From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752268Ab0AYHhK (ORCPT ); Mon, 25 Jan 2010 02:37:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752088Ab0AYHhJ (ORCPT ); Mon, 25 Jan 2010 02:37:09 -0500 Received: from static-122-103-239-153.ng-fam.svips.gol.ne.jp ([122.103.239.153]:62209 "EHLO priv.dyadic.cynic.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752033Ab0AYHhI (ORCPT ); Mon, 25 Jan 2010 02:37:08 -0500 X-Greylist: delayed 556 seconds by postgrey-1.27 at vger.kernel.org; Mon, 25 Jan 2010 02:37:08 EST Date: Mon, 25 Jan 2010 16:27:49 +0900 From: Curt Sampson To: linux-kernel@vger.kernel.org Subject: Problems Receiving UDP Broadcasts on Some Versions of Linux Message-ID: <20100125072749.GG21419@analytic.cynic.net> Mail-Followup-To: Curt Sampson , linux-kernel@vger.kernel.org MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org I'm posting this here because it smells as if it may be something a where a kernel network code developer might just say, "oh yeah, obviously your problem is this." I'm not subscribed to this list, so please cc me on any replies. (The Mail-followup-to header may do this automatically for you.) The short summary is that on two very similar servers on the same network, an application that listens for broadcast UDP packets on a given port works fine on the Ubuntu 8.04/Linux 2.6.24-26-server box but does not receive the packets on the Ubuntu 9.04/Linux 2.6.28-17-server box. I have confirmed that tcpdump sees identical packets being received on both hosts. Did something change between these two kernel revisions that I need to listen differently? Full details, including sample code, are available at: http://stackoverflow.com/questions/2130563/udp-broadcast-reception-problems-with-ubuntu-9-04-but-not-8-04 Thanks for any help you can give me. Even if you're not sure, but have clues I should consider following up, feel free to e-mail me. I'm also happy to take pointers to kernel code I should read, if there's enlightenment there. cjs -- Curt Sampson +81 90 7737 2974 http://www.starling-software.com The power of accurate observation is commonly called cynicism by those who have not got it. --George Bernard Shaw