Network Address Translation

A Basic Primer into Networking

Steve Smith explains the basic premise of Network Address Translation and how it allows many computers to share a single IP address.

Episode #3-46 released on August 11, 2013

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Today, we owe much of our homes entertainment options to NAT, or Network Address Translation. Without it, the internet, and our experience of the internet, would not be the same. If Network Address Translation was not implemented at the home network level, we may not have online gaming, we may not have networks of computers, mobile devices, we wouldn't have a network, period.

What is NAT and what does it do?

Network Address Translation is basically self explanatory, it is the process of transparently modifying IP addresses in packet headers while in transit across the routing device, your router.

For file sharing within networks, accessing the internet with many devices, etc..., we use routers. Routers provide an essential service, and provide security. Routers use NAT, and in turn prevent any unauthorized, or unrequested access to the network from the outside. For the entire internet, your network appears as one distinct device with a single unique IP address. You router has a lot of work to do to make everything flow correctly. Each device in the network has their own unique IP address inside the network, which is changed when leaving the network when heading over to the internet. Then the router has to wait for a reply, which is sends back to the originating device with the help of the translation table.

The contents of the translation table are basically of list of outgoing connections from specific devices, sent over unique ports, often referred to as something like a post office box number. When the connection is returned, the NAT router looks at the translation table for a match, if one is found, it redirects transparently the data to the device that requested the data in the first place. If no match is found, the connection is ignored and dropped.

For more information of NAT, I suggest reading the Wikipedia article for the specific NAT types and their sources.

Next week, I will be talking about alternative domain name servers that may be of use for anyone who has ever used a slow or unreliable DNS server from their router manufacteur or internet service provider.

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Host : Steve Smith | Music : Jonny Lee Hart | Editor : Steve Smith | Producer : Zed Axis Productions

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