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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Outdated reference: A later version (-11) exists of draft-ietf-uta-tls-bcp-09 ** Obsolete normative reference: RFC 5246 (Obsoleted by RFC 8446) ** Obsolete normative reference: RFC 6125 (Obsoleted by RFC 9525) -- Obsolete informational reference (is this intentional?): RFC 4742 (Obsoleted by RFC 6242) -- Obsolete informational reference (is this intentional?): RFC 5539 (Obsoleted by RFC 7589) Summary: 2 errors (**), 0 flaws (~~), 2 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 NETCONF Working Group M. Badra 3 Internet-Draft Zayed University 4 Obsoletes: 5539 (if approved) A. Luchuk 5 Intended status: Standards Track SNMP Research, Inc. 6 Expires: August 16, 2015 J. Schoenwaelder 7 Jacobs University Bremen 8 February 12, 2015 10 Using the NETCONF Protocol over Transport Layer Security (TLS) with 11 Mutual X.509 Authentication 12 draft-ietf-netconf-rfc5539bis-09 14 Abstract 16 The Network Configuration Protocol (NETCONF) provides mechanisms to 17 install, manipulate, and delete the configuration of network devices. 18 This document describes how to use the Transport Layer Security (TLS) 19 protocol with mutual X.509 authentication to secure the exchange of 20 NETCONF messages. This revision of RFC 5539 documents the new 21 message framing used by NETCONF 1.1 and it obsoletes RFC 5539. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on August 16, 2015. 40 Copyright Notice 42 Copyright (c) 2015 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Connection Initiation . . . . . . . . . . . . . . . . . . . . 3 59 3. Message Framing . . . . . . . . . . . . . . . . . . . . . . . 3 60 4. Connection Closure . . . . . . . . . . . . . . . . . . . . . 3 61 5. Certificate Validation . . . . . . . . . . . . . . . . . . . 4 62 6. Server Identity . . . . . . . . . . . . . . . . . . . . . . . 4 63 7. Client Identity . . . . . . . . . . . . . . . . . . . . . . . 4 64 8. Cipher Suites . . . . . . . . . . . . . . . . . . . . . . . . 6 65 9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 66 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 67 11. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 7 68 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 69 12.1. Normative References . . . . . . . . . . . . . . . . . . 8 70 12.2. Informative References . . . . . . . . . . . . . . . . . 8 71 Appendix A. Changes from RFC 5539 . . . . . . . . . . . . . . . 9 72 Appendix B. Change Log . . . . . . . . . . . . . . . . . . . . . 9 73 B.1. draft-ietf-netconf-rfc5539bis-07 . . . . . . . . . . . . 9 74 B.2. draft-ietf-netconf-rfc5539bis-06 . . . . . . . . . . . . 9 75 B.3. draft-ietf-netconf-rfc5539bis-05 . . . . . . . . . . . . 10 76 B.4. draft-ietf-netconf-rfc5539bis-04 . . . . . . . . . . . . 10 77 B.5. draft-ietf-netconf-rfc5539bis-03 . . . . . . . . . . . . 10 78 B.6. draft-ietf-netconf-rfc5539bis-02 . . . . . . . . . . . . 10 79 B.7. draft-ietf-netconf-rfc5539bis-00 . . . . . . . . . . . . 11 80 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 82 1. Introduction 84 The NETCONF protocol [RFC6241] defines a mechanism through which a 85 network device can be managed. NETCONF is connection-oriented, 86 requiring a persistent connection between peers. This connection 87 must provide integrity, confidentiality, peer authentication, and 88 reliable, sequenced data delivery. 90 This document defines how NETCONF messages can be exchanged over 91 Transport Layer Security (TLS) [RFC5246]. Implementations MUST 92 support mutual TLS certificate-based authentication [RFC5246]. This 93 assures the NETCONF server of the identity of the principal who 94 wishes to manipulate the management information. It also assures the 95 NETCONF client of the identity of the server for which it wishes to 96 manipulate the management information. 98 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 99 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 100 document are to be interpreted as described in [RFC2119]. 102 2. Connection Initiation 104 The peer acting as the NETCONF client MUST act as the TLS client. 105 The TLS client actively opens the TLS connection and the TLS server 106 passively listens for the incoming TLS connections. The well-known 107 TCP port number 6513 is used by NETCONF servers to listen for TCP 108 connections established by NETCONF over TLS clients. The TLS client 109 MUST send the TLS ClientHello message to begin the TLS handshake. 110 Once the TLS handshake has finished, the client and the server MAY 111 begin to exchange NETCONF messages. Client and server identity 112 verification is done before the NETCONF message is sent. 113 This means that the identity verification is completed before the 114 NETCONF session is started. 116 3. Message Framing 118 All NETCONF messages MUST be sent as TLS "application data". It is 119 possible that multiple NETCONF messages be contained in one TLS 120 record, or that a NETCONF message be transferred in multiple TLS 121 records. 123 The previous version [RFC5539] of this document used the framing 124 sequence defined in [RFC4742], under the assumption that it could not 125 be found in well-formed XML documents. However, this assumption is 126 not correct [RFC6242]. In order to solve this problem, this document 127 adopts the framing protocol defined in [RFC6242] as follows: 129 The NETCONF message MUST be followed by the character 130 sequence ]]>]]>. Upon reception of the message, the peers 131 inspect the announced capabilities. If the :base:1.1 capability is 132 advertised by both peers, the chunked framing mechanism defined in 133 Section 4.2 of [RFC6242] is used for the remainder of the NETCONF 134 session. Otherwise, the old end-of-message-based mechanism (see 135 Section 4.3 of [RFC6242]) is used. 137 4. Connection Closure 139 A NETCONF server will process NETCONF messages from the NETCONF 140 client in the order in which they are received. A NETCONF session is 141 closed using the operation. When the NETCONF server 142 processes a operation, the NETCONF server SHALL 143 respond and close the TLS session as described in Section 7.2.1 of 144 [RFC5246]. 146 5. Certificate Validation 148 Both peers MUST use X.509 certificate path validation [RFC5280] to 149 verify the integrity of the certificate presented by the peer. The 150 presented X.509 certificate may also be considered valid if it 151 matches a locally configured certificate fingerprint. If X.509 152 certificate path validation fails and the presented X.509 certificate 153 does not match a locally configured certificate fingerprint, the 154 connection MUST be terminated as defined in [RFC5246]. 156 6. Server Identity 158 The NETCONF client MUST check the identity of the server according to 159 Section 6 of [RFC6125]. 161 7. Client Identity 163 The NETCONF server MUST verify the identity of the NETCONF client to 164 ensure that the incoming request to establish a NETCONF session is 165 legitimate before the NETCONF session is started. 167 The NETCONF protocol [RFC6241] requires that the transport protocol's 168 authentication process results in an authenticated NETCONF client 169 identity whose permissions are known to the server. The 170 authenticated identity of a client is commonly referred to as the 171 NETCONF username. The following algorithm is used by the NETCONF 172 server to derive a NETCONF username from a certificate. (Note that 173 the algorithm below is the same as the one described in the SNMP-TLS- 174 TM-MIB MIB module defined in [RFC6353] and in the ietf-x509-cert-to- 175 name YANG module defined in [RFC7407].) 177 (a) The server maintains an ordered list of mappings of certificates 178 to NETCONF usernames. Each list entry contains 180 * a certificate fingerprint (used for matching the presented 181 certificate), 183 * a map type (indicates how the NETCONF username is derived 184 from the certificate), and 186 * optional auxiliary data (used to carry a NETCONF username if 187 the map type indicates the user name is explicitly 188 configured). 190 (b) The NETCONF username is derived by considering each list entry 191 in order. The fingerprint member of the current list entry 192 determines whether the current list entry is a match: 194 1. If the list entry's fingerprint value matches the 195 fingerprint of the presented certificate, then consider the 196 list entry as a successful match. 198 2. If the list entry's fingerprint value matches that of a 199 locally held copy of a trusted CA certificate, and that CA 200 certificate was part of the CA certificate chain to the 201 presented certificate, then consider the list entry as a 202 successful match. 204 (c) Once a matching list entry has been found, the map type of the 205 current list entry is used to determine how the username 206 associated with the certificate should be determined. Possible 207 mapping options are: 209 A. The username is taken from the auxiliary data of the current 210 list entry. This means the username is explicitely 211 configured (map type 'specified'). 213 B. The subjectAltName's rfc822Name field is mapped to the 214 username (map type 'san-rfc822-name'). The local part of 215 the rfc822Name is used unaltered but the host-part of the 216 name must be converted to lowercase. 218 C. The subjectAltName's dNSName is mapped to the username (map 219 type 'san-dns-name'). The characters of the dNSName are 220 converted to lowercase. 222 D. The subjectAltName's iPAddress is mapped to the username 223 (map type 'san-ip-address'). IPv4 addresses are converted 224 into decimal-dotted quad notation (e.g., '192.0.2.1'). IPv6 225 addresses are converted into a 32-character all lowercase 226 hexadecimal string without any colon separators. 228 E. Any of the subjectAltName's rfc822Name, dNSName, iPAddress 229 is mapped to the username (map type 'san-any'). The first 230 matching subjectAltName value found in the certificate of 231 the above types MUST be used when deriving the name. 233 F. The certificate's CommonName is mapped to the username (map 234 type 'common-name'). The CommonName is converted to UTF-8 235 encoding. The usage of CommonNames is deprecated and users 236 are encouraged to use subjectAltName mapping methods 237 instead. 239 (d) If it is impossible to determine a username from the list 240 entry's data combined with the data presented in the 241 certificate, then additional list entries MUST be searched 242 looking for another potential match. Similarily, if the 243 username does not comply to the NETCONF requirements on 244 usernames [RFC6241] (i.e., the username is not representable in 245 XML), then additional list entries MUST be searched looking for 246 another potential match. If there are no further list entries, 247 the TLS session MUST be terminated. 249 The username provided by the NETCONF over TLS implementation will be 250 made available to the NETCONF message layer as the NETCONF username 251 without modification. 253 8. Cipher Suites 255 Implementations MUST support TLS 1.2 [RFC5246] and are REQUIRED to 256 support the mandatory-to-implement cipher suite. Implementations MAY 257 implement additional TLS cipher suites that provide mutual 258 authentication [RFC5246] and confidentiality as required by NETCONF 259 [RFC6241]. Implementations SHOULD follow the recommendations given 260 in [I-D.ietf-uta-tls-bcp]. 262 9. Security Considerations 264 NETCONF is used to access configuration and state information and to 265 modify configuration information, so the ability to access this 266 protocol should be limited to users and systems that are authorized 267 to view the NETCONF server's configuration and state or to modify the 268 NETCONF server's configuration. 270 Configuration or state data may include sensitive information, such 271 as usernames or security keys. So, NETCONF requires communications 272 channels that provide strong encryption for data privacy. This 273 document defines a NETCONF over TLS mapping that provides for support 274 of strong encryption and authentication. The security considerations 275 for TLS [RFC5246] and NETCONF [RFC6241] apply here as well. 277 NETCONF over TLS requires mutual authentication. Neither side should 278 establish a NETCONF over TLS connection with an unknown, unexpected, 279 or incorrect identity on the opposite side. This document does not 280 support third-party authentication (e.g., backend Authentication, 281 Authorization, and Accounting (AAA) servers) due to the fact that TLS 282 does not specify this way of authentication and that NETCONF depends 283 on the transport protocol for the authentication service. If third- 284 party authentication is needed, the SSH transport can be used. 286 RFC 5539 assumes that the end-of-message (EOM) sequence, ]]>]]>, 287 cannot appear in any well-formed XML document, which turned out to be 288 mistaken. The EOM sequence can cause operational problems and open 289 space for attacks if sent deliberately in NETCONF messages. It is 290 however believed that the associated threat is not very high. This 291 document still uses the EOM sequence for the initial message 292 to avoid incompatibility with existing implementations. When both 293 peers implement :base:1.1 capability, a proper framing protocol 294 (chunked framing mechanism; see Section 3) is used for the rest of 295 the NETCONF session, to avoid injection attacks. 297 10. IANA Considerations 299 Based on the previous version of this document, RFC 5539, IANA has 300 assigned a TCP port number (6513) in the "Registered Port Numbers" 301 range with the service name "netconf-tls". This port will be the 302 default port for NETCONF over TLS, as defined in Section 2. Below is 303 the registration template following the rules in [RFC6335]. 305 Service Name: netconf-tls 306 Transport Protocol(s): TCP 307 Assignee: IESG 308 Contact: IETF Chair 309 Description: NETCONF over TLS 310 Reference: RFC XXXX 311 Port Number: 6513 313 [[CREF1: RFC Editor: Please replace XXXX above with the allocated RFC 314 number and remove this comment. --JS]] 316 11. Acknowledgements 318 The authors like to acknowledge Martin Bjorklund, Olivier Coupelon, 319 Mehmet Ersue, Miao Fuyou, Ibrahim Hajjeh, David Harrington, Alfred 320 Hoenes, Simon Josefsson, Tom Petch, Eric Rescorla, Dan Romascanu, 321 Kent Watsen, Bert Wijnen and the NETCONF mailing list members for 322 their comments on this document. Charlie Kaufman, Pasi Eronen, and 323 Tim Polk provided a thorough review of previous versions of this 324 document. 326 Juergen Schoenwaelder was partly funded by Flamingo, a Network of 327 Excellence project (ICT-318488) supported by the European Commission 328 under its Seventh Framework Programme. 330 12. References 331 12.1. Normative References 333 [I-D.ietf-uta-tls-bcp] 334 Sheffer, Y., Holz, R., and P. Saint-Andre, 335 "Recommendations for Secure Use of TLS and DTLS", draft- 336 ietf-uta-tls-bcp-09 (work in progress), February 2015. 338 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 339 Requirement Levels", BCP 14, RFC 2119, March 1997. 341 [RFC5246] Dierks, T. and E. Rescorla, "The Transport Layer Security 342 (TLS) Protocol Version 1.2", RFC 5246, August 2008. 344 [RFC5280] Cooper, D., Santesson, S., Farrell, S., Boeyen, S., 345 Housley, R., and W. Polk, "Internet X.509 Public Key 346 Infrastructure Certificate and Certificate Revocation List 347 (CRL) Profile", RFC 5280, May 2008. 349 [RFC6125] Saint-Andre, P. and J. Hodges, "Representation and 350 Verification of Domain-Based Application Service Identity 351 within Internet Public Key Infrastructure Using X.509 352 (PKIX) Certificates in the Context of Transport Layer 353 Security (TLS)", RFC 6125, March 2011. 355 [RFC6241] Enns, R., Bjorklund, M., Schoenwaelder, J., and A. 356 Bierman, "Network Configuration Protocol (NETCONF)", RFC 357 6241, June 2011. 359 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure 360 Shell (SSH)", RFC 6242, June 2011. 362 [RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S. 363 Cheshire, "Internet Assigned Numbers Authority (IANA) 364 Procedures for the Management of the Service Name and 365 Transport Protocol Port Number Registry", BCP 165, RFC 366 6335, August 2011. 368 12.2. Informative References 370 [RFC4742] Wasserman, M. and T. Goddard, "Using the NETCONF 371 Configuration Protocol over Secure SHell (SSH)", RFC 4742, 372 December 2006. 374 [RFC5539] Badra, M., "NETCONF over Transport Layer Security (TLS)", 375 RFC 5539, May 2009. 377 [RFC6353] Hardaker, W., "Transport Layer Security (TLS) Transport 378 Model for the Simple Network Management Protocol (SNMP)", 379 STD 78, RFC 6353, July 2011. 381 [RFC7407] Bjorklund, M. and J. Schoenwaelder, "A YANG Data Model for 382 SNMP Configuration", RFC 7407, December 2014. 384 Appendix A. Changes from RFC 5539 386 This section summarizes major changes between this document and RFC 387 5539. 389 o Documented that NETCONF over TLS uses the new message framing if 390 both peers support the :base:1.1 capability. 392 o Removed redundant text that can be found in the TLS and NETCONF 393 specifications and restructured the text. Alignment with 394 [RFC6125]. 396 o Added a high-level description how NETCONF usernames are derived 397 from certificates. 399 o Removed the reference to BEEP. 401 Appendix B. Change Log 403 [[CREF2: RFC Editor: Please remove this appendix before publication. 404 --JS]] 406 B.1. draft-ietf-netconf-rfc5539bis-07 408 o Limited the scope of the document to TLS with mutual X.509 409 authentication. 411 o Added a high-level description how NETCONF usernames are extracted 412 from certificates. 414 o Editorial changes 416 B.2. draft-ietf-netconf-rfc5539bis-06 418 o Removed all call-home related text. 420 o Removed redundant text as discussed at the Toronto IETF meeting. 422 B.3. draft-ietf-netconf-rfc5539bis-05 424 o Removed the YANG configuration data model since it became a 425 separate document. 427 o Added reference to RFC 3234 plus editorial updates. 429 B.4. draft-ietf-netconf-rfc5539bis-04 431 o Added the applicability statement proposed by Stephen Hanna. 433 o Added call-home configuration objects and a tls-call-home feature. 435 o Rewrote the text such that the role swap happens right after the 436 TCP connection has been established. 438 B.5. draft-ietf-netconf-rfc5539bis-03 440 o Added support for call home (allocation of a new port number, 441 rewrote text to allow a NETCONF client to be a TLS server and a 442 NETCONF server to be a TLS client). 444 o Merged sections 2 and 3 into a new section 2 and restructured the 445 text. 447 o Extended the IANA considerations section. 449 o Using the cert-to-name mapping grouping from the SNMP 450 configuration data model and updated the examples. 452 o Creating an extensible set of YANG (sub)modules for NETCONF 453 following the (sub)module structure of the SNMP configuration 454 model. 456 B.6. draft-ietf-netconf-rfc5539bis-02 458 o Addressed remaining issues identified at IETF 85 460 * Harmonized the cert-maps container of the YANG module in this 461 draft with the tlstm container in the ietf-snmp-tls sub-module 462 specified in draft-ietf-netmod-snmp-cfg. Replaced the children 463 of the cert-maps container with the children copied from the 464 tlstm container of the ietf-snmp-tls sub-module. 466 * Added an overview of data model in the ietf-netconf-tls YANG 467 module. 469 * Added example configurations. 471 o Addessed issues posted on NETCONF WG E-mail list. 473 o Deleted the superfluous tls container that was directly below the 474 netconf-config container. 476 o Added a statement to the text indicating that support for mapping 477 X.509 certificates to NETCONF usernames is optional. This is 478 analogous to existing text indicating that support for mapping 479 pre-shared keys to NETCONF usernames is optional. Resource- 480 constrained systems now can omit support for mapping X.509 481 certificates to NETCONF usernames and still comply with this 482 specification. 484 o Clarified the document structure by promoting the sections of the 485 document related to the data model. 487 o Updated author's addresses. 489 B.7. draft-ietf-netconf-rfc5539bis-00 491 o Remove the reference to BEEP. 493 o Rename host-part to domain-part in the description of RFC822. 495 Authors' Addresses 497 Mohamad Badra 498 Zayed University 500 Email: mbadra@gmail.com 502 Alan Luchuk 503 SNMP Research, Inc. 504 3001 Kimberlin Heights Road 505 Knoxville, TN 37920 506 USA 508 Phone: +1 865 573 1434 509 Email: luchuk@snmp.com 510 URI: http://www.snmp.com/ 511 Juergen Schoenwaelder 512 Jacobs University Bremen 513 Campus Ring 1 514 28759 Bremen 515 Germany 517 Phone: +49 421 200 3587 518 Email: j.schoenwaelder@jacobs-university.de 519 URI: http://www.jacobs-university.de/