Date: Fri, 14 Nov 2008 01:10:07 -0800 From: Julian Elischer <julian@elischer.org> To: Ian Smith <smithi@nimnet.asn.au> Cc: FreeBSD Net <freebsd-net@freebsd.org>, ipfw@freebsd.org Subject: Re: rc.firewall quick change Message-ID: <491D406F.5030806@elischer.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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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..
> in fact it should be ${BLOCKTABLE} and let the user define what he
> wants. (defaulting to 99 or something).
> Remember though that a user wouldn't be using 'simple' if he's using his
> own tables etc.
>
so here's a slightly improved diff:
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Index: rc.firewall
===================================================================
--- rc.firewall (revision 184948)
+++ rc.firewall (working copy)
@@ -216,11 +216,13 @@
# firewall_simple_inet: Inside network address.
# firewall_simple_oif: Outside network interface.
# firewall_simple_onet: Outside network address.
+ # firewall_block_table: Table to use blocking stuff.
############
# set these to your outside interface network
oif="$firewall_simple_oif"
onet="$firewall_simple_onet"
+ tbl=${firewall_block_table:-99}
# set these to your inside interface network
iif="$firewall_simple_iif"
@@ -231,19 +233,24 @@
${fwcmd} add deny all from ${onet} to any in via ${iif}
# Stop RFC1918 nets on the outside interface
- ${fwcmd} add deny all from any to 10.0.0.0/8 via ${oif}
- ${fwcmd} add deny all from any to 172.16.0.0/12 via ${oif}
- ${fwcmd} add deny all from any to 192.168.0.0/16 via ${oif}
+ ${fwcmd} table ${tbl} add 10.0.0.0/8
+ ${fwcmd} table ${tbl} add 172.16.0.0/12
+ ${fwcmd} table ${tbl} add 192.168.0.0/16
# Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
# DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
# on the outside interface
- ${fwcmd} add deny all from any to 0.0.0.0/8 via ${oif}
- ${fwcmd} add deny all from any to 169.254.0.0/16 via ${oif}
- ${fwcmd} add deny all from any to 192.0.2.0/24 via ${oif}
- ${fwcmd} add deny all from any to 224.0.0.0/4 via ${oif}
- ${fwcmd} add deny all from any to 240.0.0.0/4 via ${oif}
+ ${fwcmd} table ${tbl} add 0.0.0.0/8
+ ${fwcmd} table ${tbl} add 169.254.0.0/16
+ ${fwcmd} table ${tbl} add 192.0.2.0/24
+ ${fwcmd} table ${tbl} add 224.0.0.0/4
+ ${fwcmd} table ${tbl} add 240.0.0.0/4
+ # Stop the above nets with the table
+
+ ${fwcmd} add deny all from any to "table(${tbl})" via ${oif}
+
+
# Network Address Translation. This rule is placed here deliberately
# so that it does not interfere with the surrounding address-checking
# rules. If for example one of your internal LAN machines had its IP
@@ -260,19 +267,8 @@
esac
# Stop RFC1918 nets on the outside interface
- ${fwcmd} add deny all from 10.0.0.0/8 to any via ${oif}
- ${fwcmd} add deny all from 172.16.0.0/12 to any via ${oif}
- ${fwcmd} add deny all from 192.168.0.0/16 to any via ${oif}
+ ${fwcmd} add deny all from "table(${tbl})" to any via ${oif}
- # Stop draft-manning-dsua-03.txt (1 May 2000) nets (includes RESERVED-1,
- # DHCP auto-configuration, NET-TEST, MULTICAST (class D), and class E)
- # on the outside interface
- ${fwcmd} add deny all from 0.0.0.0/8 to any via ${oif}
- ${fwcmd} add deny all from 169.254.0.0/16 to any via ${oif}
- ${fwcmd} add deny all from 192.0.2.0/24 to any via ${oif}
- ${fwcmd} add deny all from 224.0.0.0/4 to any via ${oif}
- ${fwcmd} add deny all from 240.0.0.0/4 to any via ${oif}
-
# Allow TCP through if setup succeeded
${fwcmd} add pass tcp from any to any established
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