What Is a Firewall?
Firewalls protect networks from cyberattacks by monitoring data coming into and out of systems. They use pre-established rules to allow or block data packets based on their content and other indicators. They also offer security services like encryption, authentication, and data loss prevention.
Firewall technology has been around since the late 1980s, starting out as packet filters that examined data sent across a network. Attacks from the internet in the mid 1990s affected most businesses and fueled demand for anti-virus products and firewalls. As attacks become more advanced, Next Generation Firewalls (NGFW) are emerging to improve the protection they offer to businesses.
The main function of a firewall is to monitor data that comes into and out of a network, detecting malicious activities and other threats. They inspect data packets (pieces of information for Internet transfer) at various levels of a network and then make decisions based on pre-established rules. For example, packet filtering firewalls examine data in isolation without context, while stateful inspection firewalls check whether one packet is related to another. Other types of firewalls include circuit-level gateway firewalls that provide security by monitoring TCP handshakes, and proxy firewalls that inspect data at the application layer of a network.
A firewall’s effectiveness depends on its configuration, network hardware, and software. It is crucial to keep firewalls updated to address new threats as they arise. Additionally, firewalls should be optimized to reduce unnecessary processing and boost performance. When improperly configured, a firewall can be used for unethical purposes such as government censorship and to track employees’ online activity, leading to violations of privacy and personal freedoms.