Network Kings


$999 $499 only For All Access Pass Today! USE PROMO CODE : LIMITED

d :
h :

What is a Firewall in Computer Network – Explained

What is a Firewall in Computer Network - Explained

In our modern interconnected digital world, the importance of strong cybersecurity measures is undeniable. Among these measures, the firewall plays a vital role as a guardian, shielding our digital assets and sensitive data from malicious threats. But what is a Firewall in Computer Network? Serving as a barrier between our trusted internal networks and the vast, unsecured realm of the internet, firewalls act as our initial defense against cyber attacks.

In this blog, we will delve into the pivotal role of firewalls in securing our digital spaces, grasp their significance, and navigate the evolving landscape of firewall technology in response to the ever-changing cyber threat environment.

What is a Firewall in Computer Network?

A firewall in a computer network acts like a digital bouncer, making sure only the right traffic gets in and out. It is a security guard, either a device or software, that watches over the flow of data, following strict rules to keep the network safe. Its job is to create a protective barrier between the inside of a network, like a company’s servers or computers, and the outside world, such as the Internet. This way, it stops unwanted visitors from sneaking in while still allowing legitimate data to pass through.

These firewalls come in different shapes and sizes, like hardware gadgets or software applications. They work at different layers of how data moves around, depending on what they are designed to do. They check data packets, the digital envelopes carrying information, looking at where they are from, where they are going, and what they are carrying. Then, they decide if they should let them through, block them, or keep a record of what happened.

There are different types of firewalls, each with its special abilities and features. Some are like gatekeepers, inspecting every packet carefully. Others are more like security cameras, watching for suspicious behavior. Together, they form a vital defence line for networks, shielding them from cyber threats and keeping sensitive data safe from harm.

What is the importance of Firewalls in Computer Networks?

The importance of Firewalls in computer networks can be discussed as follows-

  • Security: Firewalls are like digital guards that play a vital role in keeping computer networks safe and secure. They work by stopping unauthorized access and thwarting any sneaky attempts to cause harm or mischief.
  • Access Control: Think of firewalls as the gatekeepers of the network. They decide who gets in and who stays out, making sure only the right kind of traffic is allowed to come and go. This way, they keep the network running smoothly and securely.
  • Protection from Threats: Firewalls act as shields against all sorts of online dangers like viruses, malware, and other nasty stuff that could mess up the network. They’re like the immune system, defending the network from digital infections.
  • Privacy: Firewalls are like digital curtains that keep prying eyes out. They filter and monitor the flow of data, making sure that sensitive information stays safe and doesn’t fall into the wrong hands.
  • Compliance: Firewalls help businesses follow the rules by implementing the necessary security measures to protect data and privacy. It is like having a trustworthy friend who makes sure everything is done by the book.
  • Network Performance: Firewalls are like traffic managers, keeping an eye on the flow of data and making sure everything runs smoothly. They spot potential traffic jams and clear them up, keeping the network moving fast and efficiently.
  • Preventing Unauthorized Access: Firewalls are the security guards of the digital world, keeping unauthorized users out and protecting the network from any unwanted intruders. They are like the locked door that keeps out unwanted guests.
  • Application Control: Firewalls are like digital bouncers at a club, deciding who gets access to specific applications or services. They make sure only the right people get in, enhancing security and productivity.
  • Logging and Auditing: Firewalls keep a digital diary of everything that happens on the network. They record and monitor all activity, helping administrators keep track of what’s going on and detect any suspicious behavior.
  • Risk Mitigation: Firewalls are like digital bodyguards, constantly on the lookout for any potential threats or attacks. They act as the first line of defence, helping organizations stay safe and secure in the digital world.

What is the function of Firewall?

The function of Firewalls can be discussed as follows-

  • Access Control: Firewalls act as traffic managers, deciding which data packets can enter or exit a network based on predefined rules, keeping unauthorized traffic out.
  • Packet Filtering: They examine individual data packets to see if they meet specific criteria, like where they are from and where they are going, before allowing them to pass through or blocking them.
  • Stateful Inspection: Firewalls keep track of the context of active connections, making smarter decisions about whether to allow or block traffic based on the flow of data, adding an extra layer of security.
  • Network Address Translation (NAT): Some firewalls change internal IP addresses to external ones, hiding the structure of the internal network from external sources, and boosting security and privacy.
  • Application Layer Filtering: Firewalls analyze traffic at the application level, giving them the ability to filter based on specific applications or services rather than just basic network information.
  • Proxy Services: Certain firewalls act as go-betweens for clients and servers, intercepting and managing requests and responses to add another layer of security and control.
  • Intrusion Detection and Prevention: Some firewalls are equipped with features to spot and stop suspicious or malicious activity in real time, making networks even more secure.
  • Virtual Private Network (VPN) Support: Firewalls often support VPN connections, allowing secure remote access to the network while keeping transmitted data confidential and intact.
  • Logging and Reporting: Firewalls keep records of network activities and events, giving administrators valuable insights for monitoring, fixing issues, and meeting auditing requirements.
  • Security Policy Enforcement: Firewalls make sure that security policies set by administrators are followed, ensuring that the network complies with organizational security standards and regulations.

What are the different types of Firewalls?

The different types of Firewalls are as follows-

  • Packet Filtering Firewalls

Packet filtering firewalls act as guardians at the gate of your network, inspecting every packet of data that enters or leaves through a network interface. They make decisions on whether to allow or block these packets based on predefined rules.


  1. They offer straightforward and effective basic network security.
  2. Minimal impact on network performance, keeping things running smoothly.
  3. Flexibility to be implemented both at hardware and software levels.
  4. Provide a foundational defense against common network attacks.
  5. Configurable to filter traffic based on IP addresses, ports, and protocols.


  1. Sorting packets based on their source and destination IP addresses.
  2. Evaluating packets according to source and destination ports.
  3. Inspecting packets to discern their protocol types (like TCP or UDP).
  4. Granting or denying traffic based on preset access control lists (ACLs).
  5. Offering basic protection against familiar threats such as port scanning.


  1. Their inspection capabilities are limited to basic header information of packets.
  2. Susceptible to IP spoofing attacks where malicious entities impersonate trusted IP addresses.
  3. Unable to thwart attacks that exploit vulnerabilities in protocols.
  4. Require frequent updates to keep pace with evolving threats.
  5. Managing complex rule sets can become daunting in larger networks.
  • Stateful Inspection Firewalls

Stateful inspection firewalls, also known as dynamic packet filtering firewalls, go beyond mere packet examination. They keep tabs on the state of active connections, making security decisions based on the context of the traffic flow.


  1. Provide a higher level of security by analyzing traffic context.
  2. Enhanced protection against common network attacks.
  3. Ability to track connection states and enforce security policies accordingly.
  4. More resilient against IP spoofing attacks compared to packet filtering firewalls.
  5. Capable of handling more intricate rule sets and policies.


  1. Monitoring the progress of active connections such as the TCP handshake.
  2. Maintaining connection state tables to inform intelligent decisions.
  3. Delving deeper into packet contents beyond basic header information.
  4. Employing session-aware filtering to thwart attacks like Denial of Service (DoS).
  5. Enforcing security policies based on application layer protocols.


  1. Might impose additional overhead on network performance compared to packet filtering.
  2. Vulnerable to certain attacks targeting application layers.
  3. Configuration and maintenance can be complex due to dynamic stateful inspection.
  4. Demands more resources in terms of memory and processing power.
  5. Not foolproof against advanced threats that can evade stateful inspection.
  • Proxy Firewalls

Think of proxy firewalls as gatekeepers with a keen eye for details. They act as intermediaries between internal and external networks, scrutinizing traffic before allowing it to reach its destination. This adds a layer of security by shielding internal network details from external prying eyes.


  1. Enhanced security through thorough inspection and filtering at the application layer.
  2. Conceals internal network specifics, enhancing protection.
  3. Optimizes performance by caching frequently accessed content and reducing bandwidth usage.
  4. Facilitates user authentication and access control for outbound traffic.
  5. Offers robust logging and auditing for effective traffic monitoring.


  1. Serving as a bridge for client requests directed to external servers.
  2. Conducting detailed inspections and filtering at the application layer.
  3. Enhancing performance by caching frequently accessed content.
  4. Validating user identities and enforcing access controls for outbound traffic.
  5. Keeping comprehensive logs for security and compliance purposes.


  1. This may introduce delays due to the meticulous processing involved in each request.
  2. Not universally compatible with all network protocols or applications.
  3. Single point of failure if redundancy measures aren’t in place.
  4. Requires additional configuration for each supported application.
  5. Resource-intensive, especially in high-traffic environments.
  • Next-Generation Firewalls (NGFW)

Next-generation firewalls (NGFW) are the Swiss army knives of network security. They blend traditional firewall functionalities with advanced features like intrusion prevention, application awareness, and deep packet inspection to deliver comprehensive protection.


  1. Employs cutting-edge threat detection and prevention capabilities.
  2. Offers granular visibility and control over network traffic at the application level.
  3. Streamlines security with multiple functions consolidated into a single device.
  4. Supports integration with real-time threat intelligence feeds for proactive protection.
  5. Enables fine-grained policy enforcement based on user, application, and content.


  1. Performs traditional firewall duties such as packet filtering and stateful inspection.
  2. Employs an intrusion prevention system (IPS) to identify and block malicious traffic.
  3. Conducts deep packet inspection to scrutinize packet contents for potential threats.
  4. Recognizes and manages applications with application awareness and control.
  5. Integrates with threat intelligence feeds to detect and mitigate emerging threats.


  1. Tends to be costlier compared to traditional firewalls.
  2. Requires regular updates and maintenance to stay ahead of evolving threats.
  3. Advanced features might impact performance.
  4. Demands additional training for effective configuration and management.
  5. Should be complemented with other security measures like endpoint protection for comprehensive security coverage.
  • Proxy Servers

Proxy servers are the middlemen of the internet world. They stand between clients and servers, handling client requests and routing them to the appropriate servers. Additionally, they offer functionalities like caching, filtering, and anonymity.


  1. Enhances performance by caching frequently requested content, reducing bandwidth consumption.
  2. Strengthens security by filtering and blocking undesirable content.
  3. Provides anonymity to clients by shielding their IP addresses from servers.
  4. Can circumvent network restrictions, granting access to blocked content.
  5. Centralizes control and monitoring of internet traffic.


  1. Routes client requests to servers and relays server responses back to clients.
  2. Boosts performance by caching commonly accessed content.
  3. Filters and blocks undesirable content based on predefined rules.
  4. Preserve client anonymity by concealing their IP addresses.
  5. Enables access to restricted content by bypassing network restrictions.


  1. May introduce latency due to additional processing overhead per request.
  2. Single point of failure if redundancy measures aren’t in place.
  3. May not support all network protocols or applications.
  4. Requires specific configuration for each supported application.
  5. Resource-intensive, especially in high-traffic scenarios.
  • Network Address Translation (NAT) Firewalls

NAT firewalls play hide-and-seek with your network’s internal structure. They translate private IP addresses into public ones and vice versa, keeping internal details concealed from external networks. This not only adds a layer of security but also conserves public IP addresses.


  1. Shields internal network details, beefing up security.
  2. Saves public IP addresses by enabling multiple devices to share one public IP.
  3. Provides a level of protection against certain attacks like IP spoofing.
  4. Facilitates load balancing and traffic management.
  5. Simplifies network setup and management by using private IP addresses internally.


  1. Translating private IP addresses to public IP addresses for outbound traffic.
  2. Converting public IP addresses to private IP addresses for inbound traffic.
  3. Mapping ports to enable communication between internal and external networks.
  4. Managing sessions and maintaining translation tables for active connections.


  1. May introduce complexity in managing and resolving network issues, particularly in larger environments.
  2. Could cause compatibility issues with certain applications or protocols reliant on specific IP addresses or port numbers.
  3. This might impact the performance of real-time applications due to additional processing overhead.
  4. Challenges tracking the origin of traffic for security and auditing purposes.
  5. Vulnerable to specific attacks targeting NAT traversal techniques.

How do Firewalls work?

Firewalls are vital elements of network security, acting as barriers between trusted internal networks and untrusted external ones like the Internet. They use various methods to control and monitor the flow of traffic in and out of the network perimeter, aiming to protect against unauthorized access and potential threats. Let us dive into the key functions of firewalls:

  • Filtering Traffic

  1. Inbound vs. Outbound Traffic: Firewalls handle both inbound (incoming) and outbound (outgoing) traffic to enforce security policies effectively. Inbound traffic refers to data packets entering the internal network from external sources, while outbound traffic is data leaving the internal network for external destinations. Firewalls scrutinize both types of traffic to ensure only authorized communication occurs, preventing malicious entities from entering the network and unauthorized data from leaving.
  2. Rule-Based Filtering: Firewalls use rule-based filtering, where administrators define rules or policies specifying which types of traffic are allowed or denied based on criteria like IP addresses, port numbers, protocols, and application types. For example, a firewall rule may allow incoming HTTP traffic on port 80 but block all other ports. This customization enables organizations to align security policies with their needs and protect against specific threats.
  • Monitoring and Logging

  1. Importance of Logging: Monitoring and logging are crucial for firewall operation, providing visibility into network activities and security incidents. Firewalls log various events such as allowed and denied connections, rule violations, and intrusion attempts. Logging is essential for auditing, compliance, and forensic analysis, enabling administrators to track network behavior, investigate breaches, and identify suspicious activity patterns. Detailed logs aid in proactive threat detection and post-incident analysis.
  2. Analyzing Firewall Logs: Analyzing firewall logs involves reviewing and interpreting logged events to understand network traffic patterns, identify potential threats, and assess the effectiveness of security policies. Administrators can detect anomalies like unusual traffic patterns or repeated failed login attempts, indicating potential malicious activity. Analyzing historical log data helps in identifying trends, evaluating security posture, and refining firewall configurations for enhanced protection.
  • Intrusion Detection and Prevention

  1. Detecting Suspicious Activity: Firewalls play a critical role in intrusion detection by monitoring network traffic for signs of suspicious or unauthorized activity. They inspect packets in real time for indicators of known attack signatures, abnormal behavior, or deviations from norms. Intrusion detection mechanisms within firewalls can detect threats such as port scans, malware, DoS attacks, and intrusion attempts targeting vulnerable services.
  2. Preventing Intrusions: Firewalls can employ intrusion prevention capabilities to actively block or mitigate identified threats in real time. Integrated intrusion prevention systems (IPS) automatically respond to detected threats by blocking malicious traffic, terminating suspicious connections, or triggering proactive security measures. By combining detection and prevention capabilities, firewalls actively defend against emerging threats and minimize the risk of successful intrusions.

What are the best practices for Firewall Configuration?

The best practices for Firewall Configuration are as follows-

  • Rule Management

  1. Creating Effective Rules: When we make rules for our firewall, we need to be crystal clear about what we want it to allow or block. These rules should be straightforward, not too long, and in line with our organization’s security policies. We think about stuff like where the traffic is coming from and going to, what protocols and ports are okay, and which applications or services are allowed. It is all about finding the right balance between keeping things safe and letting the good stuff through.
  2. Rule Prioritization: It is like organizing your closet – you want the important stuff up front. With firewalls, we need to make sure the rules are in the right order so they work the way we want them to. We organize them based on what’s most important for our network. We give priority to rules that enforce our top security policies and access controls. And if there is a conflict between rules, we make sure the more specific ones take precedence. We check and adjust these priorities regularly to keep things running smoothly.
  • Regular Updates and Maintenance

  1. Importance of Updates: Just like our phones need updates to stay secure, firewalls do too. We need to keep them up-to-date with the latest security fixes and info on new threats. New vulnerabilities and risks pop up all the time, so updating our firewall helps it stay strong against evolving dangers. And don’t forget about firmware updates for the hardware – they keep everything running smoothly and playing nice with the rest of the network.
  2. Scheduled Maintenance Tasks: Think of this as giving your car a regular check-up. We need to do things like backing up our firewall settings, checking our rules and policies, and tuning up performance based on how our network traffic is flowing. It is also a good idea to run security checks and tests to find any weak spots that need fixing. These regular tasks keep our firewall healthy and ready to protect us.
  • Network Segmentation

  1. Segregating Networks for Enhanced Security: This is like dividing your house into different rooms – it helps keep things organized and safe. With network segmentation, we split up our network into different zones or segments to control how traffic moves around. Using firewalls to separate these zones means we can tighten up access controls and keep sensitive stuff away from less secure areas. If something goes wrong, segmenting the network helps contain the problem and stop it from spreading.
  2. Implementing Segmentation with Firewalls: Firewalls are like the bouncers at the doors between these network zones. We set up rules in our firewalls to decide who gets to go where. By using firewalls for segmentation, we can be really picky about who’s allowed in and who’s not. We keep a close eye on the traffic between segments, and if anyone tries to sneak into a place they shouldn’t, the firewall steps in and says, “Sorry, not today!”

What are the challenges of using a Firewall?

The challenges of using a Firewall are listed as follows-

  • Complex Configuration: Setting up a firewall can get pretty complicated, especially if we are not tech-savvy. It involves understanding things like network protocols, ports, and what our organization needs to stay secure.
  • Rule Management: Keeping track of all the rules in our firewall can be a hassle, especially in big networks. Over time, the rules can pile up and get messy, leading to confusion and potential security problems if we don’t keep them organized.
  • False Positives: Sometimes our firewall might mistake normal traffic for something harmful and block it by mistake. This can mess up our regular activities and annoy our users.
  • Resource Intensive: Firewalls can hog a lot of resources, especially if they’re doing fancy stuff like deep packet inspection. This can slow down our network and make us need more hardware to keep things running smoothly.
  • Complex Network Environments: When we have lots of devices and different parts of our network to look after, keeping our firewall rules consistent across everything can be tricky.
  • Evading Detection: Sneaky attackers might find ways to get past our firewall, like using encrypted traffic or finding holes in the firewall’s software.
  • Lack of Granularity: Some firewalls don’t give us enough control over who can access what, making it hard to set up specific security rules for different users or applications.
  • Compatibility Issues: Sometimes our firewall doesn’t get along with certain programs or ways of doing things, which can cause problems or mean we have to fiddle around with settings.
  • Management Overhead: If we have loads of firewalls spread out across different parts of our network, keeping them all in line can be a real drain on time and resources. We need dedicated folks and tools to keep everything running smoothly.
  • Continuous Monitoring: Our firewall needs constant attention to make sure it is doing its job right. This means keeping an eye on the logs for any security issues, updating the rules to deal with new threats, and regularly checking everything to make sure it is all still secure.

What is the future of Network Security using Firewall Technology?

The future of Firewalls can be observed via the given points-

  • Next-Generation Firewalls

Next-generation firewalls (NGFWs) are advancing to tackle modern cybersecurity threats effectively. Unlike traditional firewalls, NGFWs incorporate advanced features such as intrusion prevention, application awareness, and deep packet inspection. By analyzing traffic at the application layer and applying granular security policies based on user, application, and content, NGFWs can identify and thwart sophisticated threats. Additionally, they often integrate threat intelligence feeds and machine learning capabilities to enhance threat detection and response.

NGFWs are integrating with various security tools and platforms to form a unified security ecosystem. Integration with Security Information and Event Management (SIEM) systems enables centralized logging and analysis of firewall data, improving visibility into network activities and security events. Moreover, integration with threat intelligence platforms empowers NGFWs to utilize up-to-date threat intelligence feeds for proactive threat detection and response, bolstering their effectiveness against diverse cyber threats.

  • Cloud-Based Firewalls

Cloud-based firewalls offer several advantages over traditional on-premises solutions. They provide scalability and flexibility, allowing organizations to adjust firewall resources based on demand without additional hardware investment. Simplified management and centralized control are other benefits, enabling administrators to manage firewall policies and configurations across distributed environments from a single dashboard. Furthermore, cloud-based firewalls leverage cloud infrastructure redundancy and failover mechanisms, enhancing resilience and availability.

While cloud-based firewalls offer numerous benefits, organizations must consider certain factors. Ensuring compliance requirements and adequate security controls for protecting sensitive data in the cloud is essential. Evaluation of factors such as latency, data residency, and bandwidth requirements is necessary to ensure optimal performance and user experience. Additionally, organizations should consider the cost implications, including subscription fees, data transfer costs, and potential integration expenses with other cloud services. By carefully considering these factors, organizations can maximize the benefits of cloud-based firewalls while addressing potential challenges and maintaining effective security in the cloud environment.

Where can I get the best Firewall training?

To learn the best Firewall courses, you can choose Network Kings. Being one of the best ed-tech platforms, you will get to enjoy the following perks-

  • Learn directly from expert engineers
  • 24*7 lab access
  • Pre-recorded sessions
  • Live doubt-clearance sessions
  • Completion certificate
  • Flexible learning hours
  • And much more.

NOTE: Enroll in our Super Firewall Master Program comprising Palo Alto Firewall, CheckPoint Firewall, and F5 LTM programs. 

What are the job opportunities for a Firewall certified?

The top available job opportunities for a Firewall certified are as follows-

  • Network Security Engineer
  • Information Security Analyst
  • Security Operations Center (SOC) Analyst
  • Firewall Administrator
  • Cyber Security Consultant
  • Network Security Administrator
  • Penetration Tester
  • Security Consultant
  • Network Security Specialist
  • IT Security Engineer
  • Security Architect
  • Network Administrator
  • Systems Administrator
  • IT Manager
  • Cyber Security Manager
  • Chief Information Security Officer (CISO)
  • Security Analyst
  • Information Security Manager
  • Incident Response Analyst
  • Security Auditor

What are the salary aspects for a Firewall certified in IT?

The salary aspects for a Firewall certified in IT are as follows-

  • United States: USD 87,370 – USD 126,700 per year
  • Canada: CAD 61,000 – CAD 107,000 per year
  • United Kingdom: GBP 29,000 – GBP 65,000 per year
  • Germany: EUR 40,000 – EUR 70,000 per year
  • France: EUR 36,000 – EUR 55,000 per year
  • Switzerland: CHF 85,000 – CHF 140,000 per year
  • Australia: AUD 60,000 – AUD 120,000 per year
  • New Zealand: NZD 55,000 – NZD 90,000 per year
  • Japan: JPY 4,500,000 – JPY 7,500,000 per year
  • Singapore: SGD 35,000 – SGD 100,000 per year
  • India: INR 300,000 – INR 1,500,000 per year
  • China: CNY 100,000 – CNY 300,000 per year
  • Brazil: BRL 50,000 – BRL 120,000 per year
  • South Africa: ZAR 180,000 – ZAR 500,000 per year
  • United Arab Emirates: AED 120,000 – AED 360,000 per year

Wrapping Up!

Grab this chance to upgrade and become a top-notch Firewall engineer expert today. If you are looking to learn the prominent Firewall engineer skills, consider enrolling in our Super Firewall Master Program today. Should you have any questions or require assistance, please do not hesitate to reach out to us through the comment section. Your queries are welcome, and we are here to help!

Happy Learning!