Date: Sun, 21 Apr 2002 01:20:05 -0700 (PDT) From: "Crist J. Clark" <cjc@FreeBSD.ORG> To: freebsd-bugs@FreeBSD.org Subject: Re: misc/37301: 4.5 rc.firewall type simple does not pass icmp, or inside to gateway udp Message-ID: <200204210820.g3L8K5A83976@freefall.freebsd.org>
next in thread | raw e-mail | index | archive | help
The following reply was made to PR misc/37301; it has been noted by GNATS.
From: "Crist J. Clark" <cjc@FreeBSD.ORG>
To: Earl Killian <earl@killian.com>
Cc: freebsd-gnats-submit@FreeBSD.ORG
Subject: Re: misc/37301: 4.5 rc.firewall type simple does not pass icmp, or inside to gateway udp
Date: Sun, 21 Apr 2002 01:19:05 -0700
On Sat, Apr 20, 2002 at 05:35:31PM -0700, Earl Killian wrote:
> >Description:
> I tried the 4.5-RELEASE rc.firewall with firewall_type="simple" and
> natd_enable="YES", and I was not able to talk to my gateway machine
> from the hosts on the inside. Looking at the rules below, I see only
> one rule that is specific to iif, and that is just to prevent the
> inside from pretending to be outside. Most of the rules are via oif,
> or to oip and so don't apply to an inside machine talking to iip via
> iif. If I eliminate those rules, I'm left with:
>
> Rules that apply to inet:imask talking to iip via iif:
>
> deny all from any to 127.0.0.0/8
> deny ip from 127.0.0.0/8 to any
> deny all from ${onet}:${omask} to any in via ${iif}
> pass tcp from any to any established
> pass all from any to any frag
> pass tcp from any to any setup
>
> So what about icmp and udp?
You are missing,
# Allow access to our DNS
${fwcmd} add pass tcp from any to ${oip} 53 setup
${fwcmd} add pass udp from any to ${oip} 53
${fwcmd} add pass udp from ${oip} 53 to any
Which allow internal machines to reach the DNS server on the
gateway. Remember,
############
# This is a prototype setup for a simple firewall. Configure this
# machine as a named server and ntp server, and point all the machines
# on the inside at this machine for those services.
############
(Not that that the rules actually work for NTP. ;)
> Do other sites really use this fw and
> just not ping or dns/ntp to their gateway from inside?
I hope no one uses it unmodified. You shouldn't. As it is documented
elsewhere in rc.firewall,
# For ``client'' and ``simple'' the entries below should be customized
# appropriately.
############
# This is a prototype setup for a simple firewall.
You should NOT use these rules as is. They don't make a lot of
sense. Trying to make a default set of firewall rules is a fools
game. No one would be happy with them. I'd prefer to have a completely
broken set of rules. If you don't understand your own firewall rules,
you shouldn't be building your own firewall. A false-sense of security
is worse than having less security and knowing it.
--
Crist J. Clark | cjclark@alum.mit.edu
| cjclark@jhu.edu
http://people.freebsd.org/~cjc/ | cjc@freebsd.org
To Unsubscribe: send mail to majordomo@FreeBSD.org
with "unsubscribe freebsd-bugs" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200204210820.g3L8K5A83976>