 1394 Henderson, "Host Identity Protocol", RFC 5201, 1395 DOI 10.17487/RFC5201, April 2008, 1396 . 1398 [RFC5533] Nordmark, E. and M. Bagnulo, "Shim6: Level 3 Multihoming 1399 Shim Protocol for IPv6", RFC 5533, DOI 10.17487/RFC5533, 1400 June 2009, . 1402 [RFC5570] StJohns, M., Atkinson, R., and G. Thomas, "Common 1403 Architecture Label IPv6 Security Option (CALIPSO)", 1404 RFC 5570, DOI 10.17487/RFC5570, July 2009, 1405 . 1407 [RFC6275] Perkins, C., Ed., Johnson, D., and J. Arkko, "Mobility 1408 Support in IPv6", RFC 6275, DOI 10.17487/RFC6275, July 1409 2011, . 1411 [RFC6398] Le Faucheur, F., Ed., "IP Router Alert Considerations and 1412 Usage", BCP 168, RFC 6398, DOI 10.17487/RFC6398, October 1413 2011, . 1415 [RFC6550] Winter, T., Ed., Thubert, P., Ed., Brandt, A., Hui, J., 1416 Kelsey, R., Levis, P., Pister, K., Struik, R., Vasseur, 1417 JP., and R. Alexander, "RPL: IPv6 Routing Protocol for 1418 Low-Power and Lossy Networks", RFC 6550, 1419 DOI 10.17487/RFC6550, March 2012, 1420 . 1422 [RFC6553] Hui, J. and JP. Vasseur, "The Routing Protocol for Low- 1423 Power and Lossy Networks (RPL) Option for Carrying RPL 1424 Information in Data-Plane Datagrams", RFC 6553, 1425 DOI 10.17487/RFC6553, March 2012, 1426 . 1428 [RFC6554] Hui, J., Vasseur, JP., Culler, D., and V. Manral, "An IPv6 1429 Routing Header for Source Routes with the Routing Protocol 1430 for Low-Power and Lossy Networks (RPL)", RFC 6554, 1431 DOI 10.17487/RFC6554, March 2012, 1432 . 1434 [RFC6621] Macker, J., Ed., "Simplified Multicast Forwarding", 1435 RFC 6621, DOI 10.17487/RFC6621, May 2012, 1436 . 1438 [RFC6740] Atkinson, RJ. and SN. Bhatti, "Identifier-Locator Network 1439 Protocol (ILNP) Architectural Description", RFC 6740, 1440 DOI 10.17487/RFC6740, November 2012, 1441 . 1443 [RFC6744] Atkinson, RJ. and SN. Bhatti, "IPv6 Nonce Destination 1444 Option for the Identifier-Locator Network Protocol for 1445 IPv6 (ILNPv6)", RFC 6744, DOI 10.17487/RFC6744, November 1446 2012, . 1448 [RFC6788] Krishnan, S., Kavanagh, A., Varga, B., Ooghe, S., and E. 1449 Nordmark, "The Line-Identification Option", RFC 6788, 1450 DOI 10.17487/RFC6788, November 2012, 1451 . 1453 [RFC6971] Herberg, U., Ed., Cardenas, A., Iwao, T., Dow, M., and S. 1454 Cespedes, "Depth-First Forwarding (DFF) in Unreliable 1455 Networks", RFC 6971, DOI 10.17487/RFC6971, June 2013, 1456 . 1458 [RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing 1459 of IPv6 Extension Headers", RFC 7045, 1460 DOI 10.17487/RFC7045, December 2013, 1461 . 1463 [RFC7112] Gont, F., Manral, V., and R. Bonica, "Implications of 1464 Oversized IPv6 Header Chains", RFC 7112, 1465 DOI 10.17487/RFC7112, January 2014, 1466 . 1468 [RFC7731] Hui, J. and R. Kelsey, "Multicast Protocol for Low-Power 1469 and Lossy Networks (MPL)", RFC 7731, DOI 10.17487/RFC7731, 1470 February 2016, . 1472 [RFC8200] Deering, S. and R. Hinden, "Internet Protocol, Version 6 1473 (IPv6) Specification", STD 86, RFC 8200, 1474 DOI 10.17487/RFC8200, July 2017, 1475 . 1477 8.2. Informative References 1479 [Biondi2007] 1480 Biondi, P. and A. Ebalard, "IPv6 Routing Header Security", 1481 CanSecWest 2007 Security Conference, 2007, 1482 . 1484 [Cisco-EH] 1485 Cisco Systems, "IPv6 Extension Headers Review and 1486 Considerations", Whitepaper. October 2006, 1487 . 1490 [draft-ietf-nimrod-eid] 1491 Lynn, C., "Endpoint Identifier Destination Option", IETF 1492 Internet Draft, draft-ietf-nimrod-eid-00.txt, November 1493 1995. 1495 [FW-Benchmark] 1496 Zack, E., "Firewall Security Assessment and Benchmarking 1497 IPv6 Firewall Load Tests", IPv6 Hackers Meeting #1, 1498 Berlin, Germany. June 30, 2013, 1499 . 1503 [I-D.gont-predictable-numeric-ids] 1504 Gont, F. and I. Arce, "Security and Privacy Implications 1505 of Numeric Identifiers Employed in Network Protocols", 1506 draft-gont-predictable-numeric-ids-01 (work in progress), 1507 July 2017. 1509 [I-D.gont-v6ops-ipv6-ehs-packet-drops] 1510 Gont, F., Hilliard, N., Doering, G., (Will), S., and W. 1511 Kumari, "Operational Implications of IPv6 Packets with 1512 Extension Headers", draft-gont-v6ops-ipv6-ehs-packet- 1513 drops-03 (work in progress), March 2016. 1515 [I-D.ietf-6man-hbh-header-handling] 1516 Baker, F. and R. Bonica, "IPv6 Hop-by-Hop Options 1517 Extension Header", draft-ietf-6man-hbh-header-handling-03 1518 (work in progress), March 2016. 1520 [IANA-IPV6-PARAM] 1521 Internet Assigned Numbers Authority, "Internet Protocol 1522 Version 6 (IPv6) Parameters", December 2013, 1523 . 1526 [IANA-PROTOCOLS] 1527 Internet Assigned Numbers Authority, "Protocol Numbers", 1528 2014, . 1531 [NIMROD-DOC] 1532 Nimrod Documentation Page, 1533 "http://ana-3.lcs.mit.edu/~jnc/nimrod/". 1535 [RFC3871] Jones, G., Ed., "Operational Security Requirements for 1536 Large Internet Service Provider (ISP) IP Network 1537 Infrastructure", RFC 3871, DOI 10.17487/RFC3871, September 1538 2004, . 1540 [RFC6192] Dugal, D., Pignataro, C., and R. Dunn, "Protecting the 1541 Router Control Plane", RFC 6192, DOI 10.17487/RFC6192, 1542 March 2011, . 1544 [RFC7126] Gont, F., Atkinson, R., and C. Pignataro, "Recommendations 1545 on Filtering of IPv4 Packets Containing IPv4 Options", 1546 BCP 186, RFC 7126, DOI 10.17487/RFC7126, February 2014, 1547 . 1549 [RFC7739] Gont, F., "Security Implications of Predictable Fragment 1550 Identification Values", RFC 7739, DOI 10.17487/RFC7739, 1551 February 2016, . 1553 [RFC7872] Gont, F., Linkova, J., Chown, T., and W. Liu, 1554 "Observations on the Dropping of Packets with IPv6 1555 Extension Headers in the Real World", RFC 7872, 1556 DOI 10.17487/RFC7872, June 2016, 1557 . 1559 Authors' Addresses 1561 Fernando Gont 1562 UTN-FRH / SI6 Networks 1563 Evaristo Carriego 2644 1564 Haedo, Provincia de Buenos Aires 1706 1565 Argentina 1567 Phone: +54 11 4650 8472 1568 Email: fgont@si6networks.com 1569 URI: http://www.si6networks.com 1570 Will(Shucheng) Liu 1571 Huawei Technologies 1572 Bantian, Longgang District 1573 Shenzhen 518129 1574 P.R. China 1576 Email: liushucheng@huawei.com 1578 Ronald P. Bonica 1579 Juniper Networks 1580 2251 Corporate Park Drive 1581 Herndon, VA 20171 1582 US 1584 Phone: 571 250 5819 1585 Email: rbonica@juniper.net