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Virtual private network

Virtual private network
VPN connectivity overview A virtual private network connection across the Internet is similar to a wide area network (WAN) link between sites. From a user perspective, the extended network resources are accessed in the same way as resources available within the private network.[2] VPNs allow employees to securely access their company's intranet while traveling outside the office. Similarly, VPNs securely connect geographically disparate offices of an organization, creating one cohesive network. Types[edit] Early data networks allowed VPN-style remote connectivity through dial-up modems or through leased line connections utilizing Frame Relay and Asynchronous Transfer Mode (ATM) virtual circuits, provisioned through a network owned and operated by telecommunication carriers. VPNs can be either remote-access (connecting an individual computer to a network) or site-to-site (connecting two networks together). VPN systems may be classified by: Security mechanisms[edit] Authentication[edit]

Information Warfare Monitor The Information Warfare Monitor (IWM) was an advanced research activity tracking the emergence of cyberspace as a strategic domain. It closed January 2012. It was a public-private venture between two Canadian institutions: The SecDev Group, an operational think tank based in Ottawa (Canada), and the Citizen Lab at the Munk School of Global Affairs, University of Toronto. The Principal Investigators and co-founders of the Information Warfare Monitor are Rafal Rohozinski (The Secdev Group) and Ronald Deibert (Citizen Lab). The Information Warfare Monitor is part of the Citizen Lab’s network of advanced research projects, which include the OpenNet Initiative, the Fusion Methodology Centre, and PsiLab. It was an independent research effort and its stated mission was to build and broaden the evidence base available to scholars, policy makers, and others. History[edit] Activities[edit] The Information Warfare Monitor engages in three primary activities Case studies. Field-based investigations.

Internet Protocol Suite The Internet protocol suite is the computer networking model and set of communications protocols used on the Internet and similar computer networks. It is commonly known as TCP/IP, because its most important protocols, the Transmission Control Protocol (TCP) and the Internet Protocol (IP), were the first networking protocols defined in this standard. Often also called the Internet model, it was originally also known as the DoD model, because the development of the networking model was funded by DARPA, an agency of the United States Department of Defense. TCP/IP provides end-to-end connectivity specifying how data should be packetized, addressed, transmitted, routed and received at the destination. The TCP/IP model and related protocol models are maintained by the Internet Engineering Task Force (IETF). History[edit] Early research[edit] Diagram of the first internetworked connection Specification[edit] Adoption[edit] Key architectural principles[edit] Abstraction layers[edit] Link layer[edit]

Researchers Discover Twitter-Controlled Bitcoin Bot F-Secure has discovered a bot that commands Twitter accounts to help in the generation of Bitcoins. Security firm F-Secure has discovered a bot that compromises Twitter accounts to help in the generation of Bitcoins. Bitcoin is a decentralized virtual currency that was formed by programmers in 2009, and is generated by programming computers to calculate highly complex math problems. The more computing power you have, the faster you can create Bitcoins; this is why Bitcoin rigs often look like massive sculptures of connected servers. According to an F-Secure blog post, the Twitter-based command below generates a bot that can control the Twitter user's computer and add it to a bitcoin mining rig. Last month Symantec blogged about the potential of creating botnets used to mine bitcoins, without the computer owner ever knowing. Bitcoin has found fans in libertarians, hackers of all shades, computer programmers, and more. For more, see "Which Bitcoin Exchange Can You Trust?"

Telemetry An expendable dropsonde used to capture weather data. The telemetry consists of sensors for pressure, temperature, and humidity and a wireless transmitter to return the captured data to an aircraft. Telemetry is the highly automated communications process by which measurements are made and other data collected at remote or inaccessible points and transmitted to receiving equipment for monitoring.[1] The word is derived from Greek roots: tele = remote, and metron = measure. Systems that need external instructions and data to operate require the counterpart of telemetry, telecommand.[2] Although the term commonly refers to wireless data transfer mechanisms (e.g., using radio, ultrasonic, or infrared systems), it also encompasses data transferred over other media such as a telephone or computer network, optical link or other wired communications like phase line carriers. A telemeter is a device used to remotely measure any quantity. History[edit] Applications[edit] Meteorology[edit]

Heroku | Cloud Application Platform IEC 61131-3 IEC 61131-3 is the third part (of 8) of the open international standard IEC 61131 for programmable logic controllers, and was first published in December 1993 by the IEC. The current (third) edition was published in February 2013. Part 3 of IEC 61131 deals with programming languages and defines two graphical and two textual PLC programming language standards: Data types[edit] (Considering byte size 8 bits) Variables[edit] Variable attributes: RETAIN, CONSTANT, AT GlobalDirect (local)I/O Mapping - Input, Output, I/OExternalTemporary Configuration[edit] Resource - Like a CPUTasks - Can be multiple per CPU.Programs - Can be executed once, on a timer, on an event. Program organization units[edit] Functions Standard: ADD, SQRT, SIN, COS, GT, MIN, MAX, AND, OR, etc.CustomFunction Blocks Standard:Custom - Libraries of functions can be supplied by a vendor or third party.Programs Configuration, resources, tasks[edit] Configuration - processing resources, memory for IO, execution rates, number of tasks.

Amazon Web Services Serial communication In telecommunication and computer science, serial communication is the process of sending data one bit at a time, sequentially, over a communication channel or computer bus. This is in contrast to parallel communication, where several bits are sent as a whole, on a link with several parallel channels. Serial communication is used for all long-haul communication and most computer networks, where the cost of cable and synchronization difficulties make parallel communication impractical. Serial computer buses are becoming more common even at shorter distances, as improved signal integrity and transmission speeds in newer serial technologies have begun to outweigh the parallel bus's advantage of simplicity (no need for serializer and deserializer, or SerDes) and to outstrip its disadvantages (clock skew, interconnect density). The migration from PCI to PCI Express is an example. Cables that carry serial data[edit] Serial buses[edit] Serial versus parallel[edit] See also[edit]

Channel Master CM3000A - Channel Master CM 3000 Suburban Outdoor Amplified Omnidirectional HDTV Channel Master CM 3000 Suburban Outdoor Amplified Omnidirectional HDTV Channel Master CM 3000 Suburban Outdoor Amplified Omnidirectional HDTV Channel Master CM3000 SMARTenna antenna represents the continued advancement of TV reception equipment that customers have come to expect from Channel Master. A unique feature of the SMARTenna TV antenna is its versatility. The antenna provides excellent reception of UHF and VHF television channels when mounted on roofs, walls, chimneys and even inside attics. Features of the Channel Master CM 3000 Suburban Outdoor Amplified Omnidirectional HDTV Specifications for the Channel Master CM 3000 Suburban Outdoor Amplified Omnidirectional HDTV Bandpass 54-806 MHz FM trap (fixed) Attenuates 88-108 MHz Amplifier gain 20 dB Impedance 75 ohm Power required 117 VAC 60 Hz, 4 watts Weatherproof housing UV protected copolymer Box size: L 22.5" H 22" W 2.75" Mounting type Round mast up to 11/2” O.D.

Parallel communication In telecommunication and computer science, parallel communication is a method of conveying multiple binary digits (bits) simultaneously. It contrasts with serial communication, which conveys only a single bit at a time; this distinction is one way of characterizing a communications link. The basic difference between a parallel and a serial communication channel is the number of electrical conductors used at the physical layer to convey bits. Parallel communication implies more than one such conductor. For example, an 8-bit parallel channel will convey eight bits (or a byte) simultaneously, whereas a serial channel would convey those same bits sequentially, one at a time. Examples of parallel communication systems[edit] IBM System/360 Direct Control Feature (1964).[1]:p.18. Comparison with serial links[edit] Before the development of high-speed serial technologies, the choice of parallel links over serial links was driven by these factors: References[edit] See also[edit]

Object-oriented programming Overview[edit] Rather than structure programs as code and data, an object-oriented system integrates the two using the concept of an "object". An object has state (data) and behavior (code). Objects correspond to things found in the real world. So for example, a graphics program will have objects such as circle, square, menu. The goals of object-oriented programming are: Increased understanding.Ease of maintenance.Ease of evolution. The overall understanding of the system is increased because the semantic gap—the distance between the language spoken by developers and that spoken by users—is lessened. Object-orientation takes this to the next step. In addition to providing ease of maintenance, encapsulation and information hiding provide ease of evolution as well. An object-oriented program usually contains different types of objects, each corresponding to a real-world object or concept such as a bank account, a hockey player, or a bulldozer. History[edit] A survey by Deborah J.

How Ethernet Works" Bridges can reduce congestion by allowing multiple conversations to occur on different segments simultaneously, but they have their limits in segmenting traffic as well. An important characteristic of bridges is that they forward Ethernet broadcasts to all connected segments. This behavior is necessary, as Ethernet broadcasts are destined for every node on the network, but it can pose problems for bridged networks that grow too large. When a large number of stations broadcast on a bridged network, congestion can be as bad as if all those devices were on a single segment. Routers are advanced networking components that can divide a single network into two logically separate networks. While Ethernet broadcasts cross bridges in their search to find every node on the network, they do not cross routers, because the router forms a logical boundary for the network. See How Routers Work for a detailed discussion of this technology. How LAN Switches Work" If you have read other HowStuffWorks articles on networking or the Internet, then you know that a typical network consists of: nodes (computers)a connecting medium (wired or wireless)specialized network equipment like routers or hubs. In the case of the Internet, all of these pieces work together to allow your computer to send information to another computer that could be on the other side of the world! ­Switches are another fundamental part of many networks because they speed things up. ­There are many different types of switches and networks.