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 network and an untrusted network, such as the Internet, and its main purpose is to allow non-threatening traffic in and to keep dangerous traffic out. Firewalls can be categorized as network-based or host-based systems). Network-based firewalls are positioned between two or more networks, typically between the local area network (LAN) and wide area network (WAN), and their basic function is to control the flow of data between connected networks). Host-based firewalls, on the other hand, are installed on individual computers or devices and control the traffic that enters or leaves that device).
Firewalls have been around since the late 1980s and started out as packet filters, which were networks set up to examine packets, or bytes, transferred between computers. Today, firewalls have come a long way as technology has developed throughout the decades. There are different types of firewalls, including:
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Packet Filter Firewall: This is the first reported type of network firewall, which inspects packets transferred between computers. The firewall maintains an access-control list which dictates what packets will be looked at and what action should be applied, if any, with the default action set to silent discard).
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Application Firewall: This type of firewall hooks into socket calls and is also referred to as socket filters. It filters traffic based on the application that is generating the traffic).
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Stateful Inspection Firewall: This type of firewall allows or blocks traffic based on state, port, and protocol. It monitors all activity from the opening of a connection until it is closed. Filtering decisions are made based on both administrator-defined rules as well as context, which refers to using information from previous connections and packets belonging to the same connection.
Firewalls are a necessary part of any security architecture and take the guesswork out of host-level protections and entrust them to your network security device. They are used to restrict access to particular network resources or services, monitor network activity, and guard against unwante...
