From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: Re: ctnetlink kernel dump while running multiple libnfct clients Date: Tue, 29 Mar 2011 12:12:19 +0200 Message-ID: <4D91B083.2000001@netfilter.org> References: <4D908351.5010407@netfilter.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Netfilter Developer Mailing List To: Sam Roberts Return-path: Received: from mail.us.es ([193.147.175.20]:33024 "EHLO mail.us.es" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750994Ab1C2KM0 (ORCPT ); Tue, 29 Mar 2011 06:12:26 -0400 In-Reply-To: Sender: netfilter-devel-owner@vger.kernel.org List-ID: On 28/03/11 18:01, Sam Roberts wrote: > On Mon, Mar 28, 2011 at 5:47 AM, Pablo Neira Ayuso wrote: >> On 25/03/11 01:21, Sam Roberts wrote: >>> >>> Screenshot attached. >>> >>> At the time I had 3 connections to nfnetlink open >>> - a userspace connection tracker >> >> what protocol are you tracking from user-space? > > A dummy protocol for purposes of developing this prototype, I call it > "echo port broker". > > It listens on port 9999 for control connections. An echo port is > requested by the client, and server opens an ephemeral listen port and > returns the number. The client then reconnects to that ephemeral port, > which acts as an echo server. > >> AFAICS, the only way to hit this problem is to have some connection tracking >> helper in the kernel which overlaps your user-space helper, ie. someone is >> attaching a kernel helper to your conntrack. > > That's quite surprising, I've no firewall rules attaching anything > else to port 9999. See a dump of my rule setup at end of mail. Note it > assumes localhost client connects to localhost server. Please, send me the code so I can reproduce the problem here.