Firewall In Computer Network

firewall is a hardware or software-based network security device that monitors all incoming and outgoing traffic and accepts, rejects, or drops that traffic based on a defined set of security rules.

This computer network creates a barrier between secure internal networks and untrusted networks like the Internet.


This computer network is analogous to a sentry stationed outside the home of an important person (such as the president of India). This sentry generally keeps an eye on and physically checks everyone who comes and goes from the house.

If the sentry suspects that a person attempting to enter the president’s residence is carrying a knife, the person will be denied entry.

Similarly, the sentry may still refuse entry even if a person does not possess any prohibited items but appears suspicious.

What is a firewall?

How does a firewall work?

The firewall acts as a gatekeeper for your network, and it does so in two basic ways.

1. Packet Filtering:

Think of it like a bouncer checking everyone’s ID at the entrance of the club. Every data packet attempting to enter or leave your network is examined based on specific criteria set by your computer network rules.

These parameters may include source and destination IP addresses, port numbers, and type of data protocol. Packets that meet the criteria are allowed, while others are rejected.

2. Stateful Inspection:

It’s like a bouncer who is not only checking your ID but also remembering who you are during your stay in the club. In a network context, stateful inspection monitors the state of active connections.

This ensures that incoming data packets are valid responses to outgoing requests, thereby increasing security.

Importance of Firewall

Why are firewalls so important in today’s digital landscape?

1. Protection from cyber threats:

This computer network is your first line of defense against a wide range of cyber threats, including malware, viruses, and hacking attempts. They prevent malicious actors from gaining unauthorized access to your network.

2. Privacy and Data Security:

This computer network helps protect your personal and sensitive information. They ensure that your data remains within the scope of your network, protecting it from prying eyes.

3. Control and Access Management:

This computer network gives you control over what goes in and out of your network. You can set rules and policies to manage access, which is especially important in corporate and organizational settings.

4. Compliance and Regulations:

Many industries and organizations are subject to specific regulations regarding data security and privacy. this computer network helps you comply with these regulations, avoiding legal issues and data breaches.

History of Firewall

The term “firewall” actually refers to a structure designed to contain fire to adjacent structures. It wasn’t until the 1980s that firewalls were recognized as computer terminology.

Network This computer network was developed to combat security threats. this computer network will continue to be important in organizations and society.

So, let’s look at the history of this computer network.


In 1993, Gil Schwed of Check Point Technologies introduced the first checkpoint firewall in the country. It was known as FireWall-1. NetScreen introduced its purpose-built computer network ‘Appliance’ in 2000.

It has rapidly gained popularity and adoption in the industry due to high internet speeds, low latency, and high throughput cost-effectiveness


A new type of computer network was introduced at the turn of the century in mid-2010. Palo Alto Networks introduced a “next generation firewall” These firewalls have built-in functionality and capabilities, such as hybrid cloud support, network threat prevention, application, and identity-based control, scalable performance, etc. When it comes to network security, they are considered the first line of defense.


The organization’s Internet connection is not an option. However, the organization benefits from the use of the Internet. It also provides a link between the outside world and the internal organizational network.

This poses a risk to the organization. This computer network is required to protect the internal network from unauthorized traffic.


Generation of Firewalls Networks


A packet-filtering computer network controls network access by monitoring outgoing and incoming packets and enabling interception or blocking based on source and destination IP addresses, protocols, and ports This requires data at the transport protocol layer (however it primarily uses the first three layers).

These packet filters have no way of knowing if the packet is part of an existing traffic flow. but reserves the right to allow or deny packets based on unique packet headers.


Second generation: Stateful monitoring firewall


Stateful this computer network can determine the communication state of a packet, making it more efficient than packet-filtering this computer network.

It monitors the status of TCP streams and other network connections passing through it. The filtering decisions will be based not only on the defined rules but also on the packet history of the state table.

Third generation: Application layer firewall

Each OSI(Open System Interconnected) layer, up to the application layer, can be monitored and configured by the application layer firewall. It can detect when certain applications and protocols (such as HTTP and FTP) are being abused by blocking specific features.


The next-generation firewall


This firewall has been used to prevent modern security breaches such as advanced malware attacks and application-layer attacks. Application monitoring, deep packet monitoring, SSL/SSH monitoring, and other features protect the network against modern threats. Next-generation firewalls examine packets at the application layer of the TCP/IP stack and can detect and enforce security policies, such as Skype or Facebook, based on the type of application


Types of Firewalls in Computer Networks


There are several types of firewalls used in computer networks, each with its own characteristics and deployment scenarios. Here are some common types:


  1. Packet Filtering Firewall:
    • Packet filtering firewalls operate at the network layer (Layer 3) of the OSI model.
    • They examine the header information of each packet and compare it against a set of predefined rules or access control lists (ACLs).
    • Based on these rules, packets are allowed or blocked.
    • Packet filtering firewalls are typically fast and efficient but lack advanced inspection capabilities.
  2. Stateful Inspection Firewall:
    • Stateful inspection firewalls, also known as stateful computer networks, combine packet filtering with the ability to maintain information about the state of network connections.
    • They keep track of the state, context, and history of each connection, allowing them to make more intelligent decisions about which packets to allow or block.
    • Stateful inspection of this computer network provides improved security compared to packet filtering firewalls by considering the context of network traffic.
  3. Application Layer Firewall:
    • Application layer this computer network, also known as a proxy computer network or application gateway, operates at the application layer (Layer 7) of the OSI model.
    • This computer network provides deep inspection of application-layer protocols, analyzing the content of the data packets to make more informed decisions.
    • They can filter traffic based on specific application protocols, such as HTTP, FTP, or SMTP.
    • The application layer of this computer network offers advanced security features but may introduce additional latency due to the deep packet inspection process.
  4. Next-Generation Firewall (NGFW):
    • Next-generation this computer network (NGFW) combines the capabilities of traditional firewalls with additional features like deep packet inspection, intrusion prevention systems (IPS), application awareness, and user identification.
    • NGFWs provide granular control over network traffic, allowing administrators to create policies based on application usage, user identity, and content.
    • They offer enhanced visibility into network activity and advanced threat detection capabilities.
  5. Proxy Firewall:
    • Proxy This computer network acts as an intermediary between clients and servers, establishing a separate connection for each request.
    • They receive network traffic on behalf of clients and forward the requests to the destination after inspecting and filtering the packets.
    • Proxy this computer network can provide additional security by hiding the internal network’s details and applying strict access controls.
  6. Virtual Private Network (VPN) Firewall:
    • VPN This computer network combines firewall functionality with Virtual Private Network (VPN) capabilities.
    • They allow secure remote access to private networks over the internet by encrypting and authenticating network traffic.
    • VPNs this computer network provides secure connectivity for remote users or branch offices, preventing unauthorized access to sensitive data.
  7. Cloud Firewall:
    • Cloud firewalls are specifically designed for cloud environments and provide security for virtualized infrastructure and cloud-based applications.
    • They protect cloud resources by enforcing access controls, monitoring network traffic, and detecting and blocking malicious activities.
    • Cloud firewalls are highly scalable, and flexible, and often integrate with cloud service providers’ management interfaces.

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