What is a firewall? Everything you need to know

In recent years, the internet has seen many people with bad intentions taking advantage of the chance to break into computers connected to it. After a string of large-scale attacks, computer security has become a bigger concern than ever. To stay safe online, you need to pay special attention to the firewall. This barrier acts as a solid wall that raises the security of your whole computer system. So what is a firewall to have such power? To learn more about firewalls, let's look at them together with Mona Media in the article below.

What is a firewall?

A firewall is a familiar technical term in computer networking. It is a hardware tool, a software tool, or both, built into a system to block unauthorized access and keep viruses out, so that internal information stays protected.

Put simply, a firewall is the security boundary between the inside and the outside of a computer network.

The firewall is essential for any computer system connected to the internet, because it manages what is allowed into the network and what goes out. Having a “gatekeeper” like this to watch over everything that happens is extremely important.

How many types of firewall are there?

Firewalls fall into 2 main types: Personal firewall and Network firewall

Personal firewall

This type is designed to protect a computer from unauthorized access from outside. A Personal Firewall also includes useful features such as monitoring antivirus software and intrusion prevention software to keep data safe

Common Personal firewalls include: Microsoft Internet connection firewall, Symantec personal firewall, Cisco Security Agent and others.

This type suits individuals best, because they usually only need to protect their own computer. The firewall is often built into laptops and PCs.

Network Firewalls

Designed to protect the hosts in a network from outside attacks. Examples are Appliance-Based network firewalls such as Cisco PIX, Nokia firewalls, Symantec's Enterprise Firewall, Juniper NetScreen firewall and Cisco ASA, or Software-Based firewalls such as Check Point's Firewall, Linux-based IPTables and Microsoft ISA Server.

The difference between the 2 types is the number of hosts the firewall has to protect. Remember that a Personal firewall can only protect a single machine, while a Network firewall can protect a whole computer network.

What is the main job of a firewall?

The main jobs of a firewall are listed below:

• It can allow or block services that reach outward, making sure information stays inside the internal network.
• It allows or blocks outside services that want to reach inside.
• A firewall can detect and block attacks and intrusions from outside right away.
• It helps control access addresses (you can set rules to block or allow).
• Controls user access.
• Manages and controls the flow of data on the network.
• Authenticates access rights.
• A firewall supports inspection of the content of information and packets moving through the network.
• Filters packets by source address, destination address, port number and network protocol.
• Administrators can see who is trying to access or break into the network.
• A firewall can be seen as working like an intermediary Proxy.
• Protects system resources from security threats.
• Load balancing: you can run several internet connections at once, and spreading the load across them keeps your connection far more stable.
• Application filtering lets you block specific applications you don't want running on the network.

How does a firewall work?

A firewall has a hard job, because a lot of legitimate data needs to move in and out of a networked computer. It has to tell normal, legitimate traffic apart from data that could cause harm.

A firewall uses rules and exceptions to let good connections through and block bad ones. All of this happens in the background, so users never see it and don't need to do anything.

To see how the firewall works in Windows XP, click Start → Control Panel and double-click the Windows Firewall icon. When the dialog box opens, click the Exceptions tab at the top to see which programs are allowed to receive connections, such as antivirus software and online storage services like Dropbox

On Windows 7 and Windows 10, click Start → Control Panel → System and Security → Windows Defenders Firewall. When the window opens, click the link Allow a program or feature through Windows Firewall in the list on the left to see which programs are allowed to communicate through the firewall.

Windows manages these rules and exceptions automatically, but this is where you go whenever you want to change anything.

What are the drawbacks of a firewall?

No tool is perfect. A firewall offers a lot of useful protection, but it also has some clear limitations:

• A firewall is only a machine. It cannot read and understand every kind of information, so it cannot tell good content from bad content. Put simply, a firewall helps your computer block unwanted sources of information, but only when the address details are clearly defined.
• Some attacks can't be stopped by a firewall if they don't “pass through” it. For example, a firewall can't defend against an attack over a dial-up line, or against data leaking out because someone illegally copied it onto a floppy disk.
• A firewall also can't stop data-driven attacks. It can't scan for and remove viruses in the data passing through it, because new viruses keep appearing, traffic moves fast, and there are many ways to encrypt data so it slips past the firewall.

Even so, the firewall is still the most effective and most widely used protection available today.

Firewall deployment options

Over the past decade, firewall technology has moved forward a lot, and you now have several types of firewall to choose from:

Stateful firewall

The first big step forward in firewall technology came in the mid to late 1990s. Firewalls began inspecting traffic based on the state and characteristics of each network connection, which gave far more complete protection. Tracking connection state lets a firewall allow certain traffic for one user while blocking the same traffic for another.

Next-generation firewalls (NGFW)

Over the years, firewalls have gained many new features, including Deep Packet Inspection (DPI), intrusion detection and prevention, and inspection of encrypted traffic.

Proxy-based firewall

These firewalls act as a gateway between the end user requesting data and the source of that data. All traffic is filtered through the proxy before it reaches the end user. This protects the machine from threats by hiding the identity of whoever made the original request.

Web application firewall (WAF)

These firewalls protect specific applications instead of sitting at the entry or exit point of a wider network. The difference between a proxy-based firewall and a web application firewall (Web application firewall, WAF) is that a proxy-based firewall usually protects the end user's client machine, while a web application firewall is built to protect the application server.

Hardware firewall

A hardware firewall is usually a simple server that works as a router, filtering traffic while running firewall software. These devices sit inside the company network, between the router and the internet service provider's connection point. A business may run dozens of physical firewalls in a single data center.

Software firewall

Most organizations deploy many endpoints across their hardware firewalls together with a central firewall software system. That central system is where threats are analyzed and responded to.

Stateful inspection

This is the basic firewall function: the device blocks unwanted traffic.

Antivirus firewall

With up-to-date threat information, a firewall can quickly spot computer viruses and weak points in network traffic and protect against them.

SSL inspection

SSL (Secure Sockets Layer) inspection checks encrypted traffic for threats. As more traffic is encrypted, SSL inspection has become a key part of the DPI technology built into next-generation firewalls. It acts as a buffer that decrypts traffic before it reaches its destination so it can be checked.

-> See also: Mua SSL, registering an SSL certificate for your website

Intrusion Prevention Systems (IPS)

This security layer can run on its own or be built into a next-generation firewall. A basic firewall identifies and blocks certain types of network traffic, while an IPS goes further, using signature matching and anomaly detection to stop threats from getting into the company network as soon as they appear.

Deep Packet Inspection (DPI)

DPI can be part of an IPS or work alongside one. It has become one of the key features of next-generation firewalls because it analyzes traffic in detail, especially packet headers and traffic data. DPI can also monitor outgoing traffic to make sure sensitive information doesn't leave the company network, a technology known as Data Loss Prevention (DLP).

How to turn on the firewall on Windows 10 quickly

Step 1: To find it quickly, go to your computer's search bar and type “Windows Defender Firewall”, then press enter and select the item with that name.

Step 2: Once you're in Windows Defender Firewall, select the sub-item “Turn Windows Defender Firewall on or off” to turn the firewall on or off.

Step 3: In this last step, just select Turn on Windows Defender Firewall in both boxes on the screen and click “Ok”. That's it, your firewall is now on.

How to turn off the firewall on Windows 10

Method 1: Turn it off in Control Panel

To turn the firewall off, follow the first 2 steps for turning it on. In step 3, tick Turn off Windows Firewall (not recommended) and click OK, and the firewall will be turned off.

Method 2: Turn it off in Windows Security

You can also turn off the Windows firewall through Windows Security:

• Step 1: Press the key combination “Windows + S”
• Step 2: Type into the search bar “Windows Security” and press enter
• Step 3: Select “Firewall & network protection”.

Step 4: Next, select “Private Network” if you're on a home network, or for a public network select “Public Network”.

Step 5: Finally, just turn off Windows Defender Firewall and you're done.

That covers what a firewall is and the details you need to understand what is a firewall. While using it, check regularly that your firewall is working properly. It's also a good idea to run antivirus software and adjust other firewall settings so your computers and company network stay fully protected.