-
Notifications
You must be signed in to change notification settings - Fork 4
Expand file tree
/
Copy pathdraft-reddy-dprive-bootstrap-dns-server-01.html
More file actions
910 lines (851 loc) · 45 KB
/
draft-reddy-dprive-bootstrap-dns-server-01.html
File metadata and controls
910 lines (851 loc) · 45 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html lang="en" xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
<head profile="http://www.w3.org/2006/03/hcard http://dublincore.org/documents/2008/08/04/dc-html/">
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii" />
<title>A Bootstrapping Procedure to Discover and Authenticate DNS-over-(D)TLS and DNS-over-HTTPS Servers</title>
<style type="text/css" title="Xml2Rfc (sans serif)">
/*<![CDATA[*/
a {
text-decoration: none;
}
/* info code from SantaKlauss at http://www.madaboutstyle.com/tooltip2.html */
a.info {
/* This is the key. */
position: relative;
z-index: 24;
text-decoration: none;
}
a.info:hover {
z-index: 25;
color: #FFF; background-color: #900;
}
a.info span { display: none; }
a.info:hover span.info {
/* The span will display just on :hover state. */
display: block;
position: absolute;
font-size: smaller;
top: 2em; left: -5em; width: 15em;
padding: 2px; border: 1px solid #333;
color: #900; background-color: #EEE;
text-align: left;
}
a.smpl {
color: black;
}
a:hover {
text-decoration: underline;
}
a:active {
text-decoration: underline;
}
address {
margin-top: 1em;
margin-left: 2em;
font-style: normal;
}
body {
color: black;
font-family: verdana, helvetica, arial, sans-serif;
font-size: 10pt;
max-width: 55em;
}
cite {
font-style: normal;
}
dd {
margin-right: 2em;
}
dl {
margin-left: 2em;
}
ul.empty {
list-style-type: none;
}
ul.empty li {
margin-top: .5em;
}
dl p {
margin-left: 0em;
}
dt {
margin-top: .5em;
}
h1 {
font-size: 14pt;
line-height: 21pt;
page-break-after: avoid;
}
h1.np {
page-break-before: always;
}
h1 a {
color: #333333;
}
h2 {
font-size: 12pt;
line-height: 15pt;
page-break-after: avoid;
}
h3, h4, h5, h6 {
font-size: 10pt;
page-break-after: avoid;
}
h2 a, h3 a, h4 a, h5 a, h6 a {
color: black;
}
img {
margin-left: 3em;
}
li {
margin-left: 2em;
margin-right: 2em;
}
ol {
margin-left: 2em;
margin-right: 2em;
}
ol p {
margin-left: 0em;
}
p {
margin-left: 2em;
margin-right: 2em;
}
pre {
margin-left: 3em;
background-color: lightyellow;
padding: .25em;
}
pre.text2 {
border-style: dotted;
border-width: 1px;
background-color: #f0f0f0;
width: 69em;
}
pre.inline {
background-color: white;
padding: 0em;
}
pre.text {
border-style: dotted;
border-width: 1px;
background-color: #f8f8f8;
width: 69em;
}
pre.drawing {
border-style: solid;
border-width: 1px;
background-color: #f8f8f8;
padding: 2em;
}
table {
margin-left: 2em;
}
table.tt {
vertical-align: top;
}
table.full {
border-style: outset;
border-width: 1px;
}
table.headers {
border-style: outset;
border-width: 1px;
}
table.tt td {
vertical-align: top;
}
table.full td {
border-style: inset;
border-width: 1px;
}
table.tt th {
vertical-align: top;
}
table.full th {
border-style: inset;
border-width: 1px;
}
table.headers th {
border-style: none none inset none;
border-width: 1px;
}
table.left {
margin-right: auto;
}
table.right {
margin-left: auto;
}
table.center {
margin-left: auto;
margin-right: auto;
}
caption {
caption-side: bottom;
font-weight: bold;
font-size: 9pt;
margin-top: .5em;
}
table.header {
border-spacing: 1px;
width: 95%;
font-size: 10pt;
color: white;
}
td.top {
vertical-align: top;
}
td.topnowrap {
vertical-align: top;
white-space: nowrap;
}
table.header td {
background-color: gray;
width: 50%;
}
table.header a {
color: white;
}
td.reference {
vertical-align: top;
white-space: nowrap;
padding-right: 1em;
}
thead {
display:table-header-group;
}
ul.toc, ul.toc ul {
list-style: none;
margin-left: 1.5em;
margin-right: 0em;
padding-left: 0em;
}
ul.toc li {
line-height: 150%;
font-weight: bold;
font-size: 10pt;
margin-left: 0em;
margin-right: 0em;
}
ul.toc li li {
line-height: normal;
font-weight: normal;
font-size: 9pt;
margin-left: 0em;
margin-right: 0em;
}
li.excluded {
font-size: 0pt;
}
ul p {
margin-left: 0em;
}
.comment {
background-color: yellow;
}
.center {
text-align: center;
}
.error {
color: red;
font-style: italic;
font-weight: bold;
}
.figure {
font-weight: bold;
text-align: center;
font-size: 9pt;
}
.filename {
color: #333333;
font-weight: bold;
font-size: 12pt;
line-height: 21pt;
text-align: center;
}
.fn {
font-weight: bold;
}
.hidden {
display: none;
}
.left {
text-align: left;
}
.right {
text-align: right;
}
.title {
color: #990000;
font-size: 18pt;
line-height: 18pt;
font-weight: bold;
text-align: center;
margin-top: 36pt;
}
.vcardline {
display: block;
}
.warning {
font-size: 14pt;
background-color: yellow;
}
@media print {
.noprint {
display: none;
}
a {
color: black;
text-decoration: none;
}
table.header {
width: 90%;
}
td.header {
width: 50%;
color: black;
background-color: white;
vertical-align: top;
font-size: 12pt;
}
ul.toc a::after {
content: leader('.') target-counter(attr(href), page);
}
ul.ind li li a {
content: target-counter(attr(href), page);
}
.print2col {
column-count: 2;
-moz-column-count: 2;
column-fill: auto;
}
}
@page {
@top-left {
content: "Internet-Draft";
}
@top-right {
content: "December 2010";
}
@top-center {
content: "Abbreviated Title";
}
@bottom-left {
content: "Doe";
}
@bottom-center {
content: "Expires June 2011";
}
@bottom-right {
content: "[Page " counter(page) "]";
}
}
@page:first {
@top-left {
content: normal;
}
@top-right {
content: normal;
}
@top-center {
content: normal;
}
}
/*]]>*/
</style>
<link href="#rfc.toc" rel="Contents">
<link href="#rfc.section.1" rel="Chapter" title="1 Introduction">
<link href="#rfc.section.2" rel="Chapter" title="2 Terminology">
<link href="#rfc.section.3" rel="Chapter" title="3 Bootstrapping Endpoint Devices">
<link href="#rfc.section.4" rel="Chapter" title="4 Bootstrapping IoT Devices and CPE">
<link href="#rfc.section.5" rel="Chapter" title="5 Discovery Procedure">
<link href="#rfc.section.5.1" rel="Chapter" title="5.1 Resolution">
<link href="#rfc.section.6" rel="Chapter" title="6 Connection handshake and service invocation">
<link href="#rfc.section.7" rel="Chapter" title="7 Security Considerations">
<link href="#rfc.section.8" rel="Chapter" title="8 IANA Considerations">
<link href="#rfc.section.8.1" rel="Chapter" title="8.1 Application Service & Application Protocol Tags">
<link href="#rfc.section.8.1.1" rel="Chapter" title="8.1.1 DNS Application Service Tag Registration">
<link href="#rfc.section.8.1.2" rel="Chapter" title="8.1.2 dns.tls Application Protocol Tag Registration">
<link href="#rfc.section.8.1.3" rel="Chapter" title="8.1.3 dns.dtls Application Protocol Tag Registration">
<link href="#rfc.section.8.1.4" rel="Chapter" title="8.1.4 dns.https Application Protocol Tag Registration">
<link href="#rfc.section.9" rel="Chapter" title="9 Acknowledgments">
<link href="#rfc.references" rel="Chapter" title="10 References">
<link href="#rfc.references.1" rel="Chapter" title="10.1 Normative References">
<link href="#rfc.references.2" rel="Chapter" title="10.2 Informative References">
<link href="#rfc.authors" rel="Chapter">
<meta name="generator" content="xml2rfc version 2.21.0 - https://tools.ietf.org/tools/xml2rfc" />
<link rel="schema.dct" href="http://purl.org/dc/terms/" />
<meta name="dct.creator" content="Reddy, T., Wing, D., Richardson, M., and M. Boucadair" />
<meta name="dct.identifier" content="urn:ietf:id:draft-reddy-dprive-bootstrap-dns-server-01" />
<meta name="dct.issued" scheme="ISO8601" content="2019-03-05" />
<meta name="dct.abstract" content="This document specifies mechanisms to automatically bootstrap endpoints (e.g., hosts, Customer Equipment) to discover and authenticate DNS-over-(D)TLS and DNS-over-HTTPS servers provided by a local network." />
<meta name="description" content="This document specifies mechanisms to automatically bootstrap endpoints (e.g., hosts, Customer Equipment) to discover and authenticate DNS-over-(D)TLS and DNS-over-HTTPS servers provided by a local network." />
</head>
<body>
<table class="header">
<tbody>
<tr>
<td class="left">DPRIVE WG</td>
<td class="right">T. Reddy</td>
</tr>
<tr>
<td class="left">Internet-Draft</td>
<td class="right">McAfee</td>
</tr>
<tr>
<td class="left">Intended status: Standards Track</td>
<td class="right">D. Wing</td>
</tr>
<tr>
<td class="left">Expires: September 6, 2019</td>
<td class="right"></td>
</tr>
<tr>
<td class="left"></td>
<td class="right">M. Richardson</td>
</tr>
<tr>
<td class="left"></td>
<td class="right">Sandelman Software Works</td>
</tr>
<tr>
<td class="left"></td>
<td class="right">M. Boucadair</td>
</tr>
<tr>
<td class="left"></td>
<td class="right">Orange</td>
</tr>
<tr>
<td class="left"></td>
<td class="right">March 5, 2019</td>
</tr>
</tbody>
</table>
<p class="title">A Bootstrapping Procedure to Discover and Authenticate DNS-over-(D)TLS and DNS-over-HTTPS Servers<br />
<span class="filename">draft-reddy-dprive-bootstrap-dns-server-01</span></p>
<h1 id="rfc.abstract"><a href="#rfc.abstract">Abstract</a></h1>
<p>This document specifies mechanisms to automatically bootstrap endpoints (e.g., hosts, Customer Equipment) to discover and authenticate DNS-over-(D)TLS and DNS-over-HTTPS servers provided by a local network.</p>
<h1 id="rfc.status"><a href="#rfc.status">Status of This Memo</a></h1>
<p>This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79.</p>
<p>Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.</p>
<p>Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress."</p>
<p>This Internet-Draft will expire on September 6, 2019.</p>
<h1 id="rfc.copyrightnotice"><a href="#rfc.copyrightnotice">Copyright Notice</a></h1>
<p>Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
<p>This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License.</p>
<hr class="noprint" />
<h1 class="np" id="rfc.toc"><a href="#rfc.toc">Table of Contents</a></h1>
<ul class="toc">
<li>1. <a href="#rfc.section.1">Introduction</a>
</li>
<li>2. <a href="#rfc.section.2">Terminology</a>
</li>
<li>3. <a href="#rfc.section.3">Bootstrapping Endpoint Devices</a>
</li>
<li>4. <a href="#rfc.section.4">Bootstrapping IoT Devices and CPE</a>
</li>
<li>5. <a href="#rfc.section.5">Discovery Procedure</a>
</li>
<ul><li>5.1. <a href="#rfc.section.5.1">Resolution</a>
</li>
</ul><li>6. <a href="#rfc.section.6">Connection handshake and service invocation</a>
</li>
<li>7. <a href="#rfc.section.7">Security Considerations</a>
</li>
<li>8. <a href="#rfc.section.8">IANA Considerations</a>
</li>
<ul><li>8.1. <a href="#rfc.section.8.1">Application Service & Application Protocol Tags</a>
</li>
<ul><li>8.1.1. <a href="#rfc.section.8.1.1">DNS Application Service Tag Registration</a>
</li>
<li>8.1.2. <a href="#rfc.section.8.1.2">dns.tls Application Protocol Tag Registration</a>
</li>
<li>8.1.3. <a href="#rfc.section.8.1.3">dns.dtls Application Protocol Tag Registration</a>
</li>
<li>8.1.4. <a href="#rfc.section.8.1.4">dns.https Application Protocol Tag Registration</a>
</li>
</ul></ul><li>9. <a href="#rfc.section.9">Acknowledgments</a>
</li>
<li>10. <a href="#rfc.references">References</a>
</li>
<ul><li>10.1. <a href="#rfc.references.1">Normative References</a>
</li>
<li>10.2. <a href="#rfc.references.2">Informative References</a>
</li>
</ul><li><a href="#rfc.authors">Authors' Addresses</a>
</li>
</ul>
<h1 id="rfc.section.1">
<a href="#rfc.section.1">1.</a> Introduction</h1>
<p id="rfc.section.1.p.1">Traditionally a caching DNS server has been provided by the local network. This provides several benefits including low latency to that DNS server (due to its network proximity to the endpoint). However, if an endpoint is configured to use Internet-hosted or public DNS-over-(D)TLS <a href="#RFC7858" class="xref">[RFC7858]</a> <a href="#RFC8094" class="xref">[RFC8094]</a> or DNS-over-HTTPS <a href="#RFC8484" class="xref">[RFC8484]</a> servers, the local DNS server cannot serve the DNS requests from the endpoints. If public DNS servers are used instead of using local DNS servers, the operational problems are listed below:</p>
<p></p>
<ul>
<li>"Split DNS" <a href="#RFC2775" class="xref">[RFC2775]</a> to use the special internal-only domain names (e.g., "internal.example.com") in enterprise networks will not work, and ".local" and "home.arpa" names cannot be locally resolved in home networks.</li>
<li>Content Delivery Networks (CDNs) that map traffic based on DNS may lose the ability to direct end-user traffic to a nearby cluster in cases where a DNS service is being used that is not affiliated with the local network and which does not send "EDNS Client Subnet" (ECS) information <a href="#RFC7871" class="xref">[RFC7871]</a> to the CDN's DNS authorities <a href="#CDN" class="xref">[CDN]</a>.</li>
<li>Some clients have pre-configured specific public DNS servers (such as Mozilla using Cloudflare's DNS-over-HTTPS server). If endpoints continue to use hard-coded public DNS servers, this has a risk of relying on few centralized DNS services.</li>
</ul>
<p id="rfc.section.1.p.3">If public DNS servers are used instead of using local DNS servers, the following paragraph discusses the impact on Network-based security:</p>
<p id="rfc.section.1.p.4">Various network security services are provided by Enterprise, secure home and wall-gardened networks to protect endpoints (e.g,. Hosts, IoT devices). <a href="#I-D.camwinget-tls-use-cases" class="xref">[I-D.camwinget-tls-use-cases]</a> discusses some of the Network-based security use cases. These network security services act on DNS requests from endpoints. However, if an endpoint is configured to use public DNS-over-(D)TLS or DNS-over-HTTPS servers, network security services cannot act efficiently on DNS requests from the endpoints. In order to act on DNS requests from endpoints, network security services can block DNS-over-(D)TLS traffic by dropping outgoing packets to destination port 853. Identifying DNS-over-HTTPS traffic is far more challenging than DNS-over-(D)TLS traffic. Network security services can try to identify the domains offering DNS-over-HTTPS servers, and DNS-over-HTTPS traffic can be blocked by dropping outgoing packets to these domains. If the endpoint has enabled strict privacy profile (Section 5 of <a href="#RFC8310" class="xref">[RFC8310]</a>), and the network security service blocks the traffic to the public DNS server, DNS service is not available to the endpoint and ultimately the endpoint cannot access Internet. If the endpoint has enabled opportunistic privacy profile (Section 5 of <a href="#RFC8310" class="xref">[RFC8310]</a>), and the network security service blocks traffic to the public DNS server, the endpoint will either fallback to an encrypted connection without authenticating the DNS server provided by the local network or fallback to clear text DNS, and cannot exchange encrypted DNS messages. This can compromise the endpoint security and privacy; some of the potential privacy and security threats are listed below:</p>
<p></p>
<ul>
<li>Pervasive monitoring of DNS traffic.</li>
<li>If the endpoint is an IoT device which is configured to use public DNS-over-(D)TLS or DNS-over-HTTPS servers, and if a policy enforcement point in the local network is programmed using a Manufacturer Usage Description (MUD) file <a href="#I-D.ietf-opsawg-mud" class="xref">[I-D.ietf-opsawg-mud]</a> by a MUD manager to only allow intented communications to and from the IoT device, the policy enforcement point cannot enforce the Network Access Control List rules based on domain names (Section 8 of <a href="#I-D.ietf-opsawg-mud" class="xref">[I-D.ietf-opsawg-mud]</a>).</li>
<li>The network security service cannot prevent an endpoint from accessing malicious domains. </li>
</ul>
<p id="rfc.section.1.p.6">The DPRIVE and DoH working groups have not yet defined an automated mechanism to securely bootstrap the endpoints to discover and authenticate DNS-over-(D)TLS and DNS-over-HTTPS servers in the local network. The document proposes a mechanism to automatically bootstrap the endpoints to discover and authenticate the DNS-over-(D)TLS and DNS-over-HTTPS servers provided by the local network. The overall procedure can be structured into the following steps:</p>
<ul>
<li>Bootstrapping phase (<a href="#bootstrap-endpoint" class="xref">Section 3</a> and <a href="#bootstrap-iot" class="xref">Section 4</a>) is meant to automatically bootstrap endpoints with local network's CA certificates and DNS server certificate.</li>
<li>Discovery phase (<a href="#discovery" class="xref">Section 5</a>) is meant to discover the privacy-enabling protocols supported by the DNS server and usable DNS server IP addresses and port numbers.</li>
<li>Connection handshake and service invocation: The DNS client initiates (D)TLS handshake with the DNS server learned in the discovery phase. Furthermore, DNS client uses the credentials discovered during the bootstrapping phase to validate the server certificate.</li>
</ul>
<p id="rfc.section.1.p.7">Note: The strict and opportunistic privacy profiles as defined in <a href="#RFC8310" class="xref">[RFC8310]</a> only applies to DNS-over-(D)TLS protocols, there has been no such distinction made for DNS-over-HTTPS protocol. </p>
<h1 id="rfc.section.2">
<a href="#rfc.section.2">2.</a> <a href="#notation" id="notation">Terminology</a>
</h1>
<p id="rfc.section.2.p.1">The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 <a href="#RFC2119" class="xref">[RFC2119]</a><a href="#RFC8174" class="xref">[RFC8174]</a> when, and only when, they appear in all capitals, as shown here.</p>
<p id="rfc.section.2.p.2">(D)TLS is used for statements that apply to both Transport Layer Security <a href="#RFC8446" class="xref">[RFC8446]</a> and Datagram Transport Layer Security <a href="#RFC6347" class="xref">[RFC6347]</a>. Specific terms are used for any statement that applies to either protocol alone.</p>
<p id="rfc.section.2.p.3">This document uses the terms defined in <a href="#RFC8499" class="xref">[RFC8499]</a>.</p>
<h1 id="rfc.section.3">
<a href="#rfc.section.3">3.</a> <a href="#bootstrap-endpoint" id="bootstrap-endpoint">Bootstrapping Endpoint Devices</a>
</h1>
<p id="rfc.section.3.p.1">The following steps explain the mechanism to automatically bootstrap an endpoint with the local network's CA certificates and DNS server certificate: </p>
<p></p>
<ul><li>Bootstrapping Remote Secure Key Infrastructures (BRSKI) discussed in <a href="#I-D.ietf-anima-bootstrapping-keyinfra" class="xref">[I-D.ietf-anima-bootstrapping-keyinfra]</a> provides a solution for secure automated bootstrap of devices. BRSKI specifies means to provision credentials on devices to be used to operationally access networks. In addition, BRSKI provides an automated mechanism for the bootstrap distribution of CA certificates from the EST server. <ol>
<li>The endpoint authenticates to the local network and establishes provisional TLS connection with the registrar operating as the BRSKI-EST server. The endpoint discovers registrar using DNS-based Service Discovery <a href="#RFC6763" class="xref">[RFC6763]</a>.</li>
<li>The endpoint uses Salted Challenge Response Authentication Mechanism (SCRAM) <a href="#RFC7804" class="xref">[RFC7804]</a> to perform mutual authentication with the discovered BRSKI-EST server. SCRAM provides a more robust authentication mechanism than a plaintext password protected by Transport Layer Security (TLS).</li>
<li>If the BRSKI-EST server authentication is successful, the endpoint requests the full EST distribution of current CA certificates and validates the provisional TLS connection to the BRSKI-EST server. If the BRSKI-EST server certificate cannot be verified using the CA certificates downloaded, the TLS connection is immediately discarded and the endpoint abandons the attempt to bootstrap from the BRSKI-EST server and discards the CA certificates conveyed by the BRSKI-EST server. If the BRSKI-EST server certificate is verified using the CA certificates downloaded, the endpoint stores the CA certificates as Explicit Trust Anchor database entries. The endpoint uses the Explicit Trust Anchor database to validate the DNS server certificate. The endpoint needs to perform SCRAM authentication the first time it connects BRSKI-EST server. On subsequent connections to the BRSKI-EST server, the endpoint can validate the BRSKI-EST server certificate using the Explicit Trust Anchor database.</li>
<li>The endpoint learns the End-Entity certificates <a href="#RFC8295" class="xref">[RFC8295]</a> from the BRSKI-EST server. The certificate provisioned to the DNS server in the local network will be treated as a End-Entity certificate. The endpoint needs to identify the certificate provisioned to the DNS server. The SRV-ID identifier type <a href="#RFC6125" class="xref">[RFC6125]</a> within subjectAltName entry can be used to identify the DNS server certificate. For example, DNS server certificate might include SRV-ID "_domain-s.example.net" along with DNS-ID "example.net". This specification defines SRV service label "domain-s" in <a href="#IANA" class="xref">Section 8</a>. As a reminder, the protocol component is not included in the SRV-ID <a href="#RFC4985" class="xref">[RFC4985]</a>.</li>
</ol>
</li></ul>
<h1 id="rfc.section.4">
<a href="#rfc.section.4">4.</a> <a href="#bootstrap-iot" id="bootstrap-iot">Bootstrapping IoT Devices and CPE</a>
</h1>
<p id="rfc.section.4.p.1">The following steps explain the mechanism to automatically bootstrap IoT devices with local network's CA certificates and DNS server certificate. The below steps can also be used by CPE acting as DNS forwarders to discover and authenticate DNS-over-(D)TLS and DNS-over-HTTPS servers provided by the access networks.</p>
<ul><li>The IoT device can use BRSKI discussed in <a href="#I-D.ietf-anima-bootstrapping-keyinfra" class="xref">[I-D.ietf-anima-bootstrapping-keyinfra]</a> to automatically bootstrap the IoT device using the IoT manufacturer provisioned X.509 certificate, in combination with a registrar provided by the local network and IoT device manufacturer's authorizing service (MASA). <ol>
<li>The IoT device authenticates to the local network using the IoT manufacturer provisioned X.509 certificate. The IoT device can request and get a voucher from the MASA service via the registrar. The voucher is signed by the MASA service and includes the local network's CA public key.</li>
<li>The IoT device validates the signed voucher using the manufacturer installed trust anchor associated with the MASA, stores the CA's public key and validates the provisional TLS connection to the registrar.</li>
<li>The IoT device requests the full Enrollment over Secure Transport (EST) <a href="#RFC7030" class="xref">[RFC7030]</a> distribution of current CA certificates (Section 5.9.1 in <a href="#I-D.ietf-anima-bootstrapping-keyinfra" class="xref">[I-D.ietf-anima-bootstrapping-keyinfra]</a>) from the registrar operating as a BRSKI-EST server. The IoT devices stores the CA certificates as Explicit Trust Anchor database entries. The IoT device uses the Explicit Trust Anchor database to validate the DNS server certificate.</li>
<li>The IoT device learns the End-Entity certificates <a href="#RFC8295" class="xref">[RFC8295]</a> from the BRSKI-EST server. The certificate provisioned to the DNS server in the local network will be treated as a End-Entity certificate. The IoT device needs to identify the certificate provisioned to the DNS server. The SRV-ID identifier type <a href="#RFC6125" class="xref">[RFC6125]</a> within subjectAltName entry can be used to identify the DNS server certificate. For example, DNS server certificate might include SRV-ID "_domain-s.example.net" along with DNS-ID "example.net". This specification defines SRV service label "domain-s" in <a href="#IANA" class="xref">Section 8</a>. As a reminder, the protocol component is not included in the SRV-ID <a href="#RFC4985" class="xref">[RFC4985]</a>.</li>
</ol>
</li></ul>
<h1 id="rfc.section.5">
<a href="#rfc.section.5">5.</a> <a href="#discovery" id="discovery">Discovery Procedure</a>
</h1>
<p id="rfc.section.5.p.1">A DNS client discovers the DNS server in the local network supporting DNS-over-TLS, DNS-over-DTLS and DNS-over-HTTPS protocols by using the following discovery mechanism:</p>
<div id="rfc.figure.1"></div>
<div id="fig-naptr-lookup"></div>
<pre> example.net.
IN NAPTR 100 10 "" DPRIVE:dns.tls "" dns1.example.net.
IN NAPTR 200 10 "" DPRIVE:dns.dtls "" dns2.example.net.
dns1.example.net.
IN NAPTR 100 10 S DPRIVE:dns.tls "" _domain-s._tcp.example.net.
dns2.example.net.
IN NAPTR 100 10 S DPRIVE:dns.udp "" _domain-s._udp.example.net.
_domain-s._tcp.example.net.
IN SRV 0 0 853 a.example.net.
_domain-s._udp.example.net.
IN SRV 0 0 853 a.example.net.
a.example.net.
IN A 192.0.2.1
IN AAAA 2001:db8:8:4::2
</pre>
<p></p>
<p></p>
<p class="figure">Figure 1</p>
<div id="rfc.figure.2"></div>
<div id="fig-uri-lookup"></div>
<pre> $ORIGIN example.net.
_domain-s._tcp IN URI 10 1 "https://example.net/dns-query"
</pre>
<p class="figure">Figure 2</p>
<ul>
<li>The DNS client retrieves the authentication domain name for the DNS server from the DNS-ID identifier type within subjectAltName entry in the DNS server certificate.</li>
<li>The DNS client then uses the authentication domain name for S-NAPTR <a href="#RFC3958" class="xref">[RFC3958]</a> lookup to learn the protocols DNS-over-TLS, DNS-over-DTLS, and DNS-over-HTTPS supported by the DNS server and the DNS privacy protocol preferred by the DNS server administrators, as specified in <a href="#srvr" class="xref">Section 5.1</a> and <a href="#tag" class="xref">Section 8.1</a>. This specification adds a SRV service label "domain-s" for privacy-enabling DNS servers. In the example below, for authentication domain name 'example.net', the resolution algorithm will result in the privacy-enabling protocols supported by the DNS server and usable DNS server IP addresses and port numbers.</li>
<li>If DNS-over-HTTPS protocol is supported by the DNS server, the DNS client queries for the URI resource record type <a href="#RFC7553" class="xref">[RFC7553]</a> to use the https URI scheme (Section 3 of <a href="#RFC8484" class="xref">[RFC8484]</a>). In the example below, for authentication domain name 'example.net' and the URL for resolution is https://example.net/dns-query. The following URI resource records could be made available: </li>
</ul>
<h1 id="rfc.section.5.1">
<a href="#rfc.section.5.1">5.1.</a> <a href="#srvr" id="srvr">Resolution</a>
</h1>
<p id="rfc.section.5.1.p.1">Once the DNS client has retrieved the authentication domain name for the DNS server, an S-NAPTR lookup with 'DPRIVE' application service and the desired protocol tag is made to obtain information necessary to securely connect to the DNS server. The S-NAPTR lookup is performed using an recursive DNS resolver discovered from an untrusted source (such as DHCP).</p>
<p id="rfc.section.5.1.p.2">This specification defines "DPRIVE" as an application service tag (<a href="#serviceT" class="xref">Section 8.1.1</a>) and "dns.tls" (<a href="#dnstls" class="xref">Section 8.1.2</a>), "dns.dtls" (<a href="#dnsdtls" class="xref">Section 8.1.3</a>), and "dns.https" (<a href="#dnshttps" class="xref">Section 8.1.4</a>) as application protocol tags.</p>
<p id="rfc.section.5.1.p.3">If no DNS-specific S-NAPTR records can be retrieved, the discovery procedure fails for this authentication domain name. However, before retrying a lookup that has failed, a DNS client MUST wait a time period that is appropriate for the encountered error (e.g., NXDOMAIN, timeout, etc.).</p>
<h1 id="rfc.section.6">
<a href="#rfc.section.6">6.</a> <a href="#auth" id="auth">Connection handshake and service invocation</a>
</h1>
<p id="rfc.section.6.p.1">The DNS client initiates (D)TLS handshake with the DNS server, the server presents its certificate in ServerHello message, and the DNS client matches the DNS server certificate downloaded in step 4 in <a href="#bootstrap-endpoint" class="xref">Section 3</a> and <a href="#bootstrap-iot" class="xref">Section 4</a> with the certificate provided by the DNS server in (D)TLS handshake. If the match is successful, the DNS client validates the server certificate using the Explicit Trust Anchor database entries downloaded in step 3 in <a href="#bootstrap-endpoint" class="xref">Section 3</a> and <a href="#bootstrap-iot" class="xref">Section 4</a>. </p>
<p id="rfc.section.6.p.2">If the match is successful and server certificate is successfully validated, the client continues with the connection as normal. Otherwise, the client MUST treat the server certificate validation failure as a non-recoverable error. If the DNS client cannot reach or establish an authenticated and encrypted connection with the privacy-enabling DNS server provided by the local network, the DNS client can fallback to the privacy-enabling public DNS server.</p>
<h1 id="rfc.section.7">
<a href="#rfc.section.7">7.</a> <a href="#Security" id="Security">Security Considerations</a>
</h1>
<p id="rfc.section.7.p.1">The bootstrapping procedure to discover and authenticate DNS-over-(D)TLS and DNS-over-HTTPS Servers MUST be enabled by the endpoint in a trusted network (e.g. Enterprise, Secure home networks) and disabled in a untrusted network (e.g. Public WiFi network), similar to the way VPN connection from the endpoint to a VPN gateway is disconnected in a trusted network and VPN connection is established in a untrusted network.</p>
<p id="rfc.section.7.p.2">If the endpoint has enabled strict privacy profile, and the network security service blocks the traffic to the privacy-enabling public DNS server, a hard failure occurs and the user is notified. The user has a choice to switch to another network or if the user trusts the network, the user can enable strict privacy profile with the DNS-over-(D)TLS or DNS-over-HTTPS server discovered in the network instead of downgrading to opportunistic privacy profile.</p>
<p id="rfc.section.7.p.3">The primary attacks against the methods described in <a href="#discovery" class="xref">Section 5</a> are the ones that would lead to impersonation of a DNS server and spoofing the DNS response to indicate that the DNS server does not support any privacy-enabling protocols. To protect against DNS-vectored attacks, secured DNS (DNSSEC) can be used to ensure the validity of the DNS records received. The explicit trust anchor database entries downloaded in step 3 in <a href="#bootstrap-endpoint" class="xref">Section 3</a> and <a href="#bootstrap-iot" class="xref">Section 4</a> can be used by the endpoint to validate the DNSSEC signature. Impersonation of the DNS server is prevented by validating the certificate presented by the DNS server. If the BRSKI-EST server conveys the DNS server certificate, but the S-NAPTR lookup indicates that the DNS server does not support any privacy-enabling protocols, the client can detect the DNS response is spoofed. </p>
<p id="rfc.section.7.p.4">Security considerations in <a href="#I-D.ietf-anima-bootstrapping-keyinfra" class="xref">[I-D.ietf-anima-bootstrapping-keyinfra]</a> and <a href="#RFC7804" class="xref">[RFC7804]</a> need to be taken into consideration.</p>
<h1 id="rfc.section.8">
<a href="#rfc.section.8">8.</a> <a href="#IANA" id="IANA">IANA Considerations</a>
</h1>
<p id="rfc.section.8.p.1">IANA is requested to allocate the SRV service name of "domain-s" for DNS-over-(D)TLS and DNS-over-HTTPS. </p>
<h1 id="rfc.section.8.1">
<a href="#rfc.section.8.1">8.1.</a> <a href="#tag" id="tag">Application Service & Application Protocol Tags</a>
</h1>
<p id="rfc.section.8.1.p.1">This document requests IANA to make the following allocations from the registry available at: https://www.iana.org/assignments/s-naptr-parameters/s-naptr-parameters.xhtml.</p>
<h1 id="rfc.section.8.1.1">
<a href="#rfc.section.8.1.1">8.1.1.</a> <a href="#serviceT" id="serviceT">DNS Application Service Tag Registration</a>
</h1>
<p></p>
<ul>
<li>Application Protocol Tag: DPRIVE</li>
<li>Intended Usage: See <a href="#srvr" class="xref">Section 5.1</a>
</li>
<li>Security Considerations: See <a href="#Security" class="xref">Section 7</a>
</li>
<li>Contact Information: <one of the authors></li>
</ul>
<h1 id="rfc.section.8.1.2">
<a href="#rfc.section.8.1.2">8.1.2.</a> <a href="#dnstls" id="dnstls">dns.tls Application Protocol Tag Registration</a>
</h1>
<p></p>
<ul>
<li>Application Protocol Tag: dns.tls</li>
<li>Intended Usage: See <a href="#srvr" class="xref">Section 5.1</a>
</li>
<li>Security Considerations: See <a href="#Security" class="xref">Section 7</a>
</li>
<li>Contact Information: <one of the authors></li>
</ul>
<h1 id="rfc.section.8.1.3">
<a href="#rfc.section.8.1.3">8.1.3.</a> <a href="#dnsdtls" id="dnsdtls">dns.dtls Application Protocol Tag Registration</a>
</h1>
<p></p>
<ul>
<li>Application Protocol Tag: dns.dtls</li>
<li>Intended Usage: See <a href="#srvr" class="xref">Section 5.1</a>
</li>
<li>Security Considerations: See <a href="#Security" class="xref">Section 7</a>
</li>
<li>Contact Information: <one of the authors></li>
</ul>
<h1 id="rfc.section.8.1.4">
<a href="#rfc.section.8.1.4">8.1.4.</a> <a href="#dnshttps" id="dnshttps">dns.https Application Protocol Tag Registration</a>
</h1>
<p></p>
<ul>
<li>Application Protocol Tag: dnshttps</li>
<li>Intended Usage: See <a href="#srvr" class="xref">Section 5.1</a>
</li>
<li>Security Considerations: See <a href="#Security" class="xref">Section 7</a>
</li>
<li>Contact Information: <one of the authors></li>
</ul>
<h1 id="rfc.section.9">
<a href="#rfc.section.9">9.</a> <a href="#acknowledgments" id="acknowledgments">Acknowledgments</a>
</h1>
<p id="rfc.section.9.p.1">Thanks to Joe Hildebrand, Harsha Joshi, Shashank Jain, Patrick McManus and Sara Dickinson for the discussion and comments.</p>
<h1 id="rfc.references">
<a href="#rfc.references">10.</a> References</h1>
<h1 id="rfc.references.1">
<a href="#rfc.references.1">10.1.</a> Normative References</h1>
<table><tbody>
<tr>
<td class="reference"><b id="I-D.ietf-anima-bootstrapping-keyinfra">[I-D.ietf-anima-bootstrapping-keyinfra]</b></td>
<td class="top">
<a>Pritikin, M.</a>, <a>Richardson, M.</a>, <a>Behringer, M.</a>, <a>Bjarnason, S.</a> and <a>K. Watsen</a>, "<a href="https://tools.ietf.org/html/draft-ietf-anima-bootstrapping-keyinfra-19">Bootstrapping Remote Secure Key Infrastructures (BRSKI)</a>", Internet-Draft draft-ietf-anima-bootstrapping-keyinfra-19, March 2019.</td>
</tr>
<tr>
<td class="reference"><b id="RFC2119">[RFC2119]</b></td>
<td class="top">
<a>Bradner, S.</a>, "<a href="https://tools.ietf.org/html/rfc2119">Key words for use in RFCs to Indicate Requirement Levels</a>", BCP 14, RFC 2119, DOI 10.17487/RFC2119, March 1997.</td>
</tr>
<tr>
<td class="reference"><b id="RFC3958">[RFC3958]</b></td>
<td class="top">
<a>Daigle, L.</a> and <a>A. Newton</a>, "<a href="https://tools.ietf.org/html/rfc3958">Domain-Based Application Service Location Using SRV RRs and the Dynamic Delegation Discovery Service (DDDS)</a>", RFC 3958, DOI 10.17487/RFC3958, January 2005.</td>
</tr>
<tr>
<td class="reference"><b id="RFC4985">[RFC4985]</b></td>
<td class="top">
<a>Santesson, S.</a>, "<a href="https://tools.ietf.org/html/rfc4985">Internet X.509 Public Key Infrastructure Subject Alternative Name for Expression of Service Name</a>", RFC 4985, DOI 10.17487/RFC4985, August 2007.</td>
</tr>
<tr>
<td class="reference"><b id="RFC6125">[RFC6125]</b></td>
<td class="top">
<a>Saint-Andre, P.</a> and <a>J. Hodges</a>, "<a href="https://tools.ietf.org/html/rfc6125">Representation and Verification of Domain-Based Application Service Identity within Internet Public Key Infrastructure Using X.509 (PKIX) Certificates in the Context of Transport Layer Security (TLS)</a>", RFC 6125, DOI 10.17487/RFC6125, March 2011.</td>
</tr>
<tr>
<td class="reference"><b id="RFC6347">[RFC6347]</b></td>
<td class="top">
<a>Rescorla, E.</a> and <a>N. Modadugu</a>, "<a href="https://tools.ietf.org/html/rfc6347">Datagram Transport Layer Security Version 1.2</a>", RFC 6347, DOI 10.17487/RFC6347, January 2012.</td>
</tr>
<tr>
<td class="reference"><b id="RFC6763">[RFC6763]</b></td>
<td class="top">
<a>Cheshire, S.</a> and <a>M. Krochmal</a>, "<a href="https://tools.ietf.org/html/rfc6763">DNS-Based Service Discovery</a>", RFC 6763, DOI 10.17487/RFC6763, February 2013.</td>
</tr>
<tr>
<td class="reference"><b id="RFC7030">[RFC7030]</b></td>
<td class="top">
<a>Pritikin, M.</a>, <a>Yee, P.</a> and <a>D. Harkins</a>, "<a href="https://tools.ietf.org/html/rfc7030">Enrollment over Secure Transport</a>", RFC 7030, DOI 10.17487/RFC7030, October 2013.</td>
</tr>
<tr>
<td class="reference"><b id="RFC7553">[RFC7553]</b></td>
<td class="top">
<a>Faltstrom, P.</a> and <a>O. Kolkman</a>, "<a href="https://tools.ietf.org/html/rfc7553">The Uniform Resource Identifier (URI) DNS Resource Record</a>", RFC 7553, DOI 10.17487/RFC7553, June 2015.</td>
</tr>
<tr>
<td class="reference"><b id="RFC7804">[RFC7804]</b></td>
<td class="top">
<a>Melnikov, A.</a>, "<a href="https://tools.ietf.org/html/rfc7804">Salted Challenge Response HTTP Authentication Mechanism</a>", RFC 7804, DOI 10.17487/RFC7804, March 2016.</td>
</tr>
<tr>
<td class="reference"><b id="RFC7858">[RFC7858]</b></td>
<td class="top">
<a>Hu, Z.</a>, <a>Zhu, L.</a>, <a>Heidemann, J.</a>, <a>Mankin, A.</a>, <a>Wessels, D.</a> and <a>P. Hoffman</a>, "<a href="https://tools.ietf.org/html/rfc7858">Specification for DNS over Transport Layer Security (TLS)</a>", RFC 7858, DOI 10.17487/RFC7858, May 2016.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8094">[RFC8094]</b></td>
<td class="top">
<a>Reddy, T.</a>, <a>Wing, D.</a> and <a>P. Patil</a>, "<a href="https://tools.ietf.org/html/rfc8094">DNS over Datagram Transport Layer Security (DTLS)</a>", RFC 8094, DOI 10.17487/RFC8094, February 2017.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8174">[RFC8174]</b></td>
<td class="top">
<a>Leiba, B.</a>, "<a href="https://tools.ietf.org/html/rfc8174">Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words</a>", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8295">[RFC8295]</b></td>
<td class="top">
<a>Turner, S.</a>, "<a href="https://tools.ietf.org/html/rfc8295">EST (Enrollment over Secure Transport) Extensions</a>", RFC 8295, DOI 10.17487/RFC8295, January 2018.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8446">[RFC8446]</b></td>
<td class="top">
<a>Rescorla, E.</a>, "<a href="https://tools.ietf.org/html/rfc8446">The Transport Layer Security (TLS) Protocol Version 1.3</a>", RFC 8446, DOI 10.17487/RFC8446, August 2018.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8484">[RFC8484]</b></td>
<td class="top">
<a>Hoffman, P.</a> and <a>P. McManus</a>, "<a href="https://tools.ietf.org/html/rfc8484">DNS Queries over HTTPS (DoH)</a>", RFC 8484, DOI 10.17487/RFC8484, October 2018.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8499">[RFC8499]</b></td>
<td class="top">
<a>Hoffman, P.</a>, <a>Sullivan, A.</a> and <a>K. Fujiwara</a>, "<a href="https://tools.ietf.org/html/rfc8499">DNS Terminology</a>", BCP 219, RFC 8499, DOI 10.17487/RFC8499, January 2019.</td>
</tr>
</tbody></table>
<h1 id="rfc.references.2">
<a href="#rfc.references.2">10.2.</a> Informative References</h1>
<table><tbody>
<tr>
<td class="reference"><b id="CDN">[CDN]</b></td>
<td class="top">"<a href="https://conferences.sigcomm.org/sigcomm/2015/pdf/papers/p167.pdf">End-User Mapping: Next Generation Request Routing for Content Delivery</a>", 2015.</td>
</tr>
<tr>
<td class="reference"><b id="I-D.camwinget-tls-use-cases">[I-D.camwinget-tls-use-cases]</b></td>
<td class="top">
<a>Andreasen, F.</a>, <a>Cam-Winget, N.</a> and <a>E. Wang</a>, "<a href="https://tools.ietf.org/html/draft-camwinget-tls-use-cases-03">TLS 1.3 Impact on Network-Based Security</a>", Internet-Draft draft-camwinget-tls-use-cases-03, December 2018.</td>
</tr>
<tr>
<td class="reference"><b id="I-D.ietf-opsawg-mud">[I-D.ietf-opsawg-mud]</b></td>
<td class="top">
<a>Lear, E.</a>, <a>Droms, R.</a> and <a>D. Romascanu</a>, "<a href="https://tools.ietf.org/html/draft-ietf-opsawg-mud-25">Manufacturer Usage Description Specification</a>", Internet-Draft draft-ietf-opsawg-mud-25, June 2018.</td>
</tr>
<tr>
<td class="reference"><b id="RFC2775">[RFC2775]</b></td>
<td class="top">
<a>Carpenter, B.</a>, "<a href="https://tools.ietf.org/html/rfc2775">Internet Transparency</a>", RFC 2775, DOI 10.17487/RFC2775, February 2000.</td>
</tr>
<tr>
<td class="reference"><b id="RFC7871">[RFC7871]</b></td>
<td class="top">
<a>Contavalli, C.</a>, <a>van der Gaast, W.</a>, <a>Lawrence, D.</a> and <a>W. Kumari</a>, "<a href="https://tools.ietf.org/html/rfc7871">Client Subnet in DNS Queries</a>", RFC 7871, DOI 10.17487/RFC7871, May 2016.</td>
</tr>
<tr>
<td class="reference"><b id="RFC8310">[RFC8310]</b></td>
<td class="top">
<a>Dickinson, S.</a>, <a>Gillmor, D.</a> and <a>T. Reddy</a>, "<a href="https://tools.ietf.org/html/rfc8310">Usage Profiles for DNS over TLS and DNS over DTLS</a>", RFC 8310, DOI 10.17487/RFC8310, March 2018.</td>
</tr>
</tbody></table>
<h1 id="rfc.authors"><a href="#rfc.authors">Authors' Addresses</a></h1>
<div class="avoidbreak">
<address class="vcard">
<span class="vcardline">
<span class="fn">Tirumaleswar Reddy</span>
<span class="n hidden">
<span class="family-name">Reddy</span>
</span>
</span>
<span class="org vcardline">McAfee, Inc.</span>
<span class="adr">
<span class="vcardline">Embassy Golf Link Business Park</span>
<span class="vcardline">
<span class="locality">Bangalore</span>,
<span class="region">Karnataka</span>
<span class="code">560071</span>
</span>
<span class="country-name vcardline">India</span>
</span>
<span class="vcardline">EMail: <a href="mailto:kondtir@gmail.com">kondtir@gmail.com</a></span>
</address>
</div><div class="avoidbreak">
<address class="vcard">
<span class="vcardline">
<span class="fn">Dan Wing</span>
<span class="n hidden">
<span class="family-name">Wing</span>
</span>
</span>
<span class="org vcardline"></span>
<span class="adr">
<span class="vcardline">
<span class="locality"></span>
<span class="region"></span>
<span class="code"></span>
</span>
<span class="country-name vcardline">USA</span>
</span>
<span class="vcardline">EMail: <a href="mailto:dan@danwing.org">dan@danwing.org</a></span>
</address>
</div><div class="avoidbreak">
<address class="vcard">
<span class="vcardline">
<span class="fn">Michael C. Richardson</span>
<span class="n hidden">
<span class="family-name">Richardson</span>
</span>
</span>
<span class="org vcardline">Sandelman Software Works</span>
<span class="adr">
<span class="vcardline">
<span class="locality"></span>
<span class="region"></span>
<span class="code"></span>
</span>
<span class="country-name vcardline">USA</span>
</span>
<span class="vcardline">EMail: <a href="mailto:mcr+ietf@sandelman.ca">mcr+ietf@sandelman.ca</a></span>
</address>
</div><div class="avoidbreak">
<address class="vcard">
<span class="vcardline">
<span class="fn">Mohamed Boucadair</span>
<span class="n hidden">
<span class="family-name">Boucadair</span>
</span>
</span>
<span class="org vcardline">Orange</span>
<span class="adr">
<span class="vcardline">
<span class="locality">Rennes</span>,
<span class="region"></span>
<span class="code">35000</span>
</span>
<span class="country-name vcardline">France</span>
</span>
<span class="vcardline">EMail: <a href="mailto:mohamed.boucadair@orange.com">mohamed.boucadair@orange.com</a></span>
</address>
</div>
</body>
</html>