What is a Firewall?
A firewall is a cybersecurity tool that monitors and filters data entering or leaving your computer network based on predefined security rules. This helps to prevent cyber attacks and malicious programs like viruses and malware. Firewalls can be software or hardware devices and can help protect your business and personal devices from cyberattacks.
Firewalls are able to prevent harmful traffic from entering your networks by analyzing data and comparing it against predefined rules that have been set up by you or your network administrator. Firewalls can check the type of transmission, the source address, and the application data is being used for to determine whether or not it meets your cybersecurity standards. The firewall can then open or close your network gate based on its findings.
There are two main types of firewalls, network-based and host-based. Network-based firewalls guard entire networks and are typically hardware devices, while host-based firewalls protect individual host computers and are often software applications. Network-based firewalls can be broken down into two categories, packet filtering and stateful inspection. Packet filtering firewalls examine data packets in isolation, relying on their IP addresses and ports to distinguish between malicious and benign packets.
Stateful inspection firewalls (also known as dynamic or adaptive) monitor a connection at the OSI session layer, which keeps track of every interaction between a trusted client or server and untrusted hosts. This firewall type allows it to determine when a packet is related to another in a given network, making it one of the most versatile and popular types of firewalls. Proxy firewalls, which combine application-level inspection, or deep packet inspection (DPI), with stateful inspection, are unique in that they read and filter the actual application protocols of web pages and other network traffic.