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List:       firewalls-gc
Subject:    Re: Reserved IP addresses.
From:       "Magossa'nyi A'rpa'd" <mag () bunuel ! tii ! matav ! hu>
Date:       1997-06-29 10:21:03
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On Fri, 27 Jun 1997, Wong wrote:

> Now we would like to add a new subnet into our LAN, either 172.18.51.0 (255.255.255.0) or
> 172.18.151.0 (255.255.255.0). Can you guys please tell me which block of IP address
> is reserved, except fot 127.0.0.0 (loopback), which is a well-known reserved address. 
> I would like to know which block is reserved for the Internet, or does it matter, since
> we are using a proxy?
Technically you could use any IP address range, as far as you are doing NAT.
I recommend using the reserved ranges though, as you won't be able to access
the machines those adresses really belong to. (/FUN What if you use
207.68.x.x internally, on which range www.microsoft.com resides. Good idea!
/ENDFUN)
Using the loopback range is definitely not a good idea. If the IP stack of
your  machine is well-written, do not  even think it will go  through.

From the rfc1597:

   The Internet Assigned Numbers Authority (IANA) has reserved the
   following three blocks of the IP address space for private networks:

        10.0.0.0        -   10.255.255.255
        172.16.0.0      -   172.31.255.255
        192.168.0.0     -   192.168.255.255

   We will refer to the first block as "24-bit block", the second as
   "20-bit block, and to the third as "16-bit" block.  Note that the
   first block is nothing but a single class A network number, while the
   second block is a set of 16 contiguous class B network numbers, and
   third block is a set of 255 contiguous class C network numbers.

---
GNU GPL: csak tiszta forrásból

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