Computer Networks Configuration and Security in TCP/IP Networks

Abstract

A simple LAN Network in Packet Tracer version 6.3 has been created and configured, such that there is a connection throughout the entire network and also a basic secure connection against anyone who tries to breach it. The configurations and the network particularities are presented in the paper.

Packet Tracer is a program made by Cisco Systems that permits users to build network topologies. The software allows users to simulate the configuration of Cisco routers and switches through a simulated command line interface. Packet Tracer uses a drag and drop user interface. It allows users to add and remove simulated network devices.

Another option is the use of Omnet++ in order to simulate a network, which is extensible, modular, based on C++ simulation library components and frameworks.

A peer to peer application has been created where there exists a group of friends where, when someone sends a message, everyone in that group receives the message. The roles change. Sometimes a computer or a mobile phone will be a server, when the rest of the devices will be clients and sometimes the same device will be a client and one of the rest will be the server. in The peer’s exchange secret messages, like in a chat.

The client should register with his/her username to the application. Any user has a username and a password.  A user can “be friend” with other users. A list of his/her friends will appear on the user’s screen after logging in. A user can send messages which get automatically encrypted when they are sent to the receiver. The receiver will have the option to decrypt the message which he/she received.  For encryption, the Caesar cipher was used.

The application that was designed uses TCP/IP communication to connect several devices to a server. TCP is a connection-oriented protocol. In order to do communication over the TCP protocol, a connection must first be established between the pair of sockets. While one of the sockets listens for a connection request (server), the other asks for a connection (client). Once two sockets have been connected, they can be used to transmit data in both (or either one of the) directions.