A firewall is a hardware/software system that manages the flow of information between the Internet and an organization's private network. Firewalls can prevent unauthorized Internet users from accessing private networks connected to the Internet, especially intranets, and can block some virus attacks -- as long as those viruses are coming from the Internet. A firewall can separate two or more parts of a local network to control data exchange between departments. Components of firewalls include filters or screens, each of which controls transmission of certain classes of traffic. Firewalls provide the first line of defense for protecting private information, but comprehensive security systems combine firewalls with encryption and other complementary services, such as content filtering and intrusion detection.
Firewalls control access from a less trusted network to a more trusted network. Traditional implementations of firewall services include:
- Screening routers, (the Protocol Firewall)
- Application gateways (The Domain Firewall)
A pair of Firewall Nodes provides increasing levels of protection at the expense of increasing computing resource requirements. The Protocol Firewall is typically implemented as an IP Router.
See Also
Additional Resources
- (in English) ESS