From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick McHardy Subject: Re: [PATCH 8/9] netfilter: xtables: inclusion of xt_TEE Date: Tue, 23 Mar 2010 13:38:25 +0100 Message-ID: <4BA8B641.5070700@trash.net> References: <1268831945-6041-1-git-send-email-jengelh@medozas.de> <1268831945-6041-9-git-send-email-jengelh@medozas.de> <4BA0DAB3.3000700@trash.net> <4BA7A1C8.8050402@trash.net> <4BA8AE4A.5090805@trash.net> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Content-Transfer-Encoding: 7bit Cc: netfilter-devel@vger.kernel.org To: Jan Engelhardt Return-path: Received: from stinky.trash.net ([213.144.137.162]:56959 "EHLO stinky.trash.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751988Ab0CWMi0 (ORCPT ); Tue, 23 Mar 2010 08:38:26 -0400 In-Reply-To: Sender: netfilter-devel-owner@vger.kernel.org List-ID: Jan Engelhardt wrote: > On Tuesday 2010-03-23 13:04, Patrick McHardy wrote: >>>>> Setting IP_DF on the cloned skb could possibly lead to a Packet Too >>>>> Big being sent back to the original sender - which should probably be >>>>> avoided too. >>>> Indeed. This might also happen if the packet is passed through another >>>> router of course. >>> Right. So let's set IP_DF on the teed packet and let the sender >>> reduce its packet size to accomodate for the (hidden) tee route :) >>> >>> Is it ok if the Packet Too Big notification is received by the >>> original sender much later than an acknowledgement in reception to >>> the packet? >> I think its the responsibility of the admin to make sure that >> doesn't happen. > > Is that so? He's the one duplicating packets on purpose, so yes. > 1. sending the clone through a tunnel - admin can't do much about MTU getting > smaller here. It either happens locally (before encapsulation) or for the encapsulated packets, which isn't a problem. > 2. the PTB may take longer to reach the source due to internet > routing - nothing the admin can really influence either. He should make sure any messages generated in response to duplicated packets are not routed or dropped.