The most common threat to a company's information assets mainly come from human error, inappropriate disclosures, and sheer carelessness on the part of the company's employees. Hackers who do intentionally tamper with the company's network often do so because they are tempted by assets they know are poorly protected. Weak security policies present the image that a company does not truly value its assets, which in turn attracts the petty thief and curiosity seeker. Therefore, the preventive element of any network security system should include a strong and enforceable security policy for its employees to follow, re-enforced by a form of technical protection (Control Data, 1999).

Firewalls, antivirus programs and packet filtering devices are used to protect access to the network at the LADWP. But these tools alone do not provide adequate system security policy for system users, as mentioned above, that is based on the identification and prioritization of threats and assumed threats helps to maintain the network's health. The key feature of the policy is an ongoing training program that teaches all users the importance and value of including safe system user practices in their daily routine. Users are more likely to follow security practices if they understand the purpose of the practice and the consequences when these practices aren't used. Added to the training is a physical and electrical restriction of access to sensitive information and areas to users who have no business purpose for using such access. To ensure that the preventive measures are functioning effectively, regular audits of the security policy are performed. Log-on IDs are checked to verify their validity, and the users' activities are monitored to determine if the policies are being followed.

Detection

The next element of a network security system is system violation detection, or intrusion