Ch 16 system security


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Ch 16 system security

  1. 1. 1 System Security Chapter no 16
  2. 2. 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. 3. 3 Physical security  Computer equipment and its data need to be protected from physical harm  These include natural ones such as  Fire  Lighting  Water damage  Theft
  4. 4. 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. 5. 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. 6. 6 Protection from fires  Fireproof doors help contain fire  Use Smoke detectors  Use gas folding systems are used in large computer installations
  7. 7. 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. 8. 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. 9. 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. 10. 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. 11. 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. 12. 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. 13. 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. 14. 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. 15. 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. 16. 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. 17. 17 Data Security  Is concerned with keeping the data safe from the various hazards that could destroy it.
  18. 18. 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