Date: Fri, 9 Aug 2013 18:34:41 +0200 From: Fleuriot Damien <ml@my.gd> To: Peter Wemm <peter@wemm.org> Cc: FreeBSD Net <freebsd-net@freebsd.org>, s m <sam.gh1986@gmail.com> Subject: Re: how calculate the number of ip addresses in a range? Message-ID: <8B53C542-5CC3-45E6-AA62-B9F52A735EE5@my.gd> In-Reply-To: <CAGE5yCoBYS2%2BsHoQXZvWMNPTQeEEtDX7LAKSBHJAZ4_rA2-byQ@mail.gmail.com> References: <CAA_1SgEEeyCOk%2Bi9Zp725RfQ9s0tpELXL0SSBeiN%2B60z%2BxqYUg@mail.gmail.com> <CAGE5yCoBYS2%2BsHoQXZvWMNPTQeEEtDX7LAKSBHJAZ4_rA2-byQ@mail.gmail.com>
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On Aug 8, 2013, at 10:27 AM, Peter Wemm <peter@wemm.org> wrote:
> On Thu, Aug 8, 2013 at 12:04 AM, s m <sam.gh1986@gmail.com> wrote:
>> hello guys,
>>=20
>> i have a question about ip addresses. i know my question is not =
related to
>> freebsd but i googled a lot and found nothing useful and don't know =
where i
>> should ask my question.
>>=20
>> i want to know how can i calculate the number of ip addresses in a =
range?
>> for example if i have 192.0.0.1 192.100.255.254 with mask 8, how many =
ip
>> addresses are available in this range? is there any formula to =
calculate
>> the number of ip addresses for any range?
>>=20
>> i'm confusing about it. please help me to clear my mind.
>> thanks in advance,
>=20
> My immediate reaction is.. is this a homework / classwork / =
assignment?
>=20
> Anyway, you can think of it by converting your start and end addresses
> to an integer. Over simplified:
>=20
> $ cat homework.c
> main()
> {
> int start =3D (192 << 24) | (0 << 16) | (0 << 8) | 1;
> int end =3D (192 << 24) | (100 << 16) | (255 << 8) | 254;
> printf("start %d end %d range %d\n", start, end, (end - start) + 1);
> }
> $ ./homework
> start -1073741823 end -1067122690 range 6619134
>=20
> The +1 is correcting for base zero. 192.0.0.1 - 192.0.0.2 is two
> usable addresses.
>=20
> I'm not sure what you want to do with the mask of 8.
>=20
> You can also do it with ntohl(inet_addr("address")) as well and a
> multitude of other ways.
Hold on a second, why would you correct the base zero ?
It can be a valid IP address.
=
https://labs.ripe.net/Members/stephane_bortzmeyer/all-ip-addresses-are-equ=
al-dot-zero-addresses-are-less-equal
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