Manufacturer Usage Description SpecificationCisco SystemsRichtistrasse 7WallisellenCH-8304Switzerland+41 44 878 9200lear@cisco.com+1 978 376 3731rdroms@gmail.com+972 54 5555347dromasca@gmail.comInternet-DraftThis memo specifies a component-based architecture for manufacturer
usage descriptions (MUD). The goal of MUD is to provide a means for
Things to signal to the network what sort of access and network
functionality they require to properly function. The initial focus is
on access control. Later work can delve into other aspects.This memo specifies two YANG modules, IPv4 and IPv6 DHCP options, an
LLDP TLV, a URL suffix specification, an X.509 certificate extension
and a means to sign and verify the descriptions.The Internet has largely been constructed for general purpose
computers, those devices that may be used for a purpose that is
specified by those who own the device. presumed that an
end device would be most capable of protecting itself. This made
sense when the typical device was a workstation or a mainframe, and it
continues to make sense for general purpose computing devices today,
including laptops, smart phones, and tablets. discusses design patterns for, and poses questions about,
smart objects. Let us then posit a group of objects that are
specifically not general purpose computers. These devices, which this
memo refers to as Things, have a specific purpose. By definition,
therefore, all other uses are not intended. The combination of these
two statements can be restated as a manufacturer usage description
(MUD) that can be applied at various points within a network.We use the notion of “manufacturer” loosely in this context to refer
to the entity or organization that will state how a device is intended
to be used. For example, in the context of a lightbulb, this might
indeed be the lightbulb manufacturer. In the context of a smarter
device that has a built in Linux stack, it might be an integrator of
that device. The key points are that the device itself is assumed to
serve a limited purpose, and that there may exist an organization in
the supply chain of that device that will take responsibility for
informing the network about that purpose.The intent of MUD is to provide the following:Substantially reduce the threat surface on a device entering a
network to those communications intended by the manufacturer.Provide a means to scale network policies to the ever-increasing
number of types of devices in the network.Provide a means to address at least some vulnerabilities in a way
that is faster than the time it might take to update systems. This will be
particularly true for systems that are no longer supported by their
manufacturer.Keep the cost of implementation of such a system to the bare minimum.Provide a means of extensibility for manufacturers to express other
device capabilities or requirements.MUD consists of three architectural building blocks:A URL that is can be used to locate a description;The description itself, including how it is interpreted, and;A means for local network management systems to retrieve the description.In this specification we describe each of these building blocks and how
they are intended to be used together. However, they may also be used
separately, independent of this specification, by local deployments
for their own purposes.MUD is not intended to address network authorization of general
purpose computers, as their manufacturers cannot envision a specific
communication pattern to describe. In addition, even those devices
that have a single or small number of uses might have very broad
communication patterns. MUD on its own is not for them either.Although MUD can provide network administrators with some additional
protection when device vulnerabilities exist, it will never replace the
need for manufacturers to patch vulnerabilities.Finally, no matter what the manufacturer specifies in a MUD file,
these are not directives, but suggestions. How they are instantiated
locally will depend on many factors and will be ultimately up to the
local network administrator, who must decide what is appropriate in
a given circumstances.A light bulb is intended to light a room. It may be remotely
controlled through the network, and it may make use of a rendezvous
service of some form that an application on a smart phone. What we can
say about that light bulb, then, is that all other network access is
unwanted. It will not contact a news service, nor speak to the
refrigerator, and it has no need of a printer or other devices. It
has no social networking friends. Therefore, an access list applied
to it that states that it will only connect to the single rendezvous
service will not impede the light bulb in performing its function,
while at the same time allowing the network to provide both it and
other devices an additional layer of protection.
manufacturer usage description.
a file containing YANG-based JSON that describes a Thing and associated suggested specific network behavior.
a web server that hosts a MUD file.
the system that requests and receives the MUD file from the MUD
server. After it has processed a MUD file, it may direct changes to
relevant network elements.
a URL that can be used by the MUD controller to receive the MUD file.
the device emitting a MUD URL.
the entity that configures the Thing to emit the MUD URL and the one
who asserts a recommendation in a MUD file. The manufacturer
might not always be the entity that constructs a Thing. It could,
for instance, be a systems integrator, or even a component provider.The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”, “SHALL
NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and
“OPTIONAL” in this document are to be interpreted as described in
.The notion of intended use is in itself not new. Network
administrators apply access lists every day to allow for only such
use. This notion of white listing was well described by Chapman and
Zwicky in . Profiling systems that make use of heuristics
to identify types of systems have existed for years as well.A Thing could just as easily tell the network what sort of access
it requires without going into what sort of system it is. This would,
in effect, be the converse of . In seeking a general
purpose solution, however, we assume that a device has so few
capabilities that it will implement the least necessary capabilities
to function properly. This is a basic economic constraint. Unless
the network would refuse access to such a device, its developers would
have no reason to provide the network any information. To date, such an
assertion has held true.Our work begins with the device emitting a Universal
Resource Locator (URL) . This URL serves both to
classify the device type and to provide a means to locate a policy
file.MUD URLs MUST use the HTTPS scheme .In this memo three means are defined to emit the MUD URL, as follows:A DHCP option, that the DHCP client uses to inform
the DHCP server. The DHCP server may take further actions, such as
retrieve the URL or otherwise pass it along to network management
system or controller.An X.509 constraint. The IEEE has developed that
provides a certificate-based approach to communicate device characteristics,
which itself relies on . The MUD URL extension is
non-critical, as required by IEEE 802.1AR. Various means may be used
to communicate that certificate, including Tunnel Extensible
Authentication Protocol (TEAP) .Finally, a Link Layer Discovery Protocol (LLDP) frame is defined .It is possible that there may be other means for a MUD URL to be
learned by a network. For instance, some devices may already be
fielded or have very limited ability to communicate a MUD URL, and yet
can be identified through some means, such as a serial number or a
public key. In these cases, manufacturers may be able to map those
identifiers to particular MUD URLs (or even the files themselves).
Similarly, there may be alternative resolution mechanisms available
for situations where Internet connectivity is limited or does not
exist. Such mechanisms are not described in this memo, but are
possible. Implementors should allow for this sort of flexibility of
how MUD URLs may be learned.MUD controllers that are able to do so SHOULD retrieve MUD URLs and
signature files as per , using the GET method .
They MUST validate the certificate using the rules in ,
Section 3.1.Requests for MUD URLs SHOULD include an “Accept” header (,
Section 5.3.2) containing “application/mud+json”, an “Accept-Language”
header (, Section 5.3.5), and a “User-Agent” header
(, Section 5.5.3).MUD controllers SHOULD automatically process 3xx response status codes.If a MUD controller is not able to fetch a MUD URL, other means MAY
be used to import MUD files and associated signature files. So long
as the signature of the file can be validated, the file can be used.
In such environments, controllers SHOULD warn administrators when
cache-validity expiry is approaching so that they may check for new
files.When the MUD URL is resolved, the MUD controller retrieves a file that
describes what sort of communications a device is designed to have.
The manufacturer may specify either specific hosts for cloud based
services or certain classes for access within an operational network.
An example of a class might be “devices of a specified manufacturer
type”, where the manufacturer type itself is indicated simply by the
authority component (e.g, the domain name) of the MUD URL. Another
example might be to allow or disallow local access. Just like other
policies, these may be combined. For example:Allow access to devices of the same manufacturerAllow access to and from controllers via Constrained Application
Protocol (COAP)Allow access to local DNS/NTPDeny all other accessA printer might have a description that states:Allow access for port IPP or port LPDAllow local access for port HTTPDeny all other accessIn this way anyone can print to the printer, but local access would
be required for the management interface.The files that are retrieved are intended to be closely aligned to
existing network architectures so that they are easy to deploy. We
make use of YANG because of the time and effort spent to
develop accurate and adequate models for use by network devices. JSON
is used as a serialization for compactness and readability, relative
to XML. Other formats may be chosen with later versions of MUD.While the policy examples given here focus on access control, this is
not intended to be the sole focus. By structuring the model described
in this document with clear extension points, other
descriptions could be included. One that often comes to mind is
quality of service.The YANG modules specified here are extensions of
. The extensions to this model allow for
a manufacturer to express classes of systems that a manufacturer would
find necessary for the proper function of the device. Two modules are
specified. The first module specifies a means for domain names to be
used in ACLs so that devices that have their controllers in the cloud
may be appropriately authorized with domain names, where the mapping
of those names to addresses may rapidly change.The other module abstracts away IP addresses into certain classes that
are instantiated into actual IP addresses through local processing.
Through these classes, manufacturers can specify how the device is
designed to communicate, so that network elements can be configured by
local systems that have local topological knowledge. That is, the
deployment populates the classes that the manufacturer specifies. The
abstractions below map to zero or more hosts, as follows:
A device made by a particular manufacturer, as identified by the authority
component of its MUD URL
Devices that have the same authority component of their MUD URL.
Devices that the local network administrator admits to the particular class.
Devices associated with the MUD URL of a device that the administrator admits.
The class of IP addresses that are scoped within some administrative boundary.
By default it is suggested that this be the local subnet.The “manufacturer” classes can be easily specified by the
manufacturer, whereas controller classes are initially envisioned to
be specified by the administrator.Because manufacturers do not know who will be using their devices, it
is important for functionality referenced in usage descriptions to be
relatively ubiquitous and mature. For these reasons only a limited
subset YANG-based configuration is permitted in a MUD file.With these components laid out we now have the basis for an
architecture. This leads us to ASCII art.In the above diagram, the switch or router collects MUD URLs and
forwards them to the MUD controller (a network management system) for
processing. This happens in different ways, depending on how the URL
is communicated. For instance, in the case of DHCP, the DHCP server
might receive the URL and then process it. In the case of IEEE
802.1X, the switch would carry the URL via a certificate to the
authentication server via EAP over Radius, which would then
process it. One method to do this is TEAP, described in .
The certificate extension is described below.The information returned by the MUD file server (a web server) is
valid for the duration of the Thing’s connection, or as specified in
the description. Thus if the Thing is disconnected, any associated
configuration in the switch can be removed. Similarly, from time to
time the description may be refreshed, based on new capabilities or
communication patterns or vulnerabilities.The web server is typically run by or on behalf of the manufacturer.
Its domain name is that of the authority found in the MUD URL. For
legacy cases where Things cannot emit a URL, if the switch is able to
determine the appropriate URL, it may proxy it, the trivial cases
being a hardcoded MUD-URL on a switch port, or a mapping from some
available identifier such as an L2 address or certificate hash to a
MUD-URL.The role of the MUD controller in this environment is to do the
following:receive MUD URLs,fetch MUD files,translate abstractions in the MUD files to specific network element
configuration,maintain and update any required mappings of the abstractions, andupdate network elements with appropriate configuration.A MUD controller may be a component of a AAA or network management
system. Communication within those systems and from those systems to
network elements is beyond the scope of this memo.As mentioned above, MUD contains architectural building blocks, and so
order of operation may vary. However, here is one clear intended
example:Thing emits URL.That URL is forwarded to a MUD controller by the nearest switch
(how this happens depends on the way in which the MUD URL is emitted).The MUD controller retrieves the MUD file and signature from the MUD file
server, assuming it doesn’t already have copies. After validating
the signature, it may test the
URL against a web or domain reputation service, and it may test any hosts within
the file against those reputation services, as it deems fit.The MUD controller may query the administrator for permission to
add the Thing and associated policy. If the Thing is known or
the Thing type is known, it may skip this step.The MUD controller instantiates local configuration based on
the abstractions defined in this document.The MUD controller configures the switch nearest the Thing.
Other systems may be configured as well.When the Thing disconnects, policy is removed.A MUD file consists of a YANG model that has been serialized in JSON
. For purposes of MUD, the nodes that can be modified are
access lists as augmented by this model. The MUD file is limited to
the serialization of only the following YANG schema:ietf-access-control-list ietf-mud (this document)ietf-acldns (this document)Extensions may be used to add additional schema. This is described
further on.To provide the widest possible deployment, publishers of MUD files
SHOULD make use of the abstractions in this memo and avoid the use of
IP addresses. A MUD controller SHOULD NOT automatically implement any
MUD file that contains IP addresses, especially those that might have
local significance. The addressing of one side of an access list is
implicit, based on whether it is applied as to-device-policy or
from-device-policy.With the exceptions of “name” of the ACL, “type”, “name” of the ACE, and TCP
and UDP source and destination port information, publishers of MUD
files SHOULD limit the use of ACL model leaf nodes expressed to those
found in this specification. Absent any extensions, MUD files are
assumed to implement only the following ACL model features:match-on-ipv4, match-on-ipv6, match-on-tcp,
match-on-udp, match-on-icmpFurthermore, only “accept” or “drop” actions SHOULD be included. A
MUD controller MAY choose to interpret “reject” as “drop”. A MUD
controller SHOULD ignore all other actions. This is because
manufacturers do not have sufficient context within a local deployment
to know whether reject is appropriate. That is a decision that should
be left to a network administrator.Given that MUD does not deal with interfaces, the support of the
“ietf-interfaces” module is not required. Specifically,
the support of interface-related features and branches (e.g.,
interface-attachment and interface-stats) of the ACL YANG module is
not required.In fact, MUD controllers MAY ignore any particular component of a
description or MAY ignore the description in its entirety, and SHOULD
carefully inspect all MUD descriptions. Publishers of MUD files MUST
NOT include other nodes except as described in . See
that section for more information.This module is structured into three parts:The first container “mud” holds information that is relevant
to retrieval and validity of the MUD file itself, as well as policy
intended to and from the Thing.The second component augments the matching container of the ACL
model to add several nodes that are relevant to the MUD URL, or
otherwise abstracted for use within a local environment.The third component augments the tcp-acl container of the ACL
model to add the ability to match on the direction of initiation of a
TCP connection.A valid MUD file will contain two root objects, a “mud” container and
an “access-lists” container. Extensions may add additional root
objects as required. As a reminder, when parsing access-lists,
elements within a “match” block are logically ANDed. In general, a
single abstraction in a match statement should be used. For instance,
it makes little sense to match both “my-controller” and “controller”
with an argument, since they are highly unlikely to be the same value.A simplified graphical representation of the data models is used in
this document. The meaning of the symbols in these diagrams is
explained in .Note that in this section, when we use the term “match” we are
referring to the ACL model “matches” node.The following nodes are defined.This node specifies the integer version of the MUD specification. This memo
specifies version 1. describes access-lists. In the case of
MUD, a MUD file must be explicit in describing the communication
pattern of a Thing, and that includes indicating what is to be
permitted or denied in either direction of communication. Hence each
of these containers indicates the appropriate direction of a flow in
association with a particular Thing. They contain references to
specific access-lists.This is a date-and-time value of when the MUD file was
generated. This is akin to a version number. Its form is taken from
which, for those keeping score, in turn was taken from
Section 5.6 of , which was taken from .This uint8 is the period of time in hours that a network management
station MUST wait since its last retrieval before checking for an
update. It is RECOMMENDED that this value be no less than 24 and MUST
NOT be more than 168 for any Thing that is supported. This period
SHOULD be no shorter than any period determined through HTTP caching
directives (e.g., “cache-control” or “Expires”). N.B., expiring of
this timer does not require the MUD controller to discard the MUD
file, nor terminate access to a Thing. See for more
information.This boolean is an indication from the manufacturer to the network
administrator as to whether or not the Thing is supported. In this
context a Thing is said to not be supported if the manufacturer intends
never to issue an update to the Thing or never update the
MUD file. A MUD controller MAY still periodically check for updates.This is a textual UTF-8 description of the Thing
to be connected. The intent is for administrators to be able to see a
localized name associated with the Thing. It SHOULD NOT exceed 60
characters worth of display space (that is- what the administrator
actually sees).These optional fields are filled in as specified by
. Note that firmware-rev and software-rev
MUST NOT be populated in a MUD file if the device can be upgraded but
the MUD-URL cannot be. This would be the case, for instance, with
MUR-URLs that are contained in 802.1AR certificates.This optional leaf-list names MUD extensions that are used in the MUD
file. Note that NO MUD extensions may be used in a MUD file without
the extensions being declared. Implementations MUST ignore any node
in this file that they do not understand.Note that extensions can either extend the MUD file as described in
the previous paragraph, or they might reference other work. An
extension example can be found in .This node consists of a hostname that would be matched against the
authority component of another Thing’s MUD URL. In its simplest form
“manufacturer” and “same-manufacturer” may be implemented as
access-lists. In more complex forms, additional network capabilities
may be used. For example, if one saw the line
“manufacturer” : “flobbidy.example.com”, then all Things that
registered with a MUD URL that contained flobbity.example.com in its
authority section would match.This null-valued node is an equivalent for when the manufacturer
element is used to indicate the authority that is found in another
Thing’s MUD URL matches that of the authority found in this Thing’s
MUD URL. For example, if the Thing’s MUD URL were
https://b1.example.com/ThingV1, then all devices
that had MUD URL with an authority section of b1.example.com would
match.This string matches the entire MUD URL, thus covering the model that
is unique within the context of the authority. It may contain not
only model information, but versioning information as well, and any
other information that the manufacturer wishes to add. The intended
use is for devices of this precise class to match, to permit or
deny communication between one another.This null-valued node expands to include local networks. Its
default expansion is that packets must not traverse toward a default
route that is received from the router. However, administrators may
expand the expression as is appropriate in their deployments.This URI specifies a value that a controller will register with the
MUD controller. The node then is expanded to the set
of hosts that are so registered. This node may also be a URN. In
this case, the URN describes a well known service, such as DNS or NTP.Great care should be used when invoking the controller class. For one
thing, it requires some understanding by the administrator as to when
it is appropriate. Classes that are standardized may make it possible
to easily name devices that support standard functions. For instance,
the MUD controller could have some knowledge of which DNS servers
should be used for any particular group of Things. Non-standard
classes will likely require some sort of administrator interaction.
Pre-registration in such classes by controllers with the MUD server is
encouraged. The mechanism to do that is beyond the scope of this
work.Controller URIs MAY take the form of a URL (e.g. “http[s]://”).
However, MUD controllers MUST NOT resolve and retrieve such files, and
it is RECOMMENDED that there be no such file at this time, as their
form and function may be defined at a point in the future. For now,
URLs should serve simply as class names and may be populated by the
local deployment administrator.This null-valued node signals to the MUD controller to use whatever
mapping it has for this MUD URL to a particular group of hosts. This may
require prompting the administrator for class members. Future work
should seek to automate membership management.When applied this matches packets when the flow was initiated in the
corresponding direction. specifies IPv6 guidance best
practices. While that document is scoped specifically to IPv6, its
contents are applicable for IPv4 as well. When this flag is set, and
the system has no reason to believe a flow has been initiated it MUST
drop the packet. This node may be implemented in its simplest
form by looking at naked SYN bits, but may also be implemented through
more stateful mechanisms.To keep things relatively simple in addition to whatever definitions
exist, we also apply two additional default behaviors:Anything not explicitly permitted is denied.Local DNS and NTP are, by default, permitted to and from the
Thing.An explicit description of the defaults can be found in .
These are applied AFTER all other explicit rules. Thus, a default
behavior can be changed with a “drop” action.MUD URLs are required to use the HTTPS scheme, in order to establish the
MUD file server’s identity and assure integrity of the MUD file.Any “https://” URL without a query component can be a MUD URL. For example:=======
The MUD URL identifies a Thing with a specificity according to the
manufacturer’s wishes. It could include a brand name, model number, or
something more specific. It also could provide a means to indicate what version
the product is.Specifically, if the intended communication patterns of a Thing change,
as compared to other things, the MUD URL should change. For example, if a
new model of light bulb is released that requires access to different network
services, it would have a separate MUD URL from those that do not.The query string of the MUD URL is reserved for potential future use; MUD URLs
MUST NOT contain queries when sent to the controller. MUD file servers MUST
ignore query parameters that they do not understand.Note that if the MUD URL contains a fragment identifier (e.g., “#foo”), that
information will not be sent to the MUD file server in the HTTP request.
However, it will still be considered a separate MUD URL by the controller.This module specifies an extension to IETF-ACL model such that domain
names may be referenced by augmenting the “matches” node.
Different implementations may deploy differing methods to maintain the
mapping between IP address and domain name, if indeed any are needed.
However, the intent is that resources that are referred to using a
name should be authorized (or not) within an access list.The structure of the change is as follows:The choice of these particular points in the access-list model is
based on the assumption that we are in some way referring to
IP-related resources, as that is what the DNS returns. A domain name
in our context is defined in . The augmentations are
replicated across IPv4 and IPv6 to allow MUD file authors the ability
to control the IP version that the Thing may utilize.The following node are defined.The argument corresponds to a domain name of a source as specified by
inet:host. A number of means may be used to resolve hosts. What is
important is that such resolutions be consistent with ACLs required by
Things to properly operate.The argument corresponds to a domain name of a destination as
specified by inet:host See the previous section relating to
resolution.Note when using either of these with a MUD file, because access is
associated with a particular Thing, MUD files MUST not contain either
a src-dnsname in an ACL associated with from-device-policy or
a dst-dnsname associated with to-device-policy.This example contains two access lists that are intended to provide
outbound access to a cloud service on TCP port 443.In this example, two policies are declared, one from the Thing and
the other to the Thing. Each policy names an access list that
applies to the Thing, and one that applies from. Within each access
list, access is permitted to packets flowing to or from the Thing
that can be mapped to the domain name of “service.bms.example.com”.
For each access list, the enforcement point should expect that the
Thing initiated the connection.The IPv4 MUD URL client option has the following format:Code OPTION_MUD_URL_V4 (161) is assigned by IANA. len is a single
octet that indicates the length of the URL in octets. MUD URL is a
URL. MUD URLs MUST NOT exceed 255 octets.The IPv6 MUD URL client option has the following format:OPTION_MUD_URL_V6 (112; assigned by IANA).option-length contains the length of the URL in octets.The intent of this option is to provide both a new Thing classifier
to the network as well as some recommended configuration to the
routers that implement policy. However, it is entirely the purview of
the network system as managed by the network administrator to decide
what to do with this information. The key function of this option is
simply to identify the type of Thing to the network in a structured
way such that the policy can be easily found with existing toolsets.A DHCPv4 client MAY emit a DHCPv4 option and a DHCPv6 client MAY emit
DHCPv6 option. These options are singletons, as specified in
. Because clients are intended to have at most one MUD URL
associated with them, they may emit at most one MUD URL option via
DHCPv4 and one MUD URL option via DHCPv6. In the case where both v4
and v6 DHCP options are emitted, the same URL MUST be used.Clients SHOULD log or otherwise report improper acknowledgments from
servers, but they MUST NOT modify their MUD URL configuration based on
a server’s response. The server’s response is only an acknowledgment
that the server has processed the option, and promises no specific
network behavior to the client. In particular, it may not be possible
for the server to retrieve the file associated with the MUD URL,
or the local network administration may not wish to use the usage
description. Neither of these situations should be considered in any
way exceptional.A DHCP server may ignore these options or take action based on receipt
of these options. If a server successfully parses the option and the
URL, it MUST return the option with length field set to zero and a
corresponding null URL field as an acknowledgment. Even in this
circumstance, no specific network behavior is guaranteed. When a
server consumes this option, it will either forward the URL and
relevant client information (such as the gateway address or giaddr) to
a network management system, or it will retrieve the usage description
itself by resolving the URL.DHCP servers may implement MUD functionality themselves or they may
pass along appropriate information to a network management system or
MUD controller. A DHCP server that does process the MUD URL MUST adhere
to the process specified in and to validate
the TLS certificate of the web server hosting the MUD file. Those
servers will retrieve the file, process it, create and install the
necessary configuration on the relevant network element. Servers
SHOULD monitor the gateway for state changes on a given interface. A
DHCP server that does not provide MUD functionality and has forwarded
a MUD URL to a MUD controller MUST notify the MUD controller
of any corresponding change to the DHCP state of the client
(such as expiration or explicit release of a network address lease).There are no additional requirements for relays.This section defines an X.509 non-critical certificate extension that
contains a single Uniform Resource Locator (URL) that points to an
on-line Manufacturer Usage Description concerning the certificate
subject. URI must be represented as described in Section 7.4 of .Any Internationalized Resource Identifiers (IRIs) MUST be mapped to
URIs as specified in Section 3.1 of before they are placed
in the certificate extension.The semantics of the URL are defined of this document.The choice of id-pe is based on guidance found in Section 4.2.2 of
:The MUD URL is precisely that: online information about the particular subject.The new extension is identified as follows:While this extension can appear in either an 802.AR manufacturer
certificate (IDevID) or deployment certificate (LDevID), of course it
is not guaranteed in either, nor is it guaranteed to be carried over.
It is RECOMMENDED that MUD controller implementations maintain a table
that maps a Thing to its MUD URL based on IDevIDs.The IEEE802.1AB Link Layer Discovery Protocol (LLDP) is a
one hop vendor-neutral link layer protocol used by end hosts network
Things for advertising their identity, capabilities, and neighbors on
an IEEE 802 local area network. Its Type-Length-Value (TLV) design
allows for ‘vendor-specific’ extensions to be defined. IANA has a
registered IEEE 802 organizationally unique identifier (OUI) defined
as documented in . The MUD LLDP extension uses a subtype
defined in this document to carry the MUD URL.The LLDP vendor specific frame has the following format:where:TLV Type = 127 indicates a vendor-specific TLVlen – indicates the TLV string lengthOUI = 00 00 5E is the organizationally unique identifier of IANAsubtype = 1 (to be assigned by IANA for the MUD URL)MUD URL – the length MUST NOT exceed 255 octetsThe intent of this extension is to provide both a new Thing
classifier to the network as well as some recommended configuration to
the routers that implement policy. However, it is entirely the
purview of the network system as managed by the network administrator
to decide what to do with this information. The key function of this
extension is simply to identify the type of Thing to the network in a
structured way such that the policy can be easily found with existing
toolsets.Hosts, routers, or other network elements that implement this option
are intended to have at most one MUD URL associated with them, so they
may transmit at most one MUD URL value.Hosts, routers, or other network elements that implement this option may
ignore these options or take action based on receipt of these options.
For example they may fill in information in the respective extensions
of the LLDP Management Information Base (LLDP MIB). LLDP operates in a
one-way direction. LLDPDUs are not exchanged as information requests
by one Thing and response sent by another Thing. The other Things do
not acknowledge LLDP information received from a Thing. No specific
network behavior is guaranteed. When a Thing consumes this extension,
it may either forward the URL and relevant remote Thing information to
a MUD controller, or it will retrieve the usage description by
resolving the URL in accordance with normal HTTP semantics.Because MUD files contain information that may be used to configure
network access lists, they are sensitive. To insure that they have
not been tampered with, it is important that they be signed. We make
use of DER-encoded Cryptographic Message Syntax (CMS) for
this purpose.A MUD file MUST be signed using CMS as an opaque binary object. In
order to make successful verification more likely, intermediate
certificates SHOULD be included. The signature is stored at the
location specified in the MUD file. Signatures are
transferred using content-type “application/pkcs7-signature”.For example:Note: A MUD file may need to be re-signed if the signature expires.Prior to retrieving a MUD file the MUD controller SHOULD retrieve the
MUD signature file by retrieving the value of “mud-signature” and
validating the signature across the MUD file.Upon retrieving a MUD file, a MUD controller MUST validate the
signature of the file before continuing with further processing. A
MUD controller MUST cease processing of that file it cannot validate
the chain of trust to a known trust anchor until an administrator has
given approval.The purpose of the signature on the file is to assign accountability
to an entity, whose reputation can be used to guide administrators on
whether or not to accept a given MUD file. It is already common place
to check web reputation on the location of a server on which a file
resides. While it is likely that the manufacturer will be the signer
of the file, this is not strictly necessary, and may not be desirable.
For one thing, in some environments, integrators may install their own
certificates. For another, what is more important is the
accountability of the recommendation, and not the cryptographic
relationship between the device and the file.An example:Note the additional step of verifying the common trust root.One of our design goals is to see that MUD files are able to be
understood by as broad a cross-section of systems as is possible.
Coupled with the fact that we have also chosen to leverage existing
mechanisms, we are left with no ability to negotiate extensions and a
limited desire for those extensions in any event. A such, a
two-tier extensibility framework is employed, as follows:At a coarse grain, a protocol version is included in a MUD URL.
This memo specifies MUD version 1. Any and all changes are
entertained when this version is bumped. Transition approaches
between versions would be a matter for discussion in future versions.At a finer grain, only extensions that would not incur additional
risk to the Thing are permitted. Specifically, adding nodes to the
mud container is permitted with the understanding that such additions
will be ignored by unaware implementations. Any such extensions
SHALL be standardized through the IETF process, and MUST be named in
the “extensions” list. MUD controllers MUST ignore YANG nodes they
do not understand and SHOULD create an exception to be resolved by an
administrator, so as to avoid any policy inconsistencies.Because MUD consists of a number of architectural building blocks, it
is possible to assemble different deployment scenarios. One key
aspect is where to place policy enforcement. In order to protect the
Thing from other Things within a local deployment, policy can be
enforced on the nearest switch or access point. In order to limit
unwanted traffic within a network, it may also be advisable to enforce
policy as close to the Internet as possible. In some circumstances,
policy enforcement may not be available at the closest hop. At that
point, the risk of so-called east-west infection is increased to the
number of Things that are able to communicate without protection.A caution about some of the classes: admission of a Thing into the
“manufacturer” and “same-manufacturer” class may have impact on access
of other Things. Put another way, the admission may grow the
access-list on switches connected to other Things, depending on how
access is managed. Some care should be given on managing that
access-list growth. Alternative methods such as additional
network segmentation can be used to keep that growth within reason.Because as of this writing MUD is a new concept, one can expect a
great many devices to not have implemented it. It remains a local
deployment decision as to whether a device that is first connected
should be alloewed broad or limited access. Furthermore, as mentioned
in the introduction, a deployment may choose to ignore a MUD policy in
its entirety, but simply taken into account the MUD URL as a
classifier to be used as part of a local policy decision.Based on how a MUD URL is emitted, a Thing may be able to lie about
what it is, thus gaining additional network access. There are several
means to limit risk in this case. The most obvious is to only believe
Things that make use of certificate-based authentication such as IEEE
802.1AR certificates. When those certificates are not present,
Things claiming to be of a certain manufacturer SHOULD NOT be
included in that manufacturer grouping without additional validation
of some form. This will occur when it makes use of primitives such as
“manufacturer” for the purpose of accessing Things of a particular
type. Similarly, network management systems may be able to
fingerprint the Thing. In such cases, the MUD URL can act as a
classifier that can be proven or disproven. Fingerprinting may have
other advantages as well: when 802.1AR certificates are used, because
they themselves cannot change, fingerprinting offers the opportunity
to add artificats to the MUD URL. The meaning of such artifacts is
left as future work.Network management systems SHOULD NOT accept a usage description for a
Thing with the same MAC address that has indicated a change of
authority without some additional validation (such as review by a
network administrator). New Things that present some form of
unauthenticated MUD URL SHOULD be validated by some external means
when they would be otherwise be given increased network access.It may be possible for a rogue manufacturer to inappropriately
exercise the MUD file parser, in order to exploit a vulnerability.
There are three recommended approaches to address this threat. The
first is to validate the signature of the MUD file. The second is to
have a system do a primary scan of the file to ensure that it is both
parseable and believable at some level. MUD files will likely be
relatively small, to start with. The number of ACEs used by any given
Thing should be relatively small as well. It may also be useful
to limit retrieval of MUD URLs to only those sites that are known to
have decent web or domain reputations.Use of a URL necessitates the use of domain names. If a domain name
changes ownership, the new owner of that domain may be able to provide
MUD files that MUD controllers would consider valid. There are a few
approaches that can mitigate this attack. First, MUD controllers
SHOULD cache certificates used by the MUD file server. When a new
certificate is retrieved for whatever reason, the MUD controller
should check to see if ownership of the domain has changed. A fair
programmatic approximation of this is when the name servers for the
domain have changed. If the actual MUD file has changed, the
controller MAY check the WHOIS database to see if registration
ownership of a domain has changed. If a change has occured, or if for
some reason it is not possible to determine whether ownership has
changed, further review may be warranted. Note, this remediation does
not take into account the case of a Thing that was produced long ago
and only recently fielded, or the case where a new MUD controller has
been installed.It may not be possible for a MUD controller to retrieve a MUD file at
any given time. Should a MUD controller fail to retrieve a MUD file,
it SHOULD consider the existing one safe to use, at least for a time.
After some period, it SHOULD log that it has been unable to retrieve
the file. There may be very good reasons for such failures, including
the possibility that the MUD controller is in an off-line environment,
the local Internet connection has failed, or the remote Internet
connection has failed. It is also possible that an attacker is
attempting to prevent onboarding of a device. It is a local
deployment decision as to whether or not devices may be onboarded in
the face of such failures.The release of a MUD URL by a Thing reveals what the Thing is, and
provides an attacker with guidance on what vulnerabilities may be
present.While the MUD URL itself is not intended to be unique to a specific
Thing, the release of the URL may aid an observer in identifying
individuals when combined with other information. This is a privacy
consideration.In addressing both of these concerns, implementors should take into
account what other information they are advertising through mechanisms
such as mDNS, how a Thing might otherwise be identified,
perhaps through how it behaves when it is connected to the network,
whether a Thing is intended to be used by individuals or carry
personal identifying information, and then apply appropriate data
minimization techniques. One approach is to make use of TEAP
as the means to share information with authorized
components in the network. Network elements may also assist in
limiting access to the MUD URL through the use of mechanisms such as
DHCPv6-Shield .Please note that the security considerations mentioned in Section 4.7
of are not applicable in this case
because the YANG serialization is not intended to be accessed via
NETCONF. However, for those who try to instantiate this model in a
network element via NETCONF, all objects in each model in this draft
exhibit similar security characteristics as
. The basic purpose of MUD is to
configure access, and so by its very nature can be disruptive if used
by unauthorized parties.The following YANG modules are requested to be registred in the “IANA
Module Names” registry:The ietf-mud module:Name: ietf-mudXML Namespace: urn:ietf:params:xml:ns:yang:ietf-mudPrefix: ief-mudReference: This memoThe ietf-acldns module:Name: ietf-acldnsXML Namespace: urn:ietf:params:xml:ns:yang:ietf-acldnsPrefix: ietf-acldnsReference: This memoThe IANA has allocated option 161 in the Dynamic Host Configuration
Protocol (DHCP) and Bootstrap Protocol (BOOTP) Parameters registry for
the MUD DHCPv4 option, and option 112 for DHCPv6, as described in .IANA is kindly requested to make the following assignments for:o The MUDURLExtnModule-2016 ASN.1 module in the “SMI Security for
PKIX Module Identifier” registry (1.3.6.1.5.5.7.0).o id-pe-mud-url object identifier from the “SMI Security for PKIX
Certificate Extension” registry (1.3.6.1.5.5.7.1).The use of these values is specified in .The following media-type is defined for transfer of MUD file:IANA is requested to create a new registry for IANA Link Layer
Discovery Protocol (LLDP) TLV subtype values. The recommended policy
for this registry is Expert Review. The maximum number of entries in
the registry is 256.IANA is required to populate the initial registry with the value:LLDP subtype value = 1
(All the other 255 values should be initially marked as ‘Unassigned’.)Description = the Manufacturer Usage Description (MUD) Uniform Resource Locator (URL)Reference = < this document >The following parameter registry is requested to be added in
accordance with The following entries should be added to the “urn:ietf:params:mud” name space:“urn:ietf:params:mud:dns” refers to the service specified by .
“urn:ietf:params:mud:ntp” refers to the service specified by .The IANA is requested to establish a registry of extensions as follows:Each extension MUST follow the rules specified in this specification.
As is usual, the IANA issues early allocations based in accordance
with .The authors would like to thank Einar Nilsen-Nygaard, who
singlehandedly updated the model to match the updated ACL model,
Bernie Volz, Tom Gindin, Brian Weis, Sandeep Kumar, Thorsten Dahm,
John Bashinski, Steve Rich, Jim Bieda, Dan Wing, Joe Clarke, Henk
Birkholz, Adam Montville, and Robert Sparks for their valuable
advice and reviews. Russ Housley entirely rewrote to be a
complete module. Adrian Farrel provided the basis for privacy
considerations text. Kent Watsen provided a thorough review of the
architecture and the YANG model. The remaining errors in this work
are entirely the responsibility of the authors.Requirements for Internet Hosts - Application and SupportThis RFC is an official specification for the Internet community. It incorporates by reference, amends, corrects, and supplements the primary protocol standards documents relating to hosts. [STANDARDS-TRACK]Key words for use in RFCs to Indicate Requirement LevelsIn many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.HTTP Over TLSThis memo describes how to use Transport Layer Security (TLS) to secure Hypertext Transfer Protocol (HTTP) connections over the Internet. This memo provides information for the Internet community.Extensible Authentication Protocol (EAP)This document defines the Extensible Authentication Protocol (EAP), an authentication framework which supports multiple authentication methods. EAP typically runs directly over data link layers such as Point-to-Point Protocol (PPP) or IEEE 802, without requiring IP. EAP provides its own support for duplicate elimination and retransmission, but is reliant on lower layer ordering guarantees. Fragmentation is not supported within EAP itself; however, individual EAP methods may support this. This document obsoletes RFC 2284. A summary of the changes between this document and RFC 2284 is available in Appendix A. [STANDARDS-TRACK]Uniform Resource Identifier (URI): Generic SyntaxA Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. This specification defines the generic URI syntax and a process for resolving URI references that might be in relative form, along with guidelines and security considerations for the use of URIs on the Internet. The URI syntax defines a grammar that is a superset of all valid URIs, allowing an implementation to parse the common components of a URI reference without knowing the scheme-specific requirements of every possible identifier. This specification does not define a generative grammar for URIs; that task is performed by the individual specifications of each URI scheme. [STANDARDS-TRACK]Internationalized Resource Identifiers (IRIs)This document defines a new protocol element, the Internationalized Resource Identifier (IRI), as a complement of the Uniform Resource Identifier (URI). An IRI is a sequence of characters from the Universal Character Set (Unicode/ISO 10646). A mapping from IRIs to URIs is defined, which means that IRIs can be used instead of URIs, where appropriate, to identify resources. The approach of defining a new protocol element was chosen instead of extending or changing the definition of URIs. This was done in order to allow a clear distinction and to avoid incompatibilities with existing software. Guidelines are provided for the use and deployment of IRIs in various protocols, formats, and software components that currently deal with URIs.Network Access Control List (ACL) YANG Data ModelThis document describes a data model of Access Control List (ACL) basic building blocks. Editorial Note (To be removed by RFC Editor) This draft contains many placeholder values that need to be replaced with finalized values at the time of publication. This note summarizes all of the substitutions that are needed. Please note that no other RFC Editor instructions are specified anywhere else in this document. Artwork in this document contains shorthand references to drafts in progress. Please apply the following replacements o "XXXX" --> the assigned RFC value for this draft both in this draft and in the YANG models under the revision statement. o Revision date in model needs to get updated with the date the draft gets approved. The date also needs to get reflected on the line with <CODE BEGINS>.YANG Tree DiagramsThis document captures the current syntax used in YANG module Tree Diagrams. The purpose of this document is to provide a single location for this definition. This syntax may be updated from time to time based on the evolution of the YANG language.A YANG Data Model for Hardware ManagementThis document defines a YANG data model for the management of hardware on a single server.Network Time Protocol Version 4: Protocol and Algorithms SpecificationThe Network Time Protocol (NTP) is widely used to synchronize computer clocks in the Internet. This document describes NTP version 4 (NTPv4), which is backwards compatible with NTP version 3 (NTPv3), described in RFC 1305, as well as previous versions of the protocol. NTPv4 includes a modified protocol header to accommodate the Internet Protocol version 6 address family. NTPv4 includes fundamental improvements in the mitigation and discipline algorithms that extend the potential accuracy to the tens of microseconds with modern workstations and fast LANs. It includes a dynamic server discovery scheme, so that in many cases, specific server configuration is not required. It corrects certain errors in the NTPv3 design and implementation and includes an optional extension mechanism. [STANDARDS-TRACK]Common YANG Data TypesThis document introduces a collection of common data types to be used with the YANG data modeling language. This document obsoletes RFC 6021.Dynamic Host Configuration ProtocolThe Dynamic Host Configuration Protocol (DHCP) provides a framework for passing configuration information to hosts on a TCPIP network. DHCP is based on the Bootstrap Protocol (BOOTP), adding the capability of automatic allocation of reusable network addresses and additional configuration options. [STANDARDS-TRACK]Dynamic Host Configuration Protocol for IPv6 (DHCPv6)Guidelines for Creating New DHCPv6 OptionsThis document provides guidance to prospective DHCPv6 option developers to help them create option formats that are easily adoptable by existing DHCPv6 software. It also provides guidelines for expert reviewers to evaluate new registrations. This document updates RFC 3315.DHCPv6-Shield: Protecting against Rogue DHCPv6 ServersThis document specifies a mechanism for protecting hosts connected to a switched network against rogue DHCPv6 servers. It is based on DHCPv6 packet filtering at the layer 2 device at which the packets are received. A similar mechanism has been widely deployed in IPv4 networks ('DHCP snooping'); hence, it is desirable that similar functionality be provided for IPv6 networks. This document specifies a Best Current Practice for the implementation of DHCPv6-Shield.The YANG 1.1 Data Modeling LanguageYANG is a data modeling language used to model configuration data, state data, Remote Procedure Calls, and notifications for network management protocols. This document describes the syntax and semantics of version 1.1 of the YANG language. YANG version 1.1 is a maintenance release of the YANG language, addressing ambiguities and defects in the original specification. There are a small number of backward incompatibilities from YANG version 1. This document also specifies the YANG mappings to the Network Configuration Protocol (NETCONF).Early IANA Allocation of Standards Track Code PointsThis memo describes the process for early allocation of code points by IANA from registries for which "Specification Required", "RFC Required", "IETF Review", or "Standards Action" policies apply. This process can be used to alleviate the problem where code point allocation is needed to facilitate desired or required implementation and deployment experience prior to publication of an RFC, which would normally trigger code point allocation. The procedures in this document are intended to apply only to IETF Stream documents.Internet X.509 Public Key Infrastructure Certificate and Certificate Revocation List (CRL) ProfileThis memo profiles the X.509 v3 certificate and X.509 v2 certificate revocation list (CRL) for use in the Internet. An overview of this approach and model is provided as an introduction. The X.509 v3 certificate format is described in detail, with additional information regarding the format and semantics of Internet name forms. Standard certificate extensions are described and two Internet-specific extensions are defined. A set of required certificate extensions is specified. The X.509 v2 CRL format is described in detail along with standard and Internet-specific extensions. An algorithm for X.509 certification path validation is described. An ASN.1 module and examples are provided in the appendices. [STANDARDS-TRACK]Cryptographic Message Syntax (CMS)This document describes the Cryptographic Message Syntax (CMS). This syntax is used to digitally sign, digest, authenticate, or encrypt arbitrary message content. [STANDARDS-TRACK]Internet Assigned Numbers Authority (IANA) Procedures for the Management of the Service Name and Transport Protocol Port Number RegistryThis document defines the procedures that the Internet Assigned Numbers Authority (IANA) uses when handling assignment and other requests related to the Service Name and Transport Protocol Port Number registry. It also discusses the rationale and principles behind these procedures and how they facilitate the long-term sustainability of the registry.This document updates IANA's procedures by obsoleting the previous UDP and TCP port assignment procedures defined in Sections 8 and 9.1 of the IANA Allocation Guidelines, and it updates the IANA service name and port assignment procedures for UDP-Lite, the Datagram Congestion Control Protocol (DCCP), and the Stream Control Transmission Protocol (SCTP). It also updates the DNS SRV specification to clarify what a service name is and how it is registered. This memo documents an Internet Best Current Practice.JSON Encoding of Data Modeled with YANGThis document defines encoding rules for representing configuration data, state data, parameters of Remote Procedure Call (RPC) operations or actions, and notifications defined using YANG as JavaScript Object Notation (JSON) text.IEEE Standard for Local and Metropolitan Area Networks-- Station and Media Access Control Connectivity DiscoveryInstitute for Electrical and Electronics EngineersHypertext Transfer Protocol (HTTP/1.1): Message Syntax and RoutingThe Hypertext Transfer Protocol (HTTP) is a stateless application-level protocol for distributed, collaborative, hypertext information systems. This document provides an overview of HTTP architecture and its associated terminology, defines the "http" and "https" Uniform Resource Identifier (URI) schemes, defines the HTTP/1.1 message syntax and parsing requirements, and describes related security concerns for implementations.Hypertext Transfer Protocol (HTTP/1.1): Semantics and ContentThe Hypertext Transfer Protocol (HTTP) is a stateless \%application- level protocol for distributed, collaborative, hypertext information systems. This document defines the semantics of HTTP/1.1 messages, as expressed by request methods, request header fields, response status codes, and response header fields, along with the payload of messages (metadata and body content) and mechanisms for content negotiation.RADIUS Authentication Client MIBThis memo defines a set of extensions which instrument RADIUS authentication client functions. [STANDARDS-TRACK]IAB and IESG Statement on Cryptographic Technology and the InternetIABIESGThe Internet Architecture Board (IAB) and the Internet Engineering Steering Group (IESG), the bodies which oversee architecture and standards for the Internet, are concerned by the need for increased protection of international commercial transactions on the Internet, and by the need to offer all Internet users an adequate degree of privacy. This memo provides information for the Internet community. This memo does not specify an Internet standard of any kind.Date and Time on the Internet: TimestampsAn IETF URN Sub-namespace for Registered Protocol ParametersThis document describes a new sub-delegation for the 'ietf' URN namespace for registered protocol items. The 'ietf' URN namespace is defined in RFC 2648 as a root for persistent URIs that refer to IETF- defined resources. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements.Recommended Simple Security Capabilities in Customer Premises Equipment (CPE) for Providing Residential IPv6 Internet ServiceThis document identifies a set of recommendations for the makers of devices and describes how to provide for "simple security" capabilities at the perimeter of local-area IPv6 networks in Internet-enabled homes and small offices. This document is not an Internet Standards Track specification; it is published for informational purposes.The Common Log Format (CLF) for the Session Initiation Protocol (SIP): Framework and Information ModelWell-known web servers such as Apache and web proxies like Squid support event logging using a common log format. The logs produced using these de facto standard formats are invaluable to system administrators for troubleshooting a server and tool writers to craft tools that mine the log files and produce reports and trends. Furthermore, these log files can also be used to train anomaly detection systems and feed events into a security event management system. The Session Initiation Protocol (SIP) does not have a common log format, and, as a result, each server supports a distinct log format that makes it unnecessarily complex to produce tools to do trend analysis and security detection. This document describes a framework, including requirements and analysis of existing approaches, and specifies an information model for development of a SIP common log file format that can be used uniformly by user agents, proxies, registrars, and redirect servers as well as back-to-back user agents.IANA Considerations and IETF Protocol and Documentation Usage for IEEE 802 ParametersSome IETF protocols make use of Ethernet frame formats and IEEE 802 parameters. This document discusses several uses of such parameters in IETF protocols, specifies IANA considerations for assignment of points under the IANA OUI (Organizationally Unique Identifier), and provides some values for use in documentation. This document obsoletes RFC 5342.Tunnel Extensible Authentication Protocol (TEAP) Version 1This document defines the Tunnel Extensible Authentication Protocol (TEAP) version 1. TEAP is a tunnel-based EAP method that enables secure communication between a peer and a server by using the Transport Layer Security (TLS) protocol to establish a mutually authenticated tunnel. Within the tunnel, TLV objects are used to convey authentication-related data between the EAP peer and the EAP server.Architectural Considerations in Smart Object NetworkingThe term "Internet of Things" (IoT) denotes a trend where a large number of embedded devices employ communication services offered by Internet protocols. Many of these devices, often called "smart objects", are not directly operated by humans but exist as components in buildings or vehicles, or are spread out in the environment. Following the theme "Everything that can be connected will be connected", engineers and researchers designing smart object networks need to decide how to achieve this in practice.This document offers guidance to engineers designing Internet- connected smart objects.Port Control Protocol (PCP) Server SelectionThis document specifies the behavior to be followed by a Port Control Protocol (PCP) client to contact its PCP server(s) when one or several PCP server IP addresses are configured.This document updates RFC 6887.A YANG Data Model for Interface ManagementThis document defines a YANG data model for the management of network interfaces. It is expected that interface-type-specific data models augment the generic interfaces data model defined in this document. The data model includes configuration data and state data (status information and counters for the collection of statistics).The Constrained Application Protocol (CoAP)The Constrained Application Protocol (CoAP) is a specialized web transfer protocol for use with constrained nodes and constrained (e.g., low-power, lossy) networks. The nodes often have 8-bit microcontrollers with small amounts of ROM and RAM, while constrained networks such as IPv6 over Low-Power Wireless Personal Area Networks (6LoWPANs) often have high packet error rates and a typical throughput of 10s of kbit/s. The protocol is designed for machine- to-machine (M2M) applications such as smart energy and building automation.CoAP provides a request/response interaction model between application endpoints, supports built-in discovery of services and resources, and includes key concepts of the Web such as URIs and Internet media types. CoAP is designed to easily interface with HTTP for integration with the Web while meeting specialized requirements such as multicast support, very low overhead, and simplicity for constrained environments.Data elements and interchange formats - Information interchange - Representation of dates and timesInternational Organization for StandardizationGuidelines for Authors and Reviewers of YANG Data Model DocumentsThis memo provides guidelines for authors and reviewers of Standards Track specifications containing YANG data model modules. Applicable portions may be used as a basis for reviews of other YANG data model documents. Recommendations and procedures are defined, which are intended to increase interoperability and usability of Network Configuration Protocol (NETCONF) and RESTCONF protocol implementations that utilize YANG data model modules. This document obsoletes RFC 6087.Secure Device IdentityInstitute for Electrical and Electronics EngineersBuilding Internet FirewallsRFC Editor to remove this section prior to publication.Draft -16add mud-signature element based on review commentsredo mud-urlmake clear that systeminfo uses UTF8Draft -13 to -14:Final WGLC comments and review commentsMove version from MUD-URL to ModelHave MUD-URL in modelUpdate based on update to draft-ietf-netmod-acl-modelPoint to tree diagram draft instead of 6087bis.Draft -12 to -13:Additional WGLC commentsDraft -10 to -12:These are based on WGLC comments:Correct examples based on ACL model changes.Change ordering nodes.Additional explanatory text around systeminfo.Change ordering in examples.Make it VERY VERY VERY VERY clear that these are recommendations,
not mandates.DHCP -> NTP in some of the intro text.Remove masa-server“Things” to “network elements” in a few key places.Reference to JSON YANG RFC added.Draft -10 to -11:Example correctionsTypoFix two lists.Addition of ‘any-acl’ and ‘mud-acl’ in the list of allowed features.Clarification of what should be in a MUD file.Draft -09 to -10:AD input.Correct dates.Add compliance sentence as to which ACL module features are implemented.Draft -08 to -09:Resolution of Security Area review, IoT directorate review,
GenART review, YANG doctors review.change of YANG structure to address mandatory nodes.Terminology cleanup.specify out extra portion of MUD-URL.consistency changes.improved YANG descriptions.Remove extra revisions.Track ACL model changes.Additional cautions on use of ACL model; further clarifications
on extensions.Draft -07 to -08:a number of editorials corrected.definition of MUD file tweaked.Draft -06 to -07:Examples updated.Additional clarification for direction-initiated.Additional implementation guidance given.Draft -06 to -07:Update models to match new ACL modelextract directionality from the ACL, introducing a new device container.Draft -05 to -06:Make clear that this is a component architecture (Polk and Watson)Add order of operations (Watson)Add extensions leaf-list (Pritikin)Remove previous-mud-file (Watson)Modify text in last-update (Watson)Clarify local networks (Weis, Watson)Fix contact info (Watson)Terminology clarification (Weis)Advice on how to handle LDevIDs (Watson)Add deployment considerations (Watson)Add some additional text about fingerprinting (Watson)Appropriate references to 6087bis (Watson)Change systeminfo to a URL to be referenced (Lear)Draft -04 to -05:
* syntax error correctionDraft -03 to -04:
* Re-add my-controllerDraft -02 to -03:
* Additional IANA updates
* Format correction in YANG.
* Add reference to TEAP.Draft -01 to -02:
* Update IANA considerations
* Accept Russ Housley rewrite of X.509 text
* Include privacy considerations text
* Redo the URL limit. Still 255 bytes, but now stated in the URL definition.
* Change URI registration to be under urn:ietf:paramsDraft -00 to -01:
* Fix cert trust text.
* change supportInformation to meta-info
* Add an informational element in.
* add urn registry and create first entry
* add default elementsWhat follows is the portion of a MUD file that permits DNS traffic to
a controller that is registered with the URN “urn:ietf:params:mud:dns”
and traffic NTP to a controller that is registered
“urn:ietf:params:mud:ntp”. This is considered the default behavior
and the ACEs are in effect appended to whatever other “ace” entries
that a MUD file contains. To block DNS or NTP one repeats the
matching statement but replaces the “forwarding” action “accept” with
“drop”. Because ACEs are processed in the order they are received,
the defaults would not be reached. A MUD controller might further
decide to optimize to simply not include the defaults when they are
overriden.Four “acl” list entries that implement default MUD nodes are listed
below. Two are for IPv4 and two are for IPv6 (one in each direction
for both versions of IP). Note that neither access-list name nor ace
name need be retained or used in any way by local implementations, but
are simply there for completeness’ sake.In this sample extension we augment the core MUD model to indicate
whether the device implements DETNET. If a device later attempts to
make use of DETNET, an notification or exception might be generated.
Note that this example is intended only for illustrative purposes.This extension augments the MUD model to include a single node,
using the following sample module that has the following tree
structure:The model is defined as follows:Using the previous example, we now show how the extension would be
expressed: