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The consequences of cyberattacks may be disastrous for organizations, not to mention expensive—it is estimated that the cost of cybercrime in 2017 was almost $600 billion.

Due to the continued growth in the number of targeted cyberattacks, managed services providers (MSPs) are under greater pressure to protect their customers’ networks from cyber threats and malware.

Knowing that having a firewall (or several firewalls, for that matter) may make a significant impact on network security is second nature to you as an MSP.

Have anyone asked you or have you ever wondered what is a computer firewall and how it works?

What Is A Computer Firewall And How Does It Work?
What Is A Computer Firewall And How Does It Work?

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What Is Network Firewall Security?

Protecting networks and devices against a wide range of security concerns, such as illegal access from outside your customers’ networks, is one of the most important functions of firewalls. Customers’ internal networks can also be used to alert you to possibly dangerous efforts to connect from within them.

Having a clear understanding of the purpose of firewalls for your clients is critical to successfully delivering service as a managed service provider.


Using a firewall, you may safeguard your private networks against unwanted and unverified access through the use of an internet connection. Firewalls can be either hardware or software-based, or they can be a hybrid of the two types of firewalls.

So, what do they truly do all of the time?

Firewalls safeguard your computer or a group of computers connected to a network from malicious websites or unprotected network ports that might be exploited by hackers. They assist in stopping potential assailants in their tracks before they can cause any damage.

Incorporations, households, schools, and intranets (private networks within an organization), network firewalls may be found protecting the networks they protect.

In addition, a network firewall can be set to prohibit network users from accessing websites on the internet from within the network.

For example, parents may put parental restrictions on their children’s surfing habits, and your employer may block specific websites in order to keep you focused on the task at hand while you are at work.

How Does Firewall Monitor and Regulate Network Traffic?

For data attempting to access your computer or network, firewalls are either software or hardware devices that act as a filter system for the data.

When a packet is received by a firewall, it is scanned for malicious code or attack vectors that have previously been recognized as potential risks.

The firewall blocks data packets from accessing the network or reaching your computer if they are reported as a security concern and are determined to be such by the firewall.

Security firewalls can monitor and control network traffic in a number of different ways, depending on the configuration.

These techniques might include the following:

1. Packet filtering is a type of packet filtering.

Packets are tiny chunks of information. The packets attempting to enter the network are screened by the firewall against a set of filters when the firewall employs packet filtering.

These filters filter out packets that match specific recognized risks while allowing the remaining packets to proceed to their intended destination without being blocked.

2. The use of a proxy server.

These firewalls are extremely safe, but they are not without their own set of disadvantages. They operate at a slower rate than other types of firewalls and are frequently restricted in terms of the types of applications that they may accommodate.

Instead of acting as a filtration mechanism through which data is sent, proxy servers act as intermediaries between two parties.

Through the process of constructing a virtual replica of your computer behind the firewall, they prevent direct connections between the customer device and incoming packets, therefore safeguarding your network location from any bad actors.

3. Inspected in a formal manner.

A stateful inspection firewall compares a variety of components in each data packet to a database of trustworthy information, in contrast to static filtering, which just analyzes the packet headers.

These components include the IP addresses of the source and destination computers, as well as the ports used by the computers.

In order to be permitted via the firewall, incoming data packets must match the trusted information in a significant amount. Stateful inspection is a more recent technique of firewall filtering that is becoming more popular.

What is the purpose of a firewall?

What is the purpose of a firewall?
What is the purpose of a firewall?

A firewall serves as a type of gatekeeper. It keeps an eye out for efforts to get access to your operating system and prevents any unwanted traffic or unidentified sources that come through.

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What is the mechanism through which it accomplishes this? A firewall is a type of filter that works as a barrier between your computer and another network, such as the internet.

One way to conceive of a firewall is as a type of traffic controller. It contributes to the protection of your network and information by controlling network traffic. This involves limiting incoming network traffic that has not been requested and verifying access by analyzing network traffic for anything harmful, such as hackers and malicious software.

A firewall is generally pre-installed on your operating system and security software unless otherwise specified. It’s a good idea to double-check that those features are enabled as well.

Also, double-check your security settings to ensure that they are set up to automatically install updates.

So, what exactly are the different types of firewalls?

5 Types of Firewalls

1. Packet filtering 

This is the most traditional type of firewall, but it has the advantage of having no influence on the general performance of your system.

A packet-filtering firewall, sometimes known as a checkpoint, is a security measure that is implemented at a traffic router or switch.

The packet filter is responsible for analyzing the data packets that pass through your router. In most cases, this filter may assess the source IP address, the destination IP address, the packet type, the source port, and the destination port, among other things.

In this case, it does not look for specific information within the packet, only general information on the surface level.

Depending on how you configure your firewall, you can filter packets from specific IP addresses or specific ports to allow or disallow them.

Because this sort of firewall is very basic, it is straightforward to dodge if you are a committed attacker with the right tools.

Using this sort of firewall in combination with other, more powerful firewall design is the ideal strategy to employ.

2. Proxy service firewalls (also known as service proxy firewalls).

In network security, the proxy service firewall is a technology that can assist you in protecting your network security by filtering communications at the application layer.

It simply acts as a bridge or intermediary between your internal network and external servers on the internet.

It is sometimes referred to as a gateway firewall because it uses stateful and deep packet inspection technologies to examine incoming traffic, which makes it more secure.

3. Firewalls with stateful multi-layer inspection (SMLI) are another option.

The stateful multi-layer inspection firewall provides typical firewall features and keeps track of any connections that have already been established with the system.

It filters traffic based on the state, port, and protocol of the traffic, as well as administrator-defined rules and the context of the communication. The data from previous connections as well as packets from the same connection are used in this process.

Stateful packet inspection is used by the majority of firewalls to keep track of all internal traffic. Because of its use of multi-layer monitoring, this firewall is a step above traditional packet filtering.

However, because it is still unable to discriminate between good and malicious online traffic, you may need to use other software to make this distinction.

4. Firewalls with unified threat management (UTM) capabilities

It is possible to use a unified threat management firewall in conjunction with other security programs, such as intrusion prevention and antivirus, to provide a more comprehensive security solution.

Additional services, such as cloud management, may be incorporated within the umbrella of services provided by UTM.

5. Firewalls of the next generation (NGFW)

Next-generation firewalls are more complex than traditional firewalls such as packet-filtering and stateful inspection.

Why? They provide higher degrees of security by going above and beyond basic packet filtering to examine a packet in its entirety.

That entails not only checking the packet header, but also the contents and source of a packet as well. In order to combat more sophisticated and developing security threats, such as advanced malware, next-generation firewalls (NGFW) are used.

5. Firewalls that use network address translation (NAT)

A network-attached firewall (NAT firewall) is capable of analyzing internet traffic and blocking unwanted communications.

In other words, it will only allow inbound web traffic if it has been requested by a device on your private network.

Rules for the Firewall

As previously stated, network traffic that passes through a firewall is compared to rules in order to determine whether it should be permitted to get through or not.

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Showing a few instances of firewall rules is a simple method to demonstrate what firewall rules look like, so we’ll do that right now. Consider the following scenario: you have a server with the following list of firewall rules that apply to inbound traffic:

  • Accept all incoming traffic to the public network interface on ports 80 and 443 that is new or previously established (HTTP and HTTPS web traffic)
  • Change port 22 of your firewall to accept inbound traffic from IP addresses of non-technical staff in your workplace (SSH)
  • Accept fresh and established incoming traffic from your workplace IP range to the private network interface on port 22 on your computer’s network card (SSH)
  • Keep in mind that the initial word in each of these instances is either “accept,” “reject,” or “drop,” depending on the situation.
  • When a piece of network traffic meets a rule, this describes what the firewall should do as a result of that match.
  • When traffic is accepted, it is allowed to pass through; when it is rejected, it is blocked but the message “unreachable” is returned; and when it is dropped, it is blocked but the message “unreachable” is returned.

The remainder of each rule is comprised of the condition that each packet must satisfy in order to be matched. As it turns out, network traffic is checked against a set of firewall rules in a sequence, or chain, from first to last, in order to determine whether it is allowed to pass.

To put it another way, once a rule is matched, the corresponding action is implemented to the network traffic that was matched.

Rule 2 would be applied first in our case, and the attempt to establish an SSH connection by an accounting employee would be refused before the effort to make the connection would even be verified against rule 3.

Those who work as system administrators, on the other hand, would be approved because they only match rule 3.

Policy by Default

It is common for a chain of firewall rules to fail to explicitly cover every potential situation in a network environment.

Therefore, firewall chains must always include a default policy that is comprised of simple action and no other options (accept, reject, or drop). Assume that the default policy for the chain in the previous example was set to drop.

The traffic would be discarded if it came from a computer outside your workplace and sought to establish an SSH connection to the server because it did not meet the criteria of any of the rules.

If the default policy was set to accept, anyone, even your own non-technical workers, would be able to connect to any open service on your server if the policy was set to reject.

This would be an example of a firewall that has been improperly designed since it simply prevents a portion of your employees from gaining access.

What are Hardware and Software Firewalls?

Hardware and Software Firewalls

Hardware Firewalls

Hardware firewalls are systems that are separate from the machines they protect and that filter information coming in from the Internet as it enters the computer they guard.

The majority of broadband Internet routers are equipped with a built-in firewall. Devices that function as hardware firewalls examine data that comes in from the Internet and determine whether or not the information is secure.

Simply put, packet filters, often known as simple firewalls, analyze the data itself to determine information such as the data’s location and its source.

In order to assess whether information should be deleted or allowed through, the firewall compares the information it has gathered against a predetermined list of permissions.

More information may be examined by hardware firewalls as they grow more advanced in their capabilities to analyze more data.

These sorts of firewalls offer advantages for residential and small business users since they need little to no setup and may prevent several nodes (computers) from patching into the same router at the same time.

But the primary disadvantage of most home-use hardware firewalls is that they only analyze data that is entering a computer and do not examine data that is exiting a computer, which is a significant security risk.

It is possible that someone may ask, “Isn’t that the point?” In a way, yeah. It’s true. Malicious software, on the other hand, is frequently sent over the Internet in the form of a Trojan horse.

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Although the data may appear to have been “wrapped” by a reputable source, it is possible that malicious software has been included within the code to do harm.

Additionally, certain assaults may result in the target computer being transformed into a zombie or a computer bot, which then proceeds to disseminate data on a large scale.

Because a hardware firewall does not detect outgoing information, it will not take into account an increase in traffic or the substance of that traffic.

Firewalls that are software-based

In comparison to hardware firewalls, software firewalls offer two major advantages them. A software firewall’s ability to monitor outbound data traffic is the first of these features.

Apart from preventing a computer from becoming a bot or a zombie, it can also prevent computers from broadcasting other malware, such as worms or computer viruses, over the network. The second advantage of software firewalls is that they may be configured to meet specific needs.

These applications can be customized to fit the specific requirements of the user, such as if the user requires permissions to be relaxed when they are playing online games or viewing an online movie, for example.

The primary problem of software firewalls, on the other hand, is that they can only protect a single machine. Every computer must be equipped with a legally licensed firewall program. A hardware firewall, on the other hand, has the capability of protecting every computer that is connected to it.

Additional Layer of protection

It is not a terrible idea to utilize a software firewall in addition to a hardware firewall. Not only will they not interfere with one another, but they will also give several levels of protection, which can help to keep a computer protected.

Software firewalls, on the other hand, are intended to be used in combination with antivirus software. This is due to the fact that a firewall can only do so much to protect you.

While a firewall can prevent a known danger from entering the network, any stealthy attempt to breach physical barriers will be successful. This is especially true in social engineering assaults, in which the computer user is duped into installing malicious software on his or her computer.

Having antivirus software as a backup is beneficial in this situation because it can either prevent or clean up any infection that manages to get through the initial layer of security protection.

Additionally, keeping all computer software up to date, particularly the operating system software, will aid in protecting the machine against known dangers.

This also works in conjunction with firewalls to prevent invasive attacks from being launched. Furthermore, it is essential for all computer users to become familiar with the types of dangers they can avoid, particularly those that can get past a firewall.

Surprise attacks may be avoided by not clicking on links in instant messaging and not opening attachments in chain e-mails, among other things. All of these approaches, when used together, may assist in protecting a computer and keeping it secure and clean.

Computer Firewalls
Computer Firewalls

CONCLUSION On What Is A Computer Firewall?

With only a few resources consumed by your computer, a good software firewall should run in the background of your computer, leaving only a minimal footprint on overall performance.

The firewall software must be updated on a regular basis in order to stay up with the newest technical advancements and to provide efficient protection against the most recent network attack tactics and techniques.

FAQs About Computer Firewalls

What are the three different types of firewalls?

There are three basic types of firewalls that are used by businesses to protect their data and devices by preventing destructive elements from entering the network: packet filters, stateful inspection firewalls, and proxy server firewalls.

What is a computer firewall, and what exactly does it accomplish?

Unauthorized access into or out of a computer network is prevented by using a firewall, which is a type of security mechanism. Firewalls are devices that are installed between a network or a computer and another network, such as the internet. It is in charge of controlling the network traffic that comes into and leaves the computer or network.

What is the purpose of a firewall in a computer?

By protecting your computer or network from harmful or superfluous network traffic, firewalls provide security against outside cyber attackers and keep your data safe. Firewalls can also prevent dangerous software from gaining access to a computer or network by using the internet to communicate with it.

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