Understanding Firewall and its Functions

The term “firewall” (also known as “fire retaining wall”) was inspired by a physical firewall that is designed to slow the spread of fire from its source. The same concept is used in a network firewall where it prevents unauthorised users from gaining access to the network and its services through other networks. You can consider a firewall as a form of digital fence put up on your computer or network to keep dangerous content out and unauthorised access out. A firewall is a network security system, normally in the form of software and/or hardware, that monitors and filters incoming and outgoing traffic from entering a private network based on a set of rules established by an organisation. The most basic level firewall can work as a barrier that separates a private network from the public internet to prevent harmful traffic from gaining unauthorised access to restricted data.  A firewall serves as a barrier between two networks based on a pre-determined set of rules. It detects and inhibits attempts to obtain access to your operating system, as well as unwanted traffic from unidentified sources to help safeguard your network and information. This involves blocking unsolicited incoming network traffic and authenticating access by scanning network traffic for malicious content such as hackers and viruses. In short, a firewall only accepts inbound traffic that has been set to accept by a firewall. Firewalls can function as a network security guard to prevent sensitive information from being leaked without permission, log user activity (log files), and prevent data from being modified by third parties. Firewalls are classified into numerous categories based on their structure and functions. Depending on the size of your network and the level of protection you require, you can use one of the following firewalls. Packet Filtering Firewall A packet-filtering or static firewall is the most basic type of firewall designed for smaller networks. As the name suggests, it functions at the packet level by examining every data packet that enters or exits the network. It examines these packets based on the IP protocol, IP address, and port number and decides whether to accept or reject them.  Proxy Firewall A proxy firewall, also known as a gateway firewall, is an early type of firewall device that filters messages at the application level to safeguard your network security. It basically acts as a bridge or middleman between your internal network and external web servers and it’s more secure because it analyses incoming traffic using deep packet inspection technology. A proxy firewall can stop information from flowing between your internal network and the network outside your walls because it understands the application in use. Stateful Inspection firewall A stateful inspection firewall is a dynamic packet filtering that keeps track of active connections to decide which network packets to let through the firewall. It analyses a packet’s layers by recording the IP address and port number and keeps track of all activities from when a link is established until it is terminated. Filtering decisions are based on both administrator-defined criteria and context. Unified Threat Management (UTM) Firewall  A unified threat management firewall integrates the capabilities of a stateful inspection firewall, intrusion prevention, and antivirus into a single software. Under the UTM umbrella of services, additional services such as cloud management may be integrated. Next-Generation Firewalls (NGFW) Next-generation firewalls are implemented to combat modern and advanced threats such as complex malware and application-layer attacks. It has higher security levels that go beyond ordinary packet filtering to examine a packet entirely. This includes checking the packet header, contents and source of the packet.  Virtual Firewalls A virtual firewall is a device that can be utilised in both private and public cloud-based systems. It is often deployed as a virtual appliance in a private or public cloud to monitor and safeguard traffic. This firewall evaluates and manages internet traffic across physical and virtual networks. It’s a good idea to have a firewall in place if you use the internet because they act as the first line of defence, helping to secure your computer and personal information from cyber threats.