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Date:      Wed, 21 Mar 2001 09:49:30 +0000
From:      Paul Richards <paul@freebsd-services.co.uk>
To:        Daniel Hagan <dhagan@colltech.com>
Cc:        Mark Murray <mark@grondar.za>, freebsd-audit@FreeBSD.ORG
Subject:   Re: ipfw permanent rules
Message-ID:  <3AB8792A.19308025@freebsd-services.co.uk>
References:  <3AB857E7.D4CEBD40@freebsd-services.co.uk> <200103210738.f2L7cof42204@gratis.grondar.za> <3AB85B6F.32E9EE7C@freebsd-services.co.uk> <3AB87590.FA684AE7@colltech.com>

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Daniel Hagan wrote:
> 
> > It sets a rule number below which rules will not be flushed. I've been
> > using it to install permanent rules, like SSH access from the office to
> > remote servers, so I can flush the majority of rules but keep those that
> > are essential to allow me to maintain connectivity to the box.
> 
> I'm a little concerned that this overrides the meaning of the rule
> numbers.  Now they will define what order rules are processed and
> whether they can be flushed.  Wouldn't it be more orthogonal to add a
> flag to each rule (like the log keyword) to mark permanent rules?  I
> don't know anything about the ipfw code, so maybe this is impractical
> (and I'm sure it would require more work), but it sounds worth it to me.

The order of rules processing isn't affected unless you enable this
feature. If you set the rule number above 0 then after a flush all the
presistent rules will be at the front of the chain so in that situation
it's possible for the rule order to get changed when you add back
flushed rules but if you're using this feature then you're going to have
your persistent rules together at the bottom of the number range anyway
so the problem shouldn't arise.

I looked at making it a per-rule setting but the flags field looks full
so it would require extending the struct and modifying the userland
parser. That was too much of a change for what I needed but I might take
a look at extending the functionality later.

Paul.

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