On 21/05/2012 16:44, Michael Sierchio wrote:
On Mon, May 21, 2012 at 8:30 AM, Paul Macdonald<p...@ifdnrg.com> wrote:
A very open firewall test script is as follows:
00010 allow ip from any to any via lo0
00081 deny log ip from 180.0.0.0/8 to any
00100 check-state
You don't need the following
00101 allow tcp from any to any established
This may not do what you think - "out" does not necessarily mean out
your external interface. Packets can go in and out (from the
perspective of the ruleset) more than once. And you want only to
start a dynamic rule for legitimate TCP traffic, which means "tcpflags
syn,!ack" - See below
00102 allow ip from any to any out keep-state
and you probably want to be selective about which ICMP you allow
00103 allow icmp from any to any
65535 deny ip from any to any
It's also helpful (most of the time) to be explicit about the interface
Is this ruleset just protecting this host itself, or are you using it
as a firewall for an internal network?
ipfw add allow ip from any to any via lo0
ifpw add allow ip from $local_net to $local_net
ipfw add deny log ip from 180.0.0.0/8 to any in recv $ext_if
ipfw add check-state
ipfw add allow tcp from any to any out xmit $ext_if setup keep-state
ipfw add allow udp from any to any out xmit $ext_if keep-state
ipfw add allow icmp from any to any out xmit $ext_if keep-state
ipfw add allow icmp from any to any in recv $ext_if icmptypes 3,8,11
ipfw add deny ip from any to any
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this is for one host only, so i'm not so worried about interfaces..not
worried about icmp either..
I'm still seeing this traffic coming in, can anyone help with this
simpler config to keep 180.0.0.0 out?
IPF="ipfw -q add"
ipfw -q -f flush
#loopback
$IPF 10 allow all from any to any via lo0
$IPF 20 deny all from any to 127.0.0.0/8
$IPF 30 deny all from 127.0.0.0/8 to any
$IPF 40 deny tcp from any to any frag
$IPF 50 check-state
#$IPF 51 allow tcp from any to any established DISABLED PER SUGGESTION
#$IPF 52 allow all from any to any out keep-state DISABLED PER SUGGESTION
$IPF 53 allow icmp from any to any (am 0k with this)
#temp wide reaching filter
$IPF 137 deny all from 180.0.0.0/8 to any
#Allows for ports
$IPF 181 allow tcp from any to any 21
$IPF 183 allow tcp from any to any 25
#...........etc
#Another attempt to get rid of 180.x.x.x in case it is last match??
$IPF 450 deny all from 180.0.0.0/8 to any
#------------ deny and log everything
$IPF 499 deny udp from any to any
$IPF 5000 deny log all from any to any
$IPF 5010 deny icmp from any to any
--
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Paul Macdonald
IFDNRG Ltd
Web and video hosting
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