What is NAT?

There is nothing like opening your laptop and connecting to the Internet from the comfort of your home; uploading photos to your social networks, checking your email inbox, and having so many online tools to make your life easier. But behind all this, there is an element that makes it possible: NAT (Network Address Translation).


What is NAT?


It stands for Network Address Translation, which is a function used by industrial routers to convert multiple private IP addresses within a local network to a public IP address to allow sending and receiving information from the Internet.

In addition, NAT is used by organisations when they want multiple devices to use a single IP address, which is also applied by most home routers. So, it is likely that your cable modem or DSL router is making use of this feature as you read this post.


How Does NAT Work?


To understand how NAT works imagine that you have a laptop connected to a home network, which in turn is connected to a router that provides internet access. Now imagine that you use the laptop to search for shoe offers in different stores.

This generates a request; it’s in this instance where the NAT makes its entrance sending it in an IP packet to the router so that it can then send it to the internet and from there to the browser you are using to do your search. But before the request leaves the boundaries of the home network, the router changes the internal IP address, i.e., the local private IP address, to a public IP address.

The router transforms the private IP address that your device or computer is using to an address that can be supported by the cloud and vice versa. So, now you know that your cable modem or DSL router has a little automated translator built in to make the connection between your device and the internet possible.

What if the IP packet retains its private address? In that case, the receiving server will have no idea where to return the response to the request made by the device within the home network. The point is that a private IP address can’t be routed to the internet. So, it would be impossible for your device to connect to the cloud through a private IP address, as the internet servers are programmed to reject such addresses.

However, this is not something you need to worry about as all routers currently on the market are capable of translating these IP addresses without difficulty and without the need to make adjustments to their configuration.

What is a Private IP Address?


This is the question you are probably asking yourself at this point. A private IP address is the one assigned by the router to any device or computer that connects to a network. It should be noted that each device within the same network will have a unique private IP address so that they can all communicate with each other and share resources even if they are not connected to the entire Internet. This makes it difficult for a host or user outside the network to establish a connection with any of these devices.

So private IP addresses are useful to reinforce security within a home or business network. Through a wireless connection, for example, you can connect a printer and print documents from a computer or device that is connected to the same network. But if your neighbor tries to send its files to your printer it will not be able to do so unless it is added to the network.


Types of NAT


There are three types of NAT, which are used by people and organisations in different contexts, although they have the same operation.

Static NAT

This is defined as all those local addresses that have the same IP address when converted to public. So that the public IP that is generated at the end will be associated with the router to which the devices and equipment of the local network are connected.

Dynamic NAT

Unlike the static NAT, this NAT uses a set of public IP addresses to be variably assigned to the router each time it performs the translation of the local address.


An acronym that refers to Port Address Translation. It is actually considered a type of dynamic NAT whose job is to convert several local IP addresses into a single public one. There are organizations that use PAT to put all activities carried out by their employees on the network under a singular IP address, whose supervision is then exercised by a network administrator.


Why is NAT important?


Let’s take an in-depth look at the role that NAT has played in IP preservation and its limitations in the field of security services.

NAT and its role in IP conservation

When it comes to IP addresses, they are a feature that makes it possible to identify each device connected to the Internet. In the case of IP version 4 (IPv4), this makes use of 32-bit numbered IP addresses, giving a margin of 4 billion IP addresses to allocate. This seemed sufficient during the 70s when it was created.

But as time went by, Internet networks underwent an aggressive expansion. Of course, this does not reflect that the entire world population has access to an Internet connection.

Millions of people tend to have several devices connected to a network such as laptops, desktops, smartphones, tablets, televisions, assistants, etc. So, it is not surprising that the number of devices accessing the internet is much higher than the number of available IP addresses.

This is where the NAT comes into play by routing all private IP addresses associated with multiple devices on a local network into a single public IP address. This ensures that more public IP addresses are available, even as the number of private IP addresses continues to expand.

More IP addresses? IPv6 coming to the rescue

In 2012, specifically on June 6, IP version 6 (IPv6) was launched, which arose from the need to provide space for a greater number of IP addresses. For this purpose, IPv6 uses 128-bit numbered IP addresses, which is far less than the number offered by the previous version.

Even so, the use of NAT for IPv4 addresses will remain standard practice. But IPv6 is not only intended to provide a wider range of IP addresses but also to make the routing process for these addresses more efficient. This means that, unlike IPv4, IPv6 will relieve routers of the burden of processing traffic.