Date: Fri, 14 Nov 2008 21:21:55 +1100 (EST) From: Bruce Evans <brde@optusnet.com.au> To: Julian Elischer <julian@elischer.org> Cc: FreeBSD Net <freebsd-net@FreeBSD.org>, ipfw@FreeBSD.org, Ian Smith <smithi@nimnet.asn.au> Subject: Re: rc.firewall quick change Message-ID: <20081114211043.W54700@delplex.bde.org> In-Reply-To: <491D375D.1070809@elischer.org> References: <491CD94F.3020207@elischer.org> <20081114133913.K70117@sola.nimnet.asn.au> <491D375D.1070809@elischer.org>
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On Fri, 14 Nov 2008, Julian Elischer wrote:
> Ian Smith wrote:
>> On Thu, 13 Nov 2008, Julian Elischer wrote:
>> > At home I use the following change.
>> > > > basically, instead of doing 8 rules before and after the nat,
>> > use a table and to 1 rule on each side.
>> > > > any objections?
>>
>> Only that if people are already using tables for anything, chances are
>> they've already used table 1 (well, it's the first one I used :) How about
>> using table 127 for this as a rather less likely prior choice?
>
> yes I thought of that..
Separate rules provide more statistics.
> in fact it should be ${BLOCKTABLE} and let the user define what he wants.
> (defaulting to 99 or something).
I use shell variables giving lists of interfaces to be blocked so that
there aren't very many rules:
%%%
rfc1918n=10.0.0.0/8,172.16.0.0/12,192.168.0.0/16
dmanningn=0.0.0.0/8,169.254.0.0/16,192.0.2.0/24,224.0.0.0/4,240.0.0.0/4
${fwcmd} add deny log all from any to ${rfc1918n} via ${oif}
${fwcmd} add deny log all from any to ${dmanningn} via ${oif}
... (divert rule)
${fwcmd} add deny log all from ${rfc1918n} to any via ${oif}
${fwcmd} add deny log all from ${dmanningn} to any via ${oif}
%%%
I use separate lists mainly for documentation purposes but they also
provide separate statistics.
> Remember though that a user wouldn't be using 'simple' if he's using his own
> tables etc.
Separate rules are also simplest for documentation purposes.
>> Apart from that, this will speed up 'simple' on a path every packet takes,
>> which has to be a good thing.
Are tables faster than lists of addresses? I would expect lists to be
slightly more efficient.
Bruce
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