Unless otherwise indicated herein, the materials described in this section are not prior art to the claims in this application and are not admitted to be prior art by inclusion in this section.
The Internet is a global system of interconnected computer networks that use the standardized Internet Protocol Suite (TCP/IP), including Transmission Control Protocol (TCP) and the Internet Protocol (IP), to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic and optical networking technologies. The Internet carries a vast range of information resources and services, such as the interlinked hypertext documents on the World Wide Web (WWW) and the infrastructure to support electronic mail. The Internet backbone refers to the principal data routes between large, strategically interconnected networks and core routers in the Internet. These data routes are hosted by commercial, government, academic, and other high-capacity network centers, the Internet exchange points and network access points that interchange Internet traffic between the countries, continents and across the oceans of the world. Traffic interchange between Internet service providers (often Tier 1 networks) participating in the Internet backbone exchange traffic by privately negotiated interconnection agreements, primarily governed by the principle of settlement-free peering.
The Transmission Control Protocol (TCP) is one of the core protocols of the Internet protocol suite (IP) described in RFC 675 and RFC 793, and the entire suite is often referred to as TCP/IP. TCP provides reliable, ordered and error-checked delivery of a stream of octets between programs running on computers connected to a local area network, intranet or the public Internet. It resides at the transport layer. Web browsers typically use TCP when they connect to servers on the World Wide Web, and used to deliver email and transfer files from one location to another. HTTP, HTTPS, SMTP, POP3, IMAP, SSH, FTP, Telnet and a variety of other protocols that are typically encapsulated in TCP. As the transport layer of TCP/IP suite, the TCP provides a communication service at an intermediate level between an application program and the Internet Protocol (IP). Due to network congestion, traffic load balancing, or other unpredictable network behavior, IP packets can be lost, duplicated, or delivered out of order. TCP detects these problems, requests retransmission of lost data, rearranges out-of-order data, and even helps minimize network congestion to reduce the occurrence of the other problems. Once the TCP receiver has reassembled the sequence of octets originally transmitted, it passes them to the receiving application. Thus, TCP abstracts the application's communication from the underlying networking details. The TCP is utilized extensively by many of the Internet's most popular applications, including the World Wide Web (WWW), E-mail, File Transfer Protocol, Secure Shell, peer-to-peer file sharing, and some streaming media applications.
While IP layer handles actual delivery of the data, TCP keeps track of the individual units of data transmission, called segments, which a message is divided into for efficient routing through the network. For example, when an HTML file is sent from a web server, the TCP software layer of that server divides the sequence of octets of the file into segments and forwards them individually to the IP software layer (Internet Layer). The Internet Layer encapsulates each TCP segment into an IP packet by adding a header that includes (among other data) the destination IP address. When the client program on the destination computer receives them, the TCP layer (Transport Layer) reassembles the individual segments and ensures they are correctly ordered and error free as it streams them to an application.
The TCP protocol operations may be divided into three phases. Connections must be properly established in a multi-step handshake process (connection establishment) before entering the data transfer phase. After data transmission is completed, the connection termination closes established virtual circuits and releases all allocated resources. A TCP connection is typically managed by an operating system through a programming interface that represents the local end-point for communications, the Internet socket. During the duration of a TCP connection, the local end-point undergoes a series of state changes.
Since TCP/IP is based on the client/server model of operation, the TCP connection setup involves the client and server preparing for the connection by performing an OPEN operation. A client process initiates a TCP connection by performing an active OPEN, sending a SYN message to a server. A server process using TCP prepares for an incoming connection request by performing a passive OPEN. Both devices create for each TCP session a data structure used to hold important data related to the connection, called a Transmission Control Block (TCB).
There are two different kinds of OPEN, named ‘Active OPEN’ and ‘Passive OPEN’. In Active OPEN the client process using TCP takes the “active role” and initiates the connection by actually sending a TCP message to start the connection (a SYN message). In Passive OPEN the server process designed to use TCP is contacting TCP and saying: “I am here, and I am waiting for clients that may wish to talk to me to send me a message on the following port number”. The OPEN is called passive because aside from indicating that the process is listening, the server process does nothing. A passive OPEN can in fact specify that the server is waiting for an active OPEN from a specific client, though not all TCP/IP APIs support this capability. More commonly, a server process is willing to accept connections from all corners. Such a passive OPEN is said to be unspecified.
In passive OPEN, the TCP uses a three-way handshake, and before a client attempts to connect with a server, the server must first bind to and listen at a port to open it up for connections. Once the Passive OPEN is established, a client may initiate an Active OPEN. To establish a connection, the three-way (or 3-step) handshake occurs:                1. SYN: The active open is performed by the client sending a SYN to the server. The client sets the segment's sequence number to a random value A.        2. SYN-ACK: In response, the server replies with a SYN-ACK. The acknowledgment number is set to one more than the received sequence number, i.e. A+1, and the sequence number that the server chooses for the packet is another random number, B.        3. ACK: Finally, the client sends an ACK back to the server. The sequence number is set to the received acknowledgement value, i.e. A+1, and the acknowledgement number is set to one more than the received sequence number i.e. B+1.        
At this point, both the client and server have received an acknowledgment of the connection. The steps 1, 2 establish the connection parameter (sequence number) for one direction and it is acknowledged. The steps 2, 3 establish the connection parameter (sequence number) for the other direction and it is acknowledged, and then a full-duplex communication is established.
The Internet Protocol (IP) is the principal communications protocol used for relaying datagrams (packets) across a network using the Internet Protocol Suite. Responsible for routing packets across network boundaries, it is the primary protocol that establishes the Internet. IP is the primary protocol in the Internet Layer of the Internet Protocol Suite and has the task of delivering datagrams from the source host to the destination host based on their addresses. For this purpose, IP defines addressing methods and structures for datagram encapsulation. Internet Protocol Version 4 (IPv4) is the dominant protocol of the Internet. IPv4 is described in Internet Engineering Task Force (IETF) Request for Comments (RFC) 791 and RFC 1349, and the successor, Internet Protocol Version 6 (IPv6), is currently active and in growing deployment worldwide. IPv4 uses 32-bit addresses (providing 4 billion: 4.3×109 addresses), while IPv6 uses 128-bit addresses (providing 340 undecillion or 3.4×1038 addresses), as described in RFC 2460.
An overview of an IP-based packet 15 is shown in FIG. 2a. The packet may be generally segmented into the IP data 16b to be carried as payload, and the IP header 16f. The IP header 16f contains the IP address of the source as Source IP Address field 16d and the Destination IP Address field 16c. In most cases, the IP header 16f and the payload 16b are further encapsulated by adding a Frame Header 16e and Frame Footer 16a used by higher layer protocols.
The Internet Protocol is responsible for addressing hosts and routing datagrams (packets) from a source host to the destination host across one or more IP networks. For this purpose the Internet Protocol defines an addressing system that has two functions. Addresses identify hosts and provide a logical location service. Each packet is tagged with a header that contains the meta-data for the purpose of delivery. This process of tagging is also called encapsulation. IP is a connectionless protocol for use in a packet-switched Link Layer network, and does not need circuit setup prior to transmission. The aspects of guaranteeing delivery, proper sequencing, avoidance of duplicate delivery, and data integrity are addressed by an upper transport layer protocol (e.g., TCP—Transmission Control Protocol and UDP—User Datagram Protocol).
The main aspects of the IP technology are IP addressing and routing. Addressing refers to how IP addresses are assigned to end hosts and how sub-networks of IP host addresses are divided and grouped together. IP routing is performed by all hosts, but most importantly by internetwork routers, which typically use either Interior Gateway Protocols (IGPs) or External Gateway Protocols (EGPs) to help make IP datagram forwarding decisions across IP connected networks. Core routers serving in the Internet backbone commonly use the Border Gateway Protocol (BGP) as per RFC 4098 or Multi-Protocol Label Switching (MPLS). Other prior art publications relating to Internet related protocols and routing include the following chapters of the publication number 1-587005-001-3 by Cisco Systems, Inc. (July 1999) entitled: “Internetworking Technologies Handbook”, which are all incorporated in their entirety for all purposes as if fully set forth herein: Chapter 5: “Routing Basics” (pages 5-1 to 5-10), Chapter 30: “Internet Protocols” (pages 30-1 to 30-16), Chapter 32: “IPv6” (pages 32-1 to 32-6), Chapter 45: “OSI Routing” (pages 45-1 to 45-8) and Chapter 51: “Security” (pages 51-1 to 51-12), as well as in a IBM Corporation, International Technical Support Organization Redbook Documents No. GG24-4756-00, entitled: “Local area Network Concepts and Products: LAN Operation Systems and management”, 1st Edition May 1996, Redbook Document No. GG24-4338-00, entitled: “Introduction to Networking Technologies”, 1st Edition April 1994, Redbook Document No. GG24-2580-01 “IP Network Design Guide”, 2nd Edition June 1999, and Redbook Document No. GG24-3376-07 “TCP/IP Tutorial and Technical Overview”, ISBN 0738494682 8th Edition December 2006, which are incorporated in their entirety for all purposes as if fully set forth herein.
An Internet packet typically includes a value of Time-to-live (TTL) for avoiding the case of packet looping endlessly. The initial TTL value is set in the header of the packet, and each router in the packet path subtracts one from the TTL field, and the packet is discarded upon the value exhaustion. Since the packets may be routed via different and disparately located routers and servers, the TTL of the packets reaching the ultimate destination computer are expected to vary.
The Internet architecture employs a client-server model, among other arrangements. The terms ‘server’ or ‘server computer’ relates herein to a device or computer (or a plurality of computers) connected to the Internet and is used for providing facilities or services to other computers or other devices (referred to in this context as ‘clients’) connected to the Internet. A server is commonly a host that has an IP address and executes a ‘server program’, and typically operates as a socket listener. Many servers have dedicated functionality such as web server, Domain Name System (DNS) server (described in RFC 1034 and RFC 1035), Dynamic Host Configuration Protocol (DHCP) server (described in RFC 2131 and RFC 3315), mail server, File Transfer Protocol (FTP) server and database server. Similarly, the term ‘client’ is used herein to include, but not limited to, a program or to a device or a computer (or a series of computers) executing this program, which accesses a server over the Internet for a service or a resource. Clients commonly initiate connections that a server may accept. For non-limiting example, web browsers are clients that connect to web servers for retrieving web pages, and email clients connect to mail storage servers for retrieving mails.
The Hypertext Transfer Protocol (HTTP) is an application protocol for distributed, collaborative, hypermedia information systems, commonly used for communication over the Internet. Hypertext is. HTTP is the protocol to exchange or transfer hypertext, which is a structured text that uses logical links (hyperlinks) between nodes containing text. HTTP version 1.1 was standardized as RFC 2616 (June 1999), which was replaced by a set of standards (obsoleting RFC 2616), including RFC 7230-HTTP/1.1: Message Syntax and Routing, RFC 7231-HTTP/1.1: Semantics and Content, RFC 7232-HTTP/1.1: Conditional Requests, RFC 7233-HTTP/1.1: Range Requests, RFC 7234-HTTP/1.1: Caching, and RFC 7235-HTTP/1.1: Authentication. HTTP functions as a request-response protocol in the client-server computing model. A web browser, for example, may be the client and an application running on a computer hosting a website may be the server. The client submits an HTTP request message to the server. The server, which provides resources such as HTML files and other content, or performs other functions on behalf of the client, returns a response message to the client. The response contains completion status information about the request and may also contain requested content in its message body. A web browser is an example of a user agent (UA). Other types of user agent include the indexing software used by search providers (web crawlers), voice browsers, mobile apps and other software that accesses, consumes or displays web content.
HTTP is designed to permit intermediate network elements to improve or enable communications between clients and servers. High-traffic websites often benefit from web cache servers that deliver content on behalf of upstream servers to improve response time. Web browsers cache previously accessed web resources and reuse them when possible, to reduce network traffic. HTTP proxy servers at private network boundaries can facilitate communication for clients without a globally routable address, by relaying messages with external servers. HTTP is an application layer protocol designed within the framework of the Internet Protocol Suite. Its definition presumes an underlying and reliable transport layer protocol, and Transmission Control Protocol (TCP) is commonly used. However, HTTP can use unreliable protocols such as the User Datagram Protocol (UDP), for example, in the Simple Service Discovery Protocol (SSDP). HTTP resources are identified and located on the network by Uniform Resource Identifiers (URIs) or, more specifically, Uniform Resource Locators (URLs), using the http or https URI schemes. URIs and hyperlinks in Hypertext Markup Language (HTML) documents form webs of inter-linked hypertext documents. An HTTP session is a sequence of network request-response transactions. An HTTP client initiates a request by establishing a Transmission Control Protocol (TCP) connection to a particular port on a server. An HTTP server listening on that port waits for a client's request message. Upon receiving the request, the server sends back a status line, such as “HTTP/1.1 200 OK”, and a message of its own. The body of this message is typically the requested resource, although an error message or other information may also be returned. HTTP is a stateless protocol. A stateless protocol does not require the HTTP server to retain information or status
HTTP persistent connection, also called HTTP keep-alive, or HTTP connection reuse, refers to using a single TCP connection to send and receive multiple HTTP requests/responses, as opposed to opening a new connection for every single request/response pair. Persistent connections provide a mechanism by which a client and a server can signal the close of a TCP connection. This signaling takes place using the Connection header field. The HTTP persistent connection is described in IETF RFC 2616, entitled: “Hypertext Transfer Protocol—HTTP/1.1”. In HTTP 1.1, all connections are considered persistent unless declared otherwise. The HTTP persistent connections do not use separate keepalive messages, but they allow multiple requests to use a single connection. The advantages of using persistent connections involve lower CPU and memory usage (because fewer connections are open simultaneously), enabling HTTP pipelining of requests and responses, reduced network congestion (due to fewer TCP connections), and reduced latency in subsequent requests (due to minimal handshaking). Any connection herein may use, or be based on, an HTTP persistent connection.
An Operating System (OS) is software that manages computer hardware resources and provides common services for computer programs. The operating system is an essential component of any system software in a computer system, and most application programs usually require an operating system to function. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently make a system call to an OS function or be interrupted by it. Common features typically supported by operating systems include process management, interrupts handling, memory management, file system, device drivers, networking (such as TCP/IP and UDP), and Input/Output (I/O) handling. Examples of popular modern operating systems include Android, BSD, iOS, Linux, OS X, QNX, Microsoft Windows, Windows Phone, and IBM z/OS.
A server device (in server/client architecture) typically offers information resources, services, and applications to clients, and is using a server dedicated or oriented operating system. Current popular server operating systems are based on Microsoft Windows (by Microsoft Corporation, headquartered in Redmond, Wash., U.S.A.), Unix, and Linux-based solutions, such as the ‘Windows Server 2012’ server operating system is part of the Microsoft ‘Windows Server’ OS family, that was released by Microsoft on 2012, providing enterprise-class datacenter and hybrid cloud solutions that are simple to deploy, cost-effective, application-focused, and user-centric, and is described in Microsoft publication entitled: “Inside-Out Windows Server 2012”, by William R. Stanek, published 2013 by Microsoft Press, which is incorporated in its entirety for all purposes as if fully set forth herein.
Unix operating systems are widely used in servers. Unix is a multitasking, multiuser computer operating system that exists in many variants, and is characterized by a modular design that is sometimes called the “Unix philosophy,” meaning the OS provides a set of simple tools that each perform a limited, well-defined function, with a unified filesystem as the main means of communication, and a shell scripting and command language to combine the tools to perform complex workflows. Unix was designed to be portable, multi-tasking and multi-user in a time-sharing configuration, and Unix systems are characterized by various concepts: the use of plain text for storing data; a hierarchical file system; treating devices and certain types of Inter-Process Communication (IPC) as files; and the use of a large number of software tools, small programs that can be strung together through a command line interpreter using pipes, as opposed to using a single monolithic program that includes all of the same functionality. Under Unix, the operating system consists of many utilities along with the master control program, the kernel. The kernel provides services to start and stop programs, handles the file system and other common “low level” tasks that most programs share, and schedules access to avoid conflicts when programs try to access the same resource or device simultaneously. To mediate such access, the kernel has special rights, reflected in the division between user-space and kernel-space. Unix is described in a publication entitled: “UNIX Tutorial” by tutorialspoint.com, downloaded on July 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
A client device (in server/client architecture) typically receives information resources, services, and applications from servers, and is using a client dedicated or oriented operating system. Current popular server operating systems are based on Microsoft Windows (by Microsoft Corporation, headquartered in Redmond, Wash., U.S.A.), which is a series of graphical interface operating systems developed, marketed, and sold by Microsoft. Microsoft Windows is described in Microsoft publications entitled: “Windows Internals—Part 1” and “Windows Internals—Part 2”, by Mark Russinovich, David A. Solomon, and Alex Ioescu, published by Microsoft Press in 2012, which are both incorporated in their entirety for all purposes as if fully set forth herein. Windows 8 is a personal computer operating system developed by Microsoft as part of Windows NT family of operating systems, that was released for general availability on October 2012, and is described in Microsoft Press 2012 publication entitled: “Introducing Windows 8—An Overview for IT Professionals” by Jerry Honeycutt, which is incorporated in its entirety for all purposes as if fully set forth herein.
Chrome OS is a Linux kernel-based operating system designed by Google Inc. out of Mountain View, Calif., U.S.A., to work primarily with web applications. The user interface takes a minimalist approach and consists almost entirely of just the Google Chrome web browser; since the operating system is aimed at users who spend most of their computer time on the Web, the only “native” applications on Chrome OS are a browser, media player and file manager, and hence the Chrome OS is almost a pure web thin client OS.
The Chrome OS is described as including a three-tier architecture: firmware, browser and window manager, and system-level software and userland services. The firmware contributes to fast boot time by not probing for hardware, such as floppy disk drives, that are no longer common on computers, especially netbooks. The firmware also contributes to security by verifying each step in the boot process and incorporating system recovery. The system-level software includes the Linux kernel that has been patched to improve boot performance. The userland software has been trimmed to essentials, with management by Upstart, which can launch services in parallel, re-spawn crashed jobs, and defer services in the interest of faster booting. The Chrome OS user guide is described in the Samsung Electronics Co., Ltd. presentation entitled: “Google™ Chrome OS USER GUIDE” published 2011, which is incorporated in its entirety for all purposes as if fully set forth herein.
A mobile operating system (also referred to as mobile OS), is an operating system that operates a smartphone, tablet, PDA, or other mobile device. Modern mobile operating systems combine the features of a personal computer operating system with other features, including a touchscreen, cellular, Bluetooth, Wi-Fi, GPS mobile navigation, camera, video camera, speech recognition, voice recorder, music player, near field communication and infrared blaster. Currently popular mobile OS are Android, Symbian, Apple iOS, BlackBerry, MeeGo, Windows Phone, and Bada. Mobile devices with mobile communications capabilities (e.g. smartphones) typically contain two mobile operating systems—the main user-facing software platform is supplemented by a second low-level proprietary real-time operating system which operates the radio and other hardware.
Android is an open source and Linux-based mobile operating system (OS) based on the Linux kernel that is currently offered by Google. With a user interface based on direct manipulation, Android is designed primarily for touchscreen mobile devices such as smartphones and tablet computers, with specialized user interfaces for televisions (Android TV), cars (Android Auto), and wrist watches (Android Wear). The OS uses touch inputs that loosely correspond to real-world actions, such as swiping, tapping, pinching, and reverse pinching to manipulate on-screen objects, and a virtual keyboard. Despite being primarily designed for touchscreen input, it also has been used in game consoles, digital cameras, and other electronics. The response to user input is designed to be immediate and provides a fluid touch interface, often using the vibration capabilities of the device to provide haptic feedback to the user. Internal hardware such as accelerometers, gyroscopes and proximity sensors are used by some applications to respond to additional user actions, for example adjusting the screen from portrait to landscape depending on how the device is oriented, or allowing the user to steer a vehicle in a racing game by rotating the device, simulating control of a steering wheel.
Android devices boot to the homescreen, the primary navigation and information point on the device, which is similar to the desktop found on PCs. Android homescreens are typically made up of app icons and widgets; app icons launch the associated app, whereas widgets display live, auto-updating content such as the weather forecast, the user's email inbox, or a news ticker directly on the homescreen. A homescreen may be made up of several pages that the user can swipe back and forth between, though Android's homescreen interface is heavily customizable, allowing the user to adjust the look and feel of the device to their tastes. Third-party apps available on Google Play and other app stores can extensively re-theme the homescreen, and even mimic the look of other operating systems, such as Windows Phone. The Android OS is described in a publication entitled: “Android Tutorial”, downloaded from tutorialspoint.com on July 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
iOS (previously iPhone OS) from Apple Inc. (headquartered in Cupertino, Calif., U.S.A.) is a mobile operating system distributed exclusively for Apple hardware. The user interface of the iOS is based on the concept of direct manipulation, using multi-touch gestures. Interface control elements consist of sliders, switches, and buttons. Interaction with the OS includes gestures such as swipe, tap, pinch, and reverse pinch, all of which have specific definitions within the context of the iOS operating system and its multi-touch interface. Internal accelerometers are used by some applications to respond to shaking the device (one common result is the undo command) or rotating it in three dimensions (one common result is switching from portrait to landscape mode). The iOS is described in the publication entitled: “IOS Tutorial”, downloaded from tutorialspoint.com on July 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
Operating Systems:
An Operating System (OS) is software that manages computer hardware resources and provides common services for computer programs. The operating system is an essential component of any system software in a computer system, and most application programs usually require an operating system to function. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and will frequently make a system call to an OS function or be interrupted by it. Common features typically supported by operating systems include process management, interrupts handling, memory management, file system, device drivers, networking (such as TCP/IP and UDP), and Input/Output (I/O) handling. Examples of popular modern operating systems include Android, BSD, iOS, Linux, OS X, QNX, Microsoft Windows, Windows Phone, and IBM z/OS.
Process Management:
The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with the hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and execution of application programs. Executing an application program involves the creation of a process by the operating system kernel which assigns memory space and other resources, establishes a priority for the process in multi-tasking systems, loads program binary code into memory, and initiates execution of the application program which then interacts with the user and with hardware devices. The OS must allocate resources to processes, enable processes to share and exchange information, protect the resources of each process from other processes, and enable synchronization among processes. The OS maintains a data structure for each process, which describes the state and resource ownership of that process, and which enables the OS to exert control over each process.
In many modern operating systems, there can be more than one instance of a program loaded in memory at the same time; for example, more than one user could be executing the same program, each user having separate copies of the program loaded into memory. With some programs, known as re-entrant type, it is possible to have one copy loaded into memory, while several users have shared access to it so that they each can execute the same program-code. The processor at any instant can only be executing one instruction from one program but several processes can be sustained over a period of time by assigning each process to the processor at intervals while the remainder become temporarily inactive. A number of processes being executed over a period of time instead of at the same time is called concurrent execution. A multiprogramming or multitasking OS is a system executing many processes concurrently. A multiprogramming requires that the processor be allocated to each process for a period of time, and de-allocated at an appropriate moment. If the processor is de-allocated during the execution of a process, it must be done in such a way that it can be restarted later as easily as possible.
There are two typical ways for an OS to regain control of the processor during a program's execution in order for the OS to perform de-allocation or allocation: The process issues a system call (sometimes called a software interrupt); for example, an I/O request occurs requesting to access a file on hard disk. Alternatively, a hardware interrupt occurs; for example, a key was pressed on the keyboard, or a timer runs out (used in pre-emptive multitasking). The stopping of one process and starting (or restarting) of another process is called a context switch or context change. In many modern operating systems, processes can consist of many sub-processes. This introduces the concept of a thread. A thread may be viewed as a sub-process; that is, a separate, independent sequence of execution within the code of one process. Threads are becoming increasingly important in the design of distributed and client-server systems and in software run on multi-processor systems.
Modes:
Many contemporary processors incorporate a mode bit to define the execution capability of a program in the processor. This bit can be set to a kernel mode or a user mode. A kernel mode is also commonly referred to as supervisor mode, monitor mode or ring 0. In kernel mode, the processor can execute every instruction in its hardware repertoire, whereas in user mode, it can only execute a subset of the instructions. Instructions that can be executed only in kernel mode are called kernel, privileged or protected instructions to distinguish them from the user mode instructions. For example, I/O instructions are privileged. So, if an application program executes in user mode, it cannot perform its own I/O, and must request the OS to perform I/O on its behalf. The system may logically extend the mode bit to define areas of memory to be used when the processor is in kernel mode versus user mode. If the mode bit is set to kernel mode, the process executing in the processor can access either the kernel or user partition of the memory. However, if user mode is set, the process can reference only the user memory space, hence two classes of memory are defined, the user space and the system space (or kernel, supervisor or protected space). In general, the mode bit extends the operating system's protection rights, and is set by the user mode trap instruction, also called a supervisor call instruction. This instruction sets the mode bit, and branches to a fixed location in the system space. Since only the system code is loaded in the system space, only the system code can be invoked via a trap. When the OS has completed the supervisor call, it resets the mode bit to user mode prior to the return.
Computer operating systems provide different levels of access to resources, and these hierarchical protection domains are often referred to as ‘protection rings’, and are used to protect data and functionality from faults (by improving fault tolerance) and malicious behaviour (by providing computer security). A protection ring is one of two or more hierarchical levels or layers of privilege within the architecture of a computer system. These levels may be hardware-enforced by some CPU architectures that provide different CPU modes at the hardware or microcode level. Rings are arranged in a hierarchy from most privileged (most trusted, usually numbered zero) to least privileged (least trusted, usually with the highest ring number). On most operating systems, kernel mode or ‘Ring 0’ is the level with the most privileges and interacts most directly with the physical hardware such as the CPU and memory. Special gates between rings are provided to allow an outer ring to access an inner ring's resources in a predefined manner, as opposed to allowing arbitrary usage. Correctly gating access between rings can improve security by preventing programs from one ring or privilege level from misusing resources intended for programs in another. For example, spyware running as a user program in Ring 3 should be prevented from turning on a web camera without informing the user, since hardware access should be a Ring 1 function reserved for device drivers. Programs such as web browsers running in higher numbered rings must request access to the network, a resource restricted to a lower numbered ring.
Kernel:
With the aid of the firmware and device drivers, the kernel provides the most basic level of control over all of the computer's hardware devices. It manages memory access for programs in the RAM, it determines which programs get access to which hardware resources, it sets up or resets the CPU's operating states for optimal operation at all times, and it organizes the data for long-term non-volatile storage with file systems on such media as disks, tapes, flash memory, etc. The part of the system executing in kernel supervisor state is called the kernel, or nucleus, of the operating system. The kernel operates as trusted software, meaning that when it was designed and implemented, it was intended to implement protection mechanisms that could not be covertly changed through the actions of untrusted software executing in user space. Extensions to the OS execute in user mode, so the OS does not rely on the correctness of those parts of the system software for correct operation of the OS. Hence, a fundamental design decision for any function to be incorporated into the OS is whether it needs to be implemented in the kernel. If it is implemented in the kernel, it will execute in kernel (supervisor) space, and have access to other parts of the kernel. It will also be trusted software by the other parts of the kernel. If the function is implemented to execute in user mode, it will have no access to kernel data structures.
There are two techniques by which a program executing in user mode can request the kernel's services, namely ‘System call’ and ‘Message passing’. Operating systems are typically with one or the other of these two facilities, but commonly not both. Assuming that a user process wishes to invoke a particular target system function, in the system call approach, the user process uses the trap instruction, so the system call should appear to be an ordinary procedure call to the application program; the OS provides a library of user functions with names corresponding to each actual system call. Each of these stub functions contains a trap to the OS function, and when the application program calls the stub, it executes the trap instruction, which switches the CPU to kernel mode, and then branches (indirectly through an OS table), to the entry point of the function which is to be invoked. When the function completes, it switches the processor to user mode and then returns control to the user process; thus simulating a normal procedure return. In the message passing approach, the user process constructs a message, that describes the desired service, and then it uses a trusted send function to pass the message to a trusted OS process. The send function serves the same purpose as the trap; that is, it carefully checks the message, switches the processor to kernel mode, and then delivers the message to a process that implements the target functions. Meanwhile, the user process waits for the result of the service request with a message receive operation. When the OS process completes the operation, it sends a message back to the user process.
Interrupts Handling:
Interrupts are central to operating systems, as they provide an efficient way for the operating system to interact with and react to its environment. Interrupts are typically handled by the operating system's kernel, and provide a computer with a way of automatically saving local register contexts, and running specific code in response to events. When an interrupt is received, the computer's hardware automatically suspends whatever program is currently running, saves its status, and runs computer code previously associated with the interrupt. When a hardware device triggers an interrupt, the operating system's kernel decides how to deal with this event, generally by running some processing code. The amount of code being run depends on the priority of the interrupt, and the processing of hardware interrupts is executed by a device driver, which may be either part of the operating system's kernel, part of another program, or both. Device drivers may then relay information to a running program by various means. A program may also trigger an interrupt to the operating system. For example, if a program wishes to access an hardware (such as a peripheral), it may interrupt the operating system's kernel, which causes control to be passed back to the kernel. The kernel will then process the request. If a program wishes additional resources (or wishes to shed resources) such as memory, it will trigger an interrupt to get the kernel's attention. Each interrupt has its own interrupt handler. The number of hardware interrupts is limited by the number of interrupt request (IRQ) lines to the processor, but there may be hundreds of different software interrupts. Interrupts are a commonly used technique for computer multitasking, especially in real-time computing systems, which are commonly referred to as interrupt-driven systems.
Memory Management:
A multiprogramming operating system kernel is responsible for managing all system memory which is currently in use by programs, ensuring that a program does not interfere with memory already in use by another program. Since programs time share, each program must have independent access to memory. Memory protection enables the kernel to limit a process' access to the computer's memory. Various methods of memory protection exist, including memory segmentation and paging. In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should allow a running program to access. Attempts to access other addresses will trigger an interrupt which will cause the CPU to re-enter supervisor mode, placing the kernel in charge. This is called a segmentation violation (or Seg-V), and the kernel will generally resort to terminating the offending program, and will report the error.
Memory management further provides ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when no longer needed. This is critical for any advanced computer system where more than a single process might be underway at any time. Several methods have been devised that increase the effectiveness of memory management. Virtual memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the effectively available amount of RAM using paging or swapping to secondary storage. The quality of the virtual memory manager can have an extensive effect on overall system performance.
File System:
Commonly a file system (or filesystem) is used to control how data is stored and retrieved. By separating the data into individual pieces, and giving each piece a name, the information is easily separated and identified, where each piece of data is called a “file”. The structure and logic rules used to manage the groups of information and their names is called a “file system”. There are many different kinds of file systems. Each one has a different structure and logic, properties of speed, flexibility, security, size and more. Some file systems have been designed to be used for specific applications. For example, the ISO 9660 file system is designed specifically for optical discs. File systems can be used on many different kinds of storage devices. Some file systems are used on local data storage devices; others provide file access via a network protocol (for example, NFS, SMB, or 9P clients). Some file systems are “virtual”, in that the “files” supplied are computed on request (e.g. procfs) or are merely a mapping into a different file system used as a backing store. The file system manages access to both the content of files and the metadata about those files. It is responsible for arranging storage space; reliability, efficiency, and tuning with regard to the physical storage medium are important design considerations.
A disk file system takes advantages of the ability of disk storage media to randomly address data in a short amount of time. Additional considerations include the speed of accessing data following that initially requested and the anticipation that the following data may also be requested. This permits multiple users (or processes) access to various data on the disk without regard to the sequential location of the data. Examples include FAT (FAT12, FAT16, FAT32), exFAT, NTFS, HFS and HFS+, HPFS, UFS, ext2, ext3, ext4, XFS, btrfs, ISO 9660, Files-11, Veritas File System, VMFS, ZFS, ReiserFS and UDF. Some disk file systems are journaling file systems or versioning file systems.
TMPFS.
TMPFS (or tmpfs) is a common name for a temporary file storage facility on many Unix-like operating systems. While intended to appear as a mounted file system, it is stored in volatile memory instead of a non-volatile storage device. A similar construction is a RAM disk, which appears as a virtual disk drive and hosts a disk file system. The tmpfs is typically a file system based on SunOS virtual memory resources, which does not use traditional non-volatile media to store file data; instead, tmpfs files exist solely in virtual memory maintained by the UNIX kernel. Because tmpfs file systems do not use dedicated physical memory for file data, but instead use VM system resources and facilities, they can take advantage of kernel resource management policies. Tmpfs is designed primarily as a performance enhancement to allow short-lived files to be written and accessed without generating disk or network I/O. Tmpfs maximizes file manipulation speed while preserving UNIX file semantics. It does not require dedicated disk space for files and has no negative performance impact. The tmpfs is described in a Sun Microsystem Inc. paper entitled: “tmpfs: A Virtual Memory File System” by Peter Snyder, downloaded on July 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
Device Drivers:
A device driver is a specific type of computer software developed to allow interaction with hardware devices. Typically, this constitutes an interface for communicating with the device, through the specific computer bus or communications subsystem that the hardware is connected to, providing commands to and/or receiving data from the device, and on the other end, the requisite interfaces to the operating system and software applications. It is a specialized hardware-dependent computer program which is also operating system specific that enables another program, typically an operating system or applications software package or computer program running under the operating system kernel, to interact transparently with a hardware device, and usually provides the requisite interrupt handling necessary for any necessary asynchronous time-dependent hardware interfacing needs.
Networking:
Most operating systems support a variety of networking protocols, hardware, and applications for using them, allowing computers running dissimilar operating systems to participate in a common network, for sharing resources such as computing, files, printers, and scanners, using either wired or wireless connections. Networking can essentially allow a computer's operating system to access the resources of a remote computer, to support the same functions as it could if those resources were connected directly to the local computer. This includes everything from simple communication, to using networked file systems, or sharing another computer's graphics or sound hardware. Some network services allow the resources of a computer to be accessed transparently, such as SSH, which allows networked users direct access to a computer's command line interface. A client/server networking allows a program on a computer, called a client, to connect via a network to another computer, called a server. Servers offer (or host) various services to other network computers and users. These services are usually provided through ports or numbered access points beyond the server's network address. Each port number is usually associated with a maximum of one running program, which is responsible for handling requests to that port. A daemon, being a user program, can in turn access the local hardware resources of that computer by passing requests to the operating system kernel.
Input/Output (I/O) Handling:
An input/output (or I/O) is the communication between an information processing system (such as a computer) and the outside world, possibly a human or other information processing system. The inputs are typically the signals or data received by the system, and the outputs are the signals or data sent from it. I/O devices may be used by a person (or other system) to communicate with a computer. For instance, a keyboard or a mouse may be an input device for a computer, while monitors and printers are considered output devices for a computer. Devices for communication between computers, such as modems and network cards, typically serve for both input and output.
User Interface:
Every computer that is to be operated by a human being requires a user interface, usually referred to as a ‘shell’, and is essential if human interaction is to be supported. The user interface views the directory structure and requests services from the operating system that will acquire data from input hardware devices, such as a keyboard, mouse or credit card reader, and requests operating system services to display prompts, status messages and such on output hardware devices, such as a video monitor or printer. The two most common forms of a user interface have historically been the command-line interface, where computer commands are typed out line-by-line, and the Graphical User Interface (GUI), where a visual environment (most commonly a WIMP) is present. Typically the GUI is integrated into the kernel, allowing the GUI to be more responsive by reducing the number of context switches required for the GUI to perform its output functions.
WDM.
The Windows Driver Model (WDM), also known as the Win32 Driver Model, is a standard model defining a framework for device drivers specified by Microsoft, providing unified driver models. The WDM model is based on WDM drivers that are layered in a complex hierarchy and communicate with each other via I/O Request Packets (IRPs). The WDM was introduced with Windows 98 and Windows 2000 to replace VxD which was used on older versions of Windows such as Windows 95 and Windows 3.1, as well as the Windows NT Driver Model, and WDM drivers are usable on all of Microsoft's operating systems of Windows 95 and later. The WDM is described in the publication entitled: “Microsoft Windows Driver Model (WDM)”, by Mohamad (Hani) Atassy, submitted to Dr. Dennis R. Hafermann dated Jan. 28, 2002, and in publication entitled: “A Comparison of the Linux and Windows Device Driver Architecture”, by Melekam Tsegaye and Ricahrd Foss, both from Rhodes University, South-Africa, downloaded from the Internet on July 2014, both are incorporated in their entirety for all purposes as if fully set forth herein.
A general schematic view of the WDM architecture 430 is shown on FIG. 3. In the example shown, three applications designated as application #1 431a, application #2 431b, and application #3 431c, are accessing three peripheral hardware devices, designated as peripheral #1 439a, peripheral #2 439b, and peripheral #3 439c. The model involves three layers. The lower layer is the hardware layer 50c, which includes the hardware devices and peripherals, accessed by the processor (such as processor 27) via the hardware bus 430d, which may correspond to internal bus 13 shown in FIG. 1. The highest layer is a ‘user space’ layer 430a, corresponding to the user mode nd to the higher ‘ring’ layers such as Ring 3, and is relating to the space is the memory area where application software and some drivers execute. The kernel of the operating system provides the services as part of a ‘kernel space’ layer 430b, serving as an intermediate layer between the user space layer 430a and the hardware layer 430c. The kernel space 430b operates in a highly privileged hierarchical protection domain, and is strictly reserved for running privileged kernel, kernel extensions, and most device drivers, and is typically corresponding to the kernel mode and to the ‘ring-0’ layer (in x86 processors). The kernel mode may be supported by the processor hardware, or may be supported by a code segment level.
The user mode applications (such as application #1 431a, application #2 431b, and application #3 431c) access the kernel space 430b by the invoking of system calls respectively denoted as connections 432a, 432b and 432c. Typically, such system calls are processed via intermediating entity known as Windows API, such as a Win32 API 433, which access the kernel space 430b via a standard messaging 434. The Win32 API 433 is an example of a Windows API (informally WinAPI), which is Microsoft's core set of Application Programming Interfaces (APIs) available in the Microsoft Windows operating systems. Almost all Windows programs interact with the Windows API; on the Windows NT line of operating systems, a small number (such as programs started early in the Windows startup process) uses the Native API. Supporting for developers is in the form of the Windows Software Development Kit (SDK), providing documentation and tools necessary to build software based upon the Windows API and associated Windows interfaces. The Win32 API 433 is the 32-bit API for modern versions of Windows, and consists of functions implemented, as with Win16, in system DLLs. The core DLLs of the Win32 include the kernel32.dll, user32.dll, and gdi32.dll. The Win32 API is described in the tutorial entitled: “Welcome to Version 2.0 of the Win32 API Tutorial” by Prof. M. Saeed, published by Brook Miles, downloaded from the Internet on July 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
System calls provide an essential interface between a process and the operating system. A system call is how a program requests a service from an operating system's kernel. This may include hardware related services (e.g., accessing the hard disk), creating and executing new processes, and communicating with integral kernel services (such as scheduling). A system call is typically processed in the kernel mode, which is accomplished by changing the processor execution mode to a more privileged one. The hardware sees the world in terms of the execution mode according to the processor status register, and processes are an abstraction provided by the operating system. A system call does not require a context switch to another process, it is processed in the context of whichever process invoked it. The system calls are often executed via traps or interrupts; that automatically puts the CPU into some required privilege level, and then passes control to the kernel, which determines whether the calling program should be granted the requested service. If the service is granted, the kernel executes a specific set of instructions over which the calling program has no direct control, returns the privilege level to that of the calling program, and then returns control to the calling program. Implementing system calls requires a control transfer, which involves some sort of architecture-specific feature.
System calls can be roughly grouped into five major categories: Process control, such as load, execute, create/terminate process, get/set process attributes, wait for time, wait event, and signal event; file management, such as request/release device, create/delete file, open/close file, read/write/reposition file, and get/set file attributes; device management, such as read/write/reposition device, get/set device attributes, and logically attach/detach devices; information maintenance, such as get/set time or date, get/set system data, and get/set process, file, or device attributes; and communication such as create, delete communication connection, transfer status information, and attach or detach remote devices.
The system calls are commonly handled by the I/O manager 435b, which allows devices to communicate with user-mode subsystems. It translates user-mode read and write commands into read or write IRPs which it passes to device drivers. It accepts file system I/O requests and translates them into device specific calls, and can incorporate low-level device drivers that directly manipulate hardware to either read input or write output. It also includes a cache manager to improve disk performance by caching read requests and write to the disk in the background. The I/O manager 435b may interface the power manager 435c, which deals with power events (power-off, stand-by, hibernate, etc.) and notifies affected drivers with special IRPs (Power IRPs).
The PnP manager 435a handles ‘Plug and Play’ and supports device detection and installation at boot time. It also has the responsibility to stop and start devices on demand, that can happen when a bus (such as USB or FireWire) gains a new device and needs to have a device driver loaded to support it. The PnP manager 435a may be partly implemented in user mode, in the Plug and Play Service, which handles the often complex tasks of installing the appropriate drivers, notifying services and applications of the arrival of new devices, and displaying GUI to the user.
I/O Request Packets (IRPs) are kernel mode structures that are used to communicate with each other and with the operating system. They are data structures that describe I/O requests, to a driver, all of these parameters (such as buffer address, buffer size, I/O function type, etc.) are passed via a single pointer to this persistent data structure. The IRP with all of its parameters can be put on a queue if the I/O request cannot be performed immediately. I/O completion is reported back to the I/O manager by passing its address to a routine for that purpose, IoCompleteRequest. The IRP may be repurposed as a special kernel APC object if such is required to report completion of the I/O to the requesting thread. IRPs are typically created by the I/O Manager in response to I/O requests from user mode. However, IRPs are sometimes created by the plug-and-play manager, power manager, and other system components, and can also be created by drivers and then passed to other drivers.
The WDM uses kernel-mode device drivers to enable it to interact with hardware devices, where each of the drivers has well defined system routines and internal routines that it exports to the rest of the operating system. DriverEntry is the first routine called after a driver is loaded, and is responsible for initializing the driver. All devices are seen by user mode code as a file object in the I/O manager, though to the I/O manager itself the devices are seen as device objects, which it defines as either file, device or driver objects. The drivers may be aggregated as a driver stack 436, including kernel mode drivers in three levels: highest level drivers 436a, intermediate drivers 436b, and low level drivers 436c. The highest level drivers 436a, such as file system drivers for FAT and NTFS, rely on the intermediate drivers 436b, which consist of function drivers or main driver for a device, that are optionally sandwiched between lower and higher level filter drivers. The highest level drivers typically know how files are represented on disk, but not the details of how to actually fetch the data, the intermediate level drivers process the requests from the highest level driver by breaking down a large request into a series of small chunks. The function driver commonly possesses the details relating to how the hardware of the peripheral works, typically relies on a bus driver, or a driver that services a bus controller, adapter, or bridge, which can have an optional bus filter driver that sits between itself and the function driver. For example, a PCI bus driver detects the PCI-slot plugged card or hardware, and determines the I/O-mapped or the memory-mapped connection with the host. Intermediate drivers 436b rely on the low level drivers 436c to function. The lowest level drivers 436c are either legacy device drivers that control a device directly, or can be a PnP hardware bus. These lower level drivers 436c directly control hardware and do not rely on any other drivers. The I/O manager 435c communicate with the high-level driver 436a using IRP 437a, the high-level driver 436a communicate with the intermediate level driver 436b using IRP 437b, the intermediate level driver 436b communicate with the low-level driver 436c using IRP 437c, and the low-level driver 436b communicate with the HAL 438 using IRP 437d. 
WDM drivers can be classified into the following types and sub-types: Device function drivers, bus drivers, and filter drivers. A function driver is the main driver for a device. A function driver is typically written by the device vendor and is required (unless the device is being used in raw mode). A function driver can service one or more devices. Miniport drivers are a type of function drivers for interfaces such as USB, audio, SCSI and network adapters. They are hardware specific, but the control access to the hardware is through a specific bus class driver. Class drivers are a type of function drivers and can be thought of as built-in framework drivers that miniport and other class drivers can be built on top of. The class drivers provide interfaces between different levels of the WDM architecture. Common functionality between different classes of drivers can be written into the class driver and used by other class and miniport drivers. The lower edge of the class driver will have its interface exposed to the miniport driver, while the upper edge of top level class drivers is operating system specific. Class drivers can be dynamically loaded and unloaded at will. They can do class specific functions that are not hardware or bus-specific (with the exception of bus-type class drivers) and in fact sometimes only do class specific functions such as enumeration.
A bus driver services a bus controller, adapter, or bridge. Microsoft provides bus drivers for most common buses, such as Advanced configuration and Power Interface (ACPI), Peripheral Component Interconnect (PCI), PnPISA, SCSI, Universal Serial Bus (USB), and FireWire. A bus driver can service more than one bus if there is more than one bus of the same type on the machine. The ACPI bus driver interacts with the ACPI BIOS to enumerate the devices in the system and control their power use, the PCI bus driver (such as pci.sys) enumerates and configures devices connected via the PCI bus, the FireWire and the USB bus driver respectively enumerates and controls devices connected via the IEEE 1394 high speed bus and the USB. The stream class driver provides a basic processing supporting high bandwidth, time critical, and video and audio data related hardware, and uses minidrivers for interfacing the actual hardware, and hard-disk, floppies, CDs, and DVDs are interfaces using SCSI and CDROM/DVD class driver. The Human Input Device (HID) provides an abstract view of input devices, and the Still Image Architecture (SIA) class driver is used to obtain content from a scanner and a still camera, using minidrivers. For example, accessing an hard disk (such as HDD 30) involves a file system driver as high-level driver, a volume manager driver as intermediate level driver, and a disk driver as a low-level driver.
Filter drivers are optional drivers that add value to or modify the behavior of a device and may be non-device drivers. A filter driver can also service one or more devices. Upper level filter drivers sit above the primary driver for the device (the function driver), while lower level filter drivers sit below the function driver and above the bus driver. A driver service is a type of kernel-level filter driver implemented as a Windows service that enables applications to work with devices.
The Hardware Abstraction Layer 438, or HAL, is a layer between the physical hardware layer 430c of the computer and the rest of the operating system. It was designed to hide differences in hardware and therefore provide a consistent platform on which the kernel is run. The HAL 438 includes hardware-specific code that controls I/O interfaces, interrupt controllers and multiple processors. Typically the particular hardware abstraction does not involve abstracting the instruction set, which generally falls under the wider concept of portability. Abstracting the instruction set, when necessary (such as for handling the several revisions to the x86 instruction set, or emulating a missing math coprocessor), is performed by the kernel, or via platform virtualization.
Linux is a Unix-like and mostly POSIX-compliant computer operating system assembled under the model of free and open source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on 5 Oct. 1991 by Linus Torvalds. Linux was originally developed as a free operating system for Intel x86-based personal computers, but has since been ported to more computer hardware platforms than any other operating system. Linux also runs on embedded systems such as mobile phones, tablet computers, network routers, facility automation controls, televisions, and video game consoles. Android, which is a widely used operating system for mobile devices, is built on top of the Linux kernel. Typically, Linux is packaged in a format known as a Linux distribution for desktop and server use.
Linux distributions include the Linux kernel, supporting utilities and libraries and usually a large amount of application software to fulfill the distribution's intended use. A Linux-based system is a modular Unix-like operating system. Such a system uses a monolithic kernel, the Linux kernel, which handles process control, networking, and peripheral and file system access. Device drivers are either integrated directly with the kernel or added as modules loaded while the system is running. Some components of an installed Linux system are a bootloader, for example GNU GRUB or LILO, which is executed by the computer when it is first turned on, and loads the Linux kernel into memory; an init program, which is the first process launched by the Linux kernel, and is at the root of the process tree, and starts processes such as system services and login prompts (whether graphical or in terminal mode); Software libraries which contain code which can be used by running processes; and user interface programs such as command shells or windowing environments. A version of Linux is described, for example, in IBM Corporation (headquartered in Armonk, New-York, U.S.A.) publication No. SC34-2597-03 entitled: “Device Drivers, Features, and Commands on Red Hat Exterprise Linux 6.3”, downloaded from the Internet on July 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
The general schematic Linux driver architecture 450 is shown in FIG. 3a, and the Linux kernel is further described in Wiley Publishing, Inc. publication entitled: “Professional Linux Kernel Architecture”, by Wofgang Mauerer published 2008, and Linux programming is described in the book entitled: “The Linux Kernel Module Programming Guide” ver. 2.6.4 by Peter Jay Salzman, Michael Burian, and Ori Pomerantz, dated May 18, 2007, and in the publication entitled: “A Comparison of the Linux and Windows Device Driver Architecture”, by Melekam Tsegaye and Richard Foss, both from Rhodes University, South-Africa, downloaded from the Internet on July 2014, which are all incorporated in their entirety for all purposes as if fully set forth herein.
Similar to the WDM 430 shown in FIG. 3, the Linux kernel involves a ‘System Call Interface’ 453, receiving system calls 452a, 452b, and 452c from the respective applications such as an application #1 431a, an application #2 431b, and an application #3 431c, and serves as the denomination for the entirety of all implemented and available system calls in a kernel. The Linux kernel is based on a layered modules stack 454, which may include three levels of modules, such as module #1 454a, module #2 454b, and module #3 454c, where the module #1 454a communicate over connection 455a with the system call interface 453, the module #2 454b communicates with the module #1 454a over connection 455b, the module #3 454c communicates over the connection 455c with the module #2 454b and over a connection 455d with the HAL 438.
Similar to the WDM 430 shown in FIG. 3, the Linux kernel shown as the arrangement 450 in FIG. 3a, is using the concept of layered architecture of a modules stack 454, which may comprise module #1 454a, module #2 454b, and module #3 454c, communicating using messaging mechanism, such as a connection 455a between the system call interface 453 and the module #1 454a, a connection 455b between the module #1 454a and the module #2 454b, a connection 455c between the module #2 454b and the module #3 454c, and a connection 455d between the module #3 454c and the HAL 438.
The modules in the modules stack 454, typically referred to as Loadable Kernel Modules (or LKM), are object files that contain code to extend the running Linux kernel, or so-called base kernel. LKMs are typically used to add support for new hardware and/or filesystems, or for adding system calls. When the functionality provided by a LKM is no longer required, it can be unloaded in order to free memory and other resources. Loadable kernel modules in Linux are located in /lib/modules and have had the extension ‘.ko’ (“kernel object”) since version 2.6 (previous versions used the .o extension), and are loaded (and unloaded) by the modprobe command. The lsmod command lists the loaded kernel modules. In emergency cases, when the system fails to boot (due to e.g. broken modules), specific modules can be enabled or disabled by modifying the kernel boot parameters list (for example, if using GRUB, by pressing ‘e’ in the GRUB start menu, then editing the kernel parameter line). Linux allows disabling module loading via sysctl option /proc/sys/kernel/modules_disabled. An initramfs system may load specific modules needed for a machine at boot and then disable module loading.
A web browser (commonly referred to as a browser) is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier (URI/URL) and may be part of a web page, a web-page, an image, a video, or any other piece of content. Hyperlinks present in resources enable users easily to navigate their browsers to related resources. Although browsers are primarily intended to use the World Wide Web, they can also be used to access information provided by web servers in private networks or files in file systems. The primary purpose of a web browser is to bring information resources to the user (“retrieval” or “fetching”), allowing them to view the information (“display”, “rendering”), and then access other information (“navigation”, “following links”). Currently the major web browsers are known as Firefox, Internet Explorer, Google Chrome, Opera, and Safari.
The process begins when the user inputs a Uniform Resource Locator (URL), for example ‘http://en.wikipedia.org/’, into the browser. The prefix of the URL, the Uniform Resource Identifier or URI, determines how the URL will be interpreted. The most commonly used kind of URI starts with http: and identifies a resource to be retrieved over the Hypertext Transfer Protocol (HTTP). Many browsers also support a variety of other prefixes, such as https: for HTTPS, ftp: for the File Transfer Protocol, and file: for local files. Prefixes that the web browser cannot directly handle are often handed off to another application entirely. For example, mailto: URIs are usually passed to the user's default e-mail application, and news: URIs are passed to the user's default newsgroup reader. In the case of http, https, file, and others, once the resource has been retrieved the web browser will display it. HTML and associated content (image files, formatting information such as CSS, etc.) is passed to the browser's layout engine to be transformed from markup to an interactive document, a process known as “rendering”. Aside from HTML, web browsers can generally display any kind of content that can be part of a web page. Most browsers can display images, audio, video, and XML files, and often have plug-ins to support Flash applications and Java applets. Upon encountering a file of an unsupported type or a file that is set up to be downloaded rather than displayed, the browser prompts the user to save the file to disk. Information resources may contain hyperlinks to other information resources. Each link contains the URI of a resource to go to. When a link is clicked, the browser navigates to the resource indicated by the link's target URI, and the process of bringing content to the user begins again. The architecture of a web browser is described in the publication entitled: “Architecture and evolution of the modern web browser” by Alan Grosskurth and Michael W. Godfrey of the University of Waterloo in Canada, dated Jun. 20, 2006, which is incorporated in its entirety for all purposes as if fully set forth herein.
A currently popular web browser is the Internet Explorer (formerly Microsoft Internet Explorer and Windows Internet Explorer, commonly abbreviated IE or MSIE) from Microsoft Corporation, headquartered in Redmond, Wash., U.S.A., which is a series of graphical web browsers developed by Microsoft and included as part of the Microsoft Windows line of operating systems. The Internet Explorer 8 is described, for example, in Microsoft 2009 publication entitled: “Step by Step Tutorials for Microsoft Internet Explorer 8 Accessibility Options”, which is incorporated in its entirety for all purposes as if fully set forth herein. Another popular web browser is the Google Chrome which is a freeware web browser developed by Google, heagquartered in Googleplex, Mountain View, Calif., U.S.A. Google Chrome aims to be secure, fast, simple, and stable, providing strong application performance and JavaScript processing speed.
A mobile browser, also called a microbrowser, minibrowser, or Wireless Internet Browser (WIB), is a web browser designed for use on a mobile device such as a mobile phone or PDA. Mobile browsers are optimized so as to display Web content most effectively for small screens on portable devices. Mobile browser software must be small and efficient to accommodate the low memory capacity and low-bandwidth of wireless handheld devices. Some mobile browsers can handle more recent technologies like CSS 2.1, JavaScript, and Ajax. Websites designed for access from these browsers are referred to as wireless portals or collectively as the Mobile Web. They may automatically create “mobile” versions of each page, for example this one
The mobile browser typically connects via cellular network, via Wireless LAN, or via other wireless networks, and are using standard HTTP over TCP/IP, and displays web pages written in HTML, XHTML Mobile Profile (WAP 2.0), or WML (which evolved from HDML). WML and HDML are stripped-down formats suitable for transmission across limited bandwidth, and wireless data connection called WAP. WAP 2.0 specifies XHTML Mobile Profile plus WAP CSS, subsets of the W3C's standard XHTML and CSS with minor mobile extensions. Some mobile browsers are full-featured Web browsers capable of HTML, CSS, ECMAScript, as well as mobile technologies such as WML, i-mode HTML, or cHTML. To accommodate small screens, some mobile browsers use Post-WIMP interfaces. An example of a mobile browser is Safari, which is a mobile web browser developed by Apple Inc. (headquartered in Apple Campus, Cupertino, Calif., U.S.A), included with the OS X and iOS operating systems, and described in Apple publication entitled: “Safari Web Content Guide”, dated March 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
FIG. 1 shows a block diagram that illustrates a system 10 including a computer system 11 and the associated Internet 113 connection. Such configuration is typically used for computers (hosts) connected to the Internet 113 and executing a server or a client (or a combination) software. The system 11 may be used as a portable electronic device such as a notebook/laptop computer, a media player (e.g., MP3 based or video player), a desktop computer, a laptop computer, a cellular phone, a Personal Digital Assistant (PDA), an image processing device (e.g., a digital camera or video recorder), and/or any other handheld or fixed location computing devices, or a combination of any of these devices. Note that while FIG. 1 illustrates various components of a computer system, it is not intended to represent any particular architecture or manner of interconnecting the components; as such details are not germane. It will also be appreciated that network computers, handheld computers, cell phones and other data processing systems which have fewer components or perhaps more components may also be used. The computer system of FIG. 1 may, for example, be an Apple Macintosh computer or Power Book, or an IBM compatible PC. The computer system 11 includes a bus 13, an interconnect, or other communication mechanism for communicating information, and a processor 27, commonly in the form of an integrated circuit, coupled to the bus 13 for processing information and for executing the computer executable instructions. Computer system 11 also includes a main memory 122, such as a Random Access Memory (RAM) or other dynamic storage device, coupled to bus 13 for storing information and instructions to be executed by processor 27. Main memory 122 also may be used for storing temporary variables or other intermediate information during execution of instructions to be executed by processor 27. The computer system 11 further includes a Read Only Memory (ROM) 25b (or other non-volatile memory) or other static storage device coupled to the bus 13 for storing static information and instructions for the processor 27. A storage device 25c, such as a magnetic disk or optical disk, a hard disk drive (HDD) for reading from and writing to a hard disk, a magnetic disk drive for reading from and writing to a magnetic disk, and/or an optical disk drive (such as DVD) for reading from and writing to a removable optical disk, is coupled to bus 13 for storing information and instructions. The hard disk drive, magnetic disk drive, and optical disk drive may be connected to the system bus by a hard disk drive interface, a magnetic disk drive interface, and an optical disk drive interface, respectively. The drives and their associated computer-readable media provide non-volatile storage of computer readable instructions, data structures, program modules and other data for the general purpose computing devices. Typically, the computer system 11 includes an Operating System (OS) stored in a non-volatile storage for managing the computer resources and provides the applications and programs with an access to the computer resources and interfaces. An operating system commonly processes system data and user input, and responds by allocating and managing tasks and internal system resources, such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating networking and managing files. Non-limiting examples of operating systems are Microsoft Windows, Mac OS X, and Linux.
The term “processor” is used herein to include, but not limited to, any integrated circuit or other electronic device (or collection of devices) capable of performing an operation on at least one instruction, including, without limitation, Reduced Instruction Set Core (RISC) processors, CISC microprocessors, Microcontroller Units (MCUs), CISC-based Central Processing Units (CPUs), and Digital Signal Processors (DSPs). The hardware of such devices may be integrated onto a single substrate (e.g., silicon “die”), or distributed among two or more substrates. Furthermore, various functional aspects of the processor may be implemented solely as software or firmware associated with the processor.
The computer system 11 may be coupled via a bus 13 to a display 17, such as a Cathode Ray Tube (CRT), a Liquid Crystal Display (LCD), a flat screen monitor, a touch screen monitor or similar means for displaying text and graphical data to a user. The display may be connected via a video adapter for supporting the display. The display allows a user to view, enter, and/or edit information that is relevant to the operation of the system. An input device 18, including alphanumeric and other keys, is coupled to the bus 13 for communicating information and command selections to the processor 27. Another type of user input device is a cursor control 19, such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to the processor 27 and for controlling cursor movement on the display 17. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane.
The computer system 11 may be used for implementing the methods and techniques described herein. According to one embodiment, those methods and techniques are performed by the computer system 11 in response to the processor 27 executing one or more sequences of one or more instructions contained in a main memory 25a. Such instructions may be read into the main memory 25a from another computer-readable medium, such as a storage device 123. Execution of the sequences of instructions contained in the main memory 25a causes the processor 27 to perform the process steps described herein. In alternative embodiments, hard-wired circuitry may be used in place of or in combination with software instructions to implement the arrangement. Thus, embodiments of the invention are not limited to any specific combination of hardware circuitry and software.
The term “computer-readable medium” (or “machine-readable medium”) is used herein to include, but not limited to, any medium or any memory, that participates in providing instructions to a processor, (such as the processor 27) for execution, or any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computer). Such a medium may store computer-executable instructions to be executed by a processing element and/or control logic, and data which is manipulated by a processing element and/or control logic, and may take many forms, including but not limited to, non-volatile medium, volatile medium, and transmission medium. Transmission media includes coaxial cables, copper wire and fiber optics, including the wires that comprise the bus 13. Transmission media can also take the form of acoustic or light waves, such as those generated during radio-wave and infrared data communications, or other form of propagating signals (e.g., carrier waves, infrared signals, digital signals, etc.). Common forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, or any other magnetic medium, a CD-ROM, any other optical medium, punch-cards, paper-tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave as described hereinafter, or any other medium from which a computer can read.
Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to to processor 27 for execution. For example, the instructions may initially be carried on a magnetic disk of a remote computer. The remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to the computer system 11 can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal. An infrared detector can receive the data carried in the infrared signal and appropriate circuitry can place the data on the bus 13. The bus 13 carries the data to the main memory 25a, from which the processor 27 retrieves and executes the instructions. The instructions received by the main memory 25a may optionally be stored on the storage device 25c either before or after execution by the processor 27.
The computer system 11 commonly includes a communication interface 29 coupled to the bus 13. The communication interface 29 provides a two-way data communication coupling to a network link 28 that is connected to a local network 14. For example, the communication interface 29 may be an Integrated Services Digital Network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another non-limiting example, the communication interface 29 may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. For example, Ethernet based connection based on IEEE802.3 standard may be used, such as 10/100BaseT, 1000BaseT (gigabit Ethernet), 10 gigabit Ethernet (10GE or 10 GbE or 10 GigE per IEEE Std. 802.3ae-2002as standard), 40 Gigabit Ethernet (40 GbE), or 100 Gigabit Ethernet (100 GbE as per Ethernet standard IEEE P802.3ba). These technologies are described in Cisco Systems, Inc. Publication number 1-587005-001-3 (June 1999), “Internetworking Technologies Handbook”, Chapter 7: “Ethernet Technologies”, pages 7-1 to 7-38, which is incorporated in its entirety for all purposes as if fully set forth herein. In such a case, the communication interface 29 typically includes a LAN transceiver or a modem, such as Standard Microsystems Corporation (SMSC) LAN91C111 10/100 Ethernet transceiver, described in a Standard Microsystems Corporation (SMSC) data-sheet “LAN91C111 10/100 Non-PCI Ethernet Single Chip MAC+PHY” Data-Sheet, Rev. 15 (Feb. 20, 2004), which is incorporated in its entirety for all purposes as if fully set forth herein.
The Internet 113 is a global system of interconnected computer networks that use the standardized Internet Protocol Suite (TCP/IP), including Transmission Control Protocol (TCP) and the Internet Protocol (IP), to serve billions of users worldwide. It is a network of networks that consists of millions of private, public, academic, business, and government networks, of local to global scope, that are linked by a broad array of electronic and optical networking technologies. The Internet carries a vast range of information resources and services, such as the interlinked hypertext documents on the World Wide Web (WWW) and the infrastructure to support electronic mail. The Internet backbone refers to the principal data routes between large, strategically interconnected networks and core routers in the Internet. These data routes are hosted by commercial, government, academic and other high-capacity network centers, the Internet exchange points and network access points that interchange Internet traffic between the countries, continents and across the oceans of the world. Traffic interchange between Internet service providers (often Tier 1 networks) participating in the Internet backbone exchange traffic by privately negotiated interconnection agreements, primarily governed by the principle of settlement-free peering.
An Internet Service Provider (ISP) 12 is an organization that provides services for accessing, using, or participating in the Internet 113. Internet Service Providers may be organized in various forms, such as commercial, community-owned, non-profit, or otherwise privately owned. Internet services typically provided by ISPs include Internet access, Internet transit, domain name registration, web hosting, and colocation. Various ISP Structures are described in Chapter 2: “Structural Overview of ISP Networks” of the book entitled: “Guide to Reliable Internet Services and Applications”, by Robert D. Doverspike, K. K. Ramakrishnan, and Chris Chase, published 2010 (ISBN: 978-1-84882-827-8), which is incorporated in its entirety for all purposes as if fully set forth herein.
A mailbox provider is an organization that provides services for hosting electronic mail domains with access to storage for mailboxes. It provides email servers to send, receive, accept, and store email for end users or other organizations. Internet hosting services provide email, web-hosting, or online storage services. Other services include virtual server, cloud services, or physical server operation. A virtual ISP (VISP) is an operation that purchases services from another ISP, sometimes called a wholesale ISP in this context, which allow the VISP's customers to access the Internet using services and infrastructure owned and operated by the wholesale ISP. It is akin to mobile virtual network operators and competitive local exchange carriers for voice communications. A Wireless Internet Service Provider (WISP) is an Internet service provider with a network based on wireless networking. Technology may include commonplace Wi-Fi wireless mesh networking, or proprietary equipment designed to operate over open 900 MHz, 2.4 GHz, 4.9, 5.2, 5.4, 5.7, and 5.8 GHz bands or licensed frequencies in the UHF band (including the MMDS frequency band) and LMDS.
ISPs may engage in peering, where multiple ISPs interconnect at peering points or Internet exchange points (IXs), allowing routing of data between each network, without charging one another for the data transmitted—data that would otherwise have passed through a third upstream ISP, incurring charges from the upstream ISP. ISPs requiring no upstream and having only customers (end customers and/or peer ISPs), are referred to as Tier 1 ISPs.
A multitasking is a method where multiple tasks (also known as processes or programs) are performed during the same period of time—they are executed concurrently (in overlapping time periods, new tasks starting before others have ended) instead of sequentially (one completing before the next starts). The tasks share common processing resources, such as a CPU and main memory. Multitasking does not necessarily mean that multiple tasks are executing at exactly the same instant. In other words, multitasking does not imply parallelism, but it does mean that more than one task can be part-way through execution at the same time, and more than one task is advancing over a given period of time.
In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is actively executing instructions for that task. Multitasking solves the problem by scheduling which task may be the one running at any given time, and when another waiting task gets a turn. The act of reassigning a CPU from one task to another one is called a context switch. When context switches occur frequently enough, the illusion of parallelism is achieved. Even on computers with more than one CPU (called multiprocessor machines) or more than one core in a given CPU (called multicore machines), where more than one task can be executed at a given instant (one per CPU or core), multitasking allows many more tasks to be run than there are CPUs.
Operating systems may adopt one of many different scheduling strategies. In multiprogramming systems, the running task keeps running until it performs an operation that requires waiting for an external event (e.g. reading from a tape) or until the computer's scheduler forcibly swaps the running task out of the CPU. Multiprogramming systems are designed to maximize CPU usage. In time-sharing systems, the running task is required to relinquish the CPU, either voluntarily or by an external event such as a hardware interrupt. Time sharing systems are designed to allow several programs to execute apparently simultaneously. In real-time systems, some waiting tasks are guaranteed to be given the CPU when an external event occurs. Real time systems are designed to control mechanical devices such as industrial robots, which require timely processing.
Encryption based mechanisms are commonly end-to-end processes involving only the sender and the receiver, where the sender encrypts the plain text message by transforming it using an algorithm, making it unreadable to anyone, except the receiver which possesses special knowledge. The data is then sent to the receiver over a network such as the Internet, and when received the special knowledge enables the receiver to reverse the process (decrypt) to make the information readable as in the original message. The encryption process commonly involves computing resources such as processing power, storage space and requires time for executing the encryption/decryption algorithm, which may delay the delivery of the message.
Transport Layer Security (TLS) and its predecessor Secure Sockets Layer (SSL) are non-limiting examples of end-to-end cryptographic protocols, providing secured communication above the OSI Transport Layer, using keyed message authentication code and symmetric cryptography. In client/server applications, the TLS client and server negotiate a stateful connection by using a handshake procedure, during which various parameters are agreed upon, allowing a communication in a way designed to prevent eavesdropping and tampering. The TLS 1.2 is defined in RFC 5246, and several versions of the protocol are in widespread use in applications such as web browsing, electronic mail, Internet faxing, instant messaging and Voice-over-IP (VoIP). In application design, TLS is usually implemented on top of any of the Transport Layer protocols, encapsulating the application-specific protocols such as HTTP, FTP, SMTP, NNTP, and XMPP. Historically, it has been used primarily with reliable transport protocols such as the Transmission Control Protocol (TCP). However, it has also been implemented with datagram-oriented transport protocols, such as the User Datagram Protocol (UDP) and the Datagram Congestion Control Protocol (DCCP), a usage which has been standardized independently using the term Datagram Transport Layer Security (DTLS). A prominent use of TLS is for securing World Wide Web traffic carried by HTTP to form HTTPS. Notable applications are electronic commerce and asset management. Increasingly, the Simple Mail Transfer Protocol (SMTP) is also protected by TLS (RFC 3207). These applications use public key certificates to verify the identity of endpoints. Another Layer 4 (Transport Layer) and upper layers encryption-based communication protocols include SSH (Secure Shell) and SSL (Secure Socket Layer).
Layer 3 (Network Layer) and lower layer encryption based protocols include IPsec, L2TP (Layer 2 Tunneling Protocol) over IPsec, and Ethernet over IPsec. The IPsec is a protocol suite for securing IP communication by encrypting and authenticating each IP packet of a communication session. The IPsec standard is currently based on RFC 4301 and RFC 4309, and was originally described in RFCs 1825-1829, which are now obsolete, and uses the Security Parameter Index (SPI, as per RFC 2401) as an identification tag added to the header while using IPsec for tunneling the IP traffic. An IPsec overview is provided in Cisco Systems, Inc. document entitled: “An Introduction to IP Security (IPSec) Encryption”, which is incorporated in its entirety for all purposes as if fully set forth herein.
Two common approaches to cryptography are found in U.S. Pat. No. 3,962,539 to Ehrsam et al., entitled “Product Block Cipher System for Data Security”, and in U.S. Pat. No. 4,405,829 to Rivest et al., entitled “Cryptographic Communications System and Method”, which are both incorporated in their entirety for all purposes as if fully set forth herein. The Ehrsam patent discloses what is commonly known as the Data Encryption Standard (DES), while the Rivest patent discloses what is commonly known as the RSA algorithm (which stands for Rivest, Shamir and Adleman who first publicly described it), which is widely used in electronic commerce protocols. The RSA involves using a public key and a private key. DES is based upon secret-key cryptography, also referred to as symmetric cryptography, and relies upon a 56-bit key for encryption. In this form of cryptography, the sender and receiver of cipher text both possess identical secret keys, which are, in an ideal world, completely unique and unknown to the world outside of the sender and receiver. By encoding plain text into cipher text using the secret key, the sender may send the cipher text to the receiver using any available public or otherwise insecure communication system. The receiver, having received the cipher text, decrypts it using the secret key to arrive at the plain text.
A proxy server is a server (a computer system or an application) that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server and the proxy server evaluates the request as a way to simplify and control its complexity. Proxies may be used to add structure and encapsulation to distributed systems. Today, most proxies are web proxies, facilitating access to content on the World Wide Web and providing anonymity. A proxy server may reside on the user's local computer, or at various points between the user's computer and destination servers on the Internet. A proxy server that passes requests and responses unmodified is usually called a gateway or sometimes a tunneling proxy. A forward proxy is an Internet-facing proxy used to retrieve from a wide range of sources (in most cases anywhere on the Internet). Forward proxies are proxies in which the client server names the target server to connect to, and are able to retrieve from a wide range of sources (in most cases anywhere on the Internet). An open proxy is a forwarding proxy server that is accessible by any Internet user, while browsing the Web or using other Internet services. There are varying degrees of anonymity, however, as well as a number of methods of ‘tricking’ the client into revealing itself regardless of the proxy being used. A reverse proxy is usually an Internet-facing proxy used as a front-end to control and protect access to a server on a private network. A reverse proxy commonly also performs tasks such as load-balancing, authentication, decryption or caching.
Randomness is commonly implemented by using random numbers, defined as a sequence of numbers or symbols that lack any pattern and thus appear random, are often generated by a random number generator. Randomness for security is also described in IETF RFC 1750 “Randomness Recommendations for Security” (December 1994), which is incorporated in its entirety for all purposes as if fully set forth herein. A random number generator (having either analog or digital output) can be hardware based, using a physical process such as thermal noise, shot noise, nuclear decaying radiation, photoelectric effect or other quantum phenomena. Alternatively, or in addition, the generation of the random numbers can be software based, using a processor executing an algorithm for generating pseudo-random numbers which approximates the properties of random numbers.
Onion routing (OR) is a technique for anonymous communication over the Internet or any other computer network. Messages are repeatedly encrypted and then sent through several network nodes called onion routers. Each onion router removes a layer of encryption to uncover routing instructions, and sends the message to the next router where this is repeated. This prevents these intermediary nodes from knowing the origin, destination, and contents of the message. To prevent an adversary from eavesdropping on message content, messages are encrypted between routers. The advantage of onion routing (and mix cascades in general) is that it is not necessary to trust each cooperating router; if one or more routers are compromised, anonymous communication can still be achieved. This is because each router in an OR network accepts messages, re-encrypts them, and transmits to another onion router. The idea of onion routing (OR) is to protect the privacy of the sender and the recipient of a message, while also providing protection for message content as it traverses a network. Onion routing accomplishes this according to the principle of Chaum mix cascades: messages travel from source to destination via a sequence of proxies (“onion routers”), which re-route messages in an unpredictable path.
Routing onions are data structures used to create paths through which many messages can be transmitted. To create an onion, the router at the head of a transmission selects a number of onion routers at random and generates a message for each one, providing it with symmetric keys for decrypting messages, and instructing it which router will be next in the path. Each of these messages, and the messages intended for subsequent routers, is encrypted with the corresponding router's public key. This provides a layered structure, in which it is necessary to decrypt all outer layers of the onion in order to reach an inner layer. Onion routing is described in U.S. Pat. No. 6,266,704 to Reed et al., entitled: “Onion Routing Network for Securely Moving data through Communication Networks”, which is incorporated in its entirety for all purposes as if fully set forth herein. Other prior art publications relating to onion routing are the publications “Probabilistic Analysis of Onion Routing in a Black-box Model [Extended Abstract]” presented in WPES '07: Proceedings of the 2007 ACM Workshop on Privacy in Electronic Society, “A Model of Onion Routing with Provable Anonymity” presented in Proceedings of Financial Cryptography and Data Security '07, and “A Model of Onion Routing with Provable Anonymity”, presented in the Financial Cryptography and Data Security, 11th International Conference, all by Feigenbaum J., Johnson J. and Syverson P., publications “Improving Efficiency and Simplicity of Tor circuit establishment and hidden services”, Proceedings of the 2007 Privacy Enhancing Technologies Symposium, Springer-Verlag, LNCS 4776, publication “Untraceable electronic mail, return addresses, and digital pseudonyms” by Chaum D., in Communications of the ACM 24(2), February 1981, and “Valet Services: Improving Hidden Servers with a Personal Touch”, Proceedings of the 2006 Privacy Enhancing Technologies Workshop, Springer-Verlag, LNCS 4285, both by Overlier L., Syverson P., publications “Making Anonymous Communication”, Generation 2 Onion Routing briefing slides, Center for High Assurance Computer Systems, naval Research Laboratory, Presented at the National Science Foundation, Jun. 8, 2004 by Syverson P., publications “Onion Routing Access Configurations, DISCEX 2000: Proceedings of the DARPA Information Survivability Conference and Exposition”, Volume I Hilton Head, S.C., IEEE CS Press, January 2000, “Onion Routing for Anonymous and Private Internet Connections” Communications of the ACM, vol. 42, num. 2, February 1999, and “Anonymous Connections and Onion Routing” IEEE Journal on Selected Areas in Communication Special Issue on Copyright and Privacy Protection, 1998, all by Syverson P., Reed M. G., Goldschlag M., publication “Towards an Analysis of Onion Routing Security”, and “Workshop on Design Issues in Anonymity and Unobservability”, Berkeley, Calif., July 2000 by Syverson P., Tsudik G., Reed M. G., and Landwehr C, which are incorporated in their entirety for all purposes as if fully set forth herein.
‘Tor’ is an anonymizing network based on the principles of ‘onion routing’, and involves a system which selects a randomly chosen route for each connection, via the routers present in the Tor network. The last server appears herein as an ‘exit node’ and sends the data to the final recipient after leaving the Tor cloud. At this point, it is no longer possible for an observer constantly watching the ‘exit node’ to determine who the sender of the message was. This concept and its components are known from the ‘Tor’ project in http://www.torproject.org. The Tor network concept is described in U.S. Patent Application Publication 2010/0002882 to Rieger et al., in the publication “Tor: The Second-Generation Onion Router”, in Proceedings of the 13th USENIX Security Symposium August 2004, by Dingledine R., Mathewson N., Syverson P., in the publication “Tor Protocol specification” by Dingledine R. and Mathewson N., in the publication “Tor Directory Protocol, Version 3”, and the publication “TC: A Tor Control Protocol” downloaded from the Tor web-site, which are incorporated in their entirety for all purposes as if fully set forth herein.
Computer networks may use a tunneling protocol where one network protocol (the delivery protocol) encapsulates a different payload protocol. Tunneling enables the encapsulation of a packet from one type of protocol within the datagram of a different protocol. For example, VPN uses PPTP to encapsulate IP packets over a public network, such as the Internet. A VPN solution based on Point-to-Point Tunneling Protocol (PPTP), Layer Two Tunneling Protocol (L2TP), or Secure Socket Tunneling Protocol (SSTP) can be configured. By using tunneling a payload may be carried over an incompatible delivery-network, or provide a secure path through an untrusted network. Typically, the delivery protocol operates at an equal or higher OSI layer than does the payload protocol. In one example of a network layer over a network layer, Generic Routing Encapsulation (GRE), a protocol running over IP (IP Protocol Number 47), often serves to carry IP packets, with RFC 1918 private addresses, over the Internet using delivery packets with public IP addresses. In this case, the delivery and payload protocols are compatible, but the payload addresses are incompatible with those of the delivery network. In contrast, an IP payload might believe it sees a data link layer delivery when it is carried inside the Layer 2 Tunneling Protocol (L2TP), which appears to the payload mechanism as a protocol of the data link layer. L2TP, however, actually runs over the transport layer using User Datagram Protocol (UDP) over IP. The IP in the delivery protocol could run over any data-link protocol from IEEE 802.2 over IEEE 802.3 (i.e., standards-based Ethernet) to the Point-to-Point Protocol (PPP) over a dialup modem link.
Tunneling protocols may use data encryption to transport insecure payload protocols over a public network (such as the Internet), thereby providing VPN functionality. IPsec has an end-to-end Transport Mode, but can also operate in a tunneling mode through a trusted security gateway. HTTP tunneling is a technique by which communications performed using various network protocols are encapsulated using the HTTP protocol, the network protocols in question usually belonging to the TCP/IP family of protocols. The HTTP protocol therefore acts as a wrapper for a channel that the network protocol being tunneled uses to communicate. The HTTP stream with its covert channel is termed an HTTP tunnel. HTTP tunnel software consists of client-server HTTP tunneling applications that integrate with existing application software, permitting them to be used in conditions of restricted network connectivity including firewalled networks, networks behind proxy servers, and network address translation.
Virtual Private Networks (VPNs) are point-to-point connections across a private or public network, such as the Internet. A VPN client typically uses special TCP/IP-based protocols, called tunneling protocols, to make a virtual call to a virtual port on a VPN server. In a typical VPN deployment, a client initiates a virtual point-to-point connection to a remote access server over the Internet, then the remote access server answers the call, authenticates the caller, and transfers data between the VPN client and the organization's private network. To emulate a point-to-point link, data is encapsulated, or wrapped, with a header. The header provides routing information that enables the data to traverse the shared or public network to reach its endpoint. To emulate a private link, the data being sent is encrypted for confidentiality. Packets that are intercepted on the shared or public network are indecipherable without the encryption keys. The link in which the private data is encapsulated and encrypted is known as a VPN connection. Commonly there are two types of VPN connections, referred to as Remote Access VPN and Site-to-Site VPN. Popular VPN connections use PPTP, L2TP/IPsec, or SSTP protocols. The RFC 4026 provides ‘Provider Provisioned Virtual Private Network (VPN) Terminology’, and RFC 2547 provides a VPN method based on MPLS (Multiprotocol Label Switching) and BGP (Border Gateway Protocol).
Remote access VPN connections enable users working at home or on the road to access a server on a private network using the infrastructure provided by a public network, such as the Internet. From the user's perspective, the VPN is a point-to-point connection between the computer (the VPN client) and an organization's server. The exact infrastructure of the shared or public network is irrelevant because it appears logically as if the data is sent over a dedicated private link.
Site-to-site VPN connections (also known as router-to-router VPN connections) enable organizations to have routed connections between separate offices or with other organizations over a public network while helping to maintain secure communications. A routed VPN connection across the Internet logically operates as a dedicated wide area network (WAN) link. When networks are connected over the Internet, a router forwards packets to another router across a VPN connection. To the routers, the VPN connection operates as a data-link layer link. A site-to-site VPN connection connects two portions of a private network. The VPN server provides a routed connection to the network to which the VPN server is attached. The calling router (the VPN client) authenticates itself to the answering router (the VPN server), and, for mutual authentication, the answering router authenticates itself to the calling router. In the site-to site VPN connection, the packets sent from either router across the VPN connection typically do not originate at the routers.
There is a growing widespread use of the Internet for carrying multimedia, such as a video and audio. Various audio services include Internet-radio stations and VoIP (Voice-over-IP). Video services over the Internet include video conferencing and IPTV (IP Television). In most cases, the multimedia service is a real-time (or near real-time) application, and thus sensitive to delays over the Internet. In particular, two-way services such a VoIP or other telephony services and video-conferencing are delay sensitive. In some cases, the delays induced by the encryption process, as well as the hardware/software costs associated with the encryption, render encryption as non-practical. Therefore, it is not easy to secure enough capacity of the Internet accessible by users to endure real-time communication applications such as Internet games, chatting, VoIP, and MoIP (Multimedia-over-IP), so there may be a data loss, delay or severe jitter in the course of communication due to the property of an Internet protocol, thereby causing inappropriate real-time video communication. The following chapters of the publication number 1-587005-001-3 by Cisco Systems, Inc. (July 1999), entitled: “Internetworking Technologies Handbook”, relate to multimedia carried over the Internet, and are all incorporated in their entirety for all purposes as if fully set forth herein: Chapter 18: “Multiservice Access Technologies” (pages 18-1 to 18-10), and Chapter 19: “Voice/Data Integration Technologies” (pages 19-1 to 19-30).
VoIP systems in widespread use today fall into three groups: systems using the ITU-T H.323 protocol, systems using the SIP protocol, and systems that use proprietary protocols. H.323 is a standard for teleconferencing that was developed by the International Telecommunications Union (ITU). It supports full multimedia, audio, video and data transmission between groups of two or more participants, and it is designed to support large networks. H.323 is network-independent: it can be used over networks using transport protocols other than TCP/IP. H.323 is still a very important protocol, but it has fallen out of use for consumer VoIP products due to the fact that it is difficult to make it work through firewalls that are designed to protect computers running many different applications. It is a system best suited to large organizations that possess the technical skills to overcome these problems.
Session Initiation Protocol (SIP) is an Internet Engineering Task Force (IETF) standard signaling protocol for teleconferencing, telephony, presence and event notification and instant messaging. It provides a mechanism for setting up and managing connections, but not for transporting the audio or video data. It is probably now the most widely used protocol for managing Internet telephony. Similar to the IETF protocols, SIP is defined in a number of RFCs, principally RFC 3261. A SIP-based VoIP implementation may send the encoded voice data over the network in a number of ways. Most implementations use a Real-time Transport Protocol (RTP), which is defined in RFC 3550. Both SIP and RTP are implemented on UDP, which, as a connectionless protocol, can cause difficulties with certain types of routers and firewalls. Usable SIP phones therefore also need to use Simple Traversal of UDP over NAT (STUN), a protocol defined in RFC 3489 that allows a client behind a NAT router to find out its external IP address and the type of NAT device.
FIG. 2 shows arrangement 20 of devices communicating over the Internet. Various devices such as client #1 24a, client #2 24b, client #3 24c, client #4 24d, and client #5 24e, may communicate over the Internet 113 for obtaining data from a data server #1 22a and a data server #2 22b. In one example, the servers are HTTP servers, sometimes known as web servers. A method describing a more efficient communication over the Internet is described in U.S. Pat. No. 8,560,604 to Shribman et al., entitled: “System and Method for Providing Faster and More Efficient Data Communication” (hereinafter the “‘604 Patent’”), which is incorporated in its entirety for all purposes as if fully set forth herein. The method described in the '604 Patent uses an acceleration server 32 for managing the traffic in the network, as shown in FIG. 2. A splitting of a message or a content into slices, and transferring each of the slices over a distinct data path is described in U.S. Patent Application No. 2012/0166582 to Binder entitled: “System and Method for Routing-Based Internet Security”, which is incorporated in its entirety for all purposes as if fully set forth herein.
A Cyclic Redundancy Check (CRC) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data. Blocks of data entering these systems get a short check value attached, based on the remainder of a polynomial division of their contents; on retrieval the calculation is repeated, and corrective action can be taken against presumed data corruption if the check values do not match. Ethernet commonly uses 32-bit CRC function. Specification of a CRC code requires definition of a so-called generator polynomial. The polynomial becomes a divisor in a polynomial long division, which takes the message as the dividend, and in which the quotient is discarded and the remainder becomes the result. The important caveat that the polynomial coefficients are calculated according to the arithmetic of a finite field, so the addition operation can always be performed bitwise-parallel (there is no carry between digits). The length of the remainder is always less than the length of the generator polynomial, which therefore determines how long the result can be. In practice, all commonly used CRCs employ the finite field GF(2). This is the field of two elements, usually called 0 and 1, comfortably matching computer architecture.
A CRC is referred to as an n-bit CRC when its check value is n bits. For a given n, multiple CRCs are possible, each with a different polynomial. Such a polynomial has highest degree n, which means it has n+1 terms. In other words, the polynomial has a length of n+1; its encoding requires n+1 bits. Note that most integer encodings either drop the Most Significant Bit (MSB) or Least Significant Bit (LSB), since they are always 1. The CRC and associated polynomial typically have a name of the form CRC-n-XXX. The simplest error-detection system, the parity bit, is in fact a trivial 1-bit CRC: it uses the generator polynomial x+1 (two terms), and has the name CRC-1. Computation of a cyclic redundancy check is derived from the mathematics of polynomial division, modulo two. In practice, it resembles long division of the binary message string, with a fixed number of zeroes appended, by the “generator polynomial” string except that exclusive OR operations replace subtractions. Division of this type is efficiently realised in hardware by a modified shift register and in software by a series of equivalent algorithms, starting with simple code close to the mathematics and becoming faster through byte-wise parallelism and space-time tradeoffs.
Various CRC standards extend the polynomial division algorithm by specifying an initial shift register value, a final exclusive OR step and, most critically, a bit ordering (endianness). As a result, the code seen in practice deviates confusingly from “pure” division, and the register may shift left or right. The most important attribute of the polynomial is its length (largest degree—exponent-+1 of any one term in the polynomial), because of its direct influence on the length of the computed check value. The most commonly used polynomial lengths are 9 bits (CRC-8), 17 bits (CRC-16), 33 bits (CRC-32), and 65 bits (CRC-64). A calculation of CRC-32 is described in the publication entitled: “32-Bit Cyclic Redundancy Codes for Internet Applications” by Philip Koopman of Carnegie Mellon University, presented at The International Conference on Dependable Systems and Networks (DSN) 2002.
A CRC is an example of a hash function, which refers to any function that can be used to map data of arbitrary size to data of fixed size, with slight differences in input data producing very big differences in an output data. Values returned by the hash function are called hash values, hash codes, hash sums, or simply hashes. Hash values are commonly used to differentiate between data. For example, in implementing a set in software, one has to avoid including an element more than once. Recent developments in internet payment networks also uses a form of ‘hashing’ for producing checksums, bringing additional attention to the term. Hash functions are primarily used to generate fixed-length output data that act as a shortened reference to the original data. This is useful when the original data is too cumbersome to use in its entirety. Hash functions commonly include checksums, check digits, fingerprints, randomization functions, error-correcting codes, and ciphers.
One practical use is a data structure called a hash table where the data is stored associatively. Searching linearly for a person's name in a list becomes cumbersome as the length of the list increases, but the hashed value can be used to store a reference to the original data and retrieve constant time (barring collisions). Another use is in cryptography, the science of encoding and safeguarding data. It is easy to generate hash values from input data and easy to verify that the data matches the hash, but for certain hash functions hard to ‘fake’ a hash value to hide malicious data. Hash functions are also frequently used to accelerate table lookup or data comparison tasks such as finding items in a database, detecting duplicated or similar records in a large file and finding similar stretches in DNA sequences. A hash function should be deterministic: when it is invoked twice on identical data (e.g. two strings containing exactly the same characters), the function should produce the same value. This is crucial to the correctness of virtually all algorithms based on hashing. In the case of a hash table, the lookup operation should look at the slot where the insertion algorithm actually stored the data that is being sought for, so it needs the same hash value.
Hash functions used to accelerate data searches typically produce smaller hash values, such as a 32 bit integer. On the other hand, cryptographic hash functions produce much larger hash value, in order to ensure the computational complexity of brute-force inversion. For example SHA-1, one of the most widely used cryptographic hash functions, produces a 160-bit value. In both cases, the hash function breaks the input data into chunks of specific size. Hash functions used for data searches use an arithmetic expression which iteratively processes those chunks (such as the characters in a string) to produce the hash value. In cryptographic hash functions, these chunks are processed by a one-way compression function, with the last chunk being padded if necessary. In this case, their size, which is called block size, is much bigger than the size of the hash value. For example, in SHA-1, the hash value is 160 bits and the block size 512 bits.
A hash table (a.k.a. Hash map) is a data structure that associates keys with values, and is commonly used to support a lookup: given a key (e.g., a person's name), find the corresponding value (e.g., that person's telephone number), thus allowing to use a number to locate a desired value in a table. Hash tables are typically used to implement an associative array, a structure that can map keys to values. A hash table uses a hash function to compute an index into an array of buckets or slots, from which the correct value can be found. The hash function may assign each key to a unique bucket, but typically hash table designs assume that hash collisions—different keys that are assigned by the hash function to the same bucket—will occur and must be accommodated in some way. In a well-dimensioned hash table, the average cost (number of instructions) for each lookup is independent of the number of elements stored in the table. Many hash table designs also allow arbitrary insertions and deletions of key-value pairs, at a constant average cost per operation. In many situations, hash tables turn out to be more efficient than search trees or any other table lookup structure, and thus are widely used in many kinds of computer software, particularly for associative arrays, database indexing, caches, and sets.
Filter driver. A filter driver is a Microsoft Windows compatible driver that extends or modifies the function of peripheral devices or supports a specialized device in a personal computer. It is a driver or program or module that is inserted into the existing driver stack to perform some specific function, while not affecting the normal working of the existing driver stack in any major way. Any number of filter drivers can be added to Windows, where upper level filter drivers sit above the primary driver for the device (the function driver), while lower level filter drivers sit below the function driver and above a bus driver. Filter drivers may work on a certain brand of device such as a mouse or keyboard, or they may perform some operation on a class of devices, such as any mouse or any keyboard. A filter driver may be developed using the guide entitled: “Filter Driver Development Guide” Version 1.0a by Microsoft Corporation, dated 2004, which is incorporated in its entirety for all purposes as if fully set forth herein.
Hook. A hook (also known as a hook procedure or hook function) is a mechanism by which an application can intercept events, such as messages, mouse actions, and keystrokes, and generally refers to a function provided by a software application that receives certain data before the normal or intended recipient of the data. The hook function can thus examine or modify certain data before passing on the data. Therefore, a hook function allows a software application to examine data before the data is passed to the intended recipient. A function that intercepts a particular type of event is known as a hook procedure. The hook procedure can act on each event it receives, and then modify or discard the event. The term ‘hooking’ is used herein to include, but not limited to, a range of techniques used to alter or augment the behavior of an operating system, of applications, or of other software components by intercepting function calls, messages, or events passed between software components. A code that handles such intercepted function calls, events or messages is called a “hook”. Hooking is used for many purposes, including debugging and extending functionality. Examples might include intercepting keyboard or mouse event messages before they reach an application, or intercepting operating system calls in order to monitor behavior or modify the function of an application or other component. It is also widely used in benchmarking programs, for example frame rate measuring in 3D games, where the output and input is done through hooking. Hooking is described, for example, in the presentations by High-Tech Bridge SA and titled: “Userland Hooking in Windows” dated August 2011, and “Inline Hooking in Windows” dated September 2011, both by Brian Mariani, and both incorporated in their entirety for all purposes as if fully set forth herein.
Physical modification. An hooking may be achieved by physically modifying an executable or library before an application is running through techniques of reverse engineering. This is typically used to intercept function calls to either monitor or replace them entirely. For example, by using a disassembler, the entry point of a function within a module can be found. It can then be altered to instead dynamically load some other library module and then have it execute desired methods within that loaded library. If applicable, another related approach by which hooking can be achieved is by altering an import table of an executable. This table can be modified to load any additional library modules as well as changing what external code is invoked when a function is called by an application. An alternate method for achieving the function of hooking is by intercepting function calls through a wrapper library. When creating a wrapper, you make your own version of a library that an application loads, with all the same functionality of the original library that it will replace, so all the functions that are accessible are essentially the same between the original and the replacement. This wrapper library can be designed to call any of the functionality from the original library, or replace it with an entirely new set of logic.
Runtime modification. Operating systems and software may provide the means to easily insert event hooks at runtime, as long as the process inserting the hook is granted enough permission to do so. Microsoft Windows allows to insert hooks that can be used to process or modify system events and application events for dialogs, scrollbars, and menus, as well as other items. It also allows a hook to insert, remove, process, or modify keyboard and mouse events. Linux provides another example where hooks can be used in a similar manner to process network events within the kernel through NetFilter. When such functionality is not provided, a special form of hooking employs intercepting library function calls that are made by a process. Function hooking is implemented by changing the very first few code instructions of the target function to jump to an injected code. Alternatively on systems using the shared library concept, the interrupt vector table or the import descriptor table can be modified in memory.
A hook chain is a list of pointers to special, application-defined callback functions called hook procedures. When a message occurs that is associated with a particular type of hook, the operating system passes the message to each hook procedure referenced in the hook chain, one after the other. The action of a hook procedure can depend on the type of hook involved. For example, the hook procedures for some types of hooks can only monitor messages, others can modify the messages or stop their progress through the chain, restricting them from reaching the next hook procedure or a destination window.
Plug-in. A plug-in (or ‘plugin’, ‘extension’, or ‘add-on’/‘addon’) is a software component that adds a specific feature to an existing software application, for example for enabling customization. The common examples are the plug-ins used in web browsers to add new features such as search-engines, virus scanners, or the ability to utilize a new file type such as a new video format. An ‘Add-on’ (or ‘addon’) is the general term for what enhances an application, and comprises snap-in, plug-in, theme, and skin. An extension add-on tailors the core features of an application by adding an optional module, whereas a plug-in add-on would tailor the outer layers of an application to personalize functionality. A theme or a skin add-on is a preset package containing additional or changed graphical appearance details, achieved by the use of a Graphical User Interface (GUI) that can be applied to a specific software and websites to suit the purpose, topic, or tastes of different users to customize the look and feel of a piece of computer software or an operating system front-end GUI (and window managers).
Typically, the host application provides services which the plug-in can use, including a way for plug-ins to register themselves with the host application and a protocol for the exchange of data with plug-ins. Plug-ins depend on the services provided by the host application and do not usually work by themselves. Conversely, the host application operates independently of the plug-ins, making it possible for end-users to add and update plug-ins dynamically without needing to make changes to the host application. The term ‘plug-in’ is used herein to include, but not limited to, a software extension, which is software that serves to extend the capabilities of, or data available to an existing software application; it becomes included in the program. Therefore, after integration, extensions can be seen as part of the browser itself, tailored from a set of optional modules.
IPC. An Inter-Process Communication (IPC) (also be referred to as inter-thread communication and inter-application communication) is a set of methods for the exchange of data between multiple threads, in one or more processes. IPC methods may use message passing, synchronization, shared memory, and Remote Procedure Calls (RPC). IPC provides an environment that allows process cooperation, and may be used for providing Information sharing, computational speedup, modularity, convenience, and privilege separation. In the Windows operating system environment, the IPC provides mechanisms for facilitating communications and data sharing between processes or applications.
Common IPC methods include file sharing, where a record (or any other information) stored on disk (or any other memory) can be accessed by name by any process; a signal which is an asynchronous notification sent to a process or to a specific thread within the same process in order to notify it of an event that occurred; a socket which is a data stream sent over a network interface, either to a different process on the same computer or to another computer, such as Internet sockets; a pipe (or pipeline) which is a two-way data stream interfaced through standard input and output and is read character by character, commonly used in Unix-like computer operating systems; message queues which are anonymous data stream similar to the pipe that stores and retrieves information in packets, providing an asynchronous communications protocol; a semaphore which is a variable or abstract data type that is used for controlling access to a common resource; a shared memory which is a memory that may be simultaneously accessed by multiple programs with an intent to provide communication among them or avoid redundant copies, such as where one process creates an area in RAM which other processes can access; and memory mapped file, where a file that is physically present on-disk, but can also be a device, shared memory object, or other resource that the operating system can reference through a file descriptor. Few IPC mechanisms are described in the Marko Vuskovic publication ‘Operating Systems’ in Chapter 9 entitled: “INTERPROCESS COMMUNICATION”, which is incorporated in its entirety for all purposes as if fully set forth herein.
The Windows operating system supports IPC mechanisms such as a clipboard, where the clipboard acts as a central depository for data sharing among applications, so when a user performs a cut or copy operation in an application, the application puts the selected data on the clipboard in one or more standard or application-defined formats, and any other application can then retrieve the data from the clipboard, choosing from the available formats that it understands; using Component Object Model (COM), where applications that use Object Linking and Embedding (OLE) manage compound documents can be used to call on other applications for data editing; Using Data Copy enabling an application to send information to another application using the WM_COPYDATA message; DDE protocol that enables applications to exchange data in a variety of formats; and mailslots providing one-way communication where processes write messages to their mailslot.
Browser extension. A browser extension is a computer program that extends the functionality of a web browser in some way. Extensions can be created through use of web technologies such as HTML, JavaScript, and CSS. Browser extensions can also improve the user interface of the web browser without directly affecting viewable content of a web page, which can be achieved through a variety of add ons such as toolbars and plug-ins. Microsoft Internet Explorer started supporting extensions from version 5 released in 1999. Mozilla Firefox has supported extensions since its launch in 2004. The Opera desktop web browser supported extensions from version 10 released in 2009. Google Chrome started supporting extensions from version 4 released in 2010. The Apple Safari web browser started supporting native extensions from version 5 released in 2010. The syntax for extensions may differ from browser to browser, or at least enough different that an extension working on a browser does not work on another one.
Plug-ins add specific abilities into browsers using Application Programming Interfaces (APIs) allowing third parties to create plug-ins that interact with the browser. The original API was NPAPI, but subsequently Google introduced the PPAPI interface in Chrome. In addition, plug-ins allow browser extensions to perform tasks such as blocking ads, creating a secure online connection, and adding applications within a browser. Well-known browser plug-ins include the Adobe Flash Player, the QuickTime Player, and the Java plug-in, which can launch a user-activated Java applet on a web page to its execution a local Java virtual machine.
Sockets. A socket (a.k.a. ‘network socket’) is an endpoint of an IPC flow across a computer network. In the case the communications is based on IP (Internet Protocol), the network sockets are referred to as Internet sockets. A socket API is an application programming interface (API), usually provided by the operating system, that allows application programs to control and use network sockets. Internet socket APIs are usually based on the Berkeley sockets standard. A socket address is the combination of an IP address and a port number, similar to one end of a telephone connection in the combination of a phone number and a particular extension. Based on this address, internet sockets deliver incoming data packets to the appropriate application process or thread. Sockets are further described in a Universoty of Toronto, Department of Computer Science presentation entitled: “Tutorial on Socket Programming” by Amin Tootoonchian, downloaded on August, 2014, and in the SAS Institute Inc. SHARE Session 5958 tutorial ‘C Socket Programming Tutorial’ entitled: “Writing Client/Server Programs in C Using Sockets (A Tutorial) Part I”, by Greg Granger, dated February of 1998, which are both incorporated in their entirety for all purposes as if fully set forth herein.
An Internet socket is characterized by a unique combination of a Local socket address (Local IP address and port number), remote socket address (used for established TCP sockets), and the used Protocol, typically a transport protocol (e.g., TCP, UDP, raw IP, or others). Within the operating system and the application that created a socket, a socket is referred to by a unique integer value called a socket descriptor. The operating system forwards the payload of incoming IP packets to the corresponding application by extracting the socket address information from the IP and transport protocol headers and stripping the headers from the application data.
Several Internet socket types are available, such as Datagram sockets, also known as connectionless sockets, which use User Datagram Protocol (UDP), Stream sockets, also known as connection-oriented sockets, which use Transmission Control Protocol (TCP) or Stream Control Transmission Protocol (SCTP), and Raw sockets (or Raw IP sockets), typically available in routers and other network equipment. Here the transport layer is bypassed, and the packet headers are made accessible to the application. Other socket types are implemented over other transport protocols, such as Systems Network Architecture (SNA). Communicating local and remote sockets are called socket pairs. Each socket pair is described by a unique 4-tuple consisting of source and destination IP addresses and port numbers, i.e. of local and remote socket addresses. In the TCP case, each unique socket pair 4-tuple is assigned a socket number, while in the UDP case, each unique local socket address is assigned a socket number.
The socket is primarily a concept used in the Transport Layer of the Internet model. Networking equipment such as routers and switches do not require implementations of the Transport Layer, as they operate on the Link Layer level (switches) or at the Internet Layer (routers). However, stateful network firewalls, network address translators, and proxy servers keep track of active socket pairs. Also in fair queuing, layer 3 switching and quality of service (QoS) support in routers, packet flows may be identified by extracting information about the socket pairs. Raw sockets are typically available in network equipment and are used for routing protocols such as IGRP and OSPF, and in Internet Control Message Protocol (ICMP).
The amount of data transferred in a given period in commonly referred to as ‘bandwidth’ (BW) or ‘bit-rate’, which is the number of bits that are conveyed or processed per unit of time. The bit rate is quantified using the bits per second unit (symbol bit/s or b/s), often in conjunction with an SI prefix such as kilo- (1 kbit/s=1000 bit/s), mega- (1 Mbit/s=1000 kbit/s), giga- (1 Gbit/s=1000 Mbit/s) or tera- (1 Tbit/s=1000 Gbit/s). The non-standard abbreviation bps is often used to replace the standard symbol bit/s, so that, for example, “1 Mbps” (or 1 Mb/s) is used to mean one million bits per second. One byte per second (1 B/s) corresponds to 8 bit/s.
Latency is typically defined as a time interval between the stimulation and the response, or, from a more general point of view, as a time delay between the cause and the effect of some physical change in the system being observed. Network-related latency, such as in a packet-switched network, is measured either one-way (the time from the source sending a packet to the destination receiving it), or Round-Trip delay Time (RTT), referring to the one-way latency from source to destination plus the one-way latency from the destination back to the source, plus any delays at the destination, such as processing or other delays. Round-trip latency can be measured from a single point. Latency limits total bandwidth in reliable two-way communication systems as described by the bandwidth-delay product, which refers to the product of a data link's capacity (in bits per second) and its end-to-end delay (in seconds). The result, an amount of data measured in bits (or bytes), is equivalent to the maximum amount of data on the network circuit at any given time, i.e., data that has been transmitted but not yet acknowledged. Sometimes it is calculated as the data link's capacity multiplied by its round trip time. A network with a large bandwidth-delay product is commonly known as a Long Fat Network (LFN). As defined in IETF RFC 1072, a network is considered an LFN if its bandwidth-delay product is significantly larger than 105 bits (12500 bytes).
The Round-trip Delay Time (RTD) or Round-Trip Time (RTT) is the length of time it takes for a signal to be sent and to be received and processed at the destination node, plus the length of time it takes for an acknowledgment of that signal to be received. This time delay therefore includes the propagation times between the two points of a signal. The signal is generally a data packet, and the RTT is also known as the ping time, and an internet user can determine the RTT by using the ping command. Network links with both a high bandwidth and a high RTT can have a very large amount of data (the bandwidth-delay product) “in flight” at any given time. Such “long fat pipes” require a special protocol design. One example is the TCP window scale option. The RTT was originally estimated in TCP by: RTT=(α·Old_RTT)+((1−α)·New_Round_Trip_Sample), where α is a constant weighting factor (0≤α<1). Choosing a value α close to 1 makes the weighted average immune to changes that last a short time (e.g., a single segment that encounters long delay). Choosing a value for α close to 0 makes the weighted average response to changes in delay very quickly. Once a new RTT is calculated, it is entered into the above equation to obtain an average RTT for that connection, and the procedure continues for every new calculation. The RTT may be measured as described in IETF 1323, and may be estimated by using a method described in IETF RFC 6323, which are both incorporated in their entirety for all purposes as if fully set forth herein.
An estimation of RTT for messages using TCP may use Karn's Algorithm, described by Karn, Phil and Craig Partridge in ACM SIGCOMM '87—Computer Communication Review publication, entitled: “Improving Round-Trip Time Estimates in Reliable Transport Protocols”, which is incorporated in its entirety for all purposes as if fully set forth herein. The round trip time is estimated as the difference between the time that a segment was sent and the time that its acknowledgment was returned to the sender, but when packets are re-transmitted there is an ambiguity: the acknowledgment may be a response to the first transmission of the segment or to a subsequent re-transmission. Karn's Algorithm ignores re-transmitted segments when updating the round trip time estimate. Round trip time estimation is based only on unambiguous acknowledgments, which are acknowledgments for segments that were sent only once.
Many software platforms provide a service called ‘ping’ that can be used to measure round-trip latency. Ping performs no packet processing; it merely sends a response back when it receives a packet (i.e., performs a no-op), thus it is a first rough way of measuring latency. Ping operates by sending Internet Control Message Protocol (ICMP) echo requesting packets to the target host, and waiting for an ICMP response. During this process it measures the time from transmission to reception (round-trip time) and records any packet loss. The results of the test are printed in a form of a statistical summary of the response packets received, including the minimum, maximum, and the mean round-trip times, and sometimes the standard deviation of the mean.
The Transmission Control Protocol/Internet Protocol (TCP/IP) suite normally used on the Internet has included an Internet Message Control Protocol (ICMP) that is commonly used in echo testing or ping and trace route applications. In general, the Internet standard ‘ping’ or ‘ICMP echo’ has a request/response format, wherein one device sends an ICMP echo request and another device responds to a received ICMP echo request with a transmitted ICMP echo response. Normally, IP devices are expected to implement the ICMP as part of the support for IP, to be able to use ICMP for testing. Internet RFC 792, entitled “Internet Control Message Protocol: DARPA Internet Program Protocol Specification”, which is incorporated in its entirety for all purposes as if fully set forth herein, at least partially describes the behavior of ICMP. The ICMP echo message has a type field, a code field, a checksum field, an identifier field, a sequence number field, and a data field. According to RFC 79: “The data received in the echo message must be returned in the echo reply message”. Thus, an RFC compliant ping responders or an ICMP echo reply message responders are supposed to copy the received data field in an echo request message directly into the data field of the transmitted echo response message.
A newer version of ICMP known as ICMP version 6 or ICMPv6 as described at least partially in RFCs 1885 and 2463, which are both entitled “Internet Control Message Protocol (ICMPv6) for the Internet Protocol Version 6 (IPv6) Specification”, which are both incorporated in their entirety for all purposes as if fully set forth herein. According to RFC 2463, “Every [IPv6] node MUST implement an ICMPv6 Echo responder function that receives Echo Requests and sends corresponding Echo Replies. An IPv6 node SHOULD also implement an application-layer interface for sending Echo Requests and receiving Echo Replies, for diagnostic purposes.”. Thus, responding to ICMP echo requests normally is a necessary function in supporting IPv4 and/or IPv6 standards. The ICMPv6 RFCs 1885 and 2464 goes on to specify that the data field of an ICMP echo response contains the “data from the invoking Echo Request message.” Therefore, both ICMP and ICMP v6 associated with IPv4 and IPv6, respectively, specify that the data field in an ICMP echo reply message is to essentially contain a copy of the data received in the corresponding ICMP echo request message.
Moreover, the ICMP echo protocol is basically a two-way echo in which one initiating device and/or process starts the communication by transmitting an echo request message, which may be then received by an echo responder process. The echo responder process, generally located on another device, receives the echo request message and responds with an echo reply back to the initiating process. Once the initiating device and/or process receives the response or times out waiting on the response, the two-way echo exchange of messages is complete. Although the echo request and echo response normally are performed between processes on two different devices, one skilled in the art will be aware that a device can ping its own IP address implying that the echo request and echo responder reply processes are on the same device. In addition, the loopback address of network 127.0.0.0 in IPv4 can be used to allow a device to the loopback outbound echo request messages back into the device's own incoming echo request responder processes. IPv6 has a loopback functionality as well.
This copying of data exactly in the ICMP echo response is somewhat wasteful because the responder generally does not convey that much (if any) information back to the ICMP echo request initiating device. Arguably the initiating device could compute bit error rate (BER) statistics on the transmitted versus the received data field in ICMP echo packets. However, such physical layer issues as BER statistics normally are not as relevant for network layer IP datagranis that already include various error control code mechanisms. Arguably the device running the responding process can communicate information to the device running the initiating process by having the device running the original responding process initiate its own echo request and wait for an echo response from the original initiating device. Such a solution results in four packets, with a first echo request from a local device responded to by a first echo response from a remote device, and with a second echo request from the remote device responded to by a second echo response from the local device.
An identifier and/or sequence number in ping packets generally has allowed the ping to be used by a device to determine the round-trip delay from the time an ICMP echo request packet is sent to the time corresponding to when an associated received ICMP echo request is received back at an initiating device. Furthermore, ping packets generally convey little or no information about the type of the device that initiated the ping. Moreover, although IPv4 has Type of Service (ToS) fields in the IP datagram, these fields have become more important as the services used over the Internet and networks using Internet technology have grown from basic computer data communication to also include real-time applications such as voice and/or video. Various Type of Service (ToS) in IPv4 and IPv6 have been used in implementing various (Quality of Service) QoS characteristics that are defined for different classes of service and/or Service Level Agreements (SLAs).
Timestamp. A timestamp is a sequence of characters or encoded information identifying when a certain event occurred, usually giving date and time of day, sometimes accurate to a small fraction of a second, and also refers to digital date and time information attached to the digital data. For example, computer files contain timestamps that tell when the file was last modified, and digital cameras add timestamps to the pictures they take, recording the date and time the picture was taken. A timestamp is typically the time at which an event is recorded by a computer, not the time of the event itself. In many cases, the difference may be inconsequential: the time at which an event is recorded by a timestamp (e.g., entered into a log file) should be close to the time of the event. Timestamps are typically used for logging events or in a Sequence of Events (SOE), in which case each event in the log or SOE is marked with a timestamp. In a file system such as a database, timestamp commonly mean the stored date/time of creation or modification of a file or a record. The ISO 8601 standard standardizes the representation of dates and times which are often used to construct timestamp values, and IETF RFC 3339 defines a date and time format for use in Internet protocols using the ISO 8601 standard representation.
Caching. A system and method for increasing cache size by performing the steps of: categorizing storage blocks within a storage device as within a first category of storage blocks if the storage blocks that are available to the system for storing data when needed; categorizing storage blocks within the storage device as within a second category of storage blocks if the storage blocks contain application data therein; and categorizing storage blocks within the storage device as within a third category of storage blocks if the storage blocks are storing cached data and are available for storing application data if no first category of storage blocks are available to the system, is described in U.S. Pat. No. 8,135,912 to Shribman et al. entitled: “System and Method of Increasing Cache Size”, which is incorporated in its entirety for all purposes as if fully set forth herein. A system for resolving Domain Name System (DNS) queries that contains a communication device for resolving DNS queries, wherein the communication device further contains a memory and a processor that is configured by the memory, a cache storage for use by the communication device, and a network of authoritative domain name servers, where in a process of the communication device looking up a DNS request within the cache storage, if the communication device views an expired DNS entry within the cache storage, the communication device continues the process of looking up the DNS request in the cache storage while, in parallel, sending out a concurrent DNS request to an authoritative domain name server that the expired DNS entry belongs to, is described in U.S. Pat. No. 8,671,221 to the same inventors as this application, entitled: “Method and System for Increasing Speed of Domain Name System Resolution within a Computing Device”, which is incorporated in its entirety for all purposes as if fully set forth herein.
Systems and methods of storing previously transmitted data and using it to reduce bandwidth usage and accelerate future communications, and using algorithms to identify long compression history matches. A network device that may improve compression efficiency and speed is described in U.S. Pat. No. 7,865,585 to Samuels et al., entitled: “Systems and Methods for Providing Dynamic Ad Hok Proxy-Cache Hierarchies”, which is incorporated in its entirety for all purposes as if fully set forth herein. Further, a method and system for accelerating the receipt of data in a client-to-client network described in U.S. Pat. No. 7,203,741 to Marco et al., entitled: “Method and System for Accelerating Receipt of Data in a Client-to-Client Network”, which is incorporated in its entirety for all purposes as if fully set forth herein.
Hearbeat. A heartbeat is a periodic signal generated by hardware or software to indicate normal operation or to synchronize other parts of a system. Usually a heartbeat is sent between machines at a regular interval of an order of seconds. If a heartbeat is not received for a time—usually a few heartbeat intervals—the machine that should have sent the heartbeat is assumed to have failed. As used herein, a heartbeat is a periodic message, such as a ‘ping’, generated by devices connected to the Internet to indicate being ‘online’ (connected to the Internet) and normal operation, and if a heartbeat is not received for a time, the device is assumed to be ‘offline’ (not connected to the Internet). A heartbeat protocol is generally used to negotiate and monitor the availability of a resource, such as a floating IP address. Typically, when a heartbeat starts on a machine, it will perform an election process with other machines on the network to determine which machine, if any, owns the resource. The IETF RFC 6520 describes Heartbeat operation for the Transport Layer Security (TLS), and is incorporated in its entirety for all purposes as if fully set forth herein.
Users in the Internet may desire anonymity in order not to be identified as a publisher (sender), or reader (receiver), of information. Common reasons include censorship at the local, organizational, or national level, personal privacy preferences such as preventing tracking or data mining activities, the material or its distribution is considered illegal or incriminating by possible eavesdroppers, the material may be legal but socially deplored, embarrassing, or problematic in the individual's social world, and fear of retribution (against whistleblowers, unofficial leaks, and activists who do not believe in restrictions on information nor knowledge). Full anonymity on the Internet, however, is not guaranteed since IP addresses can be tracked, allowing to identify the computer from which a certain post was made, albeit not the actual user. Anonymizing services, such as I2P—‘The Anonymous Network’ or Tor, address the issue of IP tracking, as their distributed technology approach may grant a higher degree of security than centralized anonymizing services where a central point exists that could disclose one's identity. An anonymous web browsing refers to browsing the World Wide Web while hiding the user's IP address and any other personally identifiable information from the websites that one is visiting. There are many ways of accomplishing anonymous web browsing. Anonymous web browsing is generally useful to internet users who want to ensure that their sessions cannot be monitored. For instance, it is used to circumvent traffic monitoring by organizations that want to find out or control which web sites employees visit. Further, since some web-sites response differently when approached from mobile devices, anonymity may allow for accessing such a web-site from a non-mobile device, posing as a mobile device.
WiFi. A device herein (such as device 11) may consist of, be part of, or include, a Personal Computer (PC), a desktop computer, a mobile computer, a laptop computer, a notebook computer, a tablet computer, a server computer, a handheld computer, a handheld device, a Personal Digital Assistant (PDA) device, or a cellular handset. Alternatively or in addition, a device may consist of, be part of, or include, a handheld PDA device, an on-board device, an off-board device, a hybrid device, a vehicular device, a non-vehicular device, a mobile device, or a portable device. A network herein (such as LAN 14), may consist of, be part of, or include, a wired or wireless network, a Local Area Network (LAN), a Wireless LAN (WLAN), a Metropolitan Area Network (MAN), a Wireless MAN (WMAN), a Wide Area Network (WAN), a Wireless WAN (WWAN), a Personal Area Network (PAN), or a Wireless PAN (WPAN). Alternatively or in addition, a network herein may be operating substantially in accordance with existing IEEE 802.11, 802.11a, 802.11b, 802.11g, 802.11k, 802.11n, 802.11r, 802.16, 802.16d, 802.16e, 802.20, 802.21 standards and/or future versions and/or derivatives of the above standards. Further, a network element (or a device) herein may consist of, be part of, or include, a cellular radio-telephone communication system, a cellular telephone, a wireless telephone, a Personal Communication Systems (PCS) device, a PDA device which incorporates a wireless communication device, or a mobile/portable Global Positioning System (GPS) device. The communication interface 29 may consist of, be part of, or include, a transceiver or modem for communication with the network, such as LAN 14. In the case of wired networks, the communication interface 29 connects to the network via a port 28 that may include a connector, and in the case of wireless network, the communication interface 29 connects to the network via a port 28 that may include an antenna.
The LAN 14 may be a Wireless LAN (WLAN) such as according to, or base on, IEEE 802.11-2012, and the WLAN port may be a WLAN antenna and the WLAN transceiver may be a WLAN modem. The WLAN may be according to, or base on, IEEE 802.11a, IEEE 802.11b, IEEE 802.11g, IEEE 802.11n, or IEEE 802.11ac. Commonly referred to as Wireless Local Area Network (WLAN), such communication makes use of the Industrial, Scientific and Medical (ISM) frequency spectrum. In the US, three of the bands within the ISM spectrum are the A-Band, 902-928 MHz; the B-Band, 2.4-2.484 GHz (a.k.a. 2.4 GHz); and the C-Band, 5.725-5.875 GHz (a.k.a. 5 GHz). Overlapping and/or similar bands are used in different regions such as Europe and Japan. In order to allow interoperability between equipment manufactured by different vendors, few WLAN standards have evolved, as part of the IEEE 802.11 standard group, branded as WiFi (www.wi-fi.org). The IEEE 802.11b standard describes a communication using the 2.4 GHz frequency band and supporting a communication rate of 11 Mb/s, IEEE 802.11a uses the 5 GHz frequency band to carry 54 MB/s, and IEEE 802.11g uses the 2.4 GHz band to support 54 Mb/s. The WiFi technology is further described in a publication entitled: “WiFi Technology” by Telecom Regulatory Authority, published on July 2003, which is incorporated in its entirety for all purposes as if fully set forth herein. The IEEE 802 defines an ad-hoc connection between two or more devices without using a wireless access point: the devices communicate directly when in range. An ad hoc network offers peer-to-peer layout and is commonly used in situations such as a quick data exchange or a multiplayer LAN game, because the setup is easy and an access point is not required.
In order to support multiple devices and using a permanent solution, a Wireless Access Point (WAP) is typically used. A Wireless Access Point (WAP, or Access Point—AP) is a device that allows wireless devices to connect to a wired network using Wi-Fi, or related standards. The WAP usually connects to a router (via a wired network) as a standalone device, but it can also be an integral component of the router itself. Using Wireless Access Point (AP) allows users to add devices that access the network with little or no cables. A WAP normally connects directly to a wired Ethernet connection and the AP then provides wireless connections using radio frequency links for other devices to utilize that wired connection. Most APs support the connection of multiple wireless devices to one wired connection. An example of using WAPs is shown in a system 20a shown in FIG. 2b, where a device 11a (corresponding to the device 11 above) may communicate, and for example, any access the Internet, via any one of a WAPs 26a, 26b, or 26c. Wireless access typically involves special security considerations, since any device within a range of the WAP can attach to the network. The most common solution is wireless traffic encryption. Modern access points come with built-in encryption such as Wired Equivalent Privacy (WEP) and Wi-Fi Protected Access (WPA), typically used with a password or a passphrase. A WAP may not be password protected, allowing free access (for example to the Internet via the WAP) to any device communicating with it, such as WAP 26a shown in system 20a. However, most WAPs, such as WAPs 26b and 26c shown in system 20a (denoted with the lock symbol), are password protected, allowing access only to specific users which can use the password.
Authentication in general, and a WAP authentication in particular, is used as the basis for authorization, which is the determination whether a privilege may be granted to a particular user or process, privacy, which keeps information from becoming known to non-participants, and non-repudiation, which is the inability to deny having done something that was authorized to be done based on the authentication. An authentication in general, and a WAP authentication in particular, may use an authentication server, that provides a network service that applications may use to authenticate the credentials, usually account names and passwords, of their users. When a client submits a valid set of credentials, it receives a cryptographic ticket that it can subsequently use to access various services. Authentication algorithms include passwords, Kerberos, and public key encryption.
Compression. Data compression, also known as source coding and bit-rate reduction, involves encoding information using fewer bits than the original representation. Compression can be either lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy, so that no information is lost in lossless compression. Lossy compression reduces bits by identifying unnecessary information and removing it. The process of reducing the size of a data file is commonly referred to as a data compression. A compression is used to reduce resource usage, such as data storage space or transmission capacity. Data compression is further described in a Carnegie Mellon University chapter entitled: “Introduction to Data Compression” by Guy E. Blelloch, dated Jan. 31, 2013, which is incorporated in its entirety for all purposes as if fully set forth herein.
In a scheme involving lossy data compression, some loss of information is acceptable. For example, dropping of a nonessential detail from a data can save storage space. Lossy data compression schemes may be informed by research on how people perceive the data involved. For example, the human eye is more sensitive to subtle variations in luminance than it is to variations in color. JPEG image compression works in part by rounding off nonessential bits of information. There is a corresponding trade-off between preserving information and reducing size. A number of popular compression formats exploit these perceptual differences, including those used in music files, images, and video.
Lossy image compression is commonly used in digital cameras, to increase storage capacities with minimal degradation of picture quality. Similarly, DVDs use the lossy MPEG-2 Video codec for video compression. In lossy audio compression, methods of psychoacoustics are used to remove non-audible (or less audible) components of the audio signal. Compression of human speech is often performed with even more specialized techniques; speech coding, or voice coding, is sometimes distinguished as a separate discipline from audio compression. Different audio and speech compression standards are listed under audio codecs. Voice compression is used in Internet telephony, for example, and audio compression is used for CD ripping and is decoded by audio player.
Lossless data compression algorithms usually exploit statistical redundancy to represent data more concisely without losing information, so that the process is reversible. Lossless compression is possible because most real-world data has statistical redundancy. The Lempel-Ziv (LZ) compression methods are among the most popular algorithms for lossless storage. DEFLATE is a variation on LZ optimized for decompression speed and compression ratio, and is used in PKZIP, Gzip and PNG. The LZW (Lempel-Ziv-Welch) method is commonly used in GIF images, and is described in IETF RFC 1951. The LZ methods use a table-based compression model where table entries are substituted for repeated strings of data. For most LZ methods, this table is generated dynamically from earlier data in the input. The table itself is often Huffman encoded (e.g., SHRI, LZX). Typical modern lossless compressors use probabilistic models, such as prediction by partial matching.
Lempel-Ziv-Welch (LZW) is an example of lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. The algorithm is simple to implement, and has the potential for very high throughput in hardware implementations. It was the algorithm of the widely used Unix file compression utility compress, and is used in the GIF image format. The LZW and similar algorithms are described in U.S. Pat. No. 4,464,650 to Eastman et al. entitled: “Apparatus and Method for Compressing Data Signals and Restoring the Compressed Data Signals”, in U.S. Pat. No. 4,814,746 to Miller et al. entitled: “Data Compression Method”, and in U.S. Pat. No. 4,558,302 to Welch entitled: “High Speed Data Compression and Decompression Apparatus and Method”, which are all incorporated in their entirety for all purposes as if fully set forth herein.
A class of lossless data compression algorithms is based on using dictionaries, and operates by searching for matches between the text to be compressed and a set of strings contained in a data structure (called the ‘dictionary’) maintained by the encoder. When the encoder finds such a match, it substitutes a reference to the string's position in the data structure.
Some dictionary coders use a ‘static dictionary’, one whose full set of strings is determined before coding begins and does not change during the coding process. This approach is most often used when the message or set of messages to be encoded is fixed and large. A dictionary is often built from redundancy extracted from a data environment (various input streams) which dictionary is then used statically to compress a further input stream. For example, a dictionary may be built from old English texts then is used to compress a book. More common are methods where the dictionary starts in some predetermined state, but the contents change during the encoding process, based on the data that has already been encoded.
Both the LZ77 and LZ78 algorithms work on this principle, where in LZ77, a circular buffer called the “sliding window” holds the last N bytes of data processed, which serves as the dictionary, effectively storing every substring that has appeared in the past N bytes as dictionary entries. Instead of a single index identifying a dictionary entry, two values are needed: the length, indicating the length of the matched text, and the offset (also called the distance), indicating that the match is found in the sliding window starting offset bytes before the current text. LZ78 uses a more explicit dictionary structure; at the beginning of the encoding process, the dictionary only needs to contain entries for the symbols of the alphabet used in the text to be compressed, but the indexes are numbered in order to leave spaces for many more entries. At each step of the encoding process, the longest entry in the dictionary that matches the text is found, and its index is written to the output; the combination of that entry and the character that followed it in the text is then added to the dictionary as a new entry. An example of a dictionary-based compression is described in an University of Michigan paper entitled: “Dictionary-Based Compression for Long Time-Series Similarity” by Willis Lang, Michael Morse, and Jignesh M. Patel, downloaded from http://pages.cs.wisc.edu/ on August 2014, which is incorporated in its entirety for all purposes as if fully set forth herein.
A one-way dictionary-based compression system is shown as a system 470 in FIG. 4. An encoding device 471 is shown to transmit data, such as DATA_1 to a decoding device 472 via a network 480, which may be the Internet 113. The encoding device 471 comprises an encoder 474 (also referred to as a coder, data coder, or data compressor), serving to compress DATA_1 received at an input port 475a into a DATA_2 (which is a lossless compression of DATA_1, preferably having a lower number of bits or lower data-rate that DATA_1) at an output port 475b, using the content in a shared dictionary 473a. The output DATA_2 is transmitted via the network 480, and is received at an input port 476a of a decoder 477 (also referred to as a data decoder or data decompressor) in the decoding device 472. Using a shared dictionary 473b in the decoding device 472, which preferably includes the same content as in the shared dictionary 473a of the encoding device 471, the decoder 477 reconstructs the original data DATA_1 at an output port 476b. 
A two-way dictionary-based compression system is shown as a system 470a in FIG. 4a. An encoding/decoding device 471c includes the functionalities of an encoding device 471a for transmitting, and of a decoding device 472a for receiving data. Similarly, an encoding/decoding device 472c includes the functionalities of the encoding device 471a for transmitting, and of the decoding device 472a for receiving data. In addition to the functionality of the decoding device 472a, the encoding/decoding device 472c is shown to also transmit data, such as DATA_3 to the encoding/decoding device 471c via the network 480, which may be the Internet 113. The encoding/decoding device 472c comprises an encoder 474b (also referred to as a coder, data coder, or data compressor), serving to compress DATA_3 received at an input port 475c into a DATA_4 (which is a lossless compression of DATA_3, preferably having a lower number of bits or lower data-rate that DATA_3) at an output port 475d, using the content in a shared dictionary 473d. The output DATA_4 is transmitted via the network 480, and is received at an input port 476d of a decoder 477b (also referred to as a data decoder or data decompressor) in the encoding/decoding device 471c. Using the shared dictionary 473c in the encoding/decoding device 471c, which preferably includes the same content as in the shared dictionary 473d of the encoding/decoding device 472c, the decoder 477b reconstructs the original data DATA_3 at an output port 476c. 
Image/video. Any content herein may consist of, be part of, or include, an image or a video content. A video content may be in a digital video format that may be based on one out of: TIFF (Tagged Image File Format), RAW format, AVI, DV, MOV, WMV, MP4, DCF (Design Rule for Camera Format), ITU-T H.261, ITU-T H.263, ITU-T H.264, ITU-T CCIR 601, ASF, Exif (Exchangeable Image File Format), and DPOF (Digital Print Order Format) standards. A intraframe or interframe compression may be used, and the compression may a lossy or a non-lossy (lossless) compression, that may be based on a standard compression algorithm, which may be one or more out of JPEG (Joint Photographic Experts Group) and MPEG (Moving Picture Experts Group), ITU-T H.261, ITU-T H.263, ITU-T H.264 and ITU-T CCIR 601.
Web Analytics. Web analytics typically refers to the measurement, collection, analysis, and reporting of web data for purposes of understanding and optimizing web usage. Web analytics is commonly used for measuring web traffic, and may be used as a tool for business and market research, as well as to assess and improve the effectiveness of a web site. Web analytics applications can also help companies measure the results of traditional print or broadcast advertising campaigns. For example, it helps one to estimate how traffic to a website changes after the launch of a new advertising campaign. The web analytics provide information about the number of visitors to a website and the number of page views, and helps gauge traffic and popularity trends, which may be useful for market research. Web analytics related description and methods are described in a whitepaper by E-Nor, Inc. entitled: “A 7-Step Analytics Reporting Framework—Marketing Optimization Whitepaper” by Feras Alhlou, downloaded on August 2014, and in U.S. Pat. No. 8,234,370 to Hammer et al., entitled: “Determining Web Analytics Information”, in U.A. Patent Application Publication No. 2008/0046562 to Butler entitled: “Visual Web Page Analytics”, and in U.S. Pat. No. 7,941,525 to Yavilevich entitled: “Method and System for Monitoring an Activity of a User”, which are all incorporated in their entirety for all purposes as if fully set forth herein.
There are two categories of web analytics: off-site and on-site web analytics. Off-site web analytics refers to web measurement and analysis, and includes the measurement of a website's potential audience (opportunity), share of voice (visibility), and buzz (comments) that is happening on the Internet. On-site web analytics measure a visitor's behavior once on the website, and includes its drivers and conversions; for example, the degree to which different landing pages are associated with online purchases. On-site web analytics typically measures the performance of the website in a commercial context, and this data is typically compared against key performance indicators for performance, and used to improve a web site or marketing campaign's audience response. Google Analytics is a widely used on-site web analytics service; although new tools are emerging that provide additional layers of information, including heat maps and session replay.
Google Analytics is a service offered by Google that generates detailed statistics about a website's traffic and traffic sources and measures conversions and sales. The product is aimed at marketers as opposed to webmasters and technologists from which the industry of web analytics originally grew. Google Analytics can track visitors from all referrers, including search engines and social networks, direct visits and referring sites, and also tracks display advertising, pay-per-click networks, email marketing and digital collateral such as links within PDF documents. Integrated with AdWords, users can now review online campaigns by tracking landing page quality and conversions (goals). Goals might include sales, lead generation, viewing a specific page, or downloading a particular file.
Google Analytics is implemented with “page tags”. A page tag, in this case called the Google Analytics Tracking Code is a snippet of JavaScript code that the website owner user adds to every page of the web site. The tracking code runs in the client browser when the client browses the page (if JavaScript is enabled in the browser), and collects visitor data and sends it to a Google data collection server, as part of a request for a web beacon. The tracking code loads a larger JavaScript file from the Google webserver and then sets variables with the user's account number. The larger file (currently known as ga.js) is typically 18 KB. The file does not usually have to be loaded, though, because of browser caching. Assuming caching is enabled in the browser, it downloads ga.js only once at the start of the visit. Furthermore, as all websites that implement Google Analytics with the ga.js code use the same master file from Google, a browser that has previously visited any other website running Google Analytics will already have the file cached on their machine. In addition to transmitting information to a Google server, the tracking code sets first party cookies (If cookies are enabled in the browser) on each visitor's computer. These cookies store anonymous information, such as whether the visitor has been to the site before (new or returning visitor), the timestamp of the current visit, and the referrer site or campaign that directed the visitor to the page (e.g., search engine, keywords, banner, or email). Google Analytics is further described in an Koozai Ltd. guide entitled: “The Practical Guide To Google Analytics For Business”, 2nd Edition, published 2013, by Anna Lewis, Graeme Benge, and Gemma Hollooway, which is incorporated in its entirety for all purposes as if fully set forth herein.
DHCP. The Dynamic Host Configuration Protocol (DHCP) is a standardized networking protocol used on Internet Protocol (IP) networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services. With DHCP, network elements request IP addresses and networking parameters automatically from a DHCP server, reducing the need for a network administrator or a user to configure these settings manually.
DHCP is typically used by network elements for requesting Internet Protocol parameters, such as an IP address from a network server, and is based on the client-server model. When a network element connects to a network, its DHCP client software in the operating system sends a broadcast query requesting necessary information. Any DHCP server on the network may service the request. The DHCP server manages a pool of IP addresses and information about client configuration parameters such as default gateway, domain name, the name servers, and time servers. On receiving a request, the server may respond with specific information for each client, as previously configured by an administrator, or with a specific address and any other information valid for the entire network, and the time period for which the allocation (lease) is valid. A host typically queries for this information immediately after booting, and periodically thereafter before the expiration of the information. When an assignment is refreshed by the client computer, it initially requests the same parameter values, and may be assigned a new address from the server, based on the assignment policies set by administrators.
Depending on implementation, the DHCP server may have three methods of allocating IP-addresses: (a) Dynamic allocation, where a network administrator reserves a range of IP addresses for DHCP, and each client computer on the LAN is configured to request an IP address from the DHCP server during network initialization. The request-and-grant process uses a lease concept with a controllable time period, allowing the DHCP server to reclaim (and then reallocate) IP addresses that are not renewed. (b) Automatic allocation, where the DHCP server permanently assigns an IP address to a requesting client from the range defined by the administrator. This is similar to dynamic allocation, but the DHCP server keeps a table of past IP address assignments, so that it can preferentially assign to a client the same IP address that the client previously had. (c) Static allocation, where the DHCP server allocates an IP address based on a preconfigured mapping to each client's MAC address.
DHCP used for Internet Protocol version 4 (IPv4) is described in IETF RFC 2131, entitled “Dynamic Host Configuration Protocol”, and DHCP for IPv6 is described IETF RFC 3315, entitled: “Dynamic Host Configuration Protocol for IPv6 (DHCPv6)”, both incorporated in their entirety for all purposes as if fully set forth herein. While both versions serve the same purpose, the details of the protocol for IPv4 and IPv6 are sufficiently different that they may be considered separate protocols. For IPv6 operation, devices may alternatively use stateless address auto-configuration. IPv4 hosts may also use link-local addressing to achieve operation restricted to the local network link.
The DHCP protocol employs a connectionless service model, using the User Datagram Protocol (UDP). It is implemented with two UDP port numbers for its operations, which are the same as for the BOOTP protocol. The UDP port number 67 is the destination port of a server, and the UDP port number 68 is used by the client. DHCP operations fall into four phases: Server discovery, IP lease offer, IP request, and IP lease acknowledgment. These stages are often abbreviated as DORA for discovery, offer, request, and acknowledgment. The DHCP protocol operation begins with clients broadcasting a request. If the client and server are on different subnets, a DHCP Helper or DHCP Relay Agent may be used. Clients requesting renewal of an existing lease may communicate directly via an UDP unicast, since the client already has an established IP address at that point.
Redundancy. A redundancy may be used in order to improve an accuracy, reliability, or availability. The redundancy may be implemented where two or more components may be used for the same functionality. The components may be similar, substantially or fully the same, identical, different, substantially different, or distinct from each other, or any combination thereof. The redundant components may be concurrently operated, allowing for improved robustness and allowing for overcoming a Single Point Of Failure (SPOF), or alternatively one or more of the components serves as a backup. The redundancy may be a standby redundancy, which may be ‘Cold Standby’ and ‘Hot Standby’. In the case three redundant components are used, Triple Modular Redundancy (TMR) may be used, and Quadruple Modular Redundancy (QMR) may be used in the case of four components. A 1:N Redundancy logic may be used for three or more components. A communication system employing redundancy is described in U.S. Patent Application No. 2013/0201316 to Binder et al., entitled: “System and Method for Server Based Control”, and redundancy for carrying audio over the Internet is described in IETF RFC 2198 entitled: “RTP Payload for Redundant Audio Data”, both are incorporated in their entirety for all purposes as if fully set forth herein.
Parallel Redundancy Protocol (PRP) is a data communication network standardized by the International Electrotechnical Commission (IEC) as IEC 62439-3 Clause 4, which allows systems to overcome any single network failure without affecting the data transmission by using redundancy. Under PRP, each network node has two Ethernet ports attached to two different local area networks of arbitrary, but similar topology, and the two LANs are completely separated and are assumed to be fail-independent. A source node sends simultaneously two copies of a frame, one over each port. The two frames travel through their respective LANs until they reach a destination node, in the fault-free case, with a certain time skew. The destination node accepts the first frame of a pair and discards the second, taking advantage of a sequence number in each frame that is incremented for each frame sent. Therefore, as long as one LAN is operational, the destination always receives one frame. This protocol provides a zero-time recovery and allows checking the redundancy continuously to detect lurking failures. The PRP is described in an ABB Switzerland Ltd. 2012 presentation entitled “Highly Available Automation Networks Standard Redundancy Methods—Rationale behind the IEC 63429 standard suite”, and in a Zurich University tutorial entitled: “Tutorial on Parallel redundancy Protocol (PRP)”, by Prof. Hans Weibel, downloaded July 2014, both are incorporated in their entirety for all purposes as if fully set forth herein.
Gateway. The term ‘gateway’ is used herein to include, but not limited to, a network element (or node) that is equipped for interfacing between networks that uses different protocols. A gateway typically contains components such as protocol translators, impedance matching devices, rate converters, fault isolators, or signal translators, as necessary to provide networking interoperability. A gateway may be a router or a proxy server that routes between networks, and may operate at any network layer. In a network for an enterprise, a computer server acting as a gateway node is often also acting as a proxy server and a firewall server. A gateway is often associated with both a router, which knows where to direct a given packet of data that arrives at the gateway, and a switch, which furnishes the actual path in and out of the gateway for a given packet.
A subnet mask is a mask used to determine what subnet belongs to an IP address. An IP address has two components, the network address and the host address. For example, consider the IP address 150.215.017.009. Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network. A subnetting enables the network administrator to further divide the host part of the address into two or more subnets. In this case, a part of the host address is reserved to identify the particular subnet. On an IP network, clients should automatically send IP packets with a destination outside a given subnet mask to a network gateway. A subnet mask defines the IP range of a private network. For example, if a private network has a base IP address of 192.168.0.0 and has a subnet mask of 255.255.255.0, then any data going to an IP address outside of 192.168.0.X will be sent to that network gateway. While forwarding an IP packet to another network, the gateway might or might not perform Network Address Translation (NAT).
Domain Name System (DNS) is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities, and translates easily memorized domain names to the numerical IP addresses needed for the purpose of locating computer services and devices worldwide. The DNS is described, for example, in the IETF RFC 3467 entitled: “Role of the Domain Name System (DNS)”, in the IETF RFC 6195 entitled: “Domain Name System (DNS) LANA Considerations”, and in the IETF RFC 1591 entitled: “Domain Name System Structure and Delegation”, which are incorporated in their entirety for all purposes as if fully set forth herein.
The ‘404’ or ‘Not Found’ error message is a HTTP standard response code indicating that the client was able to communicate with a given gateway or server, but the server could not find what was requested. The web site hosting server will typically generate a “404 Not Found” web page when a user attempts to follow a broken or dead link; hence, the 404 error is one of the most recognizable errors users can find on the web. When communicating via HTTP, a server is required to respond to a request, such as a web browser request for a web page, with a numeric response code and an optional, mandatory, or disallowed (based upon the status code) message. In the code 404, the first digit indicates a client error, such as a mistyped Uniform Resource Locator (URL). The following two digits indicate the specific error encountered. At the HTTP level, a 404 response code is followed by a human-readable “reason phrase”. The HTTP specification suggests the phrase “Not Found” and many web servers by default issue an HTML page that includes both the 404 code and the “Not Found” phrase.
Referring to FIG. 50 showing a system 500 using a gateway #1 505a as an intermediate device between a LAN 503 (which may be the LAN 14 in FIG. 1) and a WAN 502 (which may be the Internet 113). The gateway #1 505a allows an application 506 in the network element 504 to communicate with another network element such as a server 501 via the networks. The network element 504 typically includes a memory, such as the main memory 25a, the storage device 25c, or the ROM 25b, storing a software 508, which typically includes the application 506, which uses the Operating System (OS) 507, which may be associated with the WDM architecture 430 shown in FIG. 3, or with the Linux architecture 450 shown in FIG. 3a. As part of initializing of a communication session with the network element 501, the OS 507 typically identifies the gateway 505a in the LAN 503, and obtains therefrom the required information such as an IP address, a DNS server IP, a subnet mask, and other information to be used before and during the communication session. The gateway #1 505a may consist of, include, be part of, or integrated with, a network router or a WiFi router.
In consideration of the foregoing, it would be an advancement in the art to provide an improved functionality method and system that is simple, secure, anonymous, cost-effective, load balanced, redundant, reliable, provide lower CPU and/or memory usage, enable pipelining of requests and responses, reduce network congestion, easy to use, reduce latency, faster, has a minimum part count, minimum hardware, and/or uses existing and available components, protocols, programs and applications for providing better quality of service, overload avoidance, better or optimal resources allocation, better communication and additional functionalities, and provides a better user experience.
USPTO Backgrounds
USPTO Backgrounds