[X4U] What is NAT and what does it mean to me?

[Robert Ameeti]

At 3:21 PM -0700, 5/10/07, Eddie Hargreaves wrote:

>NAT is Network Address Translation
>
>Your ISP provides you with a single IP address, like 67.181.33.253 and if
>you want to hook up multiple devices to the Internet through that one
>connection, you use a router which provides those devices with different IP
>addresses like 10.0.1.2 and 10.0.1.3. That is NAT.

Nope, That is DHCP. (Dynamic Host Configuration Protocol)

NAT is where the router takes a single IP address (on the WAN (Wide 
Area Network) side) and then keeps track of multiple IP addresses on 
the LAN (Local Area Network) side and does the translation so that 
each of the multiple addresses can pass through the router out to the 
Internet using the single WAN IP address and then be able to receive 
the response coming back to the WAN IP address passing through the 
router and then back to the originating LAN address. The router keeps 
a routing table so that it knows which address on the LAN side needs 
to receive the incoming responses. Thus, it is translating the 
incoming responses to the correct internal address.

>When two devices on the same network try and distribute IP addresses 
>using NAT, it can cause problems.

If you are describing double NAT, then the above would not be 
addressing the issue.

Double NAT would be where the ISP's router was doing NAT and 
providing a 'network' of addresses and then one of the devices (your 
AirPort) hooked up to one of its ports was also doing NAT. It is not 
impossible to deal with but should be avoided when possible.
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Robert Ameeti

If you ain't got nothing, you've got nothing to lose.
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