Firewalls Case

There are three main classes of firewalls and each protects a network in various ways. The three main classes of firewalls are packet filter firewalls, application and circuit gateway (proxy) firewalls, and stateful inspection (smart filter) firewalls. Packet filtering firewalls will track the source and destination addresses of IP packets, and are known as first generation firewalls. This type of firewall will only permit the packets to pass through the firewall based on rules set by the network manager. Used as part of a VPN they limit traffic passing through a tunnel from one network to another. This behavior allows one to refine the control on traffic between the two networks. Application and circuit proxy (ACP) firewalls are more secure than packet filtering firewalls as they examine all layers of the OSI model simultaneously whereas the packet filtering firewalls only examine lower layers on the OSI model. ACP firewalls allow a user to use a proxy server to communicate with secure systems which will allow valuable data and servers to be hidden from potential attackers. ACP firewalls are made to use proxy agents where an agent is programmed to handle only one type of traffic (such as FTP or TCP). The more types of traffic that a user would want to pass through the proxy server, the more proxy agents the user then needs to load and run on the selected machine. Stateful inspection firewalls allow great security along with fast performance using a technique called Stateful Multi-Layer Inspection (SMLI). This allows tighter security on the network while still making it easier and less expensive to use without slowing down the network. SMLI firewalls can be applied across multiple kinds of protocols and have many features and functions that are easy to use. Like ACP firewalls, SMLI firewalls examine all layers of the OSI model. However, instead of using a proxy it uses traffic-screening algorithms which allow for high throughput using data parsing. SMLI firewalls