Cyber Security Module 1 Part 1 PDF

Module 1: Introduction to Cyber Security By Jyothis K.P. Assistant Professor Department of Computer Science & Engineering Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖...

Module 1: Introduction to Cyber Security By Jyothis K.P. Assistant Professor Department of Computer Science & Engineering Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖Network Devices ❖Network Media ❖Types of Network ❖Network Topology ❖Layered communication Dayananda Sagar Academy of Technology & Management The Computer Network A computer network is a group of computers/devices(Nodes) that use a set of common communication protocols over digital interconnections for the purpose of sharing resources located on or provided by the network nodes. The nodes of a computer network may include personal computers, servers, networking hardware, or other specialised or general-purpose hosts. The interconnections between nodes are formed from a broad spectrum of telecommunication network technologies, based on physically wired, optical, and wireless technologies. A communication protocol is a set of rules for exchanging information over a network. physically wired, optical, and wireless Dayananda Sagar Academy of Technology & Management The Network Diagram Wired Network PC Firewall The Internet Fiber Optic Network Cable Router Switch Server Other LANS Wireless Network Dayananda Sagar Academy of Technology & Management The Advantages/Uses of Network Simultaneous Access There are moments in any business when several workers may need to use the same data at the same time. Shared Peripheral Devices Personal Communications Videoconferencing Voice over Internet Protocol (VoIP):-VoIP transmits the sound of voice over a computer network using the Internet Protocol (IP ) rather than sending the signal over traditional phone wires Easier Data Backup Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖Network Devices ❖Network Media ❖Types of Network ❖Network Topology ❖Layered communication Dayananda Sagar Academy of Technology & Management The Networking Devices(Nodes) 1. NIC Card 2. Repeater 3. Hub 4. Switch 5. Bridge 6. Router 7. Gateway 8. Firewall Dayananda Sagar Academy of Technology & Management 1. Network Interface Card NIC is used to physically connect host devices to the network media. A NIC is a printed circuit board that fits into the expansion slot of a bus on a computer motherboard. It can also be a peripheral device. NICs are sometimes called network adapters. Each NIC is identified by a unique code called a Media Access Control (MAC) address. This address is used to control data communication for the host on the network. Dayananda Sagar Academy of Technology & Management 2. Repeaters A repeater is a network device used to regenerate a signal. Repeaters regenerate analog or digital signals that are distorted by transmission loss due to attenuation. A repeater does not make an intelligent decision concerning forwarding packets Dayananda Sagar Academy of Technology & Management 3. Hubs Hubs concentrate on connections. In other words, they take a group of hosts and allow the network to see them as a single unit. This is done passively, without any other effect on the data transmission. Active hubs concentrate hosts and also regenerate signals. Dayananda Sagar Academy of Technology & Management 4. Bridges Bridges convert network data formats and perform basic data transmission management. Bridges provide connections between LANs. They also check data to determine if it should cross the bridge. This makes each part of the network more efficient Dayananda Sagar Academy of Technology & Management 5. Switches Switches add more intelligence to data transfer management. They can determine if data should remain on a LAN and transfer data only to the connection that needs it. Another difference between a bridge and switch is that a switch does not convert data transmission formats Dayananda Sagar Academy of Technology & Management 6. Routers Routers have all the capabilities listed above. Routers can regenerate signals, concentrate multiple connections, convert data transmission formats, and manage data transfers. They can also connect to a WAN, which allows them to connect LANs that are separated by great distances. Dayananda Sagar Academy of Technology & Management 7. Gateway A gateway is a piece of networking hardware used in telecommunications for telecommunications networks that allows data to flow from one discrete network to another. Gateways are distinct from routers or switches in that they communicate using more than one protocol to connect a bunch of networks Dayananda Sagar Academy of Technology & Management 8. Firewall A firewall is a network device or software for controlling network security and access rules. Firewalls are inserted in connections between secure internal networks and potentially insecure external networks such as the Internet. Firewalls are typically configured to reject access requests from unrecognized sources while allowing actions from recognized ones. The vital role firewalls play in network security grows in parallel with the constant increase in cyber attacks. Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖Network Devices ❖Network Media ❖Types of Network ❖Network Topology ❖Layered communication Dayananda Sagar Academy of Technology & Management Network Media The function of the media is to carry a flow of information through a LAN. A. Wired Media:- A widely adopted family that uses copper and fiber media in local area network (LAN) technology are collectively known as Ethernet 1. Copper Cable a. Coaxial Cables b. Shielded Twisted Pair(STP) c. Unshielded Twisted Pair 2. Fibre Optic Cable B. Wireless Media:- use the atmosphere, or space, as the medium. Dayananda Sagar Academy of Technology & Management 1. Copper Cable The most common, easiest, quickest, and cheapest form of network media to install. The disadvantage of sending data over copper wire is that the further the signal travels, the weaker it becomes. Dayananda Sagar Academy of Technology & Management a. Coaxial Cable It can be run longer distances than Twisted pair Cables. Speed: 10-100Mbps Cost: Inexpensive Media and connector size: Medium Maximum cable length: 500m Dayananda Sagar Academy of Technology & Management b. Shielded Twisted Pair(STP) Speed: 0-100Mbps Cost: Moderate Media and connector size: Medium to large Maximum cable length: 100m Dayananda Sagar Academy of Technology & Management c. Unshielded Twisted Pair UTP is a four-pair wire medium Speed: 10-100-1000 Mbps* used in a variety of networks. Cost: Least Expensive Each of the eight copper wires Media and connector size: Small in the UTP cable is covered by Maximum cable length: 100m * (Depending insulating material on the quality/category of cable) Dayananda Sagar Academy of Technology & Management UTP Implementation EIA/TIA specifies an RJ-45 connector for UTP cable. The letters RJ stand for registered jack. Dayananda Sagar Academy of Technology & Management Fiber Optic Cable Glass fiber carrying light pulses, each pulse a bit. Based on the Total Internal Reflection of Light. High-speed point-to-point transmission 10-100’s Gbps low error rate: repeaters spaced far apart immune to electromagnetic noise Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖Network Devices ❖Network Media ❖Types of Network ❖Network Topology ❖Layered communication Dayananda Sagar Academy of Technology & Management Types of Networks 1. Personal Area Network (PAN) 2. Local Area Network (LAN) 3. Campus Area Network (CAN) 4. Metropolitan Area Network (MAN) 5. Wide Area Network (WAN) 6. Storage-Area Network (SAN) 7. Virtual Private Network (VPN) 8. Client Server Network 9. Peer to Peer Network (P2P) Dayananda Sagar Academy of Technology & Management 1. Personal Area Network 1. Personal Area Network (PAN) is a computer network used for data transmission amongst devices such as computers, telephones, tablets and personal digital assistants. 2. Also Known as HAN (Home Area Network) 3. PANs can be used for communication amongst the personal devices themselves (interpersonal communication), or for connecting to a higher level network and the Internet (an uplink) where one "master" device takes up the role as internet router. Dayananda Sagar Academy of Technology & Management 2. Local Area Network Xerox Corporation worked in collaboration with DEC and Intel to create Ethernet, which is the most pervasive LAN architecture used today. Ethernet has evolved and has seen significant improvements in regard to speed and efficiency. An upside of a LAN is fast data transfer with data speed that can reach up to 10Gbps. Other significant LAN technologies are Fiber Distributed Data Interface (FDDI) and token ring. Dayananda Sagar Academy of Technology & Management 3. Campus Area Network Larger than LANs, but smaller than metropolitan area networks these types of networks are typically seen in universities, large K-12 school districts or small businesses. They can be spread across several buildings that are fairly close to each other so users can share resources Dayananda Sagar Academy of Technology & Management  4. Metropolitan Area Network 1. A MAN is larger than a LAN but smaller than or equal in size to a WAN. 2. The size range anywhere from 5 to 50km in diameter. 3. MANs are typically owned and managed by a single entity. 4. This could be an ISP or telecommunications company that sells its services to end-users in that metropolitan area. 5. For all intents and purposes, a MAN has the same characteristics as a WAN with distance constraints. Dayananda Sagar Academy of Technology & Management  5. Wide Area Network A Wide Area Network exist over a large area Data travels through telephone or cable lines Usually requires a Modem The world’s largest Wide Area Network in the Internet Dayananda Sagar Academy of Technology & Management  6. Storage Area Network SAN may be referred to as a Sub network or special purpose network. Its special purpose is to allow users on a larger network to connect various data storage devices with clusters of data servers. SANs can be accessed in the same fashion as a drive attached to a server. Dayananda Sagar Academy of Technology & Management  7. Virtual Private Network VPN is a private network that can access public networks remotely. VPN uses encryption and security protocols to retain privacy while it accesses outside resources. When employed on a network, VPN enables an end user to create a virtual tunnel to a remote location. Typically, telecommuters use VPN to log in to their company networks from home. Authentication is provided to validate the identities of the two peers. Confidentiality provides encryption of the data to keep it private from prying eyes. Integrity is used to ensure that the data sent between the two devices or sites has not been tampered with. Dayananda Sagar Academy of Technology & Management  8. Client/Server Network In a client/server arrangement, network services are located on a dedicated computer called a server. The server responds to the requests of clients. The server is a central computer that is continuously available to respond to requests from clients for file, print, application, and other services. Most network operating systems adopt the form of a client/server relationship. Typically, desktop computers function as clients, and one or more computers with additional processing power, memory, and specialized software function as servers. Dayananda Sagar Academy of Technology & Management  9. Peer to Peer Network Usually very small networks Each workstation has equivalent capabilities and responsibilities Does not require a switch or a hub. These types of networks do not perform well under heavy data loads. Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖Network Devices ❖Network Media ❖Types of Network ❖Network Topology ❖Layered communication Dayananda Sagar Academy of Technology & Management  Network Topologies Network topology defines the structure of the network. A. Physical topology:- It define the actual layout of the wire or media. 1. Bus 2. Ring 3. Star 4. Tree(Hierarchical) 5. Mesh B. Logical topology:- It defines how the hosts access the media to send data. 1. Broadcast 2. Token passing D. Hybrid Topology Dayananda Sagar Academy of Technology & Management  1. Bus Topology All devices are connected to a central cable, called bus or backbone. T T There are terminators at each end of the bus that stops the signal and keeps it from traveling backwards. Advantages: Disadvantages: 1. There is no central controller. 1. It is possible that more than one station may 2. Control resides in each station attempt transmission simultaneously (collision or contention). 3. The less interconnecting wire is required. 2. Difficult reconfiguration and fault isolation. 4. Ease of installation. 3. A fault or break in the bus cable stops all transmission, even between devices on the same 5. Backbone cable can be laid along the side of the problem. most efficient path, and then connected to the nodes by drop lines 4. The damaged area reflects signals in the direction of various lengths of origin, creating noise in both directions Dayananda Sagar Academy of Technology & Management  2. Ring Topology All devices are connected to one another in the shape of a closed loop. Each device is connected directly to two other devices, one on either side of it. Advantages: 1. Avoids the collisions that are possible in the bus topology. 2. Each pair of stations has a point-to-point connection. 3. A signal is passed along the ring in one direction, from device to another, until it reaches its destination. 4. Each device incorporates a repeater. 5. Relatively easy to install and reconfigure. 6. Fault isolation is simplified. Disadvantages: 1. A break in the ring (such as station disabled) can disable the entire network. 2. Unidirectional traffic. Dayananda Sagar Academy of Technology & Management  3. Star Topology All devices are connected to a central hub. Nodes communicate across the network by passing data through the hub or switch. Advantages: 1. Easy to install and reconfigure. 2. Robustness, if one link fails; only that link is affected. All other links remain active. 3. Easy fault identification and isolation. As long as the hub is working, it can be used to monitor link problems and bypass defective links. Disadvantages: 1. The devices are not linked to each other. 2. If one device wants to send data to another, it sends it to the controller, which then relays the data to the other connected device. Dayananda Sagar Academy of Technology & Management  4. Tree/Hierarchical Topology Advantages: 1. It allows more devices to be attached to a single central hub and can therefore increase the distance a signal can travel between devices. 2. It allows the network to isolate and prioritize communications from different computers. Disadvantages: 1. The devices are not linked to each other. 2. If one device wants to send data to another, it sends it to the controller, which then relays the data to the other connected device. 3. The addition of secondary hubs brings two further advantages. Dayananda Sagar Academy of Technology & Management  6. Mesh Topology Each host has its connections to all other hosts. Mesh topology is implemented to provide as much protection as possible from interruption of service. 1. A nuclear power plant might use a mesh topology in the networked control systems. 2. Although the Internet has multiple paths to any one location, it does not adopt the full mesh topology. Advantages: Disadvantages: 1. The use of dedicated links guarantees that each 1. A large amount of cabling required. connection can carry its data load, thus eliminating 2. A large amount of I/O ports required. the traffic problems that can occur when links must 3. Installation and reconfiguration are be shared by multiple devices. difficult. 2. It is robust, if one link becomes unusable, it does 4. The sheer bulk of the wiring can be not incapacitate (affect) the entire system. greater than the available space (in the 3. Privacy and Security (every message sent travels walls, ceiling, or floors) can accommodate. along a dedicated line; only the intended recipient 5. The hardware required to connect each sees it). link (I/O ports and cables) can be 4. Point-to-point links make fault identification and prohibitively expensive. fault isolation easy. Dayananda Sagar Academy of Technology & Management  Wireless Networks Wireless network is a type of computer network that uses wireless data connections for connecting network nodes. Example Bluetooth Wi-Fi Dayananda Sagar Academy of Technology & Management  Bluetooth Bluetooth is a short-range wireless technology standard used for exchanging data between fixed and mobile devices over short distances. It is using UHF radio waves in the ISM bands, from 2.402 GHz to 2.48 GHz. The IEEE standardized Bluetooth as IEEE 802.15.1, but no longer maintains the standard. Dayananda Sagar Academy of Technology & Management  Wi-Fi Wi-Fi Stands for Wireless Fidelity. Wi-Fi, is a Local Area Wireless technology. Wi-Fi networks use radio technologies to transmit and receive data at high speed. It is based on the IEEE 802.11 family of standards. Access point: The access point is a wireless LAN transceiver or “ base station” that can connect one or many wireless devices simultaneously to the internet Dayananda Sagar Academy of Technology & Management Course Content ❖Introduction to Computer Network ❖Network Devices ❖Network Media ❖Types of Network ❖Network Topology ❖Layered communication Dayananda Sagar Academy of Technology & Management Layered communication Dayananda Sagar Academy of Technology & Management THE OSI MODEL ▶ The International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards ▶ The Open Systems Interconnection (OSI) model. ▶ It was first introduced in the late 1980s. Dayananda Sagar Academy of Technology & Management Seven layers of the OSI model Dayananda Sagar Academy of Technology & Management Open Systems Interconnection (OSI) model ▶ The OSI model is not a protocol; it is a model for understanding and designing a network architecture that is flexible, robust, and interoperable Dayananda Sagar Academy of Technology & Management Various mnemonics ❖ Make it easier to remember the order of the OSI model’s layers Dayananda Sagar Academy of Technology & Management Protocol Data Units (PDUs) ▶ OSI model, each layer adds a header containing protocol information specific to that layer. ▶ These headers are called Protocol Data Units (PDUs), and the process of adding these headers is called encapsulation. Dayananda Sagar Academy of Technology & Management  Physical layer ▶ The Physical layer (Layer-1) controls the signalling and transferring of raw bits onto the physical medium ▶ The Physical layer provides specifications for a variety of hardware: Cabling Connectors and transceivers Network interface cards (NICs) Wireless radios Hubs Dayananda Sagar Academy of Technology & Management  Protocol Data Units (PDUs) = Bits ▶ The physical layer coordinates the functions required to carry a bit stream over a physical medium. Dayananda Sagar Academy of Technology & Management  Physical characteristics ▶ Representation of bits (Os and I s). ▶ Data rate. ▶ Physical topology. ▶ Transmission mode. Dayananda Sagar Academy of Technology & Management  Data Link Layer ▶ The Data-link layer packages the higher-layer data into frames, ▶ The data-link frame contains the source and destination hardware (or physical) address ▶ The most common hardware address is the Ethernet MAC address. Dayananda Sagar Academy of Technology & Management  Protocol Data Units (PDUs) = Frames ▶ Physical addressing. If frames are to be distributed to different systems on the network, ▶ The data link layer adds a header to the frame to define the sender and/or receiver of the frame Dayananda Sagar Academy of Technology & Management  Network Layer ▶ The network layer is responsible for the source-to-destination delivery of a packet, possibly across multiple networks (links). ▶ The network layer ensures that each packet gets from its point of origin to its final destination Dayananda Sagar Academy of Technology & Management ▶ Protocol Data Units (PDUs) = Packets ▶ Responsibilities of the network layer :- ▶ Logical addressing ▶ Routing. Dayananda Sagar Academy of Technology & Management A packet can have multiple headers. ▶ The IP header has information such as IP addresses for the source and destination, ▶ what protocol the packet ▶ TCP header has information such as port number ▶ Ethernet header has information such as the MAC address for the source and destination Dayananda Sagar Academy of Technology & Management  The Transport Layer ▶ Transport layer communication falls under two categories: Connection-oriented – requires that a connection with specific agreed-upon parameters be established before data is sent. Connectionless – requires no connection before data is sent. Dayananda Sagar Academy of Technology & Management ▶ The TCP/IP protocol suite incorporates two Transport layer protocols: Transmission Control Protocol (TCP) – connection-oriented User Datagram Protocol (UDP) - connectionless Dayananda Sagar Academy of Technology & Management Dayananda Sagar Academy of Technology & Management 6 TCP flags: Dayananda Sagar Academy of Technology & Management Dayananda Sagar Academy of Technology & Management ▶ Responsibilities of the transport layer ▶Service-point addressing ▶ Connection control ▶ Flow control. Dayananda Sagar Academy of Technology & Management Example ▶ For example, a Transport layer protocol such as TCP will add a header containing flow control, port numbers, and sequencing. ▶ The Network layer header contains logical addressing information, ▶ The Data-link header contains physical addressing and other hardware specific information Dayananda Sagar Academy of Technology & Management Session Layer ▶ The services provided by the first three layers (physical, data link, and network) are not sufficient for some processes. ▶ The Session layer (Layer-5) is responsible for establishing, maintaining, and ultimately terminating sessions between devices ▶ If a session is broken, this layer can attempt to recover the session. Dayananda Sagar Academy of Technology & Management Responsibilities of Session Layer ▶ Dialog control : - The session layer allows two systems to enter into a dialog. It allows the communication between two processes ▶ Synchronization:- The session layer allows a process to add checkpoints, or synchronization points, to a stream of data. ▶ Example, if a system is sending a file of 2000 pages, it is advisable to insert checkpoints after every 100 pages to ensure that each 100- page unit is received and acknowledged independently Dayananda Sagar Academy of Technology & Management  Presentation Layer ▶ The presentation layer is concerned with the syntax and semantics of the information exchanged between two systems. ▶ This ensures that data from the sending application can be understood by the receiving application Dayananda Sagar Academy of Technology & Management Responsibilitie s ▶ Translation :- The processes in two systems are usually exchanging information in the form of character strings, numbers, and so on. Their must be change of bit streams before being transmitted (encoding) ▶ Encryption :- To carry sensitive information, a system must be able to ensure privacy. ▶ Compression :-Data compression reduces the number of bits contained in the information. such as text, audio, and video Dayananda Sagar Academy of Technology & Management ▶ Presentation layer formats include ▶Text - RTF, ASCII, EBCDIC ▶ Images - GIF, JPG, TIF ▶ Audio - MIDI, MP3, WAV ▶Movies - MPEG, AVI, MOV Dayananda Sagar Academy of Technology & Management  Application Layer ▶ The application layer enables the user, whether human or software, to access the network. ▶ It provides user interfaces and support for services such as electronic mail, remote file access and transfer, shared database management, and other types of distributed information services. Dayananda Sagar Academy of Technology & Management ▶ Examples of Application layer protocols include: ▶ FTP, via an FTP client ▶ HTTP, via a web browser ▶ POP3 and SMTP, via an email client ▶ Telnet ▶ Responsibilities :- ▶ File transfer, access, and management ▶ Mail services – (e-mail Storage) ▶ Directory Services :- Distributed Data Base Sources and Access for Global information. Dayananda Sagar Academy of Technology & Management Summary of layers Dayananda Sagar Academy of Technology & Management Dayananda Sagar Academy of Technology & Management TCP/IP PROTOCOL SUITE ▶ The DoD (Department of Defense) developed their own networking model, which became known as the DoD or TCP/IP Model. Dayananda Sagar Academy of Technology & Management Layers Dayananda Sagar Academy of Technology & Management Dayananda Sagar Academy of Technology & Management Internet Protocol address (IP address) ▶ An Internet Protocol address (IP address) is a unique number assigned to each computer or device (such as printer) so that each of them can be uniquely identified on the network ▶ Internet Protocol Versions ▶ Two version of Internet Protocol (IP): IPv4 and a new version called IPv6 IPv4 was the first version of IP. It was deployed for production in the ARPANET in 1983. Today it is most widely used IP version IPv4 uses a 32-bit address (4 billion addresses) IPv6 is the most recent version of the Internet Protocol. IPv6 Uses a 128-bit address Dayananda Sagar Academy of Technology & Management Range of IPv4 Dayananda Sagar Academy of Technology & Management Dayananda Sagar Academy of Technology & Management  Types of IP Address ▶ Private IP Address: A private IP address is the one that is assigned to a computer on the Local Area Network (LAN). ❖ Example : 192.168.0.2 ▶ Public IP Address: A public IP address is the one that is assigned to a computer connected to the Internet. ❖ Example : 59.93.115.125 Dayananda Sagar Academy of Technology & Management IPv6 ▶ An IPv6 address is a 128-bit alphanumeric string that identifies an endpoint device in the Internet Protocol Version 6 (IPv6) addressing scheme. ▶ IPv6 address is 128 bits long and is arranged in eight groups ▶ Example : FE80:CD00:0000:0CDE:1257:0000:211E:729C Dayananda Sagar Academy of Technology & Management NETWORK PORT ▶ A computer may be running several services on it like HTTP (web server), SMTP, FTP and so on ▶ Each of these services are uniquely identified by a number called network port ▶ The range for port numbers is 0 – 65535, for both TCP and UDP ❖ Example : 192.168.60.125:443 ▶ The first 1024 ports (0-1023) have been reserved for widely-used services, and are recognized as well-known ports Dayananda Sagar Academy of Technology & Management Protocols/Services ▶ Hyper Text Transfer Protocol (HTTP) ▶ Example: http://www.example.com ▶ File Transfer Protocol (FTP) ▶ Example: ftp://www.example.com ▶ Simple Main Transfer Protocol (SMTP) ▶ The Simple Mail Transfer Protocol provides a standard for sending e-mails from one server to another. ▶ Telnet : is a network protocol that allows you to connect to remote hosts on the Internet or on a local network. ▶ Example :telnet 127.0.0.1 25 ▶ SSH (Secure Shell) Dayananda Sagar Academy of Technology & Management Well Known Port Numbers Dayananda Sagar Academy of Technology & Management Dayananda Sagar Academy of Technology & Management