Published: 17/01/2022

Network Address Translation (NAT)

What is network address translation (NAT)?

Network Address Translation is a process that allows an entire network consisting of computers and devices to communicate safely even if they’re using private IP addresses, which aren’t unique since they only identify the home network instead of the individual device.

The term NAT can also be used as a blanket phrase describing several different types of Network Address Translation such as PAT, Cone NAT, and Static NAT.

How it works

NAT works by rewriting IP address information of outbound traffic so that it can match up to an internal IP address on the receiving device.

For example, if you have multiple devices at home sharing the same internet connection (and thus the same IP address) they can all communicate with each other via NAT.

On top of that, NAT can also use port forwarding to forward specific ports from the internet to specific devices on the home network.

Types of NATs

Network Address Translation comes in various forms and types:

  • Basic NAT. One-to-one (one device with one IP) allows for multiple internal devices to communicate via one external IP address.
  • Port Address Translation (PAT). Combines basic NAT with Port Address Translation, allowing for multiple external addresses to be mapped to a single public IP or multiple public Ips, which map back to a single computer or device within the private network.
  • Static NAT. This variation forces all traffic coming from a specified source address through an unaltered mapping to a specific destination address.
  • Dynamic NAT. This variation requires all outbound traffic to be mapped with a source and destination address that is different than the private IP addresses used in-house.

Frequently asked questions about network address translation (NAT)?

Who uses NAT?

Network Address Translation is most commonly used by ISPs that assign their customers private IP addresses instead of public ones.

How many devices does NAT support?

Regarding home networks, there are no limits imposed on the number of devices using NAT since they’re all behind a single external IP address shared via PAT (which allows multiple connections through a single IP address at a time).

In cases where many people are sharing a single IP address via NAT, the connection may become unstable due to congestion on the ISP’s proxy server or if multiple devices are trying to establish connections at the same time.

How is NAT different from port forwarding?

Network Address Translation only changes the source IP address (for internal communication) and forwards all packets to another computer on the network. Port forwarding, also known as port mapping, allows a user connected to a home network via NAT to remotely access services such as FTP, HTTP, or SSH running behind a router.

What is the difference between static and dynamic NAT?

In static Network Address Translation, systems connected within a private network can be accessed by other internet users using their own unique public IP addresses even if those devices aren’t communicating with each other at that time. This isn’t possible in dynamic Network Address Translation where the source and destination systems must be communicating for this type of Network Address Translation to take place.

How does NAT affect games?

In some cases where two players are using private IP addresses within separate home networks, NAT can be used to connect them via a third party, such as a router’s built-in servers that translate the packets received from both players.

In other cases, Network Address Translation may need to be turned off in order for online games to work properly.

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