On Thursday 07 August 2003 02:12 pm, Kurt Granroth wrote:
> AND the IP address with the mask
> C0A80164 & FFFF0000 = C0A80000
>
> AND the network with the mask
> C0A80000 & FFFF0000 = C0A80000
On further recollection, this step isn't necessary. Just compare the IP
address ANDed with the netmask with the network IP.
Also, that means that given any IP address and a netmask, you can compute what
network it's on.
192.168.127.25/18 is on network 192.168.64.0, for instance
C0A87F19 & FFFFC000 = C0A84000 (192.168.64.0)
I also did a very quick search on google and found the following two utilities
that do the conversion for you. Perhaps you can use them as a code example:
http://lpccomp.bc.ca/netmask/netmask.c
http://jabber.mpsnet.net.mx/ftp/linux/misc/ipcalc.pl
(text/plain)