Network Firewalls

Network firewalls are a set of related programs that protect the resources of a private network from users from other networks. (The term also implies the security policy that is used with the programs.)  Firewalls are typically located at the network gateway server.  Any enterprise (company, organization, etc.) with an intranet that allows its workers access to the wider Internet should install a firewall to prevent outsiders from accessing its own private data resources, and for controlling what outside resources its own users have access to; as should companies specializing in e-commerce (especially those that accept and retain credit card and other personal information).  In addition to their security aspects, firewalls can also be used to store open access data about a companies products and services, files to download, bug fixes, and so forth. Functionally, firewalls work closely with a router program to examine each network packet and determine whether to forward it toward its destination. Firewalls also include or work with a proxy server that makes network requests on behalf of workstation users.

A firewall is often installed in a specially designated computer separate from the rest of the network so that no incoming request can get directly at private network resources. This separation, within the network, allows the firewall to isolate any damage (real or perceived) located on one part of the network (e.g., viruses, worm programs, damaged files) from spreading throughout the rest of the system. Without firewalls, network security problems can rage out of control; and in addition to breaching security, drain valuable server resources, bogging down the entire network.

There are a number of firewall screening methods. The simplest form screens requests to make sure they come from acceptable (previously identified) domain names and Internet Protocol addresses. For mobile users, firewalls allow remote access into the private network by the use of secure logon procedures and authentication certificates.

Specific features of firewalls include logging and reporting, automatic alarms at given thresholds of attack, and a graphical user interface for controlling the firewall.

While firewalls can provide a high level of protection and security, they can only handle attacks that actually try to come through them.  They are not designed to stop internal security breeches, or viruses entering the network via employee-installed floppy disks.    For a firewall (and indeed an entire network security system) to work properly, there must be consistent overall organizational security architecture.

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