A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a trusted internal network and an untrusted external network, such as the internet, to prevent unauthorized access and protect against cyber threats.
Firewalls can be implemented as hardware, software, or a combination of both. They can also be configured to perform different functions, including packet filtering, stateful inspection, and application-level gateway.
Packet filtering firewalls examine each incoming and outgoing packet and compare it against a set of predefined rules. If the packet matches the rule, it is allowed to pass through the firewall. Otherwise, it is blocked.
Stateful inspection firewalls monitor the state of a network connection and determine whether to allow or block traffic based on the connection’s history and status. This type of firewall is more secure than packet filtering because it can identify and block unauthorized traffic that might be disguised as legitimate traffic.
Application-level gateway firewalls are designed to filter specific types of traffic, such as HTTP or FTP, and can inspect the content of the traffic to identify potential threats. This type of firewall is often used in conjunction with other security measures, such as intrusion detection and prevention systems.
Examples of firewalls include hardware firewalls, such as those found in routers and switches, and software firewalls, such as those built into operating systems or third-party firewall software. Firewalls are used in both home and enterprise networks to provide an additional layer of security against cyber threats.
