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Re: NAT addresses - RFC or tradition?

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Subject: Re: NAT addresses - RFC or tradition?
From: Grant Taylor <gtaylor@riverviewtech.net>
Date: Tue, 22 May 2007 15:22:50 -0500
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On 05/22/07 14:26, Paul Blondé wrote:
I've noticed that a lot of people use the 192.168.X.X subnet for internal networks, is this (and the less-used 10-series) a requirement of some RFC, or a recommendation that has become tradition?

10.0.0.0-10.255.255.255, 172.16.0.0-172.31.255.255, and 192.168.0.0-192.168.255.255 are reserved for private (read internal) use and guaranteed to not be globally routable. As others have stated, you can use any address you want, though you run the risk of being in conflict with some subnet somewhere. Granted it is VERY unlikely that you will effect any one other than your self as the world will route to the other subnet, not you.

Please reference RFC 3330 - "Special-Use IPv4 Addresses" (http://www.rfc-editor.org/rfc/rfc3330.txt) for more information on these and other reserved subnets.

We are using a completely different subnet, something similar to (for example) 42.127.129.X to further obfuscate the internal network from outside. This, and many other examples, produces a class-A subnet mask (some produce a class-B) when entered in WinXP's TCP/IP dialog, although the actual mask we use with it is class-C.

*nod*

Is this a no-no? Will it break our server's IPTables when communicating with it? Am I in for a lot of trouble? The addresses don't seem to cause any problems, but I don't want this to jump up and bite us in the bottom sometime down the road.

Well, the 42.x.y.z is not too bad as far as conflicting with someone else seeing as how IANA has it "Reserved". Take a look at the "Internet Protocol v4 Address Space" page (http://www.iana.org/assignments/ipv4-address-space) on IANA's web site for more information.



Grant. . . .


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