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Date:      Mon, 28 Aug 2000 23:45:15 -0700
From:      "Crist J . Clark" <cjclark@reflexnet.net>
To:        Bruce Petro <bpetro@usa.com>
Cc:        freebsd-questions <freebsd-questions@FreeBSD.ORG>
Subject:   Re: ipfw setup when dhcp?
Message-ID:  <20000828234515.F62475@149.211.6.64.reflexcom.com>
In-Reply-To: <384197957.967500064518.JavaMail.root@web302-mc.mail.com>; from bpetro@usa.com on Mon, Aug 28, 2000 at 06:01:04PM -0400
References:  <384197957.967500064518.JavaMail.root@web302-mc.mail.com>

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[Could you add a newline from time to time? Your paragraphs are all on
one line.]

On Mon, Aug 28, 2000 at 06:01:04PM -0400, Bruce Petro wrote:
> Michael, thanks for the reply - yes, you have a good point, after I reviewed the contents of the rc.firewall that they had documented on http://www.mostgraveconcern.com/freebsd/ (The dual-homed host article - which is what I was going by), I see that the only use of the actual onet and omask and inet and imask was to perform the rules he titles: # Stop spoofing. (see details below). 
> 
> So, can anyone share is the #stop spoofing possible to do when you are under dhcp and not able to know ahead of time what your onet and omask are going to be?  I know inet and imask are static, and well, I guess you could assume the omask is pretty static, but still the onet address remains quite dynamic...
> 
> Any ideas?

I do,

  oip=`/sbin/ifconfig ${natd_interface} | /usr/bin/awk '/inet / { print $2 }'`
  oif=${natd_interface}
  obc=`/sbin/ifconfig ${natd_interface} | /usr/bin/awk '/inet / { print $6 }'`

To extract the interface and broadcast address. I didn't bother to
grab the mask, but it would be,

  omask=`/sbin/ifconfig ${natd_interface} | /usr/bin/awk '/inet / { print $4 }'`
-- 
Crist J. Clark                           cjclark@alum.mit.com


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