A firewall is a method to monitor traffic in and out of a network system and can block or allow traffic much like border control in real life. The things that firewalls monitor, filter, and block are based on predetermined rules made by the owner when set up. Firewalls are crucial for businesses as they significantly interfere with bad actors from accessing private networks and stealing sensitive data. Bad actors may still be able to find other points of weakness but firewalls tend to do their job quite effectively.
Traditional firewalls were used to form a secure perimeter around a network. One that only allowed access with the appropriate authorization. Without this protection, practically anyone would be able to connect and enter into the network as they please. Installing a firewall will allow the owner to monitor things like IP addresses, port numbers, protocols, and packet content. Essentially, firewalls filter and track certain types or addresses that are entering the network, blocking or allowing based on restrictions made by the owner. Firewalls also come in various amounts of types that protect different systems. They all execute the same purpose or function but exist in different domains. Network-based firewalls (generally hardware) sit between an internal network and an external network with the priority of protecting the internal network. Host-based firewalls (generally software) are positioned within an individual system/device (computer, server, etc.) and filter incoming and outgoing traffic to the individual device. Proxy firewalls protect the user from potential threats that they may be trying to use. The firewall acts as a guardian to the user and allows or blocks websites that a user may be trying to enter, slightly mitigating the risk of being exposed to a malicious site.
Firewalls have the flexibility to be used in many different scenarios and domains. Despite this, almost all types have the same core functions, traffic filtering, access control, and logging and monitoring. The traffic filtering function allows the firewall to manage and inspect incoming and outgoing network traffic. Blocking certain IPs, port numbers, and protocols by default based on predetermined rules. Subsequently, firewalls are able to control traffic into or out of the network by only allowing certain IPs or port numbers through. All firewalls are able to log and track information about the traffic that passes through them including both allowed and blocked attempts. This can help owners/businesses detect suspicious activity or give information when investigating a potential threat.
Overall, firewalls are great at providing your network a secure foundation of security and should be considered when trying to protect sensitive information. However, due to the cyber world growing more advanced, sometimes a more layered approach is needed and additional security measures may be needed to further support the firewall.