What is a Firewall?
Firewalls are network tools that provide a layer of defense, allowing only authorized data to pass and blocking malicious or unwanted traffic. Properly configuring firewall rules is vital for your organization’s cybersecurity, and regular review and updates are a must to maintain optimal protection. Off-the-shelf firewalls usually ship with preconfigured rulesets to reduce deployment time and ensure adherence with industry best practices.
Firewalls can be implemented in hardware, software, or virtual in the cloud, but they all have the same goal of preventing unauthorized access to an internal network. Firewalls can be configured to filter data on a packet-by-packet basis and/or inspect application layer protocols for signs of threats. They can also be configured to inspect incoming and outgoing communications on the standardized OSI network protocol level to prevent direct connections between networks.
The first generations of firewalls started out as packet filters that examine the packets or bytes of data transferred between network computers. This technology helped to vet external connections before they made contact with network systems and allowed for the development of anti-virus products.
The second generation of firewalls added stateful inspection capabilities, which allows or blocks traffic based on the status of the connection, port, and communication protocol. This helps to mitigate a common attack known as port scanning, where attackers attempt to connect to open ports within a network to gain entry and move around undetected. It also allows for the creation of web application firewalls (WAFs) that act as intermediaries between clients and servers, examining requests for web services to detect malware or unauthorized activity.