Type of firewalls

A firewall is a network security device that monitors and filters incoming and outgoing network traffic in accordance with previously established security policies in an organization. 

There are 3 types of firewalls:
*Packet filtering
*Stateful Filters
*Application layer

Packet filtering
A packet filtering firewall is a network security technique that regulates data flow to and from a network. Packet-filtering firewalls make processing decisions based on network addresses, ports, or protocols. Packet filtering firewalls are among the oldest firewall architectures.

Packet-filtering firewalls are very fast because there is not much logic going behind the decisions they make. They do not do any internal inspection of the traffic. One important function of packet filtering firewalls is to control and monitor network data to ensure its authenticity and compliance.

Stateful Filters
Stateful firewalls are capable of monitoring and detecting states of all traffic on a network to track and defend based on traffic patterns and flows. Stateful firewalls use modern extensions to track active connections, like transmission control protocol (TCP) and user datagram protocol (UDP) streams. By recognizing incoming traffic and data packets' context, stateful firewalls can better identify the difference between legitimate and malicious traffic or packages.

Application layer
An application firewall is a type of firewall that scans, monitors, and controls network, Internet and local system access and operations to and from an application or service.
Type of firewalls

What is a firewall in computing?

A firewall in a computer network performs a role that is very similar to that of a firewall in a building. Just as a firewall made out of concrete protects one part of a building, a firewall in a network ensures that if something bad happens on one side of the firewall, computers on the other side won’t be affected.

Firewall are used when there is a need for networks of varying levels of trust to communicate with one another. For example, a firewall typically exists between a corporate network and a public network like the Internet.

All traffic from inside to outside, and vice versa, must pass through the firewall. This is achieved by physically blocking all access to the local network except via the firewall. Only authorized traffic, as defined by the local security policy, will be allowed to pass.

The firewall itself is immune to penetration. This implies the use of a hardenedsystem with a secured operating system. Trusted computer systems are suitablefor hosting a firewall and often required in government applications.

Type of firewall
*Packet filtering
*Stateful Filters
*Application layer

A firewall can only restrict connections that go through it. It cannot protec from people who can go around the firewall, for example, through a dial-up server behind the firewall. It also cannot prevent an internal intruder from hacking an internal system.

A firewall is only as secure as the operating system on which it is installed. There are many flaws present in operating systems that a firewall cannot protect against. This is why it is important to properly secure the operating system and apply the necessary security patches before installing the firewall.
What is a firewall in computing?