What is a NAT Firewall? | How Does it Works

April 3, 2019 by Shigraf Aijaz

Ever wondered what happens after you search up something on the internet? It seems so simple, doesn’t it? You just fire up the browser application and visit any site or search up anything you want! However, things are far more complicated in reality.

The main task of reaching up to the desired URL or presenting the asked search result is a complex process. Furthermore while online there are numerous possibilities of infections and malware.

These malware or hackers are always on and about looking for opportunities to infiltrate your network and exploit you. Just like at a secure facility, there are also guards present at your network gates.

These guards work up ways to stop or avoid any malware or hacker from infiltrating the system. One such guard is the NAT firewall present in routers.

Now for those of you who don’t know, allow me to shed some light over what NAT firewall is.

What to expect of a NAT Firewall?

The Network Address Translation also known as NAT is a networking method that allows many devices to access the internet through a common gateway. The devices under NAT all share the same public IP address along with a unique private IP Address.

The information on the internet is in the form of small data packets. These data packets are meant to be delivered at the exact required location. To make this method precise, the ISP assigns each user an identity called the IP address.

As within a home or an office, some devices are collectively connected, routers work on data sorting to take the bulk off. The ISP gives off a single IP address to every router or user when it connects to it. The router then further gives each device connected to it a different internal IP address.

This internal IP address helps the router deliver the requested information to every device. As for firewalls they are basically guards! A firewall:

  • Protects the network from malware.
  • Keeps away hackers and cyber criminals from penetrating the system.
  • Allows only requested traffic to enter.

The NAT firewall feature is present in routers. The routers are somewhat of a “sorting hat” which “sorts” every device connected to it with a unique private IP address using NAT. Along with the sorting, it also works as a firewall by successfully blocking out malware and unwanted traffic.

Types of NAT Firewalls

There are three main types of NAT. The use of these varies with the needs. Here are the kinds of NAT available:

1. Static NAT

It is used for servers that demand the use of one IP address only at all times. This is where the name “static” of this NATTING method arises from.

In it, the NAT device is assigned a pool of public IP addresses. The private IP addresses are then statistically mapped to any one of the available public addresses.

In it, each server has the same public IP address assigned to it, so that server A has one IP address, server B has another and etc.

2. Dynamic NAT

Here yet again a pool of IP address is present in the NAT device. However, in this method, the devices borrow the IP address from the pool and then later return it after use.

So if computer 1 needs a public address, it would borrow it from the pool and then later return it after use. The next time computer 1 requires an address, it would be assigned a different one.

This is as the previous address used by computer 1 would already be in use by some other device. This is where the name dynamic is derived from.

A company purchases a specific amount of public IPs as per to their needs. This way the users who wish to communicate on the internet at one time will have a limited option to opt from.

3. PAT

Port Address Translation or PAT is an extended version of NAT. It works by assigning one single IP address to a group of devices connected on a LAN network.

This method was designed to conserve IP address. It is mostly used in homes and small offices. The ISPs assign one single IP address to the router. The router then works on distributing those.

In this method, each device that connects to the router is given a separate port number along with the ISP provided a public IP address.

This port number along with the IP address acts as an identity of the device. This way even though collective devices share one single IP address they are still recognizable by the router.

Why VPNs come with a NAT Firewall?

Now am sure you must be wondering why to have a VPN with a NAT firewall when one already exists in the routers. Well, usually while using the internet without a VPN your routers are the perfect protector of your systems.

However, with a VPN in place the encryption game goes strong. The VPNs encrypt your data present between the connection and your device. This encrypted tunnel of information even surpasses the NAT firewall present in the routers.

The NAT firewall is, therefore, unable to ward off the malware and hackers that may try to enter in the connection. This why the VPN providers add up a NAT firewall feature within the service. This feature then plays an active role in filtering the network from any suspicious activity.

Although this seems to be a convenient feature however most people vote against it. One downside of having a NAT firewall feature in the VPN is that it makes your device traceable by a VPN provider or a third party source.

A substitute to NAT firewall is to merely assign a same public IP address to all the users connected to one server. With a significant number of users using the same public IP address rather than separate ones it aids better to anonymity.

Is your router equipped with a NAT Firewall?

If you are wondering, whether your router is equipped with a NAT firewall or not this is the way to figure that out:

  • Connect two devices to the router at once. Let’s say your smartphone and your laptop.
  • On each device fire up a Google search of “what’s my IP address?”
  • The same IP address for both the devices means that there is a NAT firewall present.

The devices have a shared public IP address, but there is a different internal IP address assigned to each device. It may be more difficult to identify the presence of a NAT firewall in a VPN. The VPN documentation may have It mentioned.

Most VPN services come with an option to enable or disable the NAT firewall. Some may offer it as an add on, up for purchase.

NAT Firewalls and Torrenting

If you are someone who frequently does torrenting, for legal work of course! NAT firewall may be troubling for you while torrenting. With a NAT firewall in place, you won’t be able to seed or leach properly as the NAT firewall cuts you off with many torrent users.

However, torrenting is not nearly impossible with a router as some routers are somewhat less strict. It is the public wifi set up that is strict and doesn’t allow torrenting.

If your router does happen to be strict, you can just subscribe to a VPN service for torrenting. A VPN allows you to open a port through which you can bypass the NAT firewall.  However, opening up a port means a compromise to your security.

A connection with an open port is easily recognizable. This may be an easy way for people to track you down as you may be the odd one out!

Additional benefits of NAT Firewall

The NAT firewall wasn’t originally created as an intent to be used as a firewall. It was built to basically make the networks more mobile.

It was established with the mind that through it every device won’t have to be re-addressed if there was a change of network. Upon network change, only the NAT device would have to be assigned a new public IP address.

Now NAT is considered to be a handy tool in conserving the global airspace. This is because the IPv4 tool that assigns each device an IP address is short on those. Giving out a separate IP address for each device would be cramming the global airspace.

This is where the NAT device comes into use. The IPv4 protocol simply assigns the NAT device with an IP address. The method then further distributes internal IP addresses to each device that connects to the NAT device.

The IPv6 was introduced to replace IPv4 as it has a larger address space, but the adoption process is slow. This is why NAT devices are useful to keep the internet running.

Closing lines

Am sure the burning fires of curiosity regarding how the data packets and information transfer occurs have extinguished. Also, now you can surely rest easy knowing that there are precautions already in place to keep you safe and sound online!

The Internet is a vast world with many mysteries to uncover. Enthralling how it works doesn’t it?

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