Firewall technology has been around to protect networks for quite some time. Over the generations this technology has evolved into several distinct types. Knowing the different type of firewall technology will give you confidence in deciding which type of firewall to purchase. Common types of firewalls are as follows:

• Static packet filtering

• Circuit level

• Application layer

• Dynamic packet filtering

Static Packet Filter

A static packet filter firewall examines each packet against a set of rules. If the firewall rules allow this type of packet, it will then allow the packet to pass through. If the rule does not allow the packet then the packet is dropped or rejected depending on how the firewalls rules are set.

Circuit Level

This type of firewall validates the fact that a packet is either a connection request or a data packet belonging to a connection or a virtual circuit. Circuit level firewalls work on the transport level of the protocol stack. They are fast and transparent, but do not check the data in the packet.

Application Layer

A application Layer Firewall evaluates network packets for valid data at the application layer before allowing a connection. These types of firewalls determine if a connection to a requested specific application is permitted such as, email or internet access. Application Layer Firewalls can also validate other security items that appear only within the application layer data, like user password and service requests.

Dynamic Packet Filtering

Dynamic Packet Filtering Firewalls also known as stateful firewalls keep track of the actual communication process through the use of a state table. This type of firewall operations at layers 3, 4, and 5. Dynamic Packet Filtering firewalls can inspect and track each connection passing through the firewall on all interfaces. This technology allows the firewall to confirm they are valid packets.

It has become increasingly import for growing business and home users to implement a firewall solution to protect computers and user data. Over the years the firewall technology has evolved. It’s important to understand the different type of firewall technology that is out today. Having this knowledge will help your purchase the right firewall solution for your company or personal use.

Matt has been a Network Administrator for over 5 years now. You can check out his latest website Active Directory Tools which provides a list of useful tools for Network Administrators.