Date: Sun, 19 Oct 2003 17:04:42 +0100 From: Dan <dan@ntlbusiness.com> To: Barney Wolff <barney@databus.com> Cc: freebsd-net@freebsd.org Subject: Re: IPFW. Message-ID: <200310191704.42446.dan@ntlbusiness.com> In-Reply-To: <20031019155913.GA46989@pit.databus.com> References: <200310191532.40136.dan@ntlbusiness.com> <20031019155913.GA46989@pit.databus.com>
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On Sunday 19 October 2003 4:59 pm, you wrote:
> On Sun, Oct 19, 2003 at 03:32:40PM +0100, Dan wrote:
> > Hi there.
> > I hope you can help.
> > I've been trying and trying for days to try and get these rules sorted,
> > as whenever they're used, my laptop (which is using my FreeBSD box as a
> > gateway) cannot access the Internet.
>
> I suggest you put "log" on all your denies, and by ipfw -atde list
> see which rules are stopping the packets.
>
> Aside from whether the ruleset works, it seems inconsistent. If you're
> going to keep state, you should not be allowing tcp established, but
> instead setting up state on setup, both ways. btw, "pass" means allow,
> did you mean "deny"?
Hi there. Thank you very much for your reply.
I couldn't see anything obvious in ipfw -atde list - and I tried requestnig a
new page from the laptop, but saw nothing new there.
I've taken what you said -- and as far as I can understand (sorry..this is
really hard to me) I've come up with:
Is this better? thanks again!
# Define the firewall command (as in /etc/rc.firewall) for easy
# reference. Helps to make it easier to read.
fwcmd="/sbin/ipfw"
# Force a flushing of the current rules before we reload.
$fwcmd -f flush
# Divert all packets through the tunnel interface.
$fwcmd add 50 divert natd all from any to any via sis0
# Allow all connections that have dynamic rules built for them,
# but deny established connections that don't have a dynamic rule.
# See ipfw(8) for details.
$fwcmd add check-state
$fwcmd add pass tcp from any to any keep-state
# Allow all localhost connections
${fwcmd} add 100 pass all from any to any via lo0
${fwcmd} add 200 deny log all from any to 127.0.0.0/8
${fwcmd} add 300 deny log ip from 127.0.0.0/8 to any
# Allow all connections from my network card that I initiate
$fwcmd add allow tcp from me to any out xmit any setup keep-state
$fwcmd add deny log tcp from me to any
$fwcmd add allow ip from me to any out xmit any keep-state
$fwcmd add allow all from 192.168.0.0/24 to any
# Everyone on the Internet is allowed to connect to the following
# services on the machine. This example specifically allows connections
# to sshd and a webserver.
$fwcmd add allow tcp from any to any keep-state
$fwcmd add allow tcp from any to me 80 setup
$fwcmd add allow tcp from any to me 22 setup
# This sends a RESET to all ident packets.
$fwcmd add reset log tcp from any to me 113 in recv any
# Enable ICMP: remove type 8 if you don't want your host to be pingable
$fwcmd add allow icmp from any to any icmptypes 0,3,8,11,12,13,14
# Deny all the rest.
$fwcmd add deny log ip from any to any
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