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What is A Network Firewall?

Network firewall is a network security equipment that observes network communications and determines whether particular traffic should be allowed or blocked, consisting of a set of security requirements. It operates in layer 3 (network layer) in the Open Systems Interconnection (OSI) model.

What Is A Network Firewall

Figure 1. Some of the major Network Firewalls

For more than two decades, firewalls have served as the first line of protection in network security. It provides a boundary separating protected, regulated internal networks that can be recognized, and untrustworthy external networks local network system; the standard firewall keeps all connected devices safe from unwanted incoming packets, including someone attempting to hijack one of the PCs. The network system is a smaller counterpart of your computer system, which may have several more desktops, data centers, as well as other equipment connected to the firewall. Using a network firewall for the company's network and IT security requirements, however, one must take a stronger method to firewall administration than when using one for your private networks.

Both hardware and software firewalls are available. Here is the description of both of the firewalls.

Hardware firewall:

Hardware firewalls are available as independent solutions for business usage or as integrated components of routers as well as other networking devices. These are an important component of any conventional cybersecurity system or network design. Physical firewalls generally come with at least four access points, allowing numerous computers to connect. A more comprehensive network firewall solution can be found for more prominent organizations.

Software firewall:

Software firewalls can be installed on a computer or supplied by an operating system or network hardware vendor. They may be altered and offer limited control over functionalities and security features. A web application firewall can defend a system against common control and allow applications, but it won't protect it from more complex malicious activity in the network.

Any traffic incoming or outgoing the system must pass through a network firewall, which evaluates each incoming packet and devaluates fit the set security protocols. A firewall, when correctly designed, enables users to view whatever assets they require while preventing unauthorized users, attackers, malware, bugs, or other dangerous applications from gaining access to the secured system.

How Does Network Firewall Work?

A network firewall, simply stated, is in charge of restricting access between devices such as PCs, computers, and hosts. As a result, the most typical configuration is a protected and unsafe network. The safe network is referred to as the internal network, while the unsecured network is referred to as the external network.

The network firewall's function and placement are to allow network connections to pass via the gateway, which can subsequently block any unlawful packets. Packets are filtered by a basic firewall based on IP ranges and port facilities. Sorting the traffic depending on the information on the package is a good comparison. Any familiar IP address is usually accepted, whereas any packet sent to someone else is generally returned. For firewalls, the process of monitoring is basically the same.

The network firewall's role has evolved over time following the broader services delivered across contemporary networks. Network Address Translation (NAT) is a feature of modern firewalls that allows numerous devices to share a restricted set of network addresses. Differentiation of network strategy is another feature of network firewalls that prioritizes particular traffic, ensuring that data is received on a timely basis. For example, to guarantee appropriate functioning, voice over IP (VoIP) is one sort of application that requires distinction. The usage of multimedia services will only grow in the future. If email and VoIP packets arrive simultaneously at the firewall, the VoIP packets should be handled first since the application is more prone to delays.

Network firewalls can also examine packet payload (data). This can be used to filter other connections, prevent harmful data packets, and/or prevent cyberattacks.

How To Build A Network Firewall?

Building a network firewall is not easy without prior knowledge and experience. Here is how you can build your network firewall step by step.

First, let's figure out what you will need to build a network firewall. Here is a list of the required equipment:

  • A computer with decent configuration with CD-ROM and USB Port
  • Ethernet Ports
  • A blank CD to burn the operating system.
  • USB Pendrive, floppy disk, or hard drive.

Now, after getting the equipment ready to use. Here is how to build a network firewall.

  1. Design of the firewall : To employ a firewall, one must first create basic infrastructure. The network we're using as an experiment seems to be quite common. The Internet is accessed using a cable connection. Here, it will consist of an internal Local Area Network (LAN) with machines, a personal cloud server, and a Voice over IP adaptor behind the firewall. The configuration will also have a different public wifi network from everything else. It will deploy the wireless connection, or Wireless Local Area Network (WLAN) on the network interface, which is often where multiple servers are located. In our circumstance, wireless communication is kept separate from the local network. It's ideal while the network isn't permitted to join the LAN without specific permission. The design would not be the same for all the circumstances. It will depend on the volume of the equipment connected to the network. However, different organizations will have different criteria for the network firewall and the design of the firewall would be in accordance with the requirement.
  1. Burn the Operating System in a CD: Before burning it into a CD, it will be necessary to choose an operating system. It is better to select a Linux or FreeBSD based distribution for the firewall's operating system. However, there are several best distributions available for network firewalls. OPNsense, Devil Linux and IPFire are three of them. Download the latest available version of any of these operating systems. Unzip the package and find the iso file to make a bootable CD.
  1. Hardware Arrangement: For building a network security firewall, hardware arrangement according to the configuration is a must. You will need another floppy disk or USB thumb drive to store the firewall's configuration with the Devil Linux operating system. The network firewall can run without an internal storage drive. Only it requires CD-ROM to boot the operating system, CD or USB thumb drive to provide the boot file, floppy disk, or another USB thumb drive to store the configuration, cable, and ports.
  1. Boot the OS and Configure: Once the pieces of equipment are ready to go, power up the machine and boot the operating system. You may need to set up the operating system with some requirements. When the operating system is booted up. Follow the configuration steps below.

How to Setup Network Firewall?

Here is how you can set up the network firewall following the steps:

  1. Log in to the operating system: After booting up the operating system, you first need to log in to the operating system with administrative privilege. Use 'root' as the username in the Devil Linux distribution and hit enter. A prompt will open, and you will be instructed to type 'setup' and hit enter again.
  1. Configuration: After login, you need to configure the operating system and the firewall for use. You can navigate the configuration widget with the keyboard. You may need to adjust the hostname, timezone, and other settings under the simple setup menu.
  1. Service Selection: Now you will need to select services to set up the network firewall. As discussed with Devil Linux distribution, it is flexible to select services and configure. You can enable the SSHD to allow the SSH shell connection to connect to the local DNS services.
  1. Network Configuration: First, select the 1NIC (network interface card) and configure the first network connection for your network firewall. Now, set up the first network interface eth0. This is the connection that your digital subscriber line or network adapter should be connected to. If you haven't yet determined which component your ethernet cards require, think of your requirements and choose the best one for you. To locate an IP address attached to eth0 and show it on screen, just use ifconfig commands and other filters. Select yes or no from the Dynamic Host Configuration Protocol (DHCP) selection on the eth0 panel. If you select no, you will be able to input the IP address. You can enter your service's static IP underneath if you have one. Alternatively, choose yes and return to the Networking menu, where you'll find the 2NIC setup option. Now, eth1 will be the name of the additional NIC. Even if the component is identical to the previous, choose it again. This is the networking port that you'll use with a crossover cable to link to your ethernet connection, gateway, or computers. Although the standard address is good, you might need to change this. Devil Linux has not set up any firewall rules. If you're utilizing three network connections, choose the DMZ3FW, and if you're just using two, use the FW2. One of those will put up simple host-based firewall roles for two or three network interface cards. Last but not least, you must save all of the settings modifications. You may do this via the interface or by typing save-config at the command line. It will check your present configurations to your previous configurations and request if you are sure you want to save your edits. After making any modifications to the system, you must save the configuration settings. Instead, they'll be lost when the computer reboots. Fortunately, if you make a mistake, restarting will undo your error.

How to Connect to Private Network Firewall?

Connecting to the private network firewall can be done from the menu of the Devil Linux distribution. Here is how to connect to a private network firewall.

First, run the ifconfig command in the SSH shell terminal:

ifconfig <interface> <ip_address> netmask <netmask>

Here, the interface is the network card you want to configure (eth0, eth1). The IP address is the private IP address you would connect with the firewall. The netmask refers to the sub netmask you want to use.

For example, the below command will set the eth0 adaptor with the provided IP and sub netmask.

ifconfig eth0 100.100.100.10 netmask 255.255.255.0

Now, run the ifconfig <interface> command in the terminal. For your eth0 network card, the command would be ifconfig eht0

Afterward, run the next command in order to edit the configuration file. Edit the file with the previously provided information and save it.

nano /etc/network/interfaces

How To Turn Off Network Firewall?

Turning off the network firewall requires the services to be stopped and disabling to start again when to reboot the machine.

  • Use the following command to stop ipchains service:
service ipchains stop
  • Use the following command to stop iptables service:
service iptables stop
  • Use the following command to disable the ipchains service from starting when you restart the machine.
chkconfig ipchains off
  • Use the following command command to stop the iptables service from starting when you restart the machine:
chkconfig iptables off

Why Network Firewalls Are Important?

The online world has become an indispensable element of everyday life. Internet connectivity is employed in a variety of settings, ranging from homes to large enterprises. The information we keep on our systems is personal and, in many cases, commercially valuable. As a result, potentially malicious traffic can affect data in various situations, including hijacking it, destroying it, transferring it, etc. Network firewalls are used to prevent such. As previously stated, the firewall serves as a barrier between the system and external sources such as webpages, other devices, and connections. As a result, the value of a firewall in network security is recognized in the following areas:

  • Traffic Monitoring: The availability to track network activity is the foundation of all network firewall advantages. Data flowing in and out of the systems can introduce risks to your services. Firewalls defend the system by examining and controlling network traffic and applying pre-set rules and filtering. Depending on what you observe flowing in and out of your firewall, you can change your security settings.
  • Stop Hijacking: However, as organizations move further towards digitalization, criminals and other cyber attackers are more likely to follow security vulnerabilities to exploit the system. Firewalls have grown even more critical as a result of the increase in data theft and offenders keeping systems hostages since they prevent hackers from obtaining unwanted access to your data, communications, computers, and more. A firewall can either entirely block a hacker or persuade them to select a less tempting target.
  • Prevent Malware and Spyware and Adware: Preventing malware from obtaining access and infiltrating the network is a much-needed advantage in today's data-driven society. The number of entry points thieves can exploit to control your networks grows as your technologies become more complicated and strong. Spyware, malware, and adware programs capable of penetrating your networks, managing your devices, and stealing your data - are some of the most apparent forms unwelcome persons obtain access to. Firewalls are a crucial line of defense against malicious payloads.
  • Prevent Virus Attack: Virus infection may bring your digital activities to a halt faster and more aggressively than anything else. With large numbers of emerging challenges being created every day, you must have safeguards in place to maintain your system's security. The capability to restrict the system's access points and thwart virus attacks is one of the most evident benefits of firewalls. Relying on the type of virus, the cost of damage from a virus attack on the system might be immeasurable.
  • Privacy Protection: The maintenance of privacy is an overall advantage. By helping to keep the data and the users' data safe on a regular basis, you can create a trusting environment for the service users. Nobody wants their information stolen, particularly when it's evident that preventative measures might have been implemented.

The improved network infrastructure may also be a key differentiator and a unique selling proposition for employees and consumers. The value grows as your company's business becomes more essential.

What Are The Different Types Of Network Firewalls?

Typical firewalls are installed straight across a network connection and monitor all traffic traveling over it. They must determine which internet protocol traffic is acceptable and which packets are part of a cyberattack while doing the monitoring.

Here are five different types of firewalls for different purposes though the idea is similar.

  • Packet filtering firewall: Packet filtering firewalls are installed directly at the places where equipment like switches and routers perform their functions. On the other hand, these firewalls do not route packets; instead, they check each one to a list of pre-defined parameters, such as authorized Ips, packet format, destination port, and other features of the IP header. Problematic packets are often discarded indiscriminately; those are not transmitted and therefore stop existing. Although packet filtering may not offer the measure of protection required in every use circumstance, there are times when this minimal firewall is an excellent choice. Packet filtering is a fundamental level of security that can defend against potential attacks for modest or growing enterprises.
  • Application-level firewall: This sort of device is essentially a gateway and often known as a proxy firewall operates as the single point of entry to and exit route from the system. Application-level firewalls, also known as Web Application Firewall (WAF), improve network performance based on a variety of factors, including the Standard HTTP request text, as well as the function for which they are meant. While application-layer firewalls offer significant data protection, they can significantly impact system performance and are difficult to monitor. Application-layer firewalls are the most effective way to safeguard corporate assets from online application vulnerabilities. They can both protect critical data from unauthorized access from inside the firewall and deny access to malicious websites. They can, however, cause network latency.
  • Stateful inspection firewall: State-aware technologies evaluate each item and maintain a note of if it is part of a running TCP or other networking connection. This provides higher protection than packet filtering or route tracking individually, albeit at the expense of network quality. This multidimensional assessment firewall, which analyzes the exchanges in progress across several protocol levels of the Open Systems Interconnection (OSI) architecture, is another version of packet filtering. The adoption of such a network firewall is beneficial to most enterprises. These systems act as a more comprehensive bridge between the company's current systems and other infrastructure and external resources. They may also be very useful in protecting network devices against specific threats like DDoS.
  • Next-generation firewall: A standard Next-generation firewall integrates packet sniffing with vulnerability scanning, DPI, and other networking security devices like Intrusion Detection Systems(IDS), spyware blocking, and malware. Unlike regular firewalls, which just analyze the protocol signature of the transmission, a deep packet examines the actual data carried by the packet. A DPI firewall may monitor the course of a web browsing session and determine if a packet content when combined with other protocols. NGFWs are most effective when they are linked with other security measures, which often need a good level of expertise.

How Is It Different Than The Application Firewall?

Before going to the differences, let's see the different layers of the Open Systems Interconnection (OSI) model that will help to differentiate the application firewall and network firewall.

Here are the seven layers of the Open Systems Interconnection (OSI) model-

  • Physical Layer
  • Data Layer
  • Network Layer
  • Transport Layer
  • Session Layer
  • Presentation Layer
  • Application Layer

Technically, the distinction between application and network firewalls is based on the levels of security they function on. Network firewalls function on levels 3 (network) and 4 (transport), whereas web application firewalls perform on layer 7 (applications). Web application firewalls are more engaged with activity into and out of your bigger system, whereas network firewalls are more focused on traffic into and out of the network.

Typically, network firewalls serve as the primary form of digital security for enterprises. It is adept at defending network-wide threats that can penetrate systems through the local area network and attack associated endpoints. A network firewall is still required if you allow internet connectivity to any company location.

Host-Based Vs. Network Firewalls: What Are The Differences?

A host-based firewall is a suite of apps built on a regular computer that offers safety to the host server. On the other hand, a network-based firewall analyzes traffic flowing from the Internet to a secure local area network and vice-versa.

Simple applications called host-based firewalls are commonly used for residential or individual PCs. They are less costly than network firewalls and defend a single PC. In contrast, A network firewall is far more advanced than a host-based firewall, and it is commonly employed by big enterprises with a high number of computer systems. These firewalls are more costly than their counterparts, but they are significantly quicker and more complex.