Question

What is a firewall? what are the essential functions of it and what are some it disadvantages?

Answer 1

The primary purpose, responsibility, and essential functions of firewalls are to provide security, mostly from external networks such as the Internet. It is the combination of software and hardware to allow, deny, monitor, and block any and all data transmissions occurring from a specified internal network such as personal network, a PC, LAN, or a corporate company's or a university campus's network, or a home network going out to another target network or the Internet and the data transmissions sent from the external, public network such as the Internet or another specified network to the internal network. Firewalls evaluate, allow, or deny network traffic based on certain pre-defined rules set-up based on IP addresses or its range, port numbers, protocols, and few other factors. It provides good traffic management.

Firewalls defend against external threats refusing or denying unauthorized requests, transmissions, and connections to the router, network, application software, PC, server, virtual machines, etc from potential attackers such as hackers. Their responsibilities are packet filtering and they function as application proxies.

The different types of firewalls can be broadly classified as:
* Software firewalls or
* Hardware firewalls.

From an architectural design perspective, there are five types of firewalls:
* Packet-filtering firewalls.
* Stateful inspection firewalls.
* Circuit-level gateways.
* Application-level gateways or proxy firewalls.
* Next-gen firewalls.

A 'personal firewall' is a software layer that protects an individual computer which may be a part of the operating system or a separate software package which has to configured with relevant ports with their corresponding protocols closed or opened per pre-defined rules to filter the network traffic that comes in and goes out of a network.

A firewall is also used to secure Wi-fi wireless networks. A type of firewall is a host-based firewall. You could use firewalls on the router and even at the system level. Hence, a proper firewall mechanism with proper rules should be implemented in the operating system.

Disadvantages of firewalls:
* A firewall would not be able to protect users (internal users or employees of an organization) against malicious insiders or the people who are already inside. This is a firewall's one of the drawbacks. It usually restricts insiders causing them frustration, because of which at times in organizations, the rules set up in the firewall are quite liberal for internal communications.

* The purchasing and installing of hardware firewalls are very expensive and are not easily affordable.

* Installation and upgrade of hardware firewalls are difficult due to the ever-changing technology and environment.

* Firewalls do not offer user authentication.

* Firewalls are hard to manage and scale in complex environments.

* Backdoors may exist.

* May block required services such as FTP and Telnet required for employees in a company.