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What is a Firewall? Understanding What They Are and Which Type is Right For You

You already know that your computer needs to be protected, and you probably do what you can to keep it safe. But not only your computer but also the online servers need to be protected. Otherwise, they are especially vulnerable to attacks. Whether you’re protecting a computer, a network, or a server, how are hackers and malicious traffic kept at bay? With firewalls.

Put, a firewall is like a virtual doorman. It protects the computer and, well, everything else. Whenever you visit a website with your computer, you’re connecting to another kind of computer: a web server. And since servers are computers, they are vulnerable to the same types of attacks as your personal computer.

You would not connect to another device – like a stranger’s computer or iPhone – without protection, would you? If you did, you’d be afraid that person could steal your data or attack your tool. The same goes for linking to an internet server. And from the web server’s perspective, it requires protection between itself and the thousands of connections it makes to computers every day.

 What is a firewall?

It is a device used for network security. It monitors both incoming and outgoing traffic to either allow or block data packets based on safety rules.

Its objective is to develop a barrier between your internal network and traffic flowing in from external resources – like the rest of the Internet. That blocks hackers, viruses, and other malicious traffic.

There are preset rules to analyze and filter traffic and redirect data from suspicious or unsecured sources to prevent attacks on your network.

 Firewalls protect your website from the following:

Brute force attacks: Hackers try hundreds of combinations of usernames and passwords to get your credentials.

DDoS attacks: An attack where thousands (or even millions) of fake packets are sent to cause server overload and cripple your website.

Break-ins: Unapproved users who attempt to access your computer or web server.

Malware: Opponents who want to infect your device or server with malware that can steal your details, harm your computer, and even spread to other devices.

Ports and IP addresses

A firewall acts as a data guardian at your computer’s entry point, called a port. That is where data flows between external and internal devices – and it’s a vulnerable spot on your network.

An Internet Protocol (IP) address is a separate address assigned to a device or network. The IP address houses the ports – your network ports live inside the IP address. Only specific source addresses can even get through the IP address. After that, the firewall provides additional filters so that only specific traffic sources can access those ports. You, your network owner, can access any port; a visitor can only access some of them – or none of the firewalls prevents it.

Types of firewalls

There are several types of firewalls, and which one you use depends on your specific needs (single device or network or server protection).

Software vs Hardware

All firewalls fall into two main categories: Software or hardware firewalls. It’s best to have both to ensure the best possible protection, but some people will choose one. Either way, both types of firewalls create an obstacle between your computer system and the rest of the Internet.

Software application: This type of firewall is a program installed on your computer. It regulates traffic through applications and ports, for example, to monitor and manage users, create logs, and block applications.

Hardware: This physical type of firewall is the equipment that sits between the gateway and your network. Your router is one type of hardware firewall, although more specialized devices exist for larger purposes.

What you should know about hardware firewalls

Hardware firewalls are complex for some people to set up, especially if you only have one computer to protect or run a small business but don’t have an experienced IT department. Hardware firewalls can cause performance problems, primarily when used with a software firewall. They also don’t provide the comprehensive protection many PC owners need, such as application blocking.

However, for individuals and businesses that need to protect an entire network of computers, a hardware firewall is much more critical. It isn’t easy to find software with this level of safety. Also, cyberpunks can easily disable a software firewall once they find a way to get past it, but a physical device is much harder to manipulate.

Let’s now enter into more detail about the different types of firewalls.

Packet filtering firewalls

A packet consists of the data between your computer system and a server. When you send an email, submit a file, or click on a link, a packet goes from your computer to the web server; when you go to a website and load a web page, the webserver sends a packet to your computer.

Firewalls that filter packets examine the packets (i.e., the label and source IP addresses) and block them if they don’t match the specified rules. Thus, if you try to access a website that has been reported as malicious, your computer will not load it to protect you.

While this type of firewall is widely used, it is not the most effective, especially when compared to next-generation firewalls (which we will discuss next). Protection is limited because the firewall doesn’t check the content of a request, only the request itself, which means it may let a malicious request from a trusted source through.

If you are currently using a packet-filtering firewall, you should at least deploy another, more advanced firewall. However, if you’re using a more advanced firewall, this probably isn’t necessary, as it should already include this type of protection.

Next-generation firewalls

Next-generation firewalls (NGFWs) are better equipped to protect your device and network. These firewalls offer the following:

  • Virus protection
  • Application monitoring
  • Deep packet inspection
  • Encrypted traffic inspection
  • Intrusion protection

That means the request itself and the data in the request are examined to ensure that no malicious content is transmitted.

Proxy firewalls

Proxy firewalls are best recognized for monitoring traffic for layer protocols (e.g., FTP and HTTP). Proxy firewalls filter application-level traffic and act as intermediaries between end systems. The customer sends a request to the firewall, which is either allowed or blocked after comparison with security rules.

Network Address Translation Firewalls

Network Address Translation Firewalls, or NATs, permit different devices with their network addresses to connect to the Internet via an IP address, hiding the individual IP addresses. It is similar to how proxy firewalls work a NAT is an intermediary between traffic and a group of computers. When an enemy scans a network for IP addresses, he cannot find details about all online devices.

Stateful Multilayer Inspection Firewalls

Stateful Multilayer Inspection Firewalls, or merely Stateful Firewalls or SMLIs, filter packets at multiple levels – application, network, and transport. Each packet is inspected in its entirety and allowed to pass through each layer only if it meets security policies. In addition, stateful firewalls recognize patterns, making it easier to block unauthorized traffic.

This technology contrasts to packet-filtering firewalls, which are sometimes referred to as “stateless.” Stateful firewalls place a heavier load on your device, but they store and analyze much more packet data.

Do I need a firewall?

Now that you know the answer to the question “What is a firewall?” you may be wondering if you need one. And you do. Any device that connects to the Internet, such as a computer, needs protection. And that doesn’t just apply to computers. Any tool that connects to the Internet needs protection, such as your smartphone.

It gets worse. Imagine this: If you don’t have a firewall on a device connected to the Internet, a hacker could get into it, take it over, install any malware, and learn all your sensitive data, such as the state of your bank accounts and your login credentials. Hackers can also access your camera and microphone to watch and eavesdrop on you.

If a hacker gains access to a web server, they can change your website credentials, destroy or remove your website, and even install malware on your website that infects your visitors’ devices. If that occurs, you can say goodbye to visitor traffic and sales.


A personal firewall is not meant for a network or a web server but only for a single computer. You probably already have one – it’s usually standard equipment on a Mac or Windows computer, as is antivirus software.

Personal firewalls have the following tasks:

  • They analyze all incoming and outgoing traffic and determine whether the connection to your device’s applications is secure or not.
  • They protect the ports you use to connect to websites and applications. The attackers can’t see that these ports are open when they are used.
  • Prevent cyberpunks from accessing and taking control of your computer.
  • Defend against attacks that get through by accident.

A built-in firewall on your computer or the same protection provided by antivirus software is great. But what if you have a WordPress website that you need to protect? That’s where these cloud-based WAFs come in. A reputable online service and security plugin will protect your site and keep you and your visitors safe. Also, choose a web host with a high-security level for its servers, including a reliable firewall. 

We’re a team made up of enthusiastic StopWebForms developers who decided to turn their common experience into this website so they could help other businesses protect their websites from web form spam and abuse.

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