Firewall - What is, Types, Working and Functions

In today’s digital world, keeping our networks and information safe is crucial. Firewalls help protect our systems from hackers and other threats. In this blog, we will discuss firewalls in detail, including their type, how they work, and their advantages and limitations.

Table of Contents

• What is Firewall?
• History of Firewall
• Types of Firewall
• Working and Function of Firewall
• Why Do We Need a Firewall?
• Advantages and Limitations of Firewall
• Conclusion

What is Firewall?

A firewall is a crucial protective barrier between a computer network and external networks, such as the Internet, guaranteeing robust network security. It actively utilizes pre-established security rules to monitor and diligently regulate incoming and outgoing network traffic. By examining data packets and applying these rules, a firewall proactively strives to eliminate unauthorized access and effectively neutralize potential threats posed by malicious activities.

To accomplish its objectives, a firewall examines the characteristics of data packets, including source and destination IP addresses, ports, protocols, and content. These factors determine whether to permit or block the packets. This approach enables firewalls to effectively manage network traffic and provide defence against potential threats, such as unauthorized access attempts, malware infiltration, and other cyber risks.

Firewalls can be deployed as hardware appliances, software applications, or a combination. They can also be strategically positioned within a network infrastructure, including at the perimeter, between network segments, or on individual devices. This flexibility allows organizations to establish multiple layers of protection and create secure zones within their network architecture.

Moreover, firewalls offer additional security functionalities beyond access control. For instance, Network Address Translation (NAT) allows multiple devices within a network to share a single public IP address, enhancing privacy and network management. Furthermore, firewalls often support Virtual Private Networks (VPNs), enabling secure remote access to the network, bolstering privacy, and ensuring encrypted communication channels.

History of Firewall

The history of firewalls can be traced back to the early days of computer networks and the emergence of the Internet. Here is a summarized history of firewalls, along with the corresponding years:

• 1987: The initial commercial firewall, referred to as the Raptor Firewall, was developed by Digital Equipment Corporation (DEC). This pioneering firewall served as a fundamental packet-filtering firewall solution.
• 1992: Marcus J. Ranum created the Firewall Toolkit, a comprehensive resource that encompasses essential tools and software components for building firewalls.
• 1994: Check Point Software Technologies released FireWall-1, a widely used firewall software that introduced stateful inspection.
• 1995: The Internet Engineering Task Force (IETF) published RFC 1858, the first standard for IP packet filtering firewalls.
• 1998: The development of Network Address Translation (NAT) technology enabled multiple devices in a private network to share a single public IP address, enhancing firewall capabilities.
• 1999: Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) emerged, integrated into firewalls to detect and respond to real-time network attacks.
• 2000: The IETF released RFC 2979, a new standard defining the requirements for firewalls supporting Network Address Translation.
• 2004: Next-generation firewalls (NGFW) were introduced, integrating traditional firewall functionality with additional features such as application awareness, user identification, and content filtering.
• 2010: The rise of cloud computing led to the development of cloud firewalls or virtual firewalls designed to protect virtualized environments and cloud-based applications.
• 2020: The adoption of Software-Defined Networking (SDN) and Software-Defined Firewalls (SDFW) allowed for more flexible and scalable firewall deployments in virtualized and cloud environments.

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Types of Firewall

1. Stateful Firewalls

A “stateful” application in computer science stores information from earlier interactions and occurrences. Instead of analyzing every packet, a stateful firewall stores information about open connections and uses this knowledge to evaluate incoming and outgoing traffic.

Stateful firewalls make decisions by heavily relying on context. For instance, if a connection’s outgoing packets require a specific type of response, the firewall will only permit incoming packets on that connection provided they also include the desired response.

2. Firewall-as-a-service (FWaaS)

The more recent paradigm for providing firewall capabilities through the cloud is firewall-as-a-service (FWaaS). Another name for this service is “cloud firewall.”

 Similar to how conventional firewalls enclose an organization’s internal network, FWaaS creates a virtual wall around cloud platforms, infrastructure, and applications. FWaaS is frequently more effective than traditional firewalls at securing cloud and multi-cloud assets.

3. Web application firewalls (WAF)

WAFs help protect online applications from dangerous users, whereas conventional firewalls protect private networks from harmful web apps. A WAF filters and observes HTTP traffic between a web application and the Internet.

It typically guards against attacks such as cross-site scripting (XSS), file inclusion, SQL injection, and cross-site forgery.  

4. Next-generation firewalls (NGFW)

NGFWs are firewalls that combine traditional firewall functionality with a number of extra features to combat threats at various OSI model layers.

NGFWs examine packets significantly more thoroughly than conventional firewalls. Deep inspection can examine packet payloads and the applications they access, among other things. This enables the firewall to implement filtering rules with greater specificity.

5. Proxy-based firewalls

These intermediaries* between clients and servers are proxies. Clients connect to the firewall, which inspects the outgoing packets before establishing a connection with the target (the web server).

The firewall will also intercept a request from the web server trying to send a response to the client, inspect the packets, and then relay the response through a different connection to the client. Effectively preventing a direct connection between the client and server is a proxy-based firewall.

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Working and Function of Firewall

Now, let’s see how a firewall works and how it will function in our systems.

Working of Firewall

The operation of a firewall centers around its capacity to oversee and manage network traffic based on predefined security rules. Functioning as a safeguarding barrier between a computer network and external networks, such as the Internet, a firewall scrutinizes all incoming and outgoing network traffic, including data packets, determining whether they should be permitted or obstructed.

Firewalls employ security rules that delineate permissible network traffic. These rules typically rely on factors like source and destination IP addresses, port numbers, protocols, and specific content within the data packets. As data packets traverse the firewall, they undergo scrutiny in accordance with these defined rules. The firewall assesses the characteristics of each packet, comparing them against its rule set to determine whether they should be granted passage or blocked.

By enforcing access control policies, firewalls make determinations regarding the allowance or denial of network traffic based on the outcomes of packet inspection. Authorized traffic that conforms to the rules is granted permission, while unauthorized or potentially harmful traffic is impeded.

Firewalls frequently incorporate Network Address Translation (NAT) functionality, enabling multiple devices within a network to share a single public IP address. This NAT feature provides an additional layer of security by concealing the internal network structure.

Logging and auditing play crucial roles in firewall operations. Firewalls maintain logs of the network traffic they process, capturing details such as source and destination IP addresses, ports, protocols, and the actions taken by the firewall (allow or block). These logs are invaluable for troubleshooting, monitoring network activity, and identifying potential security incidents.

Modern firewalls may integrate advanced security features to fortify protection. These features can encompass intrusion detection and prevention systems (IDS/IPS), deep packet inspection (DPI), Virtual Private Network (VPN) support, anti-malware scanning, and application-specific controls.

Firewalls must be continuously monitored and updated to remain effective against emerging threats. This entails keeping the firewall’s software and security rules set up to date and addressing new vulnerabilities and attack patterns.

Functions of Firewall

Here are some key functions of a firewall:

1. VPN Support

Firewalls often provide Virtual Private Network (VPN) support, allowing secure remote access to private networks over the public Internet. They can authenticate and encrypt VPN connections, ensuring that sensitive data transmitted between remote users and the network remains secure.

2. Logging and Auditing

Firewalls generate logs that record information about network traffic, such as source and destination IP addresses, ports, and timestamps. These logs can be used for troubleshooting, forensic analysis, compliance audits, or monitoring network security events.

3. Content Filtering

Some firewalls include content filtering capabilities to control and restrict access to specific types of websites, applications, or content categories. This feature helps organizations enforce acceptable use policies and protect against potential threats or inappropriate content.

4. Bandwidth Management

Firewalls can be configured to manage and allocate network bandwidth resources. They can prioritize certain types of traffic, such as voice or video, over others to ensure optimal performance and prevent network congestion.

5. Denial-of-Service (DoS) Protection

 Firewalls can help mitigate DoS attacks by detecting and blocking excessive or malicious traffic that aims to overwhelm network resources. They can employ various techniques, such as rate limiting, traffic shaping, or packet filtering, to mitigate the impact of such attacks.

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Advantages and Limitations of Firewall

Now that we know what a firewall is and how it works. Let’s look at its various disadvantages and limitations.

Advantages of Firewall

• Firewalls protect computers from viruses, malware, and other destructive codes. Thus, users can carry out their office tasks securely.
• Given that the majority of threats occur through virtual traffic, it is one of the most important benefits of firewalls. Consequently, if you have firewalls installed on your device. If so, it will continue to run in the background and examine all communications.
• Even if you lack technological expertise, you can install firewalls on your computer. Additionally, no expert assistance is required to deploy the firewalls.
• While online, a user expects total privacy, yet certain unforeseen circumstances may make them uncomfortable with this expectation. As a result, if they employ firewalls in that situation, it will ensure that their high level of privacy is maintained.
• Some hackers gain unauthorized access to users’ computers to engage in unlawful activity. They continue to seek devices to break into to steal private information, such as credit card numbers.

Limitations of Firewall

• Firewalls also have several drawbacks for customers, one of which is cost. For businesses, purchasing firewalls can be expensive because they require payment.
• The firewall blocks several websites with viruses or malware. Although this may benefit users, it frequently causes issues for large businesses.
• Firewalls are the security tools that remain active in the computer’s background. Additionally, the computer’s performance will be poor because several tabs are open, and the firewall is on.
• If your machine already has a firewall, you should install anti-virus software to execute the malware detection test and get rid of all these viruses and malware.
• Despite the fact that nowadays, small businesses feel comfortable purchasing firewalls for their computer hardware. However, many large firms require a specialized staff of IT professionals who can handle all firewall maintenance tasks.

Why Do You Need a Firewall?

Networks lacking protection are exposed to any traffic attempting to get into your systems. Network traffic, whether harmful or not, should always be monitored.

A wide range of advantageous opportunities become available when connecting personal computers to other IT systems or the Internet. Facilitating online and security technology can be sacrificed in exchange for uncomplicated collaboration, sharing of resources, and enhanced creativity. Users run the danger of becoming victims of malware, online fraud, identity theft, and hacking if they connect their machines to a network or the internet.

Once a bad actor learns about your network and devices, they can quickly find them, access them, and expose them to ongoing risks. 24/7 internet connectivity increases this risk because your network can be accessed at any time.

Filtering content is another function of firewalls. For instance, a school can set up a firewall to block individuals from accessing adult content on their network. Similar to this, in certain countries, the government maintains a firewall that can bar residents from accessing specific areas of the Internet.

Conclusion

In this blog, you will learn what a firewall is and how it functions as a result of this course. Additionally, you learned about the many kinds of firewalls and how to operate them. Furthermore, we tried to explain the history and the difference between firewall and antivirus. In the modern era, cybersecurity is a booming industry. If you want to learn ethical hacking to defend networks and devices from hackers, then you are in the right place.

Check this video to get a better understanding of firewalls.