At 11:02 10/22/2003, webmaster wrote:

> >"192.168.0.1/28"        "WhiteList=1"
>
>This subnetting art confuses me.. What am I actually doing here?

That particular subnet designation would whitelist  8 addresses from 
192.168.0.0 - 192.168.0.15

You can look at it this way - IP addresses are, underneath everything, 
32-bit addresses. The /xx designation indicates how many of those 32 bits 
are significant.

/4 = look at only the first 4 bits
/8 = look at only the first 8 bits (first byte - normal class A address space)
/12 = look at only the first 12 bits
/16 = look at only the first 16 bits (two bytes - normal class B address space)
/24 = look at only the first 24 bits (three bytes - normal class C address 
space)
/28 = look at only the first 28 bits
/32 = look at *all* the bits

So, using 192.168.0.1 as an example,

192.168.0.1/4 = 192.0.0.0 - 207.255.255.255
192.168.0.1/8 = 192.0.0.0 - 192.255.255.255
192.168.0.1/12 = 192.160.0.0 - 192.175.255.255
192.168.0.1/16 = 192.168.0.0 - 192.168.255.255
192.168.0.1/24 = 192.168.0.0 - 192.168.0.255
192.168.0.1/28 = 192.068.0.0 - 192.168.0.15
192.168.0.1/32 = 192.168.0.1

You can specify any number of bits after the slash, although some places 
use only 4, 8, 12, 16, 20, 24, 28, and 32.


-
To unsubscribe from this list: send the line "unsubscribe xmail" in
the body of a message to [EMAIL PROTECTED]
For general help: send the line "help" in the body of a message to
[EMAIL PROTECTED]

Reply via email to