ipfw matching

2002-11-12 Thread Mark 
I have a quick question on the way ipfw matches IP masks. If I give this IP
address:

12.144.51.128/17

Am I then correct in thinking it will match all IP addresses from
12.144.51.128 to 12.144.51.255? Or will it start matching from 12.144.51.0?
(not what I want).

Now for the harder question (I guess there is a second question, after all).
If I want to match from 12.51.0 to 12.51.15 (and all their hosts
underneath), would I write this:

12.51.0.0:255.255.240.255 ?

I really wanna crack down on some spammers, but not waste too many ipfw
rules on it.

Thanks!

- Mark


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ipfw matching (revisited)

2002-11-12 Thread Mark 
Ok, I constructed the following IP:mask for ipfw to match:

202.43.64.0:255.255.191.0

This is supposed to match the range 202.43.64.xx to 202.43.127.xx

Will this happen? It is really important that it does not match too much.

Thanks!

- Mark


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Re: ipfw matching (revisited)

2002-11-12 Thread Matthew Seaman 
On Tue, Nov 12, 2002 at 03:06:42PM +0100, Mark wrote:
 Ok, I constructed the following IP:mask for ipfw to match:
 
 202.43.64.0:255.255.191.0
 
 This is supposed to match the range 202.43.64.xx to 202.43.127.xx

Close, but no cigar.  You want:

202.43.64.0:255.255.192.0  also known as 202.43.64.0/18
  ^

That matches the addresses from 202.43.64.0 to 202.43.127.255
inclusive.

Cheers,

Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.   26 The Paddocks
  Savill Way
  Marlow
Tel: +44 1628 476614  Bucks., SL7 1TH UK

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Re: ipfw matching (revisited)

2002-11-12 Thread Mark 
- Original Message -
From: Matthew Seaman [EMAIL PROTECTED]
To: [EMAIL PROTECTED]
Sent: Tuesday, November 12, 2002 3:45 PM
Subject: Re: ipfw matching (revisited)


 On Tue, Nov 12, 2002 at 03:06:42PM +0100, Mark wrote:
  Ok, I constructed the following IP:mask for ipfw to match:
 
  202.43.64.0:255.255.191.0
 
  This is supposed to match the range 202.43.64.xx to
  202.43.127.xx

 Close, but no cigar.  You want:

 202.43.64.0:255.255.192.0  also known as 202.43.64.0/18
  ^

 That matches the addresses from 202.43.64.0 to 202.43.127.255
 inclusive.


Thanks for the explanation. Yes, 191 (1011) would only have bit 6
variable; indeed, I needed 192 (1100), to keep the lower 6 bits
variable. It is clear to me now.

Good thing I asked! :)

- Mark


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