What we will learn today: Security Communication

What are the main safety and security issues when using computers? How can data/files be kept safe? 10 Security

Intro to CS. 9/Secure3 Overview 1. Hardware Reliability 2. Backing up your Data 3. Computer Viruses 4. Keeping Data Safe 5. Internet Security

Intro to CS. 9/Secure4 The reliability of a computer component is measured in MTBF (mean time between failures).  hardware is tested in a laboratory  number of failures is divided by total hours of observation It’s better to plan for a hardware failure than hope one doesn’t happen. 1. Hardware Reliability

Intro to CS. 9/Secure5 Downtime - time when a computer is not functioning. Hardware redundancy (maintaining extra equipment) is a popular safeguard used by e- commerce sites. Hardware Failure

Intro to CS. 9/Secure6 A power failure is a complete loss of power to the computer system.  data stored in RAM will be lost A power spike is a brief increase in power  less than one-millionth of a second A power surge lasts a little longer Surges and spikes can damage computers. Power Supply Problems

Intro to CS. 9/Secure7 A UPS (uninterruptible power supply) is the best protection against power failures, surges, and spikes. A UPS contains a battery that keeps your computer running for several minutes during a power failure Uninterruptible Power Supply

Intro to CS. 9/Secure8 A surge strip can protect your computer and other devices from power spikes and surges.  does not contain a battery Surge protector vs. Power strips continued

Intro to CS. 9/Secure9 Don’t mistake a power strip for a surge strip  a power strip provides multiple outlets but cannot protect your computer from power spikes and surges

Intro to CS. 9/Secure10 Copying files, or the contents of am entire disk, provides the best security for your data. Backup tips:  scan for viruses before backing up  make frequent backups (once a day/week)  check the backups  store backups away from your computer 2. Backing up your Data

Intro to CS. 9/Secure11 Consider capacity, speed, and reliability. What to Use for Backups

Intro to CS. 9/Secure12 Backup Software Norton Ghost 9.0 Simply Safe Backup (free)

Intro to CS. 9/Secure13 Use Northern Ghost 8 It is old version, but less than 1.4 MB can run in one floppy disk. It runs under DOS can be used to back up: One disk to another disk, one partition to another partition (usually, Driver C, to Driver D under one disk)

Intro to CS. 9/Secure14

Intro to CS. 9/Secure15

Intro to CS. 9/Secure16 Types of Backups Full backup  copy all the files  safe but can take a long time Differential backup  copy the files that have changed since the last full backup  takes less time but more complex Incremental backup  copy the files that have changed since the last backup

Intro to CS. 9/Secure17 A computer virus is a program that attaches itself to a file, duplicates itself, and spreads to other files. 3. Computer Viruses

Intro to CS. 9/Secure18 The following signs might mean that your computer has a virus:  displays a rude, embarrassing message  unusual visual or sound effects  difficulty saving files  files mysteriously disappear  the computer works very slowly  applications increase in size for no reason Virus Warning Signs

Intro to CS. 9/Secure19 A boot sector virus infects the system files that your computer uses. A macro virus infects a macro. Macros are tiny programs used in word documents, databases, spreadsheets, and many other large applications Virus Types

Intro to CS. 9/Secure20 Macro viruses are the most common. Most Popular Virus Types

Intro to CS. 9/Secure21 Do not get files from high risk sources Use anti-virus software Computer Protection

Intro to CS. 9/Secure22 Don't:  any attachments from your machine  Ignore it, hoping it will go away Do:  tell your system administrator  remove it using anti-virus software  keep anti-virus software updated When a Virus Hits...

Intro to CS. 9/Secure23 Anti-virus software avast! Home Edition (free) Norton AntiVirus

Intro to CS. 9/Secure24 Anti-virus software checks for a virus signature – a unique series of bytes that identifies a known virus inside another program. Hackers keep making new viruses, with new signatures, so anti-virus software needs to be updated regularly.  usually automatically via the Internet Virus Detection Methods

Intro to CS. 9/Secure25 A Trojan horse is a computer program that appears to do something good/useful while actually doing something bad.  not a virus, but may carry a virus  does not duplicate itself Example: a free game available for download from an unknown Web site  it really deletes files once it is started A Trojan Horse

Intro to CS. 9/Secure26 A time bomb is a program that stays in your system undetected until it is triggered by a certain event in time.  e.g. on "Friday 13th" it deletes all your files  usually carried as a virus or in a Trojan horse A Logic bomb is a program triggered by changes to your files.  e.g. every new Word file is deleted Bombs

Intro to CS. 9/Secure27 A software worm is a program designed to enter a computer system through security holes in the computer network. Worms

Intro to CS. 9/Secure28 Good habits:  save files frequently when you are working on them  backup files frequently  use anti-virus software  do not open documents with unknown macros 4. Keeping Data Safe

Intro to CS. 9/Secure29 Acceptable use policy - rules that specify how a computer system should be used  determined by management  used by large organizations  makes users aware of limits and penalties  provides framework for legal action Acceptable Use Policy

Intro to CS. 9/Secure30 User rights - rules that limit directories and files that each user can access.  erase rights  create rights  write rights  read rights  file find rights User Rights

Intro to CS. 9/Secure31 Keep data backups in a locked room, away from the main computing area. Offices with computers should be locked when there is no one around. Computers can be chained to their desks. Restrict Physical Access

Intro to CS. 9/Secure32 Personal identification help identify authorized users:  identity badges  user IDs and passwords  biometrics Personal IDs

Intro to CS. 9/Secure33 Fingerprint scanners can confirm your identity in less than two seconds. Biometric Example

Intro to CS. 9/Secure34 Scramble information so it cannot be understood until it is decrypted. Encryption

Intro to CS. 9/Secure35 Many Internet security problems are due to ActiveX controls  developed by Microsoft to extend the power of Internet Explorer ActiveX controls can be part of Web pages downloaded by Internet Explorer 5. Internet Security and ActiveX continued

Intro to CS. 9/Secure36 ActiveX controls has full access to your computer.  hackers can use ActiveX controls to cause havoc Digital certificates identify the author of an ActiveX control  controls with digital certificates should be safe, if you trust the certificate! Internet Explorer can be configured to reject all ActiveX controls that do not come with certificates.

Intro to CS. 9/Secure37 Most e-commerce sites provide a secure channel for transmitting credit card data. SSL (Secure Socket Layers) uses encryption to establish a secure connection.  SSL pages start with https instead of http. S-HTTP encrypts data one message at a time. Electronic Commerce Security continued

Intro to CS. 9/Secure38 Encrypted messages ensure that credit card numbers cannot be intercepted between a computer and an e-commerce site. During secure transactions, Internet Explorer displays a lock icon and Netscape Navigator displays a key icon.

We look at the basic elements of a communications systems, and the various services available. Communications

Intro to CS. 11/Comm. Systems40 Overview 1. What is a Communications System? 2. Bandwidth 3. Network Topology 4. Protocols 5. Packet Switching 6. Circuit Switching 7. Analog Digital Conversion 8. Telephone Services 9. Cable-based Services 10. Wireless

Intro to CS. 11/Comm. Systems41 A communications system is a combination of hardware, software, and connecting links that transport data between a sender and a receiver. A sender and receiver are linked by a communications channel  e.g. telephone lines, fiber-optic cable 1. What is a Communications System?

Intro to CS. 11/Comm. Systems42 The amount of data that can be sent over a network in a certain period of time. Usually measured in bits per second (bps), kilobits per second (kbps), or megabits per second (mps). Two main types:  broadband (high capacity) e.g. by using fibre-optic cable  narrowband (less capacity) e.g when using the telephone system 2. Bandwidth

Intro to CS. 11/Comm. Systems43 The shape of the interconnections in a communications system is its topology. Star topology - the communications lines fan out from a central location  every connection is dedicated to one user 3. Network Topology continued

Intro to CS. 11/Comm. Systems44 A bus topology provides a common or shared communications link  used by cable TV companies continued

Intro to CS. 11/Comm. Systems45 A ring topology connects devices in a continuous loop  used by older local area networks

Intro to CS. 11/Comm. Systems46 A communications protocol is a set of rules about how a sender and receiver should communicate. The rules specify such things as  data representation, signalling, authentication, and error detection 4. Protocols

Intro to CS. 11/Comm. Systems47 5. Packet Switching Data is separated into small packets. Each packet is sent through the network using the best route available at that time. At the receiving end, the packets are reassembled into the original data. Packet switching is used by the Internet. continued

Intro to CS. 11/Comm. Systems48 1. A message is divided into packets. 2. Each packet is addressed to its destination. 3. A packet might travel the shortest path to its destination. 4. If a route is congested or inoperable, packets can be rerouted to other links. 5. When the packets arrive at their destination, they are reassembled.

Intro to CS. 11/Comm. Systems49 Advantages of Packet Switching Packet switching uses network bandwidth efficently. It minimizes transmission latency  the time it takes for data to pass across the network Packet switching can deal with network failure.

Intro to CS. 11/Comm. Systems50 A dedicated communications path is established between two devices through one or more switching nodes. Unlike packet switching, digital data is sent as a continuous stream of bits. The telephone system uses circuit switching. 6. Circuit Switching

Intro to CS. 11/Comm. Systems51 Advantages of Circuit Switching Bandwidth is guaranteed. Any communication delay is only due to propagation time. Primary advantage of the telephone system for computer communications is that it's cheap for users.

Intro to CS. 11/Comm. Systems52 Telephone systems use miles and miles of twisted-pair cables. Twisted-pair cable terminates with a plastic RJ-45 connector. Twisted Pair Cable

Intro to CS. 11/Comm. Systems53 Old phone lines use analog sound signals. Modern systems use digital signals:  less susceptible to noise  require simpler circuitry It's possible to convert analog signals into digital signals (and vice versa). 7. Analog Digital Conversion

Intro to CS. 11/Comm. Systems54 Analog and Digital Signals

Intro to CS. 11/Comm. Systems55 The Conversion Process Transmission to neighborhood Switch box (within 1800 yards) Neighborhood switch May convert to digital. May remain analog Transmission to city Point of Presence central switch Central office PoP Definitely digital now National Backbone, All digital networks Central office PoP - incoming digital may be converted to analog Neighborhood switch If not analog already, converted at this point Modem in computer Converts analog to digital Transmission to neighborhood switch box (within 1800 yards)

Intro to CS. 11/Comm. Systems56 POTS (plain old telephone service) is an analog service. Voiceband modem - converts digital pulses into analog tones to send digital computer data over a POTS line. 8. Telephone-based Services continued

Intro to CS. 11/Comm. Systems57 ISDN  a standard for digital transmission of voice and data  uses circuit switching with ordinary telephone wire (and other media, such as fibre-optic cable)  it requires hardware adapters at both ends of the transmission  basic (64 kbps); enhanced (128 kbps) continued

Intro to CS. 11/Comm. Systems58 ADSL (Asymmetric Digital Subscriber Line)  for transmitting digital information at a high bandwidth on existing phone lines ADSL offers asymmetric data rates  1.5 to 9 Mbps when receiving (the downstream rate)  16 to 640 Kbps when sending (the upstream rate) Speeds depends on distance from the telephone company office  at most ~3 miles away continued

Intro to CS. 11/Comm. Systems59 T1 Line - provides Mbps send and receive capacity over a dedicated line T3 Line - uses fiber-optic cables to provide service with a capacity of Mbps  the equivalent of 28 T1 lines  enough to show full-screen, full-motion video

Intro to CS. 11/Comm. Systems60 Fiber-optic cable is a bundle of extremely small tubes of glass called optical fibers.  thinner than human hair Fiber-optic cable is replacing twisted-pair cable where high bandwidth is required Fiber-Optic Cable continued

Intro to CS. 11/Comm. Systems61 How fiber-optic cable works:  miniature lasers send pulses of light  each fiber is a one-way communications channel  light signals encounter little resistance

Intro to CS. 11/Comm. Systems62 Cable TV companies in the US have installed miles of high-bandwidth coaxial cables.  carrying capacity far in excess of POTS lines A cable modem is a device designed to demodulate a signal from the cable and translate it back into Internet data. 9. Cable TV-based Services

Intro to CS. 11/Comm. Systems63 Coaxial cable - high-capacity communications cable consisting of a copper wire conductor  common use is to carry television signals Coaxial cable contains shielding which increases bandwidth. Coaxial Cable continued

Intro to CS. 11/Comm. Systems64 Coaxial cable:  has excellent bandwidth, but not as good as fibre-optic cable  more expensive  more difficult to work with than twisted-pair

Intro to CS. 11/Comm. Systems65 Radio-based systems that allow transmission of information without a physical connection,  no need for copper wire or fiber-optic Cellular, infrared, microwave, and satellite broadcasting are forms of wireless communication. Common wireless standards include b, and Bluetooth. 10. Wireless Communications

Intro to CS. 11/Comm. Systems66 Infrared transmissions occur below the visible light of spectrum.  requires line-of-sight communication sender must be able to see the receiver Infrared Wireless

Intro to CS. 11/Comm. Systems67 High-frequency radio waves used for point-to- point and one-directional communication of audio and data. Requires line-of-sight, and ground stations must be within 30 miles of each other. Many communications systems transmit microwave signals between a land-based ground station and a satellite. Microwaves

Intro to CS. 11/Comm. Systems68 Direct satellite service (DSS) uses a geosynchronous or low-earth orbit satellite to send television, voice or computer data directly to a satellite dish.  transmits in one direction – downstream  requires a standard modem and phone line for upstream transmission Satellite

Intro to CS. 11/Comm. Systems is a family of specifications developed by the IEEE for wireless communications.  IEEE = Institute of Electrical and Electronics Engineers b: provide data rates of up to 11 Mbps per second at distances up to approximately 300 feet.  also called Wi-Fi  line-of-sight not required

Intro to CS. 11/Comm. Systems70 Bluetooth An open standard for short-range (30 feet) and low speed (up to 1Mbps) wireless transmission of digital voice and data.  line-of-sight not required  low-power (unlike b), so suitable for portable devices

Intro to CS. 11/Comm. Systems71 Review for Final Exam 1. Read the following three notes: 07.files04. 08IntroductionLinuxOS.pdf 12security09.ppt

Intro to CS. 11/Comm. Systems72 2. Explain the following in essay form. Give your own opinion on the subject. What is Linux? Describe your experience with any Linux Distro you have used? Based on your computer skill and knowledge, provide a solution how to prevent computer virus. As a Buddhist, what are ethical practices in the use of computers? Discuss.