MUD (D)TLS profiles for IoT devices
draft-reddy-opsawg-mud-tls-00
The information below is for an old version of the document.
| Document | Type |
This is an older version of an Internet-Draft whose latest revision state is "Replaced".
|
|
|---|---|---|---|
| Authors | Tirumaleswar Reddy.K , Dan Wing | ||
| Last updated | 2019-08-06 | ||
| Replaced by | draft-ietf-opsawg-mud-tls | ||
| RFC stream | (None) | ||
| Formats | |||
| Additional resources | |||
| Stream | Stream state | (No stream defined) | |
| Consensus boilerplate | Unknown | ||
| RFC Editor Note | (None) | ||
| IESG | IESG state | I-D Exists | |
| Telechat date | (None) | ||
| Responsible AD | (None) | ||
| Send notices to | (None) |
draft-reddy-opsawg-mud-tls-00
OPSWG WG T. Reddy
Internet-Draft McAfee
Intended status: Standards Track D. Wing
Expires: February 7, 2020 Citrix
August 6, 2019
MUD (D)TLS profiles for IoT devices
draft-reddy-opsawg-mud-tls-00
Abstract
This memo extends Manufacturer Usage Description (MUD) to model DTLS
and TLS usage. This allows a network element to notice abnormal DTLS
or TLS usage which has been strong indicator of other software
running on the endpoint, typically malware.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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/.
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."
This Internet-Draft will expire on February 7, 2020.
Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved.
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.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Overview of MUD (D)TLS profiles for IoT devices . . . . . . . 4
4. (D)TLS profile YANG module . . . . . . . . . . . . . . . . . 5
4.1. Tree Structure . . . . . . . . . . . . . . . . . . . . . 6
4.2. YANG Module . . . . . . . . . . . . . . . . . . . . . . . 7
5. (D)TLS 1.3 handshake . . . . . . . . . . . . . . . . . . . . 11
5.1. Encrypted SNI . . . . . . . . . . . . . . . . . . . . . . 11
5.2. Full (D)TLS 1.3 handshake inspection . . . . . . . . . . 12
6. MUD File Example . . . . . . . . . . . . . . . . . . . . . . 13
7. Security Considerations . . . . . . . . . . . . . . . . . . . 14
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 14
10.1. Normative References . . . . . . . . . . . . . . . . . . 14
10.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16
1. Introduction
Encryption is necessary to protect the privacy of end users using IoT
devices. In a network setting, TLS [RFC8446] and DTLS
[I-D.ietf-tls-dtls13] are the dominant protocols to provide
encryption for IoT device traffic. Unfortunately in conjunction with
IoT applications rise of encryption, malware is also using encryption
which thwarts network-based analysis such as deep packet inspection
(DPI). Other mechanisms are needed to notice malware is running on
the IoT device.
Malware frequently uses its own libraries for its activities, and
those libraries are re-used much like any other software engineering
project. Research [malware] indicates there are observable
differences in how malware uses encryption compared with non-malware
uses encryption. There are several interesting findings specific to
DTLS and TLS which were found common to malware:
o Older and weaker cryptographic parameters (e.g.,
TLS_RSA_WITH_RC4_128_SHA).
o TLS SNI and server certificates are composed of subjects with
characteristics of a domain generation algorithm (DGA) (e.g.,
www.33mhwt2j.net).
o Higher use of self-signed certificates compared with typical
legitimate software.
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o Discrepancies in the server name indication (SNI) TLS extension in
the ClientHello message and the DNS names in the
SubjectAltName(SAN) X.509 extension in the server certificate
message.
o Discrepancies in the key exchange algorithm and the client public
key length in comparison with legitimate flows. As a reminder,
Client Key Exchange message has been removed from TLS 1.3.
o Lower diversity in TLS client advertised TLS extensions compared
to legitimate clients.
If observable (D)TLS profile parameters are used, the following
discusses the favorable impact on network security:
o Although IoT devices that have a single or small number of uses
might have very broad communication patterns. In such a case, MUD
rules using ACLs on its own is not suitable for these IoT devices
but observable (D)TLS profile parameters can be used for such IoT
devices to permit intended use and to block malicious behaviour of
IoT devices.
o Several TLS deployments have been vulnerable to active Man-In-The-
Middle (MITM) attacks because of lack of certificate validation.
By observing (D)TLS profile parameters, a network element can
detect when the TLS SNI mismatches the SubjectAltName and detect
when the server's certificate is invalid, and alert those
situations.
o IoT device can learn a new skill, and the new skill changes the
way the IoT device communicates with other devices located in the
local network and Internet. In other words, if IP addresses and
domain names the IoT device connects to rapidly changes and MUD
rules using ACLs cannot be rapidly updated, observable (D)TLS
profile parameters can be used to permit intended use and to block
malicious behaviour of IoT device.
This document extends MUD [RFC8520] to model observable (D)TLS
profile parameters. Using these (D)TLS profile parameters, an active
MUD-enforcing firewall can identify MUD non-compliant DTLS and TLS
behavior that can indicate malware is running on the IoT device.
This detection can prevent malware download, block access to
malicious domains, enforce use of strong ciphers, stop data
exfiltration, etc. In addition, organizations may have policies
around acceptable ciphers and certificates on the websites the IoT
devices connect to. Examples include no use of old and less secure
versions of TLS, no use of self-signed certificates, deny-list or
accept-list of Certificate Authorities, valid certificate expiration
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time, etc. These policies can be enforced by observing the (D)TLS
profile parameters. Enterprise firewall can use the IoT device's
(D)TLS profile parameters to identify legitimate flows by observation
of (D)TLS sessions, and can make inferences to permit legitimate
flows and to block malicious flows. The proposed technique is also
suitable in deployments where decryption techniques are not ideal due
to privacy concerns, non-cooperating end-points and expense.
2. Terminology
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 [RFC2119][RFC8174] when, and only when, they appear in all
capitals, as shown here.
"(D)TLS" is used for statements that apply to both Transport Layer
Security [RFC8446] and Datagram Transport Layer Security [RFC6347].
Specific terms are used for any statement that applies to either
protocol alone.
3. Overview of MUD (D)TLS profiles for IoT devices
In Enterprise networks, protection and detection are typically done
both on end hosts and in the network. Host agents have deep
visibility on the devices where they are installed, whereas the
network has broader visibility. Installing host agents may not be a
viable option on IoT devices, and network-based security can only be
used to protect such IoT devices. (D)TLS profile parameters of IoT
device can be used by middle-boxes to detect and block malware
communication, while at the same time preserving the privacy of
legitimate uses of encryption. Middle-boxes need not proxy (D)TLS
but can passively observe the parameters of (D)TLS handshakes from
IoT devices and gain good visibility into TLS 1.0 to 1.2 parameters
and partial visibility into TLS 1.3 parameters. Malicious agents can
try to use the (D)TLS profile parameters as legitimate agents to
evade detection but it becomes a challenge to mimic the behavior of
various IoT device types and IoT device models from several
manufacturers. In other words, malware developers will have to
develop malicious agents per IoT device type, manufacturer and model
(which will be several thousands), infect the device with specific
malware agent and will have keep up with the updates to (D)TLS
profile parameters of IoT devices. Further, the malware command and
control server certificates needs to be signed by the same certifying
authorities trusted by the IoT devices.
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4. (D)TLS profile YANG module
This document specifies a YANG module for representing (D)TLS
profile. The (D)TLS profile YANG module provides a method for
firewall to observe the (D)TLS profile parameters in the (D)TLS
handshake to permit intended use and to block malicious behavior.
This module uses the common YANG types defined in [RFC6991] , rules
defined in [RFC8519] and cryptographic types defined in
[I-D.ietf-netconf-crypto-types].
The (D)TLS profiles and the parameters in each (D)TLS profile include
the following:
o Profile name
o (D)TLS version in ClientHello.legacy_version
o (D)TLS versions supported by the IoT device. As a reminder,
"supported_versions" extension defined in (D)TLS 1.3 is used by
the client to indicate which versions of (D)TLS it supports and a
client is considered to be attempting to negotiate (D)TLS 1.3 if
the ClientHello contains a "supported_versions" extension with
0x0304 contained in its body.
o If GREASE [I-D.ietf-tls-grease] (Generate Random Extensions And
Sustain Extensibility) values are offered by the client or not.
o List of supported symmetric encryption algorithms
o List of supported compression methods
o List of extension types
o List of trust anchor certificates used by the IoT device. Note
that server certificate is encrypted in (D)TLS 1.3 and the middle-
box without acting as (D)TLS proxy cannot validate the server
certificate.
o List of SPKI pin sets pre-configured on the client to validate
self-signed server certificates or raw public keys
o Cryptographic hash algorithm used to generate the SPKI pinsets
o List of pre-shared key exchange modes
o List of DHE or ECDHE groups supported by the client
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o List signature algorithms the client can validate in X.509 server
certificates
o List of client key exchange algorithms and the client public key
lengths in versions prior to (D)TLS 1.3
The (D)TLS profile parameters MUST NOT include the GREASE values for
extension types, supported groups, signature algorithms, (D)TLS
versions, pre-shared key exchange modes and cipher suites. Note that
the GREASE values are random and peers will ignore these values and
interoperate.
If the (D)TLS profile parameters are not observed in a (D)TLS session
from the IoT device, the default behaviour is to block the (D)TLS
session.
4.1. Tree Structure
This document augments the "ietf-mud" MUD YANG module defined in
[RFC8520] for signaling the IoT device (D)TLS profile. This document
defines the YANG module "reddy-opsawg-mud-tls-profile", which has the
following tree structure:
module: reddy-opsawg-mud-tls-profile
augment /mud:mud/mud:from-device-policy:
+--rw client-profile
+--rw tls-profiles* [profile-name]
+--rw profile-name string
+--rw protocol-version? uint16
+--rw supported_versions* uint16
+--rw grease_extension? boolean
+--rw encryption-algorithms* encryption-algorithm
+--rw compression-methods* compression-method
+--rw extension-types* extension-type
+--rw acceptlist-ta-certs* ct:trust-anchor-cert-cms
+--rw SPKI-pin-sets* SPKI-pin-set
+--rw SPKI-hash-algorithm ct:hash-algorithm-t
+--rw psk-key-exchange-modes* psk-key-exchange-mode
+--rw supported-groups* supported-group
+--rw signature-algorithms* signature-algorithm
+--rw client-public-keys
| +--rw key-exchange-algorithms* key-exchange-algorithm
| +--rw client-public-key-lengths* client-public-key-length
+--rw actions
+--rw forwarding identityref
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4.2. YANG Module
module reddy-opsawg-mud-tls-profile {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:reddy-opsawg-mud-tls-profile";
prefix mud-tls-profile;
import ietf-crypto-types {
prefix ct;
reference "draft-ietf-netconf-crypto-types-01:
Common YANG Data Types for Cryptography";
}
import ietf-inet-types {
prefix inet;
reference "Section 4 of RFC 6991";
}
import ietf-mud {
prefix mud;
reference "RFC 8520";
}
import ietf-access-control-list {
prefix ietf-acl;
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
organization
"IETF Operations and Management Area Working Group Working Group";
contact
"Editor: Konda, Tirumaleswar Reddy
<mailto:TirumaleswarReddy_Konda@McAfee.com>";
description
"This module contains YANG definition for configuring
aliases for resources and filtering rules using DOTS
data channel.
Copyright (c) 2019 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
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set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
revision 2019-06-12 {
description
"Initial revision.";
}
typedef compression-method {
type uint8;
description "Compression method.";
}
typedef extension-type {
type uint16;
description "Extension type.";
}
typedef encryption-algorithm {
type uint16;
description "Encryption algorithms.";
}
typedef supported-group {
type uint16;
description "supported DHE or ECDHE group.";
}
typedef SPKI-pin-set {
type binary;
description "Subject Public Key Info pin set.";
}
typedef signature-algorithm {
type uint16;
description "Signature algorithm";
}
typedef key-exchange-algorithm {
type uint8;
description "key exchange algorithm";
}
typedef psk-key-exchange-mode {
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type uint8;
description "pre-shared key exchange mode";
}
typedef client-public-key-length {
type uint8;
description "client public key length";
}
augment "/mud:mud/mud:from-device-policy" {
container client-profile {
list tls-profiles {
key "profile-name";
description
"(D)TLS version profiles supported by the client";
leaf profile-name {
type string {
length "1..64";
}
description
"The name of (D)TLS profile; space and special
characters are not allowed.";
}
leaf protocol-version {
type uint16;
description "Legacy protocol version.";
}
leaf-list supported_versions {
type uint16;
description
"TLS versions supported by the client indicated
in the supported_versions extension in (D)TLS 1.3.";
}
leaf Grease_extension {
type boolean;
description
"If set to 'true', Grease extension values are offered by
the client.";
}
leaf-list encryption-algorithms {
type encryption-algorithm;
description "Encryption algorithms";
}
leaf-list compression-methods {
type compression-method;
description "Compression methods";
}
leaf-list extension-types {
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type extension-type;
description "Extension Types";
}
leaf-list acceptlist-ta-certs {
type ct:trust-anchor-cert-cms;
description
"A list of trust anchor certificates used by the client.";
}
leaf-list SPKI-pin-sets {
type SPKI-pin-set;
description
"A list of SPKI pin sets pre-configured on the client
to validate self-signed server certificate or
raw public key.";
}
leaf SPKI-hash-algorithm {
type ct:hash-algorithm-t;
description
"cryptographic hash algorithm used to generate the
SPKI pinset.";
}
leaf-list psk-key-exchange-modes {
type psk-key-exchange-mode;
description
"pre-shared key exchange modes";
}
leaf-list supported-groups {
type supported-group;
description
"A list of DHE or ECDHE groups supported by the client.";
}
leaf-list signature-algorithms {
type signature-algorithm;
description
"A list signature algorithms the client can validate
in X.509 certificates.";
}
container client-public-keys {
leaf-list key-exchange-algorithms {
type key-exchange-algorithm;
description
"Key exchange algorithms supported by the client";
}
leaf-list client-public-key-lengths {
type client-public-key-length;
description
"client public key lengths";
}
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}
container actions {
description
"Definitions of action for this profile.";
leaf forwarding {
type identityref {
base ietf-acl:forwarding-action;
}
mandatory true;
description
"Specifies the forwarding action for the (D)TLS profile.";
reference
"RFC 8519: YANG Data Model for Network Access
Control Lists (ACLs)";
}
}
}
}
}
}
5. (D)TLS 1.3 handshake
In (D)TLS 1.3, full (D)TLS handshake inspection is not possible since
all (D)TLS handshake messages excluding the ClientHello message are
encrypted. (D)TLS 1.3 has introduced new extensions in the handshake
record layers called Encrypted Extensions. Using these extensions
handshake messages will be encrypted and network devices (such as a
firewall) are incapable deciphering the handshake, thus cannot view
the server certificate. However, a few parameters in the ServerHello
are still visible such as the chosen cipher. Note that Client Key
Exchange message has been removed from (D)TLS 1.3.
5.1. Encrypted SNI
To increase privacy, encrypted SNI [I-D.ietf-tls-sni-encryption]
prevents passive observation of the TLS Server Name Indication and to
effectively provide privacy protection, SNI encryption needs to be
used in conjunction with DNS encryption (e.g., DNS-over-(D)TLS or
DNS- over-HTTPS). Firewall inspecting the (D)TLS 1.3 handshake
cannot decrypt encrypted SNI. If an IoT device is configured to use
public DNS-over-(D)TLS or DNS- over-HTTPS servers, the policy
enforcement point is moved to that public server, which cannot
enforce the MUD policy based on domain names (Section 8 of
[RFC8520]). Thus the use of a public DNS-over-(D)TLS or DNS- over-
HTTPS server is incompatible with MUD. A local DNS server is
necessary to allow MUD policy enforcement on the local network
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([I-D.ietf-doh-resolver-associated-doh] and
[I-D.reddy-dprive-bootstrap-dns-server]).
5.2. Full (D)TLS 1.3 handshake inspection
Middle-box needs to act as a (D)TLS 1.3 proxy to observe the
parameters of (D)TLS handshakes from IoT devices and gain good
visibility into TLS 1.3 parameters. The following steps explain the
mechanism to automatically bootstrap IoT devices with local network's
CA certificates and to enable the middle-box to act as a (D)TLS 1.3
proxy.
o Bootstrapping Remote Secure Key Infrastructures (BRSKI) discussed
in [I-D.ietf-anima-bootstrapping-keyinfra] 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 Enrollment over Secure Transport (EST) [RFC7030] server. The
IoT device can use BRSKI 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).
1. 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.
2. 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.
3. The IoT device requests the full EST distribution of current
CA certificates (Section 5.9.1 in
[I-D.ietf-anima-bootstrapping-keyinfra]) from the registrar
operating as a BRSKI-EST server. The IoT device stores the CA
certificates as Explicit Trust Anchor database entries. The
IoT device uses the Explicit Trust Anchor database to validate
the server certificate.
4. The middle-box uses the "supported_versions" TLS extension
(defined in TLS 1.3 to negotiate the supported TLS versions
between client and server) to determine the TLS version.
During the (D)TLS handshake, If (D)TLS version 1.3 is used,
the middle-box ((D)TLS proxy) modifies the certificate
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provided by the server and signs it with the private key from
the local CA certificate. The middle-box has visibility into
further exchanges between the IoT device and server which
enables it to inspect the (D)TLS 1.3 handshake, enforce the
MUD (D)TLS profile and can inspect subsequent network traffic.
5. The IoT device uses the Explicit Trust Anchor database to
validate the server certificate.
The proposed technique empowers the middle-box to reject (D)TLS 1.3
sessions that violate the MUD (D)TLS profile.
6. MUD File Example
This example below contains (D)TLS profile parameters for a IoT
device. JSON encoding of YANG modelled data [RFC7951] is used to
illustrate the example.
{
"ietf-mud:mud": {
"mud-version": 1,
"mud-url": "https://example.com/IoTDevice",
"last-update": "2019-18-06T03:56:40.105+10:00",
"cache-validity": 100,
"is-supported": true,
"systeminfo": "IoT device name",
"reddy-opsawg-mud-tls-profile:from-device-policy": {
"client-profile": {
"tls-version-profile" : [
{
"protocol-version" : 771,
"supported_versions_ext" : "FALSE",
"encryption-algorithms" : [31354, 4865, 4866, 4867],
"extension-types" : [10],
"supported-groups" : [29],
"actions": {
"forwarding": "accept"
}
}
]
}
}
}
}
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7. Security Considerations
Security considerations in [RFC8520] need to be taken into
consideration.
8. IANA Considerations
This document requests IANA to register the following URIs in the
"ns" subregistry within the "IETF XML Registry" [RFC3688]:
URI: urn:ietf:params:xml:ns:yang:reddy-opsawg-mud-tls-profile
Registrant Contact: The IESG.
XML: N/A; the requested URI is an XML namespace.
9. Acknowledgments
Thanks to Shashank Jain and Harsha Joshi for the discussion and
comments.
10. References
10.1. Normative References
[I-D.ietf-netconf-crypto-types]
Watsen, K. and H. Wang, "Common YANG Data Types for
Cryptography", draft-ietf-netconf-crypto-types-10 (work in
progress), July 2019.
[I-D.ietf-tls-dtls13]
Rescorla, E., Tschofenig, H., and N. Modadugu, "The
Datagram Transport Layer Security (DTLS) Protocol Version
1.3", draft-ietf-tls-dtls13-32 (work in progress), July
2019.
[I-D.ietf-tls-grease]
Benjamin, D., "Applying GREASE to TLS Extensibility",
draft-ietf-tls-grease-03 (work in progress), July 2019.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC3688] Mealling, M., "The IETF XML Registry", BCP 81, RFC 3688,
DOI 10.17487/RFC3688, January 2004,
<https://www.rfc-editor.org/info/rfc3688>.
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[RFC6347] Rescorla, E. and N. Modadugu, "Datagram Transport Layer
Security Version 1.2", RFC 6347, DOI 10.17487/RFC6347,
January 2012, <https://www.rfc-editor.org/info/rfc6347>.
[RFC6991] Schoenwaelder, J., Ed., "Common YANG Data Types",
RFC 6991, DOI 10.17487/RFC6991, July 2013,
<https://www.rfc-editor.org/info/rfc6991>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8446] Rescorla, E., "The Transport Layer Security (TLS) Protocol
Version 1.3", RFC 8446, DOI 10.17487/RFC8446, August 2018,
<https://www.rfc-editor.org/info/rfc8446>.
[RFC8519] Jethanandani, M., Agarwal, S., Huang, L., and D. Blair,
"YANG Data Model for Network Access Control Lists (ACLs)",
RFC 8519, DOI 10.17487/RFC8519, March 2019,
<https://www.rfc-editor.org/info/rfc8519>.
10.2. Informative References
[I-D.ietf-anima-bootstrapping-keyinfra]
Pritikin, M., Richardson, M., Behringer, M., and K.
Watsen, "Bootstrapping Remote Secure Key Infrastructures
(BRSKI)", draft-ietf-anima-bootstrapping-keyinfra-24 (work
in progress), July 2019.
[I-D.ietf-doh-resolver-associated-doh]
Hoffman, P., "Associating a DoH Server with a Resolver",
draft-ietf-doh-resolver-associated-doh-03 (work in
progress), March 2019.
[I-D.ietf-tls-sni-encryption]
Huitema, C. and E. Rescorla, "Issues and Requirements for
SNI Encryption in TLS", draft-ietf-tls-sni-encryption-04
(work in progress), November 2018.
[I-D.reddy-dprive-bootstrap-dns-server]
K, R., Wing, D., Richardson, M., and M. Boucadair, "A
Bootstrapping Procedure to Discover and Authenticate DNS-
over-(D)TLS and DNS-over-HTTPS Servers", draft-reddy-
dprive-bootstrap-dns-server-04 (work in progress), June
2019.
Reddy & Wing Expires February 7, 2020 [Page 15]
Internet-Draft MUD TLS profile for IoT devices August 2019
[malware] Anderson, B., Paul, S., and D. McGrew, "Deciphering
Malware's use of TLS (without Decryption)", July 2016,
<https://arxiv.org/abs/1607.01639>.
[RFC7030] Pritikin, M., Ed., Yee, P., Ed., and D. Harkins, Ed.,
"Enrollment over Secure Transport", RFC 7030,
DOI 10.17487/RFC7030, October 2013,
<https://www.rfc-editor.org/info/rfc7030>.
[RFC7478] Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real-
Time Communication Use Cases and Requirements", RFC 7478,
DOI 10.17487/RFC7478, March 2015,
<https://www.rfc-editor.org/info/rfc7478>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/info/rfc7951>.
[RFC8445] Keranen, A., Holmberg, C., and J. Rosenberg, "Interactive
Connectivity Establishment (ICE): A Protocol for Network
Address Translator (NAT) Traversal", RFC 8445,
DOI 10.17487/RFC8445, July 2018,
<https://www.rfc-editor.org/info/rfc8445>.
[RFC8520] Lear, E., Droms, R., and D. Romascanu, "Manufacturer Usage
Description Specification", RFC 8520,
DOI 10.17487/RFC8520, March 2019,
<https://www.rfc-editor.org/info/rfc8520>.
Authors' Addresses
Tirumaleswar Reddy
McAfee, Inc.
Embassy Golf Link Business Park
Bangalore, Karnataka 560071
India
Email: kondtir@gmail.com
Dan Wing
Citrix Systems, Inc.
4988 Great America Pkwy
Santa Clara, CA 95054
USA
Email: danwing@gmail.com
Reddy & Wing Expires February 7, 2020 [Page 16]