How Firewalls Work in Network Security

How Firewalls Work in Network Security

For you to understand a network security system and its working schematics, you must first understand how security vulnerability can threaten a system’s data and network. Imagine your house without a fence or a boundary wall; this will open you up to many vulnerabilities and external threats, which means trespassers and robbers can get access as they deem fit. You can be at risk and robbed of all or almost all your properties.

Similarly, imagine your computer without any security protection like a built-in firewall security system; this will increase the probability of hackers infiltrating your network or other unauthorized administrator accessing your private information.

To overcome this, just as boundary walls protect our houses, a virtual wall can protect our private data from getting into the wrong hands. In networking, this wall is known as a Firewall. Throughout time, firewalls have kept users safe from internet hackers and unauthorized access. We have evidently seen this in network systems and servers around the world.

For us to take a deeper dive into this topic, we need to discuss the types of firewalls and their benefits. We will touch on hosting security, network based firewall, security systems, and more. Keep reading.

What is a Firewall?

A firewall is a system designed to prevent unauthorized administrators or hackers from entering a private network by filtering data assets and information from the internet. A firewall blocks unwanted traffic and permits wanted traffic like a regulatory system.

A full network firewall creates a safety barrier, protecting a private network from the vulnerabilities of the public internet. Hackers and malicious code traffic regularly try the virtual firewall to access the data stored on your private network.

How Does a Firewall Work?

The firewall works like a gatekeeper at your server or computer’s entry point, which only allows incoming traffic it has been configured to accept. Firewalls filter the network traffic within your network and analyzes which traffic should be allowed or restricted based on a set of rules configured to spot cyber attacks.

Your computer communicates with the internet through network packets containing details like the source address, destination address, and information. These network packets enter your computer through ports, and the firewall works on a set of rules based on the details of these three network packets.

The firewall allows only trusted sources or IP addresses to enter your network. For example, IP addresses like will automatically be rejected by the firewall, except if specific permissions are put in place to allow entry.

When you connect your computer to the internet, you are open to hackers and infiltrators looking to access your computer through your PC’s IP address, and this is where the firewall jumps in to save the day. The firewall acts as a barrier between your computer and the internet. The firewall rejects malicious data packets and, on the other hand, allows data packets from trusted source addresses.

Grouping Firewalls

Firewalls can be grouped into either hardware or software. Grouping the firewall helps you understand more about firewalls and give you a better idea of what type of firewall you need for your network security.

Software Firewalls

Software firewalls, or virtual firewalls, are programs installed on a server, also called host-based firewalls.

Hardware Firewalls

Hardware firewalls are equipment or devices established between the perimeter firewall of the gateway and your internal network proxy service firewall. Fortinet routers are a great example of a hardware firewall.

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Types of Firewall

Firewalls are an essential component of network security that help protect computer systems and networks from unauthorized access and malicious activities. Several different types of firewalls are available, each with its characteristics and functionalities. Here are five commonly used different types of firewalls:

Packet Filtering Firewall:

Packet filtering network firewalls operate at the network layer (Layer 3) of the OSI model. They examine individual data packets based on predetermined rules and filters, such as source and destination IP addresses, ports, and protocols. A packet is either allowed or denied access to a network through the firewall if it matches the specified criteria configured with a packet filter. Packet filtering firewalls are generally fast and efficient but lack advanced inspection capabilities.


  • Efficient and fast due to operating at the network layer.
  • Provides essential protection against unauthorized access.
  • Simple configuration and low maintenance requirements.


  • It lacks advanced inspection capabilities, making it vulnerable to certain types of attacks.
  • Limited ability to analyze application-specific traffic.
  • It can be bypassed by attackers using techniques like IP spoofing.

Stateful Inspection Firewall:

Stateful inspection firewalls, also known as dynamic packet filtering firewalls, combine packet filtering features with an awareness of the connection through stateful inspection. They keep track of the state of network connections and allow or block packets based on the context of the entire conversation. This approach improves security by allowing only legitimate or malicious traffic into the network.


  • Offers improved security by considering the context of network connections.
  • It can dynamically allow or deny traffic based on the connection state.
  • Provides better protection against certain types of attacks, such as IP spoofing.


  • It may introduce latency due to maintaining connection state information.
  • Limited ability to inspect application-layer content.
  • May struggle with handling large-scale or complex network environments.

Application Layer and Proxy Firewalls:

Application layer firewalls, also called proxy service firewalls, operate at the application layer (Layer 7) of the OSI model. They act as intermediaries between the client and server, examining the application layer data and making security decisions based on the content, such as HTTP headers or payload. The application layer or proxy firewall provides a detailed inspection and granular control but may introduce additional latency due to the proxying process.


  • Provides detailed inspection and granular control over application-layer traffic.
  • Can detect and block specific application-level threats.
  • Offers strong protection against many types of attacks, including application-specific vulnerabilities.


  • Introduces additional latency due to proxying and deep inspection of application data.
  • Requires specific support and configuration for each application or protocol.
  • They may have compatibility issues with specific applications or protocols.

Next-Generation Firewall (NGFW):

Next-generation firewalls combine traditional firewall functionalities with additional security features, such as intrusion prevention systems (IPS), deep packet inspection (DPI), and application awareness. NGFWs provide enhanced visibility and control over network traffic, allowing administrators to enforce more advanced security rules and policies based on application type, user identity, and content. They often include features like VPN support, full antivirus protection, and web filtering.


  • Combines traditional firewall functionalities with advanced security features.
  • Offers deep packet inspection and application awareness for better threat detection.
  • Provides granular control over network traffic based on application, user, and content.


  • It can be resource-intensive and may require powerful hardware.
  • Complexity in configuration and management due to a wide range of features.
  • Performance impact when enabling advanced security features.

Unified Threat Management (UTM) Firewall:

Unified Threat Management firewalls integrate multiple security features into a single device. In addition to traditional firewall capabilities, UTM firewalls typically include antivirus, anti-spam, web filtering, intrusion detection and prevention, virtual private network (VPN) support, and other security features. UTM firewalls offer a comprehensive security solution, simplifying network security device management by consolidating multiple security functions into one appliance.


  • Integrates multiple security features into a single device, providing comprehensive protection.
  • Simplifies network management and reduces hardware and maintenance costs.
  • Offers a holistic approach to security, including antivirus, web filtering, and intrusion detection.


  • It may have limitations in terms of scalability and performance for more extensive networks.
  • It relies on a single device, potentially creating a single point of failure.
  • Requires regular updates and maintenance to keep all security features up to date.
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How are Firewalls Useful In Network Security?

  1. Access Controls: Firewalls implement access control policies by inspecting network traffic and determining whether it should be allowed or blocked based on specified rules. Firewalls prevent unauthorized network access and limit the flow of potentially dangerous material by screening incoming and outgoing traffic.
  2. Threat Prevention: Firewalls aid in the prevention of numerous threats and assaults from entering the network. They can prevent malicious traffic, such as known malware, viruses, worms, and suspicious network packets, lowering the risk of compromise and infection.
  3. Network segmentation: Is facilitated by firewalls, which divide various network regions into separate security zones. It reduces the effect of a security breach by restricting the lateral movement of hazards within the network.
  4. Traffic Monitoring: Firewalls may monitor network traffic, giving administrators insight into connections and data moving in and out of the network. This monitoring aids in detecting unusual or suspicious actions, allowing for prompt response and mitigation.
  5. App control: Some firewalls include application layer inspection and control, allowing administrators to establish policies based on individual apps or protocols. This helps implement security measures suited to the needs of specific applications, lowering the attack surface and limiting risks.
  6. VPN Support: Many firewalls offer Virtual Private Network (VPN) support, which allows for secure distant network access. VPN connections can be authenticated and encrypted by firewalls, ensuring secure communication between distant users and the internal network.
  7. Logging and Auditing: This process requires the firewalls to frequently include logging and auditing features, providing records of network traffic, rule matches, and security incidents. These logs are helpful for troubleshooting, forensic investigation, compliance, and keeping track of network events.


Using a firewall on your systems today serves as protection against external unauthorized administrators trying to get into your systems. zomev is a Cloud VPS company that offers dedicated server hosting, including hosting security with built-in firewalls to protect you from hackers. We provide unique servers that are well-tailored to meet your needs.

To learn more about server cloud backup that can help store and protect your data from unauthorized administrators, book a free consultation with us. By listening to your requirements, we can configure a firewall specifically for your needs.

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