Return-path: Received: from purr.warmcat.com ([87.106.142.209]:33776 "EHLO mailserver.mog.warmcat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753753AbXHFIZf (ORCPT ); Mon, 6 Aug 2007 04:25:35 -0400 Message-ID: <46B6DAFC.7020301@warmcat.com> Date: Mon, 06 Aug 2007 09:25:32 +0100 From: Andy Green MIME-Version: 1.0 To: Johannes Berg CC: Ulrich Kunitz , linux-wireless , Daniel Drake Subject: Re: mac80211 driver interface semantics References: <46B27729.5030406@gentoo.org> <20070803052935.GA12683@deine-taler.de> <46B2E06F.4090706@warmcat.com> <1186134894.4647.24.camel@johannes.berg> <46B3032C.5040306@warmcat.com> <1186137166.4647.34.camel@johannes.berg> <46B304FF.3000305@warmcat.com> <1186137715.4647.36.camel@johannes.berg> <46B30828.3000507@warmcat.com> <1186382658.21957.45.camel@johannes.berg> In-Reply-To: <1186382658.21957.45.camel@johannes.berg> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-wireless-owner@vger.kernel.org List-ID: Somebody in the thread at some point said: > On Fri, 2007-08-03 at 11:49 +0100, Andy Green wrote: > >> ''Because if you have both a hard monitor and a regular interface >> (monitor_during_oper allowed) then we will never check the CRC on frames >> that enter the networking path and can get corrupted TCP packets in etc.'' >> >> If the rest of the networking stack didn't trust the packet anyway and >> confirms the IP-level checksum, then it can make its own opinion about >> the packet. > > Maybe it helps if I add that the FCS covers more of the packet than the > IP checksum; hence, if the FCS fails due to a bit in the area the IP > checksum does not cover we will not ACK the packet and get a > retransmission, but the IP checksum will check out as good and we'll > have a duplicate packet. Fair enough, thanks for the explanation. -Andy