Date: Thu, 2 Apr 2009 15:00:56 +0700 From: Victor Sudakov <vas@mpeks.tomsk.su> To: freebsd-questions@freebsd.org Subject: Re: keep-state and divert Message-ID: <20090402080056.GA39348@admin.sibptus.tomsk.ru> In-Reply-To: <49D469A1.3060103@datapipe.net> References: <20090402055113.GA35989@admin.sibptus.tomsk.ru> <49D469A1.3060103@datapipe.net>
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Paul A Procacci wrote: > > > >I have read some recommendations on combining a stateful firewall with > >divert, > >e.g. > >http://www.derkeiler.com/Mailing-Lists/FreeBSD-Security/2003-06/0078.html > >and http://nuclight.livejournal.com/124348.html (the latter is in Russian). > > > >Do I understand correctly that it is (mathematically?) impossible to > >use the two together without also using "skipto"? > > > >If we consider a simple example below, how would you replace the 600th > >rule for a stateful one? > > > >00100 divert 8668 ip from any to table(1) out via rl0 > >00200 deny log logamount 100 ip from 10.0.0.0/8 to any out via rl0 > >00300 deny log logamount 100 ip from 172.16.0.0/12 to any out via rl0 > >00400 deny log logamount 100 ip from 192.168.0.0/16 to any out via rl0 > > > >00500 divert 8668 ip from table(1) to any in via rl0 > >00600 allow ip from table(1) to any in via rl0 > >00700 deny log logamount 100 ip from any to 10.0.0.0/8 in via rl0 > >00800 deny log logamount 100 ip from any to 172.16.0.0/12 in via rl0 > >00900 deny log logamount 100 ip from any to 192.168.0.0/16 in via rl0 > > > >65535 allow ip from any to any > > > >Thank you in advance for any input. > > > > > > Hopefully you don't mind a response which provides a fully functioning > firewall ruleset. It's by no means complete, but should give you the > answer to your question. > > http://procacci.me/ipfw.conf I have seen a number of such complete rulesets, some of them being very inventive and tricky. I see that your example also uses "skipto" with "keep-state". My question was however if it was possible to do without "skipto". And a simple example would be most appreciated, not a fully functional fuleset. I am also thinking about using "natd -deny_incoming" for keeping state, instead of "keep-state" rules. Is this feasible? -- Victor Sudakov, VAS4-RIPE, VAS47-RIPN sip:sudakov@sibptus.tomsk.ru
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