Date: Tue, 25 Mar 2003 11:20:08 +0200 From: Ruslan Ermilov <ru@FreeBSD.ORG> To: Scot <scotrn@cox.net> Cc: FreeBSD Stable <stable@FreeBSD.ORG>, ipfw@FreeBSD.ORG Subject: Re: Natd stops working on Firewall Message-ID: <20030325092007.GB73657@sunbay.com> In-Reply-To: <PAEEIJCHPFHEDADDGJFLEEHJDNAA.scotrn@cox.net>
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On Mon, Mar 24, 2003 at 09:52:32PM -0500, Scot wrote:
> Hi;
>
> Just setup my FreeBSD 4.7 Firewall using the docs
> outlined in the handbook.
>
What docs you have used to set up the firewall?
> The install went on and
> everything seems to be working fine then boom.
> The system seems to stop routing traffic. No
> messages in the security log or natd log as to why.
>
> I made sure it was logging by nmaping my box from the
> outside. I even ran natd in the foreground and it still didn't
> tell me what was going on.
>
> There is nothing in any logfile that tells me why this thing
> just stops working so I'm thinking it may not be a daemon but
> something in the kernel.
>
> I cannot ping the interface from the internal network but tcpdump shows
> the packets being received. (Hub network firewall_type=SIMPLE ).
>
> If I logon to the console the cable modem connection is still functioning
> and I can surf from the firewall.
>
> Any ideas on where to look next ??
>
>
> Cable modem using dhcp -> 192.168 home network on
> PPro w/280 MB ram.
> Intel Pro 10/100b/100+ Ethernet This card is a PCI card with 2 interfaces.
> Standard Xuser install + Kernel sources.
>
I've been through this just recently. Our "simple" prototype
is not production ready; if you just tune oip/iip/onet/inet,
etc., it won't allow your internal machines to talk outside.
The packet flow for a machine in ${inet}:${imask} talking outside
is as follows:
${inet}:${imask} -> some_host (in via ${iif})
${oip} -> some_host (out via ${oif}) (after NAT)
some_host -> ${inet}:${imask} (in via ${oif}) (after de-NAT)
some_host -> ${inet}:${imask} (out via ${iif})
(This assumes that you NAT using ${oip}, which is not always
the case.)
So, to make it work (if default is to "deny"), you need to add
the following rules at the end of the ruleset:
${fwcmd} add pass all from ${inet}:${imask} to any in via ${iif}
${fwcmd} add pass ip from ${oip} to any out via ${oif}
${fwcmd} add pass ip from any to ${inet}:${imask}
Cheers,
--
Ruslan Ermilov Sysadmin and DBA,
ru@sunbay.com Sunbay Software AG,
ru@FreeBSD.org FreeBSD committer,
+380.652.512.251 Simferopol, Ukraine
http://www.FreeBSD.org The Power To Serve
http://www.oracle.com Enabling The Information Age
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