WHAT IS A FIREWALL ?

A firewall is a part of a computer system or network that is designed  to block unauthorised access while permitting outward communication. Firewalls can be implemented in both hardware and software , or combination of both . A firewall is a dedicated appliance or software running on computer which inspects network traffic passing through it and defines or permits passage based on a set of rules . There are several types of firewall techniques available , they are the followings

Packet-filter

It looks each packet entering or leaving the networks and accept or rejects it based on user defined rules

Application gateway

Applies security mechanisms to specific applications such as ftp,telnet etc

Circuit level gateway

Applies security mechanisms when a tcp or udp connection is established .

Proxy server

Intercepts all messages entering and leaving the network . The proxy server effectively hides the true network address

Read More

STRUCTURE OF LINUX

Linux is a free os which was created by Linus Torvalds at the university of Helsinky in 1991. Torvalds  started linux by creating its kernel partially by using publically available softwares , Then he release the system to his friends , to the internet and asked them to work with it and enhance it. Today 100’s of software developers around the world contributing software to the linux support. Source code of linux operating system is free. Software available for linux was developed by GNU software FSF (free software foundation ) .Structure of linux operating system include

Hardware devices : in any computer system the lowermost layer is the hardware components

Kernel : kernel is known as the core of an operating system , which control the entire operation of the system. Only kernal can directly communicate with hardware

Application programes : an application program may be a word, spread sheet , image editor ,music player etc. these application programes make the use of the computer easily

Shell : shell is an interface through which a user can interact with kernal . all the users in linux system will have their own shell running on the background . all the commands given by users will passed through the shell and interpreted to a form the kernal can understand 

Read More

INTRODUCTION TO LINUX

Linux is a free operating system  which was created by Linus Torvalds at the university of Helsinky in 1991. Torvalds  started linux by creating its kernel partially by using publically available softwares , Then he release the system to his friends , to the internet and asked them to work with it and enhance it. Today 100’s of software developers around the world contributing software to the linux support. Source code of linux operating system is free. Software available for linux was developed by GNU software FSF (free software foundation ) . features of linux include

Multiuser : multiple users can log on to the same linux machine at the same time through different terminals

Multitasking : user can execute more than one program at a time

Network servers : a variety of software packages are available which helps to use linux for different server applications

Application support : there are different application interfaces , built in support for c  c++ , java etc

Hardware support : Hardware support  of linux operating system is very high

Read More

WHAT IS CLOUD COMPUTING ?

Cloud computing is a general term for anything that involves delivering hosted services over the internet .cloud computing is the use of computing resourses such as hardware and software that are delivered as a service over a network typically the internet. The cloud in cloud computing can be defined as the set of hardware ,networks,storage,services and interfaces that combine to deliver aspects of computing as a service . cloud services include the delivery of software , infrastructure and storage over the internet based on user demand.    These services are broadly divided into three categories . they are Infrastructure as a service (iaas), platform as a service (paas) and software as a service (saas). The name cloud computing was inspired by the cloud symbol that’s often used to represent the internet in flowcharts and  diagrams.

                                              

                                                           Cloud computing refers to applications and services offered over the internet . These services are offered from data centers all over the world which collectively are refered to as the cloud  . Examples of cloud computing include online social networking .        

                                                          

Read More

SYMPTOMS OF COMPUTER VIRUSES

Dear  friends in this session we are discussing the points that helps  us to identify  the presence  of computer viruses  in our computer system . The following steps help you to identify the presence of  computer viruses

The computer is slow and takes longer times to load because the computer resources are being used by computer viruses

Abnormal write protect errors on certain files which prevent you from deleting or modifying it

Antivirus software is blocked and not run at all

Strange error message prompt out from time to time

Home of the browser changed , When home page of your favorite browser is changed for no reason , it’s a symptom of virus attack

Unexpected hard drive activity

Unexpected cpu usage  ( in task manager )

Unknown files in the task list ( in task manager)

Read More

HOW TO PREVENT COMPUTER VIRUSES

Dear  friends in this session we are discussing the points that helps  us to prevent  the attack of computer viruses . The following steps help you to protect your computer system by preventing computer viruses

Install a reliable and powerfull Antivirus software , this will help us to prevent the attack of viruses

Never open Email attachments without scanning them first , because email attachments are the most common way the virus are spread through internet

Update your Antivirus at proper times

Try to stay away from cracked softwares  because virus can also spread through cracked softwares

Install a firewall , a firewall is a security mechanism that help us to prevent  unauthorized access

Be aware that most current viruses  arrive as email attachments . Be very suspicious of any attachment that have any of the following extensions

.exe   .vbe   .scr   .vbs   .bat   .shs   .cpl   .dll   .ocx   .pit   .drv   .lnk   .bin    .sys   .eml   .nws

Read More

WHAT IS A ANTIVIRUS

Antivirus software are programs which can detect , prevent and clean up computer viruses which may attempt to infect your computer system. It will scan downloaded files as well as your entire computer system in order to detect  the presence of an infection. Or in other words we can say An Antivirus is a protective software designed to defend your computer system against malicious software or malware  include viruses , Trojans, hijackers etc.The Antivirus software provide real time protection , which means antivirus program protect your computer system from incoming threats. The most antivirus programs have the ability to alert you when a program is trying to access your computer. If an antivirus software find an infected file that cannot be deleted , it can quarantine the file so that it cannot infect other files or programs on your computer  systems. 

Read More

WHAT IS ARTIFICIAL INTELLIGENCE

Artificial Intelligence is the branch of computer science which deals with the study of man made computational devices and systems which can be made to act in a manner which we would be inclined to call intelligent. Alan Turing is Known as the father of Artificial Intelligence . Artificial Intelligence generally involves borrowing characteristics  from human intelligence , and applying them as algorithms in a computer  friendly way . A more or less flexible or efficient  approach can be taken depending on the requirements established, which influence how artificial  the intelligent behaviour appears . Artificial Intelligence can be also defined as the science of making computers  do thing that require intelligence when done by humans. Artificial Intelligence can be also defined as the branch of computer science which deals with the simulation of intelligent behaviour  in computers

Read More

ESSENTIAL WINDOWS COMMANDS

Dear friends in this session we are going to learn some important commands that helps us to perform certain tasks . The following commands helps you to perform ceratin task very simply and easily . The very essential windows commands are

Add or Remove Programs       : Start à Run à  appwiz.cpl

Internet Explorer Settings       : Start à Run à  inetcpl.cpl

Windows Registry Editing       : Start à Run à  regedit.exe

Open Task Manager                 : Start à Run à  taskmgr.exe

To Show The Version Of Windows Currently Installed On The System

                                                    : Start à Run à  winver.exe

View Advanced Information About Hardware And Software Settings

                                                    : Start à Run à  msinfo32.exe

                                                    : Start à Run à  dxdiag

To View System Properties     : Start à Run à  sysdm.cpl

To end a Task                           : Ctrl + Alt + Del

Read More

HOW TO INCRESE THE SPEED OF A COMPUTER SYSTEM

• Make Sure  That Your Computer Hardware is Sufficient
• Free Up Disk Space By Performing Disk Clean up
• Perform Disk Defragmentation To Increase Data Access Speed
• Remove Spyware And Help Protect Your Computer  From Viruses
• Uninstall Unwanted Softwares And Programs
• Adjust Visual Effects for Better Performance
• Install a Effective Anti-Virus Software And Scan For Viruses
• Disable Unnecessary Windows Services
• Clean Your Desktop
• Delete Cookies ,Cache And Internet History From Web Browsers

Read More

WHY WE CANT CREATE A FOLDER NAMED CON ?

In Ms Dos several special  device files were available to aid in performing certain tasks, such as clearing the screen or deleting extraneous output from a program. In order to maintain backwards-compatibility , all versions of windows up to and including  windows 7 will refuse to allow you to create a file with these   “reserved device file names “ . The following names are reserved

     

  CON , PRN , AUX , NUL , COM1 , COM2 , COM3 , COM 4 , COM 5, COM6 , COM7 , COM8 , COM9 ,LPT1 , LPT2 , LPT3 , LPT4 , LPT5 , LPT6, LPT7 , LPT8, LPT9

Read More

HOW COMPUTER VIRUS SPREAD

A Computer Virus is a computer program that can replicate itself and spread from one computer to another . In this Section we can find out how the computer viruses spread , the most common ways of  computer virus spreading are

·        Through Email Attachments , it’s the most common way of virus spreading

·        Through Computer Networks , such as peer to peer network , local area network , wan , wireless network  etc

·        Through virus infected websites

·        Through virus infected softwares and programs

·        Through Hackers , and through internet

·        Through mobile devices

·        Through  External devices such as USB drives , external hard disk , floppy drives etc

Read More

WHAT IS A COMPUTER VIRUS

A Computer Virus is a computer program that can replicate itself and spread from one computer to another . Otherwise we can say computer viruses are small software programs that are designed to spread from one computer to another and to interfere with computer operation. Depends on the nature of a computer virus it may cause damage to your computer system. In most cases if a file that contain virus  is executed or copied onto another computer ,then that computer will also be infected by the same virus. A virus program contains instructions to initiate some sort of event thet affect the infected computer system.  Or simply we can say  a computer virus is a piece of code that is loaded onto your computer without your knowledge and runs against your wishes. 

Read More

HOW TO INCRESE YOUR INTERNET SPEED

Dear friends today we are going to learn how to increase the speed of our internet connection . Microsoft reserves 20% of our available bandwidth for their own purposes like windows update . we can get it back

Start à Run àgpedit.msc à Local Computer Policy à Computer configurationàAdministrative Templates à Network à Qos packet Scheduler à Limit Reservable Bandwidth , Double click on Limit Reversable bandwidth and select Enabled Option and set Bandwidth limit as 0 , Then Apply à Ok

After performing the above steps , check your internet speed 

Read More

HOW TO ENABLE OR DISABLE SWITCH USER MODE IN WINDOWS XP AND 7

IN WINDOWS XP

To Enable

Start à Controll Panel à User Accounts à Change the way users logon or log off àTick use fast user switching à Apply option

To disable

Start à Controll Panel à User Accounts à Change the way users logon or log off àUntick use fast user switching à Apply option

IN WINDOWS 7

To Enable

Start à Run à gpedit.msc à Local Computer Policy à Computer Configuration àAdministrative Templates à System --> Logon à Right click Hide entry points for fast user switching à Edit à Select Not Configured Option à Apply à Ok

To Disable 

Start à Run à gpedit.msc à Local Computer Policy à Computer Configuration àAdministrative Templates à System à Logon à Right click Hide entry points for fast user switching à Edit à Select Enabled Option à Apply à Ok

Read More

WHAT IS A COMPUTER SYSTEM

Computer is a data processing machine which can store , process and retrieve data when ever desired . OR simply we can say ...... C : commonly  O: operating  M: machine    P: particularly    U: used for    T: technical   E: education and   R: research
father of computer : CHARLES BABBAGE   
Charles Babbage , a British mathematics professor is regarded as the father of computer. Charles babbage invented a counting machine called the  difference engine. in those days it took a lot of people to count things , taxes,bankers,areas of finance and markets,all about counting large amounts
father of personal computer : HENRY EDWARD ROBERTS
Henry Edwards Roberts was an American engineer who invented the first commercially successfull personal computer in 1975 . he is most often known as father of personal computer
first computer : ENIAC 
Electronic Numerical Integrator and Computer was the first general purpose electronic computer. ENIAC was  announced in 1946.  ENIAC was designed and built under the supervision of John Mauchly and J Presper Eckert

Read More