Re: IP range to CIDR list VB6 utility?
From: Stefan Berglund (keepit_at_in.thegroups)
Date: 09/20/04
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Date: Mon, 20 Sep 2004 10:31:51 -0700
On Mon, 20 Sep 2004 04:56:16 GMT, "WinGuy" <no_spam@nomail.bot>
wrote:
in <Qpt3d.21577$mn7.20635@newssvr27.news.prodigy.com>
>"Jim Carlock" <anonymous@127.0.0.1> wrote in message
>news:uN3Y8arnEHA.1800@TK2MSFTNGP15.phx.gbl...
>> Where did you get your list of IP numbers from ?
>>
>> Usually folks get a block, something like a class B set of
>> IP numbers or a class C set if they're providing webhosting.
>>
>> If it's for an internal LAN, you don't need to buy such blocks,
>> you'll only need one IP number and then configure the internal
>> network on a 192.168.... or 10..... subnet.
>>
>> Class A:
>> 217.224.0.0/8 -> 217.0.0.0 to 217.255.255.255, or
>> Class B:
>> 217.224.0.0/16 -> 217.224.0.0 to 217.224.255.255, or
>> Class C:
>> 217.224.0.0/24 -> 217.224.0.0 to 217.224.0.255
>>
>> I see the following:
>>
>> route: 217.224.0.0/11
>> descr: Deutsche Telekom AG, Internet service provider
>> origin: AS3320
>> member-of: AS3320:RS-PA-TELEKOM
>>
>> You buy a block of numbers from these guys?
>>
>> --
>> Jim Carlock
>> http://www.microcosmotalk.com/
>> Post replies to the newsgroup.
>
>No, Jim, that was just an example IP range I was using because it's real but
>allocated strangely. The real purpose of the VB project was explained
>already in my post that opened this topic. That example IP address range is
>easy to block by IP range, but difficult to block based on CIDR or netmask
>methods. I've already built and have running a transparent (it's NIC's have
>no IP addresses) statefull firewall FreeBSD box dedicated to running only
>one thing, a firewall called IP Filter (aka IPF), and its filter rules
>require using CIDR instead of ranges. It sits immediately inline with a
>broadband modem, a hub is on the other side of IPF and everything else
>connects to that hub (several routers, each having their own public IP
>address). It looks like this: WAN-Modem -> IPF -> Hub -> Routers -> LANS.
>
>There are actually 3 LAN's so far, all isolated from each other: wireless
>access point, server, and for the office. Main reason for the IPF box is to
>reduce and to eventually remove the firewall load on the server box. The
>server box itself has 2 firewalls (BlackIce and ZoneAlarm Pro) of its own,
>but the server cpu cycles and HDD activity is way excessive from time to
>time as it fends off attacks on its IIS web & ftp server or disallows
>spammers access to the email server (all are on the same box). So I built
>IPF to not only lighten the firewall cpu demands on the server but to also
>help protect all the other LAN's at the same time. So I've all these tables
>of IP addresses, and ranges of IP addresses, that have been a nuisance (or
>worse) in the past but the rules are in IP address range format and I have
>to convert them to CIDR format in order to move the rules over to the IPF
>box. That's why I'm trying to write the VB utility to help me with the
>rather large job that doing manually would take me forever. And I figure a
>utility that computes a CIDR list for any IP range is kind of a good idea
>beyond my current need for it!
>
>FWIW, Jim, that IP range I used for the example is indeed one of a great
>many that I block. I can tell by your interest that you probably know
>exactly why I block that entire ISP.
>
>I really appreciate any help this forum gives me to get this utility I'm
>trying to write working as soon as possible. I'll make it freely available
>in return.
One suggestion I'd make is to dump both BlackIce and ZoneAlarm
and get Kerio. I used to use ZoneAlarm until I watched Dark
Angel trojan take it out on every reboot. ZoneAlarm hardly
affords any protection. Kerio is a bit more complicated but you
sound like a guy who'd have no trouble setting it up. Oh, and
it's free!
--- Stefan Berglund
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