TABLE OF CONTENTS When it comes to selecting a firewall there are a host of factors to consider. For commercial offerings there is the up front cost in addition to ongoing maintenance costs, which in comes cases can be considerable. For free offerings, however, one of the first considerations is what OS you want to run the firewall on. This will impact how it is managed, and while the capabilities of the firewalls are likely similar, the implementation details will be very different. Most firewalls (commercial and free) run on either Windows or Linux. Some commercial offerings run on their own base system (e.g., Cisco PIX). The underlying Linux system has been so heavily modified it is now considered proprietary In the case of a Linux firewall, you also have the option of installing the firewall software on a Compact Disk Read Only Memory (CD-ROM) or pen drive. These steps are discussed in more detail in the following sections, along with specific configuration examples for setting up a free firewall on both Linux and Windows.
Another consideration is whether the firewall decision-making logic is run as software that sits on top of another functional system, or if the firewall is a dedicated piece of hardware. In the case of a Cisco PIX firewall, the smallest models are the size of a small cigar box and there is no OS other than the PIX software. This is a dedicated hardware device used to perform the firewall function, also called...
