From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [Bugme-new] [Bug 12109] New: Multicast packets with TTL 0 sent out if not local listener Date: Thu, 27 Nov 2008 09:34:12 -0800 Message-ID: <20081127093412.9536e5cc.akpm@linux-foundation.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: bugme-daemon@bugzilla.kernel.org, jani@ubuntu.com To: netdev@vger.kernel.org Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:52361 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751720AbYK0ReS (ORCPT ); Thu, 27 Nov 2008 12:34:18 -0500 In-Reply-To: Sender: netdev-owner@vger.kernel.org List-ID: (switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface). On Thu, 27 Nov 2008 02:32:27 -0800 (PST) bugme-daemon@bugzilla.kernel.org wrote: > http://bugzilla.kernel.org/show_bug.cgi?id=12109 > > Summary: Multicast packets with TTL 0 sent out if not local > listener > Product: Networking > Version: 2.5 > KernelVersion: 2.6.27 > Platform: All > OS/Version: Linux > Tree: Mainline > Status: NEW > Severity: normal > Priority: P1 > Component: IPV4 > AssignedTo: shemminger@linux-foundation.org > ReportedBy: jani@ubuntu.com > > > According to what I have read, setting the IP_MULTICAST_TTL option to 0 on a > multicast sending socket should prevent it sending to the network, and be > destined only for listeners on the local computer. > > This only seems to work if there is a local listener on that particular group. > If such a listener app is stopped other computers on the LAN get the messages, > and tcpdump -v shows they have TTL 0 > > I am not sure if this is intended behaviour but it is unexpected. > >