Firewall
What Is Firewall?
Firewall is a network security device that observes and filters incoming and outgoing network traffic, adhering to the security policies defined by an organization. Essentially, it acts as a protective wall between a private internal network and the public Internet.
Fencing your property protects your house and keeps trespassers at bay; similarly, firewalls are used to secure a computer network. Firewalls are network security systems that prevent unauthorized access to a network. It can be a hardware or software unit that filters the incoming and outgoing traffic within a private network, according to a set of rules to spot and prevent cyberattacks.
Firewalls are used in enterprise and personal settings. They are a vital component of network security. Most operating systems have a basic built-in firewall. However, using a third-party firewall application provides better protection.
Now that we have understood what is firewall, moving forward we will see the history of firewalls.
Types of Firewalls
A firewall can either be software or hardware. Software firewalls are programs installed on each computer, and they regulate network traffic through applications and port numbers. Meanwhile, hardware firewalls are the equipment established between the gateway and your network. Additionally, you call a firewall delivered by a cloud solution as a cloud firewall.
There are multiple types of firewalls based on their traffic filtering methods, structure, and functionality. A few of the types of firewalls are:
A packet filtering firewall controls data flow to and from a network. It allows or blocks the data transfer based on the packet's source address, the destination address of the packet, the application protocols to transfer the data, and so on.
This type of firewall protects the network by filtering messages at the application layer. For a specific application, a proxy firewall serves as the gateway from one network to another.
Such a firewall permits or blocks network traffic based on state, port, and protocol. Here, it decides filtering based on administrator-defined rules and context.
According to Gartner, Inc.’s definition, the next-generation firewall is a deep-packet inspection firewall that adds application-level inspection, intrusion prevention, and information from outside the firewall to go beyond port/protocol inspection and blocking.
A UTM device generally integrates the capabilities of a stateful inspection firewall, intrusion prevention, and antivirus in a loosely linked manner. It may include additional services and, in many cases, cloud management. UTMs are designed to be simple and easy to use.
These firewalls provide advanced threat detection and mitigation. With network and endpoint event correlation, they may detect evasive or suspicious behavior.
How Does a Firewall Work?
As mentioned previously, firewalls filter the network traffic within a private network. It analyses which traffic should be allowed or restricted based on a set of rules. Think of the firewall like a gatekeeper at your computer’s entry point which only allows trusted sources, or IP addresses, to enter your network.
A firewall welcomes only those incoming traffic that has been configured to accept. It distinguishes between good and malicious traffic and either allows or blocks specific data packets on pre-established security rules.
These rules are based on several aspects indicated by the packet data, like their source, destination, content, and so on. They block traffic coming from suspicious sources to prevent cyberattacks.
For example, the image depicted below shows how a firewall allows good traffic to pass to the user’s private network.
Fig: Firewall allowing Good Traffic
However, in the example below, the firewall blocks malicious traffic from entering the private network, thereby protecting the user’s network from being susceptible to a cyberattack.
Fig: Firewall blocking Bad Traffic
This way, a firewall carries out quick assessments to detect malware and other suspicious activities.
There are different types of firewalls to read data packets at different network levels. Now, you will move on to the next section of this tutorial and understand the different types of firewalls.
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Why Are Firewalls Important?
Firewalls are designed with modern security techniques that are used in a wide range of applications. In the early days of the internet, networks needed to be built with new security techniques, especially in the client-server model, a central architecture of modern computing. That's where firewalls have started to build the security for networks with varying complexities. Firewalls are known to inspect traffic and mitigate threats to the devices.
Key Uses of Firewalls
Functions of Firewall
Advantages of Using Firewalls
Now that you have understood the types of firewalls, let us look at the advantages of using firewalls.
How to Use Firewall Protection?
To keep your network and devices safe, make sure your firewall is set up and maintained correctly. Here are some tips to help you improve your firewall security:
Application Layer and Proxy Firewalls
Proxy firewalls can protect the application layer by filtering and examining the payload of a packet to distinguish valid requests from malicious code disguised as valid requests for data. Proxy firewalls prevent attacks against web servers from becoming more common at the application layer. Besides, proxy firewalls give security engineers more control over network traffic with a granular approach.
On the other hand, application layer filtering by proxy firewalls enables us to block malware, and recognize the misused amongst various protocols such as Hypertext Transfer Protocol(HTTP), File Transfer Protocol (FTP), certain applications, and domain name system(DNS).
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Next Generation Firewalls (NGFW)
Next-Generation Firewalls are used to inspect packets at the application level of the TCP/IP stack, enabling them to identify applications such as Skype, or Facebook and enforce security policies concerning the type of application. Next-Generation Firewalls also include sandboxing technologies, and threat prevention technologies such as intrusion prevention systems (IPS), or antivirus to detect and prevent malware and threats in the files.
Vulnerabilities
Insider attacks involve activities such as the transmission of sensitive data in plain text, resource access outside of business hours, sensitive resource access failure by the user, third-party users' network resource access, etc.
Distributed denial of service (DDoS) attack is a malicious attempt to disrupt normal traffic of a targeted network by overwhelming the target or its surrounding infrastructure with a flood of traffic. The DDoS attack is used to mitigate the difference between an attack and normal traffic. Nevertheless, the traffic in this attack type can come from seemingly legitimate sources that require cross-checking and auditing from several security components.
Malware threats are usually difficult due to their varied, complex, and constantly evolving nature. These days, with the rise of IoT, networks are becoming more complex and dynamic so that sometimes it becomes difficult for firewalls to defend against malware.
Patching/Configuration is a firewall with a poor configuration or a missed update from the vendor that may damage network security. Thus, IT admins need to be very proactive concerning their maintenance of security components.
The Future of Network Security
In the last few years, virtualization and trends in converged infrastructure created more east-west traffic and the largest volume of traffic in a data center is moving from server to server. Some enterprise organizations have migrated from the traditional three-layer data center architectures to various forms of leaf-spine architectures in order to with this change. This change in architecture made some security experts warn that firewalls have an important role to play to keep the network secure in a risk-free environment. Thus, the importance and future of firewalls have no end. However, there may be many advanced alternatives to firewalls in the future.
Difference Between a Firewall and Antivirus
Firewall
Antivirus
Limitations of a Firewall
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Conclusion
In this tutorial on what is a firewall, you have understood what a firewall is and how it works. You also learned the different types of firewalls and how to use a firewall. Cybersecurity is a booming field in today's times. If you are looking to learn ethical hacking to protect devices and networks from cybercriminals. In that case, Simplilearn's Cyber bootcamp, CEH v11 - Certified Ethical Hacking Course will help you master advanced network packet analysis and penetration testing techniques to build your network security skill-set.
Do you have any questions on this tutorial on ‘what is a firewall’? If you do, please drop them in the comments section. We will help you solve your queries at the earliest.
FAQs
1. What is a computer firewall?
A computer firewall is a security system, which can be either hardware or software-based. It monitors and controls incoming and outgoing network traffic. Its purpose is to safeguard the computer or network against unauthorized access and potential cyber threats.
2. What is a firewall and why is it used?
A firewall serves as a security device or software that creates a protective barrier between a reliable internal network and an untrusted external network, typically the internet. It filters and controls network traffic, allowing only authorized and safe data packets to pass through while blocking or inspecting potentially harmful traffic.
3. What is a firewall? Explain with an example.
A firewall is a protective barrier that regulates and filters network traffic. Think of it like a security guard at the entrance of a building who checks the identity of people before allowing them in. Similarly, a network firewall checks the data packets coming in or going out of a network and decides whether to permit or deny them based on predefined security rules.
4. What are the 3 types of firewalls?
The three main types of firewalls are:
5. What are the benefits of a firewall?
The benefits of a firewall include:
6. Where are firewalls used?
Firewalls are used in various environments, including homes, businesses, data centers, and any networked systems, to protect them from unauthorized access and potential cyber threats.
7. How to use a firewall?
To use a firewall, you can either configure it through its software interface or use the built-in firewall settings in your operating system. Define the rules for inbound and the outbound traffic, specify allowed applications, and ensure regular updates for optimal protection.
8. What is the difference between a firewall and an antivirus?
A firewall primarily controls network traffic by filtering and allowing/blocking data packets based on predefined rules. An antivirus, on the other hand, focuses on detecting and removing malware, viruses, and other malicious software from your computer or device. While firewalls protect the network, antiviruses protect against specific threats at the system level.
9. Which type of firewall is best?
The best type of firewall depends on the specific requirements and context. A software firewall or a router's built-in firewall might suffice for home users. In enterprise environments, a combination of firewall types like packet filtering, stateful inspection, and application-layer firewalls might be used for comprehensive protection. The best firewall choice depends on factors like security needs, budget, and network complexity.
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