What is Firewall

If you’re someone who browses the internet on your computer, you’re already aware or at least have heard about firewalls.

If not, here is the basic answer to the “what is firewall?” question that newcomers ask. A firewall is the first line of defense when someone tries to attack or send malicious data to your computer.

Firewalls filter all network traffic, examine them, and then according to the set instructions, allow or prohibit that traffic to pass through and connect to your computer.

With that said, let’s take a deeper look into the topic of firewalls. In this tutorial, I’ll talk about firewalls, their types, functions, and the many pros and cons surrounding using them.

What Is a Firewall?

A firewall is a type of digital safety mechanism that you can use to filter out your network’s incoming and outgoing traffic based on a specific set of rules. On a simpler note, a firewall helps you keep out unwanted traffic and only allows communications or connections that are judged safe.

As a firewall engineer, it’s convenient that every system, be it a Mac or Windows, comes with an inbuilt software firewall, as it helps me get a basic idea of the type of firewall I get to work on. 

Firewalls can either be set up independently or together with other apps that strengthen cybersecurity. On the other hand, hardware firewalls focus mainly on larger network devices, like internet routers.

Businesses usually install software firewalls on all staff computers in addition to larger hardware firewalls that protect the entire network, meaning that every data request must pass through a minimum of two firewalls.

How Does a Firewall Work?

So, how exactly does a firewall work? Simply put, a firewall is like an attentive security guard that recognizes millions of possible offenders just by sight. He screens everyone coming into the building, and if he notices something fishy about anyone, he won’t let them in.

Similarly, a firewall works by keeping an eye on and controlling all network traffic. Firewalls use various methods to stop intruders from spreading malicious code onto your system.

However, remember that even though firewalls help protect your system, they are not the same as antiviruses. The main difference between a firewall and antivirus is that a firewall acts as a barrier to block unauthorized access whereas an antivirus is a program that detects and removes malware from your device.

What Are the Key Functions of a Firewall?

Firewalls are an integral part of browsing the internet as they help protect you from malicious activities on the internet. Here are some other functions of firewall that show why are firewalls important:

Network security

Network security is one of the most important functions of firewall. Your computer’s firewall is the first line of defense against unauthorized access, malicious attacks, and cyber threats from the internet.

Firewalls monitor incoming and outgoing traffic, and filter and block suspicious or harmful data packets.

Safeguarding sensitive data

To a firewall engineer like me, protecting sensitive data is an important feature that cannot be understated. A firewall protects your sensitive data and resources within a network by restricting unwanted access to private information, trade secrets, and financial records. Firewalls maintain data privacy and integrity by controlling access to these resources.

Requirements for compliance and regulations

Numerous sectors require you to install firewalls as part of security measures due to specific security standards and compliance regulations. It helps ensure you maintain best practices when these standards are met. 

Protection of endpoint

Firewalls on individual devices, also known as endpoint firewalls, provide an extra degree of security on top of network-level protection by monitoring traffic unique to that device and thwarting endpoint-specific assaults or unauthorized access. 

Types of Firewall

Firewalls come in various forms and are often grouped according to data filtering technique, network location, form factor, and system protection. Some of the different types of firewalls are as follows:

Packet filters

Packet filters monitor incoming and outgoing packets and determine whether they should be allowed or denied according to the origin and target Internet Protocol (IP) addresses, protocols, and ports. This is also known as a static firewall.

Application firewalls

These firewalls are capable of examining data from the OSI model's application layer, such as an HTTP request. 

Application firewalls are a lifesaver for someone who might not be familiar with attacks via firewalls as they immediately block any suspicious activities that it determines may be causing harm to your network or are not safe for it.

Stateful inspection firewalls

It is a kind of packet filtering that regulates the flow of data packets via firewalls and is also known as dynamic packet filtering. They can check if a packet is a part of a specific session. It will only allow your communication if and when the session between two endpoints is completely established; if not, it will prevent communication.

Software firewall

As I mentioned earlier, a software firewall is an inbuilt feature of your computer’s operating system. A software firewall protects your system from potential danger that may arise when opening an insecure website or phishing emails.

Hardware firewall

Amongst the many different types of firewalls, hardware firewalls stand unique as you have to use a physical device, like a router, to create a network border.

Hardware firewalls inspect all incoming and outgoing network traffic and enforce access rules and other security policies since it is the first point of contact for any network links that cross this boundary.

Circuit-level gateways

A circuit-level gateway is a firewall that regulates TCP and UDP connections between the transport and application layers of the OSI model by examining basic packet information without inspecting the content

Next generation firewalls (NGFW)

Also known as intelligent firewalls, these firewalls can complete all firewall tasks, but on top of it, they also include features like cloud-delivered threat intelligence, integrated intrusion prevention, and application awareness and control.

Cloud firewall

Think of cloud-based firewalls as virtual security guards for your network, but instead of being physical devices, they're software-based programs deployed in the cloud.

Just like a traditional firewall, they keep unauthorized users out of your private network, but they do it by filtering data at the cloud level rather than within your physical network.

Advantages and Disadvantages of Using a Firewall

As neat as firewalls are, they aren’t flawless. Let us take a look at the advantages and limitations of firewall:

Advantages

1. Monitors network traffic

Imagine your network to be a congested highway with a lot of data traveling through it. The firewall monitors all the cars (data packets) coming into and going out of your network, much like a traffic cop.

It determines which cars should be stopped because they may be transporting hazardous materials and which ones should be permitted to pass based on rules and filters.

Firewalls can modify these rules and filters according to the kind of "cargo" (data) they anticipate with the help of an experienced IT staff, making sure that only safe traffic passes through.

2. Prevents virus attacks

Virus attacks are extremely dangerous since they can abruptly and severely disrupt a company’s digital operations, as well as your system.

It's critical to set up defenses to keep systems safe from attacks because hundreds of thousands of new threats emerge daily.

In this context, a firewall is crucial because it regulates user access points to their systems, thwarts viral attacks, and shields users from the potentially enormous damage caused by a virus attack, which varies greatly in type.

3. Deters hacking

These days, with businesses rapidly shifting to digital operations, there are more opportunities for hackers and other cyber crime forces to engage in unethical behavior. As a result, there is an increase in data theft and system hostage situations.

Since firewalls stop hackers from obtaining unauthorized control over your data, emails, systems, and more, using them has become even more important in the fight against these criminal actions.

A firewall has the power to block hackers and discourage them from moving on to a more manageable target.

Disadvantages

1. Cost

The cost of implementing firewalls into network systems is entirely dependent on their nature. Hardware firewalls are typically more expensive than software firewalls since they require the assistance of qualified IT specialists to install and configure them into network systems, as well as ongoing maintenance.

As for a software firewall, even if you are completely new to the concept, you can easily install a software firewall by searching something like “How to use firewall protection?” on the internet.

2. User limitation

A firewall protects your machine against unwanted network access; yet, while firewalls are advantageous for the individual user, they are significant limitations of firewall in large companies at times.

Employees can be banned from doing specific tasks based on firewall policies. This has a significant impact on organizational productivity. This sometimes causes staff to take shortcuts, which can lead to major security issues.

3. Malware attacks

Firewalls can defend computers against the most common kinds of trojans, but they cannot defend against other kinds of malware, which may infect the system by seeming to be reliable data. You should install anti-malware software to deal with malware.

Final Words

Now that you know what is firewall, and its uses, you will most probably agree when I say firewalls will continue being a part of the future of network security as long as the internet is riddled with hackers and malicious content.

Firewalls help keep our systems safe and provide a smooth experience when connecting with other devices around us. If you want to learn more about firewalls and their application, check out the blogs and courses on offer at upGrad today!

Frequently Asked Questions  

1. Which firewall is best?

There is no certain answer to this as all companies that offer firewall services will guarantee their products’ effectiveness. You can decide which firewall you want based on your needs.

2. Are firewalls 100% secure?

As much as companies would like to advertise their firewalls as 100% secure, I don’t think firewalls are 100% secure. Firewalls are often targeted by hackers, and there are cases of data leaks from such attacks.

3. Can a firewall block IP?

Yes, you can block specific IP addresses in the many different types of firewalls on offer.

4. How to use a firewall?

To use a firewall you need to first set it up on your device and then you can use your firewall to allow or deny specific sites access to your computer network.

5. How to install a firewall?

If you’re on Windows, you can enable/install the firewall option in the “System and Security” tab in your system’s settings. As for Mac users, you can find your device’s firewall settings in the “System Settings” menu.

6. Does the firewall block VPN?

A firewall can block a VPN, however, most don’t block VPNs by default and will do so only if you configure it to block a VPN.

7. What is a proxy firewall?

A proxy firewall is a network safety feature that safeguards network resources by filtering communications at the application layer.

8. Why is a firewall needed?

Firewalls help protect you against malicious or unauthorized network traffic.

9. Can firewalls detect attacks?

Firewalls can detect attacks and store the information in the logs, which you can access later. 

10. Can a firewall detect VPN?

Firewalls can detect VPN connections.