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Date:      Wed, 23 Sep 1998 17:34:20 +0800
From:      Peter Wemm <peter@netplex.com.au>
To:        Studded <Studded@dal.net>
Cc:        Drew Baxter <netmonger@genesis.ispace.com>, rotel@indigo.ie, FreeBSD Hackers <hackers@FreeBSD.ORG>
Subject:   Re: Packet/traffic shapper ? 
Message-ID:  <199809230934.RAA14233@spinner.netplex.com.au>
In-Reply-To: Your message of "Wed, 23 Sep 1998 00:37:29 MST." <3608A539.B9BD103E@dal.net> 

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Studded wrote:
> Drew Baxter wrote:
> > 
> > At 12:49 AM 9/23/98 +0000, Niall Smart wrote:
> > >
> > >Personally I don't think IPFW_DEFAULT_TO_ACCEPT is a bad idea, once you
> > >are sure you have the accept rules necessary to ensure your connectivity
> > >to the host you can pop in a deny all rule.  This will probably be slower
> > >than defaulting to deny though.
> > ---
> > Hm, isn't default_to_accept still affected by ipfw flush?
> 
> 	No it's not, that's one of the reasons the option was added.

The other reason it's an option is because it's a tradeoff situation.  An
inclusive filter (ie: only explicitly allow defined packets) is compromised
if an accident happens or somebody can make the box fall over and somehow
not reload it's filters properly.

With an exclusive strategy (eg: ISP, who is in the business of carrying 
data rather than dropping it), it's beneficial to have it open by default 
so that specific things can be filtered when and as needed without the 
risk of accidents closing everything down.

Generally, accidently leaving the barn door open and everything running
away generally is far worse than having to drive to fix the damn thing.

"Generally" is the key.  One policy doesn't always fit everybody perfectly,
but having it this way seems the lesser of the evils.

> Doug

Cheers,
-Peter
--
Peter Wemm <peter@netplex.com.au>   Netplex Consulting
"No coffee, No workee!" :-)



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