Date: Fri, 16 Sep 2005 14:27:51 +0200 From: Jeremie Le Hen <jeremie@le-hen.org> To: freebsd-ipfw@FreeBSD.ORG, vladone <vladone@spaingsm.com> Subject: Re: in via or in recv Message-ID: <20050916122751.GC51142@obiwan.tataz.chchile.org> In-Reply-To: <200509151332.j8FDWoqd035125@lurza.secnetix.de> References: <1126236392.20050901000512@spaingsm.com> <200509151332.j8FDWoqd035125@lurza.secnetix.de>
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Hi, > vladone <vladone@spaingsm.com> wrote: > > What is difference between: > > 1. in via - in recv > > No difference. When checking incoming packets (which "in" > means), only the receiving interface is known, but not yet > the transmitting interface, so "via" and "recv" do the same > thing in that case. > > > 2. out via - out xmit > > When checking outgoing packets ("out"), both the receiving > and the transmitting interface are known, so "via" compares > with both, while "xmit" only compares with the transmitting > interface. That's why "xmit" can only be used with "out", > not with "in", while "recv" can be used with both "out" and > "in". > > All of that is explained in detail in the ipfw(8) manpage. > > > When need to use an variant or another? > > That depends on what you want to do. In my experience > there is rarely a need for "via". Usually you only need > "recv" and "xmit" (optionally combined with "in" and "out" > as appropriate for your rules). Given that this question is regurlarly asked, I've just written a webpage explaining the difference among "via", "xmit" and "recv", based on what has been said here in the past and my own understanding of ipfw code. http://tataz.chchile.org/~tataz/ipfw_via_recv_xmit.html This is quite short to read, and I would like some feedback on it. Best regards, -- Jeremie Le Hen < jeremie at le-hen dot org >< ttz at chchile dot org >
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