1.0 INTRODUCTION 
The interconnection of computer with other related office equipments are finding increasing application in almost all field of human endeavour most especially the financial
sector. More and more banks are introducing the use of computer networks in their establishment. These provide for easy access to the information and services available in the organisation. 
Because of the high value of information, organisations now classify their data as well as putting a lot of effort to safeguard it. Networking is the vehicle for sharing information where as network security is a way to protect the information, information sharing cannot be constrained by physical or geographical location and today’s information has been made accessible to all by means of global network. For an organisation to become parts of this global network, it first need to have his own Local area network (LAN), which is then connected to the internet by means of a Wide area network (WAN). Computer security focuses on two main problems 
a. How to protect the physical equipment of the computer. 
b. How to protect against unauthorized use of the
Computer faculties by intruders. The objective of network security is to control access to corporate and government data residing on network services or transmitted over the LAN or WAN

1.1 BACKGROUND OF STUDY 
Diamond Bank Nigeria limited was established with the aim of providing banking services to the general public. It is first growing commercial bank incorporate with headquarter and about 8 or more branches scattered across the country, which included Imo, Abia, Calabar and Ibadan etc with a staff strength of more than 500 workers, they provide banking service to the public which include 
a. The handling of cash and provision of bank drafts 
b. The provision of facilities for the safe keeping of
Important document and title delds. 
c. The lending of money in the form of loans and
Overdrafts. 
d. The management of customers’ investment such as the
Purchase of stocks and shares and the receipts of periodic dividends. 
e. The transfer of funds to other places periodically

1.2 STATEMENT OF THE PROBLEM 
Diamond bank Nigeria limited has a large volume of information, which it has to handle efficiently in other to evolve efficiently corporate management and improved customer services. The information needed to carry out operation geared toward customer satisfaction must be highly secured and transmitted properly too. Since the banks uses computer network in their activities, there are bound to be threats to security which hinders work progress in the organisation, once the organisation launches it presence in the internet. 
Most banks lack awareness on how a network can be implemented, secured and maintained. Threats to network security are sometimes difficult to track and it won’t be easy to refuse the request of the attackers. Without refusing legitimate request for services. This attack comes from any connection that the bank has with the outside world, which included dial up moderns, and internet connection. So in order to adequately address security all possible avenues of entry must be identified and evaluated, also the security of every point must be consistent with stated policy on acceptable risk levels.

1.3 OBJECTIVE OF THE STUDY 
Networking is the backbone of accessing vital information the world has becomes a global village, sharing everything through networking. Networks requires a high level of security, which involves the technical and administrative safeguards required to protect a computer based system (hardware, personnel data) against the major hazards to which most computer system are exposed and to control accessed to information. The work is aimed at defining/providing a security system that will keep unauthorized uses from the protected areas of the network. This system will also prohibit potentially vulnerability services from entering or leaving the network. The system will also provide a location for monitoring security related events and adults as well as the overall security management of the network.

1.4 SIGNIFICANCE OF THE STUDY 
a. Network security and fire walls are useful in banking sectors and in their services 
b. It is useful to the banks in other sectors who would wish to use network security and firewall in their banks. 
c. It shows need for security in banking sectors.

1.5 SCOPE OF THE STUDY 
This study presents an overview of security system network and firewalls its highlights are on firewalls. Risks threats and vulnerability of network. It also concentrates on design of security system and network types.

1.6 LIMITATION OF THE STUDY 
This research was limited by the shortness of time giving rise to the limited study of network security and firewalls. Also the finance to embarked upon a higher level of research was not available. The bank on its part did not give out much information that would have really aided the writing of this work due to some security reasons. 
Additionally, this research was carried out at the Owerri branch office of diamond bank. Therefore the research was based on the branch section and not from the centre.

1.7 DEFINITION OF TERMS 
Network: Network in computing a number of computer and other devices that are connected together so that equipment and information can be snared. 
Security: These are activities that involves protecting a building or person against attack danger hazards 
Fire wall: Fire wall in computing is a part of a computer system that is designed to prevent people from getting at information without authority. But still allows them to received information that is sent to them. 
Computer: Computer is an electronic device that accept data, processes the data and gives information under automatic control 
Bank: This is an organisation that provides various financial service e.g. keeping or lending money. 
Personnel: Person who manage, design program, control or operate an information processing system and maintain access to the network. 
Policy: This layer defines the umbrella of the security program. It defines the policies of the organisation without a complete, effective and well implemented policy the security program cannot be complete. 
LAN: LOCAL AREA NETWORK
MAN: METROPOLITAN AREA NETWORK 
WAN: WIDE AREA NETWORK 
E-MAIL: ELECTRONIC MAIL 
FAX: FACSITAILE DOCUMENT TRANSMISSION