COMPUTER NETWORK AND SECURITY (According to IOE syllabus) PREPARED BY: ER.ANKU JAISWAL LECTURER PULCHOWK CAMPUS, IOE BY: ER. ANKU JAISWAL SYLLABUS 1. Introduction to Computer Network (5 hours) 1.1 Uses of Computer Network 1.2 Networking model client/server, p2p, active network 1.3 Protocols and Standards 1.4 OSI model and TCP/IP model 1.5 Comparison of OSI and TCP/IP model 1.6 Example network: The Internet, X.25, Frame Relay, Ethernet, VoIP, NGN and MPLS, xDSL. 2. Physical Layer (5 hours) 2.1 Network monitoring: delay, latency, throughput 2.2 Transmission media: Twisted pair, Coaxial, Fiber optic, Line-of-site, Satellite 2.3 Multiplexing, Circuit switching, Packet switching, VC Switching, Telecommunication switching system (Networking of Telephone exchanges) 2.4 ISDN: Architecture, Interface, and Signaling 3. Data Link Layer (5 hours) 3.1 Functions of Data link layer 3.2 Framing 3.3 Error Detection and Corrections, 3.4 Flow Control 3.5 Examples of Data Link Protocol, HDLC, PPP 3.6 The Medium Access Sub-layer 3.7 The channel allocation problem 3.8 Multiple Access Protocols 3.9 Ethernet, 3.10 Networks: FDDI, ALOHA, VLAN, CSMA/CD, IEEE 802.3(Ethernet), 802.4(Token Bus), 802.5(Token Ring), and 802.1(Wireless LAN). 4. Network Layer (9 hours) 4.1 Internetworking &devices: Repeaters, Hubs, Bridges, Switches, Router, Gateway 4.2 Addressing: Internet address, classful address 4.3 Subnetting 4.4 Routing: techniques, static vs. dynamic routing , routing table for classful address 4.5 Routing Protocols: RIP, OSPF, BGP, Unicast and multicast routing protocols 4.6 Routing algorithms: shortest path algorithm, flooding, distance vector routing, link state routing; Protocols: ARP, RARP, IP, ICMP 5. Transport Layer (5 hours) 5.1 The transport service: Services provided to the upper layers 5.2 Transport protocols: UDP, TCP 5.3 Port and Socket 5.4 Connection establishment, Connection release 5.5 Flow control & buffering 5.6 Multiplexing & de-multiplexing 5.7 Congestion control algorithm: Token Bucket and Leaky Bucket Transport Layer 6. Application Layer (5 hours) 6.1 Web: HTTP & HTTPS BY: ER. ANKU JAISWAL 6.2 File Transfer: FTP, PuTTY, WinSCP 6.3 Electronic Mail: SMTP, POP3, IMAP 6.4 DNS 6.5 P2PApplications 6.6 Socket Programming 6.7 Application server concept: proxy caching, Web/Mail/DNS server optimization 6.8 Concept of traffic analyzer: MRTG, PRTG, SNMP, Packet tracer, Wireshark. 7. Introduction to IPV6 (4 hours) 7.1 IPv6- Advantages 7.2 Packet formats 7.3 Extension headers 7.4 Transition from IPv4 to IPv6: Dual stack, Tunneling, Header Translation 7.5 Multicasting 8. Network Security (7 hours) 8.1 Properties of secure communication 8.2 Principles of cryptography: Symmetric Key and Public Key 8.3 RSA Algorithm, 8.4 Digital Signatures 8.5 Securing e-mail (PGP) 8.6 Securing TCP connections (SSL) 8.7 Network layer security (IPsec, VPN) 8.8 Securing wireless LANs (WEP) 8.9 Firewalls: Application Gateway and Packet Filtering, and IDS Practical: 1. Network wiring and LAN setup 2. Router Basic Configuration 3. Static and Dynamic Routing 4. Creating VLAN 5. Router access-list configuration 6. Basic Network setup on Linux 7. Setup of Web Server, DNS Server, DHCP Server 8. Virtualizations BY: ER. ANKU JAISWAL CHAPTER 1 - INTRODUCTION TO COMPUTER NETWORK 1. INTRODUCTION A computer network is a group of computer systems and other computing hardware devices that are linked together through communication channels to facilitate communication and resource-sharing among a wide range of users. Networks are commonly categorized based on their characteristics. Application of Networks • Facilitate communication via email, video conferencing, instant messaging, etc. • Enable multiple users to share a single hardware device like a printer or scanner • Enable file sharing across the network • Allow for the sharing of software or operating programs on remote systems • Make information easier to access and maintain among network users There are many types of networks, including: • Local Area Networks (LAN) • Personal Area Networks (PAN) • Home Area Networks (HAN) • Wide Area Networks (WAN) • Campus Networks • Metropolitan Area Networks (MAN) • Enterprise Private Networks • Internetworks • Backbone Networks (BBN) • Global Area Networks (GAN) • The Internet LAN This is the abbreviation for Local Area Network which is when there are multiple computers and peripheral devices connected to a campus or in an office or other room. They are sharing a common connection that has 10-100 Mbps data transmission speed and are connected by Ethernet cables, usually running on high-speed internet connection. LAN computer terminals may be physically connected using cables or setup wireless, thus called WLAN. LAN is less expensive than WAN or MAN. WAN This is the abbreviation for Wide Area Network and is the biggest network which can interconnect networks around the world. Companies such as Microsoft or other worldwide organizations utilize WAN connection between their various branches by communicating via microwave satellites. BY: ER. ANKU JAISWAL WAN has a data transmission speed of 256Kbps to 2Mbps, offering a faster speed than LAN or MAN. WAN is used to connect LANs that are not in the same area and is more expensive than LAN or MAN. MAN MAN is the abbreviation for Metropolitan Area Network and bigger than LAN network. It connects computer users that are in a specific geographical area. An example of MAN is your cable television or a large university. MAN’s data transmission speed is 5-10Mbps, which is faster and more expensive than LAN but slower and smaller than WAN. 1.1. USES OF COMPUTER NETWORK The computer networks are playing an important role in providing services to large organizations as well as to the individual common man. Service Provided by the Network for Companies: • Many organizations have a large number of computers in operation. These computers may be within the same building, campus, city or different cities. • Even though the computers are located in different locations, the organizations want to keep track of inventories, monitor productivity, do the ordering and billing etc. • The computer networks are useful to the organizations in the following ways: 1. Resource sharing. 2. for providing high reliability. 3. To save money. 4. It can provide a powerful communication medium. The computer networks offer the following services to an individual person: 1. Access to remote information 2. Person to person communication 3. Interactive entertainment. Access to remote information: Access to remote information involves interaction· between a person and a remote database. Access to remote information comes in many forms like: (i) Home shopping, paying telephone, electricity bills, e-banking, on line share market etc. (ii) Newspaper is. On-line and is personalized, digital library consisting of books, magazines, scientific journals etc. (iii)World Wide Web which contains information. About the arts, business, cooking, government, health, history, hobbies, recreation, science, sports etc. BY: ER. ANKU JAISWAL Interactive entertainment: Interactive entertainment includes: (i) Multi person real-time simulation games. (ii) Video on demand. (iii) Participation in live TV programs likes quiz, contest, discussions etc. In short, the ability to merge information, communication and entertainment will surely give rise to a massive new industry based on computer networking. 1.2. NETWORKING MODEL a) Client-Server Model Client-server architecture (client/server) is a network architecture in which each computer or process on the network is either a client or a server. Servers are powerful computers or processes dedicated to managing disk drives (file servers), printers (print servers), or network traffic (network servers). Clients are PCs or workstations on which users run applications. Clients rely on servers for resources, such as files, devices, and even processing power. Fig: Client-Server model BY: ER. ANKU JAISWAL b). P2P model Peer-to-peer (P2P) is a decentralized communications model in which each party has the same capabilities and either party can initiate a communication session. Unlike the client/server model, in which the client makes a service request and the server fulfills the request, the P2P network model allows each node to function as both a client and server. In its simplest form, a peer-to-peer (P2P) network is created when two or more PCs are connected and share resources without going through a separate server computer. Most P2P programs are focused on media sharing. c) Active network An active network is a network in which the nodes are programmed to perform custom operations on the messages that pass through the node. For example, a node could be programmed or customized to handle packets on an individual user basis or to handle multicast packets differently than other packets. Active network approaches are expected to be especially important in networks of mobile users. "Smart packets" use a special self-describing language that allows new kinds of information to be carried within a packet and operated on by a node. 1.3. PROTOCOLS AND STANDARDS A protocol is the special set of rules that end points in a telecommunication connection use when they communicate. Protocols specify interactions between the communicating entities. Protocols exist at several levels in a telecommunication connection. For example, there are protocols for the data interchange at the hardware device level and protocols for data interchange at the application program level. In the standard model known as Open Systems Interconnection (OSI), there are one or more protocols at each layer in the telecommunication exchange that both ends of the exchange must recognize and observe. Protocols are often described in an industry or international standard. Standard is a common set of rules. BY: ER. ANKU JAISWAL NEED OF LAYERED ARCHITECTURE IN COMPUTER NETWORK • It simplifies the design process as the functions of each layers and their interactions are well defined. • The layered architecture provides flexibility to modify and develop network services.