From owner-freebsd-net@FreeBSD.ORG Sun Feb 1 21:49:03 2009 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8B37F1065672 for ; Sun, 1 Feb 2009 21:49:03 +0000 (UTC) (envelope-from dlt@mebtel.net) Received: from mail960c35.nsolutionszone.com (mail960c35.nsolutionszone.com [209.235.152.150]) by mx1.freebsd.org (Postfix) with ESMTP id 3DC208FC08 for ; Sun, 1 Feb 2009 21:49:02 +0000 (UTC) (envelope-from dlt@mebtel.net) X-POP-User: dlt.mebtel.net Received: from localhost (66-79-79-183.dsl.mebtel.net [66.79.79.183]) by mail960c35.nsolutionszone.com (8.13.6.20060614/8.13.1) with ESMTP id n11IUvoS003719 for ; Sun, 1 Feb 2009 18:30:58 GMT Date: Sun, 1 Feb 2009 13:30:57 -0500 From: Derek Tattersall To: freebsd-net@freebsd.org Message-ID: <20090201183057.GA47405@oriental.arm.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.2.3i Subject: Multicast source address in recvfrom() X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: dlt@mebtel.net List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Feb 2009 21:49:03 -0000 In order to become familiar with multicast implementation using FreeBSD, I found via Google a pair of test programs which multicast sent a simple text message and received the text message. I added some code to report the source address, because none of the references that I looked at specified the source IP address in the frame. I ran the sender on A -current system, AMD64 vintage last week. The receiver was on a -current system I386 vintage last week. TCPDUMP shows the source IP address in the frame as (correctly) 192.168.0.15. The receiver reports the source IP address as 200.231.191.191. I have also run the same test with an OpenBSD 4.4 Release I386 system as the receiver. The openBSD system reports the sender as 192.168.0.15. A Fedora 10 system reported the source IP address as 0.0.0.0. Googling the RFCs and other information and referring to Comer's and Stevens' books on TCPIP I can't determine what should be reported. Does anybody have clue for me? -- Best regards, Derek Tattersall dlt@mebtel.net dlt666@yahoo.com dtatters@gmail.com