What is a Firewall?
Firewall is the first line of defense for a network, positioned between networks to monitor traffic and decide whether to allow or block data. It protects against malware, phishing attacks, denial of service (DoS) threats and other types of malicious traffic. It also prevents unauthorized access to the network and sensitive information. It can be hardware, software or a combination of both, depending on the type and deployment model chosen.
A network firewall typically sits between the LAN and WAN, while a host-based firewall runs on individual hosts. The router that brings internet service to your home or office is a hardware firewall, while the operating system on your computer is often a software firewall.
First-generation firewalls began to appear in the 1980s. They examine packets of data on a packet-by-packet basis and decide to allow or block traffic based on criteria, such as source and destination IP addresses, port numbers and protocol types.
Second-generation firewalls, also known as stateful firewalls, started to emerge in the early 2000s. These firewalls track the state of active connections and evaluate traffic in context to detect more sophisticated attack vectors.
Third-generation firewalls, also called next-generation firewalls (NGFW) started to appear in 2010. These firewalls combine traditional capabilities with advanced features like IPS and traffic decryption. They also support hybrid cloud environments and deliver mature visibility, unified policy management and automation capabilities. Keeping your firewalls up to date and following best practices can help minimize security breaches and other vulnerabilities.