lecture 3 computer networks and malware.pdf

CSM 184 Computer Networks, Malware and Current trends in Computing 1  Computer Networks A network is basically a combination of hardware and software that send data from one computer to another. It can also be defined as two or more computers th...

CSM 184 Computer Networks, Malware and Current trends in Computing 1  Computer Networks A network is basically a combination of hardware and software that send data from one computer to another. It can also be defined as two or more computers that are connected to each other to share and exchange data. The hardware consist of the physical components that carries data or signals from one point to the other while the software are the instructions that make the services expected from a network possible. 2  Applications of Computer Networks Sharing of resources such as printers Sharing of expensive software's and database Communication from one computer to another computer Exchange of data and information among users via network Sharing of information over geographically wide areas. 3  Benefits of Computer Networks Increased speed Reduced cost Improved security Centralized software managements Electronic mail Flexible access 4  Disadvantages of Computer Networks High cost of installation Requires time for administration Failure of server Cable faults 5  Computer Networks A computer network must meet a number of criteria, notable among these are performance, security and reliability. Performance is normally measured in terms of transit time and response time. The performance of a network can be affected by the number of people on the network at a time, the transmission medium, What else? 6  Computer Networks Security basically deals with preventing unauthorized users to access, update or damage data. It also deals with the policies needed for implementation and procedures needed for recovery from breaches and data loses. Reliability is usually measured by the frequency at which failure occurs, the time it takes the network to recover from a failure and the network‘s robustness in an emergency or disaster. 7  Types of Computer Networks As mentioned earlier, a network consists of two or more devices that have been connected through links to send and receive data. A link is simply a communication pathway for transferring data from one device to another. There are basically two types of connections namely point-to-point and multipoint connections. 8  Types of Computer Networks For a point-to-point connection, there is a dedicated link between two devices and the entire capacity of the link is set aside for transmission between these two devices. A multipoint connection on the other hand is one in which more than two devices share a common link. 9  Network Topology A network topology refers to the way in which the network devices are connected to each other. When two or more devices are connected they form a link, and one or more links form a topology. In a network the devices are normally referred to as nodes. There are basically four main types of network topologies and these are the mesh, star, bus and ring. 10  Mesh Topology In a mesh topology each device has a dedicated point- to-point link to all other devices in the network. In other words, there is a direct connection between every two devices on the network. A typical mesh topology is as shown below: 11 Mesh Topology 12  Star Topology In a star topology, each device has a dedicated point-to- point link only to a central controller ( e.g hub, switch) In other words, there is no direct link between any two devices. A typical star topology is as shown below: 13 Star Topology 14  Bus Topology In a bus topology one long cable called the bus cable is used to link all the devices in a link. The bus topology is a multipoint. Each device is connected to the bus cable by drop lines and connectors (taps) 15 Bus Topology 16 D E P A R T M E N T O F C O M P U T E R S C I E N C E , K N U S T - K U M A S I  RING TOPOLOGY  Ring topology is a type of network topology in which each device is connected to two other devices on either side via an RJ-45 cable or coaxial cable.  This forms a circular ring of connected devices which gives it its name.  Data is commonly transferred in one direction along the ring, known as a unidirectional ring.  This reduces the chances of collisions and increases the overall speed of data transmission. D E P A R T M E N T O F C O M P U T E R S C I E N C E , K N U S T - K U M A S I D E P A R T M E N T O F C O M P U T E R S C I E N C E , K N U S T - K U M A S I Classification of Networks by their Geography NETWORKS PAN LAN WAN MAN CAN Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 21  Local Area Network (LAN) LAN is a network which is designed to operate over a small physical area such as an office, factory or a group of buildings. LANs are easy to design and troubleshoot Exchange of information and sharing of resources becomes easy because of LAN. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 22  Local Area Network (LAN) In LAN all machines are connected to a single cable or sometimes wireless. Different types of topologies such as star, tree, bus, ring, etc can be used  It is usually a privately owned network. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 23  Wide Area Network (WAN) When network spans over a large distance or when the computers to be connected to each other are at widely separated locations a local area network cannot be used. A wide area network(WAN) is installed. The communication between different users of WAN is established using leased telephone lines, satellite links and similar channels. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 24  Wide Area Network (WAN) It is cheaper and more efficient to use the phone network for the link. Most WAN networks are used to transfer large blocks of data between its users. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 25  Personal Area network (PAN) A personal area network is a computer network organized around an individual person. It generally consists of a mobile computer, a cell phone or personal digital assistant. PAN enables the communication among these devices. It can also be used for communication among personal devices themselves for connecting to a digital level network and internet. The PANs can be constructed using wireless or cables. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 26  Campus Area Network (CAN) The campus area network is made up of an interconnection of LAN with limited geographical area. Network equipment such as switches, routers and the transmission media i.e. optical fibre etc are almost entirely owned by the campus owner. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 27  Metropolitan Area Network (MAN) It is in between LAN & WAN technology that covers the entire city. It uses similar technology as LAN. It can be a single network such as cable TV network, or a measure of connecting a number of LAN’s on a large network so that resources can be shared LAN to LAN as well as device to device. Reference: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 28 D E P A R T M E N T O F C O M P U T E R S C I E N C E , K N U S T - K U M A S I Figure taken from: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK Distinguish Between LAN, MAN AND WAN Figure taken from: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 30 Distinguish Between LAN, MAN AND WAN Figure taken from: CN1047 INTRODUCTION TO COMPUTER NETWORKINGCHAPTER 1BASIC CONCEPTS OF NETWORK 31  Malicious software Malware, or malicious software, is a term for any kind of computer software with malicious intent. Most online threats are some form of malware. Malware includes any intrusive software developed by cybercriminals (often called hackers) to steal data and damage or destroy computers and computer systems Malware can take many forms, including viruses, worms, trojan horses, ransomware, and spyware. Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 32  Viruses A computer virus is type of malicious software, or malware, that spreads between computers and causes damage to data and software. Computer viruses aim to disrupt systems, cause major operational issues, and result in data loss and leakage. It requires some form of user’s interaction to infect the user’s device. Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 33  Viruses The classic example is an e-mail attachment containing malicious executable code.  If a user receives and opens such an attachment, the user inadvertently runs the malware on the device. Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 34  Worms A WORM is a malware which can enter a device without any explicit user interaction. Its primary function is to self-replicate and infect other computers while remaining active on infected systems For example, a user may be running a vulnerable network application to which an attacker can send malware. In some cases, without any user intervention, the application may accept the malware from the Internet and run it, creating a worm. Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 35  Trojan Horses A trojan horse is a type of malware that disguises itself within legitimate applications and software. A trojan usually purports to perform some obvious function, yet upon execution, it compromises the user’s security. They are camouflaged in the form of regular software, such as utilities, games and sometimes even antivirus programs. Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 36  Phishing Phishing – The fraudulent practice of sending emails purporting to be from reputable companies in order to induce individuals to reveal personal information, such as passwords and credit card numbers. It often involves pretending to be a trusted entity and creating a sense of urgency, like threatening to close or seize a victim's bank or insurance account. An alternative technique to impersonation-based phishing is the use of fake news articles to trick victims Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 37  Spam Spam is any kind of unwanted, unsolicited digital communication that gets sent out in bulk. Spam usually includes unsolicited email which sends to the users without their request or interest and usually contains phishing links which directs users to vulnerable sites. Often spam is sent via email, but it can also be distributed via text messages, phone calls, or social media. Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 38  Adware Adware is a category of software applications that display advertisements on computers or alter search results in browsers. Some adware is purely malicious and does not ask for user consent. Others, on the other hand, notify you of their installation through confusing user agreements or installation options enabled by default. When infested by an adware, it usually slows your browser and installs pop-ups that it creates. It also consumes your data and bandwidth thus affecting your working abilities Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 39 Ransomware Ransomware is malware that employs encryption to hold a victim’s information at ransom. A user or organization’s critical data is encrypted so that they cannot access files, databases, or applications. A ransom is then demanded to provide access. Ransomware is often designed to spread across a network and target database and file servers, and can thus quickly paralyze an entire organization Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 40 Reference: F-Secure - https://www.f-secure.com/en/articles/what-is-malware 41 Symptoms of Malware attacks Reference: SECTIGO https://sectigo.com/resource-library/what-are-the-signs-you-have-malware 42 Symptoms of Malware attacks Reference: HowToRemove Guide - https://howtoremove.guide/clear-signs-malware-infection/ 43  Protecting computers from malware attacks Install Firewalls and Antivirus Software Only Use Trusted Antivirus and Malware Software Configure Regular Scans and Monitor Settings Always Update Your Operating System Rely Only On Secure Networks (Encrypted) Reference: What Is My IP - https://whatismyipaddress.com/protection-from-malware 44  Protecting computers from malware attacks Employ Browser Common Sense Keep a Tight Grip on Your Personal Information Stay Up-to-Date on the Latest Attacks Use complex and secured passwords Reference: What Is My IP - https://whatismyipaddress.com/protection-from-malware 45