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Tuesday, June 22, 2010

Refleksi Peperiksaan Setengah Tahun 2010

Pagi tadi,Pn Zalina bagi kertas..cuak bila nak dapat kertas..peperiksaan kali ini aku dapat 70 sahaja..sedih..jauh beza dengan markah dulu..tapi tak apa,aku cuba untuk mempertingkatkan lagi usaha...aku kena baca nota lebih awal daripada tarikh periksa ...dan lagi satu,aku kena selalu buat latihan dalam module yang cikgu bagi...

Thursday, May 6, 2010

Storage

Computer storage is the holding of data in an electromagnetic form for access by a computer processor.

FUNCTIONS OF COMPUTER STORAGE.
Computer storage is important to help users store programs and data to be used at a later time.It is also useful to keep current data while being processed by the processor until the information is saved in a storage media such as a hard disk or a diskette.Computer storage also stores instructions from a computer program.

TYPES OF COMPUTER STORAGE

Primary storage is known as the main memory of a computer, including RAM (Random-Access Memory)and ROM (Read-Only Memory). It is an internal memory (inside the CPU) that can be accessed directly
by the processor.
Secondary storage is the alternative storage in a
computer. It is an external storage that refers to various ways a computer can store program and data.

PRIMARY STORAGE
Primary storage is installed internally. Two main types of primary storage are RAM and ROM.
Data from RAM can be read or retrieved and written or stored during processing whereas data from ROM can just be read only.
RAM is volatile, which means the program and data will be lost when the
computer is turned off.
ROM is non-volatile which means it holds the programs and data even when the computer is turned off.
Many complex functions, such as translators for high-level languages and
operating systems are placed in primary storage.

volatile : The content is lost when a computer’s power is turned off.

Secondary storage is an alternative storage. It is very useful to store programs and data for future use. Secondary storage is required for two reasons.
1.The working memory of the CPU is limited in size and cannot always hold the amount of data required.
2.Data and programs in secondary storage do not disappear when the power is turned off.

Central Processing Unit (CPU)

Today I learn about CPU..CPU is the brain of the computer..CPU is an integrated circuit chip that is capable of processing electronic signals..A CPU interprets instruction given by the software and carries out those instruction by processing data and controlling the rest of computer components..

CPU consists two subcomponent : the Control Unit (CU) and the Arithmetic logic Unit(ALU)..Control Units is to direct the CPU to process data..

Under the direction of a program, the Control Unit manages a four-step basic operation which is called a machine cycle or processing cycle.

Fetch and decode is in the instruction cycle whereas execute and store is in the execution cycle. Today’s microprocessor can go through this entire
four-step process billions of times per second.

FETCH
Retrieves the next program instruction from the computer’s memory.

DECODE
Determines what the program is telling the computer to do.

STORE
Stores the results to an internal register (a temporary storage location or to memory).

EXECUTE
Performs the requested instruction, such as adding two numbers or deciding which one of them is larger.

Arithmetic Logic Unit can perform all arithmetic and logical operations. Arithmetic operation is an operation that forms a function of two numbers. This function is usually one of the class of operations: add, subtract, multiply and
divide.

HOW DATA IS PROCESSING??

When a user starts a program, its instructions are transferred from the storage device to the memory. The user enters the data needed by the program.
The Control Unit then interprets and executes instructions in the memory. The Arithmetic Logic Unit then performs calculations on the data in the memory. As a result, information is then stored in the memory. Information can then be sent to an output device or a storage device.

Wednesday, May 5, 2010

MOtHeRbOaRd

Motherboard is the main circuit board on a system unit..motherboard has some electronic components attached to it and others build into it..the expansion cards are slotted in the expansion slot..RAM is the memory of the computer..connectors are plugged into ports..the connector connect to the port..all computer components are connected to its respective port by a connector..

Thursday, April 22, 2010

OVERVIEW OF COMPUTER SYSTEM

These devices are examples of computer hardware. A computer system needs to have these hardware to function.


COMPUTER SYSTEM
A computer system is defined as combination of components designed to process data and store files.

A computer system consists of four major hardware components; input devices, output devices, processor and storage devices.

A computer system requires hardware, software and a user to fully function.

Software refers to set of instructions that tell the hardware what to do. Software can also have various other functions such as performing computation, communication with other software and human interaction.

User refers to a person who uses the computer for any purposes such as work, business and entertainment.

COMPUTER HARDWARE

Computer hardware consists of:
 input devices
 processor
 output devices
 storage devices

Input Devices
Input devices feed data or commands in a form that the computer can use. Example of input devices are:

 Keyboard
 Light Pen
 Joystick
 Microphone
 Mouse
 Video
 Digital camera.

Processor
The CPU is an example of a processor. It has the same important as the brain to human being.

Output Devices
Output devices such as the monitor shows people the process data or information. This type of information can be understood and use by computer user. Other example of output devices are:
 Printer
 Plotter
 Speaker

Storage Devices
Storage usually means secondary storage. It consists secondary storage devices such as hardisk, Floppy Disk, diskette, CD ROM and DVD ROM.

COMPUTER SOFTWARE
There a 2 types of computer software, system software and application software. System software is any computer software that helps to run computer system. System software controls, integrate and manages the individual component of a computer system.

LESSON 28
INTRODUCTION TO COMPUTER SYSTEM

COMPUTER HARDWARE BLOCK DIAGRAM

An Input device feed raw data to the processor. A processor processes raw data and turns it into useful information. A storage device keeps or stores both process and unprocess data for later usage. An output device shows or display the processed data.

INPUT DEVICES


When data is entered into the computer system, it is called an input. Input
comes in various forms; texts, graphics, audio and video. Input devices are
needed to input data into the computer system.

Keyboard, mouse, scanner, barcode reader and digital camera are some example of input devices.

OUTPUT DEVICES
Output is the result of raw input data that has been processed by the central processing unit into meaningful information. Common forms of output are texts, numbers, graphics, sounds, animations and videos.The most common output devices are computer screens, speakers and printers.

STORAGE DEVICES

The system’s primary storage, Random Access Memory (RAM) can only hold data temporarily. Thus, secondary storage is needed to provide additional storage. The data stored in the secondary storage is considered permanent until it is deleted or removed.

Secondary storage can be magnetic disks and optical disks. Examples of secondary storage are hard disks, rewritable CDs and DVDs as well as removable disks such as pen drives.

PERIPHERAL DEVICES

External hardware devices attached to the computer are called peripheral equipments.



LESSON 29
INFORMATION PROCESSING CYCLE

Do you know how a computer works? We use the computer in our everyday lives but not all of us know how this machine operates.

Human uses the brain to think, make decisions and process information. A computer has a brain too, and the brain of a computer is the processor or the central processing unit (CPU) that processes information.

THE CENTRAL PROCESSING UNIT
The central processing unit or the CPU is the brain of the computer.

All processing activities are done in the CPU. It utilises the computer memory to execute instructions from the application software and accomplish a task. For example: editing a letter, drawing a picture and sorting numbers.

The processor must be connected to input devices, output devices and storage devices to carry out the above mentioned tasks.

THE INFORMATION PROCESSING CYCLE

User will input the data to be processed by the processor.

The storage holds databases, files and programs. The output devices
present the processed data as useful information products for the user.

INPUT
Input is any data or instructions that we enter into the computer system for processing.


There are some common ways of feeding input data into the system, which are:

• typing on a keyboard
• pointing with a mouse

CPU accepts instruction from the user and translates the instruction into readable information (decode).

PROCESS
The processing unit controls all activities within the system. For every instruction, the control unit repeats a set of four basic operations called the machine cycle:

Fetching
the process of obtaining a program instructions or data item from memory.

Decoding
the process of translating a program instruction into signals that the computer can execute.

Executing
the process of implementing the instructions in a program.

Storing
the process of writing the result to the storage or memory.


STORAGE
Storage is a location which data, instruction and information are held for future use. Every computer uses storage to hold system software and application software.

When we issue a command to start the application software, the operating system locates the program in storage and loads it into memory.

A storage medium, also called secondary storage is the physical material in the computer that keeps data, instruction and information.

A storage device is the computer hardware that records or retrieves items to and from storage media.

OUTPUT
Output is data that has been processed into a useful form, called information. There are four types of output, which are texts, graphics, audio and video.

The text consists of characters that are used to create texts, sentences and paragraphs.

Graphics are digital representations of non text information such as drawings, charts and photographs.

Audio is music, speech or any other sound. Video consists of images that
provide the appearance of full motion.

LESSON 30
DATA REPRESENTATION


BINARY DIGIT
Computers recognize only two discrete states: on and off. These states can be represented by two digits, 0 and 1. Each 0 or 1 is called a bit in the binary system.

Bit is the smallest unit of data a computer can process. Bit is a short for binary digit. The binary system has a base of 2 with the two digits (0 and 1). Combinations of 0s and 1s represent larger numbers.



BIT
A bit is the smallest unit of data that the computer can process. Bit is a short for binary digit. A bit is represented by the numbers 1 and 0. These numbers represent the binary system. They correspond to the states of on and off, true and false, or yes and no.

All digital data use the binary system to process the information. This information include letters, digits or special character.

BYTE
Byte is a unit of information built from bits. One byte is equals to 8 bits. Eight bits that are grouped together as a unit. A byte provides enough different combinations of 0s and 1s to represent 256 individual characters.

One byte represents a single character such as the number 3, letter b
or a $ symbol. Bits and bytes are the basis for representing all meaningful information and programs on computers.

CHARACTER
8 bits = 1 byte

One byte represents one character such as A, 7, 9 and +.Eight bits that are grouped together as a unit. A byte provides enough different combinations of 0s and 1s to represent 256 individual characters.

For example, the capital letter F is represented by the binary code 01000110 that can be understood by the computer system. Eight bits grouped together as a unit are called a byte. A byte represents a single character in the
computer.

CHARACTER CODES
There are three character codes to represent characters which are ASCII, EBCDIC and Unicode. Each byte contains eight bits. A byte provides enough different combination of 0s and 1s to represent 256 characters.

The combinations of 0s and 1s are defined by patterns. These patterns are called coding scheme. The 256-character capability of ASCII and EBCDIC is too small to handle the characters that are used by other languages such as
Arabic, Japanese and Chinese.

The Unicode coding scheme is designed to solve this problem. It uses two bytes (16 bits) to represent one character. Unicode will have more than 65,000 different characters. This can cover all the world’s languages.

LESSON 31
INTRODUCTION TO BINARY CODING


COMMUNICATION CODES
Smoke signals, Morse code and semaphore are some of the communication codes used by people in the early days. In the information digital era, people send information via electronic devices such as through the computers.

Computers use binary codes to communicate. One of the widely used binary codes is the American Standard Code for Information Interchange (ASCII).

HISTORY OF CHARACTER CODES
Before people used binary codes such as ASCII to communicate via computers, character codes were widely used as a medium of communication. Let’s look at some of the character codes used prior to the use of ASCII.

WHAT IS ASCII?
ASCII pronounced as "ask-key" stands for the American Standard Code for Information Interchange and was proposed by ASA (American Standard Association) in 963 and was finalised in 1968.ASCII is a standard of 7-bit code used to represent characters, which include letters, numbers and punctuation marks.

7 bits allow the computer to encode a total of 128 characters for the numbers 0-9, uppercase and lowercase letters A-Z and a few punctuation symbols. However this 128 bit code only suitable for english language speaking users.

IBM and Apple expanded the amount of space reserved for the character codes to 8-bits, equivalent to 1 byte.

FUNCTIONS OF ASCII
ASCII was established to achieve compatibility between various types of data processing equipment making it possible for the components to communicate with each other successfully.

ASCII enables manufacturers to produce components that are assured to operate correctly in a computer.

ASCII makes it possible for humans to interact with a computer. It also enables users to purchase components that are compatible with their computer configurations.

HOW ASCII WORKS IN A COMPUTER SYSTEM?
When you press a key, for example the letter D on your keyboard, the electronic signal is sent to the CPU for the computer to process and store in memory. Every character is converted to its corresponding binary form. The computer the processes the letter as a byte., which actually a series of on and off of electrical states. When the computer is finished processing the byte, the software installed in the system convert the byte back which is then displayed in the screen. In this example, the letter D is converted to 01000100.

LESSON 32
DATA MEASUREMENT


KILOBYTE (KB)
In mathematics, 1 KB = 1000 bytes.
In computer, 1 KB = 1024 bytes or
can be said as:

1 KB = 210 bytes

This is how we get the calculation for 1024 bytes.


MEGABYTE (MB)
1 MB = 1 048 576 bytes or it can be said as:

1 MB = 220 bytes

GIGABYTE (GB)
1 GB = 1 073 741 824 bytes or it can be said as:

1 GB = 230 bytes

TERABYTE (TB)
1 TB = 1 099 511 627 776 bytes or it can be said as:

1 TB = 240 bytes

LESSON 33
CLOCK SPEED MEASUREMENT

EVOLUTION OF COMMUNICATION
When people talk about a computer’s “speed”, they mean how fast it can process data. In other words, this means the speed the computer can turn data into information.

Every microprocessor contains a system clock. The system clock controls the speed of all the operations within a computer. The speed of the clock is measured by how many cycles per second the clock makes.

HERTZ AND SECONDS
The clock speed unit is measured in hertz. A hertz is one cycle per second.

MEGAHERTZ (MHz)
Mega is a prefix that stands for million. Thus, megahertz (MHz) equals to one million cycles of the system clock. A computer that operates at 933 MHz (megahertz) has 933 million clock cycles in one second.

GIGAHERTZ (GHz)
Giga is a prefix that stands for billion.Gigahertz (GHz) equals to one billion cycles of the system clock.In relation with megahertz,1.0 GHz is equivalent to 1000 MHz.

For example, a microprocessor that runs at 200 GHz executes 200 billion cycles per second. This is what they are talking about if they say a computer is a 2.4 GHz machine. Its clock rate is 2.4 billion cycles per second.
GHz is most often used as a measurement of a PC processor chip and power, with bigger numbers meaning more speed and higher price.

PROCESSING SPEED
The system clock is one of the major factors that influence the computer speed. A CPU with a higher clock speed can process more instructions per second than a CPU with a lower clock speed. For example, a 1 GHz CPU is faster than a CPU operating at 800 MHz. The speed of the system clock affects only the CPU. It has no effect on peripherals such as a printer or disk drive.

MICROPROCESSOR SPEED
One way of comparing the performance of personal computers is by comparing their microprocessor speeds. Microprocessor speeds are determined by their clock speed and are usually expressed in gigahertz (GHz), billion of machine cycles per second.

For example, a personal computer that is listed at 2.2 GHz has a processor capable of handling 2.2 billion machine cycles per second. A top speed personal computer can be much faster, with newer ones exceeding 3.0 GHz.
Direct comparison of clock is meaningful between identical microprocessor.

Thus, it is accurate to say that a Pentium 4 running at 2.4 GHz is approximately one-third faster than a Pentium 4 running at 1.8 GHz.

SPEED AND PATH
The combination of speed and number of paths determines the total processing speed or channel bandwidth. This is because different processors
often use different architectures. For this reason, a 1.4 GHz Pentium 4 performs better than a 1.4 GHz Pentium 3, but it is not as fast as a 1.4 GHz Power PC G4 processor.

COMPUTER SECURITY

DEFINITION OF COMPUTER SECURITY
Computer security means protecting our computer systems and the information they contain against unwanted access, damage, destruction or modification.

We need to protect our computer from any intruders such as hackers, crackers and script kiddie.

We do not want strangers to read our e-mail, use our computer to
attack other systems, send forged e-mail from our computer, or examine personal information stored on our computer such as financial statements.

TYPES OF COMPUTER SECURITY
Three types of computer security are:

a) hardware security
b) software security/data security
c) network security


a) HARDWARE SECURITY
Hardware security refers to security measures used to protect the hardware specifically the computer and its related documents.

The examples of security measures used to protect the hardware include PC-locks, keyboard-locks, smart cards and biometric devices.

b) SOFTWARE AND DATA SECURITY
Software and data security refers to the security measures used to protect the software and the loss of data files.

Examples of security measures used to protect the software are activation code and serial number.

An example of security measure used to protect the loss of data files is the disaster recovery plan method. The idea of this plan is to store data, program and other important documents in a safe place that will not be affected by any major destruction.

c) NETWORK SECURITY
The transfer of data through network has become a common practice and the need to implement network security has become significant.

Network security refers to security measures used to protect the network system. One example of network security measures is firewall. With firewall, network resources can be protected from the outsiders.

PERSONAL COMPUTER SECURITY CHECKLIST
In order to make sure our computers are secured, here are the computer
security checklist to follow.

 Do not eat, drink or smoke near the computer
 Do not place the computer near open windows or doors
 Do not subject the computer to extreme temperatures
 Clean the equipment regularly
 Place a cable lock on the computer
 Use a surge protector
 Store disks properly in a locked container
 Maintain backup copies of all files
 Stores copies of critical files off sites
 Scan a floppy disk before you open it
 Do not open any unknown email received

LESSON 17
INTRODUCTION COMPUTER THREATS

The computer is a great tool to store important information. In certain cases, the information is very vital that losing it will harm the computer system.

Computer threats can come from many ways either from human or natural disasters. For example, when someone is stealing your account information from a trusted bank, this threat is considered as a human threat. However, when your computer is soaked in heavy rain, then that is a natural disaster threat.




MALICIOUS CODE
Malicious code is also known as a rogue program. It is a threat to computing assets by causing undesired effects in the programmer’s part. The effect is caused by an agent, with the intention to cause damage.

The agent for malicious code is the writer of the code, or any person who causes its distribution. There are various kinds of malicious code. They include virus, Trojan horse, logic door, trapdoor and backdoor, worm and many others.

a) VIRUS
• a program that can pass on the malicious code to other programs by modifying them

• attaches itself to the program, usually files with .doc, .xls and .exe extensions

• destroys or co-exists with the program

• can overtake the entire computing system and spread to other systems

b) TROJAN HORSE
• a program which can perform useful and unexpected action

• must be installed by users or intruders before it can affect the system’s assets

• an example of a Trojan horse is the login script that requests for users’ login ID and password

• the information is then used for malicious purposes

c) LOGIC BOMB
• logic bomb is a malicious code that goes off when a specific condition occurs.

• an example of a logic bomb is the time bomb

• it goes off and causes threats at a specified time or date

e) TRAPDOOR OR BACKDOOR
• a feature in a program that allows someone to access the program with special privileges

f) WORM
• a program that copies and spreads itself through a network

Primary Differences Between Worms And viruses
Worm Virus
Operates through the network Spreads through any medium
Spreads copies of itself as a standalone program Spreads copies of itself as a program that attaches to other
programs

HACKER
Hacking is a source of threat to security in computer. It is defined as unauthorised access to the computer system by a hacker.

Hackers are persons who learn about the computer system in detail. They write program referred to as hacks. Hackers may use a modem or cable to hack the targeted computers.

NATURAL AND ENVIRONMENTAL THREATS
Computers are also threatened by natural or environmental disaster. Be it at home, stores, offices and also automobiles.Examples of natural and environmental disasters:
 Flood
 Fire
 Earthquakes, storms and tornados
 Excessive Heat

THEFT
Two types of computer theft:

1) Computer is used to steal money, goods, information and resources.
2) Stealing of computer, especially notebook and PDAs.

Three approaches to prevent theft:

1) prevent access by using locks, smart-card or password
2) prevent portability by restricting the hardware from being moved
3) detect and guard all exits and record any hardware transported

LESSON 18
SECURITY MEASURES

Today, people rely on computers to create, store and manage critical information. It is important that the computer and the data they store are accessible and available when needed. It is also important that users take measures to protect their computers and data from lost, damage and misused.

Security measures mean the precautionary measures taken toward possible danger or damage. There are 6 type of security measures.

1) DATA BACKUP
Data Backup is a program of file duplication. Backups of data applications are necessary so that they can be recovered in case of an emergency.

Depending on the importance of the information, daily, weekly or biweekly backups from a hard disk can be performed.

2) CRYPTOGRAPHY
Cryptography is a process of hiding information by altering the actual information into different representation, for example, an APA can be
written as I? X.

Almost all cryptosystems depend on a key such as a
password like the numbers or a phrase that can be used to encrypt or decrypt a message.

The traditional type of cryptosystem used on a computer network is called a symmetric secret key system.

3) ANTIVIRUS
An antivirus program protects a computer against viruses by identifying and removing any computer viruses found in the computer memory, on
storage media or incoming e-mail files.

An antivirus program scans for programs that attempt to modify the boot program, the operating system and other programs that normally are read from but not modified.

IDENTIFYING VIRUS
Two technique are used to identify the virus.

VIRUS SIGNATURE INOCULATING A PROGRAM FILE
Also called a virus definition is a specific pattern of the virus code. The antivirus program records
information such as the file size and file creation date in a separate inoculation file.

The antivirus program then uses this information to detect if a virus tampers with the data describing the inoculated program file.

If an antivirus program identifies an infected file, it attempts to remove its virus, worm or Trojan horse. If the antivirus program cannot remove the infection, it often quarantines the infected file. Quarantine is a separate
area of a hard disk that holds the infected file until the infection can be removed. This step ensures other files will not become infected. Patents for inventions Utility, design or plant patents that protect inventions and improvements to existing inventions

4) ANTI-SPYWARE
Spyware is a program placed on a computer without the user’s knowledge. It secretly collects information about the user.

The spyware program communicates information to
the outside source.

An anti-spyware application program sometime called tracking software or a spybot is used to remove spyware.

Among of the popular anti-spyware programs are:

• Spybot Search and Destroy
• Ad-aware
• Spyware Blaster

5) FIREWALL
Firewall is a piece of hardware or software which functions in a networked environment to prevent some communications forbidden by the security
policy.

Firewall implement a security policy. It might permit limited access from in or outside the network perimeters or from certain user or for certain activities.

6) HUMAN ASPECTS OF SECURITY MEASURES
Human aspects refer to the user and also the intruder of a computer system.

It is one of the hardest aspects to give protection to.

The most common problem is the lack of achieving a good information security procedure.

LESSON 19
RELATIONSHIP BETWEEN SECURITY THREATS AND SECURITY MEASURES

Security threats may come from in many forms. For example, when someone is invading your account information from a trusted bank, this act is considered as a security threat.

Security measures can be used to prevent this invader from getting the account information. For example, the bank can use a firewall to prevent unauthorised access to its database.

SECURITY THREADS
Security threats may come from in many forms. For example, when someone is invading your account information from a trusted bank, this act is considered as a security threat.

Security measures can be used to prevent this invader from getting the account information. For example, the bank can use a firewall to prevent
unauthorised access to its database.

MALICIOUS CODE THREATS VS. ANTIVIRUS AND ANTI-SPYWARE
Security threats include virus, Trojan horse, logic bomb, trapdoor and backdoor, and worm.

Antivirus and anti-spyware can be used to protect the computer from the threats by:

 limiting connectivity
 allowing only authorised media for loading data and software
 enforcing mandatory access controls
 blocking the virus from the computer program

HACKING VS. FIREWALL
Hacking is an unauthorised access to the computer system done by a hacker. We can use firewall or cryptography to prevent the hacker from accessing our computers.

A firewall permits limited access to unauthorised users or any activities from the network environment. Cryptography is a process of hiding information by changing the actual information into different representation, for example, an APA can be written as 7&*.

NATURAL DISASTER VS. DATA BACKUP
The natural and environmental disasters may include:
• flood
• fire
• earthquakes
• storms
• tornados

Natural disasters may threaten a computer’s hardware and software easily. Computers are also sensitive to their operating environment such as
excessive heat or the inadequacy of power supply.

The backup system is needed to backup all data and applications in the computer. With the backup system, data can be recovered in case of an emergency.

THEFT VS. HUMAN ASPECTS
Computer theft can be of two kinds:

 can be used to steal money, goods, information and computer resources
 the actual stealing of computers, especially notebooks and PDAs


Measures that can be taken to prevent theft:

 prevent access by using locks, smart-card or password
 prevent portability by restricting the hardware from being moved
 detect and guard all exits and record any hardware transported

BE SUPSPICIOUS OF ALL RESULTS
There are many instances where non-programmers develop applications which are not built with proper understanding of software engineering practices.

Data produced by such applications may not be correct and may risk corrupting data received from other sources that are not compatible with the application.

LESSON 20
SECURITY PROCEDURES

Computers should have alarm systems to guard them from any attacks such as viruses and data corruption. The alarm system is the security measures that we take to ensure its safety.

DATA PROTECTION
We need to protect the data in the computer as it may somehow get lost or corrupted due to some viruses or mishap like fire, flood, lightning, machine
failures and even human errors.

There are a few ways to protect the information namely:
• make backup files
• detect the virus and clean the computer
• warn others on virus attacks

1) BACKUP FILES
Users can do backups of file systems by:
 keeping the duplicated files in external storage such as in the floppy disk and thumb drive
 do backup frequently


2) DETECT VIRUS AND DO CLEANUP
A computer virus is able to affect and infect the way the computer works. Viruses can be detected when we run an antivirus program.We can also delete the infected files and documents.

3) WARN OTHERS ON VIRUS ATTACK
We can warn others on virus attacks or new viruses by sending e-mails to them.

DETECTING ILLEGAL ACCESS TO SYSTEMS
The computer system is able to detect any illegal access to the system by a user who does not have any authorisation. Basically, a corporation will simply use tcpwrappers and tripwire to detect any illegal access to their system. User's access will be reviewed periodically by computer operations. On going internal audits will be made to ensure detection of violations of security and unauthorised modifications to software and data .

TCPWRAPPERS

Tcpwrappers stop the attempted connection

examines its configuration files
will decide whether to accept or reject the request.

Tcpwrappers will control access at the application level, rather than at the socket level like iptables and ipchains. The system will run tcpwrappers to log access to ftp, tftp, rch, rlogin, rexec and telnet.

TRIPWIRE
Tripwire will detect and report on any changes in the thousands of strategic system files.

The system will run tripwire to determine if system files have changed.

PREVENTING ILLEGAL ACCESS TO SYSTEMS
Have any of you ever been to an airport? Do you know the do’s and don’ts when you are at the airport?

There are things that cannot be taken inside the airplane. It is for the purpose of security procedures.

It is the same as computer systems. It would not allow any unauthorised users to simply access the system.

Ways to prevent illegal access to systems:

1. Run anlpassword to make password cracking difficult.
2. Run tcpwrappers to check if the name for an ip address can be provided by DNC
3. Use a callback system to prevent unauthorised use of stolen passwords.

PREVENTING ILLEGAL ROOT ACCESS
To prevent any illegal root access, we should have Sudo, so that people can perform on some machine without getting access to the entire root if that is not required. In addition, with Sudo we did not have to give out the root password.

Sudo stands for (Superuser do) and is a program in Unix, Linux and similar operating systems such as Mac OS X that allows users to run programs in the form of another user (normally in the form of the system's superuser).

Sudo allows a permitted user to execute a command as the superuser or another user, as specified in the sudoers file.

PATCH
Patch supplies small updates to software, provided that the source code is available.

Patch is a name of an UNIX utility. It applies a script
generated by the different program to a set of files
that allows changes from one file to be directly applied to another file.

Resources are not enough to patch all security holes that we hear about through the bugtraq list.

(Bugtraq is a full disclosure mailing list dedicated to the issues of computer security. On-topic discussions are new discussions about vulnerabilities, methods of exploitation and how to fix them. It is a high volume
mailing list and almost all new vulnerabilities are discussed there.)

Reflection About Penilaian Kurikulum 2

I has sit for ICT exam last week..It has 3 section where section A has 33 marks, section B has 10 marks and section C has 7 marks..So I has answered all the question that has given..The question does not difficult..But not all my answer was correct..

Last Tuesday,Cik Asmahani give back my ICT paper..I was disappointed with the marks..If I can get 2 marks more, I will get A+..But I very happy because my marks getting better than PK1..When I went home, I were thinking about that..I should read and do more revision.. After that,I should more pay attention in class when teacher was teaching..I should ask teacher and my friends about the topic that I not understand..I hope in the Mid Year examination,I can get A+ because I CAN DO IT!!!!