Foundation year Lec.4: Lec.4: Communication Software Internet & Security Lecturer: Dalia Mirghani Year : 2014/2015

A set of computers connected together so that they can communicate is called a computer network. This involves installing network cards in each computer. Each computer is then connected through cabling to a central device called a hub. The most commonly used protocol for establishing and maintaining communication across a network is called TCP/IP or Transmission Control Protocol / Internet Protocol. Lecturer: Dalia Mirghani Saadabi2

There are two types of network interconnection: 1) Networks on which all computers have equal status are called peer-to-peer networks. 3

2) Certain computers provide services to other computers, they are called servers. The computers that make use of the services or servers are called clients. A network such as this is called a client server network. 4

1. LAN A LAN or Local Area Network is a group of computers within the same building, or within a group of buildings that are in close proximity, that are connected together. 2. WAN A WAN or Wide Area Network is a group of widely dispersed computers that are connected together. These could be across the same town, or across a country or even across the world. 5

Internet The internet is the collection of all computers across the world which can access each other in some way. The links between computers might include telephone, fiber optic cable, radio, microwave or satellite. Some of its main uses: Provide access to and share information and databases. Transfer and share files between computers. Facilitate business transactions. Share resources. Promote scientific co-operation between research institutions. Provide a communications channel for the military. 6

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INTERNET ACCESS  Using Web browser: A web browser is the software program that is used to display Web pages on the World Wide Web, as Internet explorer and Firefox.  Internet search engine: Is an application, which helps users to locate Web sites containing useful information and references. To search Information :  A user types the description of the information using the user interference of the search engine.  The search engine then searches the requested information on the WWW and returns the results to the user. 8

Some Popular Internet Search Engines 9

Special Medical Search Engines…

Medical Search Engines: Medical search engines are search engines which are specialized in medical information, researches, news and so on. Here are some examples of the most popular medical search engines… 11

Lecturer: Dalia Mirghani Saadabi 12

13 Most Popular medical website:

Information security refers to all the procedures which are used to protect information for deliberate or accidental misuse or dissemination There are a number of procedures companies and persons can take to protect their information. 14

1. Physical procedures: Physical access to mainframes should be restricted to operators and systems administrators. The use of security cameras can also act as a deterrent. 2. Software procedures: Information can be stolen, altered or deleted without the computer being physically removed. The information may even be accessed across the Internet. 15

a) Firewalls: It is a computer program that is installed on a computer that connects a network to the Internet. The firewall analysis the packets that pass in and out of the network. b) Access rights: Information should be classified on the basis of its sensitivity. Access rights to this information should be limited to those who need to know Software rights refer to the level of access different users have to different levels of data and information. 16

c) Password policies: They can be required for access to a computer system or a group of files or a single file. 17

A computer virus is a program that is deliberately created to cause annoyance or alter or delete data. Trojan:  A Trojan (or Trojan horse) is a virus that hides itself inside another legitimate program.  When the program is used, the virus is released and can begin its work of replication and annoyance or damage. 18

Worm:  A Worm is a program that replicates itself over and over in the computer's memory until the computer can barely function.  One of the signs of invasion by a worm is the slowness of computers. 19

Spread of computer viruses: Viruses are spread in a number of ways: – Downloads from the Internet. – Exchange of diskettes. – In attachments to s and in s themselves. 20

Anti-virus software: Anti-virus software scans files for pieces of code, called signatures, which it recognizes as part of a virus. Updating anti-virus software mostly involves updating the signatures file. When a virus is detected, the software will attempt to remove the virus. This is called cleaning or disinfecting. 21

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Lecturer: Dalia Mirghani Saadabi23