From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?ISO-8859-1?Q?Dan_No=E9?= Subject: Re: TUN/TAP hacking Date: Wed, 23 Jul 2008 22:25:28 -0400 Message-ID: <4887E818.4020305@isomerica.net> References: <20080723235514.GA8992@zenon.in.qult.net> Reply-To: dpn@isomerica.net Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: NetDev To: Ignacy Gawedzki , linux-kernel@vger.kernel.org Return-path: Received: from colobus.isomerica.net ([216.93.242.10]:43091 "EHLO colobus.isomerica.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751025AbYGXCga (ORCPT ); Wed, 23 Jul 2008 22:36:30 -0400 In-Reply-To: <20080723235514.GA8992@zenon.in.qult.net> Sender: netdev-owner@vger.kernel.org List-ID: Ignacy Gawedzki wrote: > I need some advice from network stack experts, so I hope this is the = right > place to ask. The Linux kernel networking folks hang out at netdev (netdev@vger.kernel.org). I've CC'd them... > I thought I'd be able to use the TAP interfaces to create some sort o= f a > network emulator. For a start I just "bridged" two tap interfaces, m= uch in > the same way as the example of br_select.c from http://vtun.sf.net , = assigned > both interfaces different IPv4 addresses (both with a /32 prefix), se= t them up > and tried to transmit a UDP packet from one address to the other thro= ugh the > bridge. Both logs from my bridge program and tcpdump tell me that th= e packets > are flowing as expected, but somehow the destination process doesn't = get the > packets (despite all correct bind, etc). >=20 > Is it simply that the stack inconditionally drops any packet with the= same > source (IP and/or MAC) address as some local interface? >=20 > As ARP resolution seems not to work either (I had to put permanent en= tries in > the neighbor table), I suppose this is the case indeed. >=20 > Could anyone confirm that? (please CC me, I've not subscribed) >=20 > Thanks, >=20 > Ignacy >=20 --=20 /--------------- - - - - - - | Dan No=E9 | http://isomerica.net/~dpn/