Database Systems: Concepts, Design and Applications

14.5. Firewalls

A firewall is a system designed to prevent unauthorized access to or from a private network. Firewalls can be implemented in both hardware and software, or a combination of both. They are frequently used to prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets. All messages entering or leaving the intranet pass through the firewall, which examines each message and blocks those that do not meet the specified security criteria. Following are some of the firewall techniques that are used in database security:

1. Packet Filter: Packet filter looks at each packet entering or leaving the network and accepts or rejects it based on user-defined rules. Packet filtering is a fairly ...