Perang Siber

KETIKA Amerika Syarikat meraikan ulang tahun kemerdekaannya pada 4 Julai lalu,satu siri serangan siber berupa serangan denial-of-service (DDoS) telah dilancarkan ke atas rangkaian Internet di Amerika Syarikat dan Korea Selatan .
Ia menyaksikan kira-kira 25 laman web agensi kerajaan dan syarikat termasuk Rumah Putih,Jabatan Perbendaharaan,Jabatan Pengangkutan,Suruhanjaya Perdagangan Persekutuan,Jabatan Pertahanan,Agensi Keselamatan Nasional,Jabatan Keselamatan Dalam Negeri,Bursa Saham Nasdaq dan New York serta akhbar The Washington Post mengalami gangguan.
Di Korea Selatan,siri serangan tersebut berlarutan sehingga 8 Julai yang menyaksikan 11 organisasi termasuk Pejabat Presiden yang dikenali sebagai Blue House dan Kementerian Pertahanan serta salah sebuah bank terbesar di Korea Selatan,akhbar utama dan agensi perisikannya menjadi sasaran serangan yang mengakibatkan laman web organisasi berkenaan lumpuh atau sukar diakses.
Menurut laporan media,serangan siber ke atas Amerika Syarikat dan Korea Selatan itu didakwa dilakukan oleh Korea Utara.
Jika disoroti insiden serangan siber yang serupa seperti yang dialami oleh Amerika Syarikat dan Korea Selatan baru-baru ini,ia bukanlah kejadian pertama yang berlaku. Estonia (2007),Georgia (2008) dan Kyrgyzstan (Januari 2009) pernah mengalami serangan siber dan yang dituduh menjadi dalang serangan ke atas ketiga-tiga negara itu ialah Rusia.
Persoalannya,apakah benar Korea Utara dan Rusia bertanggungjawab melancarkan perang siber atau ia sekadar hipotesis pihak media dan penganalisis?
Dalam insiden serangan siber ke atas Estonia,Georgia,Kyrgyzstan dan baru-baru ini ke atas Amerika Syarikat dan Korea Selatan,tiada bukti kukuh pembabitan Rusia dan Korea Utara dalam serangan tersebut.
Jika analisis dan hipotesis penganalisis diambil kira,China,Rusia dan Korea Utara adalah antara negara yang mempunyai kekuatan tentera yang terkuat di alam siber.
Rusia dan China adalah dua buah negara yang sering memperagakan keupayaan ketenteraan mereka di alam siber berdasarkan beberapa insiden serangan siber yang didakwa oleh penganalisis-penganalisis keselamatan siber dilancarkan oleh kedua-dua negara berkenaan.
Rusia didakwa memiliki militia siber yang mengawal botnet terbesar di dunia iaitu antara 150 hingga 180 juta nod.
Kebiasaannya,serangan siber berupa DDoS boleh dilancarkan menerusi nod tersebut walaupun nod tersebut tidak berada di negara yang melancarkan serangan. Namun sehingga kini,belum ada bukti kukuh untuk mengaitkan serangan ke atas Estonia,Georgia dan Kyrgyzstan itu dilancarkan oleh militia siber Rusia.
kekuatan ketenteraan
China bukan sahaja merupakan negara yang mempunyai jumlah tentera yang teramai yakni 2.3 juta orang malah di alam siber kekuatan ketenteraan China sering mendapat perhatian kuasa besar dunia seperti Amerika Syarikat dan Britain.
Dalam tahun 2007,ketika serangan siber ke atas Australia dan New Zealand tercetus,China didakwa menjadi dalang serangan tersebut.
Malah,dilaporkan China mempunyai bala tentera siber yang terdiri daripada Tentera Pembebasan Rakyat (PLA) yang sering menceroboh rangkaian komputer di Amerika Syarikat,Kanada,Jerman dan Jepun bagi mengumpul maklumat dan mencuri data penting negara-negara berkenaan.
Namun sehingga ke hari ini,tiada bukti kukuh atas dakwaan tersebut.
Korea Utara yang menyertai China dan Rusia dalam senarai negara yang memiliki tentera siber yang besar didakwa telah bertahun-tahun memiliki sepasukan tentera yang dianggotai oleh kira-kira 100 penggodam yang kebanyakannya adalah graduan akademi tentera di Pyongyang yang bertanggungjawab mengumpul maklumat dan mengganggu jaringan komputer di Korea Selatan dan Amerika Syarikat.
Malah sumber perisikan Korea Selatan pernah mendedahkan bahawa Korea Utara mempunyai 'Unit 121' iaitu satu organisasi ketenteraan yang dianggotai oleh 500-1000 penggodam mahir yang pernah menggodam jabatan pertahanan Korea Selatan dan Amerika Syarikat.
Seperti dalam kes Rusia,segala dakwaan ke atas Korea Utara hanyalah hipotesis penganalisis.
Malah menurut seorang penyelidik botnet,berdasarkan analisis yang dibuat ke atas kod perisian berbahaya (malware) yang digunakan dalam serangan ke atas Amerika Syarikat dan Korea Selatan,tiada penunjuk yang membuktikan serangan tersebut dilakukan atau didalangi oleh Korea Utara.
Jadi,apakah benar Rusia,China dan Korea Utara mampu melancarkan perang siber ke atas musuh mereka seperti yang dilaporkan oleh media barat atau ia sebahagian daripada propaganda politik Amerika Syarikat dalam meneruskan hegemoninya?
Dari satu sudut,memang tidak mustahil negara seperti Rusia,China dan Korea Utara mampu melancarkan perang siber ke atas mana-mana negara yang dimusuhi mereka.
Malah Amerika Syarikat juga mampu melakukannya kerana adalah mustahil sebuah negara maju seperti Amerika Syarikat yang memiliki teknologi dan pakar dalam teknologi maklumat tidak memiliki tentera sibernya sendiri.
Namun ada sesetengah penganalisis insiden serangan siber berpendapat,ada kemungkinan kerajaan atau tentera Rusia,China dan Korea Utara tidak terbabit langsung dalam serangan siber tersebut sebaliknya ia dilakukan oleh penggodam yang mahu menguji kemahiran mereka atau yang bersimpati dan pro negara-negara berkenaan.
Dalam kes insiden di Estonia,Georgia,Kyrgyzstan,Amerika Syarikat dan Korea Selatan,jelas ketegangan geopolitik baik di dalam negara berkenaan mahupun di peringkat antarabangsa dikatakan menjadi punca serangan.
Oleh yang demikian adalah tidak mustahil penggodam yang simpati atau pro pada pihak yang ditekan melancarkan serangan siber terhadap pihak yang menekan atas dasar simpati atau protes.
Ini terbukti dalam insiden serangan siber antara Israel-Palestin yang tercetus pada penghujung 2008 dan awal 2009 di mana isu serangan Israel ke atas Palestin ketika itu mengundang rasa simpati penggodam yang akhirnya menyaksikan kira-kira 12,862 laman web dan 72 pelayan Israel berjaya digodam.
Di Iran,ketika pilihan raya presiden pada pertengahan Jun tahun ini,12 laman web prokerajaan telah menjadi mangsa serangan siber oleh penyokong parti pembangkang,antaranya laman blog rasmi Mahmoud Ahmadinejad,Pejabat Pemerintah Agung Ayatollah Ali Khamenei,Kementerian Dalam Negeri,Polis Kebangsaan,Kementerian Keadilan dan Iranian Press TV.
Insiden serangan siber tersebut berlaku berikutan ketidakpuasan hati penyokong parti pembangkang dengan pemilihan semula Mahmoud Ahmadinejad sebagai presiden.
Penyokong pembangkang menggunakan Twitter sebagai alat komunikasi dan penyebaran maklumat mengenai kaedah untuk menyerang laman web prokerajaan.
Walaupun perang siber masih merupakan hipotesis para penganalisis,insiden serangan siber bukanlah sesuatu yang asing terutama ketika era masa kini yang menyaksikan kebergantungan tinggi manusia terhadap komputer dan Internet.
mengakses komputer
Bagi segelintir daripada kita,kebergantungan terhadap komputer (termasuk telefon bimbit) pada hari ini telah mencapai satu tahap di mana jika tidak mengakses komputer sama ada dengan atau tanpa Internet,kita akan merasa gelisah sepanjang hari.
Daripada urusan pejabat sehingga urusan peribadi dan untuk bersosial,komputer atau telefon bimbit menjadi satu alat yang amat penting bagi mengerjakan segala urusan.
Sesetengah pakar di negara maju berpendapat,kebergantungan yang amat tinggi terhadap komputer (Internet) untuk melakukan apa saja urusan penting boleh mencetuskan cybergeddon yakni situasi di mana pengguna mengalami kesulitan yang boleh mengancam keselamatan apabila komputer atau jaringan Internet mengalami serangan siber.
Serangan siber bukan sahaja boleh mendatangkan kerugian yang besar kepada pengguna Internet malah jika dilancarkan pada skala besar boleh melumpuhkan prasarana kritikal maklumat negara seperti jabatan kerajaan,perbankan,kewangan dan pengangkutan.
Amerika Syarikat sendiri telah mengklasifikasikan serangan siber sebagai ancaman terbesar mereka selepas perang nuklear dan senjata pemusnahan besar-besaran.
Oleh yang demikian,persoalan mengenai sejauh mana serangan siber itu boleh dianggap sebagai satu bentuk perang yang dilancarkan oleh sesebuah negara sebenarnya bergantung pada persepsi penganalisis atau pihak media yang melaporkannya.
Sama ada perang siber akan menjadi satu realiti suatu hari nanti atau kekal sekadar ilusi yang dicipta oleh kuasa besar seperti Amerika Syarikat dalam mengimbangi kebangkitan negara seperti China dan Korea Utara di pentas politik antarabangsa,yang penting insiden serangan siber tidak mustahil akan menjadi senjata perang pada masa akan datang.
Malaysia sebagai sebuah negara yang semakin bergantung pada teknologi maklumat juga harus bersiap siaga untuk mendepani serangan siber.
Redy Jeffry Mohamad Ramli dan Nadia Salwa Mohamad ialah Penyelidik Media Siber di Bahagian Keselamatan Siber dan Polisi,CyberSecurity Malaysia. Kenyataan dan pandangan yang terdapat di dalam artikel ini adalah pandangan peribadi penulis.

KARNIVAL iCT

UBUNTU

Ubuntu (pronounced /uːˈbuːntuː/[4][5] or /uːˈbʌnˌtuː/[citation needed]) is a computeroperating system originally based on the Debian GNU/Linux distribution and distributed as free and open source software with additional proprietary software available.
It is named after the Southern African philosophy of Ubuntu ("humanity towards others").[6] Ubuntu is designed primarily for desktop usage, though netbook andserver editions exist as well.[7] Web statistics suggest that Ubuntu's share of Linux desktop usage is about 50 percent,[8][9] and upward trending usage as a web server.[10]
Ubuntu is composed of many software packages, of which the vast majority are distributed under a free software license (also known as open source). The main license used is the GNU General Public License (GNU GPL) which, along with theGNU Lesser General Public License (GNU LGPL), explicitly declares that users are free to run, copy, distribute, study, change, develop and improve the software. Ubuntu is sponsored by the UK-based company Canonical Ltd., owned by South African entrepreneur Mark Shuttleworth. Canonical creates revenue by sellingtechnical support and services tied to Ubuntu.
Canonical endorses and provides support for three additional Ubuntu-derived operating systems: Kubuntu, Edubuntu, also known as Ubuntu Education Edition, and Ubuntu Server Edition. There are several other derivative operating systems including local language and hardware-specific versions.[11]
Canonical releases new versions of Ubuntu every six months and supports Ubuntu for eighteen months by providing security fixes, patches to critical bugs and minor updates to programs. LTS (Long Term Support) versions, which are released every two years,[12] are supported for three years on the desktop and five years for servers.[13] The latest version of Ubuntu, 10.10 (Maverick Meerkat), was released on October 10, 2010.

Internet, Intranet ,and Extranet

Virus H1N1

Influenza A (H1N1) virus is a subtype of influenza A virus and was the most common cause of human influenza (flu) in 2009. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza. H1N1 strains caused a few percent of all human flu infections in 2004–2005.[1] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).
In June 2009, the World Health Organization declared the new strain of swine-origin H1N1 as a pandemic. This strain is often called swine flu by the public media. This novel virus spread worldwide and had caused about 17,000 deaths by the start of 2010.

In computer networking, topology refers to the layout of connected devices.
Network topology is defined as the interconnection of the various elements (links, nodes, etc.) of a computer network.[1][2] Network Topologies can be physical or logical. Physical Topology means the physical design of a network including the devices, location and cable installation. Logical topology refers to the fact that how data actually transfers in a network as opposed to its physical design.
Topology can be considered as a virtual shape or structure of a network. This shape actually does not correspond to the actual physical design of the devices on the computer network. The computers on the home network can be arranged in a circle shape but it does not necessarily mean that it presents a ring topology.
Any particular network topology is determined only by the graphical mapping of the configuration of physical and/or logical connections between nodes. The study of network topology uses graph theory. Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ in two networks and yet their topologies may be identical.
A Local Area Network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more nodes in the network and the mapping of these links and nodes in a graph results in a geometrical shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flow between the nodes in the network determines the logical topology of the network. The physical and logical topologies may or may not be identical in any particular network.

Network architecture is the design of a communications network. It is a framework for the specification of a network's physical components and their functional organization and configuration, its operational principles and procedures, as well as data formats used in its operation.
In computing, the network architecture is a characteristics of a computer network. The most prominent architecture today is evident in the framework of the Internet, which is based on the Internet Protocol Suite.
In telecommunication, the specification of a network architecture may also include a detailed description of products and services delivered via a communications network, as well as detailed rate and billing structures under which services are compensated.
In distinct usage in distributed computing, network architecture is also sometimes used as a synonym for the structure and classification of distributed application architecture, as the participating nodes in a distributed application are often referred to as a network. For example, the applications architecture of the public switched telephone network (PSTN) has been termed the Advanced Intelligent Network. There are any number of specific classifications but all lie on a continuum between the dumb network (e.g., Internet) and the intelligent computer network (e.g., the telephone network). Other networks contain various elements of these two classical types to make them suitable for various types of applications. Recently the context aware network, which is a synthesis of the two, has gained much interest with its ability to combine the best elements of both.

Computer Network

A computer network, often simply referred to as a network, is a collection of computers and devices connected by communications channels that facilitates communications among users and allows users to share resources with other users. Networks may be classified according to a wide variety of characteristics. This article provides a general overview of types and categories and also presents the basic components of a network.

Format Hardisk

1
When you format a computer hard drive you will lose everything that is on the drive. Therefore, it is very important to back up anything you might want later. Additionally, if you are going to be formatting and installing XP you need to make sure you have the discs for any applications or third party hardware you use since you will need to re-install your programs and drivers after re-installing Windows.
Step 2
Take a moment to think of anything that you have on the computer that you wouldn't want to lose. Generally, you probably want everything in your My Documents folder, and you also want to save things like your favorites or bookmarks from your Web browser. Remember that each user on the computer has his or her own My Documents folder, Desktop items and Favorites/Bookmarks.
Step 3
Save everything to a CD, DVD or a hard drive that you won't be formatting.
Formatting a Secondary Hard Drive
Step 1
Right-Click on the "My Computer" icon either on your desktop or in the Start Menu and select "Manage."
Step 2
A new window titled "Computer Management" comes up. Select "Storage" from the left hand side by clicking it once, then select "Disk Management(local)" from the right side by double-clicking it.
Step 3
Now in the lower part of the main frame (right side) of the window you should see a nice visual of all your hard drives. Each line is a different drive. Each box on a line (with a colored bar at the top and a size displayed in MB or GB) is a partition on the drive. Partitions are separations of space on a drive. Unless you are doing something specific that requires multiple partitions, you only want one partition per drive.
Step 4
First you must delete any existing partitions on the drive you are going to format. Do this by right-clicking on the partition's box and selecting "Delete Partition..." Since you already know that you will be deleting everything on the drive, and have already backed everything up, you can safely say yes to any warning the computer presents you with.
Step 5

jQuery(document).ready(function(){
jQuery('#jsArticleStep5 span.image a:first').attr('href','http://i.ehow.com/images/a00/05/sa/format-hard-drive-2.5-800X800.jpg');
});

If there are multiple partitions make sure you have saved everything off them since they might each have different drive letters (i.e. "D:" or "F:"). Then repeat the above step for each of them. If you only want to format one partition that is OK and you can continue to the next step without deleting the other partitions.
Step 6
The box for the drive to be formatted should now have a black bar at the top of it and should say "Unallocated" under its size (see picture). Right click on it and select "New Partition..." The New Partition Wizard comes up.
Step 7
In the New Partition Wizard click next. On the next page make sure "Primary Partition" is selected and click next. Now make the size equal to the maximum (it should already be set to it), and click next again. On the next page the computer will automatically choose the first available drive letter for the new drive. However, if you like you can choose another drive letter from the drop-down menu, and then click next.
Step 8
Finally the New Partition Wizard asks if you would like to format the new partition and if so what format. Choose "NTFS" as it is faster and more secure. Leave the "Allocation unit size" as "Default." In the "Volume label" field enter whatever name you want the drive to have. Simple is better. Avoid using spaces. Lastly, if the drive is brand new and has never been used before check the "Perform a quick format" box. If the drive has been used before leave this box unchecked. Leave the "Enable file and folder compression" box unchecked and click next. Then on the next page click finish.
Step 9
The wizard will now spend a little while formatting the drive. On old or large drives this may take a while. Do not close the "Computer Management" window until it finishes. You will know it is done when the word under the size of the drive changes from "Formatting" to "Healthy" and the name and drive letter you chose for the new drive show up. After it is finished you can proceed to use your newly formatted drive.

Installation Antivirus

Reboot your system: ’Tis better to have a clean-running system that’s not teetering on the edge of a crash because too many days have passed since the last reboot. (That’s especially a problem on older Windows systems such as Windows 95, Windows 98, or Windows ME.)
Stop all of your other programs: This includes all of the clutter in your systray, half of which you probably don’t need or use anyway.
Read all the way through the antivirus program installation and/or upgrade instructions: Wouldn’t you just hate yourself if Step 46 said to do something that’s really hard to do without a specific preparation that’s only mentioned in Step 46? (I’m not much of a cook, and many times I’ve regretted not reading the recipe all the way through before starting, only to find that I lacked some important ingredient or didn’t have enough time to prepare.)
Take notes: Write down some of the essential things along the way — you may wish you had those little tidbits of data later. A few examples include the name of the directory where you installed the software, and the installation options that you chose.
·Take your time: If you hurry, you’re more likely to skip an important step or make a mistake. It’s more important to install your antivirus software correctly than quickly. You have to live with the results, probably for a long time. Quality doesn’t take shortcuts, and neither should you.
Consider getting help: If installing software feels as intimidating as rebuilding an automobile engine or programming a VCR, then consider having a PC expert help you out, or at least watch over your shoulder and tactfully refrain from snickering to him- or herself.

Installation Office 2007

Typically, when you first try to use a feature that is not installed, the 2007 Office program installs the feature automatically. If the feature that you want is not automatically installed, follow these steps:
Exit all programs.
Click Start, and then click Control Panel.
If you are running Microsoft Windows Vista or Microsoft Windows 7, do the following:
Click Programs, and then click Uninstall a Program.
Click the name of the Microsoft Office Edition 2007 you want to change, and then click Change. In this item, Edition is a placeholder for the edition of Office that you installed.Note In Classic view on Windows Vista or in Icon View on Windows 7, double-click Programs and Features, click the name of the Microsoft Office Edition 2007 you want to change, and then click Change.If you are running Microsoft Windows XP, do the following:
Click Add or Remove Programs.
Click the name of the Microsoft Office Edition 2007 you want to change, and then click Change.Note In Classic view, double-click Add or Remove Programs, click the name of the Microsoft Office Edition 2007 you want to change, and then click Change.
Back to the top
How to repair problems in the installed 2007 Office programs and features
loadTOCNode(2, 'moreinformation');

You can use either of the following methods to detect and to repair problems that are associated with installed Microsoft Office programs and features, such as registry settings and missing installation files. You cannot use these methods to repair personal files.
Method 1: Run Office Diagnostics from a 2007 Office program
loadTOCNode(3, 'moreinformation');

Start the Office Diagnostics tool. To do this, use either of the following methods:
For a menu-based 2007 Office program, click Office Diagnostics on the Help menu.
For a ribbon-based 2007 Office program, follow these steps:
Click the Microsoft Office Button, and then click Program Options.Note In this option, Program represents the name of the program.
In the Navigation Pane, click Resources.
Click Diagnose.
Click Continue.
Click Start Diagnostics. If the Office Diagnostics tool identifies a problem, it tries to fix the problem.
When the Office Diagnostics tool finishes, click Close.

IP Address

An Internet Protocol (IP) address is a numerical label that is assigned to devices participating in a computer network, that uses the Internet Protocol for communication between its nodes.[1] An IP address serves two principal functions: host or network interface identification and location addressing. Its role has been characterized as follows: "A name indicates what we seek. An address indicates where it is. A route indicates how to get there."[2]
The designers of TCP/IP defined an IP address as a 32-bit number[1] and this system, known as Internet Protocol Version 4 or IPv4, is still in use today. However, due to the enormous growth of the Internet and the resulting depletion of available addresses, a new addressing system (IPv6), using 128 bits for the address, was developed in 1995[3] and last standardized by RFC 2460 in 1998.[4] Although IP addresses are stored as binary numbers, they are usually displayed in human-readable notations, such as 208.77.188.166 (for IPv4), and 2001:db8:0:1234:0:567:1:1 (for IPv6).
The Internet Protocol also routes data packets between networks; IP addresses specify the locations of the source and destination nodes in the topology of the routing system. For this purpose, some of the bits in an IP address are used to designate a subnetwork. The number of these bits is indicated in CIDR notation, appended to the IP address; e.g., 208.77.188.166/24.
As the development of private networks raised the threat of IPv4 address exhaustion, RFC 1918 set aside a group of private address spaces that may be used by anyone on private networks. They are often used with network address translators to connect to the global public Internet.
The Internet Assigned Numbers Authority (IANA), which manages the IP address space allocations globally, cooperates with five Regional Internet Registries (RIRs) to allocate IP address blocks to Local Internet Registries (Internet service providers) and other entities.

Colour code

In a bid to become a more trustworthy source, Wikipedia will use color codes to indicate the reliability of an article's author. Called "WikiTrust," the optional feature will assign a color code to newly-edited text, based on the author's reputation.
Famous for its vast number of articles, but not for its reliability, Wikipedia is looking to rehabilitate itself. Starting this fall, text from new or questionable sources will be signalled with a bright orange background, while trusted authors will get a lighter shade.
More than 60 million people visit Wikipedia every month, but because anyone can edit information on the site, credible information is hard to separate from edits by unreliable sources. Wikipedia is so big that Microsoft nearly admitted this was the reason it killed the Encarta encyclopedia.
However, with the new color-coding system in place, the more people view and edit new text on Wikipedia, the more "trust" the initial edits get, turning from orange to white. This way, things that people agree with more often will stick around as reliable information.
The new Wikipedia color-coding feature is built around the WikiTrust tool, which can measure an author's trustworthiness. This is accomplished by looking at how long an author's edit persists over time without objections from other editors. Authors also must build a reputation score between zero and nine, based on their past contributions.
The new color-coding system will be first put in place for articles about living people, as these pages are the most prone to malicious edits. Popular or controversial pages such as the ones for Barak Obama or Britney Spears are already restricted as to who can edit them, so the new color system will be applied to the rest of personality pages.

Straight cable

Category 6 cable, commonly referred to as Cat-6, is a cable standard for Gigabit Ethernet and other network protocols that are backward compatible with the Category 5/5e and Category 3 cable standards. Compared with Cat-5 and Cat-5e, Cat-6 features more stringent specifications for crosstalk and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T / 1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet). Category 6 cable has a reduced maximum length when used for 10GBASE-T; Category 6a cable, or Augmented Category 6, is characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols. Category 6 cable can be identified by the printing on the side of the cable sheath.[1]

Cross Cable (Cat5)

A crossover cable connects two devices of the same type, for example DTE-DTE or DCE-DCE, usually connected asymmetrically (DTE-DCE), by a modified cable called a crosslink. Such distinction of devices was introduced by IBM.
The crossing wires in a cable or in a connector adaptor allows:
connecting two devices directly, output of one to input of the other,
letting two terminal (DTE) devices communicate without an interconnecting hub knot, i.e. PCs,
linking two or more hubs, switches or routers (DCE) together, possibly to work as one wider device.

Internet

The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/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 array of information resources and services, most notably the inter-linked hypertext documents of the World Wide Web (WWW) and the infrastructure to support electronic mail.
Most traditional communications media, such as telephone and television services, are reshaped or redefined using the technologies of the Internet, giving rise to services such as Voice over Internet Protocol (VoIP) and IPTV. Newspaper publishing has been reshaped into Web sites, blogging, and web feeds. The Internet has enabled or accelerated the creation of new forms of human interactions through instant messaging, Internet forums, and social networking sites.
The origins of the Internet reach back to the 1960s when the United States funded research projects of its military agencies to build robust, fault-tolerant and distributed computer networks. This research and a period of civilian funding of a new U.S. backbone by the National Science Foundation spawned worldwide participation in the development of new networking technologies and led to the commercialization of an international network in the mid 1990s, and resulted in the following popularization of countless applications in virtually every aspect of modern human life. As of 2009, an estimated quarter of Earth's population uses the services of the Internet.
The Internet has no centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own standards. Only the overreaching definitions of the two principal name spaces in the Internet, the Internet Protocol address space and the Domain Name System, are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols (IPv4 and IPv6) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely-affiliated international participants that anyone may associate with by contributing technical expertise.

CPU

A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. The cache is a smaller, faster memory which stores copies of the data from the most frequently used main memory locations. As long as most memory accesses are cached memory locations, the average latency of memory accesses will be closer to the cache latency than to the latency of main memory.
When the processor needs to read from or write to a location in main memory, it first checks whether a copy of that data is in the cache. If so, the processor immediately reads from or writes to the cache, which is much faster than reading from or writing to main memory.
The diagram on the right shows two memories. Each location in each memory has a datum (a cache line), which in different designs ranges in size from 8[1] to 512[2] bytes. The size of the cache line is usually larger than the size of the usual access requested by a CPU instruction, which ranges from 1 to 16 bytes. Each location in each memory also has an index, which is a unique number used to refer to that location. The index for a location in main memory is called an address. Each location in the cache has a tag that contains the index of the datum in main memory that has been cached. In a CPU's data cache these entries are called cache lines or cache blocks.
Most modern desktop and server CPUs have at least three independent caches: an instruction cache to speed up executable instruction fetch, a data cache to speed up data fetch and store, and a translation lookaside buffer used to speed up virtual-to-physical address translation for both executable instructions and data.

Virus

A computer virus is a computer program that can copy itself[1] and infect a computer. The term "virus" is also commonly but erroneously used to refer to other types of malware, adware, and spyware programs that do not have the reproductive ability. A true virus can only spread from one computer to another (in some form of executable code) when its host is taken to the target computer; for instance because a user sent it over a network or the Internet, or carried it on a removable medium such as a floppy disk, CD, DVD, or USB drive. Viruses can increase their chances of spreading to other computers by infecting files on a network file system or a file system that is accessed by another computer.[2][3]
As stated above, the term "computer virus" is sometimes used as a catch-all phrase to include all types of malware, adware, and spyware programs that do not have the reproductive ability. Malware includes computer viruses, worms, trojans, most rootkits, spyware, dishonest adware, crimeware, and other malicious and unwanted software, including true viruses. Viruses are sometimes confused with computer worms and Trojan horses, which are technically different. A worm can exploit security vulnerabilities to spread itself automatically to other computers through networks, while a Trojan is a program that appears harmless but hides malicious functions. Worms and Trojans, like viruses, may harm a computer system's data or performance. Some viruses and other malware have symptoms noticeable to the computer user, but many are surreptitious and go unnoticed.