Hardware firewalls protect computers and networks from unauthorized access. Different types include packet filtering, stateful inspection, network address translation, and application layer gateways. They examine data packets and filter them based on rules set by the network administrator. NAT firewalls hide computers behind a public IP address, while application layer gateways act as proxies and regulate traffic closely.
A hardware firewall is a physical device that connects a computer or network to the Internet, using some advanced techniques to protect it from unauthorized access. Wired routers, broadband gateways, and wireless routers all incorporate hardware firewalls that protect every computer on the network. Hardware firewalls can be distinguished by the techniques they use to protect a computer network and the different types are packet filtering, stateful packet inspection, network address translation, and application layer gateways.
The packet filtering firewall examines all data packets traveling to and from the system. Forwards data based on a set of rules defined by the network administrator. This hardware firewall examines the packet header and filters packets based on source address, destination, and port information. If the packet does not comply with the rules or meets the blocked criteria, it is not allowed to pass through to your computer or network.
The Stateful Inspection firewall goes beyond packet filtering to track information about the state of network connections to determine which data packets are allowed to pass through. It is also known as dynamic packet filtering or SPI (Stateful Packet Inspection). This hardware firewall monitors where the packet is coming from to figure out what to do with it. See if the data was sent in response to a request for more information or if it just appeared. Packets that don’t match a known connection state are rejected
A network address translation (NAT) firewall hides a computer or network of computers from the outside world by presenting a public Internet Protocol (IP) address to the Internet. The firewall IP address is the only valid address in this scenario, and this is the only IP address presented for all computers on the network. Each computer within the network is assigned an IP address that is valid only within the private network. This hardware firewall is very effective because it presents the Internet with only one public IP address for any number of users on a network.
When a computer inside the network protected by a NAT firewall makes a request for information, the firewall observes the request, notes the internal IP number, forwards the request using its IP address and sends the received information to the specific computer inside of the network. An application layer gateway effectively makes a computer behind it invisible to the Internet by acting as a proxy and doing all data transfers on behalf of the computer. It regulates traffic very closely, allowing only certain commands to pass, limiting access to files and triggering alarms under certain conditions. This hardware firewall is usually implemented on a separate computer on a network that only acts as a proxy. It is quite sophisticated and is considered to be one of the most secure types of hardware firewalls.
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