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A firewall's basic task is to regulate some of the flow of traffic between different computer systems, mainly used to prevent network intrusion to the private network. A typical example of a no trust zone is the Internet, with your office network being the trusted zone. You need to have a firewall between the no trust zone and your trusted zone to make sure the unwanted visitors keep out. Larger organisations will create a zone with an intermediate trust level, situated between the Internet and a trusted internal network, is often referred to as a "perimeter network" or "demiliterised zone" (DMZ). Without proper configuration, a firewall is often worthless. Standard security practices dictate a "default-deny" firewall ruleset, in which the only network connections which are allowed are the ones that have been explicitly allowed. Unfortunately, such a configuration requires detailed understanding of the network applications and endpoints required for the organization's day-to-day operation. Many businesses lack this understanding, and implement a "default-allow" ruleset, in which all traffic is allowed unless it has been specifically blocked. This configuration makes inadvertent network connections and system compromise much more likely. |