With the explosion of the public Internet and e-commerce, private computer, and computer networks, in for adequately secure, are increasingly vulnerable to damaging attacks. Growing numbers of customers, suppliers, partners and employees are conducting business online and accessing the corporate network. The increased openness leaves networks dangerously susceptible to attacks from hackers, disgruntled employees, competitors seeking confidential information, and viruses. All computer users, from the most casual Internet surfers to large enterprises, could be affected by network security breaches. Security breaches cost businesses many millions of dollars in downtime and lost productivity each year, and erode the confidence and goodwill of current and potential customers. However, security breaches can be prevented.