From owner-freebsd-net@freebsd.org Wed Mar 21 00:40:03 2018 Return-Path: Delivered-To: freebsd-net@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 4377FF5A514 for ; Wed, 21 Mar 2018 00:40:03 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from hz.grosbein.net (hz.grosbein.net [78.47.246.247]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "hz.grosbein.net", Issuer "hz.grosbein.net" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id BB6BE724CE for ; Wed, 21 Mar 2018 00:40:02 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from eg.sd.rdtc.ru (root@eg.sd.rdtc.ru [62.231.161.221] (may be forged)) by hz.grosbein.net (8.15.2/8.15.2) with ESMTPS id w2L0dnd7082983 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 21 Mar 2018 01:39:50 +0100 (CET) (envelope-from eugen@grosbein.net) X-Envelope-From: eugen@grosbein.net X-Envelope-To: rfg@tristatelogic.com Received: from [10.58.0.4] ([10.58.0.4]) by eg.sd.rdtc.ru (8.15.2/8.15.2) with ESMTPS id w2L0dcuT027057 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Wed, 21 Mar 2018 07:39:38 +0700 (+07) (envelope-from eugen@grosbein.net) Subject: Re: Raw Sockets: Two Questions To: "Ronald F. Guilmette" , freebsd-net@freebsd.org References: <98551.1521576540@segfault.tristatelogic.com> From: Eugene Grosbein Message-ID: <5AB1A9C5.9050707@grosbein.net> Date: Wed, 21 Mar 2018 07:39:33 +0700 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.7.2 MIME-Version: 1.0 In-Reply-To: <98551.1521576540@segfault.tristatelogic.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-Spam-Status: No, score=2.2 required=5.0 tests=BAYES_00, LOCAL_FROM, RDNS_NONE autolearn=no autolearn_force=no version=3.4.1 X-Spam-Report: * -2.3 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 2.6 LOCAL_FROM From my domains * 1.9 RDNS_NONE Delivered to internal network by a host with no rDNS X-Spam-Level: ** X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on hz.grosbein.net X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 21 Mar 2018 00:40:03 -0000 21.03.2018 3:09, Ronald F. Guilmette wrote: > I'm going to be doing some stuff with raw sockets pretty soon, and > while scrounging around, looking for some nice coding examples, I > found the following very curious comment on one particular message > board: > > https://stackoverflow.com/questions/7048448/raw-sockets-on-bsd-operating-systems > > "Using raw sockets isn't hard but it's not entirely portable. For > instance, both in BSD and in Linux you can send whatever you want, > but in BSD you can't receive anything that has a handler (like TCP > and UDP)." > > So, first question: Is the above comment actually true & accurate? Not for FreeBSD. > Second question: If the above assertion is actually true, then how can > nmap manage to work so well on FreeBSD, despite what would appear to be > this insurmountable stumbling block (of not being able to receive replies)? nmap uses libdnet that provides some portability layer, including RAW socket operations. It uses bundled stripped-down version but we have "normal" one as net/libdnet port/package. You should consider using it too as convenience layer.