What is a Firewall?

Summary

The video script explains what a firewall is, highlighting its role as a security system that filters incoming internet traffic to prevent unauthorized access to a private network. It compares a network firewall to a building's firewall, emphasizing its function to contain potential threats. The script details how firewalls work with customizable rules, including examples of access control lists that allow or deny traffic based on IP addresses, ports, and other criteria. It also distinguishes between host-based and network-based firewalls, illustrating their applications and the importance of using both for maximum network security.

Takeaways

• 🔒 A firewall's primary function is to prevent unauthorized access to a private network by filtering incoming internet traffic.
• 🚫 It acts as a barrier, blocking unwanted traffic while allowing desired traffic to pass through, creating a safety zone between the private network and the public internet.
• ⚠️ The presence of hackers and malicious traffic on the internet necessitates the use of a firewall to protect private networks from potential harm.
• 🏢 Large organizations with numerous computers and servers are particularly reliant on firewalls to prevent disruptions and unauthorized access.
• 🔧 Firewalls are customizable through access control lists determined by network administrators, who decide what can enter and leave the network.
• 📋 Firewall rules can be based on IP addresses, domain names, protocols, programs, ports, and keywords, providing granular control over network traffic.
• 🌐 Network-based firewalls protect an entire network, operating at the network layer and applying management rules to prevent harmful activities.
• 💻 Host-based firewalls are software solutions installed on individual computers to provide localized protection.
• 🛡️ The use of both network-based and host-based firewalls provides layered security, ensuring that if one layer is breached, the other can still protect the network.
• 🏢 Organizations often employ a combination of firewall types for comprehensive network security, leveraging the strengths of each to safeguard their infrastructure.
• 🛠️ Firewalls come in various forms, including as built-in components of routers for smaller organizations or as standalone products for larger entities.
• 🌐 Modern high-tech environments, both at home and in businesses, rely on firewalls to maintain network integrity and security against external threats.

Q & A

What is the primary function of a firewall?

A firewall's primary function is to prevent unauthorized access to a private network by filtering incoming information from the internet, thereby creating a safety barrier between the private network and the public internet.

Why are firewalls particularly important for large organizations?

Firewalls are particularly important for large organizations because they have many computers and servers that they do not want to be accessible to everyone on the internet. This prevents hackers from disrupting the organization's operations.

How does a firewall compare to a firewall in a building structure?

A firewall in a building structure provides a barrier to contain a fire and prevent it from spreading to other parts of the building. Similarly, a network firewall stops harmful activity from spreading into the network and causing harm.

What are the rules that a firewall uses to filter network data called?

The rules that a firewall uses to filter network data are called an access control list, which can be customized by the network administrator to determine what can enter or leave the network.

Can you provide an example of how firewall rules might be applied based on IP addresses?

In the script, an example firewall's access control list shows some IP addresses that are allowed to enter the network, while traffic from one specific IP address is denied based on the set rules.

What types of criteria can firewalls use to make rules?

Firewalls can make rules based on IP addresses, domain names, protocols, programs, ports, and keywords to control access to the network.

How do port numbers play a role in firewall rules?

Port numbers can be used in firewall rules to allow or deny incoming data. For example, the script mentions that data using port numbers 80, 25, and 110 is allowed, while data using port numbers 23 and 3389 is denied.

What is a host-based firewall and how does it differ from a network-based firewall?

A host-based firewall is a software firewall installed on a computer to protect only that computer. In contrast, a network-based firewall is a combination of hardware and software that operates at the network layer and protects the entire network.

Why might an organization use both network-based and host-based firewalls?

Organizations might use both types of firewalls to ensure maximum protection. A network-based firewall protects the entire network, while host-based firewalls provide individual protection for each computer and server, ensuring that any harmful data that gets past the network firewall can still be stopped.

Can you explain the role of a network-based firewall in the context of a router or a cloud infrastructure?

A network-based firewall can be a standalone product used by large organizations, built into a router for smaller organizations, or deployed in a service provider's cloud infrastructure to manage rules applied to the entire network and stop harmful activity before it reaches the computers.

Outlines

00:00

🛡️ Introduction to Firewalls

A firewall is a system designed to prevent unauthorized access to a private network by filtering information from the internet. It blocks unwanted traffic and permits wanted traffic, creating a safety barrier between a private network and the public internet. Firewalls are crucial for large organizations with many computers and servers to protect against hackers and malicious traffic. The term 'firewall' originated from a building structure that prevents fires from spreading. Similarly, a network firewall stops harmful activity from spreading into a private network. In today's tech world, firewalls are essential for homes and businesses to keep networks safe.

05:01

🔍 How Firewalls Operate

Firewalls filter incoming network data using rules, also known as an access control list, set by network administrators. These rules determine what can enter and leave the network, allowing or denying permission based on IP addresses, domain names, protocols, programs, ports, and keywords. For example, a firewall might allow traffic from certain IP addresses or port numbers while blocking others. This ensures that only authorized data can pass through, protecting the network from harmful activities.

🖥️ Types of Firewalls

Firewalls come in different types, including host-based and network-based firewalls. A host-based firewall is a software installed on a computer to protect that specific device. Examples include built-in firewalls in later versions of Microsoft operating systems and third-party firewalls like Zone Alarm. Network-based firewalls, on the other hand, are a combination of hardware and software that operate at the network layer. They protect the entire network by applying management rules to stop harmful activity before it reaches individual computers.

🏢 Network-Based Firewalls in Action

Network-based firewalls can be standalone products used by large organizations, built into routers for smaller organizations, or deployed in a service provider's cloud infrastructure. Many organizations use both network-based and host-based firewalls to ensure maximum protection. Network-based firewalls protect the entire network, while host-based firewalls offer individual protection for computers and servers. This dual approach ensures that if harmful data gets past the network firewall, the host-based firewalls on each computer can stop it. The video concludes by thanking viewers and encouraging them to subscribe for more content.

Keywords

💡Firewall

A 'firewall' is a security system designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. In the context of the video, it serves as a barrier between a private network and the public internet, preventing unauthorized access and protecting against malicious traffic. The script uses the analogy of a building's firewall to explain its function in network security, emphasizing its role in containing harmful activities to safeguard the network.

💡Unauthorized Access

Unauthorized access refers to the use of a computer system or network without permission. The video script highlights the importance of firewalls in preventing such access, ensuring that only approved traffic can enter a private network. This concept is central to the theme of network security, as it underscores the potential risks posed by hackers and the need for protective measures like firewalls.

💡Traffic

In the script, 'traffic' refers to the data packets that are sent and received over a network. A firewall's job is to filter this traffic, allowing wanted data to pass through while blocking unwanted or potentially harmful data. This concept is crucial to understanding how firewalls maintain network security by controlling the flow of information.

💡Hackers

Hackers are individuals who use their technical skills to exploit vulnerabilities in computer systems or networks, often with malicious intent. The video script mentions hackers as a threat that firewalls are designed to counteract, emphasizing the need for robust security measures to protect against unauthorized intrusion and potential harm to the network.

💡Access Control List (ACL)

An Access Control List is a set of rules that a firewall uses to determine which traffic is allowed or denied access to a network. The script explains that these rules are customizable and managed by network administrators, who decide what can enter or leave the network. ACLs are a fundamental aspect of how firewalls enforce security policies.

💡IP Address

An IP address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. The video script discusses how firewalls can make rules based on IP addresses, allowing or denying traffic from specific addresses. This is a key mechanism by which firewalls control network access.

💡Port Numbers

Port numbers are numerical identifiers used in networking to specify which specific process is being addressed for incoming or outgoing connections. The script provides an example where firewall rules control access by allowing or denying data using specific port numbers. This illustrates how firewalls can regulate traffic at a granular level to enhance security.

💡Host-Based Firewall

A host-based firewall is a type of software firewall that is installed on an individual computer to protect it. The video script mentions that operating systems like Microsoft's later versions come with built-in host-based firewalls, and third-party options like Zone Alarm are also available. This type of firewall is relevant to the video's theme as it represents one layer of network security.

💡Network-Based Firewall

A network-based firewall is a combination of hardware and software that operates at the network layer, protecting the entire network rather than individual computers. The script explains that this type of firewall can be a standalone product or part of a router, and it's used to manage rules that protect the network from harmful activities. This concept is integral to the video's message about comprehensive network security.

💡Rules

In the context of the video, 'rules' refer to the security policies set by network administrators to govern the behavior of a firewall. These rules determine what kind of traffic is allowed or blocked, and they can be based on various criteria such as IP addresses, domain names, protocols, and port numbers. The script uses the term to illustrate how firewalls enforce security measures.

💡Domain Names

Domain names are human-readable names assigned to IP addresses, used to identify entities in a network. The video script mentions that firewalls can make rules based on domain names, which is an example of how firewalls can filter traffic at a higher level of abstraction than just IP addresses. This is part of the broader strategy of network security depicted in the video.

💡Protocols

Protocols are a set of rules governing the format and transmission of data. The script indicates that firewalls can create rules based on protocols, which is essential for understanding how firewalls can control different types of network communications. This concept is part of the video's discussion on the various criteria that firewalls use to filter traffic.

💡Programs

In the context of the video, 'programs' refer to software applications that can be subject to firewall rules. The script suggests that firewalls can control which programs are allowed to send or receive data, which is an important aspect of managing network security and preventing unauthorized activities.

💡Keywords

Keywords in the context of the video script refer to specific terms or phrases that firewalls can use to filter traffic. The script does not provide a detailed example of this, but it implies that firewalls can be configured to block or allow traffic based on the presence of certain keywords, adding another layer of specificity to security rules.

Highlights

A firewall is a system designed to prevent unauthorized access to a private network by filtering internet traffic.

Firewalls block unwanted traffic and allow wanted traffic, creating a safety barrier between a private network and the public internet.

Hackers and malicious traffic are common threats on the internet, making firewalls essential for network protection.

Firewalls are crucial for large organizations with multiple computers and servers to prevent disruption from external threats.

The term 'firewall' originates from building structures, where it acts as a barrier to contain fire and prevent its spread.

A network firewall functions similarly to a building's firewall, stopping harmful activity from affecting a private network.

Firewalls are essential for both home and business networks to ensure safety in the high-tech world.

Firewalls work by filtering incoming network data based on customizable rules, known as an access control list.

Network administrators determine the rules for what can enter and leave a network, allowing or denying permissions.

Firewall rules can be based on IP addresses, domain names, protocols, programs, ports, and keywords.

Examples of firewall rules include allowing or denying traffic from specific IP addresses or using certain port numbers.

Firewalls come in different types, including host-based and network-based, each serving different protection needs.

Host-based firewalls are software installed on a computer to protect it individually.

Network-based firewalls combine hardware and software, operating at the network layer to protect the entire network.

Large organizations often use both network-based and host-based firewalls for maximum protection.

If harmful data bypasses the network firewall, host-based firewalls on individual computers can provide a secondary line of defense.

Transcripts

What is a firewall?

A firewall is a system that is designed to prevent unauthorized

access from entering a private network by filtering the

information that comes in from the internet.

A firewall blocks unwanted traffic and permits wanted traffic.

So a firewall's purpose is to create a safety barrier between a private network and the

public internet.

Because out on the internet, there's always going to be hackers and malicious traffic

that may try to penetrate into a private network to cause harm.

And a firewall is the main component on a network to prevent this.

and a firewall is especially important to a large organization that has a lot of computers and

servers in them.

Because you don't want all those devices accessible to everyone on the internet where

a hacker can come in and totally disrupt that organization.

That's why you need a firewall to protect them.

A firewall that's used in computer networks is very similar to how a firewall works in a building

structure.

In fact..this is where the word 'firewall' came from. A firewall in a building structure

provides a barrier so that in the event of an actual fire, on either side of a building,

the firewall is there to keep the fire contained and to keep it from spreading over to the other

side.

So the firewall is there to keep the fire from destroying the entire building.

But if the firewall wasn't here, the fire would spread to the other side and the whole

building would be destroyed.

And a network firewall works in a similar way as a structure firewall. It stops harmful

activity before it can spread into the other side of the firewall and cause harm to a private

network.

In today's high-tech world, a firewall is essential to every home and especially a business

or an organizaton to keep their network safe.

A firewall works by filtering the incoming network data

and determines by its rules if it is allowed to enter a network, these rules are

also known as an access control list.

These rules are customizable and are determined by the network administrator.

The administrator decides not only what can enter a network but also what can leave

a network.

These rules either allows or denies permission.

So as an example, here we have some rules in a firewall's access control

list.

It shows a list of IP addresses that have been allowed or denied by this firewall.

And as you can see, traffic from some IP addresses are allowed to enter this network..but

traffic from one IP address has been denied.

So, if traffic from this IP address tried to get into this network, the firewall will deny

it because of the rules that are set in the firewall..

But the other IP addresses are granted access because the rules

Allow them.

Firewalls don't just make rules based in IP addresses, but they can also make rules based

on domain names, protocols, programs, ports, and keywords.

Let's say in this example, the firewall rules are controlling access by port numbers.

and let's say that the rules have allowed incoming data that's using port number 80,

25, and 110, and the data using those ports have been given access to this

network.

So any incoming data that's using those ports, can pass through the firewall.

But also in this firewall, the rules have denied any data that's using port numbers

23 and 3389.

So any incoming data that's using those port numbers, the firewall will deny access

and it won't get passed the firewall.

So in a nutshell this is how firewalls basically work.

Firewalls come in different types.

One type is called a host-based

firewall, and this is a software firewall.

This is the kind of firewall that is installed

on a computer and it protects that computer

only and nothing else.

For example, later versions of Microsoft

operating systems come pre-packaged with a

host-baseball firewall. And you can see that example here.

There are also 3rd party host-based firewalls can be purchased and installed on a computer.

So for example, Zone Alarm..which is a popular 3rd party host-based firewall.

And also a lot of antivirus programs will have a built in host-based firewall.

Another type of firewall is called a network-based firewall.

A network-based firewall is a combination of

hardware and software, and it operates at the network

layer.

It is placed between a private network and the public internet

But unlike a host-based firewall, where it only protects that computer, a network-based

firewall protects the entire network, and it does this

through management rules that are applied to the

entire network so that any harmful activity can be

stopped before it reaches the computers.

Network-based firewalls can be a stand alone product ...which is mainly used by large organizations.

They can also be built-in as a component of a router..which is what a lot of smaller organizations rely on.

Or they can also be deployed in a service provider's cloud infrastructure.

Now, alot of organizations will use both network- based and host-based of firewalls..

They will use a network-based firewall to protect the entire network as a whole...and

they will also use host-based firewalls for their individual protection for their computers

and servers.

And by doing this, it'll ensure maximum protection .

Because if harmful data just so happens to get passed the network firewall...the host

based firewalls on each computer will be there to stop it.

So thank you everyone for watching this video on firewalls. Please subscribe and I'll see you in the next video...thank you.