|  |  | 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.