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2 NETCONF Working Group K. Watsen
3 Internet-Draft Juniper Networks
4 Intended status: Standards Track G. Wu
5 Expires: December 6, 2018 Cisco Systems
6 June 4, 2018
8 YANG Groupings for SSH Clients and SSH Servers
9 draft-ietf-netconf-ssh-client-server-06
11 Abstract
13 This document defines three YANG modules: the first defines groupings
14 for a generic SSH client, the second defines groupings for a generic
15 SSH server, and the third defines common identities and groupings
16 used by both the client and the server. It is intended that these
17 groupings will be used by applications using the SSH protocol.
19 Editorial Note (To be removed by RFC Editor)
21 This draft contains many placeholder values that need to be replaced
22 with finalized values at the time of publication. This note
23 summarizes all of the substitutions that are needed. No other RFC
24 Editor instructions are specified elsewhere in this document.
26 This document contains references to other drafts in progress, both
27 in the Normative References section, as well as in body text
28 throughout. Please update the following references to reflect their
29 final RFC assignments:
31 o I-D.ietf-netconf-trust-anchors
33 o I-D.ietf-netconf-keystore
35 Artwork in this document contains shorthand references to drafts in
36 progress. Please apply the following replacements:
38 o "XXXX" --> the assigned RFC value for this draft
40 o "YYYY" --> the assigned RFC value for I-D.ietf-netconf-trust-
41 anchors
43 o "ZZZZ" --> the assigned RFC value for I-D.ietf-netconf-keystore
45 Artwork in this document contains placeholder values for the date of
46 publication of this draft. Please apply the following replacement:
48 o "2018-06-04" --> the publication date of this draft
49 The following Appendix section is to be removed prior to publication:
51 o Appendix A. Change Log
53 Status of This Memo
55 This Internet-Draft is submitted in full conformance with the
56 provisions of BCP 78 and BCP 79.
58 Internet-Drafts are working documents of the Internet Engineering
59 Task Force (IETF). Note that other groups may also distribute
60 working documents as Internet-Drafts. The list of current Internet-
61 Drafts is at https://datatracker.ietf.org/drafts/current/.
63 Internet-Drafts are draft documents valid for a maximum of six months
64 and may be updated, replaced, or obsoleted by other documents at any
65 time. It is inappropriate to use Internet-Drafts as reference
66 material or to cite them other than as "work in progress."
68 This Internet-Draft will expire on December 6, 2018.
70 Copyright Notice
72 Copyright (c) 2018 IETF Trust and the persons identified as the
73 document authors. All rights reserved.
75 This document is subject to BCP 78 and the IETF Trust's Legal
76 Provisions Relating to IETF Documents
77 (https://trustee.ietf.org/license-info) in effect on the date of
78 publication of this document. Please review these documents
79 carefully, as they describe your rights and restrictions with respect
80 to this document. Code Components extracted from this document must
81 include Simplified BSD License text as described in Section 4.e of
82 the Trust Legal Provisions and are provided without warranty as
83 described in the Simplified BSD License.
85 Table of Contents
87 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
88 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
89 3. The SSH Client Model . . . . . . . . . . . . . . . . . . . . 4
90 3.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 4
91 3.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 6
92 3.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 9
93 4. The SSH Server Model . . . . . . . . . . . . . . . . . . . . 12
94 4.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 12
95 4.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 14
96 4.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 17
98 5. The SSH Common Model . . . . . . . . . . . . . . . . . . . . 20
99 5.1. Tree Diagram . . . . . . . . . . . . . . . . . . . . . . 21
100 5.2. Example Usage . . . . . . . . . . . . . . . . . . . . . . 21
101 5.3. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 22
102 6. Security Considerations . . . . . . . . . . . . . . . . . . . 32
103 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
104 7.1. The IETF XML Registry . . . . . . . . . . . . . . . . . . 33
105 7.2. The YANG Module Names Registry . . . . . . . . . . . . . 33
106 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 34
107 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 34
108 9.1. Normative References . . . . . . . . . . . . . . . . . . 34
109 9.2. Informative References . . . . . . . . . . . . . . . . . 35
110 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 37
111 A.1. 00 to 01 . . . . . . . . . . . . . . . . . . . . . . . . 37
112 A.2. 01 to 02 . . . . . . . . . . . . . . . . . . . . . . . . 37
113 A.3. 02 to 03 . . . . . . . . . . . . . . . . . . . . . . . . 37
114 A.4. 03 to 04 . . . . . . . . . . . . . . . . . . . . . . . . 37
115 A.5. 04 to 05 . . . . . . . . . . . . . . . . . . . . . . . . 38
116 A.6. 05 to 06 . . . . . . . . . . . . . . . . . . . . . . . . 38
117 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 38
119 1. Introduction
121 This document defines three YANG 1.1 [RFC7950] modules: the first
122 defines a grouping for a generic SSH client, the second defines a
123 grouping for a generic SSH server, and the third defines identities
124 and groupings common to both the client and the server. It is
125 intended that these groupings will be used by applications using the
126 SSH protocol [RFC4252], [RFC4253], and [RFC4254]. For instance,
127 these groupings could be used to help define the data model for an
128 OpenSSH [OPENSSH] server or a NETCONF over SSH [RFC6242] based
129 server.
131 The client and server YANG modules in this document each define one
132 grouping, which is focused on just SSH-specific configuration, and
133 specifically avoids any transport-level configuration, such as what
134 ports to listen on or connect to. This affords applications the
135 opportunity to define their own strategy for how the underlying TCP
136 connection is established. For instance, applications supporting
137 NETCONF Call Home [RFC8071] could use the "ssh-server-grouping"
138 grouping for the SSH parts it provides, while adding data nodes for
139 the TCP-level call-home configuration.
141 The modules defined in this document uses groupings defined in
142 [I-D.ietf-netconf-keystore] enabling keys to be either locally
143 defined or a reference to globally configured values.
145 The modules defined in this document optionally support [RFC6187]
146 enabling X.509v3 certificate based host keys and public keys.
148 2. Terminology
150 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
151 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
152 "OPTIONAL" in this document are to be interpreted as described in BCP
153 14 [RFC2119] [RFC8174] when, and only when, they appear in all
154 capitals, as shown here.
156 3. The SSH Client Model
158 3.1. Tree Diagram
160 This section provides two tree diagrams [RFC8340] for the "ietf-ssh-
161 client" module, the first with used groupings expanded and the second
162 with used groupings not expanded.
164 The following tree diagram has used groupings expanded:
166 module: ietf-ssh-client
168 grouping ssh-client-grouping
169 +-- client-identity
170 | +-- username? string
171 | +-- (auth-type)
172 | +--:(password)
173 | | +-- password? string
174 | +--:(public-key)
175 | | +-- public-key
176 | | +-- (local-or-keystore)
177 | | +--:(local)
178 | | | +-- algorithm ct:key-algorithm-ref
179 | | | +-- public-key binary
180 | | | +-- private-key union
181 | | +--:(keystore) {keystore-implemented}?
182 | | +-- reference ks:asymmetric-key-ref
183 | +--:(certificate)
184 | +-- certificate {sshcmn:ssh-x509-certs}?
185 | +-- (local-or-keystore)
186 | +--:(local)
187 | | +-- algorithm
188 | | | ct:key-algorithm-ref
189 | | +-- public-key binary
190 | | +-- private-key union
191 | | +-- cert
192 | | | ct:end-entity-cert-cms
193 | | +---n certificate-expiration
194 | | +-- expiration-date? yang:date-and-time
195 | +--:(keystore) {keystore-implemented}?
196 | +-- reference
197 | ks:asymmetric-key-certificate-ref
198 +-- server-auth
199 | +-- pinned-ssh-host-keys? ta:pinned-host-keys-ref
200 | +-- pinned-ca-certs? ta:pinned-certificates-ref
201 | | {sshcmn:ssh-x509-certs}?
202 | +-- pinned-server-certs? ta:pinned-certificates-ref
203 | {sshcmn:ssh-x509-certs}?
204 +-- transport-params {ssh-client-transport-params-config}?
205 +-- host-key
206 | +-- host-key-alg* identityref
207 +-- key-exchange
208 | +-- key-exchange-alg* identityref
209 +-- encryption
210 | +-- encryption-alg* identityref
211 +-- mac
212 +-- mac-alg* identityref
214 The following tree diagram does not have the groupings expanded:
216 [Note: '\' line wrapping for formatting only]
218 module: ietf-ssh-client
220 grouping ssh-client-grouping
221 +-- client-identity
222 | +-- username? string
223 | +-- (auth-type)
224 | +--:(password)
225 | | +-- password? string
226 | +--:(public-key)
227 | | +-- public-key
228 | | +---u ks:local-or-keystore-asymmetric-key-grouping
229 | +--:(certificate)
230 | +-- certificate {sshcmn:ssh-x509-certs}?
231 | +---u ks:local-or-keystore-end-entity-certificate-gr\
232 ouping
233 +-- server-auth
234 | +-- pinned-ssh-host-keys? ta:pinned-host-keys-ref
235 | +-- pinned-ca-certs? ta:pinned-certificates-ref
236 | | {sshcmn:ssh-x509-certs}?
237 | +-- pinned-server-certs? ta:pinned-certificates-ref
238 | {sshcmn:ssh-x509-certs}?
239 +-- transport-params {ssh-client-transport-params-config}?
240 +---u sshcmn:transport-params-grouping
242 3.2. Example Usage
244 This section presents two examples showing the ssh-client-grouping
245 populated with some data. These examples are effectively the same
246 except the first configures the client identity using a local key
247 while the second uses a key configured in a keystore. Both examples
248 are consistent with the examples presented in Section 3 of
249 [I-D.ietf-netconf-trust-anchors] and Section 3.2 of
250 [I-D.ietf-netconf-keystore].
252 The following example configures the client identity using a local
253 key:
255 [Note: '\' line wrapping for formatting only]
257
261
262
263 foobar
264
265 ct:rsa1024
267 base64encodedvalue==
268 base64encodedvalue==
269
270
272
273
274 explicitly-trusted-ssh-host-keys
276
278
279
280 algs:ssh-rsa
281
282
283
284 algs:diffie-hellman-group-exchange-sha256
285
286
287
288 algs:aes256-ctr
289 algs:aes192-ctr
290 algs:aes128-ctr
291 algs:aes256-cbc
292 algs:aes192-cbc
293 algs:aes128-cbc
294
295
296 algs:hmac-sha2-256
297 algs:hmac-sha2-512
298
299
301
302 The following example configures the client identity using a key from
303 the keystore:
305 [Note: '\' line wrapping for formatting only]
307
311
312
313 foobar
314
315 ex-rsa-key
316
317
319
320
321 explicitly-trusted-ssh-host-keys
323
325
326
327 algs:ssh-rsa
328
329
330
331 algs:diffie-hellman-group-exchange-sha256
332
333
334
335 algs:aes256-ctr
336 algs:aes192-ctr
337 algs:aes128-ctr
338 algs:aes256-cbc
339 algs:aes192-cbc
340 algs:aes128-cbc
341
342
343 algs:hmac-sha2-256
344 algs:hmac-sha2-512
345
346
348
350 3.3. YANG Module
352 This YANG module has normative references to [RFC6536],
353 [I-D.ietf-netconf-trust-anchors], and [I-D.ietf-netconf-keystore].
355 file "ietf-ssh-client@2018-06-04.yang"
356 module ietf-ssh-client {
357 yang-version 1.1;
359 namespace "urn:ietf:params:xml:ns:yang:ietf-ssh-client";
360 prefix "sshc";
362 import ietf-ssh-common {
363 prefix sshcmn;
364 revision-date 2018-06-04; // stable grouping definitions
365 reference
366 "RFC XXXX: YANG Groupings for SSH Clients and SSH Servers";
367 }
369 import ietf-trust-anchors {
370 prefix ta;
371 reference
372 "RFC YYYY: YANG Data Model for Global Trust Anchors";
373 }
375 import ietf-keystore {
376 prefix ks;
377 reference
378 "RFC ZZZZ:
379 YANG Data Model for a Centralized Keystore Mechanism";
380 }
382 organization
383 "IETF NETCONF (Network Configuration) Working Group";
385 contact
386 "WG Web:
387 WG List:
389 Author: Kent Watsen
390
392 Author: Gary Wu
393 ";
395 description
396 "This module defines a reusable grouping for a SSH client that
397 can be used as a basis for specific SSH client instances.
399 Copyright (c) 2018 IETF Trust and the persons identified as
400 authors of the code. All rights reserved.
402 Redistribution and use in source and binary forms, with or
403 without modification, is permitted pursuant to, and subject
404 to the license terms contained in, the Simplified BSD
405 License set forth in Section 4.c of the IETF Trust's
406 Legal Provisions Relating to IETF Documents
407 (http://trustee.ietf.org/license-info).
409 This version of this YANG module is part of RFC XXXX; see
410 the RFC itself for full legal notices.";
412 revision "2018-06-04" {
413 description
414 "Initial version";
415 reference
416 "RFC XXXX: YANG Groupings for SSH Clients and SSH Servers";
417 }
419 // features
421 feature ssh-client-transport-params-config {
422 description
423 "SSH transport layer parameters are configurable on an SSH
424 client.";
425 }
427 // groupings
429 grouping ssh-client-grouping {
430 description
431 "A reusable grouping for configuring a SSH client without
432 any consideration for how an underlying TCP session is
433 established.";
435 container client-identity {
436 description
437 "The credentials used by the client to authenticate to
438 the SSH server.";
440 leaf username {
441 type string;
442 description
443 "The username of this user. This will be the username
444 used, for instance, to log into an SSH server.";
446 }
448 choice auth-type {
449 mandatory true;
450 description
451 "The authentication type.";
452 leaf password {
453 type string;
454 description
455 "A password to be used for client authentication.";
456 }
457 container public-key {
458 uses ks:local-or-keystore-asymmetric-key-grouping;
459 description
460 "A locally-defined or referenced asymmetric key pair
461 to be used for client authentication.";
462 reference
463 "RFC ZZZZ:
464 YANG Data Model for a Centralized Keystore Mechanism";
465 }
466 container certificate {
467 if-feature sshcmn:ssh-x509-certs;
468 uses ks:local-or-keystore-end-entity-certificate-grouping;
469 description
470 "A locally-defined or referenced certificate
471 to be used for client authentication.";
472 reference
473 "RFC ZZZZ
474 YANG Data Model for a Centralized Keystore Mechanism";
475 }
476 } // end auth-type
477 } // end client-identity
479 container server-auth {
480 must 'pinned-ssh-host-keys or pinned-ca-certs or '
481 + 'pinned-server-certs';
482 description
483 "Trusted server identities.";
484 leaf pinned-ssh-host-keys {
485 type ta:pinned-host-keys-ref;
486 description
487 "A reference to a list of SSH host keys used by the
488 SSH client to authenticate SSH server host keys.
489 A server host key is authenticated if it is an exact
490 match to a configured SSH host key.";
491 reference
492 "RFC YYYY: YANG Data Model for Global Trust Anchors";
493 }
494 leaf pinned-ca-certs {
495 if-feature sshcmn:ssh-x509-certs;
496 type ta:pinned-certificates-ref;
497 description
498 "A reference to a list of certificate authority (CA)
499 certificates used by the SSH client to authenticate
500 SSH server certificates. A server certificate is
501 authenticated if it has a valid chain of trust to
502 a configured CA certificate.";
503 reference
504 "RFC YYYY: YANG Data Model for Global Trust Anchors";
505 }
507 leaf pinned-server-certs {
508 if-feature sshcmn:ssh-x509-certs;
509 type ta:pinned-certificates-ref;
510 description
511 "A reference to a list of server certificates used by
512 the SSH client to authenticate SSH server certificates.
513 A server certificate is authenticated if it is an
514 exact match to a configured server certificate.";
515 reference
516 "RFC YYYY: YANG Data Model for Global Trust Anchors";
517 }
518 } // end server-auth
520 container transport-params {
521 if-feature ssh-client-transport-params-config;
522 description
523 "Configurable parameters of the SSH transport layer.";
524 uses sshcmn:transport-params-grouping;
525 }
527 } // end ssh-client-grouping
529 }
530
532 4. The SSH Server Model
534 4.1. Tree Diagram
536 This section provides two tree diagrams [RFC8340] for the "ietf-ssh-
537 server" module, the first with used groupings expanded and the second
538 with used groupings not expanded.
540 The following tree diagram has used groupings expanded:
542 [Note: '\' line wrapping for formatting only]
544 module: ietf-ssh-server
546 grouping ssh-server-grouping
547 +-- server-identity
548 | +-- host-key* [name]
549 | +-- name? string
550 | +-- (host-key-type)
551 | +--:(public-key)
552 | | +-- public-key
553 | | +-- (local-or-keystore)
554 | | +--:(local)
555 | | | +-- algorithm ct:key-algorithm-ref
556 | | | +-- public-key binary
557 | | | +-- private-key union
558 | | +--:(keystore) {keystore-implemented}?
559 | | +-- reference ks:asymmetric-key-ref
560 | +--:(certificate)
561 | +-- certificate {sshcmn:ssh-x509-certs}?
562 | +-- (local-or-keystore)
563 | +--:(local)
564 | | +-- algorithm
565 | | | ct:key-algorithm-ref
566 | | +-- public-key binary
567 | | +-- private-key union
568 | | +-- cert
569 | | | ct:end-entity-cert-cms
570 | | +---n certificate-expiration
571 | | +-- expiration-date? yang:date-and-tim\
572 e
573 | +--:(keystore) {keystore-implemented}?
574 | +-- reference
575 | ks:asymmetric-key-certificate-ref
576 +-- client-cert-auth {sshcmn:ssh-x509-certs}?
577 | +-- pinned-ca-certs? ta:pinned-certificates-ref
578 | +-- pinned-client-certs? ta:pinned-certificates-ref
579 +-- transport-params {ssh-server-transport-params-config}?
580 +-- host-key
581 | +-- host-key-alg* identityref
582 +-- key-exchange
583 | +-- key-exchange-alg* identityref
584 +-- encryption
585 | +-- encryption-alg* identityref
586 +-- mac
587 +-- mac-alg* identityref
589 The following tree diagram does not have the used groupings expanded:
591 [Note: '\' line wrapping for formatting only]
593 module: ietf-ssh-server
595 grouping ssh-server-grouping
596 +-- server-identity
597 | +-- host-key* [name]
598 | +-- name? string
599 | +-- (host-key-type)
600 | +--:(public-key)
601 | | +-- public-key
602 | | +---u ks:local-or-keystore-asymmetric-key-groupin\
603 g
604 | +--:(certificate)
605 | +-- certificate {sshcmn:ssh-x509-certs}?
606 | +---u ks:local-or-keystore-end-entity-certificate\
607 -grouping
608 +-- client-cert-auth {sshcmn:ssh-x509-certs}?
609 | +-- pinned-ca-certs? ta:pinned-certificates-ref
610 | +-- pinned-client-certs? ta:pinned-certificates-ref
611 +-- transport-params {ssh-server-transport-params-config}?
612 +---u sshcmn:transport-params-grouping
614 4.2. Example Usage
616 This section presents two examples showing the ssh-server-grouping
617 populated with some data. These examples are effectively the same
618 except the first configures the server identity using a local key
619 while the second uses a key configured in a keystore. Both examples
620 are consistent with the examples presented in Section 3 of
621 [I-D.ietf-netconf-trust-anchors] and Section 3.2 of
622 [I-D.ietf-netconf-keystore].
624 The following example configures the server identity using a local
625 key:
627 [Note: '\' line wrapping for formatting only]
629
633
634
635
636 deployment-specific-certificate
637
638 ct:rsa1024
640 base64encodedvalue==
641 base64encodedvalue==
642
643
644
646
647
648 explicitly-trusted-client-ca-certs
650 explicitly-trusted-client-certs
652
654
655
656 algs:ssh-rsa
657
658
659
660 algs:diffie-hellman-group-exchange-sha256
661
662
663
664 algs:aes256-ctr
665 algs:aes192-ctr
666 algs:aes128-ctr
667 algs:aes256-cbc
668 algs:aes192-cbc
669 algs:aes128-cbc
670
671
672 algs:hmac-sha2-256
673 algs:hmac-sha2-512
674
675
677
679 The following example configures the server identity using a key from
680 the keystore:
682 [Note: '\' line wrapping for formatting only]
684
688
689
690
691 deployment-specific-certificate
692
693 ex-rsa-key
694
695
696
698
699
700 explicitly-trusted-client-ca-certs
702 explicitly-trusted-client-certs
704
706
707
708 algs:ssh-rsa
709
710
711
712 algs:diffie-hellman-group-exchange-sha256
713
714
715
716 algs:aes256-ctr
717 algs:aes192-ctr
718 algs:aes128-ctr
719 algs:aes256-cbc
720 algs:aes192-cbc
721 algs:aes128-cbc
722
723
724 algs:hmac-sha2-256
725 algs:hmac-sha2-512
726
727
729
731 4.3. YANG Module
733 This YANG module has normative references to
734 [I-D.ietf-netconf-trust-anchors] and [I-D.ietf-netconf-keystore] and
735 informative references to [RFC4253] and [RFC7317].
737 file "ietf-ssh-server@2018-06-04.yang"
738 module ietf-ssh-server {
739 yang-version 1.1;
741 namespace "urn:ietf:params:xml:ns:yang:ietf-ssh-server";
742 prefix "sshs";
744 import ietf-ssh-common {
745 prefix sshcmn;
746 revision-date 2018-06-04; // stable grouping definitions
747 reference
748 "RFC XXXX: YANG Groupings for SSH Clients and SSH Servers";
749 }
751 import ietf-trust-anchors {
752 prefix ta;
753 reference
754 "RFC YYYY: YANG Data Model for Global Trust Anchors";
755 }
757 import ietf-keystore {
758 prefix ks;
759 reference
760 "RFC ZZZZ:
761 YANG Data Model for a Centralized Keystore Mechanism";
762 }
764 organization
765 "IETF NETCONF (Network Configuration) Working Group";
767 contact
768 "WG Web:
769 WG List:
771 Author: Kent Watsen
772
774 Author: Gary Wu
775 ";
777 description
778 "This module defines a reusable grouping for a SSH server that
779 can be used as a basis for specific SSH server instances.
781 Copyright (c) 2018 IETF Trust and the persons identified as
782 authors of the code. All rights reserved.
784 Redistribution and use in source and binary forms, with or
785 without modification, is permitted pursuant to, and subject
786 to the license terms contained in, the Simplified BSD
787 License set forth in Section 4.c of the IETF Trust's
788 Legal Provisions Relating to IETF Documents
789 (http://trustee.ietf.org/license-info).
791 This version of this YANG module is part of RFC XXXX; see
792 the RFC itself for full legal notices.";
794 revision "2018-06-04" {
795 description
796 "Initial version";
797 reference
798 "RFC XXXX: YANG Groupings for SSH Clients and SSH Servers";
799 }
801 // features
803 feature ssh-server-transport-params-config {
804 description
805 "SSH transport layer parameters are configurable on an SSH
806 server.";
807 }
809 // groupings
811 grouping ssh-server-grouping {
812 description
813 "A reusable grouping for configuring a SSH server without
814 any consideration for how underlying TCP sessions are
815 established.";
817 container server-identity {
818 description
819 "The list of host-keys the SSH server will present when
820 establishing a SSH connection.";
821 list host-key {
822 key name;
823 min-elements 1;
824 ordered-by user;
825 description
826 "An ordered list of host keys the SSH server will use to
827 construct its ordered list of algorithms, when sending
828 its SSH_MSG_KEXINIT message, as defined in Section 7.1
829 of RFC 4253.";
830 reference
831 "RFC 4253: The Secure Shell (SSH) Transport Layer
832 Protocol";
833 leaf name {
834 type string;
835 description
836 "An arbitrary name for this host-key";
837 }
838 choice host-key-type {
839 mandatory true;
840 description
841 "The type of host key being specified";
842 container public-key {
843 uses ks:local-or-keystore-asymmetric-key-grouping;
844 description
845 "A locally-defined or referenced asymmetric key pair
846 to be used for the SSH server's host key.";
847 reference
848 "RFC ZZZZ: YANG Data Model for a Centralized
849 Keystore Mechanism";
850 }
851 container certificate {
852 if-feature sshcmn:ssh-x509-certs;
853 uses
854 ks:local-or-keystore-end-entity-certificate-grouping;
855 description
856 "A locally-defined or referenced end-entity
857 certificate to be used for the SSH server's
858 host key.";
859 reference
860 "RFC ZZZZ: YANG Data Model for a Centralized
861 Keystore Mechanism";
862 }
863 }
864 }
865 }
867 container client-cert-auth {
868 if-feature sshcmn:ssh-x509-certs;
869 description
870 "A reference to a list of pinned certificate authority (CA)
871 certificates and a reference to a list of pinned client
872 certificates.
874 Note: password and public-key based client authentication
875 is not configured in this YANG module as they are
876 expected to be configured by the ietf-system module
877 defined in RFC 7317 ";
878 reference
879 "RFC 7317: A YANG Data Model for System Management";
880 leaf pinned-ca-certs {
881 type ta:pinned-certificates-ref;
882 description
883 "A reference to a list of certificate authority (CA)
884 certificates used by the SSH server to authenticate
885 SSH client certificates. A client certificate is
886 authenticated if it has a valid chain of trust to
887 a configured pinned CA certificate.";
888 reference
889 "RFC YYYY: YANG Data Model for Global Trust Anchors";
890 }
891 leaf pinned-client-certs {
892 type ta:pinned-certificates-ref;
893 description
894 "A reference to a list of client certificates used by
895 the SSH server to authenticate SSH client certificates.
896 A clients certificate is authenticated if it is an
897 exact match to a configured pinned client certificate.";
898 reference
899 "RFC YYYY: YANG Data Model for Global Trust Anchors";
900 }
901 }
903 container transport-params {
904 if-feature ssh-server-transport-params-config;
905 description
906 "Configurable parameters of the SSH transport layer.";
907 uses sshcmn:transport-params-grouping;
908 }
910 } // end ssh-server-grouping
912 }
913
915 5. The SSH Common Model
917 The SSH common model presented in this section contains identities
918 and groupings common to both SSH clients and SSH servers. The
919 transport-params-grouping can be used to configure the list of SSH
920 transport algorithms permitted by the SSH client or SSH server. The
921 lists of algorithms are ordered such that, if multiple algorithms are
922 permitted by the client, the algorithm that appears first in its list
923 that is also permitted by the server is used for the SSH transport
924 layer connection. The ability to restrict the the algorithms allowed
925 is provided in this grouping for SSH clients and SSH servers that are
926 capable of doing so and may serve to make SSH clients and SSH servers
927 compliant with security policies.
929 Features are defined for algorithms that are OPTIONAL or are not
930 widely supported by popular implementations. Note that the list of
931 algorithms is not exhaustive. As well, some algorithms that are
932 REQUIRED by [RFC4253] are missing, notably "ssh-dss" and "diffie-
933 hellman-group1-sha1" due to their weak security and there being
934 alternatives that are widely supported.
936 5.1. Tree Diagram
938 The following tree diagram [RFC8340] provides an overview of the data
939 model for the "ietf-ssh-common" module.
941 module: ietf-ssh-common
943 grouping transport-params-grouping
944 +-- host-key
945 | +-- host-key-alg* identityref
946 +-- key-exchange
947 | +-- key-exchange-alg* identityref
948 +-- encryption
949 | +-- encryption-alg* identityref
950 +-- mac
951 +-- mac-alg* identityref
953 5.2. Example Usage
955 This following example illustrates how the transport-params-grouping
956 appears when populated with some data.
958
961
962 algs:x509v3-rsa2048-sha256
963 algs:ssh-rsa
964
965
966
967 algs:diffie-hellman-group-exchange-sha256
968
969
970
971 algs:aes256-ctr
972 algs:aes192-ctr
973 algs:aes128-ctr
974 algs:aes256-cbc
975 algs:aes192-cbc
976 algs:aes128-cbc
977
978
979 algs:hmac-sha2-256
980 algs:hmac-sha2-512
981
982
984 5.3. YANG Module
986 This YANG module has normative references to [RFC4253], [RFC4344],
987 [RFC4419], [RFC5656], [RFC6187], and [RFC6668].
989 file "ietf-ssh-common@2018-06-04.yang"
990 module ietf-ssh-common {
991 yang-version 1.1;
993 namespace "urn:ietf:params:xml:ns:yang:ietf-ssh-common";
994 prefix "sshcmn";
996 organization
997 "IETF NETCONF (Network Configuration) Working Group";
999 contact
1000 "WG Web:
1001 WG List:
1003 Author: Kent Watsen
1004
1006 Author: Gary Wu
1007 ";
1009 description
1010 "This module defines a common features, identities, and
1011 groupings for Secure Shell (SSH).
1013 Copyright (c) 2018 IETF Trust and the persons identified as
1014 authors of the code. All rights reserved.
1016 Redistribution and use in source and binary forms, with or
1017 without modification, is permitted pursuant to, and subject
1018 to the license terms contained in, the Simplified BSD
1019 License set forth in Section 4.c of the IETF Trust's
1020 Legal Provisions Relating to IETF Documents
1021 (http://trustee.ietf.org/license-info).
1023 This version of this YANG module is part of RFC XXXX; see
1024 the RFC itself for full legal notices.";
1026 revision "2018-06-04" {
1027 description
1028 "Initial version";
1029 reference
1030 "RFC XXXX: YANG Groupings for SSH Clients and SSH Servers";
1031 }
1033 // features
1035 feature ssh-ecc {
1036 description
1037 "Elliptic Curve Cryptography is supported for SSH.";
1038 reference
1039 "RFC 5656: Elliptic Curve Algorithm Integration in the
1040 Secure Shell Transport Layer";
1041 }
1043 feature ssh-x509-certs {
1044 description
1045 "X.509v3 certificates are supported for SSH per RFC 6187.";
1046 reference
1047 "RFC 6187: X.509v3 Certificates for Secure Shell
1048 Authentication";
1049 }
1051 feature ssh-dh-group-exchange {
1052 description
1053 "Diffie-Hellman Group Exchange is supported for SSH.";
1055 reference
1056 "RFC 4419: Diffie-Hellman Group Exchange for the
1057 Secure Shell (SSH) Transport Layer Protocol";
1058 }
1060 feature ssh-ctr {
1061 description
1062 "SDCTR encryption mode is supported for SSH.";
1063 reference
1064 "RFC 4344: The Secure Shell (SSH) Transport Layer
1065 Encryption Modes";
1066 }
1068 feature ssh-sha2 {
1069 description
1070 "The SHA2 family of cryptographic hash functions is
1071 supported for SSH.";
1072 reference
1073 "FIPS PUB 180-4: Secure Hash Standard (SHS)";
1074 }
1076 // identities
1078 identity public-key-alg-base {
1079 description
1080 "Base identity used to identify public key algorithms.";
1081 }
1083 identity ssh-dss {
1084 base public-key-alg-base;
1085 description
1086 "Digital Signature Algorithm using SHA-1 as the
1087 hashing algorithm.";
1088 reference
1089 "RFC 4253:
1090 The Secure Shell (SSH) Transport Layer Protocol";
1091 }
1093 identity ssh-rsa {
1094 base public-key-alg-base;
1095 description
1096 "RSASSA-PKCS1-v1_5 signature scheme using SHA-1 as the
1097 hashing algorithm.";
1098 reference
1099 "RFC 4253:
1100 The Secure Shell (SSH) Transport Layer Protocol";
1101 }
1102 identity ecdsa-sha2-nistp256 {
1103 base public-key-alg-base;
1104 if-feature "ssh-ecc and ssh-sha2";
1105 description
1106 "Elliptic Curve Digital Signature Algorithm (ECDSA) using the
1107 nistp256 curve and the SHA2 family of hashing algorithms.";
1108 reference
1109 "RFC 5656: Elliptic Curve Algorithm Integration in the
1110 Secure Shell Transport Layer";
1111 }
1113 identity ecdsa-sha2-nistp384 {
1114 base public-key-alg-base;
1115 if-feature "ssh-ecc and ssh-sha2";
1116 description
1117 "Elliptic Curve Digital Signature Algorithm (ECDSA) using the
1118 nistp384 curve and the SHA2 family of hashing algorithms.";
1119 reference
1120 "RFC 5656: Elliptic Curve Algorithm Integration in the
1121 Secure Shell Transport Layer";
1122 }
1124 identity ecdsa-sha2-nistp521 {
1125 base public-key-alg-base;
1126 if-feature "ssh-ecc and ssh-sha2";
1127 description
1128 "Elliptic Curve Digital Signature Algorithm (ECDSA) using the
1129 nistp521 curve and the SHA2 family of hashing algorithms.";
1130 reference
1131 "RFC 5656: Elliptic Curve Algorithm Integration in the
1132 Secure Shell Transport Layer";
1133 }
1135 identity x509v3-ssh-rsa {
1136 base public-key-alg-base;
1137 if-feature ssh-x509-certs;
1138 description
1139 "RSASSA-PKCS1-v1_5 signature scheme using a public key stored
1140 in an X.509v3 certificate and using SHA-1 as the hashing
1141 algorithm.";
1142 reference
1143 "RFC 6187: X.509v3 Certificates for Secure Shell
1144 Authentication";
1145 }
1147 identity x509v3-rsa2048-sha256 {
1148 base public-key-alg-base;
1149 if-feature "ssh-x509-certs and ssh-sha2";
1150 description
1151 "RSASSA-PKCS1-v1_5 signature scheme using a public key stored
1152 in an X.509v3 certificate and using SHA-256 as the hashing
1153 algorithm. RSA keys conveyed using this format MUST have a
1154 modulus of at least 2048 bits.";
1155 reference
1156 "RFC 6187: X.509v3 Certificates for Secure Shell
1157 Authentication";
1158 }
1160 identity x509v3-ecdsa-sha2-nistp256 {
1161 base public-key-alg-base;
1162 if-feature "ssh-ecc and ssh-x509-certs and ssh-sha2";
1163 description
1164 "Elliptic Curve Digital Signature Algorithm (ECDSA)
1165 using the nistp256 curve with a public key stored in
1166 an X.509v3 certificate and using the SHA2 family of
1167 hashing algorithms.";
1168 reference
1169 "RFC 6187: X.509v3 Certificates for Secure Shell
1170 Authentication";
1171 }
1173 identity x509v3-ecdsa-sha2-nistp384 {
1174 base public-key-alg-base;
1175 if-feature "ssh-ecc and ssh-x509-certs and ssh-sha2";
1176 description
1177 "Elliptic Curve Digital Signature Algorithm (ECDSA)
1178 using the nistp384 curve with a public key stored in
1179 an X.509v3 certificate and using the SHA2 family of
1180 hashing algorithms.";
1181 reference
1182 "RFC 6187: X.509v3 Certificates for Secure Shell
1183 Authentication";
1184 }
1186 identity x509v3-ecdsa-sha2-nistp521 {
1187 base public-key-alg-base;
1188 if-feature "ssh-ecc and ssh-x509-certs and ssh-sha2";
1189 description
1190 "Elliptic Curve Digital Signature Algorithm (ECDSA)
1191 using the nistp521 curve with a public key stored in
1192 an X.509v3 certificate and using the SHA2 family of
1193 hashing algorithms.";
1194 reference
1195 "RFC 6187: X.509v3 Certificates for Secure Shell
1196 Authentication";
1197 }
1198 identity key-exchange-alg-base {
1199 description
1200 "Base identity used to identify key exchange algorithms.";
1201 }
1203 identity diffie-hellman-group14-sha1 {
1204 base key-exchange-alg-base;
1205 description
1206 "Diffie-Hellman key exchange with SHA-1 as HASH and
1207 Oakley Group 14 (2048-bit MODP Group).";
1208 reference
1209 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1210 }
1212 identity diffie-hellman-group-exchange-sha1 {
1213 base key-exchange-alg-base;
1214 if-feature ssh-dh-group-exchange;
1215 description
1216 "Diffie-Hellman Group and Key Exchange with SHA-1 as HASH.";
1217 reference
1218 "RFC 4419: Diffie-Hellman Group Exchange for the
1219 Secure Shell (SSH) Transport Layer Protocol";
1220 }
1222 identity diffie-hellman-group-exchange-sha256 {
1223 base key-exchange-alg-base;
1224 if-feature "ssh-dh-group-exchange and ssh-sha2";
1225 description
1226 "Diffie-Hellman Group and Key Exchange with SHA-256 as HASH.";
1227 reference
1228 "RFC 4419: Diffie-Hellman Group Exchange for the
1229 Secure Shell (SSH) Transport Layer Protocol";
1230 }
1232 identity ecdh-sha2-nistp256 {
1233 base key-exchange-alg-base;
1234 if-feature "ssh-ecc and ssh-sha2";
1235 description
1236 "Elliptic Curve Diffie-Hellman (ECDH) key exchange using the
1237 nistp256 curve and the SHA2 family of hashing algorithms.";
1238 reference
1239 "RFC 5656: Elliptic Curve Algorithm Integration in the
1240 Secure Shell Transport Layer";
1241 }
1243 identity ecdh-sha2-nistp384 {
1244 base key-exchange-alg-base;
1245 if-feature "ssh-ecc and ssh-sha2";
1246 description
1247 "Elliptic Curve Diffie-Hellman (ECDH) key exchange using the
1248 nistp384 curve and the SHA2 family of hashing algorithms.";
1249 reference
1250 "RFC 5656: Elliptic Curve Algorithm Integration in the
1251 Secure Shell Transport Layer";
1252 }
1254 identity ecdh-sha2-nistp521 {
1255 base key-exchange-alg-base;
1256 if-feature "ssh-ecc and ssh-sha2";
1257 description
1258 "Elliptic Curve Diffie-Hellman (ECDH) key exchange using the
1259 nistp521 curve and the SHA2 family of hashing algorithms.";
1260 reference
1261 "RFC 5656: Elliptic Curve Algorithm Integration in the
1262 Secure Shell Transport Layer";
1263 }
1265 identity encryption-alg-base {
1266 description
1267 "Base identity used to identify encryption algorithms.";
1268 }
1270 identity triple-des-cbc {
1271 base encryption-alg-base;
1272 description
1273 "Three-key 3DES in CBC mode.";
1274 reference
1275 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1276 }
1278 identity aes128-cbc {
1279 base encryption-alg-base;
1280 description
1281 "AES in CBC mode, with a 128-bit key.";
1282 reference
1283 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1284 }
1286 identity aes192-cbc {
1287 base encryption-alg-base;
1288 description
1289 "AES in CBC mode, with a 192-bit key.";
1290 reference
1291 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1292 }
1293 identity aes256-cbc {
1294 base encryption-alg-base;
1295 description
1296 "AES in CBC mode, with a 256-bit key.";
1297 reference
1298 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1299 }
1301 identity aes128-ctr {
1302 base encryption-alg-base;
1303 if-feature ssh-ctr;
1304 description
1305 "AES in SDCTR mode, with 128-bit key.";
1306 reference
1307 "RFC 4344: The Secure Shell (SSH) Transport Layer Encryption
1308 Modes";
1309 }
1311 identity aes192-ctr {
1312 base encryption-alg-base;
1313 if-feature ssh-ctr;
1314 description
1315 "AES in SDCTR mode, with 192-bit key.";
1316 reference
1317 "RFC 4344: The Secure Shell (SSH) Transport Layer Encryption
1318 Modes";
1319 }
1321 identity aes256-ctr {
1322 base encryption-alg-base;
1323 if-feature ssh-ctr;
1324 description
1325 "AES in SDCTR mode, with 256-bit key.";
1326 reference
1327 "RFC 4344: The Secure Shell (SSH) Transport Layer Encryption
1328 Modes";
1329 }
1331 identity mac-alg-base {
1332 description
1333 "Base identity used to identify message authentication
1334 code (MAC) algorithms.";
1335 }
1337 identity hmac-sha1 {
1338 base mac-alg-base;
1339 description
1340 "HMAC-SHA1";
1342 reference
1343 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1344 }
1346 identity hmac-sha2-256 {
1347 base mac-alg-base;
1348 if-feature "ssh-sha2";
1349 description
1350 "HMAC-SHA2-256";
1351 reference
1352 "RFC 6668: SHA-2 Data Integrity Verification for the
1353 Secure Shell (SSH) Transport Layer Protocol";
1354 }
1356 identity hmac-sha2-512 {
1357 base mac-alg-base;
1358 if-feature "ssh-sha2";
1359 description
1360 "HMAC-SHA2-512";
1361 reference
1362 "RFC 6668: SHA-2 Data Integrity Verification for the
1363 Secure Shell (SSH) Transport Layer Protocol";
1364 }
1366 // groupings
1368 grouping transport-params-grouping {
1369 description
1370 "A reusable grouping for SSH transport parameters.";
1371 reference
1372 "RFC 4253: The Secure Shell (SSH) Transport Layer Protocol";
1373 container host-key {
1374 description
1375 "Parameters regarding host key.";
1376 leaf-list host-key-alg {
1377 type identityref {
1378 base public-key-alg-base;
1379 }
1380 ordered-by user;
1381 description
1382 "Acceptable host key algorithms in order of descending
1383 preference.
1385 If this leaf-list is not configured (has zero elements)
1386 the acceptable host key algorithms are implementation-
1387 defined.";
1388 }
1389 }
1390 container key-exchange {
1391 description
1392 "Parameters regarding key exchange.";
1393 leaf-list key-exchange-alg {
1394 type identityref {
1395 base key-exchange-alg-base;
1396 }
1397 ordered-by user;
1398 description
1399 "Acceptable key exchange algorithms in order of descending
1400 preference.
1402 If this leaf-list is not configured (has zero elements)
1403 the acceptable key exchange algorithms are implementation
1404 defined.";
1405 }
1406 }
1407 container encryption {
1408 description
1409 "Parameters regarding encryption.";
1410 leaf-list encryption-alg {
1411 type identityref {
1412 base encryption-alg-base;
1413 }
1414 ordered-by user;
1415 description
1416 "Acceptable encryption algorithms in order of descending
1417 preference.
1419 If this leaf-list is not configured (has zero elements)
1420 the acceptable encryption algorithms are implementation
1421 defined.";
1422 }
1423 }
1424 container mac {
1425 description
1426 "Parameters regarding message authentication code (MAC).";
1427 leaf-list mac-alg {
1428 type identityref {
1429 base mac-alg-base;
1430 }
1431 ordered-by user;
1432 description
1433 "Acceptable MAC algorithms in order of descending
1434 preference.
1436 If this leaf-list is not configured (has zero elements)
1437 the acceptable MAC algorithms are implementation-
1438 defined.";
1439 }
1440 }
1442 } // transport-params-grouping
1444 }
1445
1447 6. Security Considerations
1449 The YANG modules defined in this document are designed to be accessed
1450 via YANG based management protocols, such as NETCONF [RFC6241] and
1451 RESTCONF [RFC8040]. Both of these protocols have mandatory-to-
1452 implement secure transport layers (e.g., SSH, TLS) with mutual
1453 authentication.
1455 The NETCONF access control model (NACM) [RFC6536] provides the means
1456 to restrict access for particular users to a pre-configured subset of
1457 all available protocol operations and content.
1459 Since the modules defined in this document define only groupings,
1460 these considerations are primarily for the designers of other modules
1461 that use these groupings.
1463 There are a number of data nodes defined in the YANG modules that are
1464 writable/creatable/deletable (i.e., config true, which is the
1465 default). These data nodes may be considered sensitive or vulnerable
1466 in some network environments. Write operations (e.g., edit-config)
1467 to these data nodes without proper protection can have a negative
1468 effect on network operations. These are the subtrees and data nodes
1469 and their sensitivity/vulnerability:
1471 /: The entire data tree defined by all the modules defined in this
1472 draft are sensitive to write operations. For instance, the
1473 addition or removal of references to keys, certificates,
1474 trusted anchors, etc., can dramatically alter the implemented
1475 security policy. However, no NACM annotations are applied as
1476 the data SHOULD be editable by users other than a designated
1477 'recovery session'.
1479 Some of the readable data nodes in the YANG modules may be considered
1480 sensitive or vulnerable in some network environments. It is thus
1481 important to control read access (e.g., via get, get-config, or
1482 notification) to these data nodes. These are the subtrees and data
1483 nodes and their sensitivity/vulnerability:
1485 /client-auth/password: This node in the 'ietf-ssh-client' module
1486 is additionally sensitive to read operations such that, in
1487 normal use cases, it should never be returned to a client. The
1488 only time this node should be returned is to support backup/
1489 restore type workflows. However, no NACM annotations are
1490 applied as the data SHOULD be writable by users other than a
1491 designated 'recovery session'.
1493 Some of the RPC operations in this YANG module may be considered
1494 sensitive or vulnerable in some network environments. It is thus
1495 important to control access to these operations. These are the
1496 operations and their sensitivity/vulnerability:
1498 NONE
1500 7. IANA Considerations
1502 7.1. The IETF XML Registry
1504 This document registers three URIs in the IETF XML registry
1505 [RFC3688]. Following the format in [RFC3688], the following
1506 registrations are requested:
1508 URI: urn:ietf:params:xml:ns:yang:ietf-ssh-client
1509 Registrant Contact: The NETCONF WG of the IETF.
1510 XML: N/A, the requested URI is an XML namespace.
1512 URI: urn:ietf:params:xml:ns:yang:ietf-ssh-server
1513 Registrant Contact: The NETCONF WG of the IETF.
1514 XML: N/A, the requested URI is an XML namespace.
1516 URI: urn:ietf:params:xml:ns:yang:ietf-ssh-common
1517 Registrant Contact: The NETCONF WG of the IETF.
1518 XML: N/A, the requested URI is an XML namespace.
1520 7.2. The YANG Module Names Registry
1522 This document registers three YANG modules in the YANG Module Names
1523 registry [RFC7950]. Following the format in [RFC7950], the the
1524 following registrations are requested:
1526 name: ietf-ssh-client
1527 namespace: urn:ietf:params:xml:ns:yang:ietf-ssh-client
1528 prefix: sshc
1529 reference: RFC XXXX
1531 name: ietf-ssh-server
1532 namespace: urn:ietf:params:xml:ns:yang:ietf-ssh-server
1533 prefix: sshs
1534 reference: RFC XXXX
1536 name: ietf-ssh-common
1537 namespace: urn:ietf:params:xml:ns:yang:ietf-ssh-common
1538 prefix: sshcmn
1539 reference: RFC XXXX
1541 8. Acknowledgements
1543 The authors would like to thank for following for lively discussions
1544 on list and in the halls (ordered by last name): Andy Bierman, Martin
1545 Bjorklund, Benoit Claise, Mehmet Ersue, Balazs Kovacs, David
1546 Lamparter, Alan Luchuk, Ladislav Lhotka, Radek Krejci, Tom Petch,
1547 Juergen Schoenwaelder, Phil Shafer, Sean Turner, Michal Vasko, and
1548 Bert Wijnen.
1550 9. References
1552 9.1. Normative References
1554 [I-D.ietf-netconf-keystore]
1555 Watsen, K., "YANG Data Model for a "Keystore" Mechanism",
1556 draft-ietf-netconf-keystore-04 (work in progress), October
1557 2017.
1559 [I-D.ietf-netconf-trust-anchors]
1560 Watsen, K., "YANG Data Model for Global Trust Anchors",
1561 draft-ietf-netconf-trust-anchors-00 (work in progress),
1562 June 2018.
1564 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
1565 Requirement Levels", BCP 14, RFC 2119,
1566 DOI 10.17487/RFC2119, March 1997,
1567 .
1569 [RFC4344] Bellare, M., Kohno, T., and C. Namprempre, "The Secure
1570 Shell (SSH) Transport Layer Encryption Modes", RFC 4344,
1571 DOI 10.17487/RFC4344, January 2006,
1572 .
1574 [RFC4419] Friedl, M., Provos, N., and W. Simpson, "Diffie-Hellman
1575 Group Exchange for the Secure Shell (SSH) Transport Layer
1576 Protocol", RFC 4419, DOI 10.17487/RFC4419, March 2006,
1577 .
1579 [RFC5656] Stebila, D. and J. Green, "Elliptic Curve Algorithm
1580 Integration in the Secure Shell Transport Layer",
1581 RFC 5656, DOI 10.17487/RFC5656, December 2009,
1582 .
1584 [RFC6187] Igoe, K. and D. Stebila, "X.509v3 Certificates for Secure
1585 Shell Authentication", RFC 6187, DOI 10.17487/RFC6187,
1586 March 2011, .
1588 [RFC6536] Bierman, A. and M. Bjorklund, "Network Configuration
1589 Protocol (NETCONF) Access Control Model", RFC 6536,
1590 DOI 10.17487/RFC6536, March 2012,
1591 .
1593 [RFC6668] Bider, D. and M. Baushke, "SHA-2 Data Integrity
1594 Verification for the Secure Shell (SSH) Transport Layer
1595 Protocol", RFC 6668, DOI 10.17487/RFC6668, July 2012,
1596 .
1598 [RFC7950] Bjorklund, M., Ed., "The YANG 1.1 Data Modeling Language",
1599 RFC 7950, DOI 10.17487/RFC7950, August 2016,
1600 .
1602 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
1603 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
1604 May 2017, .
1606 9.2. Informative References
1608 [OPENSSH] "OpenSSH", 2016, .
1610 [RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
1611 DOI 10.17487/RFC3688, January 2004,
1612 .
1614 [RFC4252] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
1615 Authentication Protocol", RFC 4252, DOI 10.17487/RFC4252,
1616 January 2006, .
1618 [RFC4253] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
1619 Transport Layer Protocol", RFC 4253, DOI 10.17487/RFC4253,
1620 January 2006, .
1622 [RFC4254] Ylonen, T. and C. Lonvick, Ed., "The Secure Shell (SSH)
1623 Connection Protocol", RFC 4254, DOI 10.17487/RFC4254,
1624 January 2006, .
1626 [RFC6241] Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed.,
1627 and A. Bierman, Ed., "Network Configuration Protocol
1628 (NETCONF)", RFC 6241, DOI 10.17487/RFC6241, June 2011,
1629 .
1631 [RFC6242] Wasserman, M., "Using the NETCONF Protocol over Secure
1632 Shell (SSH)", RFC 6242, DOI 10.17487/RFC6242, June 2011,
1633 .
1635 [RFC7317] Bierman, A. and M. Bjorklund, "A YANG Data Model for
1636 System Management", RFC 7317, DOI 10.17487/RFC7317, August
1637 2014, .
1639 [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
1640 Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
1641 .
1643 [RFC8071] Watsen, K., "NETCONF Call Home and RESTCONF Call Home",
1644 RFC 8071, DOI 10.17487/RFC8071, February 2017,
1645 .
1647 [RFC8340] Bjorklund, M. and L. Berger, Ed., "YANG Tree Diagrams",
1648 BCP 215, RFC 8340, DOI 10.17487/RFC8340, March 2018,
1649 .
1651 Appendix A. Change Log
1653 A.1. 00 to 01
1655 o Noted that '0.0.0.0' and '::' might have special meanings.
1657 o Renamed "keychain" to "keystore".
1659 A.2. 01 to 02
1661 o Removed the groupings 'listening-ssh-client-grouping' and
1662 'listening-ssh-server-grouping'. Now modules only contain the
1663 transport-independent groupings.
1665 o Simplified the "client-auth" part in the ietf-ssh-client module.
1666 It now inlines what it used to point to keystore for.
1668 o Added cipher suites for various algorithms into new 'ietf-ssh-
1669 common' module.
1671 A.3. 02 to 03
1673 o Removed 'RESTRICTED' enum from 'password' leaf type.
1675 o Added a 'must' statement to container 'server-auth' asserting that
1676 at least one of the various auth mechanisms must be specified.
1678 o Fixed description statement for leaf 'trusted-ca-certs'.
1680 A.4. 03 to 04
1682 o Change title to "YANG Groupings for SSH Clients and SSH Servers"
1684 o Added reference to RFC 6668
1686 o Added RFC 8174 to Requirements Language Section.
1688 o Enhanced description statement for ietf-ssh-server's "trusted-ca-
1689 certs" leaf.
1691 o Added mandatory true to ietf-ssh-client's "client-auth" 'choice'
1692 statement.
1694 o Changed the YANG prefix for module ietf-ssh-common from 'sshcom'
1695 to 'sshcmn'.
1697 o Removed the compression algorithms as they are not commonly
1698 configurable in vendors' implementations.
1700 o Updating descriptions in transport-params-grouping and the
1701 servers's usage of it.
1703 o Now tree diagrams reference ietf-netmod-yang-tree-diagrams
1705 o Updated YANG to use typedefs around leafrefs to common keystore
1706 paths
1708 o Now inlines key and certificates (no longer a leafref to keystore)
1710 A.5. 04 to 05
1712 o Merged changes from co-author.
1714 A.6. 05 to 06
1716 o Updated to use trust anchors from trust-anchors draft (was
1717 keystore draft)
1719 o Now uses new keystore grouping enabling asymmetric key to be
1720 either locally defined or a reference to the keystore.
1722 Authors' Addresses
1724 Kent Watsen
1725 Juniper Networks
1727 EMail: kwatsen@juniper.net
1729 Gary Wu
1730 Cisco Systems
1732 EMail: garywu@cisco.com