Firewalls protect your computer from unauthorized access when you're connected to the Internet. Both hardware and software firewalls examine connection requests and, by applying a set of configurable rules, deny or allow the connection. The hardware required for a firewall is available as a dedicated unit; however, a reliable secure firewall can be created from basic PC hardware.
Chassis
Dedicated firewall chassis are designed to fit inside a computer rack, but you can use a spare PC case to house your firewall's components. The case must be compatible with the chosen motherboard and have enough room for the network interface cards.
Motherboard
The motherboard must fit the chassis, have at least two slots for the network cards and have an on-board video card. Using high-specification PCI (peripheral component interconnect) video card adapters is not recommended, as these produce more heat and the basic functionality required to operate the firewall doesn't warrant them. The motherboard should run at 133 Mhtz at minimum.
