From mboxrd@z Thu Jan 1 00:00:00 1970 From: Krzysztof Halasa Subject: Re: Linux, tcpdump and vlan Date: Thu, 19 Jul 2007 16:23:48 +0200 Message-ID: References: <878246.51044.qm@web56608.mail.re3.yahoo.com> <469E9AC8.3090603@trash.net> <20070719144131.0c230c8f@oldman.hamilton.local> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Patrick McHardy , andrei radulescu-banu , linux-kernel@vger.kernel.org, Linux Netdev List To: Stephen Hemminger Return-path: Received: from khc.piap.pl ([195.187.100.11]:57650 "EHLO khc.piap.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755886AbXGSOXu (ORCPT ); Thu, 19 Jul 2007 10:23:50 -0400 In-Reply-To: <20070719144131.0c230c8f@oldman.hamilton.local> (Stephen Hemminger's message of "Thu, 19 Jul 2007 14:41:31 +0100") Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Stephen Hemminger writes: > 1) non-accelerated device > * all frames show in promiscious mode > * tag is part of the frame that shows up > in tcpdump, and then gets stripped by the 8021q module. Sure. It's IMHO good and working, modulo the tag being removed on the master device (optional cloning or something, IIRC). > 2) rx tag stripping device > * all frames show in promiscious mode > * tag is in skb but NOT passed to tcpdump > 3) rx vlan acceleration > * only frames that for vlan's that are registered show up > in promisicous mode > * tag is in skb but NOT passed to tcpdump I wasn't aware of devices doing 3. Aren't we able to tell them to receive all packets anyway (even unknown VLANs#)? > Unfortunately, the tag is lost as part of the VLAN acceleration process > so it is not a simple matter of changing code in AF_PACKET receive > to restore the tag. I'm not sure if we really want it. If needed we can disable acceleration, can't we? While accelerated we can see the packets (without tags) on logical devices. However seeing unknown tags on master device (with tcpdump etc) would certainly be useful. -- Krzysztof Halasa