Demilitarized zones

In military and political situations there are buffer zones, demilitarized zones, between areas of unrest. One good example of this is the demilitarized zone between North and South Korea.

Demilitarized zones, or DMZs, are also found in computer networks. A DMZ is a computer network that is accessible from two other computer networks that have no direct contact with each other. Often, one of these networks is the Internet and the other is a local, internal network. There is no direct connection between the Internet and the local network, but both of them can access an intermediate network, a demilitarized zone.

DMZs are often used for special servers, such as WWW servers, which must be accessible from two separate networks.

It is easiest to create a DMZ using one firewall; the figure below shows an example.

A DMZ can also be built as a network connected between two firewalls.