In An Introduction to Network Firewalls

A computer and a network without a firewall system can easily be attacked by the hackers, intruders, viruses and spyware. A firewall is a security system, software or hardware that provides a security boundary around a computer system or a computer network and it protects the computer from internal and external security threats such as unauthorized user access and hackers attacks.  There are some positive and negative effects of the firewall software and hardware.  Among the positive effects are the user authentication, auditing and security and the negative effects include network bottleneck, single point of failure and increased management.

A firewall software or hardware is usually installed or attached on the gateway computer that is directly exposed to the external network such as internet.  Firewall limits the access to the computer and the network resources. A firewall computer is a trusted and secure computer between the internal and external network.  In the following section you will find the best paid and free firewall software and hardware reviews.