CSI 120-74 Business Data Networks and Communications
November 28, 2004
Why is a firewall valuable?
Many Corporations are using computers that are connected to communication networks, such as intranets, extranets, and the Internet. Sensitive corporation data is transferred back and fourth between different sites and there is a big thread of electronic attacks. Because so many people have access to the data, a corporation has to protect its assets (data, software, etc.). Furthermore, a firewall helps to control information flow between sites and therefore assists in preventing congestions on the network. Using a firewall is an important part of a company's risk management strategy. There should be a maximum thread protection with minimum risk, high performance, and ease of administration.
What does it Do
A firewall may consist of several pieces of equipment and may include a router, a gateway server, and an authentication server.
Firewalls monitor incoming and outgoing traffic and filter, redirect, repackage, and/or discard packets. Packets may be filtered based on their source and destination IP address, source and destination TCP port numbers, setting of bits in the TCP header, and so on.
By using firewall boxes and software placed between the networked computers, corporations are able to protect their assets. The firewall examines, filters, and reports on all information passing through the network to ensure its appropriateness.
Firewalls are also important since they can provide a single ``check point' where security and audit can be imposed. Unlike in a situation where a computer system is being attacked by someone dialing in with a modem, the firewall can act as an effective ``phone tap'' and tracing tool. Firewalls provide an important logging and auditing function; often they provide summaries to the administrator about what kinds and amount of traffic passed...