# 5. Concept of Computer Network and Network Security System

### **5.1 Introduction to Computer Networks and Physical Layer**

* Networking Model, Protocols and Standards
* OSI Model and TCP/IP Model
* Networking Devices (Hubs, Bridges, Switches, and Routers)
* Transmission Media

***

### **5.2 Data Link Layer**

* Services, Error Detection and Corrections, Flow Control
* Data Link Protocol
* Multiple Access Protocols
* LAN Addressing and ARP (Address Resolution Protocol)
* Ethernet, IEEE 802.3 (Ethernet), 802.4 (Token Bus), 802.5 (Token Ring), PPP (Point to Point Protocol)
* CSMA/CD
* IEEE 802.3 Standard
* Wireless LANs

***

### **5.3 Network Layer**

* Addressing (Internet Address, Classful Address), Subnetting
* Routing Protocols (RIP, OSPF, BGP, Unicast and Multicast Routing Protocols)
* Routing Algorithms (Shortest Path Algorithm, Flooding, Distance Vector Routing, Link State Routing)
* Network Layer Protocols: ARP, RARP, IP, and ICMP
* IPv6 (Packet Formats, Extension Headers, Transition from IPv4 to IPv6, Multicasting)

***

### **5.4 Transport Layer**

* The Transport Service, Transport Protocols
* Port and Socket, Connection Establishment & Connection Release
* Flow Control & Buffering, Multiplexing & De-multiplexing
* Congestion Control Algorithm

***

### **5.5 Application Layer**

* Web (HTTP & HTTPS), File Transfer (FTP, PuTTY, Win SCP)
* Electronic Mail, DNS, P2P Applications
* Socket Programming, Application Server Concept
* Concept of Traffic Analyzer (MRTG, PRTG, SNMP, Packet Tracer, Wireshark)

***

### **5.6 Network Security**

* Types of Computer Security, Types of Security Attacks
* Principles of Cryptography, RSA Algorithm
* Digital Signatures, Securing E-mail (PGP)
* Securing TCP Connections (SSL), Network Layer Security (IPsec, VPN)
* Securing Wireless LANs (WEP), Firewalls