Patent Publication Number: US-2022224780-A1

Title: Adaptive tracing using one of a plurality of protocols

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present disclosure is a continuation-in-part of U.S. patent application Ser. No. 17/149,130, filed Jan. 14, 2021, and a continuation-in-part of U.S. patent application Ser. No. 17/193,019, filed Mar. 5, 2021, the contents of each are incorporated by reference in their entirety. 
    
    
     FIELD OF THE DISCLOSURE 
     The present disclosure relates generally to networking and computing. More particularly, the present disclosure relates to systems and methods for adaptive tracing using one of a plurality of protocols that is best suited. 
     BACKGROUND OF THE DISCLOSURE 
     The trend in Information Technology (IT) includes applications and resources being located in the cloud, users working from home or anywhere, and for the Internet becoming the new corporate network. As such, there is a need for IT to monitor and isolate issues affecting the user-to-cloud application experience. That is, there is a need for IT administrators to have visibility into the network and details of service paths. Various User Experience (UX or UEX) tools and approaches seek to quantify an individual user&#39;s satisfaction with a product or service such as a networking application. Examples include End User Experience Monitoring (EUEM) tools, Network Performance Monitoring and Diagnostics Market (NPMD) tools, Application Performance Monitoring (APM) tools, and Digital Experience Monitoring (DEM) tools. 
     One aspect of these tools includes network measurements, such as using a traceroute. There are various tools to collect information about possible network paths followed by traffic. These tools give a holistic view of the complete network path. Traceroute is used “trace routes” of paths and measure packet delays in Internet Protocol (IP) networks. Traceroute is a diagnostic command to find the routes (paths) and measures the latency to each hop. In traceroute, each node is called a hop, and the latency is the round trip from the user&#39;s machine to the hop. 
     With increasing network sniffing and network threats, many enterprises use encrypted tunnels. Also, cloud-based systems can forward traffic to the cloud using encrypted tunnels. For example, tunnels can be based on Generic Routing Encapsulation (GRE), Layer Two Tunneling Protocol (L2TP), Internet Protocol (IP) Security (IPsec), Virtual Private Networks (VPN), Hypertext Transfer Protocol (HTTP), Transmission Control Protocol (TCP), etc. Some of these tunnels are opaque to existing tools such as traceroute, causing the wrong details about network state. 
     Traceroute is used to detect latencies and packet loss across a network path, and conventionally traceroute is run manually using either Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), or User Datagram Protocol (UDP). Because of the manual operation, a user must try out ICMP, UDP, and TCP traceroute to try to get the latencies and packet loss across the network path. The conventional traceroute might not get the data for all the hops using the selected protocol. The traceroute packets go through the network&#39;s egress to the destination. The administrator of a company or an ISP typically blocks some protocol or ports for security purposes. For example, the administrator might block ICMP echo messages on the internal network and in this case only the data from routers on the Internet and destination will be available and thus resulting in partial data. The administrator might also restrict some port(s) for a particular protocol and the user will not be able to know which ports are allowed for TCP or UDP traceroute. 
     BRIEF SUMMARY OF THE DISCLOSURE 
     The present disclosure relates to various techniques for tracing with tunnels and cloud-based systems for determining measures of network performance. This disclosure describes an approach for adaptively finding the protocol that works best for the internal network and the destination. In various embodiments, the present disclosure includes a method having steps, a system including at least one processor and memory with instructions that, when executed, cause the at least one processor to implement the steps, and a non-transitory computer-readable medium having instructions stored thereon for programming at least one processor to perform the steps. The steps include obtaining policy information related to a trace; performing a plurality of traces, from a start point to an end point in a network, using the different protocols based on the policy information; evaluating which of the plurality of traces reach the end point, and evaluating any of average latency of the plurality of traces, average loss of the plurality of traces, and a number of hops found, for each of the plurality of traces that reach the end point; and selecting a protocol of the different protocols to use for the trace based on the evaluating. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present disclosure is illustrated and described herein with reference to the various drawings, in which like reference numbers are used to denote like system components/method steps, as appropriate, and in which: 
         FIG. 1  is a network diagram of a cloud-based system offering security as a service. 
         FIG. 2  is a network diagram of an example implementation of the cloud-based system. 
         FIG. 3  is a block diagram of a server that may be used in the cloud-based system of  FIGS. 1 and 2  or the like. 
         FIG. 4  is a block diagram of a user device that may be used with the cloud-based system of  FIGS. 1 and 2  or the like. 
         FIG. 5  is a network diagram of the cloud-based system illustrating an application on user devices with users configured to operate through the cloud-based system. 
         FIG. 6  is a network diagram of a Zero Trust Network Access (ZTNA) application utilizing the cloud-based system of  FIGS. 1 and 2 . 
         FIG. 7  is a network diagram of the cloud-based system of  FIGS. 1 and 2  in an application of digital experience monitoring. 
         FIG. 8  is a network diagram of the cloud-based system of  FIGS. 1 and 2  with various cloud tunnels, labeled as cloud tunnels, for forwarding traffic. 
         FIGS. 9 and 10  are flow diagrams of a cloud tunnel illustrating a control channel ( FIG. 9 ) and a data channel ( FIG. 10 ), with the tunnel illustrated between a client and a server. 
         FIG. 11  is a network diagram of a trace between a user and a destination with no tunnel in between. 
         FIG. 12  is a network diagram of a trace between a user and a destination with an opaque tunnel between a tunnel client and a tunnel server. 
         FIG. 13  is a flowchart of a process for detecting a tunnel between a user device and a destination. 
         FIG. 14  is a flowchart of a process for collecting network details in a trace where there is an opaque tunnel. 
         FIG. 15  is a flow diagram illustrating actions between the client (user device), the tunnel client, the egress router, the tunnel server, and the destination (node) in an example operation of the process of  FIGS. 13 and 14 . 
         FIG. 16  is a flowchart of a process for detection of network hops and latency through an opaque tunnel and detection misconfiguration of tunnels. 
         FIG. 17  is a flowchart of a process for detection of latency, packet drops, and network hops through a TCP tunnel using ICMP and UDP probes. 
         FIG. 18  is a flowchart of a process for detection of latency, packet drops, and network hops through a tunnel by tracing hops therein. 
         FIG. 19  is a network diagram illustrating a user connected to an enforcement node in a digital experience monitoring application. 
         FIG. 20  is a flow diagram illustrating actions between the client (user device), the application, the egress router, the enforcement node, and the destination in an example operation of the process of  FIGS. 13 and 14 , along with caching of trace results at the enforcement node. 
         FIG. 21  is a flowchart of a process for metric computation for trace probes using cached data to prevent a surge on destination servers. 
         FIG. 22  is a flowchart of a process for TCP trace using RST and SYN-ACK to determine destination reachability. 
         FIG. 23  is a network diagram with an excerpt of the network diagram of  FIG. 19  illustrating Legs 2 and 3 for illustrating adaptive probing. 
         FIG. 24  is a flowchart of an adaptive probe process for trace probes. 
         FIG. 25  is a network diagram of a network for illustrating an average latency calculation. 
         FIG. 26  is a diagram of the network of  FIG. 25  illustrating an operation. 
         FIGS. 27-30  illustrate an example operation of the average latency adjustment. 
         FIGS. 31-34  illustrate an example operation of the differential average latency adjustment. 
         FIG. 35  is a flowchart of a process for an accurate differential trace latency calculation between hops. 
         FIG. 36  is a flowchart of a process for an adaptive trace determination between two points in a network, such as a user device, an egress from an internal network, a cloud node, and a destination. 
     
    
    
     DETAILED DESCRIPTION OF THE DISCLOSURE 
     The present disclosure relates to various techniques for using tracing with tunnels and cloud-based systems for determining measures of network performance. This disclosure describes an approach for adaptively finding the protocol that works best for the internal network and the destination. 
     Also, the present disclosure relates to various techniques for using tracing with tunnels and cloud-based systems for determining measures of network performance. The various techniques are used to detect network hops, packet loss, and latency from a client to a destination as well as discover how the client connects to the Internet and if any proxies or firewalls are present in the path. For determining a connection to the Internet, the present disclosure includes a technique to detect tunnels. For determining proxies or firewalls, the present disclosure utilizes an Application Programming Interface (API) to detect an egress router&#39;s IP port on a client&#39;s network. Once the client has visibility of the path (i.e., tunnels, proxies, firewalls, etc.), the client can communicate, such as out of band, to request other devices to trace different legs. Note, in various descriptions, the term traceroute or trace can also include PING, such as the My Traceroute (MTR). Also, a traceroute is protocol dependent, and the present disclosure can be referred instead to a “cloudpath” that is protocol independent. 
     § 1.0 Example Cloud-Based System Architecture 
       FIG. 1  is a network diagram of a cloud-based system  100  offering security as a service. Specifically, the cloud-based system  100  can offer a Secure Internet and Web Gateway as a service to various users  102 , as well as other cloud services. In this manner, the cloud-based system  100  is located between the users  102  and the Internet as well as any cloud services  106  (or applications) accessed by the users  102 . As such, the cloud-based system  100  provides inline monitoring inspecting traffic between the users  102 , the Internet  104 , and the cloud services  106 , including Secure Sockets Layer (SSL) traffic. The cloud-based system  100  can offer access control, threat prevention, data protection, etc. The access control can include a cloud-based firewall, cloud-based intrusion detection, Uniform Resource Locator (URL) filtering, bandwidth control, Domain Name System (DNS) filtering, etc. The threat prevention can include cloud-based intrusion prevention, protection against advanced threats (malware, spam, Cross-Site Scripting (XSS), phishing, etc.), cloud-based sandbox, antivirus, DNS security, etc. The data protection can include Data Loss Prevention (DLP), cloud application security such as via a Cloud Access Security Broker (CASB), file type control, etc. 
     The cloud-based firewall can provide Deep Packet Inspection (DPI) and access controls across various ports and protocols as well as being application and user aware. The URL filtering can block, allow, or limit website access based on policy for a user, group of users, or entire organization, including specific destinations or categories of URLs (e.g., gambling, social media, etc.). The bandwidth control can enforce bandwidth policies and prioritize critical applications such as relative to recreational traffic. DNS filtering can control and block DNS requests against known and malicious destinations. 
     The cloud-based intrusion prevention and advanced threat protection can deliver full threat protection against malicious content such as browser exploits, scripts, identified botnets and malware callbacks, etc. The cloud-based sandbox can block zero-day exploits (just identified) by analyzing unknown files for malicious behavior. Advantageously, the cloud-based system  100  is multi-tenant and can service a large volume of the users  102 . As such, newly discovered threats can be promulgated throughout the cloud-based system  100  for all tenants practically instantaneously. The antivirus protection can include antivirus, antispyware, antimalware, etc. protection for the users  102 , using signatures sourced and constantly updated. The DNS security can identify and route command-and-control connections to threat detection engines for full content inspection. 
     The DLP can use standard and/or custom dictionaries to continuously monitor the users  102 , including compressed and/or SSL-encrypted traffic. Again, being in a cloud implementation, the cloud-based system  100  can scale this monitoring with near-zero latency on the users  102 . The cloud application security can include CASB functionality to discover and control user access to known and unknown cloud services  106 . The file type controls enable true file type control by the user, location, destination, etc. to determine which files are allowed or not. 
     For illustration purposes, the users  102  of the cloud-based system  100  can include a mobile device  110 , a headquarters (HQ)  112  which can include or connect to a data center (DC)  114 , Internet of Things (IoT) devices  116 , a branch office/remote location  118 , etc., and each includes one or more user devices (an example user device  300  is illustrated in  FIG. 5 ). The devices  110 ,  116 , and the locations  112 ,  114 ,  118  are shown for illustrative purposes, and those skilled in the art will recognize there are various access scenarios and other users  102  for the cloud-based system  100 , all of which are contemplated herein. The users  102  can be associated with a tenant, which may include an enterprise, a corporation, an organization, etc. That is, a tenant is a group of users who share a common access with specific privileges to the cloud-based system  100 , a cloud service, etc. In an embodiment, the headquarters  112  can include an enterprise&#39;s network with resources in the data center  114 . The mobile device  110  can be a so-called road warrior, i.e., users that are off-site, on-the-road, etc. Those skilled in the art will recognize a user  102  has to use a corresponding user device  300  for accessing the cloud-based system  100  and the like, and the description herein may use the user  102  and/or the user device  300  interchangeably. 
     Further, the cloud-based system  100  can be multi-tenant, with each tenant having its own users  102  and configuration, policy, rules, etc. One advantage of the multi-tenancy and a large volume of users is the zero-day/zero-hour protection in that a new vulnerability can be detected and then instantly remediated across the entire cloud-based system  100 . The same applies to policy, rule, configuration, etc. changes—they are instantly remediated across the entire cloud-based system  100 . As well, new features in the cloud-based system  100  can also be rolled up simultaneously across the user base, as opposed to selective and time-consuming upgrades on every device at the locations  112 ,  114 ,  118 , and the devices  110 ,  116 . 
     Logically, the cloud-based system  100  can be viewed as an overlay network between users (at the locations  112 ,  114 ,  118 , and the devices  110 ,  116 ) and the Internet  104  and the cloud services  106 . Previously, the IT deployment model included enterprise resources and applications stored within the data center  114  (i.e., physical devices) behind a firewall (perimeter), accessible by employees, partners, contractors, etc. on-site or remote via Virtual Private Networks (VPNs), etc. The cloud-based system  100  is replacing the conventional deployment model. The cloud-based system  100  can be used to implement these services in the cloud without requiring the physical devices and management thereof by enterprise IT administrators. As an ever-present overlay network, the cloud-based system  100  can provide the same functions as the physical devices and/or appliances regardless of geography or location of the users  102 , as well as independent of platform, operating system, network access technique, network access provider, etc. 
     There are various techniques to forward traffic between the users  102  at the locations  112 ,  114 ,  118 , and via the devices  110 ,  116 , and the cloud-based system  100 . Typically, the locations  112 ,  114 ,  118  can use tunneling where all traffic is forward through the cloud-based system  100 . For example, various tunneling protocols are contemplated, such as GRE, L2TP, IPsec, customized tunneling protocols, etc. The devices  110 ,  116 , when not at one of the locations  112 ,  114 ,  118  can use a local application that forwards traffic, a proxy such as via a Proxy Auto-Config (PAC) file, and the like. An application of the local application is the application  350  described in detail herein as a connector application. A key aspect of the cloud-based system  100  is all traffic between the users  102  and the Internet  104  or the cloud services  106  is via the cloud-based system  100 . As such, the cloud-based system  100  has visibility to enable various functions, all of which are performed off the user device in the cloud. 
     The cloud-based system  100  can also include a management system  120  for tenant access to provide global policy and configuration as well as real-time analytics. This enables IT administrators to have a unified view of user activity, threat intelligence, application usage, etc. For example, IT administrators can drill-down to a per-user level to understand events and correlate threats, to identify compromised devices, to have application visibility, and the like. The cloud-based system  100  can further include connectivity to an Identity Provider (IDP)  122  for authentication of the users  102  and to a Security Information and Event Management (SIEM) system  124  for event logging. The system  124  can provide alert and activity logs on a per-user  102  basis. 
       FIG. 2  is a network diagram of an example implementation of the cloud-based system  100 . In an embodiment, the cloud-based system  100  includes a plurality of enforcement nodes (EN)  150 , labeled as enforcement nodes  150 - 1 ,  150 - 2 ,  150 -N, interconnected to one another and interconnected to a central authority (CA)  152 . The nodes  150  and the central authority  152 , while described as nodes, can include one or more servers, including physical servers, virtual machines (VM) executed on physical hardware, etc. An example of a server is illustrated in  FIG. 4 . The cloud-based system  100  further includes a log router  154  that connects to a storage cluster  156  for supporting log maintenance from the enforcement nodes  150 . The central authority  152  provide centralized policy, real-time threat updates, etc. and coordinates the distribution of this data between the enforcement nodes  150 . The enforcement nodes  150  provide an onramp to the users  102  and are configured to execute policy, based on the central authority  152 , for each user  102 . The enforcement nodes  150  can be geographically distributed, and the policy for each user  102  follows that user  102  as he or she connects to the nearest (or other criteria) enforcement node  150 . Of note, the cloud-based system is an external system meaning it is separate from tenant&#39;s private networks (enterprise networks) as well as from networks associated with the devices  110 ,  116 , and locations  112 ,  118 . 
     The enforcement nodes  150  are full-featured secure internet gateways that provide integrated internet security. They inspect all web traffic bi-directionally for malware and enforce security, compliance, and firewall policies, as described herein, as well as various additional functionality. In an embodiment, each enforcement node  150  has two main modules for inspecting traffic and applying policies: a web module and a firewall module. The enforcement nodes  150  are deployed around the world and can handle hundreds of thousands of concurrent users with millions of concurrent sessions. Because of this, regardless of where the users  102  are, they can access the Internet  104  from any device, and the enforcement nodes  150  protect the traffic and apply corporate policies. The enforcement nodes  150  can implement various inspection engines therein, and optionally, send sandboxing to another system. The enforcement nodes  150  include significant fault tolerance capabilities, such as deployment in active-active mode to ensure availability and redundancy as well as continuous monitoring. 
     In an embodiment, customer traffic is not passed to any other component within the cloud-based system  100 , and the enforcement nodes  150  can be configured never to store any data to disk. Packet data is held in memory for inspection and then, based on policy, is either forwarded or dropped. Log data generated for every transaction is compressed, tokenized, and exported over secure Transport Layer Security (TLS) connections to the log routers  154  that direct the logs to the storage cluster  156 , hosted in the appropriate geographical region, for each organization. In an embodiment, all data destined for or received from the Internet is processed through one of the enforcement nodes  150 . In another embodiment, specific data specified by each tenant, e.g., only email, only executable files, etc., is processed through one of the enforcement nodes  150 . 
     Each of the enforcement nodes  150  may generate a decision vector D=[d 1 , d 2 , . . . , dn] for a content item of one or more parts C=[c 1 , c 2 , . . . , cm]. Each decision vector may identify a threat classification, e.g., clean, spyware, malware, undesirable content, innocuous, spam email, unknown, etc. For example, the output of each element of the decision vector D may be based on the output of one or more data inspection engines. In an embodiment, the threat classification may be reduced to a subset of categories, e.g., violating, non-violating, neutral, unknown. Based on the subset classification, the enforcement node  150  may allow the distribution of the content item, preclude distribution of the content item, allow distribution of the content item after a cleaning process, or perform threat detection on the content item. In an embodiment, the actions taken by one of the enforcement nodes  150  may be determinative on the threat classification of the content item and on a security policy of the tenant to which the content item is being sent from or from which the content item is being requested by. A content item is violating if, for any part C=[c 1 , c 2 , . . . , cm] of the content item, at any of the enforcement nodes  150 , any one of the data inspection engines generates an output that results in a classification of “violating.” 
     The central authority  152  hosts all customer (tenant) policy and configuration settings. It monitors the cloud and provides a central location for software and database updates and threat intelligence. Given the multi-tenant architecture, the central authority  152  is redundant and backed up in multiple different data centers. The enforcement nodes  150  establish persistent connections to the central authority  152  to download all policy configurations. When a new user connects to an enforcement node  150 , a policy request is sent to the central authority  152  through this connection. The central authority  152  then calculates the policies that apply to that user  102  and sends the policy to the enforcement node  150  as a highly compressed bitmap. 
     The policy can be tenant-specific and can include access privileges for users, websites and/or content that is disallowed, restricted domains, DLP dictionaries, etc. Once downloaded, a tenant&#39;s policy is cached until a policy change is made in the management system  120 . The policy can be tenant-specific and can include access privileges for users, websites and/or content that is disallowed, restricted domains, DLP dictionaries, etc. When this happens, all of the cached policies are purged, and the enforcement nodes  150  request the new policy when the user  102  next makes a request. In an embodiment, the enforcement node  150  exchange “heartbeats” periodically, so all enforcement nodes  150  are informed when there is a policy change. Any enforcement node  150  can then pull the change in policy when it sees a new request. 
     The cloud-based system  100  can be a private cloud, a public cloud, a combination of a private cloud and a public cloud (hybrid cloud), or the like. Cloud computing systems and methods abstract away physical servers, storage, networking, etc., and instead offer these as on-demand and elastic resources. The National Institute of Standards and Technology (NIST) provides a concise and specific definition which states cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction. Cloud computing differs from the classic client-server model by providing applications from a server that are executed and managed by a client&#39;s web browser or the like, with no installed client version of an application required. Centralization gives cloud service providers complete control over the versions of the browser-based and other applications provided to clients, which removes the need for version upgrades or license management on individual client computing devices. The phrase “Software as a Service” (SaaS) is sometimes used to describe application programs offered through cloud computing. A common shorthand for a provided cloud computing service (or even an aggregation of all existing cloud services) is “the cloud.” The cloud-based system  100  is illustrated herein as an example embodiment of a cloud-based system, and other implementations are also contemplated. 
     As described herein, the terms cloud services and cloud applications may be used interchangeably. The cloud service  106  is any service made available to users on-demand via the Internet, as opposed to being provided from a company&#39;s on-premises servers. A cloud application, or cloud app, is a software program where cloud-based and local components work together. The cloud-based system  100  can be utilized to provide example cloud services, including Zscaler Internet Access (ZIA), Zscaler Private Access (ZPA), and Zscaler Digital Experience (ZDX), all from Zscaler, Inc. (the assignee and applicant of the present application). Also, there can be multiple different cloud-based systems  100 , including ones with different architectures and multiple cloud services. The ZIA service can provide the access control, threat prevention, and data protection described above with reference to the cloud-based system  100 . ZPA can include access control, microservice segmentation, etc. The ZDX service can provide monitoring of user experience, e.g., Quality of Experience (QoE), Quality of Service (QoS), etc., in a manner that can gain insights based on continuous, inline monitoring. For example, the ZIA service can provide a user with Internet Access, and the ZPA service can provide a user with access to enterprise resources instead of traditional Virtual Private Networks (VPNs), namely ZPA provides Zero Trust Network Access (ZTNA). Those of ordinary skill in the art will recognize various other types of cloud services  106  are also contemplated. Also, other types of cloud architectures are also contemplated, with the cloud-based system  100  presented for illustration purposes. 
     § 2.0 User Device Application for Traffic Forwarding and Monitoring 
       FIG. 3  is a network diagram of the cloud-based system  100  illustrating an application  350  on user devices  300  with users  102  configured to operate through the cloud-based system  100 . Different types of user devices  300  are proliferating, including Bring Your Own Device (BYOD) as well as IT-managed devices. The conventional approach for a user device  300  to operate with the cloud-based system  100  as well as for accessing enterprise resources includes complex policies, VPNs, poor user experience, etc. The application  350  can automatically forward user traffic with the cloud-based system  100  as well as ensuring that security and access policies are enforced, regardless of device, location, operating system, or application. The application  350  automatically determines if a user  102  is looking to access the open Internet  104 , a SaaS app, or an internal app running in public, private, or the datacenter and routes mobile traffic through the cloud-based system  100 . The application  350  can support various cloud services, including ZIA, ZPA, ZDX, etc., allowing the best in class security with zero trust access to internal apps. As described herein, the application  350  can also be referred to as a connector application. 
     The application  350  is configured to auto-route traffic for seamless user experience. This can be protocol as well as application-specific, and the application  350  can route traffic with a nearest or best fit enforcement node  150 . Further, the application  350  can detect trusted networks, allowed applications, etc. and support secure network access. The application  350  can also support the enrollment of the user device  300  prior to accessing applications. The application  350  can uniquely detect the users  102  based on fingerprinting the user device  300 , using criteria like device model, platform, operating system, etc. The application  350  can support Mobile Device Management (MDM) functions, allowing IT personnel to deploy and manage the user devices  300  seamlessly. This can also include the automatic installation of client and SSL certificates during enrollment. Finally, the application  350  provides visibility into device and app usage of the user  102  of the user device  300 . 
     The application  350  supports a secure, lightweight tunnel between the user device  300  and the cloud-based system  100 . For example, the lightweight tunnel can be HTTP-based. With the application  350 , there is no requirement for PAC files, an IPsec VPN, authentication cookies, or user  102  setup. 
     § 3.0 Example Server Architecture 
       FIG. 4  is a block diagram of a server  200 , which may be used in the cloud-based system  100 , in other systems, or standalone. For example, the enforcement nodes  150  and the central authority  152  may be formed as one or more of the servers  200 . The server  200  may be a digital computer that, in terms of hardware architecture, generally includes a processor  202 , input/output (I/O) interfaces  204 , a network interface  206 , a data store  208 , and memory  210 . It should be appreciated by those of ordinary skill in the art that  FIG. 4  depicts the server  200  in an oversimplified manner, and a practical embodiment may include additional components and suitably configured processing logic to support known or conventional operating features that are not described in detail herein. The components ( 202 ,  204 ,  206 ,  208 , and  210 ) are communicatively coupled via a local interface  212 . The local interface  212  may be, for example, but not limited to, one or more buses or other wired or wireless connections, as is known in the art. The local interface  212  may have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, among many others, to enable communications. Further, the local interface  212  may include address, control, and/or data connections to enable appropriate communications among the aforementioned components. 
     The processor  202  is a hardware device for executing software instructions. The processor  202  may be any custom made or commercially available processor, a Central Processing Unit (CPU), an auxiliary processor among several processors associated with the server  200 , a semiconductor-based microprocessor (in the form of a microchip or chipset), or generally any device for executing software instructions. When the server  200  is in operation, the processor  202  is configured to execute software stored within the memory  210 , to communicate data to and from the memory  210 , and to generally control operations of the server  200  pursuant to the software instructions. The I/O interfaces  204  may be used to receive user input from and/or for providing system output to one or more devices or components. 
     The network interface  206  may be used to enable the server  200  to communicate on a network, such as the Internet  104 . The network interface  206  may include, for example, an Ethernet card or adapter or a Wireless Local Area Network (WLAN) card or adapter. The network interface  206  may include address, control, and/or data connections to enable appropriate communications on the network. A data store  208  may be used to store data. The data store  208  may include any of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, and the like)), nonvolatile memory elements (e.g., ROM, hard drive, tape, CDROM, and the like), and combinations thereof. 
     Moreover, the data store  208  may incorporate electronic, magnetic, optical, and/or other types of storage media. In one example, the data store  208  may be located internal to the server  200 , such as, for example, an internal hard drive connected to the local interface  212  in the server  200 . Additionally, in another embodiment, the data store  208  may be located external to the server  200  such as, for example, an external hard drive connected to the I/O interfaces  204  (e.g., SCSI or USB connection). In a further embodiment, the data store  208  may be connected to the server  200  through a network, such as, for example, a network-attached file server. 
     The memory  210  may include any of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, etc.)), nonvolatile memory elements (e.g., ROM, hard drive, tape, CDROM, etc.), and combinations thereof. Moreover, the memory  210  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  210  may have a distributed architecture, where various components are situated remotely from one another but can be accessed by the processor  202 . The software in memory  210  may include one or more software programs, each of which includes an ordered listing of executable instructions for implementing logical functions. The software in the memory  210  includes a suitable Operating System (O/S)  214  and one or more programs  216 . The operating system  214  essentially controls the execution of other computer programs, such as the one or more programs  216 , and provides scheduling, input-output control, file and data management, memory management, and communication control and related services. The one or more programs  216  may be configured to implement the various processes, algorithms, methods, techniques, etc. described herein. 
     § 4.0 Example user Device Architecture 
       FIG. 5  is a block diagram of a user device  300 , which may be used with the cloud-based system  100  or the like. Specifically, the user device  300  can form a device used by one of the users  102 , and this may include common devices such as laptops, smartphones, tablets, netbooks, personal digital assistants, MP3 players, cell phones, e-book readers, IoT devices, servers, desktops, printers, televisions, streaming media devices, and the like. The user device  300  can be a digital device that, in terms of hardware architecture, generally includes a processor  302 , I/O interfaces  304 , a network interface  306 , a data store  308 , and memory  310 . It should be appreciated by those of ordinary skill in the art that  FIG. 5  depicts the user device  300  in an oversimplified manner, and a practical embodiment may include additional components and suitably configured processing logic to support known or conventional operating features that are not described in detail herein. The components ( 302 ,  304 ,  306 ,  308 , and  302 ) are communicatively coupled via a local interface  312 . The local interface  312  can be, for example, but not limited to, one or more buses or other wired or wireless connections, as is known in the art. The local interface  312  can have additional elements, which are omitted for simplicity, such as controllers, buffers (caches), drivers, repeaters, and receivers, among many others, to enable communications. Further, the local interface  312  may include address, control, and/or data connections to enable appropriate communications among the aforementioned components. 
     The processor  302  is a hardware device for executing software instructions. The processor  302  can be any custom made or commercially available processor, a CPU, an auxiliary processor among several processors associated with the user device  300 , a semiconductor-based microprocessor (in the form of a microchip or chipset), or generally any device for executing software instructions. When the user device  300  is in operation, the processor  302  is configured to execute software stored within the memory  310 , to communicate data to and from the memory  310 , and to generally control operations of the user device  300  pursuant to the software instructions. In an embodiment, the processor  302  may include a mobile optimized processor such as optimized for power consumption and mobile applications. The I/O interfaces  304  can be used to receive user input from and/or for providing system output. User input can be provided via, for example, a keypad, a touch screen, a scroll ball, a scroll bar, buttons, a barcode scanner, and the like. System output can be provided via a display device such as a Liquid Crystal Display (LCD), touch screen, and the like. 
     The network interface  306  enables wireless communication to an external access device or network. Any number of suitable wireless data communication protocols, techniques, or methodologies can be supported by the network interface  306 , including any protocols for wireless communication. The data store  308  may be used to store data. The data store  308  may include any of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, and the like)), nonvolatile memory elements (e.g., ROM, hard drive, tape, CDROM, and the like), and combinations thereof. Moreover, the data store  308  may incorporate electronic, magnetic, optical, and/or other types of storage media. 
     The memory  310  may include any of volatile memory elements (e.g., random access memory (RAM, such as DRAM, SRAM, SDRAM, etc.)), nonvolatile memory elements (e.g., ROM, hard drive, etc.), and combinations thereof. Moreover, the memory  310  may incorporate electronic, magnetic, optical, and/or other types of storage media. Note that the memory  310  may have a distributed architecture, where various components are situated remotely from one another but can be accessed by the processor  302 . The software in memory  310  can include one or more software programs, each of which includes an ordered listing of executable instructions for implementing logical functions. In the example of  FIG. 3 , the software in the memory  310  includes a suitable operating system  314  and programs  316 . The operating system  314  essentially controls the execution of other computer programs and provides scheduling, input-output control, file and data management, memory management, and communication control and related services. The programs  316  may include various applications, add-ons, etc. configured to provide end user functionality with the user device  300 . For example, example programs  316  may include, but not limited to, a web browser, social networking applications, streaming media applications, games, mapping and location applications, electronic mail applications, financial applications, and the like. In a typical example, the end-user typically uses one or more of the programs  316  along with a network such as the cloud-based system  100 . 
     § 5.0 Zero Trust Network Access using the Cloud-Based System 
       FIG. 6  is a network diagram of a Zero Trust Network Access (ZTNA) application utilizing the cloud-based system  100 . For ZTNA, the cloud-based system  100  can dynamically create a connection through a secure tunnel between an endpoint (e.g., users  102 A,  102 B) that are remote and an on-premises connector  400  that is either located in cloud file shares and applications  402  and/or in an enterprise network  410  that includes enterprise file shares and applications  404 . The connection between the cloud-based system  100  and on-premises connector  400  is dynamic, on-demand, and orchestrated by the cloud-based system  100 . A key feature is its security at the edge—there is no need to punch any holes in the existing on-premises firewall. The connector  400  inside the enterprise (on-premises) “dials out” and connects to the cloud-based system  100  as if too were an endpoint. This on-demand dial-out capability and tunneling authenticated traffic back to the enterprise is a key differentiator for ZTNA. Also, this functionality can be implemented in part by the application  350  on the user device  300 . Also, the applications  402 ,  404  can include B 2 B applications. Note, the difference between the applications  402 ,  404  is the applications  402  are hosted in the cloud, whereas the applications  404  are hosted on the enterprise network  410 . The B 2 B service described herein contemplates use with either or both of the applications  402 ,  404 . 
     The paradigm of virtual private access systems and methods is to give users network access to get to an application and/or file share, not to the entire network. If a user is not authorized to get the application, the user should not be able even to see that it exists, much less access it. The virtual private access systems and methods provide an approach to deliver secure access by decoupling applications  402 ,  404  from the network, instead of providing access with a connector  400 , in front of the applications  402 ,  404 , an application on the user device  300 , a central authority  152  to push policy, and the cloud-based system  100  to stitch the applications  402 ,  404  and the software connectors  400  together, on a per-user, per-application basis. 
     With the virtual private access, users can only see the specific applications  402 ,  404  allowed by the central authority  152 . Everything else is “invisible” or “dark” to them. Because the virtual private access separates the application from the network, the physical location of the application  402 ,  404  becomes irrelevant—if applications  402 ,  404  are located in more than one place, the user is automatically directed to the instance that will give them the best performance. The virtual private access also dramatically reduces configuration complexity, such as policies/firewalls in the data centers. Enterprises can, for example, move applications to Amazon Web Services or Microsoft Azure, and take advantage of the elasticity of the cloud, making private, internal applications behave just like the marketing leading enterprise applications. Advantageously, there is no hardware to buy or deploy because the virtual private access is a service offering to end-users and enterprises. 
     § 6.0 Digital Experience Monitoring 
       FIG. 7  is a network diagram of the cloud-based system  100  in an application of digital experience monitoring. Here, the cloud-based system  100  providing security as a service as well as ZTNA, can also be used to provide real-time, continuous digital experience monitoring, as opposed to conventional approaches (synthetic probes). A key aspect of the architecture of the cloud-based system  100  is the inline monitoring. This means data is accessible in real-time for individual users from end-to-end. As described herein, digital experience monitoring can include monitoring, analyzing, and improving the digital user experience. 
     The cloud-based system  100  connects users  102  at the locations  110 ,  112 ,  118  to the applications  402 ,  404 , the Internet  104 , the cloud services  106 , etc. The inline, end-to-end visibility of all users enables digital experience monitoring. The cloud-based system  100  can monitor, diagnose, generate alerts, and perform remedial actions with respect to network endpoints, network components, network links, etc. The network endpoints can include servers, virtual machines, containers, storage systems, or anything with an IP address, including the Internet of Things (IoT), cloud, and wireless endpoints. With these components, these network endpoints can be monitored directly in combination with a network perspective. Thus, the cloud-based system  100  provides a unique architecture that can enable digital experience monitoring, network application monitoring, infrastructure component interactions, etc. Of note, these various monitoring aspects require no additional components—the cloud-based system  100  leverages the existing infrastructure to provide this service. 
     Again, digital experience monitoring includes the capture of data about how end-to-end application availability, latency, and quality appear to the end user from a network perspective. This is limited to the network traffic visibility and not within components, such as what application performance monitoring can accomplish. Networked application monitoring provides the speed and overall quality of networked application delivery to the user in support of key business activities. Infrastructure component interactions include a focus on infrastructure components as they interact via the network, as well as the network delivery of services or applications. This includes the ability to provide network path analytics. 
     The cloud-based system  100  can enable real-time performance and behaviors for troubleshooting in the current state of the environment, historical performance and behaviors to understand what occurred or what is trending over time, predictive behaviors by leveraging analytics technologies to distill and create actionable items from the large dataset collected across the various data sources, and the like. The cloud-based system  100  includes the ability to directly ingest any of the following data sources network device-generated health data, network device-generated traffic data, including flow-based data sources inclusive of NetFlow and IPFIX, raw network packet analysis to identify application types and performance characteristics, HTTP request metrics, etc. The cloud-based system  100  can operate at 10 gigabits (10G) Ethernet and higher at full line rate and support a rate of 100,000 or more flows per second or higher. 
     The applications  402 ,  404  can include enterprise applications, Office 365, Salesforce, Skype, Google apps, internal applications, etc. These are critical business applications where user experience is important. The objective here is to collect various data points so that user experience can be quantified for a particular user, at a particular time, for purposes of analyzing the experience as well as improving the experience. In an embodiment, the monitored data can be from different categories, including application-related, network-related, device-related (also can be referred to as endpoint-related), protocol-related, etc. Data can be collected at the application  350  or the cloud edge to quantify user experience for specific applications, i.e., the application-related and device-related data. The cloud-based system  100  can further collect the network-related and the protocol-related data (e.g., Domain Name System (DNS) response time). 
     Application-Related Data 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 Page Load Time 
                 Redirect count (#) 
               
               
                   
                 Page Response Time 
                 Throughput (bps) 
               
               
                   
                 Document Object Model 
                 Total size (bytes) 
               
               
                   
                 (DOM) Load Time 
               
               
                   
                 Total Downloaded bytes 
                 Page error count (#) 
               
               
                   
                 App availability (%) 
                 Page element count by 
               
               
                   
                   
                 category (#) 
               
               
                   
                   
               
            
           
         
       
     
     Network-Related Data 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 HTTP Request metrics 
                 Bandwidth 
               
               
                   
                 Server response time 
                 Jitter 
               
               
                   
                 Ping packet loss (%) 
                 Trace Route 
               
               
                   
                 Ping round trip 
                 DNS lookup trace 
               
               
                   
                 Packet loss (%) 
                 GRE/IPSec tunnel monitoring 
               
               
                   
                 Latency 
                 MTU and bandwidth measurements 
               
               
                   
                   
               
            
           
         
       
     
     Device-Related Data (Endpoint-Related Data) 
     
       
         
           
               
               
               
             
               
                   
                   
               
             
            
               
                   
                 System details 
                 Network (config) 
               
               
                   
                 Central Processing Unit (CPU) 
                 Disk 
               
               
                   
                 Memory (RAM) 
                 Processes 
               
               
                   
                 Network (interfaces) 
                 Applications 
               
               
                   
                   
               
            
           
         
       
     
     Metrics could be combined. For example, device health can be based on a combination of CPU, memory, etc. Network health could be a combination of Wi-Fi/LAN connection health, latency, etc. Application health could be a combination of response time, page loads, etc. The cloud-based system  100  can generate service health as a combination of CPU, memory, and the load time of the service while processing a user&#39;s request. The network health could be based on the number of network path(s), latency, packet loss, etc. 
     The lightweight connector  400  can also generate similar metrics for the applications  402 ,  404 . In an embodiment, the metrics can be collected while a user is accessing specific applications that user experience is desired for monitoring. In another embodiment, the metrics can be enriched by triggering synthetic measurements in the context of an inline transaction by the application  350  or cloud edge. The metrics can be tagged with metadata (user, time, app, etc.) and sent to a logging and analytics service for aggregation, analysis, and reporting. Further, network administrators can get UEX reports from the cloud-based system  100 . Due to the inline nature and the fact the cloud-based system  100  is an overlay (in-between users and services/applications), the cloud-based system  100  enables the ability to capture user experience metric data continuously and to log such data historically. As such, a network administrator can have a long-term detailed view of the network and associated user experience. 
     § 7.0 Cloud Tunnel 
       FIG. 8  is a network diagram of the cloud-based system  100  with various cloud tunnels  500 , labeled as cloud tunnels  500 A,  500 B,  500 C, for forwarding traffic.  FIGS. 9 and 10  are flow diagrams of a cloud tunnel  500  illustrating a control channel ( FIG. 9 ) and a data channel ( FIG. 10 ), with the tunnel illustrated between a client  510  and a server  520 . The cloud tunnel  500  is a lightweight tunnel that is configured to forward traffic between the client  510  and the server  520 . The present disclosure focuses on the specific mechanisms used in the cloud tunnel  500  between two points, namely the client  510  and the server  520 . Those skilled in the art will recognize the cloud tunnel  500  can be used with the cloud-based system  100  as an example use case, and other uses are contemplated. That is, the client  510  and the server  520  are just endpoint devices that support the exchange of data traffic and control traffic for the tunnel  500 . For description, the server  520  can be referred to as a local node and the client  510  as a remote node, where the tunnel operates between the local and remote nodes. 
     In an embodiment, the cloud-based system  100  can use the cloud tunnel  500  to forward traffic to the enforcement nodes  150 , such as from a user device  300  with the application  350 , from a branch office/remote location  118 , etc.  FIG. 8  illustrates three example use cases for the cloud tunnel  500  with the cloud-based system  100 , and other uses are also contemplated. In a first use case, a cloud tunnel  500 A is formed between a user device  300 , such as with the application  350 , and an enforcement node  150 - 1 . For example, when a user  102  associated with the user device  300  connects to a network, the application  350  can establish the cloud tunnel  500 A to the closest or best enforcement node  150 - 1 , and forward the traffic through the cloud tunnel  500 A so that the enforcement node  150 - 1  can apply the appropriate security and access policies. Here, the cloud tunnel  500 A supports a single user  102 , associated with the user device  300 . 
     In a second use case, a cloud tunnel  500 B is formed between a Virtual Network Function (VNF)  502  or some other device at a remote location  118 A and an enforcement node  150 - 2 . Here, the VNF  502  is used to forward traffic from any user  102  at the remote location  118 A to the enforcement node  150 - 2 . In a third use case, a cloud tunnel  110 C is formed between an on-premises enforcement node, referred to as an Edge Connector (EC)  150 A, and an enforcement node  150 -N. The edge connector  150 A can be located at a branch office  118 A or the like. In some embodiments, the edge connector  150 A can be an enforcement node  150  in the cloud-based system  100  but located on-premises with a tenant. Here, in the second and third use cases, the cloud tunnels  500 B,  500 C support multiple users  102 . 
     There can be two versions of the cloud tunnel  500 , referred to a tunnel  1  and tunnel  2 . The tunnel  1  can only support Web protocols as an HTTP connect tunnel operating on a TCP streams. That is, the tunnel  1  can send all proxy-aware traffic or port 80/443 traffic to the enforcement node  150 , depending on the forwarding profile configuration. This can be performed via CONNECT requests, similar to a traditional proxy. 
     The tunnel  2  can support multiple ports and protocols, extending beyond only web protocols. As described herein, the cloud tunnels  500  are the tunnel  2 . In all of the use cases, the cloud tunnel  500  enables each user device  300  to redirect traffic destined to all ports and protocols to a corresponding enforcement node  150 . Note, the cloud-based system  100  can include load balancing functionality to spread the cloud tunnels  500  from a single source IP address. The cloud tunnel  500  supports device logging for all traffic, firewall, etc., such as in the storage cluster  156 . The cloud tunnel  500  utilizes encryption, such as via TLS or DTLS, to tunnel packets between the two points, namely the client  510  and the server  520 . As described herein, the client  510  can be the user device  300 , the VNF  502 , and/or the edge connector  150 A, and the server  520  can be the enforcement node  150 . Again, other devices are contemplated with the cloud tunnel  500 . 
     The cloud tunnel  500  can use a Network Address Translation (NAT) device that does not require a different egress IP for each device&#39;s  300  separate sessions. Again, the cloud tunnel  500  has a tunneling architecture that uses DTLS or TLS to send packets to the cloud-based system  100 . Because of this, the cloud tunnel  500  is capable of sending traffic from all ports and protocols. 
     Thus, the cloud tunnel  500  provides complete protection for a single user  102 , via the application  350 , as well as for multiple users at remote locations  118 , including multiple security functions such as cloud firewall, cloud IPS, etc. The cloud tunnel  500  includes user-level granularity of the traffic, enabling different users  102  on the same cloud tunnel  500  for the enforcement nodes  150  to provide user-based granular policy and visibility. In addition to user-level granularity, the cloud tunnel  500  can provide application-level granularity, such as by mapping mobile applications (e.g., Facebook, Gmail, etc.) to traffic, allowing for app-based granular policies. 
       FIGS. 9 and 10  illustrate the two communication channels, namely a control channel  530  and a data channel  540 , between the client  510  and the server  520 . Together, these two communication channels  530 ,  540  form the cloud tunnel  500 . In an embodiment, the control channel  530  can be an encrypted TLS connection or SSL connection, and the control channel  530  is used for device and/or user authentication and other control messages. In an embodiment, the data channel  540  can be an encrypted DTLS or TLS connection, i.e., the data channel can be one or more DTLS or TLS connections for the transmit and receive of user IP packets. There can be multiple data channels  540  associated with the same control channel  530 . The data channel  540  can be authenticated using a Session Identifier (ID) from the control channel  530 . 
     Of note, the control channel  530  always uses TLS because some locations (e.g., the remote location  118 A, the branch office  118 B, other enterprises, hotspots, etc.) can block UDP port 443, preventing DTLS. Whereas TLS is widely used and not typically blocked. The data channel  540  preferably uses DTLS, if it is available, i.e., not blocked on the client  510 . If it is blocked, the data channel  540  can use TLS instead. For example, DTLS is the primary protocol for the data channel  540  with TLS used as a fallback over TCP port 443 if DTLS is unavailable, namely if UDP port 443 is blocked at the client  510 . 
     In  FIG. 9 , the control channel  530  is illustrated with exchanges between the client  510  and the server  520 . Again, the control channel  530  includes TLS encryption, which is established through a setup or handshake between the client  510  and the server  520  (step  550 - 1 ). An example of a handshake is illustrated in  FIG. 11 . The client  510  can send its version of the tunnel  500  to the server  520  (step  550 - 2 ) to which the server  520  can acknowledge (step  550 - 3 ). For example, the version of the tunnel can include a simple version number or other indication, as well as an indication of whether the client  510  supports DTLS for the data channel  540 . Again, the control channel  530  is fixed with TLS or SSL, but the data channel  540  can be either DTLS or TLS. 
     The client  510  can perform device authentication (step  550 - 4 ), and the server  520  can acknowledge the device authentication (step  550 - 5 ). The client  510  can perform user authentication (step  550 - 6 ), and the server  520  can acknowledge the user authentication (step  550 - 7 ). Note, the device authentication includes authenticating the user device  300 , such as via the application  350 , the VNF  502 , the edge connector  150 A, etc. The user authentication includes authenticating the users  102  associated with the user devices  300 . Note, in an embodiment, the client  510  is the sole device  300 , and here the user authentication can be for the user  102  associated with the client  510 , and the device authentication can be for the user device  300  with the application  350 . In another embodiment, the client  510  can have multiple user devices  300  and corresponding users  102  associated with it. Here, the device authentication can be for the VNF  502 , the edge connector  150 A, etc., and the user authentication can be for each user device  300  and corresponding user  102 , and the client  510  and the server  520  can have a unique identifier for each user device  300 , for user-level identification. 
     The device authentication acknowledgment can include a session identifier (ID) that is used to bind the control channel  530  with one or more data channels  540 . The user authentication can be based on a user identifier (ID) that is unique to each user  102 . The client  510  can periodically provide keep alive packets (step  550 - 8 ), and the server  520  can respond with keep alive acknowledgment packets (step  550 - 9 ). The client  510  and the server  520  can use the keep alive packets or messages to maintain the control channel  530 . Also, the client  510  and the server  520  can exchange other relevant data over the control channel  530 , such as metadata, which identifies an application for a user  102 , location information for a user device  300 , etc. 
     In  FIG. 10 , similar to  FIG. 9 , the data channel  540  is illustrated with exchanges between the client  510  and the server  520 . Again, the data channel  540  includes TLS or DTLS encryption, which is established through a setup or handshake between the client  510  and the server  520  (step  560 - 1 ). An example of a handshake is illustrated in  FIG. 11 . Note, the determination of whether to use TLS or DTLS is based on the session ID, which is part of the device authentication acknowledgment, and which is provided over the data channel  540  (steps  560 - 2 ,  560 - 3 ). Here, the client  510  has told the server  520  its capabilities, and the session ID reflects what the server  520  has chosen, namely TLS or DTLS, based on the client&#39;s  510  capabilities. In an embodiment, the server  520  chooses DTLS if the client  510  supports it, i.e., if UDP port 443 is not blocked, otherwise the server  520  chooses TLS. Accordingly, the control channel  530  is established before the data channel  540 . The data channel  540  can be authenticated based on the session ID from the control channel  530 . 
     The data channel  540  includes the exchange of data packets between the client  510  and the server  520  (step  560 - 4 ). The data packets include an identifier such as the session ID and a user ID for the associated user  102 . Additionally, the data channel  540  can include keep alive packets between the client  510  and the server  520  (steps  560 - 5 ,  560 - 6 ). 
     The cloud tunnel  500  can support load balancing functionality between the client  510  and the server  520 . The server  520  can be in a cluster, i.e., multiple servers  200 . For example, the server  520  can be an enforcement node  150  cluster in the cloud-based system  100 . Because there can be multiple data channels  540  for a single control channel  530 , it is possible to have the multiple data channels  540 , in a single cloud tunnel  500 , connected to different physical servers  200  in a cluster. Thus, the cloud-based system  100  can include load balancing functionality to spread the cloud tunnels  500  from a single source IP address, i.e., the client  510 . 
     Also, the use of DTLS for the data channels  540  allows the user devices  300  to switch networks without potentially impacting the traffic going through the tunnel  500 . For example, a large file download could continue uninterrupted when a user device  300  moves from Wi-Fi to mobile, etc. Here, the application  350  can add some proprietary data to the DTLS client-hello servername extension. That proprietary data helps a load balancer balance the new DTLS connection to the same server  200  in a cluster where the connection prior to network change was being processed. So, a newly established DTLS connection with different IP address (due to network change) can be used to tunnel packets of the large file download that was started before the network change. Also, some mobile carriers use different IP addresses for TCP/TLS (control channel) and UDP/DTLS (data channel) flows. The data in DTLS client-hello helps the load balancer balance the control and data connection to the same server  200  in the cluster. 
     § 8.0 Traceroute 
     Traceroute can be based on Internet Control Message Protocol (ICMP), TCP, User Datagram Protocol (UDP), etc. For example, a traceroute based on ICMP provides all hops on the network. TCP and UDP are also supported by most clients, if ICMP is blocked. The response from the traceroute provides a holistic view of the network with packet loss details and latency details.  FIG. 11  is a network diagram of a traceroute between a user  102  and a destination  640  with no tunnel in between. Here, the user  102  (via a user device  300 ) connects to an access point  600 , which connects to the destination  640  via routers  602 A- 602 D and a switch  604 . The traceroute includes transmitting a request packet from the user  102  to the destination  640  (with an address of a.b.c.d) via the access point  600 , the routers  602 , and the switch  604 . Each of these intermediate devices  600 ,  602 ,  604  process the request packet and the enforcement node  150  sends a response packet back to the user  102 , which is also processed by the intermediate devices  600 ,  602 ,  604 . Accordingly, all hops in the network are visible. 
       FIG. 12  is a network diagram of a trace between a user  102  and the destination  640  with an opaque tunnel  610  between a tunnel client  510  and a tunnel server  520 . The opaque tunnel  610  can be the tunnel  500  as well as a GRE, IPsec, VPN, etc. The opaque tunnel  610  is referred to as opaque because there is no visibility into the tunnel. The traceroute in  FIG. 12 , based on ICMP, TCP, UDP, etc., provides visibility of the hops before and after the opaque tunnel  610 , but does not provide visibility in the opaque tunnel  610 . There are no details about packet loss or latency while tunneled transmission. Also, the opaque tunnel  610  can be referred to as an overlay tunnel. 
     Traceroute includes a series of packets that are exchanged from a probe initiator along a path. Each trace packet includes an increasing TTL value. When a node along the path receives a trace packet where the TTL expires, it sends a response. Based on all of the responses, it is possible for the probe initiator (e.g., the client) to determine the network hops, the latency at each hop, packet loss, and other details. Again, the traceroute can be an MTR, which also includes PING functionality. Again, MTR is used to traceroute the destination to show the latency, packet loss, and hop information between an initiator and destination. It helps to understand the network status and diagnose network issues. 
     In an embodiment, MTR is implemented on the user device  300 , such as through the application  350 , and on the tunnel server  520  and/or the enforcement node  150 . As is described herein, there is a requirement to implement probes at two points in the service path—at the client and at the tunnel server  520  and/or the enforcement node  150 . The MTR implementation can support ICMP, UDP, and/or TCP. For ICMP, two sockets are used to send and receive probes, and the ICMP sequence number in reply messages are used to match ICMP request messages. For UDP, one UDP socket is created to send UDP probes, and one ICMP socket is created to receive ICMP error messages. For TCP, one raw socket is created to send TCP probes, and one ICMP socket is created to receive ICMP error messages, and the TCP socket is also used to receive SYN-ACK/RST from the destination. The foregoing functionality can be performed by the application  350  on the user device  300  and a tracing service on the enforcement node  150 . SYN =Synchronize, ACK =Acknowledgment, and RST =Reset. 
     § 8.1 Detecting Opaque Tunnel 
       FIG. 13  is a flowchart of a process  650  for detecting a tunnel  500 ,  610  between a user device  300  and a destination. The process  650  is described with reference to the network in  FIG. 12  with actions at the user device  300 , the intermediate devices  600 ,  602 ,  604 , and the tunnel server  520 . Also, note that while the enforcement node  150  and the tunnel server  520  are illustrated as separate devices, it is also possible that these are combined in the same device. Also, actions at the user device  300  (client) can be performed via the application  350  executed thereon. The tunnel server  520  can be a proxy or transparent proxy. 
     The process  650  includes the client sending a trace packet for the destination (e.g., the node  150  with an address of a.b.c.d) with a Signature-A (step  651 ). Note, the client (e.g., the user device  300 ) does not know if there is a tunnel or not between the destination and itself. The purpose of the Signature-A is for any tunnel server  520  to detect this trace packet and provide tunnel details, i.e., to allow the client to detect the tunnel. The Signature-A can be any encrypted data for security. 
     The process  650  further includes the tunnel server detecting the Signature-A as a valid signature and intercepting the trace packet (step  652 ). In  FIG. 12 , even though the tunnel server  520  is not the destination, it intercepts the trace packet because of the presence of the Signature-A and responds. Namely, the tunnel server responds to the trace packet with tunnel info (step  653 ). The client receives the trace response from the tunnel server (instead of the destination) and is informed about the tunnel, and can take appropriate action (step  654 ). The tunnel info can include IP address, tunnel type, protocol, etc. As described herein, appropriate action includes determining a trace via different legs to account for the tunnel. Also, as described herein, a leg is a segment of the network between the client and the destination. Without a tunnel, there is a single leg between the client and the destination. With a tunnel, there is a plurality of legs with at least one leg being the tunnel itself. 
     If there is a transparent proxy present with an overlay tunnel to it from the client, the client sends traceroute probes with a signature to detect the presence of the proxy. When the packets traverse through the proxy, it scans for the signature in the payload, which can be encrypted using a shared key that can be rotated constantly. If the signature matches, the proxy identifies this as a probe generated by a trusted client and identifies itself as a proxy by responding to the probe with an encrypted signature. On receiving the probe response, the client would be able to identify the proxy in the path and request it to find the hops through the overlay tunnel. The request to the proxy can be performed out of band. 
     § 8.2 Collecting Network Details Including a Tunnel 
       FIG. 14  is a flowchart of a process  660  for collecting network details in a trace where there is an opaque tunnel. The process  660  is described with reference to the network in  FIG. 12  with actions at the user device  300 , the intermediate devices  600 ,  602 ,  604 , and the tunnel server  520 . Further, the process  660  can be used with the process  660 . Also, while described with reference to the enforcement node  150  as the destination, the process  660  contemplates operation with any type of computing device. Also, note that while the enforcement node  150  and the tunnel server  520  are illustrated as separate devices, it is also possible that these are combined in the same device. Also, actions at the user device  300  (client) can be performed via the application  350  executed thereon. 
     Once an opaque tunnel is detected, the process  660  is used to collect details of the service path between the client and the destination. The process  660  includes, responsive to detection of a tunnel, dividing the network from the client to the destination into a plurality of legs (step  661 ). A trace is performed separately on all of the plurality of legs (step  662 ), and the results of the trace on all of the plurality of legs are aggregated to provide a holistic view of the network (step  663 ). 
     The objective in segmenting the network into different legs is to provide visibility with the tunnel. Specifically, a trace is performed in the tunnel, such as via the tunnel server which is performing a so-called “reverse trace.” Here, the tunnel server is sending trace packets through the tunnel without tunnel encapsulation so that details of the trace can be obtained in the opaque tunnel. These details are combined with traces from the other legs to provide full visibility. 
     For the example of  FIG. 12 , once the client (user device  300 ) knows about tunnel, the network can be divided into three segments: 
     Leg-1: From the user device  300  to an egress router  630 , 
     Leg-2: From the tunnel client  510  to the tunnel server  520  (i.e., the opaque tunnel  610 ), and 
     Leg-3: From the tunnel server  520  to the destination (node  150 ). 
     For the Leg-1, the trace can be performed as normal. 
     For the Leg-2, the trace is performed between the egress router  630  and the tunnel server  520 . This is the reverse trace where the tunnel  610  is traced by the tunnel server. In an embodiment, the client, knowing there is an opaque tunnel based on the signature used in the process  650 , requests the tunnel server trace the tunnel. That is, the client sends a request for tracing by the tunnel server to the tunnel client, i.e., a reverse trace. The tunnel server performs the reverse trace, collects the results and forwards them to the client. 
     For the Leg-3, either the client can send a trace packet without the signature to trace the Leg-3 or the client can request the tunnel server perform a trace to the destination on its behalf. If the trace packet is sent from the client without the signature, the results will include details from Legs 1 and 2, which can be subtracted out since the results from Legs 1 and 2 are also separately obtained. Finally, the client can process all of the results from the three legs to present a holistic view of the network. Note, Leg-2 and Leg-3 go hand in hand—either you have both or none. If there is none, then the client only has one leg to the destination. 
     The foregoing assumes the tunnel client  510  is on the public Internet and reachable from the tunnel server  520 , i.e., the outside world can connect to the tunnel client  510 . However, most tunnel clients  510  are on an internal network behind a firewall, making it a problem for the tunnel server  520  to reverse trace to the tunnel client  510 . Thus, there are additional steps in this scenario. 
     Consider the issue of the tunnel client  510  being behind a firewall; there is a need to modify the network segments as follows: 
     Leg-1: From the user device  300  to an egress router  630 , 
     Leg-2: From the egress router  630  to the tunnel server  520 , and 
     Leg-3: From the tunnel server  520  to the destination. 
     As described herein, the egress router  630  is typically a router at an edge of a customer&#39;s network with a public IP address. The following describes the trace in each of these legs. For the Leg-3, the client can send the trace packet without the signature or request the tunnel server  520  to perform this leg on its behalf, i.e., the same as described above. 
     For the Leg-2, the following steps are needed, note these are as described above except the target is the egress router  630 . The tunnel server  520  is performing a reverse trace based on accepting a request from the client, but the reverse trace is from the tunnel server  520  to the egress router  630 . The tunnel server  520  provides the results to the client as before. 
     For the Leg-1, the client sends a trace packet to the egress router  630 . And as before, finally, the client aggregates all three legs to present a holistic view of the network. 
     For the Leg-1, there are two possibilities for what can happen to the trace packet from the client to the egress router. For a case-1, the tunnel client  510  can route the trace packet into the opaque tunnel  610 . For a case-2, the tunnel client  510  does not route the trace packet into the opaque tunnel  610 , i.e., bypasses it. For the case-2, this yields the trace to the egress router  630  data. However, for the case-1, this provides the wrong network path, namely from the client to the tunnel client  510  to the tunnel server  520  to the Internet to the egress router  630 . That is, the trace packet echoes from the tunnel server  520  providing the wrong network path. There is a need for the client to detect this wrong network path. 
     To detect the wrong path for the Leg-1, the client can be configured to insert another signature, Signature-B, in the trace packet for the egress router  630 . The objective is for the trace packet to reach the egress router  630  for a response. The purpose of this Signature-B is for the tunnel server  520  to detect it and provide a flag in the response. If the client gets a response to this trace packet with the flag therein, the client knows the trace went on the wrong network path, i.e., through the tunnel  610  to the tunnel server  520 . When this is detected, IT must reconfigure the tunnel client  510  to bypass the tunnel  610  for packets destined to the egress router  630 . Of note, the use of the terms Signature-A and Signature-B is solely meant to differentiate these as different signatures for different purposes. 
     As described herein, the present disclosure includes various traces of different legs of a service path, such as using MTR, and having the client (or another device) aggregate the results. Of note, while the illustrated example embodiments describe the traces in order, those skilled in the art will appreciate any order is contemplated. For example, in some embodiments, the traces of Leg 1 are performed first, then Leg 2, etc. In other embodiments, the traces of Leg 2 are performed first, etc. Finally, the traces may be performed concurrently or at about the same time. 
     In an embodiment, the tunnel client  510  can be a tunnel originating from the application  350  and the egress router  630  can represent the public facing side of the network from where location tunnels (GRE/IPSEC) will originate. Most cases will have the user device  300  on a private IP talking to the outside world via a router or a Wi-Fi Access Point (AP) that is connected to an egress router  630  that has a public IP. The case of a tunnel client  510  having a public IP is rare and could happen when there is a device on cellular network. From the point of the enforcement node  150 , it always traces the Leg 2 path from itself to the public IP the client comes out with. It does not care if it is an egress router or a tunnel-client end point that is on the public IP. 
     § 8.3 Example Operation 
       FIG. 15  is a flow diagram illustrating actions between the client (user device  300 ), the tunnel client  510 , the egress router  630 , the tunnel server  520 , and the destination  640  in an example operation of the processes  650 ,  660 . Note, the processes  650 ,  660  can be orchestrated by the user device  300  (client) via the application  350 . The client sends a trace packet to the destination with the Signature-A as described in the process  650 . If the response comes back with no tunnel info in the response, then the full and accurate service path has been traced and the trace is complete. If there is tunnel info, the client knows there is the tunnel  610  and moves to the process  620 . 
     In order to collect a full network path, first the client needs to detect if there is a tunnel on the path. Again, this is achieved by the client inserting a signature in a packet. The packet is intercepted by the tunnel server  520  and it will respond with tunnel information like type, IP, etc. Once the client notices the tunnel on the path, it will run the multi-segment approach in the process  660  to detect the full service path. 
     Next, the client fetches the egress IP using the restful API. The client assumes three network segments—Leg-1: Client to Egress, Leg-2: Egress to Tunnel Server, and Leg-3: Tunnel Server to Destination. The client performs the trace of the Leg-3 either directly or by requesting the tunnel server to perform it and collect information. The client performs the trace of Leg-2 by requesting the tunnel server perform the reverse trace. The client also sends a trace packet to the egress router  630  with the Signature-B. If there is no tunnel flag in the response, the client has the full and accurate Leg-1 information. If there is the tunnel flag in the response, there is a misconfiguration presented to the user. 
     Finally, the client aggregates all three legs and consumes the data. The tunnel server  520  can host a tracing service that will accept tracing requests from clients such as via a restful API call, an HTTP Post call, etc. This service will perform standard network tracing, collect the data and respond to clients. The resultant data can be displayed and used in different ways. 
     § 9.0 Detection of Network Hops and Latency Through an Opaque Tunnel and Detection Misconfiguration of Tunnels 
       FIG. 16  is a flowchart of a process  670  for detection of network hops and latency through an opaque tunnel and detection misconfiguration of tunnels. The process  670  is described with reference to the user device  300 , i.e., the client. The process  670  can be implemented as a method that includes steps, via the user device  300  configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  670  includes requesting a trace to a destination with a signature inserted into a trace packet (step  671 ); receiving a response to the trace packet (step  672 ); when the response does not include tunnel info, providing details in the response to a service where the details include parameters associated with a service path between the client and the destination (step  673 ); and when the response includes tunnel info, segmenting the service path into a plurality of legs, causing a trace for each of the plurality of legs, and aggregating details for each of the plurality of legs based on the causing (step  674 ). 
     When the response includes tunnel info, a tunnel server is configured to intercept the trace packet responsive to detection of the signature, and wherein the tunnel server responds to the trace packet with the response with the tunnel info. The aggregating details includes aggregating network hops, packet drops, and latency for each of the plurality of legs. The plurality of legs can include three legs. In an embodiment, a first leg is between the client and a tunnel client, a second leg is between the tunnel client and a tunnel server, and a third leg is between the tunnel server and the destination. In another embodiment, a first leg is between the client and an egress router, a second leg is between the egress router and a tunnel server, and a third leg is between the tunnel server and the destination. 
     The causing the trace for the plurality of legs can further include including a second signature in a second trace packet to an egress router, and the process  670  can further include receiving a response from the second trace packet; when the response does not include a flag, utilizing details from the response for a leg between the client and the egress router; and when the response includes the flag, determining a misconfiguration where the second trace packet was sent over a tunnel. At least one of the plurality of legs can include a reverse trace from a tunnel server. The tunnel info can include a type of tunnel including any of Generic Routing Encapsulation (GRE) and Internet Protocol (IP) Security (IPsec). 
     The process  670  helps detect the network hops, packet drops, and their latencies through tunnels like the GRE/IPsec or any other overlay tunnel. A typical network analyzer will not be able to find the hops, packet drops and their latency through individual routers that constitute the overlay tunnel as the probe traffic is encapsulated through the tunnel and the whole tunnel looks like a single hop. The process  670  enables a trace of the hops through the tunnel thus giving an insight into the hops inside the tunnel. The tracing of the path is done by initiating the probes from the other side of the tunnel without encapsulating the packet, i.e., from the a destination  640  towards the client which is called as “Reverse Traceroute” as described herein. This also helps detect if the overlay tunnels are correctly configured so that traffic bound to the internal network is not pulled into the tunnel. 
     § 10.0 Detection of Latency, Packet Drops, and Network Hops through a TCP Tunnel using ICMP and UDP Probes 
     In another embodiment, the tunnel can include a TCP connection, i.e., a TCP-based tunnel or an exclusive TCP overlay tunnel. The present disclosure can trace this path to detect statistics such as hops, packet drops, and latency through the exclusive TCP overlay tunnel using ICMP and UDP traffic. This approach leverages the approach in the process  670  to find the hops through the tunnel using a protocol other than TCP for which the tunnel was built. This approach uses the routing in the opposite direction as the enforcement of the TCP check made at the end of the tunnel that the client owns. The destination  640  sends probes from its side of the tunnel without using any tunnel encapsulation towards the client&#39;s egress router&#39;s IP. 
     Advantageously, this approach avoids using TCP-PINGs (use of TCP SYNs) from the client side towards the destination to avoid cases where firewall rules would flag issues thinking of it as an attack. 
       FIG. 17  is a flowchart of a process  680  for detection of latency, packet drops, and network hops through a TCP tunnel using ICMP and UDP probes. The process  680  is described with reference to the destination  640 . The process  680  can be implemented as a method that includes steps, via the server  200  configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  680  includes receiving a request from a client to perform a reverse trace (step  681 ); requesting a trace to an endpoint that is one of an egress router and a tunnel client, wherein there is a tunnel between i) the destination and ii) the one of the egress router and the tunnel client (step  682 ); receiving a response to the trace (step  683 ); and sending details associated with the response to the client so that the client aggregates these details with details from one or more additional legs to provide an overall view of a service path between the client and the destination (step  684 ). 
     The process  680  can further include receiving a trace packet from the client with a signature included therein, wherein the signature is indicative of a request for tunnel info; and, responsive to detection of the signature, sending the tunnel info to the client in a response. The process  680  can further include receiving a trace packet from the client with a signature included therein, wherein the signature is indicative of a misconfiguration of a tunnel; and, responsive to detection of the signature, sending a flag to the client in a response indicative of the misconfiguration. 
     The destination can be one of a tunnel server and a node in a cloud-based system. The tunnel can utilize Transmission Control Protocol (TCP) and the trace to the endpoint utilizes a packet without tunnel encapsulation. The packet can utilize one of Internet Control Message Protocol (ICMP) and User Datagram Protocol (UDP). The request can be via a RESTful (Representational State Transfer) Application Programming Interface (API) call from the client. 
     § 11.0 Detection of Latency, Packet Drops, and Network Hops Through a Tunnel by Tracing Hops Herein 
     As described above, the tunnel  610  is an opaque overlay making it difficult to trace. The aforementioned approaches contemplate a reverse trace via unencapsulated packets. In an embodiment, the tunnel itself may be configured to perform the trace, such as via the cloud tunnel  500 . There are two techniques the tunnel  500  can use to perform the trace inside the tunnel. 
     In a first approach, the tunnel  500  can be configured to identify probe traffic based on a predefined signature and inherits the IP TTL value of the probe packet. Note, as described herein, probe or probe traffic means trace packets. As the packet makes its way through the tunnel the packet&#39;s TTL would expire triggering an ICMP “Time Exceeded” error. This error is propagated by the tunnel to the probe initiator (such as the client) spoofing the IP address of the router that generated the error. 
     In a second approach, the tunnel  500  itself can initiate trace probes towards the other end of the tunnel  500  by increasing the TTL in the packets by one at a time. By tracing the path to the other end of the tunnel  500 , the exact number of hops, packet drops, and latency inside the tunnel  500  is determined. This information can be provided to any of the clients/applications via an API so that they know the measure of these stats that can be combined with the other trace stats to get a complete picture of the path the packet traverses. This measurement can be initiated from both sides of the tunnel  500  to gauge any changes in routing due to asymmetric routing. 
       FIG. 18  is a flowchart of a process  690  for detection of latency, packet drops, and network hops through a tunnel by tracing hops therein. The process  690  is described with reference to a node associated with the tunnel  500 , i.e., either the tunnel client  510 , the tunnel server  520 , or the egress router  630 . The process  690  can be implemented as a method that includes steps, via a processing device configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  690  includes receiving a request for a trace of the tunnel from a client (step  691 ); causing the trace inside the tunnel (step  692 ); obtaining results of the trace inside the tunnel (step  693 ); and sending the results of the trace inside the tunnel to the client so that the client aggregates these details with details from one or more additional legs to provide an overall view of a service path between the client and a destination (step  694 ). 
     The inside the tunnel can include identifying a packet with a predefined signature, analyzing a Time-to-Live (TTL) value in the packet, and sending a response to a probe initiator based on the TTL value. The response can include an Internet Protocol (IP) address that was spoofed based on a router where the TTL value expired. 
     The trace inside the tunnel can include sending trace packets to another end of the tunnel each having increasing Time-to-Live (TTL) values. The trace packets can be sent from both ends of the tunnel to determine any changes in routing between directions. 
     The tunnel can include a data channel and a control channel each having different encryption. The encryption can be any of Transport Layer Security (TLS), Secure Sockets Layer (SSL), and Datagram Transport Layer Security (DTLS). 
     § 12.0 Metric Computation for Trace Probes using Cached Data to Prevent a Surge on Destination Servers 
       FIG. 19  is a network diagram illustrating a user  102  connected to an enforcement node  150  in a digital experience monitoring application. In a practical embodiment, the cloud-based system  100  with the nodes  150  as proxies can be used to perform digital experience monitoring as described herein. In such as system, there can be a lot of probes. To prevent a surge of traffic to the destination  640 , the present disclosure includes a cache approach where trace results are cached on the proxy for a finite configurable time. For that time interval, all subsequent probe requests are served out of the cache rather than sending a new set of probes per request. While one request is pending on a destination  640 , any probe that arrives for the same destination can be held in a queue and responded from the cache when the response for the first probe arrives and is cached. 
     Specifically, if a lot of user devices  300  with the applications  350  are independently probing the destination  640  there is a risk of throttling of the probes at the destination  640  and the hops as well as blacklisting IP addresses of the tunnel server  520  or nodes  150  used to probe the destination  640 . 
     The enforcement node  150  is configured to probe the destination  640 , i.e., the leg  3 , on behalf of requesting clients. The enforcement node  150  is also configured to probe the tunnel  500 ,  610  as described herein, i.e., leg 2, in a reverse trace. The present disclosure contemplates the enforcement node  150  caching results from these two legs and serving subsequent requests from the cache for a predetermined amount of time. Each cache entry can include all hop IP addresses from the enforcement node  150  to the destination  640  and from the enforcement node  150  to the egress router  630 , packet loss, and latency for each probe sent. Note, some clients can share both legs 2 and 3 whereas some clients may have a different leg 2 or 3. Those skilled in the art will recognize either or both can be served out of cache as required. 
       FIG. 20  is a flow diagram illustrating actions between the client (user device  300 ), the application  350 , the egress router  630 , the enforcement node  150 , and the destination  640  in an example operation of the processes  650 ,  660 , along with caching of trace results at the enforcement node  150 . In this example, the application  350  is the tunnel client  510  whereas the enforcement node  150  is the tunnel server  520 . The flow includes client configuration via the application  350  including the cloud tunnel  500 . The application  350  can send an ICMP traceroute to the destination  640  IP address with the Signature-A in the ICMP payload. The enforcement node  150  is configured to terminate the ICMP traceroute and send an ICMP response by faking the destination IP as the source along with tunnel info in the ICMP payload. Once the application  350  is aware of the tunnel, the application  350  can send a trace API request, create an SSL connection with the enforcement node  150  and send a POST request to the tunnel service at the enforcement node  150  with details in a JavaScript Object Notation (JSON) body. The application  350  can send a restful MTR request to enforcement node  150  which includes the destination address and port in case of TCP/UDP MTR. It should also include the MTR type: TCP, UDP or ICMP. The various signatures can be via a Type-Length-Value (TLV) in the ICMP request and reply. 
     The enforcement node  150  is configured to perform the reverse trace of Leg 2 and the trace of Leg 3. The enforcement node  150  maintains the results of these two Legs 2, 3 in a cache for a predetermined amount of time, e.g., one minute or some other configurable value. If the results are not in the cache, the enforcement node  150  performs the trace, e.g., using MTR. The enforcement node  150  can combine the results which include latency, packet loss, and hop information and send this via a trace POST API response to the application  350 . 
     The application  350  performs an ICMP traceroute to the enforcement node  150  outside of the tunnel  500 . The application  350  can determine or compute the Leg 1 results based on subtracting the Leg 2 results from the results of this ICMP traceroute to the enforcement node  150  outside of the tunnel  500 . Of course, this can be other types of traces. 
       FIG. 21  is a flowchart of a process  700  for metric computation for trace probes using cached data to prevent a surge on destination servers. The process  700  is described with reference to one of the enforcement nodes  150  associated with the cloud-based system  100 . The process  700  can be implemented as a method that includes steps, via the enforcement node  150  configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  700  includes receiving a request, from a client, for one or more of a first trace of a tunnel and a second trace to a destination (step  701 ); checking a cache at the node for results from previous traces of the first trace and the second trace (step  702 ); responsive to the results not being in the cache, performing one or more of the first trace and the second trace (step  703 ); and providing the results to the client so that the client aggregates the results with details from one or more additional legs to provide an overall view of a service path between the client and the destination (step  704 ). 
     The process  700  can further include, subsequent to the performing, storing corresponding results in the cache. The process  700  can further include, subsequent to a predetermined time period, removing the results from the cache. The process  700  can further include receiving a trace packet from the client outside of the tunnel; and providing a response to the trace packet, wherein the client utilizes details in the response in addition to the first trace and the second trace to determine details of the service path. The process  700  can further include receiving a trace packet to the destination from the client with a signature therein; and terminating the trace packet and responding thereto with the destination&#39;s address and with details about the tunnel. The client can connect to the destination through at least three legs. The providing can include at least one of the first trace and the second trace from the cache and the other from the performing. 
     § 13.0 TCP Traceroute using RST and SYN-ACK to Determine Destination Reachability 
     Referring back to  FIG. 11 , for a description of a TCP traceroute from the client (user device  300 ) to the destination (node  150 ), the client creates a series of packets with increasing TTL values. TTL values are decremented for each hop. When each packet is received at the routers  602 A- 602 D with the TTL value of  0 , the packet is discarded, and a response is sent back to the client (“TTL Time Exceeded”). The response includes information regarding its location and indicating data transfer times. Finally, the client knows that the destination has been reached (and stops sending packets) when it receives a different message from a hop, saying that the port intended is unreachable (“Destination/Port unreachable”). In order to use TCP for tracing the path to the destination, one cannot use standard TCP stream sockets as internally TCP always retransmits packets, and, as a result, one cannot estimate the packet loss and latency sitting at the application layer. To avoid this, traceroute (aka TR) applications use raw sockets where TCP packets are framed in the application and directly injected into the network bypassing the TCP stack. 
     Current TCP traceroute applications/tools cannot determine if the destination has been reached as they have no ability to read the response sent by the destination. In an embodiment, the present disclosure includes determining the reachability of the destination by peeking into the response packets for a SYN-ACK or an RST sent by the destination. A reception of the SYN-ACK or RST from the destination will indicate the availability of the destination. This ability to peek into the TCP stack for a response is unique and gives the ability to use TCP as a technique to determine reachability. 
     ICMP and UDP TR implementations detect the destination reachability by looking at “ICMP ECHO” response and “UDP port unreachable” errors, respectively. This is relatively straightforward as the responses from the intermediate hops and the destination are at the ICMP layer which the applications can snoop and process. 
     TCP poses a unique challenge in that the final destination responds with either an RST or a SYN-ACK when the TCP SYN hits the destination stack. These responses generated by the destination are not ICMP responses but instead are standard TCP responses that the local TCP stacks on the originator of the request consume. So while the request packet was injected by a raw socket, the TCP RST or the SYN-ACK would land up on the TCP stack and as there is no corresponding TCP socket, the response from the destination is silently dropped believing its a stray. As a result of this, TCP traceroute applications will not be able to detect the responses from the destination thus rendering the utility with very little use as the path is always incomplete with no destination ever discovered. 
     To address the lack of reachability detection of the destination, the present disclosure includes a modification to the TCP stack to recognize TCP traceroute traffic and divert the RST/SYN-ACK response to appropriate “raw sockets” so that the TR application can determine the reachability to the destination. This way the TCP TR can draw the complete path with all the intermediate hops and the final destination giving the administrator a full picture of the path taken by a packet from the source to the destination. Also, the raw RST packet can be sent to the destination as well after SYN-ACK is received by a TR application so that the connection can be closed in time rather than waiting for a timeout. As described herein, a TR or traceroute application is software executed on a processing device such as the server  200  or the user device  300  for implementing a traceroute, such as using TCP traceroute. Also, TCP checksum, sequence, and ACK in the RST packet are handled by TR application itself. The source port in the SYN packet is allocated by TCP stack from the port pool based on destination IP and port to avoid collision with real user traffic. 
       FIG. 22  is a flowchart of a process  710  for TCP traceroute using RST and SYN-ACK to determine destination reachability. The process  710  is described with reference to one of the user device  300  with the application  350  and the enforcement nodes  150  associated with the cloud-based system  100 . The process  710  can be implemented as a method that includes steps, via a processing device configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. The process  710  can be implemented via a trace application implementing a TCP stack in the processing device. 
     The process  710  includes sending a plurality of TCP packets via a raw socket to perform a trace to a destination (step  711 ); receiving responses to the plurality of TCP packets (step  712 ); detecting the responses in the TCP stack and diverting the responses to the raw socket (step  713 ); and aggregating the responses by the trace application to determine details of a service path from the processing device to the destination (step  714 ). 
     The plurality of TCP packets can include TCP Synchronize (SYN) messages, and the responses include TCP SYN-Acknowledgement (ACK) or Reset (RST) messages. The process  710  receiving a TCP SYN-ACK message from the destination; and sending a TCP RST packet to the destination. A TCP checksum, sequence, and ACK in the TCP RST packet can be implemented by the trace application. The raw socket can be used in lieu of a TCP socket. A port for the raw socket can be allocated by the TCP stack from a pool of ports based on the destination. 
     § 14.0 Adaptive Probing to Discover a Protocol for Network Tracing 
     Traceroute implementations conventionally use just one protocol to trace the path from the source to the destination along with the hops, latency, and packet loss stats. In an embodiment, the present disclosure includes a combination of ICMP, UDP and TCP to get a more accurate measurements of hops, packet loss, and latency from source to destination. As each network entity tends to respond to a particular protocol more favorably, the present disclosure uses the protocol that would have the highest probability of getting a response. Results from using different protocols are aggregated and displayed as one. A problem with traceroute is that it relies on hosts responding with ICMP errors for TTL expiry which is unreliable due to routers either disabling this or rate limiting. Note, routers that run BGP respond to TCP port 179 while blocking ICMP. 
     The following utilizes the example of  FIG. 19  with the three legs, namely Leg 1, Leg 2, and Leg 3. In an embodiment, a single protocol—ICMP/UDP/TCP—is used to probe all three legs. Using ICMP/UDP for Leg 3 is not advisable as the probes are primarily to check the availability of a destination  640  that is a Web app which is running on TCP ports 80/443. For example, a particular Web app can be 100% available but show a path to the destination that is broken, with the reason being that ICMP and UDP probes are blocked by the destination  640 . 
     The present disclosure includes a dynamic probe that tries a combination of protocol types to get an estimate of packet loss and the latency to the egress/destination. Determining the intermediate hops and their latency/packet loss is a matter of luck irrespective of the protocol used as the TTL expiry is a Layer 3 property handled by routers. For practical purposes, the choice of protocol is significant inside a customer network due to Access Control List (ACL)/Firewall (FW) rules while less significant on the internet although some routers prioritize TCP traffic over the rest. The choice of protocol is the most significant when the end host receives it as the response to the probe is completely dependent on the rules configured on that host and these are all over the place. 
     Most destinations  640  will only respond to TCP ports 80/443. The egress routers  630  will respond to ICMP-ECHO at times and could either respond with a SYN-ACK or RST when a TCP probe is sent to port 179/80/443. There are only two entities that are guaranteed to respond and metrics to these can be trusted, and the rest are best effort. The two entities include the destination  640  responding to a TCP SYN on port 443 (assuming Web apps), and the node  150  responding to a PING or TCP SYN. 
     In an embodiment, the destination  640  is a SaaS endpoint running Web applications. With a TCP SYN to port 443 on the destination  640 , the destination  640  is bound to respond with a true measure of reachability, latency and packet loss. Assume that this will be the IP of the load balancer fronting a server farm for the destination  640  but then that is how far the service path can be reached. It is also possible to close the connection to the server with an RST/FIN to free up any resource on the destination  640 . Packet loss and latency to the destination  640  are determined by the response to the TCP SYN. One optimization to find the latency and packet loss could be to harvest the data for the domain from the web probes. But it is still necessary to send the TCP traceroute probes to determine the number of hops to the destination  640 . 
       FIG. 23  is a network diagram with an excerpt of the network diagram of  FIG. 19  illustrating Legs 2 and 3 for illustrating adaptive probing. In an embodiment, the egress router  630  is probed from two sides—from the application  350  and from the enforcement node  150 . The approach is to first find a protocol the egress router  630  will respond to by sending a set of probes directly to the egress router  630  by setting a large TTL and then employing the regular MTR logic to trace the hops in between. This way it is known that there is a point at which the probes will get a response. 
     To give an example, start with ICMP-ECHO to the egress router  630  IP with TTL=64, if there is no response, then switch to TCP-SYN probes to ports 179 (Border Gateway Protocol (BGP)), 80, 443. Either an RST or an SYN-ACK will give the latency and the packet loss. 
     § 14.1 Detecting Packet Loss between the Application and the Egress Router 
     There are two parameters to check here—packet loss and latency. In an embodiment, once the egress router  630  IP address is determined, ICMP/UDP probes are sent towards the egress IP with the hope that it responds. The issue with this is that if the egress router  630  is configured to drop ICMP/UDP probes then it will show as unreachable. 
     With respect to packet loss detection, as the handling of the ICMP responses to TTL expiry are done in software and rate limited, the lack of an ICMP error response is not a measure of the packet loss at that hop. Also, the egress routers on the customer network might have ICMP turned off or rate limited. But if the packets are being forwarded by the egress router  630  then that is a good measure of its ability to handle load and also routers are rated based on their ability to forward packets which is mostly done in hardware. 
     The following describe techniques to gauge packet loss when the egress router  630  is configured to drop or rate limit packets. 
     In a first step, the approach tries to reach the egress router  630  by using ICMP followed by UDP and TCP and checks for packet loss. This does not need to be a configured number of probe, e.g., it can be three probes to see if the egress router  630  responds. Based on the response to a protocol, this is stored for future reference. For example, send three ICMP probes and wait for a response. If they all fail, then send three UDP problems, and if they all fail, then send three TCP probes. 
     In a second step, if the result of the first step is not 0% packet loss or an acceptable %, the second step includes trying to reach beyond the egress router  630  to get a response. The intent is to exercise the packet forwarding path of the egress router  630  versus the software handling of the packets. If the packets could be forwarded successfully, then its implied that there is no loss. A safe reference point can be the enforcement node  150  as the IP address. There are two possibilities—approach 1—use the tunnel  500 ,  610 , or approach 2—outside the tunnel  500 ,  610 . 
     In a third step, when the results of the first step and the second step are not acceptable, pick a last router in the customer&#39;s network with a private IP that is responding. The egress router  630  is the first public IP address that is encountered. For the last router, looking at the routing of packets, it is the egress router  630  with one leg in the private network and the other in the public that will move the packet out of the customer premise. There could be an independent Network Address Translation (NAT) device before the egress router  630  for NAT&#39;ing the IP but even reaching that could be a fair approximation of the loss. 
     The above steps are performed by the application  350  and it can maintain a cache with the approach and the results that may be refreshed periodically, when a network change occurs, and/or when the results are not good. As TCP-SYN seems to be the best bet given the rate limiting logic for ICMP on most devices, it is possible to a firewall that might see too many SYNs going out, and caching seems the best way to avoid raising a False Alarm on the firewalls and for them making changes on the firewall to let the probes out. 
     § 14.2 Detecting Packet Loss between the Enforcement Node and the Egress Router 
     Note that a majority of the IT administrators disable their egress routers  630  to respond to any form of traffic destined to their IP on the Internet facing side. Based on experimentation, with ˜7000 egress outer IP addresses, only 39% responded. In a first approach, the packet loss can be measurement outside of the tunnel  500 ,  610 . Here, the application  350  can send a configured number of probes (e.g., ICMP, TCP) to the enforcement node  150 , e.g., 11 TCP-SYN probes with TTL=64. That is, in this first approach, the assumption is packet loss between the enforcement node  150  and the egress router  630  is the same as the packet loss between the user device  300  and the enforcement node  150 . If the packet loss is zero or acceptable, this is a safe assumption. 
     In a second approach, the enforcement node  150  can try to direct a trace to the egress router  630 . This second approach can be performed if the packet loss from the first approach is not acceptable. In an embodiment, this can include sending a set number of ICMP probes destined to the egress router IP. If the response is obtained, then ICMP works other probes can be sent to the egress router  630  to measure latency and packet loss. If the ICMP probes fail, then TCP SYN probes can be sent to port 179/80/443 hoping to get a SYN-ACK or RST. Otherwise, UDP probes are sent to the trace ports. Any result can be one or a combination of the first approach and the second approach. 
     § 14.3 Detecting Latency from Application and Node to the Egress Router 
     If the egress router  630  responds, then the latency is known. The problem is when the egress router  630  does not and there is still a need to estimate the latency. When switching between the ICMP, the TCP, and the UDP probes to judge the latency to the egress, if the egress router  630  does not respond, the following is performed to infer the latency. 
     With reference to  FIG. 23 , it is possible to determine the latency from the application  350  to the node  150  as the node  150 &#39;s IP responds to pings and TCP SYN. The latency from the application  350  to the egress router  630  is called ‘A’ and the latency from the enforcement node  150  to the egress router  630  is called ‘B.’ If either A or B can be measured, the other one can be derived and, as long as it is a positive value, it can be used as a fair estimate. That is C=A+B, C being the latency from the client to the enforcement node  150 . In the worst case, if the egress router  630  was not reachable from either side, then take ‘A’ as the time it takes for the application  350  to reach the farthest router (private IP) on the Intranet. If needed, it is possible to take the time the first public IP took to respond and the time it took to reach the farthest router on the Intranet and average their times. 
     The reverse trace can be avoided when there is no opaque tunnel present. Here, the application  350  can trace the path from itself to the enforcement node  150  using ICMP or TCP pings. Due to the absence of the opaque tunnel, the tracero trace ute probes from the application  350  will be able to trace its path to the enforcement node  150 . 
     For the purpose of calculating the latency when the application  350  is not able to reach the egress router  630 , it is possible to have the enforcement node  150  to PING/TCP-PING to the egress router  630  to get latency. The enforcement node  150  does not have to do the trace but just needs to get the Round Trip Time (RTT) to the egress router  630  so that it is possible to compute A=C−B. 
     § 14.4 Comparing ICMP and TCP PING Data 
     It was evaluated as to whether ICMP and TCP probes take different paths on the Internet. It was determined that TCP and ICMP packets are routed along the same path on the Internet when we consider the network as an Autonomous System (AS). This was based on a 122k set of hops and it was found that PING and TCP probes took the same path and never deviated even once when looking at it from an ASN angle. 
     § 14.5 Adaptive Probe Process 
       FIG. 24  is a flowchart of an adaptive probe process  720  for trace probes. The process  720  is described with reference to one of the user device  300  with the application  350  and the enforcement nodes  150  associated with the cloud-based system  100 . The process  720  can be implemented as a method that includes steps, via a processing device configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  720  includes, for one or more legs of the plurality of legs, sending a number of probes using one of a plurality of protocols (step  721 ); responsive to receiving a response from the number of probes, determining the one of the plurality of protocols is successful and storing this protocol the one or more legs (step  722 ); and, responsive to failure to receive the response, sending a number of probes using another one of the plurality of protocols and continuing until a successful protocol is determined or all of the plurality of protocols fail (step  723 ). 
     The plurality of protocols can include Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), and User Datagram Protocol (UDP). The plurality of legs can include a first leg, a second leg, and a third leg. The third leg can be to a destination that includes a Web application, and wherein a protocol for the third leg includes Transmission Control Protocol (TCP). At least one of the first leg, the second leg, and the third leg can include a different protocol used thereon. Packet loss and/or latency between the first leg and the second leg can be determined based on a single trace therebetween. The process  720  can further include aggregating results for all of the plurality of legs, wherein at least two of the plurality of legs used a different protocol from one another. 
     § 15.0 Accurate Differential Trace Latency Calculation between Hops 
     Again, trace is a diagnostic command to find the routes (paths) and measures the latency to each hop. In a trace, each node-to-node connection is called a hop and the latency is the round trip from the user&#39;s machine to the destination. 
     The conventional traceroute has limitations that it might not be complete, and the results are not accurate for the final hop as the final hop does not provide the processing delay. The traceroute results might not be complete as the final destination might not respond to the probe. The conventional traceroute does not provide the latency between the hops. Routers typically have a very fast forward path as this is done in the hardware, but some routers take significant time to respond to TTL expired messages as they do this through software. 
     In an embodiment, trace enhancements are provided that provide accurate calculations when the traffic goes through the enforcement node  150  as well as provides the latency between hops. When a customer uses the cloud-based system  100 , the traffic from the user device  300  is sent through the enforcement nodes  150 . The trace is used to provide the latency from the user device  300  to the egress router  630  as well to the enforcement node  150 . If a site is bypassed in the cloud-based system  100 , the trace measures the latency from the user device  300  to the site. 
     The edge connector  150 A can be configured to combines this trace information with the information from the enforcement node  150  and provide the measurements to the user. The enforcement node  150  provides the trace measures from enforcement node  150  to the destination  640 . Both the enforcement nodes  150  and the edge connector  150 A cab support ICMP, TCP, and UDP protocols for traceroute. 
     When traffic is going through the enforcement node  150 , the edge connector  150 A can perform the trace using the enforcement node  150 ′s IP address. The enforcement node  150  is configured to always respond to the trace probe from the edge connector  150 A. This solves the incompleteness problem for the conventional traceroute that can happen in the trace that some destinations might not respond to the probe. If the destination  640  is bypassed in the cloud-based system  100 , the edge connector  150 A does tracing to the destination  640 , for a best effort latency measurement to the final destination as the final destinations did not provide the processing delay. If the final destination did not respond, it provides the information for all other hops. 
     When the enforcement node  150  receives this probe, it responds back providing the packet processing delay in the data payload. This provides accurate absolute latency to the enforcement node  150 . If the destination is bypassed in the Zscaler cloud, the Zscaler Edge connector does the best effort latency measurement to the final destination as the final destinations do not provide the processing delay. 
     § 15.1 Latency between Hops 
     The edge connector  150 A sends a configured number of packets to hops starting with TTL  1  to the maximum configured TTL to the enforcement node  150 . The hops, which are configured to respond, send the response and the edge connector  150 A measures of the round-trip latency for the packet to these hops. 
     The edge connector  150 A uses the results from all the routers  602  as well the enforcement node  150  to calculate the latency difference between hops. The edge connector  150 A uses the average latency for a hop and uses that to compute adjusted averages and the difference is computed between adjusted averages. 
     § 15.2 Average Latency 
       FIG. 25  is a network diagram of a network for illustrating an average latency calculation. This section describes how the average latency is calculated. In this example, there is the user device  300  connected to the destination  640  via four intermediate routers  602 - 1  to  602 - 4 .  FIG. 26  is a diagram of the network of  FIG. 25  illustrating an operation. When a router/destination does not respond to ICMP/UDP/TCP traceroute probe, the value is recorded as −1. The average (AVG) is the sum of all positive values divided by the positive value count. If the hop is not responding, its average latency is set to 0. 
     The following describes how the average phase is adjusted. The average latency for each hop is copied to the adjusted average. The end is the last hop and the start is the first hop. 
     Step S1: Set index=end where end is the last value. 
     Step S2: Set current to end−1. 
     Step S3: If current==start−1, Go to step 9. 
     Step S4: If the hop at the current is not responding, set current=current−1. Go to Step S3. 
     Step S5: If the average latency of the current is more than the adjusted average of the index, then set the adjusted average of the current to the adjusted average of the index. If the average latency for the current is lesser than or equal to the adjusted average of the index, then do not change. 
     Step S6: Set index=current. 
     Step S7: Current=current−1. 
     Step S8: Go to step S3. 
     Step S9: Exit. 
       FIGS. 27-30  illustrate an example operation of the average latency adjustment. 
     § 15.3 Differential Average Latency 
     If there is only one hop, the edge connector  150 A can set the differential average to its average. The following describes a differential phase computation. 
     Step S11: Set index=first responding hop. 
     Step S12: Set current=index+1. 
     Step S 13 : If current=end+1, Go to step S19. 
     Step S14: If the hop at “current’ is non-responding hop, set current=current+1. Go to step S13. 
     Step S15: Compute differential average for the hop at current=adjusted average of hop at current−adjusted average of the hop at index. 
     Step S16: index=current. 
     Step S17: current=current+1. 
     Step S18: Go to step 13. 
     Step S19: Exit. 
       FIGS. 31-34  illustrate an example operation of the differential average latency adjustment. This shows that average round trip latency is  14 ms from the user device  300  to router  602 - 1 . The average latency between routers  602 - 1 ,  602 - 2  is &lt;1 ms. The average latency between  602 - 2 ,  602 - 3  is 1 ms. The average latency between the routers  602 - 3 ,  602 - 4  is 2 ms. 
     § 15.4 Process for Accurate Differential Traceroute Latency Calculation between Hops 
       FIG. 35  is a flowchart of a process  750  for an accurate differential traceroute latency calculation between hops. The process  750  is described with reference to one of the user device  300  with the application  350  and the enforcement nodes  150  associated with the cloud-based system  100 . The process  750  can be implemented as a method that includes steps, via a processing device configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  750  includes performing a plurality of traces between two nodes in a service path (step  751 ); obtaining latency measurements for each of the plurality of traces for each of one or more hops between the two nodes (step  752 ); and determining average latency between each of the one or more hops based on the latency measurements, adjusted average latency for each hop, and differential average latency for each hop (step  753 ). The nodes can include two nodes in a cloud-based system. A first node is an enforcement node  150  and a second node is an edge connector  150 A. The plurality of traces utilize either Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), User Datagram Protocol (UDP), or a combination thereof. A destination of the plurality of traces can be a node in a cloud-based system. 
     § 16.0 Adaptive Tracing, aka “CloudPath” 
     The present disclosure includes an approach, using the cloud-based system  100  and the user device  300 , for adaptively finding the protocol that works best for the internal network and the destination  640 . This approach can be implemented in a software module that detects the best protocol (e.g., TCP, UDP, ICMP, etc.) by checking which protocol could reach the destination and which protocol provides the result by checking which protocol provides Least Average latency, Least Average Loss, and Number of Hops found. The module can be implemented in the user device  300 , communicating to the cloud-based system  100 . 
     In this approach, egress means the exit of the network and the destination means the final target for the trace. The application  350  is able to identify the Client egress through the REST API call that the client connector makes the to one of the enforcement nodes  150 . 
     Trace policy is provided from the cloud-based system  100 . The policy specifies a starting hop, ending hop, protocols to be used for egress and destination, number of packets to send, delay between the packets, UDP and TCP ports for egress and destination, destination domain or IP, intervals to be used by the application  350 , and the default protocol to used for egress and destination in case of failure. The policy also specifies the detection technique—least latency, least loss, or the number of hops found, that can be used to find the best protocol for the target. 
     § 16.1 Automatic Operation 
     The adaptive protocol module runs without manual intervention when there is an egress change or a gateway IP change on the user device  300  or at the configured interval if there is no change in the egress and gateway. The module runs before the actual trace to find the best protocol to the destination, through traces performed in the different protocols for the purpose of finding the best results. The module then finds the protocol to use and then performs the actual trace using the protocol. The adaptive protocol module can be part of the application  350  on the user device as well as in one of the nodes  150 . That is, the techniques described herein can be performed at the user device  300  and at the node  150 . 
     § 16.2 Adaptive Protocol Detection for the Internal Network 
     The module can detect the egress through a call to one of the nodes  150  in the cloud-based system  100  which can provide the egress IP. The adaptive trace module finds the best protocol to use for the trace to the egress by sending probes using TCP, UDP, and ICMP protocol. The detection is triggered on egress or a gateway change or at the end of the configured interval if there is no change in egress or gateway. The module checks which protocol can reach the egress IP by doing a trace to the Egress IP. The module detects the best protocol by checking which protocol could reach the egress, evaluating least latency, least loss, and/or the number of hops found. 
     For example, this protocol detection step can include sending trace probes using different protocols to the egress IP, e.g., TCP, UDP, and ICMP protocol. The results are evaluated, namely the results will either be a failure or success with results for latency, loss, and number of hops. In an embodiment, if multiple protocols are successful, the module selects the one with the least latency and/or least loss and/or based on the number of hops found. The selected protocol is noted for this egress IP (internal network). The adaptive module caches this information for the configured internal. At the end of this interval, it can again detects the best protocol to be used on the internal network for the trace. 
     § 16.3 Adaptive Protocol Detection for the Destination 
     In a similar manner as protocol detection for the internal network, the module can find the best protocol to use for the trace to the destination  640  by sending probes by doing traces one by one using the configured protocols. The module checks which protocol can reach the destination IP. The module detects the best protocol by checking which protocol could reach the egress—with the least latency and/or least loss and/or based on the number of hops found. If the destination  640  could not be reached using either TCP, UDP, or ICMP protocol then it gives the default protocol, which comes in the policy, as the protocol to be used for the destination. 
     The Adaptive Trace, aka “CloudPath,” is called to detect the best protocol to reach the destination. The protocol result from the Adaptive Trace module is used for doing a trace to the destination. 
     § 16.3 Adaptive Protocol Detection for the Cloud Nodes 
     The module also detects if the request will go through the cloud-based system  100 , and passes the protocol type as adaptive, and the node  150  finds the best protocol to be used for reverse trace to the egress as well the best protocol to be used for forward trace to the destination. 
     § 16.4 Results 
     For the direct case where the trace is not through the cloud-based system  100 , the application  350  determines the destination  604  is not through the cloud-based system  100 . 
     The trace module combines the result for the direct case from 
     1) Trace to Egress using the protocol suggested by the adaptive module, and 
     2) Trace to the destination using the protocol suggested by the adaptive module. 
     It creates the Host to the Egress hops using trace results from the internal network and Egress to Destination hops using the results from tracing to the destination. The results are sent to the cloud-based system  100  and the user  102  or administrator can view these results on a dashboard. 
     The case wherein the trace is through the cloud-based system  100 , the application  604  finds the domain goes via the node  150 . It combines the results from— 
     1) Results up to the Egress using protocol suggested by the adaptive module, 
     2) Results from the node  150  to Egress using the protocol suggested by the adaptive module running on the node  150 , and 
     3) Results from the node  150  to the destination using the protocol suggested by the adaptive module running on the node  150 . 
     The combined results are sent to the cloud-based system  100  and the user  102  or administrator can view these results on a dashboard. 
     § 16.5 Adaptive Trace Process 
       FIG. 36  is a flowchart of a process  800  for an adaptive trace determination between two points in a network, such as a user device  300 , an egress from an internal network, a cloud node  150 , and a destination  640 . The process  800  is described with reference to a software module that is executed by one of the user device  300  with the application  350  and the enforcement nodes  150  associated with the cloud-based system  100 . The process  800  can be implemented as a method that includes steps, via a processing device configured to execute the steps, and via a non-transitory computer-readable medium that includes instructions that cause one or more processors to implement the steps. 
     The process  800  includes obtaining policy information related to a trace (step  801 ); performing a plurality of traces, from a start point to an end point in a network, using the different protocols based on the policy information (step  802 ); evaluating which of the plurality of traces reach the end point, and evaluating any of average latency of the plurality of traces, average loss of the plurality of traces, and a number of hops found, for each of the plurality of traces that reach the end point (step  803 ); and selecting a protocol of the different protocols to use for the trace based on the evaluating ( 804 ). 
     The different protocols can include Internet Control Message Protocol (ICMP), Transmission Control Protocol (TCP), and User Datagram Protocol (UDP). The selecting can be based on any of a least average latency of the plurality of traces and a least average loss of the plurality of traces. The policy information can include starting hop, ending hop, protocols to be used for egress and destination, number of packets to send, delay between the packets, User Datagram Protocol (UDP) and Transmission Control Protocol (TCP) ports for egress and destination, destination domain or address, intervals to be used, and a default protocol to used for egress and destination in case of failure. 
     The process  800  can be performed by a user device as the start point, and the end point includes an egress Internet Protocol (IP) address for an internal network. The process  800  can be performed responsive to any of the egress IP address change and a defined interval. For a given user device, a given egress IP, and a destination, the selected protocol can be different in the internal network from the selected protocol to the destination. The process  800  can further include making a call to a node in a cloud-based system to determine the egress IP. 
     The process  800  can be performed by a cloud node in a cloud-based system as the start point, and the end point includes a destination. 
     The process  800  can further include performing the trace with the selected protocol; and combining a plurality of results including the trace to obtain data from a user device to a destination through an internal network. 
     § 16.6 Examples of the Adaptive Trace Process 
     A key aspect of the adaptive trace process is to look at TCP or UDP or ICMP and then determine which of these protocols for tracing have the least packet loss and select the protocol for the adaptive trace. Of course, this can extend to any other trace path protocols, e.g., routing protocols, and is not limited to TCP/ICMP/UDP. 
     In an example embodiment, the adaptive trace can send some number of trace packets at the different protocols, e.g., TCP, UDP, and ICMP. Then we find from these which fit the configured criteria (say Least Loss). For example—If TCP, we could reach the destination, If with UDP we could not reach the destination, and If ICMP we could reach the destination. Then we compare TCP and UDP to see which one gave the least Loss (assuming the selection is to use Least Loss) and select the protocol. For Egress our default for TCP is TCP BGP Port (179). When we send results to back end we specify which protocol we used for each leg. We can make the decision based on Least Loss, Least Latency, or number of Hops. 
     § 17.0 Conclusion 
     It will be appreciated that some embodiments described herein may include one or more generic or specialized processors (“one or more processors”) such as microprocessors; Central Processing Units (CPUs); Digital Signal Processors (DSPs): customized processors such as Network Processors (NPs) or Network Processing Units (NPUs), Graphics Processing Units (GPUs), or the like; Field Programmable Gate Arrays (FPGAs); and the like along with unique stored program instructions (including both software and firmware) for control thereof to implement, in conjunction with certain non-processor circuits, some, most, or all of the functions of the methods and/or systems described herein. Alternatively, some or all functions may be implemented by a state machine that has no stored program instructions, or in one or more Application-Specific Integrated Circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic or circuitry. Of course, a combination of the aforementioned approaches may be used. For some of the embodiments described herein, a corresponding device in hardware and optionally with software, firmware, and a combination thereof can be referred to as “circuitry configured or adapted to,” “logic configured or adapted to,” etc. perform a set of operations, steps, methods, processes, algorithms, functions, techniques, etc. on digital and/or analog signals as described herein for the various embodiments. 
     Moreover, some embodiments may include a non-transitory computer-readable storage medium having computer-readable code stored thereon for programming a computer, server, appliance, device, processor, circuit, etc. each of which may include a processor to perform functions as described and claimed herein. Examples of such computer-readable storage mediums include, but are not limited to, a hard disk, an optical storage device, a magnetic storage device, a Read-Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), Flash memory, and the like. When stored in the non-transitory computer-readable medium, software can include instructions executable by a processor or device (e.g., any type of programmable circuitry or logic) that, in response to such execution, cause a processor or the device to perform a set of operations, steps, methods, processes, algorithms, functions, techniques, etc. as described herein for the various embodiments. 
     The foregoing sections include headers for various embodiments and those skilled in the art will appreciate these various embodiments may be used in combination with one another as well as individually. Although the present disclosure has been illustrated and described herein with reference to preferred embodiments and specific examples thereof, it will be readily apparent to those of ordinary skill in the art that other embodiments and examples may perform similar functions and/or achieve like results. All such equivalent embodiments and examples are within the spirit and scope of the present disclosure, are contemplated thereby, and are intended to be covered by the following claims.