A firewall is a set of products that protects the internal network from external threats.

  • The firewall allows traffic in or out of the network based on a set of rules.
  • A successful firewall should become a network choke point.
  • A firewall can be made up of more than one network device or service.
  • There are several types: packet filter, application gateway, circuit-level gateway, and proxy server.
  • A firewall may be able to provide a Virtual Private Network solution.