Introduction to Firewall in Computer Network

A Firewall manages the secure in-flow and out-flow of data in a device. It monitors the network traffic and acts as a barrier between the trusted and untrusted network. 

The concept of Firewall is important for people interested in understanding the network security aspect of a computer device and also for those looking forward to strengthening their Computer Awareness.

This is even an important topic from the perspective of competitive exams which comprise Computer Knowledge as a compulsory subject. Candidates will find all the necessary information well-explained here, along with well-explained notes. 

In this article, we shall discuss in detail the Firewall in a Computer network, along with its functions and its working. The different types of firewalls have also been explained. For the reference of competitive exam aspirants, a few sample questions based on the concept have also be given further below in the article.

A firewall in Computer Network Notes PDF:-Download PDF Here

Links to a few other important computer-related articles have been given below for easy access to detailed information about the following:

What is a Firewall?

A Firewall is a security system to protect an internal network from unauthorized servers and networks based on predefined rules. It acts as a barrier and only allows the secured network to send or receive data. 

How does a Firewall work?

A Firewall analyses the network traffic and filters it so that the unsecured and suspicious networks cannot attack the system. The point where information is exchanged with an external network is called a port. 

How is Firewall different from an Antivirus?

A firewall is a security network designed to protect computer systems and networks from malicious attacks. Whereas, Antivirus is is a software utility program designed to protect a system from internal attacks from viruses. Get a tabulated and detailed comparison between the two at the Difference Between Firewall and Antivirus page. 

With regard to a Firewall, another term that is frequently being used is a Computer Network. To get a detailed explanation and understanding of networking, candidates can visit the linked article. 

Discussed below is a brief account of the evolution and development of Firewall and why it had become an important part of network security.

The term ‘Firewall’ actually meant a wall which intended to confine a fire within a line of adjacent buildings. It was only in the late 1980s when this was acknowledged as a computer terminology. 

It was during this time that the Internet has started to emerge as a new tool for global use. Thus, having a means which could secure the transmission and flow of data was required by many. 

Until the Firewall was introduced, routers performed the same function as it restricted the number of people who could use a particular network. 

For more information regarding the Fundamentals of Computer, visit the linked article. 

There are various types of Firewalls. Described below are each of them in detail for a better and simplistic understanding:

• One of the oldest types of Firewall
• This type of Firewall creates a checkpoint at the traffic router. Only the secure and verified IP address or networks are allowed for the further flow of data
• The data packets are not verified, i.e. the information or data is not opened at the Firewall stage
• They are easy to use and do not overload the device and do not affect its processing or functioning speed

• It is also known as Proxy Firewall
• When the user connects with the destination server, it forms a connection with the application gateway
• The proxy then connects with the destination server and takes up the decision of forwarding the data packets
• It is a bit more secure in comparison to Packet Filtering Firewall
• Strong Memory and processors are required for using this Firewall

• This works as the Sessions layer of the OSI Model
• Using this, two Transmission Control Protocol (TCP) connections can be set up together
• It can easily let the flow of data packets continue without consuming major computer resources
• These Firewalls are not much efficient as they do not check the data packets and incase a data packet comprises malware, it will allow it to pass if the TCP connections are successfully done

• It is a combination of data packet inspection and TCP connection. Until both the fields are verified, the information cannot be approved
• They are less straining for the computer resources
• However, they are a bit slow in comparison to other Firewalls

• The recently launched Firewall systems are known as the Next-Gen Firewalls
• Under this, the data packets are also thoroughly checked before being passed on to the destination address
• These are still on the platform of improving and evolving and intend to use modern technology for automatic detection of errors and network safety

• Any firewall which is installed in a local device or a cloud server is called a Software Firewall
• They can be the most beneficial in terms of restricting the number of networks being connected to a single device and control the in-flow and out-flow of data packets
• Software Firewall also time-consuming

• They are also known as Physical-appliance based firewalls
• It ensures that the malicious data is stopped before it reaches the endpoint of the network at risk

Following are the function of a Firewall. Candidates can refer to these to apprehend the basic functions of a Firewall:

• Any data which enters or exits a computer network has to pass through the Firewall
• All the valuable information stays intact if the data packets are securely passed through the Firewall
• Every time a data packets passed through a Firewall, it records it which allows the user to record the network activity
• No data can be modified as it is held securely within the data packets 

Precisely, a Firewall ensures that all the data is secure and any malicious data trying to enter the internal network is not allowed to pass through.

Computer Knowledge upgrades a person’s awareness of one of the most commonly used devices in today’s world, which is a Computer. 

Questions on Computer Awareness are included in all major competitive exams. In a few, there is a separate section for Computer while some comprise Computer-based questions in General Awareness. In the UPSC exams, they are included in the Science and Technology syllabus. Thus, one must have a sound knowledge of Computer and its functioning.

Given below are sample questions based on Firewall of a computer network. Competitive exam aspirants can refer to these to apprehend the format in which the questions are asked mainly. 

Q 1. Which of these is not a type of Firewall?

1. Next-Generation Firewall
2. Software Firewall
3. Packet Filtering Firewall
4. Switch Firewall
5. Stateful Inspection Firewall

Answer: (4) Switch Firewall

Q 2. Which of the following types of Firewall is also known as ‘Proxy Firewall’?

1. Software Firewall
2. Hardware Firewall
3. Application Level Gateway Firewall
4. Stateful Inspection Firewall
5. Circuit Level Gateway Firewall

Answer: (3) Application Level Gateway Firewall

Q 3. _______ Firewall works as Session layer of the OSI Model.

1. Circuit Level Gateway Firewall
2. Hardware Firewall
3. Software Firewall
4. Stateful Inspection Firewall
5. None of the above

Answer: (1) Circuit Level Gateway Firewall

Q 4. Network layer firewall works as a __________.

1. Virus Filter
2. Packet Filter
3. Malware Filter
4. Data Filter
5. Content Filter

Answer: (2) Packet Filter

A firewall in Computer Network Notes PDF:-Download PDF Here

Candidates looking for study material or tips to prepare, can visit the Preparation Strategy for Competitive Exams page and get the list of major exams along with a structured study plan.

For any further information or exam updates, notes, etc., candidates can turn to BYJU’S for assistance.