1. System Security Chapter no 16

2. Computer Security Computer security is concerned with taking care of hardware, Software and data The cost of creating data again from scratch can hardware or program lost. Loss of data can have various consequences Bad business decision Loss of goodwill from customers Cash flow problems Adverse publicity from the press Late delivery of goods Failure to receive payment

3. Physical security Computer equipment and its data need to be protected from physical harm These include natural ones such as Fire Lightning Water damage Theft

4. Computer theft There are many ways of making sure that unauthorized people are denied access to a system through use of keyboard locks and password It is more difficult to prevent a thief from picking up a system and stealing it Locks alarmed on circuit board and tags are method of hardware protection

5. Preventing theft Note the serial no of computers and peripherals Lock the computers in case and key should be safely saved Data should be backed up regularly All staff aware of security All staff wear security badge which contains their photograph, name

6. Protection from fires Fireproof doors help contain fire Use Smoke detectors Use gas folding systems are used in large computer installations

7. Protection from dust and extremes of temperature Air conditioning is more important for larger mainframe system where the temperature and humidity must be controlled The air must also be pure and filtered in this way

8. Software Security Viruses Viruses are programs the purpose of which is to disrupt the sensible use of computer. Many viruses do little more than display message on the screen Some are designed to act after a certain period of time which drop off the screen or erased the entire content of hard disk Viruses are able to spread from one disk to other

9. Anti virus software Antivirus software can be used to scan the computer’s memory and disks to detect the viruses Any viruses detected are then removed using the software

10. Avoiding viruses Don’t buy secondhand software Check your computer for viruses if it has been recently repaired Be suspicious of all software which are freeware,shareware Not to use too many computers Install antivirus software which check the hard disk every time the system is booted up

11. Backing up data Means taking the copy of the data and keeping it away from the computer in a secure place. It is not good keeping a back up copy on the same disk The most common way to lose a file is through user error by deleting the file There are software packages available to recover such data

12. Rules of backing up Never keep backup disks near the computer One set of back up disks in a different place If data is expensive to recreate then invest in a fire-proof safe to protect your backups against theft and fire Placing important computer files in safe place so that they can be found easily if needed,which is called archiving

13. Disk failure All micro computers will suffer at least one serious fault during their lifetimes A typical hard disk failures mean time is between 20000 to 200000 hours This mean if computer was used for 12 hr per day then it means that hard disk will break down one about six years If a computer was used for network server then used 24 hr so its mean break down will every 27 months Avoiding disk failure Back up copies of programs and data on a hard disk should be taken at regular interval for this tape streamers is used Floppy disk is also used for backup disk data Use two hard disks in parallel with each other

14. Protecting files Password is keyed in which is never shown in screen Use software to limit each user’s access to only those files that are needed for the performance of their particular job To restrict access to a computer’s OS for inexperienced users Restricted access can also be used to prevent people from copying data from the hard disk to a floppy disk

15. Encryption Files contain sensitive data are encrypted or coded If a tape or disk containing sensitive files is stolen it would then be impossible to read the data without decoder Encryption is also used when important data is transmitted from one place to other The data is coded before being sent and then decoded at the other end. Both processes are performed automatically by computers When people are making payments for goods bought over internet using a credit or debit card the details are always encrypted

16. Data integrity Is concerned with the correctness of the data Errors may be introduced into data in a variety of ways They can be introduced when the person typing in the data misreads it off a source document or if machine errors corrupt the data Validation and verifications checks are performed on data to ensure its integrity

17. Data Security Is concerned with keeping the data safe from the various hazards that could destroy it.

18. Transaction Logs When you make changes to the data in a file you usually delete the old information and replace it with the new information If you have a bank or building society account, money added to your account or taken out needs to be recorded Each bit of business is called transaction The account statement showing the amounts entering and leaving the account shows