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INTERNET PROTOCOL ADDRESS FILTERING
CHAPTER ONE
1.0 INTRODUCTION
Computer networks have become increasingly popular since the emergence of the ARPANET in the 1960’s. The ARRPANET was a brainchild of the United State Department of Defence. Its origin could be traced to the quest for a network that would still be able to function even when some of the nodes are down. It was envisioned that this type of network would be capable of surviving a possible nuclear attack.
A computer network can be described as the interconnection of various computer systems. The goals users intend to attain through networking are basically the same irrespective of the network size (that is, the number of computer systems involved) or the topology- the mode of connection. The increasing popularity of computer networks is largely due to the immense benefits accrued from the interconnection of computer systems. Some of these benefits include:
Resource Sharing: Interconnecting computer system facilities the ease of sharing of resources such as data, programs, etc. all that is needed is just for one of the networked systems to have the resource available on it. Others could easily access the resource via the communication links between them.
Ease of Communication: Since the systems are connected via communicable links, it is very easy for a system to send or request information to or from others on the network.
Distributed Processing: Any job that should be handled by just one system can be broken down into various pieces, with each piece assigned to a system on the network. The results are then pooled together after all the systems have completed their assigned tasks to form the solution to the original problem. This makes processing of jobs faster and more efficient than when only a system is involved-that is, higher throughput and less turn around time.
Fault tolerance: Computer network facilitates fault tolerance since it is possible to program the network in such a way that jobs which any of the systems cannot complete (due to one form of failure or the other) can be easily taken over by another system. Finally, networking computers also guarantees reliability, back-up and fail-safe.
It might be tempting to believe that the highest possible level of security is required for the server system in the network. Before deciding how much effort or expense security of server files and directories warrants, one needs to decide how much the information is worth. The Length to which the attacker would be likely to go in order to obtain access to information varies instantly.
This study deals with Server security using IP address filtering and port scanner. The study implement an application that can be used to monitoring intrusion to the server files and directories using IP address filtering system and constant port scanner.
1.1 PROBLEM STATEMENT
In spite of all these appealing benefits and the efforts aimed at providing secure server operations, a lot of dangers are still posed to computer communication networks. These threats can be categorized into three as:
(i) External Attacks: External attacks are those that originate from the internet or form systems beyond the access device. External attacks can come in form of web page defacements, viruses, Trojan programs (also known as Trojan horse), and denial of services by malicious system crackers and cyber-terrorists. External attacks can occur against accessible services, systems and networks.
(ii) Internal Attacks: Internal attacks originate from within the organisation. They are mainly cause by disgruntled employees, curious users, and accidental misuse.
(iii) Physical Attacks: Physical attacks include simple actions such as unplugging the equipment, rearranging cables, or physically damaging components. Another aspect of physical attacks is the ability of a user to see and analyse network traffic that travels over the same network wires of the user’s desktop computer. This is known as electronic eavesdropping.
Since the goal of security is to guard against these potential threats, there is therefore a need to develop applications that guarantee security of server directories and files.
1.2 JUSTIFICATION OF RESEARCH
This research work is justified by the fact that the client/server approach is a very common networking solution adopted by most organisations. Since these organisations entrust vital and sensitive data and information to their client/server system, it is therefore necessary to provide an efficient security solution that can minimize or prevent the possibility of an attack on these systems. This study focused on IP filtering and port scanner as a means of detecting unauthorized intrusions and operations that may affect the security and effectiveness server systems within organizations.
1.3 AIMS
This research examines security issues and problems in computer networks in general and in client/server systems in particular. Various approaches used for providing security on networks are surveyed. The strengths and limitations of these approaches are also discussed. The study concludes by the formulation of an application gateway model for client/server systems.
OBJECTIVES
The objectives of this research work are therefore four-fold:
1. To explore the concept of security as pertaining to computer networks
2. To develop an application that watch for changes in a specified directory on the server.
3. To develop an application that can alert administrators of attempts to modify important files on the servers and verify the IP address of client system in order to access server files.
4. To design an application gateway model for managing security in a client/server environment that scan for open ports on the server system and constantly close them.
1.4 METHODOLGY
In line with the above stated objectives, an exploratory study of server systems security will be conducted. The methodologies to be used to achieve the research objectives include the following:
 Review of relevant literature in the subject area will be carried out.
 C# Programming language (.Net Framework) will be used as an implementation language and SQL server Database will be used as back end for designing the application gateway.
1.5 LIMITATION OF STUDY
This project covers security issues and problems in computer networks in general and in client/server systems in particular. The project aimed at developing server security application that the administrator of an organization can be used to monitor the files and directories on the server system. The scope of work does not cover other aspects of security implementations such the use of intrusion selection systems, scanners, spam detection, logging and auditing tools and encryption.