Firewall in Computer Network

Last Updated on April 13, 2023 by Prepbytes

Nowadays, protecting our sensitive data from unwanted and unauthorized sources is a significant challenge. There are various tools and devices that can provide varying levels of security and help keep our private data safe. A ‘firewall’ is one such tool that prevents unauthorized access and keeps our computers and data safe and secure.

What is the Firewall in Computer Network?

A firewall is a software or hardware device that provides security to computer networks by controlling incoming and outgoing traffic. It is designed to block unauthorized access while allowing authorized traffic to pass. A firewall is like a security guard that sits at the entrance of a network and checks who are trying to enter and what they are trying to do. It examines the data packets that are sent and received on a network and decides whether to allow or deny them based on a set of predetermined rules.

A firewall’s primary function is to allow non-threatening traffic while blocking malicious or unwanted data traffic in order to protect the computer from viruses and attacks. A firewall is a cybersecurity tool that filters network traffic and assists users in preventing malicious software from connecting to the Internet on infected computers.

Working of Firewall in Computer Network

A firewall system examines network traffic in accordance with predefined rules. It then filters the traffic and prevents it from coming from untrustworthy or suspicious sources. It only accepts incoming traffic that has been configured to accept it.

Firewalls typically intercept network traffic at a computer’s entry point, referred to as a port. Firewalls accomplish this by allowing or blocking specific data packets (communication units transferred over a digital network) based on pre-defined security rules. Incoming traffic is only permitted from trusted IP addresses or sources.

The working of a firewall can be explained in the following steps:

Identification of the Data Packets
The first step in the working of a firewall is the identification of the data packets. When a data packet is sent or received on a network, the firewall examines the packet to determine its source, destination, protocol, and other information.

Comparison with Predefined Rules
After identifying the data packet, the firewall compares it against a set of predefined rules. These rules can be based on the type of traffic, the source of the traffic, the destination of the traffic, or the content of the traffic.

Allow or Block Decision
Based on the predefined rules, the firewall decides whether to allow or block the data packet. If the data packet matches the rule, it is allowed to pass, and if it does not match the rule, it is blocked.

Logging and Alerting
If a data packet is blocked by the firewall, the firewall can log the event and alert the network administrator. This allows the administrator to investigate the event and take appropriate action.

Firewall in computer network can be configured to block incoming traffic, outgoing traffic, or both. They can also be configured to allow traffic from specific IP addresses or to specific ports. Firewalls can also be configured to block traffic based on the protocol being used.

Types of Firewall in Computer Network

Here we have some common types of firewall in computer network

• Packet-Filtering Firewalls
  Packet-filtering firewalls are one of the oldest and most basic types of firewalls. They operate at the network layer (Layer 3) of the OSI model, examining each incoming or outgoing packet and comparing it to a set of predefined rules. These rules can specify the IP address, port number, protocol, or other attributes of the packet. If the packet matches the rules, it is allowed through; if not, it is blocked.

  Packet-filtering firewalls are relatively simple and efficient, but they have some limitations. They can be vulnerable to IP spoofing attacks, in which an attacker sends packets with fake source addresses to bypass the firewall. They also cannot inspect the contents of packets beyond the header information.

• Stateful Multi-layer Inspection (SMLI) Firewall
  Stateful Multi-layer Inspection (SMLI) firewalls are more advanced than packet-filtering firewalls. They operate at the transport layer (Layer 4) of the OSI model and keep track of the state of network connections. This allows them to distinguish legitimate traffic from malicious traffic and detect and block attacks such as port scanning and denial-of-service (DoS) attacks.

  SMLI firewalls can also inspect packet contents beyond the header information, using deep packet inspection (DPI) techniques to analyze application-layer data. This makes them more effective at detecting and blocking malware and other threats.

• Proxy Firewall
  Proxy firewalls operate at the application layer (Layer 7) of the OSI model, acting as intermediaries between clients and servers. They intercept all traffic between the client and server, examining it and filtering out any malicious or unauthorized traffic.

  Proxy firewalls can provide additional security benefits, such as hiding the IP address and other identifying information of the client from the server. They can also perform content filtering to block access to certain websites or restrict the use of certain applications.

• Network Address Translation (NAT) Firewalls
  Network Address Translation (NAT) firewalls are a type of firewall that uses NAT to map multiple private IP addresses to a single public IP address. This provides a level of security by hiding private IP addresses from the public internet.

  NAT firewalls are commonly used in small business and home networks, but they have some limitations. They cannot inspect the contents of packets beyond the header information, and they do not provide protection against many types of attacks.

• Unified Threat Management (UTM) Firewall
  Unified Threat Management (UTM) firewalls are a type of firewall that combines multiple security features in a single device. UTM firewalls typically include features such as antivirus, antispam, content filtering, intrusion detection and prevention, and virtual private network (VPN) capabilities.

  UTM firewalls are designed to provide comprehensive security for small and medium-sized businesses, which may not have the resources to implement and manage multiple security devices. They can provide a high level of security and convenience, but they can also be complex to configure and maintain.

• Next-Generation Firewall (NGFW)
  Next-Generation Firewall (NGFW) is a type of firewall that combines traditional firewall capabilities with advanced security features such as application awareness, intrusion prevention, and sandboxing. NGFWs use DPI to inspect and analyze packet contents, allowing them to identify and block sophisticated threats such as advanced persistent threats (APTs).

Advantages of Firewall in Computer Network

Here we have some common advantages of firewall in computer networks

• Protection against External Threats: Firewalls provide a layer of protection between a network and the external environment, such as the Internet. They prevent unauthorized access to the network, blocking any attempts by hackers or malicious software to infiltrate and compromise the system.
• Control over Network Traffic: Firewalls allow administrators to control and monitor network traffic, enabling them to identify and block unauthorized traffic and access. They can also enforce policies regarding acceptable network usage, preventing users from accessing certain websites or applications that may pose a security risk.
• Improved Network Performance: Firewalls can help to improve network performance by filtering out unnecessary traffic, such as spam emails or unwanted network requests. This reduces the amount of bandwidth consumed by non-essential traffic, freeing up resources for legitimate network activities.
• Compliance with Security Standards: Many industries have specific security standards that must be met to ensure compliance with regulations and protect sensitive data. Firewalls can help organizations meet these standards by providing a layer of security that can be audited and monitored.
• Scalability: Firewalls can be scaled up or down to meet the needs of different organizations. Small businesses can use simple firewalls with basic functionality, while larger organizations can use more advanced firewalls with multiple layers of security.

Disadvantages of Firewall in Computer Network

Here we have some disadvantages of firewall in computer network

• False Sense of Security: While firewalls provide a valuable layer of protection, they can also give users a false sense of security. Administrators may assume that their network is fully protected by a firewall, leading to complacency and a failure to implement other security measures.
• Cost: Implementing a firewall can be costly, especially for small businesses or organizations with limited resources. Advanced firewalls with multiple layers of security can be expensive to purchase, configure, and maintain.
• Complexity: Firewalls can be complex to configure and manage, requiring skilled IT staff to implement and maintain. This can be a challenge for smaller organizations that may not have the resources or expertise to manage a firewall effectively.
• Limitations: Firewall in computer network have some limitations in terms of their ability to detect and block advanced threats, such as zero-day exploits or targeted attacks. While they can provide a valuable layer of protection, they are not a silver bullet solution to all security threats.

Applications of Firewall in Computer Network

Here we have some common applications of firewall in computer network

• Network Security: Firewalls are primarily used to enhance network security by preventing unauthorized access to a network. They can block incoming traffic from known malicious sources and prevent outgoing traffic from infected devices.
• Content Filtering: Firewalls can be used to block access to certain websites or restrict the use of certain applications on a network. This can be useful in preventing users from accessing malicious or inappropriate content.
• Remote Access: Firewalls can be used to provide secure remote access to a network, allowing users to access network resources from outside the organization. This is often done using a VPN, which provides a secure tunnel for data to travel through.
• Compliance: Firewalls can help organizations meet regulatory requirements by providing a layer of security that can be audited and monitored. Many industries have specific security standards that must be met to ensure compliance with regulations and protect sensitive data.
• Network Performance: Firewalls can help to improve network performance by filtering out unnecessary traffic, such as spam emails or unwanted network requests. This reduces the amount of bandwidth consumed by non-essential traffic, freeing up resources for legitimate network activities.

Conclusion
Firewall in computer network is a security mechanism that monitors and controls incoming and outgoing network traffic. There are several types of firewalls, including proxy firewalls, packet-filtering firewalls, stateful multi-layer inspection firewalls, unified threat management firewalls, next-generation firewalls, and network address translation firewalls. Firewalls offer several advantages, including protection against external threats, control over network traffic, improved network performance, compliance with security standards, and scalability. However, they also have disadvantages, such as a false sense of security, cost, complexity, and limitations in detecting and blocking advanced threats.

Applications of firewalls include network security, content filtering, remote access, compliance, and network performance. Firewalls play a crucial role in network security and are essential for protecting sensitive data and complying with security regulations.

Frequently Asked Questions

Here we have FAQs on the firewall in computer network

Q1. What are the challenges of implementing and managing a firewall?
Ans. Firewall in computer network can be complex to configure and manage, requiring skilled IT staff to implement and maintain. This can be a challenge for smaller organizations that may not have the resources or expertise to manage a firewall effectively. Firewalls can also be costly to purchase, configure, and maintain, which can be a barrier for organizations with limited resources.

Q2. Can a firewall impact network performance?
Ans. Yes, a firewall can impact network performance, depending on how it is configured and the volume of traffic passing through it. Some firewalls may add latency or reduce network throughput, which can impact network performance.

Q3. How can I test my firewall to ensure it is working correctly?
Ans. There are various ways to test a firewall, including vulnerability scanning, penetration testing, and network traffic analysis. You can also use tools such as port scanners and packet sniffers to test your firewall’s effectiveness in blocking or allowing traffic.

Q4. Should I use a hardware or software firewall?
Ans. Both hardware and software firewalls have their benefits and drawbacks. Hardware firewalls are typically more expensive but can offer better performance and scalability for larger networks. Software firewalls, on the other hand, are less expensive and can be installed on individual devices for more granular control over network traffic.

Q5. Can a firewall prevent social engineering attacks?
Ans. No, a firewall cannot prevent social engineering attacks. Social engineering attacks rely on manipulating human behavior rather than exploiting technical vulnerabilities. Preventing social engineering attacks requires a combination of employee education, security awareness training, and policies and procedures to prevent unauthorized access to sensitive information.

Q6. What are some common mistakes to avoid when configuring a firewall?
Ans. Common mistakes when configuring a firewall include misconfiguring rules, leaving unnecessary ports open, failing to update firewall software and firmware, and not testing the firewall thoroughly before deploying it. It is important to carefully plan and configure your firewall to avoid these mistakes and ensure optimal security.