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What is NAT?

Garry Crystal
Garry Crystal

At the moment, there are thought to be around 100 million hosts and 350 million users actively using the Internet. This number is doubling each year. An Internet Protocol (IP) address is needed for computers to communicate with other computers or web servers. IP works by finding out exactly where your computer is and sending information to you.

The actual number of IP addresses available is around 3.3 billion. With the huge growth in the Internet, there are simply not enough addresses available. This is where Network Address Translation (NAT) comes into play. It allows a single device to act as an intermediary between the Internet and a local network. This effectively means that a single IP address can be used for an entire group of computers.

A NAT can direct an unregistered IP address to a registered one.
A NAT can direct an unregistered IP address to a registered one.

NAT was developed by Cisco. It is used by an appliance, such as a computer or firewall, which sits between an internal network and the outside world of networks. The NAT works in many different ways. There is the Static NAT, which directs an unregistered IP address to a registered IP address. This is very useful when a computer needs to access another computer from outside the network.

There is also the Dynamic NAT, which directs unregistered IP addresses to registered ones from a collective of registered IP addresses. NAT can also use overloading, whereby multiple unregistered IP addresses are directed to a single address using various ports. Each computer on the private network uses the same address but is given a different port number. Basically, the port is an extension of the IP address.

Most businesses that have computers connected to the Internet use NAT. A University, for example, can have hundreds of computers installed for both staff and students. With the advent of the Internet café and online gaming establishments, there is a greater need than ever for the NAT. Think of the NAT as the first port of call when another computer is trying to access yours via the Internet. This computer will "ask" the NAT to be put through to you instead of contacting you directly.

At the moment, there is a system under development that is redesigning IP addresses. Called Ipv6, it will not be available for several years because the entire structure of the Internet will need to be modified. At the moment, then, NAT is the best and safest method we have to enable computers to talk to each other.

Discussion Comments

anon943645

Why couldn't the use of NAT be sufficient?

papasmurf

My PS3 says that my NAT is too strict for playing ps3 games online. How can i change this?

anon206306

how is nating done on a windows machine?

anon154041

I was trying to play Halo: Reach with my friends and it said I couldn't join at first because my NAT is moderate (don't know if it's open or not) so can you help me please?

anon137690

I have an Xbox 360 that says the NAT needs to be open instead of strict. I have tried to pull up my routers web page and turn the NAT to open but it says it is already open. How do i change this problem?

thespica93

My NAT type is strictly on xbox 360. i can fix it by typing in my default gateway into a web browser. It asks me for a password on the web page. I don't remember the password. Can you help me reset it. Thanks

anon118751

Great article up until the point you started talking about unregistered IP addresses.

Then you lost me. So I'm afraid I don't understand what an NAT is beyond the fist two paragraphs of an explanation: It's a box that allows people to share an IP address. And it has something to do with whether you your IP address is registered or not.

anon68415

"i have a standby server and main server...internet connection is to standby server...i don't have static public address for internet connection...

i want to share the internet connection wt clients tat are connected to main server...how do i do this?"

Answer: It's so simple. You just need to set the default gateway of clients as an ip server.

for example if your server ip is 192.168.1.1 you should put this in default gateway of each client.

anon60649

to anon37399: please tell us the name and make of your router.

Some family routers (for example the BTHomeHub) have no way of changing the NAT setting. However, many unchangeable routers automatically download updates which change them to STRICT NAT settings. A way around this is to reset your router every week, it's a bit time consuming but it changes your NAT to open.

anon37399

I have an Xbox 360 that says the NAT needs to be open instead of strict. I have tried to pull up my routers web page and turn the NAT to open but it says it is already open. How do i change this problem?

anon28912

i have a standby server and main server...internet connection is to standby server...i don't have static public address for internet connection...

i want to share the internet connection wt clients tat are connected to main server...how do i do this?

sreedhar

How can I connect Many servers by using a single static IP address? To give online access to my students who are located across the world and learning different software & IT technologies through our company. And I think you know that it is not possible to keep all of them in one server as they are designed with different programming languages or scripts or functionality or formats.

pandoranet

I have a separate voice network and a separate data network, from last few weeks i am having issues with my voice network and the service provider asks me to disable the NAT on the voice network, as they say that they are doing the NATing at the server end, i would like to know is this possible. Will the internet work if i disable the NAT?

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    • A NAT can direct an unregistered IP address to a registered one.
      By: iinspiration
      A NAT can direct an unregistered IP address to a registered one.