Date: Tue, 25 Feb 2003 16:29:03 -0800 From: "Joshua Lokken" <bsdaemon@eudoramail.com> To: "Joshua Lokken" <bsdaemon@eudoramail.com>, "Giorgos Keramidas" <keramida@ceid.upatras.gr> Cc: freebsd-questions@FreeBSD.ORG Subject: Re: Fwd: ipfw rule placement Message-ID: <LAOLBNHGMPNEHBAA@whowhere.com>
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On Wed, 26 Feb 2003 02:25:12 Giorgos Keramidas wrote: >On 2003-02-25 16:09, Joshua Lokken <bsdaemon@eudoramail.com> wrote: >> When I remove the default deny rule from the list, nat works fine, >> port redirections and all, but with the deny rule in place, nat >> isn't working, so I'm thinking I have a rule in the wrong place. >> Can anyone point out any obvious missing/misplaced rules here? > >For NAT to be working, you hav to make sure natd(8) is running and has >a proper configuration file. > >Now, as far as the ipfw(8) rules are concerned, try using the >following ruleset: > ># $fwcmd -f flush ># $fwcmd add allow all from any to any via lo0 ># $fwcmd add divert natd all from any to any via $oif ># $fwcmd add allow icmp from any to any icmptypes 3,4,11,12 ># $fwcmd add check-state ># $fwcmd add allow udp from $oip to any via $oif keep-state ># $fwcmd add allow tcp from any to $oip 22,80,443,6346,22002,22003,22010 setup via $oif keep-state ># $fwcmd add allow ip from $oip to any keep-state out via $oif ># $fwcmd add allow ip from $inwr to any keep-state via $iif ># $fwcmd add 65435 deny log ip from any to any > >The changes from your own set of rules are summarized below: > > - moved icmp checking higher, since they're unrelated to tcp or udp > and state checking > > - added a rule for udp packets, since DNS resolving and a few other > useful things depend on them > > - moved check-state higher, to minimise the delay for packets that > are parts of an existing connection (ipfw rules are checked > sequentially, from start to end) > > - added keep-state in your 'setup' rule for incoming connections to > $oip and 'via $oif' to make sure that packets destined for $oip > are only accepted on $oif (good measure against spoofing) > >Before using this set of rules, make sure you give proper values to >$iip, $oip, $iif, $oif and $inwr. > >- Giorgos > Indeed! I do have the variables listed defined, and have natd configured and working. Thank you very much--not only did you answer my question, but gave me a better understanding of ipfw! Joshua Need a new email address that people can remember Check out the new EudoraMail at http://www.eudoramail.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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