By Ken Leyba
Most modern GNU/Linux distributions are secure with their default minimal installs, whether desktop or server, while some distributions are designed specifically with security in mind. However, any GNU/Linux distribution that needs services available to other users or systems will need either enhanced or configurable security. There are other situations in which added security is beneficial; for example, a large environment, while secure to the outside world, would be enhanced with additional security measures in place.
There are typically only a few types of networks in smaller environments. A single computer that communicates with the internet via a single cable modem or DSL line, or a single internet connection that is shared between multiple computers are two examples (figure 1). Ideally, the internet connection is protected with a standalone firewall: either a firewall appliance or dedicated GNU/Linux firewall such as IPCop. Due to cost, location or space concerns the ideal is not always possible and the firewall must be on a single workstation or multiple purpose workstation that acts as a gateway for the other systems. In a larger environment with multiple operating systems, some insecure by default, a personal firewall enhances security, especially if a workstation contains sensitive information.