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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 DOTS T. Reddy 3 Internet-Draft McAfee 4 Intended status: Standards Track M. Boucadair 5 Expires: October 28, 2019 Orange 6 J. Shallow 7 April 26, 2019 9 Distributed Denial-of-Service Open Threat Signaling (DOTS) Signal 10 Channel Call Home 11 draft-ietf-dots-signal-call-home-01 13 Abstract 15 This document specifies the DOTS signal channel Call Home service, 16 which enables a DOTS server to initiate a secure connection to a DOTS 17 client, and to receive the attack traffic information from the DOTS 18 client. The DOTS server in turn uses the attack traffic information 19 to identify the compromised devices launching the outgoing DDoS 20 attack and takes appropriate mitigation action(s). 22 The Call Home service is not specific to the home networks; the 23 solution targets any deployment which requires to block DDoS attack 24 traffic closer to the source(s) of a DDoS attack. 26 Status of This Memo 28 This Internet-Draft is submitted in full conformance with the 29 provisions of BCP 78 and BCP 79. 31 Internet-Drafts are working documents of the Internet Engineering 32 Task Force (IETF). Note that other groups may also distribute 33 working documents as Internet-Drafts. The list of current Internet- 34 Drafts is at https://datatracker.ietf.org/drafts/current/. 36 Internet-Drafts are draft documents valid for a maximum of six months 37 and may be updated, replaced, or obsoleted by other documents at any 38 time. It is inappropriate to use Internet-Drafts as reference 39 material or to cite them other than as "work in progress." 41 This Internet-Draft will expire on October 28, 2019. 43 Copyright Notice 45 Copyright (c) 2019 IETF Trust and the persons identified as the 46 document authors. All rights reserved. 48 This document is subject to BCP 78 and the IETF Trust's Legal 49 Provisions Relating to IETF Documents 50 (https://trustee.ietf.org/license-info) in effect on the date of 51 publication of this document. Please review these documents 52 carefully, as they describe your rights and restrictions with respect 53 to this document. Code Components extracted from this document must 54 include Simplified BSD License text as described in Section 4.e of 55 the Trust Legal Provisions and are provided without warranty as 56 described in the Simplified BSD License. 58 Table of Contents 60 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 61 1.1. The Problem . . . . . . . . . . . . . . . . . . . . . . . 2 62 1.2. The Solution . . . . . . . . . . . . . . . . . . . . . . 4 63 1.3. Applicability Scope . . . . . . . . . . . . . . . . . . . 5 64 2. Notational Conventions and Terminology . . . . . . . . . . . 7 65 3. DOTS Signal Channel Call Home . . . . . . . . . . . . . . . . 7 66 3.1. Procedure . . . . . . . . . . . . . . . . . . . . . . . . 7 67 3.2. DOTS Signal Channel Extension . . . . . . . . . . . . . . 8 68 3.2.1. Mitigation Request . . . . . . . . . . . . . . . . . 8 69 3.2.2. DOTS Signal Call Home YANG Module . . . . . . . . . . 12 70 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 16 71 4.1. DOTS Signal Channel Call Home UDP and TCP Port Number . . 16 72 4.2. DOTS Signal Channel CBOR Mappings Registry . . . . . . . 16 73 4.3. New DOTS Conflict Cause . . . . . . . . . . . . . . . . . 16 74 4.4. DOTS Signal Call Home YANG Module . . . . . . . . . . . . 17 75 5. Security Considerations . . . . . . . . . . . . . . . . . . . 17 76 6. Privacy Considerations . . . . . . . . . . . . . . . . . . . 18 77 7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 19 78 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 19 79 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 19 80 9.1. Normative References . . . . . . . . . . . . . . . . . . 19 81 9.2. Informative References . . . . . . . . . . . . . . . . . 20 82 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 22 84 1. Introduction 86 1.1. The Problem 88 The DOTS signal channel protocol [I-D.ietf-dots-signal-channel] is 89 used to carry information about a network resource or a network (or a 90 part thereof) that is under a Distributed Denial of Service (DDoS) 91 attack. Such information is sent by a DOTS client to one or multiple 92 DOTS servers so that appropriate mitigation actions are undertaken on 93 traffic deemed suspicious. Various use cases are discussed in 94 [I-D.ietf-dots-use-cases]. 96 Internet of Things (IoT) devices are becoming more and more prevalent 97 in home networks, and with compute and memory becoming cheaper and 98 cheaper, various types of IoT devices become available in the 99 consumer market at affordable price. But on the downside, the main 100 threat being most of these IoT devices are bought off-the-shelf and 101 most manufacturers haven't considered security in the product design. 102 IoT devices deployed in home networks can be easily compromised, they 103 do not have an easy mechanism to upgrade, and IoT manufactures may 104 cease manufacture and/or discontinue patching vulnerabilities on IoT 105 devices (Sections 5.4 and 5.5 of [I-D.irtf-t2trg-iot-seccons]). 106 However, these vulnerable and compromised devices will continue to be 107 used for a long period of time in the home, and the end-user does not 108 know that IoT devices in his/her home are compromised. The 109 compromised IoT devices are typically used for launching DDoS attacks 110 (Section 3 of [I-D.irtf-t2trg-iot-seccons]) on victims while the 111 owner/administrator of the home network is not aware about such 112 misbehaviors. Similar to other DDoS attacks, the victim in this 113 attack can be an application server, a host, a router, a firewall, or 114 an entire network. 116 Nowadays, network devices in a home network offer network security 117 (e.g., firewall or Intrusion Protection System (IPS) service on a 118 home router) to protect the devices connected to the home network 119 from both external and internal attacks. Over the years several 120 techniques have been identified to detect DDoS attacks, some of these 121 techniques can be enabled on home network devices but most of them 122 are used in the Internet Service Provider (ISP)'s network. The ISP 123 offering DDoS mitigation service can detect outgoing DDoS attack 124 traffic originating from its subscribers or the ISP may receive 125 filtering rules (e.g., using BGP flowspec [RFC5575]) from a 126 downstream service provider to filter, block, or rate-limit DDoS 127 attack traffic originating from the ISP's subscribers to a downstream 128 target. 130 Some of the DDoS attacks like spoofed RST or FIN packets, Slowloris, 131 and Transport Layer Security (TLS) re-negotiation are difficult to 132 detect on a home network device without adversely affecting its 133 performance. The reason is typically home devices such as home 134 routers have fast path to boost the throughput. For every new TCP/ 135 UDP flow, only the first few packets are punted through the slow 136 path. Hence, it is not possible to detect various DDoS attacks in 137 the slow path, since the attack payload is sent to the target server 138 after the flow is switched to fast path. Deep Packet Inspection 139 (DPI) of all the packets of a flow would be able to detect some of 140 the attacks. However, a full-fledged DPI to detect these type of 141 DDoS attacks is functionally or operationally not possible for all 142 the devices attached to the home network owing to the memory and CPU 143 limitations of the home routers. Further, for certain DDoS attacks 144 the ability to distinguish legitimate traffic from attacker traffic 145 on a per packet basis is complex. This complexity is due to that the 146 packet itself may look "legitimate" and no attack signature can be 147 identified. The anomaly can be identified only after detailed 148 statistical analysis. 150 The ISP on the other hand can detect some DDoS attacks originating 151 from a home network (e.g., Section 2.6 of [RFC8517]), but the ISP 152 does not have a mechanism to detect which device in the home network 153 is generating the DDoS attack traffic. The primary reason being that 154 devices in an IPv4 home network are typically behind a Network 155 Address Translation (NAT) border. Even in case of a IPv6 home 156 network, although the ISP can identify the infected device in the 157 home network launching the DDoS traffic by tracking its unique IPv6 158 address, the infected device can easily change its IPv6 address to 159 evade remediation. 161 Existing approaches are still suffering from misused access network 162 resources by abusing devices; the support of means for blocking such 163 attacks close to the sources are missing. In particular, the DOTS 164 signal protocol does not discuss cooperative DDoS mitigation between 165 the network hosting an attack source and the ISP to the suppress the 166 outbound DDoS attack traffic originating from that network. 168 1.2. The Solution 170 This specification addresses the problems discussed in Section 1.1 171 and presents the DOTS signal channel Call Home extension, which 172 enables the DOTS server to initiate a secure connection to the DOTS 173 client, and the DOTS client then conveys the attack traffic 174 information to the DOTS server. 176 A DOTS client relies upon a variety of triggers to make use of the 177 Call Home function (e.g., scrubbing the traffic from the attack 178 source, receiving an alert from an attack target, a peer DDoS 179 Mitigation System (DMS), or a transit provider). The definition of 180 these triggers is deployment-specific. It is therefore out of the 181 scope of this document to elaborate on how these triggers are made 182 available to a DOTS client. 184 In a typical deployment scenario, the DOTS server is enabled on a 185 Customer Premises Equipment (CPE), which is aligned with recent 186 trends to enrich the CPE with advanced security features. Unlike 187 classic DOTS deployments [I-D.ietf-dots-use-cases], such DOTS server 188 maintains a single DOTS signal channel session for each DOTS-capable 189 upstream provisioning domain [I-D.ietf-dots-multihoming]. 191 For instance, the DOTS server in the home network initiates the Call 192 Home in 'idle' time and then subsequently the DOTS client in the ISP 193 environment can initiate a mitigation request whenever the ISP 194 detects there is an attack from a compromised device in the DOTS 195 server domain (i.e., from within the home network). 197 The DOTS server uses the DDoS attack traffic information to identify 198 the compromised device in its domain that is responsible for 199 launching the DDoS attack, optionally notifies a network 200 administrator, and takes appropriate mitigation action(s). A 201 mitigation action can be to quarantine the compromised device or 202 block its traffic to the attack target(s) until the mitigation 203 request is withdrawn. 205 Other motivations for introducing the Call Home function are 206 discussed in Section 1.1 of [RFC8071]. 208 This document assumes that DOTS servers are provisioned with a way to 209 know how to reach the upstream DOTS client(s), which could occur by a 210 variety of means (e.g., [I-D.ietf-dots-server-discovery]). The 211 specification of such means are out of scope of this document. 213 1.3. Applicability Scope 215 The aforementioned problems may be encountered in other deployments 216 than those discussed in Section 1.1 (e.g., data centers, enterprise 217 networks). The solution specified in this document can be used for 218 those deployments to block DDoS attack traffic closer to the 219 source(s) of the attack. The Call Home reference architecture is 220 shown in Figure 1. 222 +-------------+ 223 |Attack Target| 224 +-----+-------+ 225 | /\ 226 | || Target Network 227 ......................|.||.................... 228 | || 229 .--------+-||-------. 230 ( || )-. 231 .' || ' 232 ( Internet || ) 233 ( || -' 234 '-( || ) 235 '------+-||---------' 236 ......................|.||..................... 237 | || Network Provider 238 | || (DMS) 239 .--------+-||-------. 240 ( || )-. 241 .' DOTS || ' 242 ( client || ) 243 ( || -' 244 '-( || ) 245 '------+-||---------' 246 | || 247 ......................|.||....................... 248 | || Source Network 249 .--------+-||-------. 250 ( || )-. 251 .' DOTS || ' 252 ( server || Outbound ) 253 ( || DDoS -' 254 '-( || Attack ) 255 '------+-||---------' 256 | || 257 +-----+-++----+ 258 |Attack Source| 259 +-------------+ 261 Figure 1: Call Home Reference Architecture 263 It is out of the scope of this document to identify an exhaustive 264 list of such deployments. 266 2. Notational Conventions and Terminology 268 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 269 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 270 "OPTIONAL" in this document are to be interpreted as described in BCP 271 14 [RFC2119][RFC8174] when, and only when, they appear in all 272 capitals, as shown here. 274 The reader should be familiar with the terms defined in 275 [I-D.ietf-dots-requirements]. 277 The meaning of the symbols in YANG tree diagrams is defined in 278 [RFC8340]. 280 (D)TLS is used for statements that apply to both Transport Layer 281 Security (TLS) [RFC8446] and Datagram Transport Layer Security (DTLS) 282 [RFC6347]. Specific terms are used for any statement that applies to 283 either protocol alone. 285 3. DOTS Signal Channel Call Home 287 3.1. Procedure 289 The DOTS signal channel Call Home extension preserves all but one of 290 the DOTS client/server roles in the DOTS protocol stack, as compared 291 to DOTS client-initiated DOTS signal channel protocol 292 [I-D.ietf-dots-signal-channel]. The role reversal that occurs is at 293 the (D)TLS layer; that is, (1) the DOTS server acts as a DTLS client 294 and the DOTS client acts as a DTLS server or (2) the DOTS server acts 295 as a TLS client initiating the underlying TCP connection and the DOTS 296 client acts as a TLS server. The DOTS server initiates (D)TLS 297 handshake to the DOTS client. 299 For example, a home network element (e.g., home router) co-located 300 with a DOTS server (likely, a client-domain DOTS gateway) is the 301 (D)TLS server. However, when calling home, the DOTS server initially 302 assumes the role of the (D)TLS client, but the network element's role 303 as a DOTS server remains the same. Furthermore, existing certificate 304 chains and mutual authentication mechanisms between the DOTS agents 305 are unaffected by the Call Home function. This Call Home function 306 enables the DOTS server co-located with a network element (possibly 307 behind NATs and firewalls) reachable by only the intended DOTS client 308 and hence the DOTS server cannot be subjected to DDoS attacks. 310 Figure 2 illustrates a sample Call Home flow exchange: 312 +--------+ +--------+ 313 | DOTS | | DOTS | 314 | server | | client | 315 +---+----+ +----+---+ 316 | | 317 | 1. (D)TLS connection | 318 |----------------------------------->| 319 | 2. Mitigation request | 320 |<-----------------------------------| 321 | ... | 323 Figure 2: DOTS Signal Channel Call Home Sequence Diagram 325 The DOTS signal channel Call Home procedure is as follows: 327 1. If UDP transport is used, the DOTS server begins by initiating a 328 DTLS connection to the DOTS client. The DOTS client MUST support 329 accepting DTLS connection on the IANA-assigned port number 330 defined in Section 4.1, but MAY be configured to listen to a 331 different port number. 333 If TCP is used, the DOTS server begins by initiating a TCP 334 connection to the DOTS client. The DOTS client MUST support 335 accepting TCP connections on the IANA-assigned port number 336 defined in Section 4.1, but MAY be configured to listen to a 337 different port number. Using this TCP connection, the DOTS 338 server initiates a TLS connection to the DOTS client. 340 The Happy Eyeballs mechanism explained in Section 4.3 of 341 [I-D.ietf-dots-signal-channel] can be used for initiating (D)TLS 342 connections. 344 2. Using this (D)TLS connection, the DOTS client may request, 345 withdraw, or retrieve the status of mitigation requests. 347 3.2. DOTS Signal Channel Extension 349 3.2.1. Mitigation Request 351 This specification extends the mitigation request defined in 352 Section 4.4.1 of [I-D.ietf-dots-signal-channel] to convey the 353 attacker source prefixes and source port numbers. The DOTS client 354 conveys the following new parameters in the CBOR body of the 355 mitigation request: 357 source-prefix: A list of attacker prefixes used to attack the 358 target. Prefixes are represented using Classless Inter-Domain 359 Routing (CIDR) notation [RFC4632]. 361 As a reminder, the prefix length MUST be less than or equal to 32 362 (resp. 128) for IPv4 (resp. IPv6). 364 The prefix list MUST NOT include broadcast, loopback, or multicast 365 addresses. These addresses are considered as invalid values. In 366 addition, the DOTS client MUST validate that attacker prefixes are 367 within the scope of the DOTS server domain. 369 This is an optional attribute. 371 source-port-range: A list of port numbers used by the attack traffic 372 flows. 374 A port range is defined by two bounds, a lower port number (lower- 375 port) and an upper port number (upper-port). When only 'lower- 376 port' is present, it represents a single port number. 378 For TCP, UDP, Stream Control Transmission Protocol (SCTP) 379 [RFC4960], or Datagram Congestion Control Protocol (DCCP) 380 [RFC4340], a range of ports can be, for example, 0-1023, 381 1024-65535, or 1024-49151. 383 This is an optional attribute. 385 source-icmp-type: A list of ICMP types used by the attack traffic 386 flows. An ICMP type range is defined by two bounds, a lower ICMP 387 type (lower-type) and an upper ICMP type (upper-type). When only 388 'lower-type' is present, it represents a single ICMP type. 390 This is an optional attribute. 392 The 'source-prefix' parameter is a mandatory attribute when the 393 attack traffic information is signaled by a DOTS client in the Call 394 Home scenario. The 'target-uri' or 'target-fqdn' parameters can be 395 included in a mitigation request for diagnostic purposes to notify 396 the DOTS server domain administrator, but SHOULD NOT be used to 397 determine the target IP addresses. Note that 'target-prefix' becomes 398 a mandatory attribute in the mitigation request signaling the attack 399 information because 'target-uri' and 'target-fqdn' are optional 400 attributes and 'alias-name' will not be conveyed in a mitigation 401 request. 403 In order to help attack source identification by a DOTS server, the 404 DOTS client SHOULD include in its mitigation request additional 405 information such as 'source-port-range' or 'source-icmp-type-range'. 406 The DOTS client may not include such information if 'source-prefix' 407 conveys an IPv6 address/prefix. 409 If a Carrier Grade NAT (CGN, including NAT64) is located between the 410 DOTS client domain and DOTS server domain, communicating an external 411 IP address in a mitigation request is likely to be discarded by the 412 DOTS server because the external IP address is not visible locally to 413 the DOTS server (see Figure 3). The DOTS server is only aware of the 414 internal IP addresses/prefixes bound to its domain. Thus, the DOTS 415 client MUST NOT include the external IP address and/or port number 416 identifying the suspect attack source, but MUST include the internal 417 IP address and/or port number. To that aim, the DOTS client SHOULD 418 rely on mechanisms, such as [RFC8512] or [RFC8513], to retrieve the 419 internal IP address and port number which are mapped to an external 420 IP address and port number. 422 N | .-------------------. 423 E | ( )-. 424 T | .' ' 425 W | ( ) 426 O | ( DOTS server -' 427 R | '-( ) 428 K | '-------+-----------' 429 | | 430 P | | 431 R | +---+---+ 432 O | | CGN | External Realm 433 V |..............|.......|...................... 434 I | | | Internel Realm 435 D | +---+---+ 436 E | | 437 R | | 438 --- | 439 .---------+---------. 440 ( )-. 441 .' Source Network ' 442 ( ) 443 ( DOTS client -' 444 '-( ) 445 '------+------------' 446 | 447 +-----+-------+ 448 |Attack Source| 449 +-------------+ 451 Figure 3: Example of a CGN Between DOTS Domains 453 If a MAP Border Relay [RFC7597] or lwAFTR [RFC7596] is enabled in the 454 provider's domain to service its customers, the identification of an 455 attack source bound to an IPv4 address/prefix MUST also rely on 456 source port numbers because the same IPv4 address is assigned to 457 multiple customers. The port information is required to 458 unambiguously identify the source of an attack. 460 The DOTS server MUST check that the 'source-prefix' is within the 461 scope of the DOTS server domain in the Call Home scenario. Note that 462 in such scenario, the DOTS server considers, by default, that any 463 routeable IP prefix enclosed in 'target-prefix' is within the scope 464 of the DOTS client. Invalid mitigation requests are handled as per 465 Section 4.4.1 of [I-D.ietf-dots-signal-channel]. 467 If a translator is enabled on the boundaries of the domain hosting 468 the DOTS server (a CPE with NAT enabled as shown in Figure 4, 469 typically), the DOTS server uses the attack traffic information 470 conveyed in a mitigation request to find the internal source IP 471 address of the compromised device and blocks the traffic from the 472 compromised device traffic to the attack target until the mitigation 473 request is withdrawn. Doing so allows to isolate the suspicious 474 device while avoiding to disturb other services. 476 .-------------------. 477 ( )-. 478 .' Network Provider ' 479 ( (DMS) ) 480 ( DOTS server -' 481 '-( ) 482 '------+------------' 483 | 484 | 485 --- +--+----+ 486 S | | CPE | External Realm 487 O |..............|.......|................ 488 U | | NAT | Internel Realm 489 R | +-------+ 490 C | | 491 E | .--------+----------. 492 | ( )-. 493 N | .' ' 494 E | ( ) 495 T | ( DOTS client -' 496 W | '-( ) 497 O | '------+------------' 498 R | | 499 K | +-----+-------+ 500 | |Attack Source| 501 +-------------+ 503 Figure 4: Example of a DOTS Client Domain with a NAT Embeded in a CPE 504 The DOTS server domain administrator consent MAY be required to block 505 the traffic from the compromised device to the attack target. An 506 implementation MAY have a configuration knob to block the traffic 507 from the compromised device to the attack target with or without DOTS 508 server domain administrator consent. If the attack traffic is 509 blocked, the DOTS server informs the DOTS client that the attack is 510 being mitigated. 512 If the attack traffic information is identified by the DOTS server or 513 the DOTS server domain administrator as legitimate traffic, the 514 mitigation request is rejected, and 4.09 (Conflict) is returned to 515 the DOTS client. The conflict-clause (defined in Section 4.4.1 of 516 [I-D.ietf-dots-signal-channel]) indicates the cause of the conflict. 517 The following new value is defined: 519 4: Mitigation request rejected. This code is returned by the DOTS 520 server to indicate the attack traffic has been classified as 521 legitimate traffic. 523 Once the request is validated by the DOTS server, appropriate actions 524 are enforced to block the attack traffic within the source network. 525 The DOTS client is informed about the progress of the attack 526 mitigation following the rules in [I-D.ietf-dots-signal-channel]. 527 For example, if the DOTS server is embedded in a CPE, it can program 528 the packet processor to punt all the traffic from the compromised 529 device to the target to slow path. The CPE inspects the punted slow 530 path traffic to detect and block the outgoing DDoS attack traffic or 531 quarantine the device (e.g., using MAC level filtering) until it is 532 remediated, and notifies the CPE administrator about the compromised 533 device. 535 3.2.2. DOTS Signal Call Home YANG Module 537 3.2.2.1. Tree Structure 539 This document augments the "dots-signal-channel" DOTS signal YANG 540 module defined in [I-D.ietf-dots-signal-channel] for signaling the 541 attack traffic information. This document defines the YANG module 542 "ietf-dots-call-home", which has the following tree structure: 544 module: ietf-dots-call-home 545 augment /ietf-signal:dots-signal/ietf-signal:message-type 546 /ietf-signal:mitigation-scope/ietf-signal:scope: 547 +--rw source-prefix* inet:ip-prefix {source-signaling}? 548 +--rw source-port-range* [lower-port] {source-signaling}? 549 | +--rw lower-port inet:port-number 550 | +--rw upper-port? inet:port-number 551 +--rw source-icmp-type-range* 552 | [lower-type] {source-signaling}? 553 +--rw lower-type uint8 554 +--rw upper-type? uint8 556 3.2.2.2. YANG Module 558 This module uses the common YANG types defined in [RFC6991]. 560 file "ietf-dots-call-home@2019-04-25.yang" 562 module ietf-dots-call-home { 563 yang-version 1.1; 564 namespace "urn:ietf:params:xml:ns:yang:ietf-dots-call-home"; 565 prefix call-home; 567 import ietf-inet-types { 568 prefix inet; 569 reference 570 "Section 4 of RFC 6991"; 571 } 572 import ietf-dots-signal-channel { 573 prefix ietf-signal; 574 reference 575 "RFC YYYY: Distributed Denial-of-Service Open Threat 576 Signaling (DOTS) Signal Channel Specification"; 577 } 579 organization 580 "IETF DDoS Open Threat Signaling (DOTS) Working Group"; 581 contact 582 "WG Web: 583 WG List: 585 Editor: Konda, Tirumaleswar Reddy 586 ; 588 Editor: Mohamed Boucadair 589 ; 591 Editor: Jon Shallow 592 "; 594 description 595 "This module contains YANG definitions for the signaling 596 messages exchanged between a DOTS client and a DOTS server 597 for the Call Home deployment scenario. 599 Copyright (c) 2019 IETF Trust and the persons identified as 600 authors of the code. All rights reserved. 602 Redistribution and use in source and binary forms, with or 603 without modification, is permitted pursuant to, and subject 604 to the license terms contained in, the Simplified BSD License 605 set forth in Section 4.c of the IETF Trust's Legal Provisions 606 Relating to IETF Documents 607 (http://trustee.ietf.org/license-info). 609 This version of this YANG module is part of RFC XXXX; see 610 the RFC itself for full legal notices."; 612 revision 2019-04-25 { 613 description 614 "Initial revision."; 615 reference 616 "RFC XXXX: Distributed Denial-of-Service Open Threat 617 Signaling (DOTS) Signal Channel Call Home"; 618 } 620 feature source-signaling { 621 description 622 "This feature means that source-related information 623 can be supplied in mitigation requests."; 624 } 626 augment "/ietf-signal:dots-signal/ietf-signal:message-type/" 627 + "ietf-signal:mitigation-scope/ietf-signal:scope" { 628 if-feature source-signaling; 629 description "Attacker source details."; 631 leaf-list source-prefix { 632 type inet:ip-prefix; 633 description 634 "IPv4 or IPv6 prefix identifying the attacker(s)."; 635 } 636 list source-port-range { 637 key "lower-port"; 638 description 639 "Port range. When only lower-port is 640 present, it represents a single port number."; 641 leaf lower-port { 642 type inet:port-number; 643 mandatory true; 644 description 645 "Lower port number of the port range."; 646 } 647 leaf upper-port { 648 type inet:port-number; 649 must ". >= ../lower-port" { 650 error-message 651 "The upper port number must be greater than 652 or equal to lower port number."; 653 } 654 description 655 "Upper port number of the port range."; 656 } 657 } 658 list source-icmp-type-range { 659 key "lower-type"; 660 description 661 "ICMP type range. When only lower-type is 662 present, it represents a single ICMP type."; 663 leaf lower-type { 664 type uint8; 665 mandatory true; 666 description 667 "Lower ICMP type of the ICMP type range."; 668 } 669 leaf upper-type { 670 type uint8; 671 must ". >= ../lower-type" { 672 error-message 673 "The upper ICMP type must be greater than 674 or equal to lower ICMP type."; 675 } 676 description 677 "Upper type of the ICMP type range."; 678 } 679 } 680 } 681 } 682 684 4. IANA Considerations 686 4.1. DOTS Signal Channel Call Home UDP and TCP Port Number 688 IANA is requested to assign the port number TBD to the DOTS signal 689 channel Call Home protocol for both UDP and TCP from the "Service 690 Name and Transport Protocol Port Number Registry" available at: 691 https://www.iana.org/assignments/service-names-port-numbers/service- 692 names-port-numbers.xhtml. 694 The assignment of port number 4647 is strongly suggested (DOTS signal 695 channel uses port number 4646). 697 4.2. DOTS Signal Channel CBOR Mappings Registry 699 This specification registers the 'source-prefix' and 'source-port- 700 range' parameters in the IANA "DOTS Signal Channel CBOR Mappings" 701 registry established by [I-D.ietf-dots-signal-channel]. 703 The 'source-prefix', 'source-port-range', and 'source-icmp-type- 704 range' are comprehension-optional parameters. 706 o Note to the RFC Editor: Please delete (TBD1)-(TBD5) once CBOR keys 707 are assigned from the 0x8000 - 0xBFFF range. 709 +-------------------+------------+--------+---------------+--------+ 710 | Parameter Name | YANG | CBOR | CBOR Major | JSON | 711 | | Type | Key | Type & | Type | 712 | | | | Information | | 713 +-------------------+------------+--------+---------------+--------+ 714 | source-prefix | leaf-list | 0x8000 | 4 array | Array | 715 | | inet: | (TBD1) | | | 716 | | ip-prefix | | 3 text string | String | 717 | source-port-range | list | 0x8001 | 4 array | Array | 718 | | | (TBD2) | | | 719 | source-icmp-type- | list | 0x8002 | 4 array | Array | 720 | range | | (TBD3) | | | 721 | lower-type | uint8 | 0x8003 | 0 unsigned | Number | 722 | | | (TBD4) | | | 723 | upper-type | uint8 | 0x8004 | 0 unsigned | Number | 724 | | | (TBD5) | | | 725 +-------------------+------------+--------+---------------+--------+ 727 4.3. New DOTS Conflict Cause 729 This document requests IANA to assign a new code from the "DOTS 730 Conflict Cause Codes" registry: 732 +------+------------------+-----------------------------+-----------+ 733 | Code | Label | Description | Reference | 734 +------+------------------+-----------------------------+-----------+ 735 | 4 | request-rejected | Mitigation request | [RFCXXXX] | 736 | | | rejected. This code is | | 737 | | | returned by the DOTS server | | 738 | | | to indicate the attack | | 739 | | | traffic has been classified | | 740 | | | as legitimate traffic. | | 741 +------+------------------+-----------------------------+-----------+ 743 4.4. DOTS Signal Call Home YANG Module 745 This document requests IANA to register the following URI in the 746 "IETF XML Registry" [RFC3688]: 748 URI: urn:ietf:params:xml:ns:yang:ietf-dots-call-home 749 Registrant Contact: The IESG. 750 XML: N/A; the requested URI is an XML namespace. 752 This document requests IANA to register the following YANG module in 753 the "YANG Module Names" registry [RFC7950]. 755 Name: ietf-call-home 756 Namespace: urn:ietf:params:xml:ns:yang:ietf-dots-call-home 757 Maintained by IANA: N 758 Prefix: call-home 759 Reference: RFC XXXX 761 5. Security Considerations 763 This document deviates from classic DOTS signal channel usage by 764 having the DOTS server initiate the TLS or DTLS connection. DOTS 765 signal channel related security considerations discussed in 766 Section 10 of [I-D.ietf-dots-signal-channel] MUST be considered. 767 DOTS agents MUST authenticate each other using (D)TLS before a DOTS 768 signal channel session is considered valid. 770 An attacker may launch a DoS attack on the DOTS client by having it 771 perform computationally expensive operations, before deducing that 772 the attacker doesn't possess a valid key. For instance, in TLS 1.3 773 [RFC8446], the ServerHello message contains a Key Share value based 774 on an expensive asymmetric key operation for key establishment. 775 Common precautions mitigating DoS attacks are recommended, such as 776 temporarily blacklisting the source address after a set number of 777 unsuccessful authentication attempts. 779 DOTS servers may not blindly trust mitigation requests from DOTS 780 clients. For example, DOTS servers can use the attack flow 781 information in a mitigation request to enable full-fledged packet 782 inspection function to inspect all the traffic from the compromised 783 to the target or to re-direct the traffic from the compromised device 784 to the target to a DDoS mitigation system to scrub the suspicious 785 traffic. DOTS servers can also seek the consent of DOTS server 786 domain administrator to block the traffic from the compromised device 787 to the target (see Section 3.2.1). 789 6. Privacy Considerations 791 The considerations discussed in [RFC6973] were taken into account to 792 assess whether the DOTS Call Home extension introduces privacy 793 threats. 795 Concretely, the protocol does not leak any new information that can 796 be used to ease surveillance. In particular, the DOTS server is not 797 required to share information that is local to its network (e.g., 798 internal identifiers of an attack source) with the DOTS client. 800 The DOTS Call Home extension does not preclude the validation of 801 mitigation requests received from a DOTS client. For example, a 802 security service running on the CPE may require administrator's 803 consent before the CPE acts upon the mitigation request indicated by 804 the DOTS client. How the consent is obtained is out of scope of this 805 document. 807 Note that a DOTS server can seek for an administrator's consent, 808 validate the request by inspecting the traffic, or proceed with both. 810 The DOTS Call Home extension is only advisory in nature. Concretely, 811 the DOTS Call Home extension does not impose any action to be 812 enforced within the home network; it is up to the DOTS server (and/or 813 network administrator) to decide whether and which actions are 814 required. 816 Moreover, the DOTS Call Home extension avoids misattribution by 817 appropriately identifying the network to which a suspect attack 818 source belongs to (e.g., address sharing issues discussed in 819 Section 3.2.1). 821 Triggers to send a DOTS mitigation request to a DOTS server are 822 deployment-specific. For example, a DOTS client may rely on the 823 output of some DDoS detection systems deployed within the DOTS client 824 domain to detect potential outbound DDoS attacks or on abuse claims 825 received from remote victim networks. Such DDoS detection and 826 mitigation techniques are not meant to track the activity of users, 827 but to protect the Internet and avoid altering the IP reputation of 828 the DOTS client domain. 830 7. Contributors 832 The following individuals have contributed to this document: 834 Joshi Harsha 835 McAfee, Inc. 836 Embassy Golf Link Business Park 837 Bangalore, Karnataka 560071 838 India 840 Email: harsha_joshi@mcafee.com 842 8. Acknowledgements 844 Thanks to Wei Pei, Xia Liang, Roman Danyliw, Dan Wing, Toema 845 Gavrichenkov, Daniel Migault, and Valery Smyslov for the comments. 847 9. References 849 9.1. Normative References 851 [I-D.ietf-dots-signal-channel] 852 K, R., Boucadair, M., Patil, P., Mortensen, A., and N. 853 Teague, "Distributed Denial-of-Service Open Threat 854 Signaling (DOTS) Signal Channel Specification", draft- 855 ietf-dots-signal-channel-31 (work in progress), March 856 2019. 858 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 859 Requirement Levels", BCP 14, RFC 2119, 860 DOI 10.17487/RFC2119, March 1997, 861 . 863 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688, 864 DOI 10.17487/RFC3688, January 2004, 865 . 867 [RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer 868 Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347, 869 January 2012, . 871 [RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types", 872 RFC 6991, DOI 10.17487/RFC6991, July 2013, 873 . 875 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language", 876 RFC 7950, DOI 10.17487/RFC7950, August 2016, 877 . 879 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 880 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 881 May 2017, . 883 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 884 Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018, 885 . 887 9.2. Informative References 889 [I-D.ietf-dots-multihoming] 890 Boucadair, M. and R. K, "Multi-homing Deployment 891 Considerations for Distributed-Denial-of-Service Open 892 Threat Signaling (DOTS)", draft-ietf-dots-multihoming-01 893 (work in progress), January 2019. 895 [I-D.ietf-dots-requirements] 896 Mortensen, A., K, R., and R. Moskowitz, "Distributed 897 Denial of Service (DDoS) Open Threat Signaling 898 Requirements", draft-ietf-dots-requirements-22 (work in 899 progress), March 2019. 901 [I-D.ietf-dots-server-discovery] 902 Boucadair, M., K, R., and P. Patil, "Distributed-Denial- 903 of-Service Open Threat Signaling (DOTS) Server Discovery", 904 draft-ietf-dots-server-discovery-01 (work in progress), 905 April 2019. 907 [I-D.ietf-dots-use-cases] 908 Dobbins, R., Migault, D., Fouant, S., Moskowitz, R., 909 Teague, N., Xia, L., and K. Nishizuka, "Use cases for DDoS 910 Open Threat Signaling", draft-ietf-dots-use-cases-17 (work 911 in progress), January 2019. 913 [I-D.irtf-t2trg-iot-seccons] 914 Garcia-Morchon, O., Kumar, S., and M. Sethi, "State-of- 915 the-Art and Challenges for the Internet of Things 916 Security", draft-irtf-t2trg-iot-seccons-16 (work in 917 progress), December 2018. 919 [RFC4340] Kohler, E., Handley, M., and S. Floyd, "Datagram 920 Congestion Control Protocol (DCCP)", RFC 4340, 921 DOI 10.17487/RFC4340, March 2006, 922 . 924 [RFC4632] Fuller, V. and T. Li, "Classless Inter-domain Routing 925 (CIDR): The Internet Address Assignment and Aggregation 926 Plan", BCP 122, RFC 4632, DOI 10.17487/RFC4632, August 927 2006, . 929 [RFC4732] Handley, M., Ed., Rescorla, E., Ed., and IAB, "Internet 930 Denial-of-Service Considerations", RFC 4732, 931 DOI 10.17487/RFC4732, December 2006, 932 . 934 [RFC4960] Stewart, R., Ed., "Stream Control Transmission Protocol", 935 RFC 4960, DOI 10.17487/RFC4960, September 2007, 936 . 938 [RFC5575] Marques, P., Sheth, N., Raszuk, R., Greene, B., Mauch, J., 939 and D. McPherson, "Dissemination of Flow Specification 940 Rules", RFC 5575, DOI 10.17487/RFC5575, August 2009, 941 . 943 [RFC6973] Cooper, A., Tschofenig, H., Aboba, B., Peterson, J., 944 Morris, J., Hansen, M., and R. Smith, "Privacy 945 Considerations for Internet Protocols", RFC 6973, 946 DOI 10.17487/RFC6973, July 2013, 947 . 949 [RFC7596] Cui, Y., Sun, Q., Boucadair, M., Tsou, T., Lee, Y., and I. 950 Farrer, "Lightweight 4over6: An Extension to the Dual- 951 Stack Lite Architecture", RFC 7596, DOI 10.17487/RFC7596, 952 July 2015, . 954 [RFC7597] Troan, O., Ed., Dec, W., Li, X., Bao, C., Matsushima, S., 955 Murakami, T., and T. Taylor, Ed., "Mapping of Address and 956 Port with Encapsulation (MAP-E)", RFC 7597, 957 DOI 10.17487/RFC7597, July 2015, 958 . 960 [RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home", 961 RFC 8071, DOI 10.17487/RFC8071, February 2017, 962 . 964 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams", 965 BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018, 966 . 968 [RFC8512] Boucadair, M., Ed., Sivakumar, S., Jacquenet, C., 969 Vinapamula, S., and Q. Wu, "A YANG Module for Network 970 Address Translation (NAT) and Network Prefix Translation 971 (NPT)", RFC 8512, DOI 10.17487/RFC8512, January 2019, 972 . 974 [RFC8513] Boucadair, M., Jacquenet, C., and S. Sivakumar, "A YANG 975 Data Model for Dual-Stack Lite (DS-Lite)", RFC 8513, 976 DOI 10.17487/RFC8513, January 2019, 977 . 979 [RFC8517] Dolson, D., Ed., Snellman, J., Boucadair, M., Ed., and C. 980 Jacquenet, "An Inventory of Transport-Centric Functions 981 Provided by Middleboxes: An Operator Perspective", 982 RFC 8517, DOI 10.17487/RFC8517, February 2019, 983 . 985 Authors' Addresses 987 Tirumaleswar Reddy 988 McAfee, Inc. 989 Embassy Golf Link Business Park 990 Bangalore, Karnataka 560071 991 India 993 Email: kondtir@gmail.com 995 Mohamed Boucadair 996 Orange 997 Rennes 35000 998 France 1000 Email: mohamed.boucadair@orange.com 1002 Jon Shallow 1003 UK 1005 Email: supjps-ietf@jpshallow.com