From owner-freebsd-questions@FreeBSD.ORG Fri Aug 4 04:02:45 2006 Return-Path: X-Original-To: questions@freebsd.org Delivered-To: freebsd-questions@FreeBSD.ORG Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id B2AD416A4DA for ; Fri, 4 Aug 2006 04:02:45 +0000 (UTC) (envelope-from benlutz@datacomm.ch) Received: from popeye1.ggamaur.net (popeye1.ggamaur.net [213.160.40.50]) by mx1.FreeBSD.org (Postfix) with ESMTP id A685E43D49 for ; Fri, 4 Aug 2006 04:02:39 +0000 (GMT) (envelope-from benlutz@datacomm.ch) Received: from maxlor.mine.nu (c-213-160-32-54.customer.ggaweb.ch [213.160.32.54]) by popeye1.ggamaur.net (8.13.7/8.13.7/Submit) with ESMTP id k7442aEm014880 for ; Fri, 4 Aug 2006 06:02:37 +0200 (CEST) (envelope-from benlutz@datacomm.ch) Received: from localhost (unknown [127.0.0.1]) by maxlor.mine.nu (Postfix) with ESMTP id F3BCA2E109 for ; Fri, 4 Aug 2006 06:02:30 +0200 (CEST) X-Virus-Scanned: amavisd-new at atlantis.intranet Received: from maxlor.mine.nu ([127.0.0.1]) by localhost (atlantis.intranet [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id BlVzSYIMeSuS for ; Fri, 4 Aug 2006 06:02:30 +0200 (CEST) Received: from mini.intranet (mini.intranet [10.0.0.17]) by maxlor.mine.nu (Postfix) with ESMTP id B9F892E05C for ; Fri, 4 Aug 2006 06:02:30 +0200 (CEST) From: Benjamin Lutz To: questions@freebsd.org Date: Fri, 4 Aug 2006 06:02:25 +0200 User-Agent: KMail/1.9.1 X-Face: $Ov27?7*N,h60fIEfNJdb!m,@#4T/d; 1hw|W0zvsHM(a$Yn6BYQ0^SEEXvi8>D`|V*F"_+R 2@Aq>+mNb4`,'[[%z9v0Fa~]AD1}xQO3|>b.z&}l#R-_(P`?@Mz"kS; XC>Eti,i3>%@g?4f,\c7|Gh wb&ky$b2PJ^\0b83NkLsFKv|smL/cI4UD%Tu8alAD MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1327891.zGBWxTohYJ"; protocol="application/pgp-signature"; micalg=pgp-sha1 Content-Transfer-Encoding: 7bit Message-Id: <200608040602.29799.benlutz@datacomm.ch> X-Scanned-By: MIMEDefang 2.57 on 213.160.40.60 Cc: Subject: IP broadcasts X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 04 Aug 2006 04:02:45 -0000 --nextPart1327891.zGBWxTohYJ Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Content-Disposition: inline Hello, I've been playing around with IP packets tonight, and I've noticed a peculi= ar=20 behaviour in FreeBSD that I can't explain. Can someone provide some insight? Specifically, I've been sending IP packets to broadcast addresses, once to= =20 10.0.0.255, which is the local subnet's broadcast address, and once to=20 255.255.255.255, which as I understand it, is a general broadcast address.= =20 The first broadcast (to 10.0.0.255) works, the second (to 255.255.255.255)= =20 doesn't. Looking at it with tcpdump on the sending machine, I see this: 05:46:52.057994 00:12:17:5a:b3:b6 > ff:ff:ff:ff:ff:ff, ethertype IPv4=20 (0x0800), length 136: 10.0.0.1 > 10.0.0.255: ip-proto-255 102 05:47:16.472315 00:12:17:5a:b3:b6 > 00:40:63:d9:a9:28, ethertype IPv4=20 (0x0800), length 136: 10.0.0.1 > 255.255.255.255: ip-proto-255 102 In other words, the packet to 10.0.0.255 is has a destination MAC address o= f=20 ff:ff:ff:ff:ff:ff, so all machines on the subnet receive it. The second=20 packet has the destination MAC of my gateway, so only that machine receives= =20 it, the other machines on the net don't see it (the ethernet uses a switch). Things work as expected when sending the packets from a Linux machine. Mayb= e=20 there's some socket option or sysctl I need to set? Cheers Benjamin --nextPart1327891.zGBWxTohYJ Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) iD8DBQBE0sbVgShs4qbRdeQRAlLZAJ93RW5febIlktpNMia5Y6MiqhOSiACdGT26 kIsGlsmb8I+4/qXRwFaewqc= =RQL2 -----END PGP SIGNATURE----- --nextPart1327891.zGBWxTohYJ--