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On 29 Sep 2004, at 11:08, NetHead wrote:
For example, 218.175.0.0/16... how do I interpret that? I have read some
of the RFC's on CIDR notation, but it still boggles my mind. Would that
mean that they own the entire range from 218.175.0.0-218.175.254.254?
Exactly right.
Is there an easy way to read CIDR? or a tool that will do the conversion?
There are a bazillion pages on google that will calculate CIDRs and netmasks for you. It is pretty easy to do yourself.
218.175.0.0 is
11011010.10101111.00000000.00000000
/16 is
11111111.11111111.00000000.00000000 (first 16 bits are ON)
this means that anything in the address that is masked (has a 1 in the netmask) does not change, so the range is
11011010.10101111.00000000.00000000-11011010.10101111.11111111.111111111
if their address range was, say, /18 then the range would be:
11011010.10101111.00000000.00000000-11011010.10101111.00111111.11111111 (218.175.0.0-218.175.63.255
if the address was a /24 then the range would be:
11011010.10101111.00000000.00000000-11011010.10101111.00000000.11111111 (218.175.0.0-218.175.0.255)
/8 is a Class A address, /16 is a Class B, and /24 is a Class C. A Class C, of course, has 256 IPs in it. A class B has 256^2 IPs (65536) and a class A has 256^3 IPs in it (16,777,216). The entire IP address range contains 256^4 IPs (about 4.3 billion addresses).
--
"Let's get back to syntax of procmail and forget the syntax of fools." - Don
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