What does nat do

This helps to keep more public IP addresses available even while private IP addresses proliferate. It will take many years before this process finishes; so until then, NAT will be a valuable tool. A wide area network WAN is a large network of not tied to a single location. WANs allows devices from around the world to communicate and share information. A local area network LAN is a series of computers linked together to form a network in a circumscribed location.

Additionally, NAT can provide security and privacy. Because NAT transfers packets of data from public to private addresses, it also prevents anything else from accessing the private device.

The router sorts the data to ensure everything goes to the right place, making it more difficult for unwanted data to get by. NAT also allows you to display a public IP address while on a local network, helping to keep data and user history private. This type of NATTING scheme is usually used for servers requiring the same IP address always, hence the name "static", so server 1 will always have the same IP address assigned to it, server 2 will have a different public IP address assigned to it and so on.

This time though the pool of IP addresses will be used when needed and then given back to the pool. So if computer A needed a public address, it would take one from the pool, then hand it back when done. The next time the same computer wanted an IP address it may be assigned a different public address from the pool, because the one used previously may be in use by another computer, hence the name "dynamic". So users who want to communicate on the internet at any one time will be limited by how many public IP addresses are available in the NAT pool.

A company would purchase a number of public IP's depending on their need. In this type of setup, a company would only have one public IP address assigned to their network, and so everyone would share this one public address when using the internet, browsing the web for example.

Yes, you may be asking how can everyone share one address, well the clue lies within the name, Port address translation. For example The NAT device will keep a note of this, and when Amazon replies to the public address and the port number of , the NAT device will use the PAT method and look up the port information which maps to the internal computer requesting it. So it would be saying, this information Amazon has sent back to the public address and port number , maps to the IP address So the connections are uniquely identified by a source port, all using the same public IP but with unique source ports to identify who requested what information.

A company would save a reasonable amount of money and IP addresses using this method because it is only using one IP address. This has been a major factor to why IPv6 has been mentioned for some years now but still not required in most countries. If NAT runs out of addresses, i. Skip to content. Change Language. Related Articles. Computer Network Fundamentals. Physical layer. Data Link layer. Network layer. Transport layer. Network address translation permits a single device, such as a NAT firewall or NAT router or other network address translation device, to act as an agent between the public network and private networks—the internet and any local networks.

This allows an entire group of devices to be represented by a single unique IP address when they do anything outside their network. They tell the receptionist they need to speak with you, and the receptionist a checks the instructions and knows you want the call forwarded, and b matches your extension with a list to send the information to the right place.

The caller never gets your private line. Network address translation works similarly. The request arrives at the public IP address and port, and the NAT instructions send it where it should go without revealing the private IP addresses of the destinations. As a NAT network address translation example, an inside host may want to communicate with a destination network address translation web server address in the outside world. The NAT gateway router determines whether the packet meets the condition for translation by learning the source IP address of the packet and looking it up in the table.

It can locate authenticated hosts for the internal network translation purposes on its access control list ACL , and then complete the translation, producing an inside global IP address from the inside local IP address. Finally, the NAT gateway router will route the packet to the destination after saving the translation in the NAT table. Referring back to the NAT table, the router can determine which translated IP address corresponds to which global address, translate it to the inside local address, and deliver the data packet to the host at their IP address.

The data packet is discarded if no match is found. Static network address translation SNAT. It is particularly useful when a device needs to be accessible from outside the network.

Dynamic network address translation DNAT. This form of NAT selects a target from a group of registered IP addresses and maps an unregistered IP address to the registered version.

Reverse network address translation RNAT. RNAT allows users to connect to themselves using the internet or public network.

Overloading network address translation NAT. In terms of port address translation vs network address translation, PAT is often most cost-effective when many users are connected to the internet through just one public IP address. Overlapping network address translation NAT. Overlapping NAT can happen either when two organizations whose networks both use RFC IP addresses merge, or when registered IP addresses are assigned to multiple devices or otherwise in use on more than one internal network. In both cases, the networks need to communicate, and the organization s use overlapping NAT to achieve this without readdressing all devices.

The NAT router intercepts addresses, and maintains a table of them so that it can replace them with registered unique IP addresses. The network address translation router must both translate registered external IP addresses to those unique to the private network and translate internal IP addresses to registered unique addresses. In the network address translation context, the internal network, commonly referred to as the stub domain, is usually a local area network LAN that uses IP addresses internally.

Most stub domain network traffic is local, remaining inside the internal network. A stub domain may include both unregistered and registered IP addresses. A traditional NAT configuration requires at least one interface on a router NAT outside ; another interface on the router NAT inside ; and a configured set of rules for translating the IP addresses in the packet headers and possibly payloads. In this example of network address translation configuration, IT configures the NAT router as follows.

Whenever a device on the inside with an unregistered inside, local IP address needs to communicate with the outside, public network, the router translates those unregistered addresses residing on the private inside network to registered IP addresses.

Multiplexing enables a computer to maintain multiple connections with remote computer s concurrently using different ports.