What is NAT (Network Address Translation)?

Are you aware of how network devices, such as routers, translate the IP addresses of devices in a private network to a single IP address used to communicate with the internet? Let me tell you if you are unaware of the answer to this query. It is possible by using a NAT or Network Address Translational method.

This article will discuss all there is to know about NAT (Network Address Translation). But, before exploring NAT in detail, let’s first go through the list of topics under the table of contents (TOC) that we will cover in this article.

Table of Contents (TOC)

• What is NAT?
• Addresses of NAT
• Working of NAT
• Types of NAT
• Advantages of NAT
• Disadvantages of Network Address Translation
• Conclusion

Let’s start with the most basic question, i.e., what is NAT?

What is NAT?

Network Address Translation (NAT) is a method used by network devices, such as routers, to translate the IP addresses of devices in a private network to a single IP address in order to communicate with the internet. This allows multiple devices to share a single public IP address and access the internet through a single connection.

You can commonly use NAT in home networks, allowing multiple devices to connect to the internet using a single internet connection and a public IP address. It is also used in more extensive networks, such as corporate or academic networks, to conserve the number of public IP addresses needed and provide an additional security layer.

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There are different types of NAT, including static NAT, dynamic NAT, and NAT with Port Address Translation (PAT). We will discuss these different types of NAT in the later section of the article.

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Addresses of NAT 

In a network that uses Network Address Translation, there are two types of IP addresses:

• Private IP addresses (inside address)
• Public IP addresses (outside address)

Let’s explore each of these two types of IP addresses in detail.

• Private IP addresses: Devices in the private network use these addresses in order to communicate with each other. These addresses are not unique and are not reachable from the internet. Private IP addresses are assigned from a range of reserved addresses, such as 192.168.0.0/16 or 10.0.0.0/8.

• Public IP addresses: Devices on the internet use these addresses in order to communicate with devices in the private network. These addresses are unique and are assigned by the Internet Service Provider (ISP). A device in the private network can be reached from the internet using its public IP address.

The Network Address Translation device translates the private IP addresses and port numbers of the devices in the private network to public IP addresses and unique port numbers when they communicate with the internet. This allows the devices to share a single public IP address and access the internet through a single connection.

Working of NAT 

When a device in a private network wants to communicate with a device on the internet, it sends a request to the NAT device (usually a router) with its private IP address and port number. The Network Address Translation device then translates the port number and private IP address to a public IP address and a unique port number and sends the request to the internet.

When the response is received from the internet, the Network Address Translation device translates the public IP address and port number back to the private IP address and port number and sends the response back to the device in the private network.

This process allows multiple devices in a private network to share a common (single) public IP address and access the internet through a single connection. It also hides the private IP addresses of the devices in the network, providing an additional layer of security.

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Network Address Translation is typically transparent to the devices in the network and does not require any configuration on the devices. However, some applications and network protocols may not work correctly with NAT, as they rely on end-to-end connectivity and may need help translating IP addresses and port numbers.

In such cases, it may be necessary to use a different type of NAT or to configure the application or protocol to work with Network Address Translation.

Here’s an image that explains the working of NAT in a better way:

As per the image above, only the Private IP (10.0.0.1) will be visible to the Internet. And, rest all other IP addresses, such as 10.0.0.4, 10.0.0.3, etc., will be hidden. 

Types of NAT 

There are several types of NAT, such as:

• Static NAT: This involves a one-to-one mapping between a private IP address and a public IP address. Each device in the private network is permanently mapped to a specific public IP address, allowing the device to be reached from the internet using the same public IP address every time.
• Dynamic NAT: This assigns a public IP address to a private IP address from a pool of available addresses. When a device in the private network wants to communicate with the internet, it is assigned a public IP address from the pool. When the connection is no longer needed, the public IP address is returned to the pool for use by another device.
• NAT with Port Address Translation (PAT): This allows multiple devices in a private network to share a single public IP address using different port numbers to distinguish between the different connections. When a device in the private network sends a request to the internet, the NAT device assigns a unique port number to the request. It also translates the port number and private IP address to the public IP address and the unique port number.
• NAT with Network Address and Protocol Translation (NAPT): This is similar to NAT with PAT, but it also translates the protocol used by the device. This allows devices that use different protocols, such as IPv4 and IPv6, to communicate with each other through the Network Address Translation device.

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Advantages of NAT

Some of the advantages of NAT are:

1. Conserves public IP addresses: Network Address Translation allows multiple devices in a private network to share a single public IP address, which helps to conserve the limited number of available public IP addresses.
2. Provides security: NAT conceals the private IP addresses of network devices, making it more difficult for attackers to target specific devices.
3. Simplifies network management: Network Address Translation allows devices in a private network to use non-unique private IP addresses. This simplifies network management by eliminating the need to obtain and assign unique public IP addresses to each network device.
4. Improves network performance: By allowing multiple devices to share a single internet connection, NAT can improve network performance. This reduces the number of internet connections required and can improve bandwidth utilization.
5. Increases flexibility: Network Address Translation allows devices in a private network to use private IP addresses that you can easily change without interfering with the devices’ connectivity. This increases network flexibility because adding or removing devices without reconfiguring the network or obtaining new public IP addresses is simple.

Disadvantages of Network Address Translation

Network Address Translation has the following drawbacks:

1. Complexity: NAT device translates the IP addresses and port numbers of the network’s devices; hence it increases the complexity factor of a network. 
2. Limited connectivity: Network Address Translation limits the connectivity of some devices and applications because it may not support all protocols or allow certain types of connections.
3. Reduced security: If NAT is not configured correctly or updated to address new threats, it can introduce security vulnerabilities.
4. Reduced performance: As Network Address Translation requires the NAT device to translate the IP addresses and port numbers of the network’s devices, it can reduce the performance of specific applications and protocols.

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To help you grasp what NAT is, here's an animated video by PowerCert:

Conclusion

After summarizing all the above information, NAT (Network Address Translation) is a method used by network devices in order to translate the IP addresses of devices in a private network to a single IP address. This single IP address is used to communicate with the internet. 

By doing so, Network Address Translation provides an additional layer of security by hiding the private IP addresses of the devices in the network. However, Network Address Translation can also introduce complexity, limit the connectivity of specific devices and applications, and decrease the performance of certain protocols. Hence, it should be configured appropriately and updated regularly in order to address new threats.

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Happy Learning!!