Firewall is a security system used to protect a computer network from external threats in computer networking. It typically appears as a device or software that monitors and controls network traffic.
The primary purpose of a firewall is to allow authorized or criteria-compliant network traffic to pass through while blocking unauthorized or malicious traffic. It is used to prevent unauthorized access, attacks, and malicious software on a computer network.
Firewall typically controls traffic from outside the network (incoming traffic from the internet) before it enters the internal network (company network or home network). This control can be based on factors such as the traffic’s source, destination, port, and content. For example, a firewall can block traffic from a specific port or allow traffic from a specific IP address.
There are different types of firewalls:
- Network-based Firewall: Devices placed at the entrances and exits of a network. Network-based firewalls are used to filter incoming and outgoing traffic.
- Host-based Firewall: Software that operates at the operating system level of a computer. Host-based firewalls are used to filter incoming and outgoing traffic on a computer.
- Application-based Firewall: A security device that monitors and controls the protocols and traffic used by applications and services.
Firewalls are considered a fundamental component of network security and are widely used to ensure the security of computer networks.