Patent Publication Number: US-2021194815-A1

Title: Telemetry collection and policy enforcement using asset tagging

Description:
RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 62/951.645, filed on Dec. 20, 2019, entitled “INTENT-BASED SECURITY FOR INDUSTRIAL IOT DEVICES” by Barton et al., the contents of which are incorporated by reference herein. 
    
    
     TECHNICAL FIELD 
     The present disclosure relates generally to computer networks, and, more particularly, to telemetry collection and policy enforcement using asset tagging. 
     BACKGROUND 
     The Internet of Things, or “IoT” for short, represents an evolution of computer networks that seeks to connect many everyday objects to the Internet. Notably, there has been a recent proliferation of ‘smart’ devices that are Internet-capable such as thermostats, lighting, televisions, cameras, and the like. In many implementations, these devices may also communicate with one another. For example, an IoT motion sensor may communicate with one or more smart lightbulbs, to actuate the lighting in a room when a person enters the room. Vehicles are another class of ‘things’ that are being connected via the IoT for purposes of sharing sensor data, implementing self-driving capabilities, monitoring, and the like. 
     The nature of the IoT makes network security particularly challenging, especially in the case of industrial settings, such as factories, mines, ports, power substations, and the like. Indeed, these types of networks are typically large scale in nature, include a variety of legacy devices that do not support authentication methods (e.g., 802.1x) and lack system patching, making it very difficult to define adequate security policies for each device. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The embodiments herein may be better understood by referring to the following description in conjunction with the accompanying drawings in which like reference numerals indicate identically or functionally similar elements, of which: 
         FIG. 1  illustrate an example network; 
         FIG. 2  illustrates an example network device/node; 
         FIG. 3  illustrates an example network architecture for an industrial network; 
         FIGS. 4A-4B  illustrate example displays of component and activity tags; 
         FIG. 5  illustrates an example display of an asset profile; 
         FIGS. 6A-6C  illustrate examples displays of captured flow information; and 
         FIG. 7  illustrates an example simplified procedure for telemetry collection and policy enforcement using asset tagging. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
     Overview 
     According to one or more embodiments of the disclosure, a networking device in a network receives a policy for an endpoint device in the network. The policy specifies one or more component tags and one or more activity tags that were assigned to the endpoint device based on deep packet inspection of traffic associated with the endpoint device. The networking device identifies a set of tags for a particular traffic flow in the network associated with the endpoint device. The set of tags comprises one or more component tags or activity tags associated with the particular traffic flow. The networking device makes a determination that the particular traffic flow violates the policy based on the set of tags for the particular traffic flow comprising a tag that is not in the policy. The networking device initiates, based on the determination that the particular traffic flow violates the policy, a corrective measure with respect to the particular traffic flow. 
     Description 
     A computer network is a geographically distributed collection of nodes interconnected by communication links and segments for transporting data between end nodes, such as personal computers and workstations, or other devices, such as sensors, etc. Many types of networks are available, ranging from local area networks (LANs) to wide area networks (WANs). LANs typically connect the nodes over dedicated private communications links located in the same general physical location, such as a building or campus. WANs, on the other hand, typically connect geographically dispersed nodes over long-distance communications links, such as common carrier telephone lines, optical lightpaths, synchronous optical networks (SONET), synchronous digital hierarchy (SDH) links, or Powerline Communications, and others. Other types of networks, such as field area networks (FANs), neighborhood area networks (NANs), personal area networks (PANs), etc. may also make up the components of any given computer network. 
     In various embodiments, computer networks may include an Internet of Things network. Loosely, the term “Internet of Things” or “IoT” (or “Internet of Everything” or “IoE”) refers to uniquely identifiable objects (things) and their virtual representations in a network-based architecture. In particular, the IoT involves the ability to connect more than just computers and communications devices, but rather the ability to connect “objects” in general, such as lights, appliances, vehicles, heating, ventilating, and air-conditioning (HVAC), windows and window shades and blinds, doors, locks, etc. The “Internet of Things” thus generally refers to the interconnection of objects (e.g., smart objects), such as sensors and actuators, over a computer network (e.g., via IP), which may be the public Internet or a private network. 
     Often, IoT networks operate within a shared-media mesh networks, such as wireless or Powerline Communication networks, etc., and are often on what is referred to as Low-Power and Lossy Networks (LLNs), which are a class of network in which both the routers and their interconnect are constrained. That is, LLN devices/routers typically operate with constraints, e.g., processing power, memory, and/or energy (battery), and their interconnects are characterized by, illustratively, high loss rates, low data rates, and/or instability. IoT networks are comprised of anything from a few dozen to thousands or even millions of devices, and support point-to-point traffic (between devices inside the network), point-to-multipoint traffic (from a central control point such as a root node to a subset of devices inside the network), and multipoint-to-point traffic (from devices inside the network towards a central control point). 
     Fog computing is a distributed approach of cloud implementation that acts as an intermediate layer from local networks (e.g., IoT networks) to the cloud (e.g., centralized and/or shared resources, as will be understood by those skilled in the art). That is, generally, fog computing entails using devices at the network edge to provide application services, including computation, networking, and storage, to the local nodes in the network, in contrast to cloud-based approaches that rely on remote data centers/cloud environments for the services. To this end, a fog node is a functional node that is deployed close to fog endpoints to provide computing, storage, and networking resources and services. Multiple fog nodes organized or configured together form a fog system, to implement a particular solution. Fog nodes and fog systems can have the same or complementary capabilities, in various implementations. That is, each individual fog node does not have to implement the entire spectrum of capabilities. Instead, the fog capabilities may be distributed across multiple fog nodes and systems, which may collaborate to help each other to provide the desired services. In other words, a fog system can include any number of virtualized services and/or data stores that are spread across the distributed fog nodes. This may include a master-slave configuration, publish-subscribe configuration, or peer-to-peer configuration. 
     Low power and Lossy Networks (LLNs), e.g., certain sensor networks, may be used in a myriad of applications such as for “Smart Grid” and “Smart Cities.” A number of challenges in LLNs have been presented, such as: 
     1) Links are generally lossy, such that a Packet Delivery Rate/Rat(PDR) can dramatically vary due to various sources of interferences, e.g., considerably affecting the bit error rate (BER); 
     2) Links are generally low bandwidth, such that control plane traffic must generally be bounded and negligible compared to the low rate data traffic; 
     3) There are a number of use cases that require specifying a set of link and node metrics, some of them being dynamic, thus requiring specific smoothing functions to avoid routing instability, considerably draining bandwidth and energy; 
     4) Constraint-routing may be required by some applications, e.g., to establish routing paths that will avoid non-encrypted links, nodes running low on energy, etc.; 
     5) Scale of the networks may become very large, e.g., on the order of several thousands to millions of nodes; and 
     6) Nodes may be constrained with a low memory, a reduced processing capability, a low power supply (e.g., battery). 
     In other words, LLNs are a class of network in which both the routers and their interconnect are constrained: LLN routers typically operate with constraints, e.g., processing power, memory, and/or energy (battery), and their interconnects are characterized by, illustratively, high loss rates, low data rates, and/or instability. LLNs are comprised of anything from a few dozen and up to thousands or even millions of LLN routers, and support point-to-point traffic (between devices inside the LLN), point-to-multipoint traffic (from a central control point to a subset of devices inside the LLN) and multipoint-to-point traffic (from devices inside the LLN towards a central control point). 
     An example implementation of LLNs is an “Internet of Things” network. Loosely, the term “Internet of Things” or “IoT” may be used by those in the art to refer to uniquely identifiable objects (things) and their virtual representations in a network-based architecture. In particular, the next frontier in the evolution of the Internet is the ability to connect more than just computers and communications devices, but rather the ability to connect “objects” in general, such as lights, appliances, vehicles, HVAC (heating, ventilating, and air-conditioning), windows and window shades and blinds, doors, locks, etc. The “Internet of Things” thus generally refers to the interconnection of objects (e.g., smart objects), such as sensors and actuators, over a computer network (e.g., IP), which may be the Public Internet or a private network. Such devices have been used in the industry for decades, usually in the form of non-IP or proprietary protocols that are connected to IP networks by way of protocol translation gateways. With the emergence of a myriad of applications, such as the smart grid advanced metering infrastructure (AMI), smart cities, and building and industrial automation, and cars (e.g., that can interconnect millions of objects for sensing things like power quality, tire pressure, and temperature and that can actuate engines and lights), it has been of the utmost importance to extend the IP protocol suite for these networks. 
       FIG. 1  is a schematic block diagram of an example simplified computer network  100  illustratively comprising nodes/devices at various levels of the network, interconnected by various methods of communication. For instance, the links may be wired links or shared media (e.g., wireless links, powerline communication links, etc.) where certain nodes, such as, e.g., routers, sensors, computers, etc., may be in communication with other devices, e.g., based on connectivity, distance, signal strength, current operational status, location, etc. 
     Specifically, as shown in the example IoT network  100 , three illustrative layers are shown, namely cloud layer  110 , fog layer  120 , and IoT device layer  130 . Illustratively, the cloud  110  may comprise general connectivity via the Internet  112 , and may contain one or more datacenters  114  with one or more centralized servers  116  or other devices, as will be appreciated by those skilled in the art. Within the fog layer  120 , various fog nodes/devices  122  (e.g., with fog modules, described below) may execute various fog computing resources on network edge devices, as opposed to datacenter/cloud-based servers or on the endpoint nodes  132  themselves of the IoT layer  130 . For example, fog nodes/devices  122  may include edge routers and/or other networking devices that provide connectivity between cloud layer  110  and IoT device layer  130 . Data packets (e.g., traffic and/or messages sent between the devices/nodes) may be exchanged among the nodes/devices of the computer network  100  using predefined network communication protocols such as certain known wired protocols, wireless protocols, powerline communication protocols, or other shared-media protocols where appropriate. In this context, a protocol consists of a set of rules defining how the nodes interact with each other. 
     Those skilled in the art will understand that any number of nodes, devices, links, etc. may be used in the computer network, and that the view shown herein is for simplicity. Also, those skilled in the art will further understand that while the network is shown in a certain orientation, the network  100  is merely an example illustration that is not meant to limit the disclosure. 
     Data packets (e.g., traffic and/or messages) may be exchanged among the nodes/devices of the computer network  100  using predefined network communication protocols such as certain known wired protocols, wireless protocols (e.g., IEEE Std. 802.15.4, Wi-Fi, Bluetooth®, DECT-Ultra Low Energy, LoRa, etc..), powerline communication protocols, or other shared-media protocols where appropriate. In this context, a protocol consists of a set of rules defining how the nodes interact with each other. 
       FIG. 2  is a schematic block diagram of an example node/device  200  that may be used with one or more embodiments described herein, e.g., as any of the nodes or devices shown in  FIG. 1  above or described in further detail below. The device  200  may comprise one or more network interfaces  210  (e.g., wired, wireless, etc.), at least one processor  220 , and a memory  240  interconnected by a system bus  250 , as well as a power supply  260  (e.g., battery, plug-in, etc.). 
     Network interface(s)  210  include the mechanical, electrical, and signaling circuitry for communicating data over links coupled to the network. The network interfaces  210  may be configured to transmit and/or receive data using a variety of different communication protocols, such as TCP/IP, UDP, etc. Note that the device  200  may have multiple different types of network connections  210 , e.g., wireless and wired/physical connections, and that the view herein is merely for illustration. Also, while the network interface  210  is shown separately from power supply  260 , for powerline communications the network interface  210  may communicate through the power supply  260 , or may be an integral component of the power supply. In some specific configurations the powerline communication signal may be coupled to the power line feeding into the power supply. 
     The memory  240  comprises a plurality of storage locations that are addressable by the processor(s)  220  and the network interfaces  210  for storing software programs and data structures associated with the embodiments described herein. The processor  220  may comprise necessary elements or logic adapted to execute the software programs and manipulate the data structures  245 . An operating system  242  (e.g., the Internetworking Operating System, or IOS®, of Cisco Systems, Inc., another operating system, etc.), portions of which are typically resident in memory  240  and executed by the processor(s), functionally organizes the node by, inter alia, invoking network operations in support of software processors and/or services executing on the device. These software processors and/or services may comprise a network security process  248 . 
     It will be apparent to those skilled in the art that other processor and memory types, including various computer-readable media, may be used to store and execute program instructions pertaining to the techniques described herein. Also, while the description illustrates various processes, it is expressly contemplated that various processes may be embodied as modules configured to operate in accordance with the techniques herein (e.g., according to the functionality of a similar process). Further, while processes may be shown and/or described separately, those skilled in the art will appreciate that processes may be routines or modules within other processes. 
     In general, network security process  248  may be configured to perform any or all of the following tasks:
         1. Identifying and classifying devices in the network—this may entail, for example, determining the make, model, software configuration, type, etc. of a given device.   2. Discerning operational insights about a device—for example, network security process  248  may assess the traffic of a particular device, to determine what the device is doing, or attempting to do, via the network. Such information may take the form of device details and communication maps for the device. In further cases, the device functions and application flows may be converted into tags and/or events for presentation to a user interface. Further, process  248  may also track variable changes, to monitor the integrity of the industrial workflow.   3. Detecting anomalies—network security process  248  may also assess the behaviors of a device on the network, to determine whether its behaviors are anomalous. In various embodiments, this may entail network security process  248  determining whether the behavior of the device has changed significantly over time and/or does not fit the expected behavioral pattern for its classification. For example, if the device is identifies as being a temperature sensor that periodically sends temperature measurements to a supervisory service, but the device is instead communicating data elsewhere, process  248  may deem this behavior anomalous.       

     In various embodiments, network security process  248  may employ any number of machine learning techniques, to assess the gathered telemetry data regarding the traffic of the device. In general, machine learning is concerned with the design and the development of techniques that receive empirical data as input (e.g., telemetry data regarding traffic in the network) and recognize complex patterns in the input data. For example, some machine learning techniques use an underlying model M, whose parameters are optimized for minimizing the cost function associated to M, given the input data. For instance, in the context of classification, the model M may be a straight line that separates the data into two classes (e.g., labels) such that M=a*x+b*y+c and the cost function is a function of the number of misclassified points. The learning process then operates by adjusting the parameters a,b,c such that the number of misclassified points is minimal. After this optimization/learning phase, network security process  248  can use the model M to classify new data points, such as information regarding new traffic flows in the network. Often, M is a statistical model, and the cost function is inversely proportional to the likelihood of M, given the input data. 
     In various embodiments, network security process  248  may employ one or more supervised, unsupervised, or semi-supervised machine learning models. Generally, supervised learning entails the use of a training set of data, as noted above, that is used to train the model to apply labels to the input data. For example, the training data may include sample telemetry data that is “normal,” or “suspicious.” On the other end of the spectrum are unsupervised techniques that do not require a training set of labels. Notably, while a supervised learning model may look for previously seen attack patterns that have been labeled as such, an unsupervised model may instead look to whether there are sudden changes in the behavior of the network traffic. Semi-supervised learning models take a middle ground approach that uses a greatly reduced set of labeled training data. 
     Example machine learning techniques that network security process  248  can employ may include, but are not limited to, nearest neighbor (NN) techniques (e.g., k-NN models, replicator NN models, etc.), statistical techniques (e.g., Bayesian networks, etc.), clustering techniques (e.g., k-means, mean-shift, etc.), neural networks (e.g., reservoir networks, artificial neural networks, etc.), support vector machines (SVMs), logistic or other regression, Markov models or chains, principal component analysis (PCA) (e.g., for linear models), multi-layer perceptron (MLP) ANNs (e.g., for non-linear models), replicating reservoir networks (e.g., for non-linear models, typically for time series), random forest classification, or the like. 
     The performance of a machine learning model can be evaluated in a number of ways based on the number of true positives, false positives, true negatives, and/or false negatives of the model. For example, the false positives of the model may refer to the number of traffic flows that are incorrectly classified as malware-generated, anomalous, etc. Conversely, the false negatives of the model may refer to the number of traffic flows that the model incorrectly classifies as normal, when actually malware-generated, anomalous, etc. True negatives and positives may refer to the number of traffic flows that the model correctly classifies as normal or malware-generated, etc., respectively. Related to these measurements are the concepts of recall and precision. Generally, recall refers to the ratio of true positives to the sum of true positives and false negatives, which quantifies the sensitivity of the model. Similarly, precision refers to the ratio of true positives the sum of true and false positives. 
     In some cases, network security process  248  may assess the captured telemetry data on a per-flow basis. In other embodiments, network security process  248  may assess telemetry data for a plurality of traffic flows based on any number of different conditions. For example, traffic flows may be grouped based on their sources, destinations, temporal characteristics (e.g., flows that occur around the same time, etc.), combinations thereof, or based on any other set of flow characteristics. 
     As noted above, the very nature of the IoT presents certain challenges, from a security standpoint. Indeed, the diversity of the various devices in the network in terms of their hardware, software, and purposes (e.g., sensing, controlling, etc.), as well as the specific configuration of the network (e.g., cells in an industrial network, etc.), can make enforcing network security particularly challenging. 
     Best practices for Industrial IoT security typically follow standardized models, such as IEC  62443 . This security model implements both operational technology (OT) and information technology (IT) security levels and establishes how security should be designed in industrial systems. Furthermore, it describes how security between levels is accomplished through the use of controlled conduits. However, industrial security remains very difficult to enforce, as evidenced by recent industrial attacks where this model was in place. A superior approach would be to leverage intent-based networking, complete with abstraction, automation and analytics, to define, enforce and assure IoT security policies. 
     It is also important to recognize that IoT devices typically follow a very well prescribed communication profile (e.g., to which devices they should be communicating, on what protocol, and what the protocol should be doing). For instance, a supervisory control and data acquisition (SCADA) slave should only ever communicate to a SCADA master on an established port and should only execute allowable commands. However, it remains very difficult to both 1.) verify that the things, such as intelligent electronic devices, programmable logic controllers (PLCs), variable-frequency drive (VFD), human-machine interfaces (HMIs), input/output (I/O) controllers, etc., are communicating in the expected way and 2.) control their behaviors such that any unexpected network attacks are isolated. 
     Even when the communications between endpoints are seemingly innocuous, there has been a recent trend in malware taking advantage of these communications to damage equipment. In these forms of attacks, an infected endpoint can send control commands to another endpoint, with whom communication is allowed, that can damage or disrupt the operations of the equipment and, potentially, the industrial environment as a whole. For example, malicious SCADA commands to a PLC could cause the PLC to drive a motor in an unsafe way, cause power to be turned off or on to a circuit (e.g., a feeder in an electrical power station), or the like. 
     Telemetry Collection and Policy Enforcement Using Asset Tagging 
     The techniques herein introduce approaches to tag assets/devices in a network based on their telemetry data. In some aspects, this tagging can be used to drive network policy enforcement regarding the assets. 
     Illustratively, the techniques described herein may be performed by hardware, software, and/or firmware, such as in accordance with the network security process  248 , which may include computer executable instructions executed by the processor  220  (or independent processor of interfaces  210 ) to perform functions relating to the techniques described herein. 
     Specifically, according to various embodiments, a networking device in a network receives a policy for an endpoint device in the network. The policy specifies one or more component tags and one or more activity tags that were assigned to the endpoint device based on deep packet inspection of traffic associated with the endpoint device. The networking device identifies a set of tags for a particular traffic flow in the network associated with the endpoint device. The set of tags comprises one or more component tags or activity tags associated with the particular traffic flow. The networking device makes a determination that the particular traffic flow violates the policy based on the set of tags for the particular traffic flow comprising a tag that is not in the policy. The networking device initiates, based on the determination that the particular traffic flow violates the policy, a corrective measure with respect to the particular traffic flow. 
     Operationally,  FIG. 3  illustrates an example network architecture  300  for an industrial network, according to various embodiments. As shown, architecture  300  may include industrial equipment  304  connected to a controller  306 , such as a PLC, a VFD, or the like, that controls the operations of industrial equipment  304 . In turn, controller  306  for industrial equipment  304  may be connected to an HMI  310  via networking equipment  308 , allowing a human user to interface with it (e.g., to visualize the industrial process, issue commands, etc.). In addition, networking equipment  308  may also provide connectivity via the greater network  302  to any number of network services  312 - 320  provided in the local network of networking equipment  308  and/or remotely. For example, services  312 - 320  may be implemented in the local network via dedicated equipment or virtualized across any number of devices (e.g., networking equipment  308 ). In other cases, services  312 - 320  may be provided by servers in a remote data center, the cloud, or the like. 
     As would be appreciated, industrial equipment  304  may differ, depending on the industrial setting in which architecture  300  is implemented. In many cases, industrial equipment  304  may comprise an actuator such as, but not limited to, a motor, a pump, a solenoid, or the like. In other cases, industrial equipment  304  may include a circuit and controller  306  may control the powering of the circuit. 
     Industrial equipment  304  may also include any number of sensors configured to take measurements regarding the physical process implemented by industrial equipment  304 . For example, such sensors may take temperature readings, distance measurements, humidity readings, voltage or amperage measurements, or the like, and provide them to controller  306  for industrial equipment  304 . During operation, controller  306  may use the sensor data from industrial equipment  304  as part of a control loop, thereby allowing controller  306  to adjust the industrial process as needed. 
     HMI  310  may include a dedicated touch screen display or may take the form of a workstation, portable tablet or other handheld, or the like. Thus, during operation, visualization data may be provided to HMI  310  regarding the industrial process performed by industrial equipment  304 . For example, such visualizations may include a graphical representation of the industrial process (e.g., the filling of a tank, etc.), the sensor data from industrial equipment  304 , the control parameter values used by controller  306 , or the like. In some embodiments, HMI  310  may also allow for the reconfiguration of controller  306 , such as by adjusting its control parameters for industrial equipment  304  (e.g., to shut down the industrial process, etc.). 
     Networking equipment  308  may include any number of switches, routers, firewalls, telemetry exporters and/or collectors, gateways, bridges, and the like. In some embodiments, these networking functions may be performed in a virtualized/containerized manner. For example, a telemetry exporter may take the form of a containerized application installed to networking equipment  308 , to collect and export telemetry regarding the operation networking equipment  308  (e.g., queue state information, memory or processor resource utilization, etc.) and/or network  302  (e.g., measured delays, drops, jitter, etc.). 
     In some embodiments, at least a portion of network  302  may be implemented as a software-defined network (SDN). In such implementations, control plane decisions by the networking equipment of network  302 , such as networking equipment  308 , may be centralized with an SDN controller. For example, rather than networking equipment  308  establishing routing paths and making other control decisions, individually, such decisions can be centralized with an SDN controller (e.g., network supervisory service  312 , etc.). 
     During operation, network supervisory service  312  may function to monitor the status and health of network  302  and networking equipment  308 . An example of such a network supervisory service is DNA-Center by Cisco Systems, Inc. For example, in some implementations, network supervisory service  312  may take the form of a network assurance service that assesses the health of network  302  and networking equipment  308  through the use of heuristics, rules, and/or machine learning models. In some cases, this monitoring can also be predictive in nature, allowing network supervisory service  312  to predict failures and other network conditions before they actually occur. In either case, network supervisory service  312  may also provide control over network  302 , such as by reconfiguring networking equipment  308 , adjusting routing in network  302 , and the like. As noted above, network supervisory service  312  may also function as an SDN controller for networking equipment  308 , in some embodiments. 
     As shown, architecture  300  may also include SCADA service  314  which supervises the operation of the industrial process. More specifically, SCADA service  314  may communicate with controller  306 , to receive data regarding the industrial process (e.g., sensor data from industrial equipment  304 , etc.) and provide control over controller  306 , such as by pushing new control routines, software updates, and the like, to controller  306 . 
     As would be appreciated, SCADA service  314 , controller  306 , and/or HMI  310  may communicate using an automation protocol. Examples of such protocols may include, but are not limited to, Profibus, Modbus, DeviceNet, HART, DNP 3 , IEC 61850, IEC 60870-5, and the like. In addition, different protocols may be used within network  102  and among networking equipment  308 , depending on the specific implementation of architecture  300 . Further, different portions of network  302  may be organized into different cells or other segmented areas that are distinct from one another and interlinked via networking equipment  308 . 
     Architecture  300  may also include a policy service  316  that is responsible for creating and managing security and access policies for endpoints in network  302 . An example of such a policy service  316  is the Identity Services Engine (ISE) by Cisco Systems, Inc. In various embodiments, as detailed below, policy service  316  may also be configured to identify the types of endpoints present in network  302  (e.g., HMI  310 , controller  306 , etc.) and their corresponding actions/functions. In turn, this information can be used to drive the policies that policy service  316  creates. 
     Security service  318  is configured to enforce the various policies created and curated by policy service  316  in the network. For example, such policies may be implemented by security service  318  as access control lists (ACLs), firewall rules, or the like, that are distributed to networking equipment  308  for enforcement. 
     According to various embodiments, architecture  300  may also include asset inventory service  320  that is used to collect information about learned assets/endpoints in network  302  and maintain an inventory of these various devices in network  302 . In various embodiments, asset inventory service  320  may do so by embedding sensing modules in networking equipment  308  which passively analyze communications between endpoints. The sensors may use deep packet inspection (DPI) to not only identify the protocols in use by a given packet (e.g., the automation protocol used between HMI  310 , controller  306 , and SCADA service  314 ), but also understand the action(s) that are being communicated and to classify both the type of device/component and its application behavior. 
     For example, when a sensor module executed by networking equipment  308  identifies the use of an automation protocol by a packet, it may examine the payload of each flow to identify any or all of the following:
         The device type (e based on passive scan of traffic and known criterion, the device is classified).   The software and/or hardware versions of the device.   MAC and IP addresses of all devices with which the discovered device is communicating.   The activity profile of the device e.g., how is it trying to communicate), and the protocol(s) it is using.   The commands that are being passed (e.g., SCADA commands, etc.), down to the specific control parameter values.       

     The sensor modules of networking equipment  308  then then organize the collected information into meaningful tags. In general, these tags are simply a way to categorize devices and their behaviors, similar to the same way a human may look at a pen or a pencil and categorize them as writing instruments. Each device can also have multiple tags associated. with it, such as the following:
         Component Tags—these tags identify device specific details (e.g., Device ID, SCADA station, PLC, Windows device, etc.).   Activity Tags—these tags identify what the device is doing at the protocol level (Programming CPU, Heartbeat, Emergency Break, Data Push).   User-Defined Tags—these could be custom tags to supply additional context (e.g. “Cell 1 Tag”).   Dynamically Generated Tags—these could be added dynamically (e.g., using ML) to signify whether the behavior of the device is normal or anomalous, or for other dynamic conditions.   Scalable Group Tags—These tags are applied to specific packet flows between a defined group of devices/services in the network. For example, in the case shown, HMI  310 , controller  306 , and SCADA service  314  may be tagged as belonging to a particular group.       

     The sensor modules embedded in networking equipment  308  may also collect metadata about the communicating devices/endpoints, including its network identifiers (e.g., IP and MAC addresses), vendor, device-type, firmware version, the switch ID and port where the device is connected, etc. As the sensor module learns details of a new device/endpoint in network  302 , it may send its collected metadata about that device, along with its tags, to the asset inventory service  320 . 
     In this manner, asset inventory service  320  may maintain an inventory of each of the endpoint devices in network  302 , their associated tags, and their metadata. Thus, as new devices are discovered in network  302 , their profile information is added to the live inventory of devices maintained by asset inventory service  320 . As noted above, the various tags applied by the sensor modules deployed to networking equipment  308  and used by asset inventory service  320  may be predefined or may, via a user interface show) be user-defined. 
       FIGS. 4A-4B  illustrate example displays  400 ,  410 , respectively, showing component and activity tags, in some embodiments. As shown, the various component tags can be used to identify a particular endpoint or other device in the network by its type (e.g., PLC, SCADA station, etc.), its software (e.g., CodeSys, Windows, etc.). In addition, analysis of the traffic of the device can also lead to various activity tags being applied to that device, as well. For example, such activity tags may distinguish between control system behaviors (e.g., insert program, device init., etc.) and IT behaviors (e.g., host config., ping, etc.). 
     Referring again to  FIG. 3 , to facilitate the labeling of devices in network  302  using tags, asset inventory service  320  may also leverage device classification functions provided by policy service  316 , to identify the component and activity tags of a particular device in network  302  under scrutiny. In general, device classification (also known as “device profiling”) has traditionally used static rules and heuristics for the determination. In further embodiments, the device classification by policy service  316  can be achieved by applying a trained machine learning-based classifier to the captured telemetry data from networking equipment  308 . Such telemetry data can also take the form of information captured through active and/or passive probing of the device. Notably, this probing may entail policy service  316  sending any or all of the following probes via networking equipment  308 :
         Dynamic Host Configuration Protocol (DHCP) probes with helper addresses   SPAN probes, to get messages in INIT-REBOOT and SELECTING states, use of ARP cache for IP/MAC binding, etc.   Netflow probes   HyperText Transfer Protocol (HTTP) probes to obtain information such as the operating system (OS) of the device, Web browser information, etc.   Remote Authentication Dial-in User Service (RADIUS) probes.   Simple Network Management Protocol (SNMP) to retrieve Management Information Base (MIB) object or receives traps.   Domain Name System (DNS) probes to get the Fully Qualified Domain Name (FQDN)   etc.       

     Further information that may be captured by networking equipment  308  and reported via telemetry data to policy service  316  may include traffic behavioral characteristics of the traffic of a device, such as the communication protocols used, flow information, timing and pattern data, and the like. In addition, the telemetry data may be indicative of the operational intent of the endpoint device (e.g., controller  306 , HMI  310 , etc.). 
     According to various embodiments, additional information that policy service  316  and asset inventory service  320  may use to tag the various devices/components in network  302  may include any or all of the following:
         Manufacturer&#39;s Usage Description (MUD) information—As proposed in the Internet Engineering Task Force (IETF) draft entitled, “Manufacturer Usage Description Specification,” devices may be configured by their manufacturers to advertise their device specifications. Such information may also indicate the intended communication patterns of the devices.   Asset Administration Shell data—this is an Industry 4.0 method to express how an IoT device should behave including expected communication patterns.   IEC 61850 Substation Configuration Language (SCL) data this is a language that is used primarily in the utility industry to express Intelligent Electronic Device (IED) intent.   Open Platform Communication Unified Architecture (OPC UA) data—such data provides industrial models used in manufacturing contexts.       

     Thus, policy service  316 , asset inventory service  320 , and the sensor modules and telemetry exporters of networking equipment  308  may operate in conjunction with one another to apply various tags to the devices in network  302  and their traffic flows. 
       FIG. 5  illustrates an example display  500  of an asset profile, in some embodiments. Notably, the techniques herein have been implemented as part of a prototype system and display  500  represents an actual output from that prototype system. As can be seen, a particular asset has been identified as a Yokogawa device and has been tagged with various component and activity tags (e.g., PLC, CodeSys, Citect Report, etc.). This profile may be stored by the asset inventory service (e.g., service  320  in  FIG. 3 ) and provide to a user interface, allowing the user to quickly learn information about the device. Such information can also be automatically updated over time, using the techniques herein. 
     Referring again to  FIG. 3 , the various tags can also be used to augment flow telemetry, such as Netflow records, IPFIX records, or the like. To do so, asset inventory service  320  may propagate any of its stored tags to a Netflow collector or other telemetry exporter. As would be appreciated, such telemetry exporters typically build flow tables based on Netflow-9 metadata, such as 5-Tuple TCP/IP information, etc. However, such telemetry collectors and analyzers do not understand what the device is or how it should be operating. According to various embodiments, augmenting a telemetry exporter to understand the OT policy and intent of industrial devices allows for better enforcement of the allowed flows in an OT environment, and improves troubleshooting when a cyber incident occurs. 
     In various embodiments, by tagging the endpoint devices in network  300  in terms of what they are and what they should do, it becomes possible to automatically implement and enforce network policies and to quickly identify security threats. To do so, policy service  316  can be used to authenticate, authorize, and provide policies for specific endpoints and/or user in network  302 . Generic elements of such a policy may specify component, activity, or other tags. For example, a generic policy may be created for all PLCs in Cell Area Zone 1. Such a policy may specify a ‘PLC’ component tag, as well as activity tags indicative of what types of activities the PLCs are allowed to perform, what protocols they are allowed to communicate, and with whom they are allowed to communicate. For instance, controller  306  may be allowed to communicate with other industrial devices in the same Cell Area Zone, but not beyond. In another instance, controller  306  may only be allowed to communicate with an HMI in the same zone, such as HMI  310 . 
     Typically, a policy generated by policy service  316  will take the form of a logical combination of tags. For example, one policy may be as follows: 
     IF the device is a PLC AND is in CELL- 1  THEN it may talk to device-x 
     When this policy is deployed to networking equipment  308 , controller  306  may be allowed to communicate with HMI  310 , but may be restricted from communicating with other devices via network  302 . Notably, this can even lead to policies that are cell/zone specific in the OT network  302  (e.g., a PLC is restricted from communicating with other devices outside of its cell). 
     During operation, policy service  316  may receive updates from asset inventory service  320 , either periodically or on demand. This allows policy service  316  visibility into all of the discovered devices on the network, along with their tags and other metadata. Preferably, policy service  316  will use the same tag format as that of asset inventory service  320 . In turn, policy service  316  may create an entry for the device based on what has been discovered, with specific data updated based on information learned by the sensor in networking equipment  308  (e.g., the telemetry collector/exporter) and given through asset inventory service  320 . 
     By pushing a policy to networking equipment  308 , the corresponding networking equipment  308  can enforce the policy by applying it to any traffic flow in network  302 . If the traffic flow is then deemed non-compliant, the networking equipment  308  can initiate a corrective measure, such as blocking the flow from reaching its destination, raising an alarm, redirecting the flow, or the like. 
     Note that, in some cases, it may not be possible for policy service  316  to perform an exact match between a discovered device and an existing policy, through the use of tags alone. In such a situation, policy service  316  may leverage a machine learning classifier (e.g., a neural network or the like) to perform such a matching, using the tags and other metadata information about the device (e.g., its observed communication patterns, etc.). Note also that the deployed sensor(s) in networking equipment  308  can also update the tags for a particular device over time, as well. If this occurs, policy service  316  may re-evaluate the policy assigned to that device. 
     In some implementations, enforcement of the identified policy can be achieved by passing the policy to security service  318 . This can be achieved via application programming interface (API) export or, as noted above, by embedding the assigned tags directly into the telemetry exports that are ingested, parsed, and processed by the security processes of networking equipment  308 . In addition, the analyzer can group flows by their expected context, for purposes of visualizations. For instance, such a visualization could show all OT devices that are slaves of a particular SCADA master. 
       FIG. 6A  illustrates an example display  600  of the enhancement of traffic flow telemetry with tag information that identifies what types of devices are at each end of the flow and their contexts. Here, it can be seen that the traffic flows information regarding durations, protocols, ports, bytes, etc., can be enhanced by also tagging the endpoints by their tags indicative of their types (e.g., HMIs, Controllers, Rockwell Automation/Allen-Bradley, etc.), locations (e.g., Cell-2, etc.), and the like. 
     Referring again to  FIG. 3 , by comparing the flow details that have enhanced with the tag information to the deployed policy, the security mechanism can identify policy violations. For example, OT devices use very prescribed flows, such as SCADA service  314  being restricted to communicating with SCADA endpoints/slaves using a SCADA protocol. If a non-SCADA master is shown to be communicating with a SCADA device, even if the protocol and commands were valid, this would be considered a security violation by the enforcing networking equipment  308  and corrective measures initiated. 
     Said differently, when a new flow is generated, the telemetry collector/exporter may cross reference the IP address(es) of the new flow entry with the type or definition of the asset, to enhance the flow telemetry. In turn, the analyzer of such telemetry can then assess the tags and security policy assigned to the devices, to enforce the policy. 
       FIG. 6B  illustrates an example display  610  implementing the techniques herein. As shown, assume that the traffic flow record has been tagged with ‘Cell-1’ and ‘Cell-2’ tags by the asset inventory service (abbreviated AIS in  FIG. 6B ), indicating that the particular traffic flow is between these two different locations in the network. In turn, the analyzer may compare these tags to an existing policy named “Segmentation_Monitor_Policy” that applies to all inter-cell traffic flows. 
     Referring yet again to  FIG. 3 , in further embodiments, the policy enforcement can also rely on behavioral analytics, to identify any behavioral anomalies exhibited by an endpoint device. By tracking and updating the activity tags of a device over time using the above techniques, this effectively creates a baseline behavioral profile for that device. Thus, when its behavior suddenly deviates from its expected activities/behaviors, the analyzing networking equipment  308  can initiate a corrective measure. If a new activity tag is associated with the device, this can be compared with its associated policies, to determine whether this new behavior is still acceptable. 
     Since activity tags can be learned and updated over time, when a new device appears or disappears on network  302 , it may also be assigned a temporal tag to indicate that the device should be scrutinized. For example, if a device tagged as critical disappears from the network, a critical alarm could be raised. Similarly, when a new device suddenly appears on the network, it may be assigned a “new” tag and its behavior monitored to a higher degree and/or have more stringent policies applied to it. 
     For example, HMI  310  may be allowed to load a new program to controller  306 , but if a “new” PLC in network  302  similarly attempts to load a program to controller  306 , then an alarm may be triggered. 
     In one embodiment, the networking equipment  308  enforcing a policy may leverage a Naïve Bayes classifier or other suitable machine learning-based classifier, to determine whether the new device on the network presents a threat. The temporal tags can also be aged out over time, as the device&#39;s behavior is deemed normal over a defined period of time and is, thus, trustworthy. 
     In other words, when either a new endpoint device appears on network  302  or an existing endpoint device begins to operate in a new way (e.g., new tags are added or appear in its traffic flows), the networking equipment  308  enforcing the policies may compute and assess the probability that the endpoint device (and/or its behavior) is either benign or malicious. Data parameters, primarily the component and activity tags, as well as flow characteristics are used as input parameters for this computation. In some embodiments, these data points could also be clustered in an n-dimensional space, to profile both benign and malicious behavior from past events and devices. In turn, a Naïve Bayes classifier could create cluster boundaries for these clusters and classify the endpoint device under scrutiny as either benign or malicious, accordingly. 
       FIG. 6C  shows yet another display  620  representing an output of the prototype system implementing the techniques herein, demonstrating allowed activities for different devices. As shown, a particular station may be allowed to perform various control actions with respect to a set of rack devices. These allowable actions can then be translated into a corresponding tag-based policy that can be enforced within the OT network. 
       FIG. 7  illustrates an example simplified procedure for telemetry collection and policy enforcement using asset tagging, in accordance with one or more embodiments described herein. In various embodiments, a non-generic, specifically configured device (e.g., device  200 ) may perform procedure  700  by executing stored instructions (e.g., process  248 ), such as a networking device in a network. For instance, a network switch, a router, or other form of networking equipment may perform procedure  700 . The procedure  700  may start at step  705 , and continues to step  710 , where, as described in to greater detail above, the networking device may receive a policy for an endpoint device in the network. In various embodiments, the policy specifies one or more component tags and one or more activity tags that were assigned to the endpoint device based on deep packet inspection (DPI) of traffic associated with the endpoint device. 
     At step  715 , as detailed above, the networking device may identify a set of tags is for a particular traffic flow in the network associated with the endpoint device. In various embodiments, the set of tags comprises one or more component tags or activity tags associated with the particular traffic flow. For instance, the networking device may receive a traffic flow record for the particular traffic flow that includes the set of tags from a telemetry exporter. Such a telemetry exporter may perform DPI on the particular traffic flow and associate the set of tags with the flow as part of traffic flow record (e.g., a Netflow record, an IPFIX record, etc.). In various embodiments, the telemetry exporter may be executed directly on the networking device or on another device in communication therewith. 
     At step  720 , the networking device may make a determination that the particular traffic flow violates the policy based on the set of tags for the particular traffic flow comprising a tag that is not in the policy, as described in greater detail above. In some embodiments, the policy is indicative of a baseline behavioral profile for the endpoint device. In such cases, the networking device may make the determination by computing, based on the baseline behavioral profile for the endpoint device, a probability that the set of tags is indicative of an anomalous behavior of the endpoint device. For instance, the networking device may compute the probability using a Naïve Bayes classifier or other suitable machine learning model. By way of example, the anomalous behavior may correspond to the endpoint device attempting to install software to another endpoint device in the network. 
     At step  725 , as detailed above, the networking device may initiate, based on the determination that the particular traffic flow violates the policy, a corrective measure with respect to the particular traffic flow. In some embodiments, the networking device may block the particular traffic flow from being delivered to the endpoint device. In to other embodiments, the networking device may raise an alert, redirect the traffic flow, or the like. Procedure  700  then ends at step  730 . 
     The techniques described herein, therefore, introduce an architecture for an OT network that can automatically tag devices and their flows with component and activity information, automatically. In doing so, detailed network policies can he created and enforced by comparing the tags associated with a flow to the policies assigned to the communicating devices. 
     While there have been shown and described illustrative embodiments for telemetry collection and policy enforcement using asset tagging, it is to be understood that various other adaptations and modifications may be made within the intent and scope of the embodiments herein. For example, while specific endpoint device types are described, the techniques can be applied to any number of different types of devices. Further, while the techniques herein are described as being performed at certain locations within a network, the techniques herein could also be performed at other locations, as desired (e.g., fully in the cloud, fully within the local network, etc.). 
     The foregoing description has been directed to specific embodiments. It will be apparent, however, that other variations and modifications may be made to the described embodiments, with the attainment of some or all of their advantages. For instance, it is expressly contemplated that the components and/or elements described herein can be implemented as software being stored on a tangible (non-transitory) computer-readable medium (e.g., disks/CDs/RAM/EEPROM/etc.) having program instructions executing on a computer, hardware, firmware, or a combination thereof. Accordingly, this description is to be taken only by way of example and not to otherwise limit the scope of the embodiments herein. Therefore, it is the object of the appended claims to cover all such variations and modifications as come within the true intent and scope of the embodiments herein.