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Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (September 15, 2019) is 972 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 1 error (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 I2NSF Working Group J. Jeong 3 Internet-Draft Sungkyunkwan University 4 Intended status: Informational S. Hyun 5 Expires: March 18, 2020 Myongji University 6 T. Ahn 7 Korea Telecom 8 S. Hares 9 Huawei 10 D. Lopez 11 Telefonica I+D 12 September 15, 2019 14 Applicability of Interfaces to Network Security Functions to Network- 15 Based Security Services 16 draft-ietf-i2nsf-applicability-18 18 Abstract 20 This document describes the applicability of Interface to Network 21 Security Functions (I2NSF) to network-based security services in 22 Network Functions Virtualization (NFV) environments, such as 23 firewall, deep packet inspection, or attack mitigation engines. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on March 18, 2020. 42 Copyright Notice 44 Copyright (c) 2019 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (https://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 60 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 61 3. I2NSF Framework . . . . . . . . . . . . . . . . . . . . . . . 5 62 4. Time-dependent Web Access Control Service . . . . . . . . . . 8 63 5. Intent-based Security Services . . . . . . . . . . . . . . . 13 64 6. I2NSF Framework with SFC . . . . . . . . . . . . . . . . . . 15 65 7. I2NSF Framework with SDN . . . . . . . . . . . . . . . . . . 17 66 7.1. Firewall: Centralized Firewall System . . . . . . . . . . 19 67 7.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security 68 System . . . . . . . . . . . . . . . . . . . . . . . . . 20 69 7.3. Attack Mitigation: Centralized DDoS-attack Mitigation 70 System . . . . . . . . . . . . . . . . . . . . . . . . . 20 71 8. I2NSF Framework with NFV . . . . . . . . . . . . . . . . . . 21 72 9. Security Considerations . . . . . . . . . . . . . . . . . . . 23 73 10. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24 74 11. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 24 75 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 76 12.1. Normative References . . . . . . . . . . . . . . . . . . 24 77 12.2. Informative References . . . . . . . . . . . . . . . . . 26 78 Appendix A. Changes from draft-ietf-i2nsf-applicability-17 . . . 28 79 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 28 81 1. Introduction 83 Interface to Network Security Functions (I2NSF) defines a framework 84 and interfaces for interacting with Network Security Functions 85 (NSFs). Note that an NSF is defined as software that provides a set 86 of security-related services, such as (i) detecting unwanted 87 activity, (ii) blocking or mitigating the effect of such unwanted 88 activity in order to fulfill service requirements, and (iii) 89 supporting communication stream integrity and confidentiality 90 [i2nsf-terminology]. 92 The I2NSF framework allows heterogeneous NSFs developed by different 93 security solution vendors to be used in the Network Functions 94 Virtualization (NFV) environment [ETSI-NFV] by utilizing the 95 capabilities of such NSFs through I2NSF interfaces such as Customer- 96 Facing Interface [consumer-facing-inf-dm] and NSF-Facing Interface 98 [nsf-facing-inf-dm]. In the I2NSF framework, each NSF initially 99 registers the profile of its own capabilities with the Security 100 Controller (i.e., network operator management system [RFC8329]) of 101 the I2NSF system via the Registration Interface 102 [registration-inf-dm]. This registration enables an I2NSF User 103 (i.e., network security administrator) to select and use the NSF to 104 enforce a given security policy. Note that Developer's Management 105 System (DMS) is management software that provides a vendor's security 106 service software as a Virtual Network Function (VNF) in an NFV 107 environment (or middlebox in the legacy network) as an NSF, and 108 registers the capabilities of an NSF into Security Controller via 109 Registration Interface for a security service [RFC8329]. 111 Security Controller maintains the mapping between a capability and an 112 NSF, so it can perform to translate a high-level security policy 113 received from I2NSF User to a low-level security policy configured 114 and enforced in an NSF [policy-translation]. Security Controller can 115 monitor the states and security attacks in NSFs through NSF 116 monitoring [nsf-monitoring-dm]. 118 This document illustrates the applicability of the I2NSF framework 119 with five different scenarios: 121 1. The enforcement of time-dependent web access control. 123 2. The support of intent-based security services through I2NSF and 124 Security Policy Translator [policy-translation]. 126 3. The application of I2NSF to a Service Function Chaining (SFC) 127 environment [RFC7665]. 129 4. The integration of the I2NSF framework with Software-Defined 130 Networking (SDN) [RFC7149] to provide different security 131 functionality such as firewalls [opsawg-firewalls], Deep Packet 132 Inspection (DPI), and Distributed Denial of Service (DDoS) attack 133 mitigation. 135 5. The use of Network Functions Virtualization (NFV) [ETSI-NFV] as a 136 supporting technology. 138 The implementation of I2NSF in these scenarios has allowed us to 139 verify the applicability and effectiveness of the I2NSF framework for 140 a variety of use cases. 142 2. Terminology 144 This document uses the terminology described in [RFC7665], [RFC7149], 145 [ITU-T.Y.3300], [ONF-SDN-Architecture], [ITU-T.X.800], 146 [NFV-Terminology], [RFC8329], and [i2nsf-terminology]. In addition, 147 the following terms are defined below: 149 o Centralized DDoS-attack Mitigation System: A centralized mitigator 150 that can establish and distribute access control policy rules into 151 network resources for efficient DDoS-attack mitigation. 153 o Centralized Firewall System: A centralized firewall that can 154 establish and distribute policy rules into network resources for 155 efficient firewall management. 157 o Centralized VoIP Security System: A centralized security system 158 that handles the security functions required for VoIP and VoLTE 159 services. 161 o Firewall: A service function at the junction of two network 162 segments that inspects some suspicious packets that attempt to 163 cross the boundary. It also rejects any packet that does not 164 satisfy certain criteria for, for example, disallowed port numbers 165 or IP addresses. 167 o Network Function: A functional block within a network 168 infrastructure that has well-defined external interfaces and well- 169 defined functional behavior [NFV-Terminology]. 171 o Network Functions Virtualization (NFV): A principle of separating 172 network functions (or network security functions) from the 173 hardware they run on by using virtual hardware abstraction 174 [NFV-Terminology]. 176 o Network Security Function (NSF): Software that provides a set of 177 security-related services. Examples include detecting unwanted 178 activity and blocking or mitigating the effect of such unwanted 179 activity in order to fulfill service requirements. The NSF can 180 also help in supporting communication stream integrity and 181 confidentiality [i2nsf-terminology]. 183 o Security Policy Translator (SPT): Software that translates a high- 184 level security policy for the Consumer-Facing Interface into a 185 low-level security policy for the NSF-Facing Interface 186 [policy-translation]. The SPT is a core part of the Security 187 Controller in the I2NSF system. 189 o Service Function Chaining (SFC): The execution of an ordered set 190 of abstract service functions (i.e., network functions) according 191 to ordering constraints that must be applied to packets, frames, 192 and flows selected as a result of classification. The implied 193 order may not be a linear progression as the architecture allows 194 for SFCs that copy to more than one branch, and also allows for 195 cases where there is flexibility in the order in which service 196 functions need to be applied [RFC7665]. 198 o Software-Defined Networking (SDN): A set of techniques that 199 enables to directly program, orchestrate, control, and manage 200 network resources, which facilitates the design, delivery and 201 operation of network services in a dynamic and scalable manner 202 [ITU-T.Y.3300]. 204 +------------+ 205 | I2NSF User | 206 +------------+ 207 ^ 208 | Consumer-Facing Interface 209 v 210 +-------------------+ Registration +-----------------------+ 211 |Security Controller|<-------------------->|Developer's Mgmt System| 212 +-------------------+ Interface +-----------------------+ 213 ^ 214 | NSF-Facing Interface 215 v 216 +----------------+ +---------------+ +-----------------------+ 217 | NSF-1 |-| NSF-2 |...| NSF-n | 218 | (Firewall) | | (Web Filter) | |(DDoS-Attack Mitigator)| 219 +----------------+ +---------------+ +-----------------------+ 221 Figure 1: I2NSF Framework 223 3. I2NSF Framework 225 This section summarizes the I2NSF framework as defined in [RFC8329]. 226 As shown in Figure 1, an I2NSF User can use security functions by 227 delivering high-level security policies, which specify security 228 requirements that the I2NSF user wants to enforce, to the Security 229 Controller via the Consumer-Facing Interface (CFI) 230 [consumer-facing-inf-dm]. 232 The Security Controller receives and analyzes the high-level security 233 policies from an I2NSF User, and identifies what types of security 234 capabilities are required to meet these high-level security policies. 235 The Security Controller then identifies NSFs that have the required 236 security capabilities, and generates low-level security policies for 237 each of the NSFs so that the high-level security policies are 238 eventually enforced by those NSFs [policy-translation]. Finally, the 239 Security Controller sends the generated low-level security policies 240 to the NSFs via the NSF-Facing Interface (NFI) [nsf-facing-inf-dm]. 242 As shown in Figure 1, with a Developer's Management System (called 243 DMS), developers (or vendors) inform the Security Controller of the 244 capabilities of the NSFs through the Registration Interface (RI) 245 [registration-inf-dm] for registering (or deregistering) the 246 corresponding NSFs. Note that the lifecycle management of NSF code 247 from DMS (e.g., downloading of NSF modules and testing of NSF code) 248 is out of scope for I2NSF. 250 The Consumer-Facing Interface can be implemented with the Consumer- 251 Facing Interface YANG data model [consumer-facing-inf-dm] using 252 RESTCONF [RFC8040] which befits a web-based user interface for an 253 I2NSF User to send a Security Controller a high-level security 254 policy. Data models specified by YANG [RFC6020] describe high-level 255 security policies to be specified by an I2NSF User. The data model 256 defined in [consumer-facing-inf-dm] can be used for the I2NSF 257 Consumer-Facing Interface. Note that an inside attacker at the I2NSF 258 User can misuse the I2NSF system so that the network system under the 259 I2NSF system is vulnerable to security attacks. To handle this type 260 of threat, the Security Controller needs to monitor the activities of 261 all the I2NSF Users as well as the NSFs through the I2NSF NSF 262 monitoring functionality [nsf-monitoring-dm]. Note that the 263 monitoring of the I2NSF Users is out of scope for I2NSF. 265 The NSF-Facing Interface can be implemented with the NSF-Facing 266 Interface YANG data model [nsf-facing-inf-dm] using NETCONF [RFC6241] 267 which befits a command-line-based remote-procedure call for a 268 Security Controller to configure an NSF with a low-level security 269 policy. Data models specified by YANG [RFC6020] describe low-level 270 security policies for the sake of NSFs, which are translated from the 271 high-level security policies by the Security Controller. The data 272 model defined in [nsf-facing-inf-dm] can be used for the I2NSF NSF- 273 Facing Interface. 275 The Registration Interface can be implemented with the Registration 276 Interface YANG data model [registration-inf-dm] using NETCONF 277 [RFC6241] which befits a command-line-based remote-procedure call for 278 a DMS to send a Security Controller an NSF's capability information. 279 Data models specified by YANG [RFC6020] describe the registration of 280 an NSF's capabilities to enforce security services at the NSF. The 281 data model defined in [registration-inf-dm] can be used for the I2NSF 282 Registration Interface. 284 The I2NSF framework can chain multiple NSFs to implement low-level 285 security policies with the SFC architecture [RFC7665]. 287 The following sections describe different security service scenarios 288 illustrating the applicability of the I2NSF framework. 290 291 292 block_website 293 294 block_website_during_working_hours 295 296 297 09:00 298 18:00 299 300 301 302 303 304 Staff_Members'_PCs 305 306 307 308 309 SNS_Websites 310 311 312 313 314 drop 315 316 317 319 Figure 2: A High-level Security Policy XML File for Time-based Web 320 Filter 322 323 325 326 block_website 327 328 block_website_during_working_hours 329 330 331 09:00 332 18:00 333 334 335 336 337 338 339 2001:DB8:10:1::10 340 2001:DB8:10:1::20 341 2001:DB8:10:1::30 342 343 344 345 346 example1.com 347 example2.com 348 example3.com 349 example4.com 350 351 352 353 354 drop 355 356 357 358 359 361 Figure 3: A Low-level Security Policy XML File for Time-based Web 362 Filter 364 4. Time-dependent Web Access Control Service 366 This service scenario assumes that an enterprise network 367 administrator wants to control the staff members' access to a 368 particular Internet service (e.g., social networking service (SNS)) 369 during business hours. The following is an example high-level 370 security policy rule for a web filter that the administrator 371 requests: Block the staff members' access to SNS websites from 9 AM 372 (i.e., 09:00) to 6 PM (i.e., 18:00) by dropping their packets. 373 Figure 2 is a high-level security policy XML code for the web filter 374 that is sent from the I2NSF User to the Security Controller via the 375 Consumer-Facing Interface [consumer-facing-inf-dm]. 377 The security policy name is "block_website" with the tag "policy- 378 name", and the security policy rule name is 379 "block_website_during_working_hours" with the tag "rule-name". The 380 filtering event has the time span where the filtering begin time is 381 the time "09:00" (i.e., 9:00AM) with the tag "begin-time", and the 382 filtering end time is the time "18:00" (i.e., 6:00PM) with the tag 383 "end-time". The filtering condition has the source target of 384 "Staff_Members'_PCs" with the tag "src-target", and the destination 385 target of "SNS_Websites" with the tag "dest-target". 387 Assume that "Staff_Members'_PCs" are 2001:DB8:10:1::10, 388 2001:DB8:10:1::20, and 2001:DB8:10:1::30, and that "SNS_Websites" are 389 example1.com, example2.com, example3.com, and example4.com, as shown 390 in Figure 3. Note that Figure 3 is a low-level security policy XML 391 code for the web filter that is sent from the Security Controller to 392 an NSF via the NSF-Facing Interface [nsf-facing-inf-dm]. 394 The source target can by translated by the Security Policy Translator 395 (SPT) in the Security Controller to the IP addresses of computers (or 396 mobile devices) used by the staff members. Refer to Section 5 for 397 the detailed description of the SPT. The destination target can also 398 be translated by the SPT to the actual websites corresponding to the 399 symbolic website name "SNS_Websites", and then either each website's 400 URL or the corresponding IP address(es) can be used by both firewall 401 and web filter. The action is to "drop" the packets satisfying the 402 above event and condition with the tag "primary-action". 404 After receiving the high-level security policy, the Security 405 Controller identifies required security capabilities, e.g., IP 406 address and port number inspection capabilities and URL inspection 407 capability. In this scenario, it is assumed that the IP address and 408 port number inspection capabilities are required to check whether a 409 received packet is an HTTP-session packet from a staff member, which 410 is part of an HTTP session generated by the staff member. The URL 411 inspection capability is required to check whether the target URL of 412 a received packet is one of the target websites (i.e., example1.com, 413 example2.com, example3.com, and example4.com) or not. 415 The Security Controller maintains the security capabilities of each 416 active NSF in the I2NSF system, which have been reported by the 417 Developer's Management System via the Registration interface. Based 418 on this information, the Security Controller identifies NSFs that can 419 perform the IP address and port number inspection and URL inspection 420 through the security policy translation in Section 5. In this 421 scenario, it is assumed that a firewall NSF has the IP address and 422 port number inspection capabilities and a web filter NSF has URL 423 inspection capability. 425 The Security Controller generates a low-level security policy for the 426 NSFs to perform IP address and port number inspection, URL 427 inspection, and time checking, which is shown in Figure 3. 428 Specifically, the Security Controller may interoperate with an access 429 control server in the enterprise network in order to retrieve the 430 information (e.g., IP address in use, company identifier (ID), and 431 role) of each employee that is currently using the network. Based on 432 the retrieved information, the Security Controller generates a low- 433 level security policy to check whether the source IP address of a 434 received packet matches any one being used by a staff member. 436 In addition, the low-level security policy's rule (shortly, low-level 437 security rule) should be able to determine that a received packet 438 uses either the HTTP protocol without Transport Layer Security (TLS) 439 [RFC8446] or the HTTP protocol with TLS as HTTPS. The low-level 440 security rule for web filter checks that the target URL field of a 441 received packet is equal to one of the target SNS websites (i.e., 442 example1.com, example2.com, example3.com, and example4.com), or that 443 the destination IP address of a received packet is an IP address 444 corresponding to one of the SNS websites. Note that if HTTPS is used 445 for an HTTP-session packet, the HTTP protocol header is encrypted, so 446 the URL information may not be seen from the packet for the web 447 filtering. Thus, the IP address(es) corresponding to the target URL 448 needs to be obtained from the certificate in TLS versions prior to 449 1.3 [RFC8446] or the Server Name Indication (SNI) in a TCP-session 450 packet in TLS versions without the encrypted SNI [tls-esni]. Also, 451 to obtain IP address(es) corresponding to a target URL, the DNS name 452 resolution process can be observed through a packet capturing tool 453 because the DNS name resolution will translate the target URL into IP 454 address(es). The IP addresses obtained through either TLS or DNS can 455 be used by both firewall and web filter for whitelisting or 456 blacklisting the TCP five-tuples of HTTP sessions. 458 Finally, the Security Controller sends the low-level security policy 459 of the IP address and port number inspection to the firewall NSF and 460 the low-level security policy for URL inspection to the web filter 461 NSF. 463 The following describes how the time-dependent web access control 464 service is enforced by the NSFs of firewall and web filter. 466 1. A staff member tries to access one of the target SNS websites 467 (i.e., example1.com, example2.com, example3.com, and 468 example4.com) during business hours, e.g., 10 AM. 470 2. The packet is forwarded from the staff member's device to the 471 firewall, and the firewall checks the source IP address and port 472 number. Now the firewall identifies the received packet is an 473 HTTP-session packet from the staff member. 475 3. The firewall triggers the web filter to further inspect the 476 packet, and the packet is forwarded from the firewall to the web 477 filter. The SFC architecture [RFC7665] can be utilized to 478 support such packet forwarding in the I2NSF framework. 480 4. The web filter checks the received packet's target URL field or 481 its destination IP address corresponding to the target URL, and 482 detects that the packet is being sent to the server for 483 example1.com. The web filter then checks that the current time 484 is within business hours. If so, the web filter drops the 485 packet, and consequently the staff member's access to one of the 486 SNS websites (i.e., example1.com, example2.com, example3.com, and 487 example4.com) during business hours is blocked. 489 +------------------------+-------------------------+ 490 | | 491 | I2NSF User | 492 | | 493 +------------------------+-------------------------+ 494 | Consumer-Facing Interface 495 | 496 High-level Security Policy 497 Security | 498 Controller V 499 +------------------------+-------------------------+ 500 | Security Policy | | 501 | Translator | | 502 | +---------------------+----------------------+ | 503 | | | | | 504 | | +-------+--------+ | | 505 | | | Data Extractor | | | 506 | | +-------+--------+ | | 507 | | | Extracted Data from | | 508 | | V High-level Policy | | 509 | | +-------+--------+ +------+ | | 510 | | | Data Converter |<-->|NSF DB| | | 511 | | +-------+--------+ +------+ | | 512 | | | Required Data for | | 513 | | V Target NSFs | | 514 | | +-------+--------+ | | 515 | | |Policy Generator| | | 516 | | +-------+--------+ | | 517 | | | | | 518 | +---------------------+----------------------+ | 519 | | | 520 +------------------------+-------------------------+ 521 | NSF-Facing Interface 522 | 523 Low-level Security Policy 524 | 525 V 526 +------------------------+-------------------------+ 527 | | 528 | NSF(s) | 529 | | 530 +------------------------+-------------------------+ 532 Figure 4: Security Policy Translation and Enforcement in I2NSF System 534 5. Intent-based Security Services 536 I2NSF aims at providing intent-based security services to configure 537 specific security policies into NSFs with customer-friendly secuirty 538 policies at a high level. For example, when an I2NSF User submits a 539 high-level security policy (e.g., web filtering as shown in Figure 2) 540 to the Security Controller, the Security Policy Tranlator (SPT) in 541 the Security Controller will translate it into the correspondong low- 542 level security policy as shown in Figure 3 [policy-translation]. A 543 security administrator using the I2NSF User can describe a security 544 policy without the knowledge of the detailed information about 545 subjects (e.g., source and destination) and objects (e.g., web 546 traffic) of the security policy's rule(s). 548 Figure 4 shows the security policy translation and enforcement in the 549 I2NSF system [policy-translation]. As shown in Figure 4, an I2NSF 550 User delivers a high-level security policy to the Security Controller 551 using the Consumer-Facing Interface (denoted as CFI). The high-level 552 security policy is translated by the SPT in the Security Controller 553 into the corresponding low-level security policy which is 554 understandable by target NSF(s). The Security Controller delivers 555 the low-level security policy to the appropriate NSF(s) to enforce 556 the policy's rules. 558 The SPT consists of three modules for security policy translations 559 such as Data Extractor, Data Converter, and Policy Generator, as 560 shown in Figure 4. The Data Extractor extracts data from a high- 561 level security policy delivered by the I2NSF User. The data 562 correspond to the leaf nodes in the YANG data model for the Consumer- 563 Facing Interface. In the high-level policy in Figure 2, the data are 564 the tag values of policy-name, rule-name, begin-time, end-time, src- 565 target, dest-target, and primary-action. That is, the tag values are 566 "block_website", "block_website_during_working_hours", "09:00", 567 "18:00", "Staff_Members'_PCs", "SNS_Websites", and "drop." 569 The Data Converter converts the extracted high-level policy data 570 received from the Data Extractor into the corresponding low-level 571 policy data. The low-level policy data have the capability 572 information of NSFs to be selected as target NSFs for the required 573 security service enforcement specified by the high-level security 574 policy. The tag values in the extracted high-level policy data are 575 replaced with the tag values in the low-level policy data, which are 576 the leaf nodes of the YANG data model for the NSF-Facing Interface 577 (denoted as NFI). The value of each leaf node in CFI is translated 578 into the value of the corresponding leaf node in NFI. For example, 579 "block_website" of policy-name in CFI (in Figure 2) is translated 580 into "block_website" of system-policy-name in NFI (in Figure 3). The 581 tag values of rule-name, begin-time, end-time, and primary-action in 582 CFI are mapped into the same values of rule-name, begin-time, end- 583 time, and egress-action in NFI. However, the tag values of src- 584 target and dest-target in CFI are translated into IP addresses and 585 URLs, respectively, for the sake of NFI. That is, 586 "Staff_Members'_PCs" of CFI is translated into three IPv6 addresses 587 such as "2001:DB8:10:1::10", "2001:DB8:10:1::20", and 588 "2001:DB8:10:1::30" for the sake of NFI. Also, "SNS_Websites" of CFI 589 is translated into four URLs such as "example1.com", "example2.com", 590 "example3.com", and "example4.com" for the sake of NFI. In addition 591 to the data conversion, the Data Converter searches for appropriate 592 NSFs having capabilities corresponding to the leaf nodes of the YANG 593 data model for NFI. For the data conversion and NSF search, an NSF 594 database (denoted as NSF DB) can be consulted, as shown in Figure 4, 595 because the NSF DB has the capability information of NSFs that the 596 DMS(s) registered with the Security Controller using the Registration 597 Interface. 599 The Policy Generator generates a low-level security policy 600 corresponding to the low-level policy data made by the Data Converter 601 per a target NSF. That is, the Policy Generator can build such a 602 low-level security policy XML file like Figure 3 with the NSF DB 603 because the NSF DB has the mapping information between the CFI YANG 604 data model and the NFI YANG data model. 606 Therefore, by allowing the I2NSF User to express its security policy 607 without knowing the detailed information of entities for security 608 policies, the I2NSF can efficiently support the intent-based security 609 services with the help of the security policy translator along with 610 the NSF DB. 612 +------------+ 613 | I2NSF User | 614 +------------+ 615 ^ 616 | Consumer-Facing Interface 617 v 618 +-------------------+ Registration +-----------------------+ 619 |Security Controller|<-------------------->|Developer's Mgmt System| 620 +-------------------+ Interface +-----------------------+ 621 ^ ^ 622 | | NSF-Facing Interface 623 | |------------------------- 624 | | 625 | NSF-Facing Interface | 626 +-----v-----------+ +------v-------+ 627 | +-----------+ | ------>| NSF-1 | 628 | |Classifier | | | | (Firewall) | 629 | +-----------+ | | +--------------+ 630 | +-----+ |<-----| +--------------+ 631 | | SFF | | |----->| NSF-2 | 632 | +-----+ | | | (DPI) | 633 +-----------------+ | +--------------+ 634 | . 635 | . 636 | . 637 | +-----------------------+ 638 ------>| NSF-n | 639 |(DDoS-Attack Mitigator)| 640 +-----------------------+ 642 Figure 5: An I2NSF Framework with SFC 644 6. I2NSF Framework with SFC 646 In the I2NSF architecture, an NSF can trigger an advanced security 647 action (e.g., DPI or DDoS attack mitigation) on a packet based on the 648 result of its own security inspection of the packet. For example, a 649 firewall triggers further inspection of a suspicious packet with DPI. 650 For this advanced security action to be fulfilled, the suspicious 651 packet should be forwarded from the current NSF to the successor NSF. 652 SFC [RFC7665] is a technology that enables this advanced security 653 action by steering a packet with multiple service functions (e.g., 654 NSFs), and this technology can be utilized by the I2NSF architecture 655 to support the advanced security action. 657 Figure 5 shows an I2NSF framework with the support of SFC. As shown 658 in the figure, SFC generally requires classifiers and service 659 function forwarders (SFFs); classifiers are responsible for 660 determining which service function path (SFP) (i.e., an ordered 661 sequence of service functions) a given packet should pass through, 662 according to pre-configured classification rules, and SFFs perform 663 forwarding the given packet to the next service function (e.g., NSF) 664 on the SFP of the packet by referring to their forwarding tables. In 665 the I2NSF architecture with SFC, the Security Controller can take 666 responsibilities of generating classification rules for classifiers 667 and forwarding tables for SFFs. By analyzing high-level security 668 policies from I2NSF users, the Security Controller can construct SFPs 669 that are required to meet the high-level security policies, generates 670 classification rules of the SFPs, and then configures classifiers 671 with the classification rules over NSF-Facing Interface so that 672 relevant traffic packets can follow the SFPs. Also, based on the 673 global view of NSF instances available in the system, the Security 674 Controller constructs forwarding tables, which are required for SFFs 675 to forward a given packet to the next NSF over the SFP, and 676 configures SFFs with those forwarding tables over NSF-Facing 677 Interface. 679 To trigger an advanced security action in the I2NSF architecture, the 680 current NSF appends metadata describing the security capability 681 required to the suspicious packet via a network service header (NSH) 682 [RFC8300]. It then sends the packet to the classifier. Based on the 683 metadata information, the classifier searches an SFP which includes 684 an NSF with the required security capability, changes the SFP-related 685 information (e.g., service path identifier and service index 686 [RFC8300]) of the packet with the new SFP that has been found, and 687 then forwards the packet to the SFF. When receiving the packet, the 688 SFF checks the SFP-related information such as the service path 689 identifier and service index contained in the packet and forwards the 690 packet to the next NSF on the SFP of the packet, according to its 691 forwarding table. 693 +------------+ 694 | I2NSF User | 695 +------------+ 696 ^ 697 | Consumer-Facing Interface 698 v 699 +-------------------+ Registration +-----------------------+ 700 |Security Controller|<-------------------->|Developer's Mgmt System| 701 +-------------------+ Interface +-----------------------+ 702 ^ ^ 703 | | NSF-Facing Interface 704 | v 705 | +----------------+ +---------------+ +-----------------------+ 706 | | NSF-1 |-| NSF-2 |...| NSF-n | 707 | | (Firewall) | | (DPI) | |(DDoS-Attack Mitigator)| 708 | +----------------+ +---------------+ +-----------------------+ 709 | 710 | 711 | SDN Network 712 +--|----------------------------------------------------------------+ 713 | V NSF-Facing Interface | 714 | +----------------+ | 715 | | SDN Controller | | 716 | +----------------+ | 717 | ^ | 718 | | SDN Southbound Interface | 719 | v | 720 | +--------+ +------------+ +--------+ +--------+ | 721 | |Switch-1|-| Switch-2 |-|Switch-3|.......|Switch-m| | 722 | | | |(Classifier)| | (SFF) | | | | 723 | +--------+ +------------+ +--------+ +--------+ | 724 +-------------------------------------------------------------------+ 726 Figure 6: An I2NSF Framework with SDN Network 728 7. I2NSF Framework with SDN 730 This section describes an I2NSF framework with SDN for I2NSF 731 applicability and use cases, such as firewall, deep packet 732 inspection, and DDoS-attack mitigation functions. SDN enables some 733 packet filtering rules to be enforced in network forwarding elements 734 (e.g., switch) by controlling their packet forwarding rules. By 735 taking advantage of this capability of SDN, it is possible to 736 optimize the process of security service enforcement in the I2NSF 737 system. For example, for efficient firewall services, simple packet 738 filtering can be performed by SDN forwarding elements (e.g., 739 switches), and complicated packet filtering based on packet payloads 740 can be performed by a firewall NSF. This optimized firewall using 741 both SDN forwarding elements and a firewall NSF is more efficient 742 than a firewall where SDN forwarding elements forward all the packets 743 to a firewall NSF for packet filtering. This is because packets to 744 be filtered out can be early dropped by SDN forwarding elements 745 without consuming further network bandwidth due to the forwarding of 746 the packets to the firewall NSF. 748 Figure 6 shows an I2NSF framework [RFC8329] with SDN networks to 749 support network-based security services. In this system, the 750 enforcement of security policy rules is divided into the SDN 751 forwarding elements (e.g., a switch running as either a hardware 752 middle box or a software virtual switch) and NSFs (e.g., a firewall 753 running in a form of a VNF [ETSI-NFV]). Note that NSFs are created 754 or removed by the NFV Management and Orchestration (MANO) 755 [ETSI-NFV-MANO], performing the lifecycle management of NSFs as VNFs. 756 Refer to Section 8 for the detailed discussion of the NSF lifecycle 757 management in the NFV MANO for I2NSF. For security policy 758 enforcement (e.g., packet filtering), the Security Controller 759 instructs the SDN Controller via NSF-Facing Interface so that SDN 760 forwarding elements can perform the required security services with 761 flow tables under the supervision of the SDN Controller. 763 As an example, let us consider two different types of security rules: 764 Rule A is a simple packet filtering rule that checks only the IP 765 address and port number of a given packet, whereas rule B is a time- 766 consuming packet inspection rule for analyzing whether an attached 767 file being transmitted over a flow of packets contains malware. Rule 768 A can be translated into packet forwarding rules of SDN forwarding 769 elements and thus be enforced by these elements. In contrast, rule B 770 cannot be enforced by forwarding elements, but it has to be enforced 771 by NSFs with anti-malware capability. Specifically, a flow of 772 packets is forwarded to and reassembled by an NSF to reconstruct the 773 attached file stored in the flow of packets. The NSF then analyzes 774 the file to check the existence of malware. If the file contains 775 malware, the NSF drops the packets. 777 In an I2NSF framework with SDN, the Security Controller can analyze 778 given security policy rules and automatically determine which of the 779 given security policy rules should be enforced by SDN forwarding 780 elements and which should be enforced by NSFs. If some of the given 781 rules requires security capabilities that can be provided by SDN 782 forwarding elements, then the Security Controller instructs the SDN 783 Controller via NSF-Facing Interface so that SDN forwarding elements 784 can enforce those security policy rules with flow tables under the 785 supervision of the SDN Controller. Or if some rules require security 786 capabilities that cannot be provided by SDN forwarding elements but 787 by NSFs, then the Security Controller instructs relevant NSFs to 788 enforce those rules. 790 The distinction between software-based SDN forwarding elements and 791 NSFs, which can both run as VNFs, may be necessary for some 792 management purposes in this system. Note that an SDN forwarding 793 element (i.e., switch) is a specific type of VNF rather than an NSF 794 because an NSF is for security services rather than for packet 795 forwarding. For this distinction, we can take advantage of the NFV 796 MANO where there is a subsystem that maintains the descriptions of 797 the capabilities each VNF can offer [ETSI-NFV-MANO]. This subsystem 798 can determine whether a given software element (VNF instance) is an 799 NSF or a virtualized SDN switch. For example, if a VNF instance has 800 anti-malware capability according to the description of the VNF, it 801 could be considered as an NSF. A VNF onboarding system 802 [VNF-ONBOARDING] can be used as such a subsystem that maintains the 803 descriptions of each VNF to tell whether a VNF instance is for an NSF 804 or for a virtualized SDN switch. 806 For the support of SFC in the I2NSF framework with SDN, as shown in 807 Figure 6, network forwarding elements (e.g., switch) can play the 808 role of either SFC Classifier or SFF, which are explained in 809 Section 6. Classifier and SFF have an NSF-Facing Interface with 810 Security Controller. This interface is used to update security 811 service function chaining information for traffic flows. For 812 example, when it needs to update an SFP for a traffic flow in an SDN 813 network, as shown in Figure 6, SFF (denoted as Switch-3) asks 814 Security Controller to update the SFP for the traffic flow (needing 815 another security service as an NSF) via NSF-Facing Interface. This 816 update lets Security Controller ask Classifier (denoted as Switch-2) 817 to update the mapping between the traffic flow and SFP in Classifier 818 via NSF-Facing Interface. 820 The following subsections introduce three use cases from [RFC8192] 821 for cloud-based security services: (i) firewall system, (ii) deep 822 packet inspection system, and (iii) attack mitigation system. 824 7.1. Firewall: Centralized Firewall System 826 A centralized network firewall can manage each network resource and 827 apply common rules to individual network elements (e.g., switch). 828 The centralized network firewall controls each forwarding element, 829 and firewall rules can be added or deleted dynamically. 831 A time-based firewall can be enforced with packet filtering rules and 832 a time span (e.g., work hours). With this time-based firewall, a 833 time-based security policy can be enforced, as explained in 834 Section 4. For example, employees at a company are allowed to access 835 social networking service websites during lunch time or after work 836 hours. 838 7.2. Deep Packet Inspection: Centralized VoIP/VoLTE Security System 840 A centralized VoIP/VoLTE security system can monitor each VoIP/VoLTE 841 flow and manage VoIP/VoLTE security rules, according to the 842 configuration of a VoIP/VoLTE security service called VoIP Intrusion 843 Prevention System (IPS). This centralized VoIP/VoLTE security system 844 controls each switch for the VoIP/VoLTE call flow management by 845 manipulating the rules that can be added, deleted or modified 846 dynamically. 848 The centralized VoIP/VoLTE security system can cooperate with a 849 network firewall to realize VoIP/VoLTE security service. 850 Specifically, a network firewall performs the basic security check of 851 an unknown flow's packet observed by a switch. If the network 852 firewall detects that the packet is an unknown VoIP call flow's 853 packet that exhibits some suspicious patterns, then it triggers the 854 VoIP/VoLTE security system for more specialized security analysis of 855 the suspicious VoIP call packet. 857 7.3. Attack Mitigation: Centralized DDoS-attack Mitigation System 859 A centralized DDoS-attack mitigation can manage each network resource 860 and configure rules to each switch for DDoS-attack mitigation (called 861 DDoS-attack Mitigator) on a common server. The centralized DDoS- 862 attack mitigation system defends servers against DDoS attacks outside 863 the private network, that is, from public networks 864 [RFC8612][dots-architecture]. 866 Servers are categorized into stateless servers (e.g., DNS servers) 867 and stateful servers (e.g., web servers). For DDoS-attack 868 mitigation, the forwarding of traffic flows in switches can be 869 dynamically configured such that malicious traffic flows are handled 870 by the paths separated from normal traffic flows in order to minimize 871 the impact of those malicious traffic on the servers. This flow path 872 separation can be done by a flow forwarding path management scheme 873 [dots-architecture][AVANT-GUARD]. This management should consider 874 the load balance among the switches for the defense against DDoS 875 attacks. 877 So far this section has described the three use cases for network- 878 based security services using the I2NSF framework with SDN networks. 879 To support these use cases in the proposed data-driven security 880 service framework, YANG data models described in 881 [consumer-facing-inf-dm], [nsf-facing-inf-dm], and 882 [registration-inf-dm] can be used as Consumer-Facing Interface, NSF- 883 Facing Interface, and Registration Interface, respectively, along 884 with RESTCONF [RFC8040] and NETCONF [RFC6241]. 886 +--------------------+ 887 +-------------------------------------------+ | ---------------- | 888 | I2NSF User (OSS/BSS) | | | NFV | | 889 +------+------------------------------------+ | | Orchestrator +-+ | 890 | Consumer-Facing Interface | -----+---------- | | 891 +------|------------------------------------+ | | | | 892 | -----+---------- (a) ----------------- | | ----+----- | | 893 | | Security +-------+ Developer's | | | | | | | 894 | |Controller(EM)| |Mgmt System(EM)| +-(b)-+ VNFM(s)| | | 895 | -----+---------- ----------------- | | | | | | 896 | | NSF-Facing Interface | | ----+----- | | 897 | ----+----- ----+----- ----+----- | | | | | 898 | |NSF(VNF)| |NSF(VNF)| |NSF(VNF)| | | | | | 899 | ----+----- ----+----- ----+----- | | | | | 900 | | | | | | | | | 901 +------|-------------|-------------|--------+ | | | | 902 | | | | | | | 903 +------+-------------+-------------+--------+ | | | | 904 | NFV Infrastructure (NFVI) | | | | | 905 | ----------- ----------- ----------- | | | | | 906 | | Virtual | | Virtual | | Virtual | | | | | | 907 | | Compute | | Storage | | Network | | | | | | 908 | ----------- ----------- ----------- | | ----+----- | | 909 | +---------------------------------------+ | | | | | | 910 | | Virtualization Layer | +-----+ VIM(s) +------+ | 911 | +---------------------------------------+ | | | | | 912 | +---------------------------------------+ | | ---------- | 913 | | ----------- ----------- ----------- | | | | 914 | | | Compute | | Storage | | Network | | | | | 915 | | | Hardware| | Hardware| | Hardware| | | | | 916 | | ----------- ----------- ----------- | | | | 917 | | Hardware Resources | | | NFV Management | 918 | +---------------------------------------+ | | and Orchestration | 919 | | | (MANO) | 920 +-------------------------------------------+ +--------------------+ 921 (a) = Registration Interface 922 (b) = Ve-Vnfm Interface 924 Figure 7: I2NSF Framework Implementation with respect to the NFV 925 Reference Architectural Framework 927 8. I2NSF Framework with NFV 929 This section discusses the implementation of the I2NSF framework 930 using Network Functions Virtualization (NFV). 932 NFV is a promising technology for improving the elasticity and 933 efficiency of network resource utilization. In NFV environments, 934 NSFs can be deployed in the forms of software-based virtual instances 935 rather than physical appliances. Virtualizing NSFs makes it possible 936 to rapidly and flexibly respond to the amount of service requests by 937 dynamically increasing or decreasing the number of NSF instances. 938 Moreover, NFV technology facilitates flexibly including or excluding 939 NSFs from multiple security solution vendors according to the changes 940 on security requirements. In order to take advantages of the NFV 941 technology, the I2NSF framework can be implemented on top of an NFV 942 infrastructure as show in Figure 7. 944 Figure 7 shows an I2NSF framework implementation based on the NFV 945 reference architecture that the European Telecommunications Standards 946 Institute (ETSI) defines [ETSI-NFV]. The NSFs are deployed as VNFs 947 in Figure 7. The Developer's Management System (DMS) in the I2NSF 948 framework is responsible for registering capability information of 949 NSFs into the Security Controller. However, those NSFs are created 950 or removed by a virtual network function manager (VNFM) in the NFV 951 MANO that performs the lifecycle management of VNFs. Note that the 952 lifecycle management of VNFs is out of scope for I2NSF. The Security 953 Controller controls and monitors the configurations (e.g., function 954 parameters and security policy rules) of VNFs via the NSF-Facing 955 Interface along with the NSF monitoring capability 956 [nsf-facing-inf-dm][nsf-monitoring-dm]. Both the DMS and Security 957 Controller can be implemented as the Element Managements (EMs) in the 958 NFV architecture. Finally, the I2NSF User can be implemented as OSS/ 959 BSS (Operational Support Systems/Business Support Systems) in the NFV 960 architecture that provides interfaces for users in the NFV system. 962 The operation procedure in the I2NSF framework based on the NFV 963 architecture is as follows: 965 1. The VNFM has a set of virtual machine (VM) images of NSFs, and 966 each VM image can be used to create an NSF instance that provides 967 a set of security capabilities. The DMS initially registers a 968 mapping table of the ID of each VM image and the set of 969 capabilities that can be provided by an NSF instance created from 970 the VM image into the Security Controller. 972 2. If the Security Controller does not have any instantiated NSF 973 that has the set of capabilities required to meet the security 974 requirements from users, it searches the mapping table 975 (registered by the DMS) for the VM image ID corresponding to the 976 required set of capabilities. 978 3. The Security Controller requests the DMS to instantiate an NSF 979 with the VM image ID via VNFM. 981 4. When receiving the instantiation request, the VNFM first asks the 982 NFV orchestrator for the permission required to create the NSF 983 instance, requests the VIM to allocate resources for the NSF 984 instance, and finally creates the NSF instance based on the 985 allocated resources. 987 5. Once the NSF instance has been created by the VNFM, the DMS 988 performs the initial configurations of the NSF instance and then 989 notifies the Security Controller of the NSF instance. 991 6. After being notified of the created NSF instance, the Security 992 Controller delivers low-level security policy rules to the NSF 993 instance for policy enforcement. 995 We can conclude that the I2NSF framework can be implemented based on 996 the NFV architecture framework. Note that the registration of the 997 capabilities of NSFs is performed through the Registration Interface 998 and the lifecycle management for NSFs (VNFs) is performed through the 999 Ve-Vnfm interface between the DMS and VNFM, as shown in Figure 7. 1001 9. Security Considerations 1003 The same security considerations for the I2NSF framework [RFC8329] 1004 are applicable to this document. 1006 This document shares all the security issues of SDN that are 1007 specified in the "Security Considerations" section of [ITU-T.Y.3300]. 1009 The role of the DMS is to provide an I2NSF system with the software 1010 packages or images for NSF execution. The DMS must not access NSFs 1011 in activated status. An inside attacker or a supply chain attacker 1012 at the DMS can seriously weaken the I2NSF system's security. A 1013 malicious DMS is relevant to an insider attack, and a compromised DMS 1014 is relevant to a supply chain attack. A malicious (or compromised) 1015 DMS could register an NSF of its choice in response to a capability 1016 request by the Security Controller. As a result, a malicious DMS can 1017 attack the I2NSF system by providing malicious NSFs with arbitrary 1018 capabilities to include potentially controlling those NSFs in real 1019 time. An unwitting DMS could be compromised and the infrastructure 1020 of the DMS could be coerced into distributing modified NSFs as well. 1022 To deal with these types of threats, an I2NSF system should not use 1023 NSFs from an untrusted DMS or without prior testing. The practices 1024 by which these packages are downloaded and loaded into the system are 1025 out of scope for I2NSF. 1027 I2NSF system operators should audit and monitor interactions with 1028 DMSs. Additionally, the operators should monitor the running NSFs 1029 through the I2NSF NSF Monitoring Interface [nsf-monitoring-dm] as 1030 part of the I2NSF NSF-Facing Interface. Note that the mechanics for 1031 monitoring the DMSs are out of scope for I2NSF. 1033 10. Acknowledgments 1035 This work was supported by Institute of Information & Communications 1036 Technology Planning & Evaluation (IITP) grant funded by the Korea 1037 MSIT (Ministry of Science and ICT) (R-20160222-002755, Cloud based 1038 Security Intelligence Technology Development for the Customized 1039 Security Service Provisioning). 1041 This work has been partially supported by the European Commission 1042 under Horizon 2020 grant agreement no. 700199 "Securing against 1043 intruders and other threats through a NFV-enabled environment 1044 (SHIELD)". This support does not imply endorsement. 1046 11. Contributors 1048 I2NSF is a group effort. I2NSF has had a number of contributing 1049 authors. The following are considered co-authors: 1051 o Hyoungshick Kim (Sungkyunkwan University) 1053 o Jinyong Tim Kim (Sungkyunkwan University) 1055 o Hyunsik Yang (Soongsil University) 1057 o Younghan Kim (Soongsil University) 1059 o Jung-Soo Park (ETRI) 1061 o Se-Hui Lee (Korea Telecom) 1063 o Mohamed Boucadair (Orange) 1065 12. References 1067 12.1. Normative References 1069 [AVANT-GUARD] 1070 Shin, S., Yegneswaran, V., Porras, P., and G. Gu, "AVANT- 1071 GUARD: Scalable and Vigilant Switch Flow Management in 1072 Software-Defined Networks", ACM CCS, November 2013. 1074 [consumer-facing-inf-dm] 1075 Jeong, J., Kim, E., Ahn, T., Kumar, R., and S. Hares, 1076 "I2NSF Consumer-Facing Interface YANG Data Model", draft- 1077 ietf-i2nsf-consumer-facing-interface-dm-06 (work in 1078 progress), July 2019. 1080 [dots-architecture] 1081 Mortensen, A., Reddy, T., Andreasen, F., Teague, N., and 1082 R. Compton, "Distributed-Denial-of-Service Open Threat 1083 Signaling (DOTS) Architecture", draft-ietf-dots- 1084 architecture-14 (work in progress), May 2019. 1086 [ETSI-NFV] 1087 "Network Functions Virtualisation (NFV); Architectural 1088 Framework", Available: 1089 https://www.etsi.org/deliver/etsi_gs/ 1090 nfv/001_099/002/01.01.01_60/gs_nfv002v010101p.pdf, October 1091 2013. 1093 [ITU-T.Y.3300] 1094 "Framework of Software-Defined Networking", 1095 Available: https://www.itu.int/rec/T-REC-Y.3300-201406-I, 1096 June 2014. 1098 [NFV-Terminology] 1099 "Network Functions Virtualisation (NFV); Terminology for 1100 Main Concepts in NFV", Available: 1101 https://www.etsi.org/deliver/etsi_gs/ 1102 NFV/001_099/003/01.02.01_60/gs_nfv003v010201p.pdf, 1103 December 2014. 1105 [nsf-facing-inf-dm] 1106 Kim, J., Jeong, J., Park, J., Hares, S., and Q. Lin, 1107 "I2NSF Network Security Function-Facing Interface YANG 1108 Data Model", draft-ietf-i2nsf-nsf-facing-interface-dm-07 1109 (work in progress), July 2019. 1111 [nsf-monitoring-dm] 1112 Jeong, J., Chung, C., Hares, S., Xia, L., and H. Birkholz, 1113 "I2NSF NSF Monitoring YANG Data Model", draft-ietf-i2nsf- 1114 nsf-monitoring-data-model-01 (work in progress), July 1115 2019. 1117 [ONF-SDN-Architecture] 1118 "SDN Architecture (Issue 1.1)", Available: 1119 https://www.opennetworking.org/wp- 1120 content/uploads/2014/10/TR- 1121 521_SDN_Architecture_issue_1.1.pdf, June 2016. 1123 [registration-inf-dm] 1124 Hyun, S., Jeong, J., Roh, T., Wi, S., and J. Park, "I2NSF 1125 Registration Interface YANG Data Model", draft-ietf-i2nsf- 1126 registration-interface-dm-05 (work in progress), July 1127 2019. 1129 [RFC6020] Bjorklund, M., "YANG - A Data Modeling Language for the 1130 Network Configuration Protocol (NETCONF)", RFC 6020, 1131 October 2010. 1133 [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. 1134 Bierman, "Network Configuration Protocol (NETCONF)", 1135 RFC 6241, June 2011. 1137 [RFC7149] Boucadair, M. and C. Jacquenet, "Software-Defined 1138 Networking: A Perspective from within a Service Provider 1139 Environment", RFC 7149, March 2014. 1141 [RFC7665] Halpern, J. and C. Pignataro, "Service Function Chaining 1142 (SFC) Architecture", RFC 7665, October 2015. 1144 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF 1145 Protocol", RFC 8040, January 2017. 1147 [RFC8192] Hares, S., Lopez, D., Zarny, M., Jacquenet, C., Kumar, R., 1148 and J. Jeong, "Interface to Network Security Functions 1149 (I2NSF): Problem Statement and Use Cases", RFC 8192, July 1150 2017. 1152 [RFC8300] Quinn, P., Elzur, U., and C. Pignataro, "Network Service 1153 Header (NSH)", RFC 8300, January 2018. 1155 [RFC8329] Lopez, D., Lopez, E., Dunbar, L., Strassner, J., and R. 1156 Kumar, "Framework for Interface to Network Security 1157 Functions", RFC 8329, February 2018. 1159 [RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol 1160 Version 1.3", RFC 8446, August 2018. 1162 [RFC8612] Mortensen, A., Reddy, T., and R. Moskowitz, "DDoS Open 1163 Threat Signaling (DOTS) Requirements", RFC 8612, May 2019. 1165 12.2. Informative References 1167 [ETSI-NFV-MANO] 1168 "Network Functions Virtualisation (NFV); Management and 1169 Orchestration", Available: 1170 https://www.etsi.org/deliver/etsi_gs/nfv- 1171 man/001_099/001/01.01.01_60/gs_nfv-man001v010101p.pdf, 1172 December 2014. 1174 [i2nsf-terminology] 1175 Hares, S., Strassner, J., Lopez, D., Xia, L., and H. 1176 Birkholz, "Interface to Network Security Functions (I2NSF) 1177 Terminology", draft-ietf-i2nsf-terminology-08 (work in 1178 progress), July 2019. 1180 [ITU-T.X.800] 1181 "Security Architecture for Open Systems Interconnection 1182 for CCITT Applications", March 1991. 1184 [opsawg-firewalls] 1185 Baker, F. and P. Hoffman, "On Firewalls in Internet 1186 Security", draft-ietf-opsawg-firewalls-01 (work in 1187 progress), October 2012. 1189 [policy-translation] 1190 Jeong, J., Yang, J., Chung, C., and J. Kim, "Security 1191 Policy Translation in Interface to Network Security 1192 Functions", draft-yang-i2nsf-security-policy- 1193 translation-04 (work in progress), July 2019. 1195 [tls-esni] 1196 Rescorla, E., Oku, K., Sullivan, N., and C. Wood, 1197 "Encrypted Server Name Indication for TLS 1.3", draft- 1198 ietf-tls-esni-04 (work in progress), July 2019. 1200 [VNF-ONBOARDING] 1201 "VNF Onboarding", Available: 1202 https://wiki.opnfv.org/display/mano/VNF+Onboarding, 1203 November 2016. 1205 Appendix A. Changes from draft-ietf-i2nsf-applicability-17 1207 The following changes have been made from draft-ietf-i2nsf- 1208 applicability-17: 1210 o In Section 4, a high-level security policy XML file in Figure 2 1211 and the corresponding low-level security policy XML file Figure 3 1212 are constructed using the Consumer-Facing Interface data model and 1213 the NSF-Facing data model, respectively. 1215 o For the applicability of I2NSF to the real world, Section 5 is 1216 added to support the Intent-based Security Services using I2NSF. 1217 This section explains the security policy translation based on an 1218 I2NSF User's intents on the required security services. Figure 4 1219 shows the archiecture and procedure of the I2NSF security policy 1220 translator. 1222 Authors' Addresses 1224 Jaehoon Paul Jeong 1225 Department of Computer Science and Engineering 1226 Sungkyunkwan University 1227 2066 Seobu-Ro, Jangan-Gu 1228 Suwon, Gyeonggi-Do 16419 1229 Republic of Korea 1231 Phone: +82 31 299 4957 1232 Fax: +82 31 290 7996 1233 EMail: pauljeong@skku.edu 1234 URI: http://iotlab.skku.edu/people-jaehoon-jeong.php 1236 Sangwon Hyun 1237 Department of Computer Engineering 1238 Myongji University 1239 116 Myongji-ro, Cheoin-gu 1240 Yongin 17058 1241 Republic of Korea 1243 Phone: +82 62 230 7473 1244 EMail: shyun@chosun.ac.kr 1245 Tae-Jin Ahn 1246 Korea Telecom 1247 70 Yuseong-Ro, Yuseong-Gu 1248 Daejeon 305-811 1249 Republic of Korea 1251 Phone: +82 42 870 8409 1252 EMail: taejin.ahn@kt.com 1254 Susan Hares 1255 Huawei 1256 7453 Hickory Hill 1257 Saline, MI 48176 1258 USA 1260 Phone: +1-734-604-0332 1261 EMail: shares@ndzh.com 1263 Diego R. Lopez 1264 Telefonica I+D 1265 Jose Manuel Lara, 9 1266 Seville 41013 1267 Spain 1269 Phone: +34 682 051 091 1270 EMail: diego.r.lopez@telefonica.com