CIE Networks and the Effects of Using Them PDF

Chapter (4): Networks and the effects of using them  Contents Networks Network issues and communication Networks  What is a Network? A network is two or more computers, or other electronic devices, connected together so th...

Chapter (4): Networks and the effects of using them  Contents Networks Network issues and communication Networks  What is a Network? A network is two or more computers, or other electronic devices, connected together so that they can exchange data. For example, a network allows:  Computers to share files  Users to message each other  Share Resources Network connections between computers are typically created using cables (wires) or via wireless signals. Advantages of using Networks Easily share files and data. Share resources such as printers and Internet connections. Communicate with other network users (e-mail, instant messaging, video-conferencing, etc.) Store data centrally (using a file server) for ease of access and back-up. Keep all of our settings centrally so we can use any workstation. Disadvantages of using Networks Greater risk of hackers. Greater risk of viruses (spreading and disabling network). The significant cost of extra equipment. When the network is down computers can not be used as standalone computers. Print queues can be long.  Common network devices and terms  Network interface card (NIC) NIC is needed to allow a device to connect to a network. It turns binary data into an electrical signal that allows access to a network. Each NIC is given a unique hardwired (or hard-coded) media access control (MAC) address at the manufacturing stage. Wireless network interface cards (WNICs) use wireless connectivity, utilising an antenna to communicate with networks via microwaves.  Media access control (MAC) address is a number which uniquely identifies a device when it is connected to a network is made up of 48 bits which are shown as six groups of hexadecimal digits is sometimes referred to as the physical address because it where the first six hex digits identify uniquely identifies a device a device made by Apple and the second set of six hex digits are the MAC addresses are useful when trying to identify network unique serial number of the device faults because they never change, which makes it a more reliable method of identifying data senders and data receivers on a network.  Internet protocol (IP) addresses Each device on the internet is given a unique address known as its internet protocol (IP) address. This is usually assigned to the computer by the internet service provider (ISP). An IP address identifies the location of a device on a network. There are two versions of IP: IPv4 and IPv6. IPv4 is based on 32-bit number (four groups of eight bits) that is usually written in the for 109.108.158.1 IPv6 is based on 128-bit number (eight groups of hex digits) that is usually written in the form: A8FB:7A88:FFF0:0FFF:3D21:2085:66FB:F0FA Q. What is the difference between an IP address and a MAC address? The IP address gives the location of a device on the internet, whereas the MAC address identifies the device connected to the internet.  Data packets Data is moved around networks in the form of data packets. Packets of data usually contain the following information:  the sender's IP address  the receiver's IP address  the sequence/identity number of the packet  the packet size  how many data packets make up the whole 'message'  Modems Modems convert analogue signals from a telephone line to digital signals which can be read by the computer. The Modem also converts digital signals back into analogue for transmission over telephone lines.  Dial-up modems operate at transmission speeds of about 60 kilobits* per second  ADSL (asymmetric digital subscriber line) modems operate at up to 100 Megabits* per second  A Hub and a Switch both connect a number of computers together to make a LAN.  Hubs A hub will take a data packet received at one of its ports and broadcast it to every device connected to it. Poor Security because every device will receive every data packet Only would be suitable for a small home networks ( local area network (LAN)).  Switches Sends specific packets of data to specific computer(s) only on the LAN using workstations unique MAC addresses. switch uses a look-up table to determine the destination device More secure however more expensive Normally used in larger networks found in schools, offices etc.  Bridges Bridges are devices that connect one LAN to another LAN that uses the same protocol (communication rules). They are often used to connect together different parts of a LAN so that they can function as a single LAN. Bridges cannot communicate with other external networks, such as the internet.  Router Routers enable data packets to be routed between the different networks, for example to join a LAN to a wide area network (WAN). The router's main function is to transmit internet and transmission protocols between two networks and also allow private networks to be connected together. Routers direct packets of data across the internet to its destination. Everything connected to the internet has an IP Address. Router is able to send the data packet to the appropriate switch and it will then be delivered using the MAC destination address.  Comparison of routers and bridges Router Bridge The main objective of a router is to connect various types The main objective of a bridge is to connect of network together LANs together Routers scan a device’s IP address Bridges scan a device’s MAC address Data is sent out using data packets Data is sent out using data packets Connected networks will use different protocols Connects networks together that use the same protocols A routing table is used to direct data packets to the Bridges do not make use of routing tables correct device A router has more than two ports A bridge has only two ports Tick (✓) the appropriate box to indicate whether it refers to a router, hub or switch.  Other Hardware  Gateway A gateway is a network point ( or node) that acts as an entrance to another network.  Network cables Many computer systems use wi-Fi, network cables are still used because they have the following advantages over Wi-Fi: faster data transfer rates can be more secure than wireless networks. The cables can be either copper or fibre optics - offers higher data transfer rates and better security.  Wi-Fi and Bluetooth Both Wi-Fi and Bluetooth offer wireless communication between devices. They both use radio frequencies as the carrier of data transmission.  Wi-Fi A wireless transmitter (WAP) receives information from a network via its connection. This transmitter converts the received information into radio waves and then transmits them. A device (e.g. a computer) receives the radio waves via an installed wireless adaptor which allows it to download the information from the data source. It offers much faster data transfer rates, better range and better security than Bluetooth. Can access, the internet wirelessly at any access point (AP) or hot spot up to 100m away.  Wi-Fi and Bluetooth  Bluetooth Bluetooth sends and receives radio waves in a band of 79 different frequencies (known as channels). If the channel is already being used, it randomly picks another channel. This is known as spread-spectrum frequency hopping. It is useful - when transferring data between two or more devices that are very close together - for low-bandwidth applications Bluetooth creates a secure wireless personal area network (WPAN) based on key encryption.  Cloud computing (storage) Cloud computing is a method of data storage where data is stored on remote servers – there may be thousands of servers in many different locations. The same data is stored on more than one server in case of maintenance or repair, allowing clients to access data at any time. This is known as data redundancy.  There are three common cloud storage systems:  Public cloud – this is a storage environment where the customer/client and cloud storage provider are different companies.  Private cloud – this is storage provided by a dedicated environment behind a company firewall; customer/client and cloud storage provider are integrated and operate as a single entity.  Hybrid cloud – this is a combination of the two previous environments; some data resides in the private cloud and less-sensitive/less-commercial data can be accessed from a public cloud storage provider.  Advantages of cloud computing (storage) can be accessed at any time, from any device, anywhere in the world no need for a customer/client to carry an external storage device provides the user with remote backup of data (data loss/disaster recovery) If a customer/client has a failure of their hard disk or backup device, cloud storage will allow recovery of their data. The cloud system offers almost unlimited storage capacity (at a price!).  Disadvantages of cloud computing (storage) If the customer/client has a slow or unstable internet connection, they could have many problems accessing or downloading their data/files. Costs can be high if a large storage capacity or high download/upload data transfer is required. The potential failure of the cloud storage company is always possible – this poses a risk of loss of all backup data.  Network type Local Area Network (LAN) Wireless Local Area Network (WLAN) Wide Area Network (WAN)  Local area networks (LANs) LAN covers a small area (normally confined to one building or within a close proximity) LAN consists of number of computers and devices that usually connect to a switch which is connected to a router. Advantages:  The sharing of resources  Ease of communication between users.  A network administrator to control and monitor all aspects of the network Disadvantages:  Easier spread of viruses  Slower access to external networks  Increased security risk  Wide area networks (WANs) A WAN is Wide Area Network is a network that extends over a large geographical area (e.g. in a different city or country). A WAN is often created by joining several LANs together. Routers are used to connect LAN networks to form a WAN Network.  Wireless LANs (WLANs) A wireless LAN (WLAN) is a LAN that uses radio signals (WiFi) to connect computers instead of cables. Devices know Access Points (AP) are connected to the wired network at fixed locations. These devices provide the wireless access to devices on the network. It is much more convenient to use wireless connections instead of running long wires all over a building.  Wireless LANs (WLANs) Advantages:  Can access the same services and resources from anywhere within range of the APs  There is no cabling there is a safety improvement and increased flexibility  Adding new computers and devices is very easy and the costs are reduced since extra cabling isn't needed. Disadvantages:  Security can be a big issue.  There may be problems of interference, which can affect the signal.  The data transfer rate is slower than in a wired LAN.  Accessing the Internet Devices Advantages Disadvantages Laptop More portable and smaller in Touch pad may be difficult to size compared to desktop use to navigate webpages. computers. Processors are not as fast as Bigger screens compared to desktop computers. tablets and phones. Desktop Stable internet connection since Has to be connected to a power the connection is normally wired. supply at all times. Use of input devices including Not portable. pointing devices to make navigation easier.  Accessing the Internet Devices Advantages Disadvantages Tablets Tablet: More portable than Signal strength dependant on Smart Phones desktops/laptops however less location. than phones. Smaller display screen. Mobile: Portable: Easy to carry Not all websites designed to be around and use whilst on the used by mobiles/tablets. move. Touch screen may be difficult to Mobile: Always likely to have a use. mobile phone at all times. Limited battery Life. Mobile: Can access internet via phone networks (4G). Network issues and communication  Security issues regarding data transfer Hacking Phishing Pharming Viruses  Passwords Passwords are used in many instances when accessing the internet.  when accessing your email account  when carrying out online banking  accessing social networking sites There are many more instances when you might need to type in a password and, in many cases, a user ID. It is important that passwords are protected.  Passwords Some ways of doing this are described below  Run anti-spyware software to make sure that your passwords are not being relayed back to whoever put the spyware on your computer  Change passwords on a regular basis in case it has come into the possession of another user illegally or accidentally.  Passwords should not be easy to crack (e.g. your favourite colour, name of a pet or favourite rock group)  Passwords are grouped as either strong or weak.  Strong passwords should contain: – at least one capital letter – at least one numerical value – at least one other keyboard character (such as @, *, & etc.). An example of a strong password is: Sy12@#TT90kj=0 An example of a weak password is: GREEN1  Passwords Q. Describe the difference between a weak password and a strong password? A weak password is easy to guess and includes few characters and consists of all letters or all digits. A weak password typically relates to the user for example their favorite color. A strong password is difficult to guess and contains many characters. Also a strong password uses mixture of upper case letters, digits and symbols. Which of the following are weak passwords and which are strong passwords? 1. 25-May-2000 2. Pas5word 3. ChapTer@15 4. AbC*N55! 5. 12345X  Other authentication methods Authentication is used to verify that data comes from a secure and trusted source.  zero login  biometrics  magnetic stripes  smart cards  physical tokens  electronic tokens  Zero login and biometrics Zero login means you do not need to supply your normal login details such as user ID and password to access your device, the internet, your bank details, etc. Zero login essentially relies on devices being smart and secure enough to instantly recognize a user by a number of features based on: » biometrics » behavioural patterns. Biometrics is already used on many smartphones as a way of logging into the phone. » fingerprint » face recognition  Zero login and biometrics Behavioural patterns include: how you walk, your typing speed, your normal location, how you swipe the screen, and so on. The advantages of zero login are :  enhanced security (it is difficult to copy biometrics and behavioural patterns)  an easier  much quicker way to login to a system The disadvantages that need consideration :  How do users know when they are being monitored?  How do you know if and when you have been logged out?  How well protected is it in reality?  Magnetic stripe cards The magnetic stripe cards are used to gain access to the system by swiping the card into the reader Data such as name, ID number, gender, and date of birth may be contained on a magnetic stripe when used as a security device to allow entry to a building, for example. Some ID cards also use a holographic image (hologram). Another form of security is to have a photographic image of the card user printed onto the card surface.  Advantages of Magnetic stripe cards They are easy to use. It is not an expensive technology. Magnetic cards can be remotely deactivated (if lost or stolen). The cards can be multi-purpose (for example, door key cards, network access cards or used in vending machines to buy food or drink).  Disadvantages of Magnetic stripe cards Less secure than, for example, biometric methods (no encryption is used and the stripe contents can be copied fairly easily). The cards wear out with a lot of use. Magnetic readers often fail to read the cards on first attempt.  Smart cards By inserting a tag (chip and antenna) into a security card, it can act as a smart contactless card (that is, it can be read from a distance and does not have to be swiped through a card reader). The chip on the smart card can store data such as name, security number, gender, date of birth and a PIN. Smart cards can be used as a security device. If the card is in a wallet or a pocket as the owner of the card walks up to a security gate, readers on either side of the gate quickly scan the security data stored on the RFID tag embedded in the card. The user will then be invited to enter a PIN on the keypad. If all details match, then access will be allowed.  Physical tokens A physical (or hardware) token is a form of authentication in the form of a physical, solid object. The user’s interaction with a login system is used to prove that the user has possession of the token. Physical tokens contain internal clocks and when a PIN and other authentication details are entered, then a one-time password (OTP) is generated. The OTP is shown on a small screen. The code changes on a regular basis and is usually only valid for less than a minute.  Physical tokens There are two types of physical tokens: a disconnected physical token – a separate device is used, requiring the user to key in data manually using a keypad a connected physical token – this type of token transmits the generated one-time password directly to a computer through a USB connection; the user does not need to manually enter data  Electronic tokens Electronic (software) tokens are software installed on a user’s device, such as a smartphone. The app generates a one-time password (OTP) which is valid for less than a minute. The user enters this OTP when prompted by the website, together with some other form of authentication, such as PIN, touch ID or face ID. The website server runs the same software as the app. Because both the server and smartphone have synchronised clocks, they will generate the same numbers. Once the OTP and other form of authentication are verified by the website, the user will be allowed access.  Anti-malware software Anti-malware software, known as anti-virus software, to protect devices against a potential virus attack. Running anti-virus software in the background on a computer will constantly check for virus attacks. Although various types of anti-virus software work in different ways they all have the following common features:  They check software or files before they are run or loaded on a computer.  Anti-virus software compares a possible virus against a database of known viruses.  They carry out heuristic checking – this is the checking of software for types of behaviour that could indicate a possible virus; this is useful if software is infected by a virus not yet on the database.  Anti-malware software  Any possible files or programs which are infected are put into quarantine which: – allows the virus to be automatically deleted, or – allows the user to make the decision about deletion  Anti-virus software needs to be kept up to date because new viruses are constantly being discovered.  Full system checks need to be carried out once a week, for example, because some viruses lie dormant and would only be picked up by this full system scan.  Data protection acts Data protection Act applies to paper based or electronic forms of data stored on a computer. The data protection act is to protect rights of the individual who the data is obtained from.  Principles of the Data Protection Act 1. Data must be fairly and lawfully processed. 2. Data can only be processed for the stated purpose. 3. Data must be adequate, relevant and not excessive. 4. Data must be accurate. 5. Data must not be kept longer than necessary. 6. Data must be processed in accordance with the data subject rights. 7. Data must be kept secure. 8. Data must not be transferred to another country unless they have adequate protection.  Network communication  Physical Fax Machines Requires a fax machine and a telephone line. Number of the recipient dialed before the document is copied and sent. Physical documents are printed and can be signed. Disadvantage Anyone can access faxed documents. The fax may be out of paper or ink (toner). No notification of fax received.  Network communication  Electronic Faxing Electronic Fax is sent via a internet connection. No need to buy a fax machine, ink or paper. Electronic Fax documents are sent to an email which will ensure the correct person will receive the fax – less chance of document being intercepted. Electronic Fax's can also be sent directly to a fax machine. Send fax's from any location with an internet connection. No additional cost to send fax over internet network.  Network communication  Email Communication Can send multiple attachments. Can send to multiple recipients in one message. Emails can be received instantly and accessed on many platforms including tablets and phones. Disadvantage Email attachments may include viruses. May receive spam (unwanted mail). May receive phishing (scam) emails to obtain personal data.  Electronic conferencing Three types of electronic conferencing: » video conferencing » audio conferencing » web conferencing  Video conferencing Video conferencing is a communication method that uses both video and sound using an internet connection. It is a substitute for face-to-face conferences between a number of people, who may be in a different part of the country or live overseas. It is carried out in real time and makes use of some form of network. The basic hardware includes: » webcams » large monitors/television screens » microphones » speakers.  Video conferencing Software used in video conferencing: » Webcam and microphone software drivers » CODEC (CODER-DECODER OR COMPRESSION-DECOMPRESSION) » Echo cancellation software  Video conferencing Advantages No need to travel to have meetings which would cut down on travelling costs (including flights and hotel) and travelling time. Video conference can be held at short notice. Facilitates long distance learning – students can access live lectures without travelling.  Video conferencing Disadvantages Technical problems with the internet or hardware could effect the quality of the video conference. Set up costs to purchase hardware/software and to provide relevant training to staff. Lack of personal contact you would have if it was a face to face meeting. Different time zones could make it difficult to find a suitable time to have a meeting. Not possible to sign documents.  Audio conferencing Audio conference can be done over the telephone network or using a computer making use of VOIP. The basic hardware includes: » Telephone » microphones » speakers.  Audio conferencing 1. The organizer of the phone conference is given a unique Pin which can be shared participants. 2. For Participants to join they have to dial the conference phone number. 3. Then they would have to enter a PIN.  Web conferencing Web conference can be done using internet connection. It is very similar to video conference as participants can hear audio and see a live video stream. Participants can join the web conference by clicking on the supplied link from the organizer. Participants can join and leave the web conference at any time. Instant messaging (IM) feature is available to communicate with other participants. Participants can be given permission to speak and can share content such as images, video or presentations.