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What is a NAT Firewall? Complete Guide 2020

As simple as browsing on the internet might seem to a person accessing the World Wide Web for the first time, access to the internet involves complexities and intricacies, the names of which might sound like gibberish to the uninformed layman. 

Simply put, to access the internet depends on a complicated relationship between a secure LAN (Local Area Network), which might be anything from an office Wi-Fi setup and the much less secure internet. 

The connection a router has to the internet is prone to many vulnerabilities, and to foster secure browsing, a line of defense is needed. A firewall is that line of security and works by guarding and surveying the communications taking place between the LAN and the internet.

A NAT firewall is fundamentally a modified version of the standard firewall and amps up the security of a user while browsing up a notch. To aid our readers in understanding how a NAT firewall works, we’ve compiled an article which deals with everything you might want to know- including why it might be a stupid decision to do without it.

What is a NAT Firewall? 

Before we jump into what a NAT firewall is and how it works, it might be important that we understand what a firewall is first. Simply put, a firewall is a network security tool that monitors and surveys incoming and outgoing data packets on the pre-requisite of some previously determined rules. 

Based on these predetermined security regulations, the firewall chooses to block and permits specific packets of data, coming from an external source such as the internet. The firewall can either be a hardware network device, or software often referred to as a ‘personal firewall.’ Most Operating System these days a personal firewall built-in.

A NAT firewall, on the other hand, works by modifying the IP information, so that the packets of data can reach their required destination. To gain a better understanding of the differences between a standard firewall and a NAT firewall, let’s have a look at how a NAT firewall works.

How Does a NAT Firewall Work? 

 As stated above, the basic principle of a NAT firewall involves the modification of existing IP information on the packets of data being sent from a device. The NAT firewall, also known as The Network Address Translation provides a networking method through which multiple devices on a single network have access to the web through a common gateway.

The devices under the NAT firewall share the same public IP address with each other, whereas all the devices have an allotted private IP address, which is unique to each of the devices. 

Up to this point, we’ve mentioned the phrase “data packets” quite a lot, and if you’re a newbie to the realms of IT, the implication might be vague. Well, you may think of these data packets as the currency through which all transactions take place on the internet. 

Whenever you type in a website’s name or make a simple Google search, you request information to be sent to you by sending countless of these data packets. To make sure that you receive the exact information you asked for, these data packets need to be marked with an IP address. 

For every device that connects to the internet, a unique IP address is assigned, which lets the ISPs (Internet Service Provider) know about the particular information to be sent to each device. Since most networks have an arsenal of devices connected to a single LAN, the router goes through the data packets and sorts them accordingly.

Throughout the sorting process, the router creates an internal IP address for each device on the network, unlike the single public IP address assigned by the ISP. The internal IP address assigned by the router helps the router delivers the exact information to the device that requested it in an organized manner. 

As for firewalls, a router uses a NAT firewall to modify the information about the IP address marked on the data packets. A consequent result of all this sorting that takes place is that all unrecognized data packets are thrown out of the mix, and the NAT firewall ensures that only the traffic requested by users is allowed to reach its final destination. 

Using the NAT firewall renders it impossible for most threats, such as malware and spyware from being inserted into your network through a device, since it keeps hackers and other cyber-criminals out of the network and permits only the requested traffic to enter.

How Can You Be Sure That Your Router Has NAT Enabled?

Most Wi-Fi routers have the NAT firewall already enabled, but if you’re harboring any doubts as to whether or not your router has NAT enabled, we’ve got an easy fix for it.

First, make sure that you’ve got at least two devices on the same Wi-Fi network. After you’ve connected both the devices, make a Google search on both the devices for “What’s my IP address?” 

If the search turns up the same results for both devices, chances are your router probably has the NAT firewall enabled. The reason for both the devices having the same IP address is that they share a common public IP address, but have a unique private IP address. 

However, before you make the search on Google, makes sure that you’ve got your VPN software disabled. Since a VPN works primarily by concealing your actual IP address with the IP address of one of its server, after some intense digging around, however, you might find your real IP address within the records of your VPN provider. But if they’ve got a strict no-log policy, unfortunately, you might find yourself a bit out of luck. 

What Are The Types of NAT firewalls?

The use of the NAT firewall varies with the needs of a company, or an individual, which is why there are three kinds of NAT firewalls available: 

#1- Static NAT:

This kind of NAT server is used where the demand is to use the firewall for one IP address, at all times. Hence, the name “Static NAT” used in the NATTING method.

With Static NAT, the device is assigned an arsenal of public IP addresses. The private IP addresses are then pinned to any one of the available public addresses. 

Moreover, each server has the same public IP address assigned, which enables server B to be distinguished from server B since both of them have varying IP addresses. 

#2- Dynamic NAT:

With a dynamic NAT firewall, a similar pool of public IP addresses is available for the device to choose from. The only difference lies in the fact that in this NATTING method, the device borrows the IP address and returns it after use.

To explain this, let’s consider Device X. If Device X needs a public IP address, it would borrow one from the arsenal of public IP addresses and later return it after use. The next time Device X needs a public IP address; it would be assigned one different from the one they had previously used.

The reason for Device X being assigned another IP is because the previously allocated IP address would already be in usage by some other device, which is where the name “Dynamic” arises. 

#3- PAT: 

Simply put, PAT or Port Address Translation is an extended version of NAT firewall. PAT functions by assigning a single public IP address to a group of devices connected on a single LAN network.

Unlike the types of NAT mentioned above, PAT works to conserve IP addresses. Mostly used in small setups such as homes and offices, the ISPs assigns a single IP address to the router in use. Later on, the router works by distributing the IP address further along with the network. 

With PAT, each device connected to the router is assigned a specific port number, along with a private IP address. The port number combined with the unique private IP address works as the identification of each device on the network and helps the requested information to be sent to its destination accurately. 

Connection Between The NAT Firewall and VPNs?

As mentioned above, the functionality of a VPN depends on it masking the IP address of its users. Despite this, most VPN providers specify having a NAT firewall and use it for advertising their VPNs.

A Virtual Private Network, abbreviated as a VPN encrypts all the online communication, that is the device’s internet traffic, and instead of sending it through a default router, uses an intermediary server in a location chosen by the user. 

When a VPN is enabled, all the traffic that passes through the network undergoes encryption, which makes it impossible for the NAT firewall to distinguish between requested information since everything looks the same. The process of encryption so critical to the functioning of a VPN renders the NAT firewall useless since it can’t separate unwanted traffic from requested data.

Owing to this reason, many VPNs integrate NAT firewalls. Instead of your default Wi-Fi router doing the data sorting typically of a NAT firewall, the VPN server filters out unwarranted traffic. Most of the times, the NAT firewalls are built into the VPN by default, other times they are offered as a bonus perk. 

Additional Advantages to Using a NAT Firewall: 

Apart from being a crucial part of the line of defense most Operating Systems offer, NAT offers other benefits, as follows:

  • NAT firewall helps conserve IP addresses.
  • Makes networks more portable, since only the router would be re-addressed instead of all the devices on the network.
  • The IPv4 protocol works in tandem with NAT enabled devices and is the reason why the internet is up and running since, without the protocol, we would be cramming the global airspace.

So, What Do You Do From Here?

At the end of the article, we can only hope that we’ve quenched the thirst for the knowledge of NAT firewalls and how they work.

That being said, we can only remind you at the very end to make sure that the router you use is NAT enabled since the firewall plays a crucial role in your safety on the internet. If you’re planning to invest in a VPN anytime soon, make sure you pick one out with a NAT firewall to block off pesky malware from corrupting your devices.

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