Brute-force attack The EFF's US$250,000 DEScracking machine contained over 1,800 custom chips and could brute-force a DES key in a matter of days. The photograph shows a DES Cracker circuit board fitted on both sides with 64 Deep Crack chips. When password guessing, this method is very fast when used to check all short passwords, but for longer passwords other methods such as the dictionary attack are used because of the time a brute-force search takes. When key guessing, the key length used in the cipher determines the practical feasibility of performing a brute-force attack, with longer keys exponentially more difficult to crack than shorter ones. Brute-force attacks can be made less effective by obfuscating the data to be encoded, something that makes it more difficult for an attacker to recognize when he/she has cracked the code. Brute-force attacks are an application of brute-force search, the general problem-solving technique of enumerating all candidates and checking each one. Unbreakable codes[edit]
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]
WinRoute :: Example of VPN tunnel configuration This chapter provides a detailed exemplary description on how to create an encrypted tunnel connecting two private networks using the Kerio VPN. This example can be easily customized. Note: This example describes a more complicated pattern of VPN with access restrictions for individual local networks and VPN clients. An example of basic VPN configuration is provided in the Kerio WinRoute Firewall Step By Step Configuration document. Specification Supposing a company has its headquarters in New York and a branch office in Chicago. The server (default gateway) of the headquarters uses the public IP address 63.55.21.12 (DNS name is newyork.company.com), the server of the branch office uses a dynamic IP address assigned by DHCP. The local network of the headquarters consists of two subnets, LAN 1 and LAN 2. The network of the branch office consists of one subnet only (LAN). VPN clients can connect to the LAN 1 and to the network of the branch office. Headquarters configuration VPN test
Krebs on Security 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]
Aplicaciones en capas La estrategia tradicional de utilizar aplicaciones compactas causa gran cantidad de problemas de integración en sistemas software complejos como pueden ser los sistemas de gestión de una empresa o los sistemas de información integrados consistentes en más de una aplicación. Estas aplicaciones suelen encontrarse con importantes problemas de escalabilidad, disponibilidad, seguridad, integración... Para solventar estos problemas se ha generalizado la división de las aplicaciones en capas que normalmente serán tres: una capa que servirá para guardar los datos (base de datos), una capa para centralizar la lógica de negocio (modelo) y por último una interfaz gráfica que facilite al usuario el uso del sistema. Figura 3.1. Si intentamos aplicar esto a las aplicaciones web, debido a la obligatoria sencillez del software cliente que será un navegador web, nos encontramos con una doble posibilidad: La arquitectura MVC y Model 2
How to protect your PC against devious security traps Securing your PC against the malicious wilds of the Web isn’t as simple as just keeping your antivirus software of choice up-to-date. In fact, the pervasiveness of security software has forced the bad guys to turn to increasingly clever tricks in their quest to “pwn” your PC. But fear not! Those sneaky tricks are most effective if victims are unaware of the danger. Phishing Let’s start with the devious attack you’re most likely to encounter during your day-to-day computing. Phishing websites mimic the look of another site in an attempt to lure you into entering your personal and account information. One simple tell gives away a phishing site: The URL doesn’t match the URL of the website you think it is. Beyond that, most social media and banking websites use HTTPS encryption by default. Malicious email Scammers and hackers love email. Okay, that’s not quite true. Though not all malicious email messages originate from foreign lands and contain spelling and grammar mistakes, many do. OMG hax
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.
TEL&PC Ltda. La Red Privada Virtual (RPV), en inglés Virtual Private Network (VPN), es una tecnología de red que permite una extensión de la red local sobre una red pública o no controlada, como por ejemplo Internet. Ejemplos comunes son, la posibilidad de conectar dos o más sucursales de una empresa utilizando como vínculo Internet, permitir a los miembros del equipo de soporte técnico la conexión desde su casa al centro de cómputo, o que un usuario pueda acceder a su equipo doméstico desde un sitio remoto, como por ejemplo un hotel. Todo ello utilizando la infraestructura de Internet. Para hacerlo posible de manera segura es necesario proporcionar los medios para garantizar la autenticación, integridad y confidencialidad de toda la comunicación: Autenticación y autorización: ¿Quién está del otro lado? Integridad: La garantía de que los datos enviados no han sido alterados.
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]
Redes - Arquitectura Cliente/Servidor en 3 niveles Abril 2014 Introducción a la arquitectura en 2 niveles La arquitectura en 2 niveles se utiliza para describir los sistemas cliente/servidor en donde el cliente solicita recursos y el servidor responde directamente a la solicitud, con sus propios recursos. Introducción a la arquitectura en 3 niveles En la arquitectura en 3 niveles, existe un nivel intermediario. Un cliente, es decir, el equipo que solicita los recursos, equipado con una interfaz de usuario (generalmente un navegador Web) para la presentaciónEl servidor de aplicaciones (también denominado software intermedio), cuya tarea es proporcionar los recursos solicitados, pero que requiere de otro servidor para hacerloEl servidor de datos, que proporciona al servidor de aplicaciones los datos que requiere Comparación entre ambos tipos de arquitecturas Arquitectura de niveles múltiples En la arquitectura en 3 niveles, cada servidor (nivel 2 y 3) realiza una tarea especializada (un servicio). Véase también
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]
Aplicaciones ERP: Sistema de Gestión Integrado La gestión clásica de información en una empresa poco moderna, suele aplicar un software diferente en cada departamento: finanzas, almacenes, recursos humanos, etc. Las inevitables consecuencias de dicha dispersión de datos y formatos dan lugar a una pérdida de tiempo e información de incalculable valor y a la larga es más costoso no adoptar un sistema integrado que seguir en la misma situación. Por ejemplo, si un cliente hace un pedido al departamento de ventas, éste lo registrará en un sistema de información exclusivo de ventas; en consecuencia, ni el departamento de finanzas podrá controlar si dicho cliente tiene un crédito, ni el departamento de almacenes podrá verificar si existe material suficiente para poder suministrar el pedido. Por tanto, estos datos tendrán que comunicarse por vía telefónica o por medio de un documento escrito a los respectivos departamentos para que éstos realicen sus labores y cumplan con culminar el ineficiente proceso de la venta. 1. 2. 3. 1. 2. 3. 4. 1.
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.