Popular Viruses and Worm Programmes

2000            May : The VBS/Loveletter ('ILOVEYOU') worm appeard. As of 2004 this is the most costly virus to business, causing upwards of 10 billion dollars in damage.   2001             January : A worm strikingly similar to the Morris worm, names the Ramen worm infected only Red Hat Linux machines running version 6.2 and 7.                July 13 : The Code Red worm attacking Microsoft Internet Information Services.                October 26 : The Klez worm is first identified.    2003              January 24 : The SQL slammer worm also known as the Sapphire...

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Components of a Virus

A virus comprises of four general components. The replicator (or Engine) : Replicates the virus. The safeguard : Prevents the detection and the removal of the virus. The trigger monitor : Monitors for a specific condition to deliver payload. These specific conditions may be the arrival of a particular date, time, keyboard stroke, etc. The payload : the action it does apart from propagation. This action may be an amusing or malicious action resulting in distraction from the current work or destruction of data....

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Computer Viruses

Some of the main reasons for writing viruses are; Hacking. To prevent copying software. Revenge - Employees may plant "Time Bombs" in programs. Fraud - Viruses may allow access to an otherwise secure system. Political and terrorist motives. Commercial sabotage - Damage the reputation of a competitor. Warfare - Incorporate a virus to an enemy's computer. Viruses can be transmitted from one system to another through various media types such as; Floppy disks. Tape backups. Internet. Software. Some of the symptoms that a computer will show up when infected with a virus are listed below. Programs take long time to lead than normal. The floppy disk drive or hard drive runs when you are not using it. New files keep appearing on the system and you do not know where they come from. Strange...

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Network Protocols

           A network protocol is "an agreement on how to converse". The four most commonly used network protocols are TCP/IP, IPX/SPX, X.25 and SNA. Each protocol performs essentially the same functions, but each protocol is incompatible with other unless there is a special device to translate between them. TCP/IP Network Addressing               TCP/IP protocol uses 3 different types of addressing to move data between computers: Physical, Logical and Port addresses. The physical addresses (MAC addresses) are utilized to move data within a single LAN, logical addresses (IP addresses) are used to move data from one LAN to another LAN across the network and the port address...

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Backbone Network Components

         A backbone network is a network that connects many networks in a single site. There are many backbone network components. Router - A router is a special device that enables the connection of two or more networks so that the computers in different networks can communicate with each other. A router may be a special device, a computer with several network interface cards or a special network module in a computer or other network device. Routers also allow a network to be segmented into smaller logical networks or subnets. Bridge - A Bridge is an interface that enables similar networks to communicate. Gateway - A Gateway is an interface that enables dissimilar networks to...

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Data Transmission Types

       In a network data can be transmitted in two different ways, serial transmission and in parallel transmission. Serial Data Transmission - Bits are transmitted sequentially, one after the other. Parallel Data Transmission - Bits are transmitted through separate channels simultaneously.      The standard unit of measure used to specify the speed of the data flow through a network is bits per second (bps). Network Interface Card (NIC)  A network Interface Card provides the physical connection between the computer and a network cable and enables access to a network. Most modern computers come with NIC cards pre-installed, and ready to be connected to networks.  Types...

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Communication Media

           The communication media is the matter or substance that carries the voice or data. Many different types of transmission media are currently in use. All these different media types can be grouped into two categories: Guided media and Radiated media. Guided Media           The guided media are those in which the data flows through physical media. Twisted-pair Wire - A twisted-pair wire consists of two insulated copper wires, twisted around each other and covered in another layer of plastic insulation. Coaxial Cable - A coaxial cable consists of insulated copper wire wrapped in a metal shield, which is then wrapped in an outer external...

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Network Topologies

           Networks can be laid out in a number of different ways. The physical layout of a network is called its topology. The basic network topologies are Star, Ring, Bus. These basic topologies can be combined in a variety of ways to build complex hybrid network topologies. Star Topology            In a star network all computers and other communications devices are connected to a central point such as a hub, file sever or a host computer. Ring Topology             In a ring network all communications devices are connected in a continuous ring. Messages are passed around the ring until...

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